Merge remote-tracking branch 'origin/master' into stable

.github/workflows/ci.yaml

@@ -48,6 +48,16 @@ jobs:
       - uses: jdx/mise-action@v3
         name: Install mise
 
+      - name: Cache Go modules and build
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
       - name: Run tests
         run: mise tasks run covtest
 
@@ -69,6 +79,16 @@ jobs:
       - uses: jdx/mise-action@v3
         name: Install mise
 
+      - name: Cache Go modules and build
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
       - name: Run fuzzing
         run: mise tasks run 'test:fuzz:*'
 
@@ -86,6 +106,16 @@ jobs:
       - uses: jdx/mise-action@v3
         name: Install mise
 
+      - name: Cache Go modules and build
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
       - name: Run linter
         run: mise tasks run lint
 
@@ -123,14 +153,6 @@ jobs:
       - name: Setup BuildX
         uses: docker/setup-buildx-action@v3
 
-      - name: Setup cache
-        uses: actions/cache@v5
-        with:
-          path: /tmp/buildx-cache
-          key: ${{ runner.os }}-buildx-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-buildx-
-
       - name: Login to DockerHub
         if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
@@ -147,7 +169,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Build and push
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           pull: true
           context: .
@@ -155,5 +177,5 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=local,src=/tmp/buildx-cache
-          cache-to: type=local,dest=/tmp/buildx-cache
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

.github/workflows/govulncheck.yml

@@ -35,6 +35,7 @@ jobs:
       uses: actions/setup-go@v6
       with:
         go-version-file: go.mod
+        cache: true
 
     - name: Check for vulnerabilities
       run: |

.goreleaser.yml

@@ -54,6 +54,8 @@ archives:
       - LICENSE
       - README.md
       - SECURITY.md
+      - BEST_PRACTICES.md
+      - example.config.toml
 
 gomod:
   proxy: true

.mise.toml

@@ -33,11 +33,11 @@ run = "govulncheck ./..."
 
 [tasks.test]
 description = "Run tests"
-run = "go test -v ./..."
+run = "go test -v -race ./..."
 
 [tasks.covtest]
 description = "Run tests with code coverage"
-run = "go test -coverprofile=coverage.txt -covermode=atomic -parallel 2 -race -v ./..."
+run = "go test -coverprofile=coverage.txt -covermode=atomic -count=2 -race -v ./..."
 
 [tasks.test-all]
 description = "Run all tests"
@@ -48,7 +48,7 @@ depends = [
 
 [tasks."test:fuzz:client-hello"]
 description = "Run fuzzy test for ClientHello"
-run = "go test -v {{ vars.fuzzflags }} -fuzz=FuzzClientHello ./mtglib/internal/faketls"
+run = "go test -v {{ vars.fuzzflags }} -fuzz=FuzzReadClientHello ./mtglib/internal/tls/fake"
 
 [tasks."test:fuzz:client-handshake"]
 description = "Run fuzzy test for ClientHandshake"

BEST_PRACTICES.md

@@ -0,0 +1,55 @@
+# Best practices
+
+This is unfortunate, but since 2018 many things were changed. Most of them
+became way worse. Previous iterations of censorship systems were very dumb,
+DPI were primitive and filtered very obvious things. Nowadays they are
+way more intelligent and it is very naive to treat them frivolously.
+
+In 2026 is not enough to pretend that your mtg installation is a Microsoft
+website that sits in Amsterdam Digital Ocean location. Now your installation
+has to be a website that is mtg in disguise. Yes, it requires a bit more effort
+but this effort is probably less than rotating proxies each other day.
+
+mtproto traffic, even with FakeTLS, has its specifics that are probably
+very well known by DPI systems. These specifics are not something unique but
+could mark an IP address as suspicious. Now let's think:
+
+1. You have a proxy in Amsterdam Digital Ocean that tells it is microsoft.com
+   how hard could it be to find out that this is probably fake? 1 or probably 2
+   DNS queries for `microsoft.com`? In case of some CDN, there are ECS-powered
+   resolvers that are very capable to return results from POV of some subnets.
+   If censor sees no relevant results, will they be afraid to block IP?
+2. You have a proxy in Amsterdam Digital Ocean that tells it is a website from
+   the same public subnet. But not the same. Would it be hard to make these DNS
+   queries and ban IP?
+
+The correct way of having this proxy is following:
+
+1. Register a domain name
+2. Get some VPS, probably in your domestic location
+3. Set that domain name from a step 1 to IP address of that VPS
+4. Generate a couple of HTML pages by LLMs or even copy them from elsewhere
+5. Set some webserver and issue TLS certificates with Let's Encrypt or any other
+   name
+6. Set mtg before this webserver.
+7. Use sing-box or anything like that to provide local socks5 interface and
+   have VPNized uplinks
+8. Set up mtg to use socks5 from a 7 step.
+
+In that case you will get a match of DNS and SNI in requests. As a side effect,
+your proxy will work with XTLS and its friends: XTLS in sniff mode ignores
+IP address a client wants to connect to. Instead, it reads SNI and connect
+to resolved address: a clever idea if user does not have a trustworthy DNS
+set up.
+
+Yes, this is much longer that usual technique, and requires more effort. But
+this is could probably be very well automated to some reasonable extent.
+
+Unfortunately, this is a best practice right now.
+
+Do not also forget about other implementation, like
+[telemt](https://github.com/telemt/telemt). Try everything. Use VPNs. It does
+not really matter which project you are going to use as long it helps you to
+stay connected.
+
+_March 2026._

Dockerfile

@@ -5,14 +5,19 @@ FROM golang:1.26-alpine AS build
 
 ENV CGO_ENABLED=0
 
-RUN set -x \
-  && apk --no-cache --update add \
-    bash \
-    ca-certificates \
-    git
+RUN --mount=type=cache,target=/var/cache/apk \
+    set -x \
+    && apk --update add \
+      bash \
+      ca-certificates \
+      git
+
+COPY go.mod go.sum /app/
+WORKDIR /app
+
+RUN go mod download
 
 COPY . /app
-WORKDIR /app
 
 RUN set -x \
   && version="$(git describe --exact-match HEAD 2>/dev/null || git describe --tags --always)" \

README.md

@@ -38,6 +38,33 @@ goal: to give a possibility to connect to Telegram in a restricted,
 censored environment. But it does it slightly differently in details
 that probably matter.
 
+* **Domain fronting**
+
+  For years mtg supports domain fronting. This technique means that it fallbacks
+  to accessing a real website in case if request fails. It could fail by many
+  reasons: anti-replay protection, accidental access to the webserver or
+  stale request. Anyway, if mtg rejects this request, it does not break a
+  connection. It connects to the websites and replicates everything that client
+  has sent, and simply proxies it back as is. Users will see a response from
+  the real website, _byte-to-byte identical_ to the response of the real netloc.
+
+* **Doppelganger**
+
+  mtg also is a doppelganger of the website it fronts. Sure, with domain fronting
+  users will see replies of the real website in case if something will go wrong.
+  But what about such cases when _everything is fine_?
+
+  In that case mtg mimics TLS connection statistical characteristics as close as
+  possible. Different application have different statistics of their patterns.
+  Big CDN steadily pumping the data, small websites burst with short easily
+  compressiable chunks of traffic.
+
+  mtg artificially emulates those delays to be statistically indistinguishable
+  from the real website even if it covers connection of the very specific app.
+  It also follows 2 most common patterns of traffic chunking, so censors
+  will have to put more resources to find out that we have Telegram here
+  but not a hookah webshop served by nginx.
+
 * **Resource-efficient**
 
   It has to be resource-efficient. It does not mean that you will see
@@ -93,6 +120,8 @@ that probably matter.
   software (written in Golang) with a minimum effort + you can replace
   some parts with those you want.
 
+Please also to read about [best practices](https://github.com/9seconds/mtg/blob/master/BEST_PRACTICES.md).
+
 ### Version 2
 
 If you use version 1.x before, you are probably noticed some major
@@ -398,6 +427,55 @@ or if you are using docker:
 $ docker exec mtg-proxy /mtg access /config.toml
 ```
 
+## Doppelganger
+
+mtg can mimic real websites, please take a look at relevant section in example
+config file.
+
+mtg comes with some very good precollected statistics coming from
+[ok.ru](https://ok.ru/). It does not mean that you have to cover yourself
+by pretending that mtg is _ok.ru_. **Do not do that: ok.ru comes from very specific
+ASNs, but not from VPS providers you are going to use.** What I want to say
+is that defaults are very good enough to use as is because ok.ru for public
+pages has a very generic profile of TLS packets delay.
+
+But for better results it is recommended to teach mtg about the website you
+will use as a domain front. In order to do that, you need to specify URLs
+from this website. Just go to it, open WebDeveloper console and pick up
+random URLs. For better results they have to be **from the same domain name
+you are going to use as a disguise** but serve light and heavy content: pages,
+images etc. Do not use many, 2-3 will probably work.
+
+mtg will crawl these pages periodically, accumulating statistics and
+using it as you go.
+
+```toml
+[defense.doppelganger]
+urls = [
+  "https://lalala.com/index.html",
+  "https://lalala.com/contacts.html",
+]
+```
+
+This is not very necessary. Keep in mind these rules:
+
+1. If you are not sure what is this all about, do nothing. Defaults are good.
+2. All URLs must be HTTPS
+3. All URLs should be from the same domain name (but this is not a rule)
+4. Do not use a lot of pages. Use _different_ pages. mtg will start using this
+   statistics when it will accumulate enough anyway.
+5. These URLs should be directly accessible from mtg without proxies whatsoever
+6. Do not create huge raids. mtg will repeatedly crawl in raids, making N repeats.
+   Do not use high N, you do not want to be noticeable.
+7. It makes no sense to have small delay between raids. Usually webservers
+   do not update their TLS settings each hour.
+8. If you have some specific knowledge if webserver is using
+   [TLS Dynamic Record Sizing](https://blog.cloudflare.com/optimizing-tls-over-tcp-to-reduce-latency/), you
+   can use a very specific setting. This are Cloudflare, Go standard webservers,
+   [caddy](https://caddyserver.com/) and [H2O](https://h2o.examp1e.net/). If so,
+   you can enable `drs` setting.
+9. **If you are not sure, touch nothing!**
+
 ## Metrics
 
 Out of the box, mtg works with

example.config.toml

@@ -206,6 +206,66 @@ tcp = "5s"
 http = "10s"
 idle = "1m"
 
+# mtg has to mimic real websites. It does not mean domain fronting, it also
+# means that traffic characteristics should be similar to real world traffic.
+# websites and applications behave differently, their traffic patterns are also
+# different. Applications do bursts of RPC-style messages (or JSON communication,
+# does not really matter), while websites pump heavy content in HTTP2 streams
+#
+# It means that statistically there is a different between traffic shape:
+# delays between packets are also different.
+# In order to avoid censorship detection based on these patterns, there is a
+# mtg subsystem called "Doppelganger" that aims to mimic website statistics
+# as close as it could.
+#
+# Delays between TLS packets are not constant. There are many factors
+# that come in play. Application should generate some response, it could
+# send some headers first and stream content with chunked encoding. So
+# some first packets could come as soon as possible, with some delays
+# after first ones. Such phenomenon is described by different statistic
+# distribution. There are 2 distribution that describe it: lognormal
+# distribution and Weibul distribution. Lognormal is all about steady streams
+# of heavy content like a video. Weibul is great about short bursts like
+# user who requested a static page an a couple of images.
+[defense.doppelganger]
+# This is a list of URLs that would be crawled by mtg to approximate delay
+# statistics. They MUST be HTTPS urls.
+#
+# You can come to the website and collect different URLs, with light and
+# heavy content. We recommend to search for CDNs.
+urls = [
+    # "https://st-ok.cdn-vk.ru/res/react/vendor/clsx-2.1.1-amd.js"
+]
+# A collection is done in raids. Each raid makes this number of requests to
+# each URL in this list. Do not use a huge number, 10 is probably ok.
+repeats-per-raid = 10
+# This is a duration between each raid. It makes no sense to have a small number
+# here as you would start to make a noticeable activity. Usually traffic patterns
+# do not change a lot, so do not expect different results if you request
+# each 10 minutes.
+raid-each = "6h"
+# This enables dynamic tls record sizing.
+#
+# Some modern stacks and platforms start to use the technique that is called
+# DRS. They start with small TLS packets and ramp up eventually. First packets
+# are usually about MTU size, after that we get 4k and eventually max size.
+# This is done with a good intention: to minimize a time to the first byte,
+# so application could start doing something with the data right after first
+# RTT.
+#
+# Apparently, about 90% of application do not employ this technique, they use
+# max size always: nginx, apache, java stuff. But Golang tools, angie and
+# some specific patches activate this technique.
+#
+# In order to mimic a real website we need to know something about software
+# it uses. Usually nobody cares: openssl does 16384, Python does it, nginx
+# does it. So this setting is disabled by default.
+#
+#      https://blog.cloudflare.com/optimizing-tls-over-tcp-to-reduce-latency/
+#      https://aws.github.io/s2n-tls/usage-guide/ch08-record-sizes.html
+#      https://github.com/cloudflare/sslconfig/blob/master/patches/nginx__dynamic_tls_records.patch
+drs = false
+
 # Some countries do active probing on Telegram connections. This technique
 # allows to protect from such effort.
 #

go.mod

@@ -11,18 +11,18 @@ require (
 	github.com/d4l3k/messagediff v1.2.1 // indirect
 	github.com/jarcoal/httpmock v1.0.8
 	github.com/mccutchen/go-httpbin v1.1.1
-	github.com/panjf2000/ants/v2 v2.11.5
+	github.com/panjf2000/ants/v2 v2.11.6
 	github.com/prometheus/client_golang v1.23.2
 	github.com/prometheus/common v0.67.5 // indirect
-	github.com/prometheus/procfs v0.20.0 // indirect
+	github.com/prometheus/procfs v0.20.1 // indirect
 	github.com/rs/zerolog v1.34.0
 	github.com/smira/go-statsd v1.3.4
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/stretchr/testify v1.11.1
 	github.com/tylertreat/BoomFilters v0.0.0-20251117164519-53813c36cc1b
-	golang.org/x/crypto v0.48.0
-	golang.org/x/net v0.51.0
-	golang.org/x/sys v0.41.0
+	golang.org/x/crypto v0.49.0
+	golang.org/x/net v0.52.0
+	golang.org/x/sys v0.42.0
 	google.golang.org/protobuf v1.36.11 // indirect
 )
 
@@ -49,8 +49,8 @@ require (
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/txthinking/runnergroup v0.0.0-20250224021307-5864ffeb65ae // indirect
-	go.yaml.in/yaml/v2 v2.4.3 // indirect
-	golang.org/x/sync v0.19.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.4 // indirect
+	golang.org/x/sync v0.20.0 // indirect
 	golang.org/x/tools v0.41.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -53,8 +53,8 @@ github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/ncruces/go-dns v1.3.2 h1:kBLuUZBgkQ4qF4WDXZRQ4rG0Gk6sLVJQ5tESkWrxUa0=
 github.com/ncruces/go-dns v1.3.2/go.mod h1:tuzixNY8PY/M7yUzcvRbUaeLs3ifIdydpi5H2bfRU+s=
-github.com/panjf2000/ants/v2 v2.11.5 h1:a7LMnMEeux/ebqTux140tRiaqcFTV0q2bEHF03nl6Rg=
-github.com/panjf2000/ants/v2 v2.11.5/go.mod h1:8u92CYMUc6gyvTIw8Ru7Mt7+/ESnJahz5EVtqfrilek=
+github.com/panjf2000/ants/v2 v2.11.6 h1:JKsoIUukIoCO0sP0gcOqdyoXmpyKXuU6fC57rODtpug=
+github.com/panjf2000/ants/v2 v2.11.6/go.mod h1:8u92CYMUc6gyvTIw8Ru7Mt7+/ESnJahz5EVtqfrilek=
 github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
 github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
@@ -70,8 +70,8 @@ github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNw
 github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
 github.com/prometheus/common v0.67.5 h1:pIgK94WWlQt1WLwAC5j2ynLaBRDiinoAb86HZHTUGI4=
 github.com/prometheus/common v0.67.5/go.mod h1:SjE/0MzDEEAyrdr5Gqc6G+sXI67maCxzaT3A2+HqjUw=
-github.com/prometheus/procfs v0.20.0 h1:AA7aCvjxwAquZAlonN7888f2u4IN8WVeFgBi4k82M4Q=
-github.com/prometheus/procfs v0.20.0/go.mod h1:o9EMBZGRyvDrSPH1RqdxhojkuXstoe4UlK79eF5TGGo=
+github.com/prometheus/procfs v0.20.1 h1:XwbrGOIplXW/AU3YhIhLODXMJYyC1isLFfYCsTEycfc=
+github.com/prometheus/procfs v0.20.1/go.mod h1:o9EMBZGRyvDrSPH1RqdxhojkuXstoe4UlK79eF5TGGo=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/rs/xid v1.6.0/go.mod h1:7XoLgs4eV+QndskICGsho+ADou8ySMSjJKDIan90Nz0=
@@ -105,12 +105,12 @@ github.com/yl2chen/cidranger v1.0.2/go.mod h1:9U1yz7WPYDwf0vpNWFaeRh0bjwz5RVgRy/
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
-go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
+go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
+go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/crypto v0.48.0 h1:/VRzVqiRSggnhY7gNRxPauEQ5Drw9haKdM0jqfcCFts=
-golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=
+golang.org/x/crypto v0.49.0 h1:+Ng2ULVvLHnJ/ZFEq4KdcDd/cfjrrjjNSXNzxg0Y4U4=
+golang.org/x/crypto v0.49.0/go.mod h1:ErX4dUh2UM+CFYiXZRTcMpEcN8b/1gxEuv3nODoYtCA=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.7.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/mod v0.32.0 h1:9F4d3PHLljb6x//jOyokMv3eX+YDeepZSEo3mFJy93c=
@@ -119,13 +119,13 @@ golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
 golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
-golang.org/x/net v0.51.0 h1:94R/GTO7mt3/4wIKpcR5gkGmRLOuE/2hNGeWq/GBIFo=
-golang.org/x/net v0.51.0/go.mod h1:aamm+2QF5ogm02fjy5Bb7CQ0WMt1/WVM7FtyaTLlA9Y=
+golang.org/x/net v0.52.0 h1:He/TN1l0e4mmR3QqHMT2Xab3Aj3L9qjbhRm78/6jrW0=
+golang.org/x/net v0.52.0/go.mod h1:R1MAz7uMZxVMualyPXb+VaqGSa3LIaUqk0eEt3w36Sw=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
-golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
+golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -135,8 +135,8 @@ golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
-golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
+golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=

internal/cli/access.go

@@ -101,8 +101,13 @@ func (a *Access) Run(cli *CLI, version string) error {
 }
 
 func (a *Access) getIP(ntw mtglib.Network, protocol string) net.IP {
+	dialer := ntw.NativeDialer()
 	client := ntw.MakeHTTPClient(func(ctx context.Context, network, address string) (essentials.Conn, error) {
-		return ntw.DialContext(ctx, protocol, address) //nolint: wrapcheck
+		conn, err := dialer.DialContext(ctx, protocol, address)
+		if err != nil {
+			return nil, err
+		}
+		return essentials.WrapNetConn(conn), err
 	})
 
 	req, err := http.NewRequest(http.MethodGet, "https://ifconfig.co", nil) //nolint: noctx

internal/cli/run_proxy.go

@@ -46,13 +46,13 @@ func makeNetwork(conf *config.Config, version string) (mtglib.Network, error) {
 
 	base := network.New(
 		resolver,
-		"mtg/"+version,
+		"",
 		conf.Network.Timeout.TCP.Get(0),
 		conf.Network.Timeout.HTTP.Get(0),
 		conf.Network.Timeout.Idle.Get(0),
 	)
 
-	proxyDialers := make([]network.Network, len(conf.Network.Proxies))
+	proxyDialers := make([]mtglib.Network, len(conf.Network.Proxies))
 	for idx, v := range conf.Network.Proxies {
 		value, err := network.NewProxyNetwork(base, v.Get(nil))
 		if err != nil {
@@ -239,6 +239,11 @@ func runProxy(conf *config.Config, version string) error { //nolint: funlen
 		return fmt.Errorf("cannot build ip allowlist: %w", err)
 	}
 
+	doppelGangerURLs := make([]string, len(conf.Defense.Doppelganger.URLs))
+	for i, v := range conf.Defense.Doppelganger.URLs {
+		doppelGangerURLs[i] = v.String()
+	}
+
 	opts := mtglib.ProxyOpts{
 		Logger:          logger,
 		Network:         ntw,
@@ -256,6 +261,11 @@ func runProxy(conf *config.Config, version string) error { //nolint: funlen
 
 		AllowFallbackOnUnknownDC: conf.AllowFallbackOnUnknownDC.Get(false),
 		TolerateTimeSkewness:     conf.TolerateTimeSkewness.Value,
+
+		DoppelGangerURLs:    doppelGangerURLs,
+		DoppelGangerPerRaid: conf.Defense.Doppelganger.Repeats.Get(mtglib.DoppelGangerPerRaid),
+		DoppelGangerEach:    conf.Defense.Doppelganger.UpdateEach.Get(mtglib.DoppelGangerEach),
+		DoppelGangerDRS:     conf.Defense.Doppelganger.DRS.Get(false),
 	}
 
 	proxy, err := mtglib.NewProxy(opts)

internal/config/config.go

@@ -47,8 +47,14 @@ type Config struct {
 			MaxSize   TypeBytes     `json:"maxSize"`
 			ErrorRate TypeErrorRate `json:"errorRate"`
 		} `json:"antiReplay"`
-		Blocklist ListConfig `json:"blocklist"`
-		Allowlist ListConfig `json:"allowlist"`
+		Blocklist    ListConfig `json:"blocklist"`
+		Allowlist    ListConfig `json:"allowlist"`
+		Doppelganger struct {
+			URLs       []TypeHttpsURL  `json:"urls"`
+			Repeats    TypeConcurrency `json:"repeats_per_raid"`
+			UpdateEach TypeDuration    `json:"raid_each"`
+			DRS        TypeBool        `json:"drs"`
+		} `json:"doppelganger"`
 	} `json:"defense"`
 	Network struct {
 		Timeout struct {

internal/config/parse.go

@@ -44,6 +44,12 @@ type tomlConfig struct {
 			URLs                []string `toml:"urls" json:"urls,omitempty"`
 			UpdateEach          string   `toml:"update-each" json:"updateEach,omitempty"`
 		} `toml:"allowlist" json:"allowlist,omitempty"`
+		Doppelganger struct {
+			URLs       []string `toml:"urls" json:"urls,omitempty"`
+			Repeats    uint     `toml:"repeats-per-raid" json:"repeats_per_raid,omitempty"`
+			UpdateEach string   `toml:"raid-each" json:"raid_each,omitempty"`
+			DRS        bool     `toml:"drs" json:"drs,omitempty"`
+		} `toml:"doppelganger" json:"doppelganger,omitempty"`
 	} `toml:"defense" json:"defense,omitempty"`
 	Network struct {
 		Timeout struct {

internal/config/type_https_url.go

@@ -0,0 +1,53 @@
+package config
+
+import (
+	"fmt"
+	"net/url"
+)
+
+type TypeHttpsURL struct {
+	Value *url.URL
+}
+
+func (t *TypeHttpsURL) Set(value string) error {
+	parsedURL, err := url.Parse(value)
+	if err != nil {
+		return fmt.Errorf("value is not correct URL (%s): %w", value, err)
+	}
+
+	if parsedURL.Host == "" {
+		return fmt.Errorf("url has to have a schema: %s", value)
+	}
+
+	if parsedURL.Scheme != "https" {
+		return fmt.Errorf("unsupported schema: %s", parsedURL.Scheme)
+	}
+
+	t.Value = parsedURL
+
+	return nil
+}
+
+func (t *TypeHttpsURL) Get(defaultValue *url.URL) *url.URL {
+	if t.Value == nil {
+		return defaultValue
+	}
+
+	return t.Value
+}
+
+func (t *TypeHttpsURL) UnmarshalText(data []byte) error {
+	return t.Set(string(data))
+}
+
+func (t TypeHttpsURL) MarshalText() ([]byte, error) {
+	return []byte(t.String()), nil
+}
+
+func (t TypeHttpsURL) String() string {
+	if t.Value == nil {
+		return ""
+	}
+
+	return t.Value.String()
+}

internal/config/type_https_url_test.go

@@ -0,0 +1,100 @@
+package config_test
+
+import (
+	"encoding/json"
+	"net/url"
+	"testing"
+
+	"github.com/9seconds/mtg/v2/internal/config"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+)
+
+type typeHttpsURLTestStruct struct {
+	Value config.TypeHttpsURL `json:"value"`
+}
+
+type HttpsURLTestSuite struct {
+	suite.Suite
+}
+
+func (suite *HttpsURLTestSuite) TestUnmarshalFail() {
+	testData := []string{
+		"",
+		"https://",
+		"://lala",
+		"/path",
+		"http://example.com",
+		"socks5://example.com",
+	}
+
+	for _, v := range testData {
+		data, err := json.Marshal(map[string]string{
+			"value": v,
+		})
+		suite.NoError(err)
+
+		suite.T().Run(v, func(t *testing.T) {
+			assert.Error(t, json.Unmarshal(data, &typeHttpsURLTestStruct{}))
+		})
+	}
+}
+
+func (suite *HttpsURLTestSuite) TestUnmarshalOk() {
+	testData := map[string]string{
+		"https://example.com":           "https://example.com",
+		"https://example.com:8443":      "https://example.com:8443",
+		"https://example.com/path?q=1":  "https://example.com/path?q=1",
+		"https://user:pass@example.com": "https://user:pass@example.com",
+	}
+
+	for k, v := range testData {
+		value := v
+
+		data, err := json.Marshal(map[string]string{
+			"value": k,
+		})
+		suite.NoError(err)
+
+		suite.T().Run(k, func(t *testing.T) {
+			testStruct := &typeHttpsURLTestStruct{}
+			assert.NoError(t, json.Unmarshal(data, testStruct))
+
+			parsed, _ := url.Parse(value)
+
+			assert.Equal(t, parsed.Scheme, testStruct.Value.Get(nil).Scheme)
+			assert.Equal(t, parsed.Host, testStruct.Value.Get(nil).Host)
+			assert.Equal(t, parsed.RawQuery, testStruct.Value.Get(nil).RawQuery)
+			assert.Equal(t, parsed.Path, testStruct.Value.Get(nil).Path)
+		})
+	}
+}
+
+func (suite *HttpsURLTestSuite) TestMarshalOk() {
+	parsed, _ := url.Parse("https://example.com/path?q=1")
+	testStruct := &typeHttpsURLTestStruct{
+		Value: config.TypeHttpsURL{
+			Value: parsed,
+		},
+	}
+
+	encodedJSON, err := json.Marshal(testStruct)
+	suite.NoError(err)
+	suite.JSONEq(`{"value": "https://example.com/path?q=1"}`,
+		string(encodedJSON))
+}
+
+func (suite *HttpsURLTestSuite) TestGet() {
+	emptyURL := &url.URL{}
+
+	value := config.TypeHttpsURL{}
+	suite.Equal(emptyURL, value.Get(emptyURL))
+
+	value.Value = &url.URL{}
+	suite.Equal(value.Value, value.Get(emptyURL))
+}
+
+func TestTypeHttpsURL(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &HttpsURLTestSuite{})
+}

internal/testlib/mtglib_network_mock.go

@@ -2,6 +2,7 @@ package testlib
 
 import (
 	"context"
+	"net"
 	"net/http"
 
 	"github.com/9seconds/mtg/v2/essentials"
@@ -24,6 +25,10 @@ func (m *MtglibNetworkMock) DialContext(ctx context.Context, network, address st
 	return args.Get(0).(essentials.Conn), args.Error(1) //nolint: wrapcheck, forcetypeassert
 }
 
+func (m *MtglibNetworkMock) NativeDialer() *net.Dialer {
+	return m.Called().Get(0).(*net.Dialer)
+}
+
 func (m *MtglibNetworkMock) MakeHTTPClient(dialFunc func(ctx context.Context,
 	network, address string) (essentials.Conn, error),
 ) *http.Client {

mise.lock

@@ -1,11 +1,11 @@
 [[tools.go]]
-version = "1.26.0"
+version = "1.26.1"
 backend = "core:go"
-"platforms.linux-arm64" = { checksum = "sha256:bd03b743eb6eb4193ea3c3fd3956546bf0e3ca5b7076c8226334afe6b75704cd", url = "https://dl.google.com/go/go1.26.0.linux-arm64.tar.gz"}
-"platforms.linux-x64" = { checksum = "sha256:aac1b08a0fb0c4e0a7c1555beb7b59180b05dfc5a3d62e40e9de90cd42f88235", url = "https://dl.google.com/go/go1.26.0.linux-amd64.tar.gz"}
-"platforms.macos-arm64" = { checksum = "sha256:b1640525dfe68f066d56f200bef7bf4dce955a1a893bd061de6754c211431023", url = "https://dl.google.com/go/go1.26.0.darwin-arm64.tar.gz"}
-"platforms.macos-x64" = { checksum = "sha256:1ca28b7703cbea05a65b2a1d92d6b308610ef92f8824578a0874f2e60c9d5a22", url = "https://dl.google.com/go/go1.26.0.darwin-amd64.tar.gz"}
-"platforms.windows-x64" = { checksum = "sha256:9bbe0fc64236b2b51f6255c05c4232532b8ecc0e6d2e00950bd3021d8a4d07d4", url = "https://dl.google.com/go/go1.26.0.windows-amd64.zip"}
+"platforms.linux-arm64" = { checksum = "sha256:a290581cfe4fe28ddd737dde3095f3dbeb7f2e4065cab4eae44dfc53b760c2f7", url = "https://dl.google.com/go/go1.26.1.linux-arm64.tar.gz"}
+"platforms.linux-x64" = { checksum = "sha256:031f088e5d955bab8657ede27ad4e3bc5b7c1ba281f05f245bcc304f327c987a", url = "https://dl.google.com/go/go1.26.1.linux-amd64.tar.gz"}
+"platforms.macos-arm64" = { checksum = "sha256:353df43a7811ce284c8938b5f3c7df40b7bfb6f56cb165b150bc40b5e2dd541f", url = "https://dl.google.com/go/go1.26.1.darwin-arm64.tar.gz"}
+"platforms.macos-x64" = { checksum = "sha256:65773dab2f8cc4cd23d93ba6d0a805de150ca0b78378879292be0b903b8cdd08", url = "https://dl.google.com/go/go1.26.1.darwin-amd64.tar.gz"}
+"platforms.windows-x64" = { checksum = "sha256:9b68112c913f45b7aebbf13c036721264bbba7e03a642f8f7490c561eebd1ecc", url = "https://dl.google.com/go/go1.26.1.windows-amd64.zip"}
 
 [[tools."go:golang.org/x/pkgsite/cmd/pkgsite"]]
 version = "latest"
@@ -24,19 +24,19 @@ version = "0.9.2"
 backend = "go:mvdan.cc/gofumpt"
 
 [[tools.golangci-lint]]
-version = "2.10.1"
+version = "2.11.3"
 backend = "aqua:golangci/golangci-lint"
-"platforms.linux-arm64" = { checksum = "sha256:6652b42ae02915eb2f9cb2a2e0cac99514c8eded8388d88ae3e06e1a52c00de8", url = "https://github.com/golangci/golangci-lint/releases/download/v2.10.1/golangci-lint-2.10.1-linux-arm64.tar.gz"}
-"platforms.linux-x64" = { checksum = "sha256:dfa775874cf0561b404a02a8f4481fc69b28091da95aa697259820d429b09c99", url = "https://github.com/golangci/golangci-lint/releases/download/v2.10.1/golangci-lint-2.10.1-linux-amd64.tar.gz"}
-"platforms.macos-arm64" = { checksum = "sha256:03bfadf67e52b441b7ec21305e501c717df93c959836d66c7f97312654acb297", url = "https://github.com/golangci/golangci-lint/releases/download/v2.10.1/golangci-lint-2.10.1-darwin-arm64.tar.gz"}
-"platforms.macos-x64" = { checksum = "sha256:66fb0da81b8033b477f97eea420d4b46b230ca172b8bb87c6610109f3772b6b6", url = "https://github.com/golangci/golangci-lint/releases/download/v2.10.1/golangci-lint-2.10.1-darwin-amd64.tar.gz"}
-"platforms.windows-x64" = { checksum = "sha256:c60c87695e79db8e320f0e5be885059859de52bb5ee5f11be5577828570bc2a3", url = "https://github.com/golangci/golangci-lint/releases/download/v2.10.1/golangci-lint-2.10.1-windows-amd64.zip"}
+"platforms.linux-arm64" = { checksum = "sha256:ee3d95f301359e7d578e6d99c8ad5aeadbabc5a13009a30b2b0df11c8058afe9", url = "https://github.com/golangci/golangci-lint/releases/download/v2.11.3/golangci-lint-2.11.3-linux-arm64.tar.gz"}
+"platforms.linux-x64" = { checksum = "sha256:87bb8cddbcc825d5778b64e8a91b46c0526b247f4e2f2904dea74ec7450475d1", url = "https://github.com/golangci/golangci-lint/releases/download/v2.11.3/golangci-lint-2.11.3-linux-amd64.tar.gz"}
+"platforms.macos-arm64" = { checksum = "sha256:30ee39979c516b9d1adca289a3f93429d130c4c0fda5e57d637850894221f6cc", url = "https://github.com/golangci/golangci-lint/releases/download/v2.11.3/golangci-lint-2.11.3-darwin-arm64.tar.gz"}
+"platforms.macos-x64" = { checksum = "sha256:f93bda1f2cc981fd1326464020494be62f387bbf262706e1b3b644e5afacc440", url = "https://github.com/golangci/golangci-lint/releases/download/v2.11.3/golangci-lint-2.11.3-darwin-amd64.tar.gz"}
+"platforms.windows-x64" = { checksum = "sha256:cd42e890176bc5cfeb36225a77e66b9410ddd3a59a03551e23f6b210d29e1f67", url = "https://github.com/golangci/golangci-lint/releases/download/v2.11.3/golangci-lint-2.11.3-windows-amd64.zip"}
 
 [[tools.goreleaser]]
-version = "2.14.1"
+version = "2.14.3"
 backend = "aqua:goreleaser/goreleaser"
-"platforms.linux-arm64" = { checksum = "sha256:a84d3b27f052c12ad5c8342d7caf1450a7174a305730aed21d72db09301e49a5", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.1/goreleaser_Linux_arm64.tar.gz"}
-"platforms.linux-x64" = { checksum = "sha256:2df975a7acbfdeaf888d596cab0024d48ec7fb7d747e1d08b90948b791f40a5f", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.1/goreleaser_Linux_x86_64.tar.gz"}
-"platforms.macos-arm64" = { checksum = "sha256:9f2e47f847b4f4177376fc6aa6914fbc7f673f59720076747e738b578c2e896e", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.1/goreleaser_Darwin_all.tar.gz"}
-"platforms.macos-x64" = { checksum = "sha256:9f2e47f847b4f4177376fc6aa6914fbc7f673f59720076747e738b578c2e896e", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.1/goreleaser_Darwin_all.tar.gz"}
-"platforms.windows-x64" = { checksum = "sha256:d7a3d8ba795e97ab8c4f8003630d300da164adf21fde5a4049440c20f15c3137", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.1/goreleaser_Windows_x86_64.zip"}
+"platforms.linux-arm64" = { checksum = "sha256:581a10e53c1176b3e81ee45cf531e02dbf899db0bc7b795669347df4276ce948", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.3/goreleaser_Linux_arm64.tar.gz"}
+"platforms.linux-x64" = { checksum = "sha256:dc7faeeeb6da8bdfda788626263a4ae725892a8c7504b975c3234127d4a44579", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.3/goreleaser_Linux_x86_64.tar.gz"}
+"platforms.macos-arm64" = { checksum = "sha256:3507798489e107a78aff36b169de48148a335ac26eb3161608d905f3f3a957bd", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.3/goreleaser_Darwin_all.tar.gz"}
+"platforms.macos-x64" = { checksum = "sha256:3507798489e107a78aff36b169de48148a335ac26eb3161608d905f3f3a957bd", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.3/goreleaser_Darwin_all.tar.gz"}
+"platforms.windows-x64" = { checksum = "sha256:3deea8ff471aa258a2d99f3e5302971d7028647ae8ddaf103257a8113e485a31", url = "https://github.com/goreleaser/goreleaser/releases/download/v2.14.3/goreleaser_Windows_x86_64.zip"}

mtglib/init.go

@@ -99,6 +99,13 @@ const (
 	// reads from Telegram after which connection will be terminated. This is
 	// required to abort stale connections.
 	TCPRelayReadTimeout = 20 * time.Second
+
+	// DoppelGangerPerRaid defines a number of requests to each URL
+	// per raid.
+	DoppelGangerPerRaid = 10
+
+	// DoppelGangerEach defines a time period between each crawl attempt.
+	DoppelGangerEach = 6 * time.Hour
 )
 
 // Network defines a knowledge how to work with a network. It may sound fun but
@@ -117,13 +124,17 @@ type Network interface {
 	// Dial establishes context-free TCP connections.
 	Dial(network, address string) (essentials.Conn, error)
 
-	// DialContext dials using a context. This is a preferrable way of
+	// DialContext dials using a context. This is a preferable way of
 	// establishing TCP connections.
 	DialContext(ctx context.Context, network, address string) (essentials.Conn, error)
 
 	// MakeHTTPClient build an HTTP client with given dial function. If nothing is
 	// provided, then DialContext of this interface is going to be used.
 	MakeHTTPClient(func(ctx context.Context, network, address string) (essentials.Conn, error)) *http.Client
+
+	// NativeDialer returns a configured instance of native dialer that
+	// skips proxy connections or any other irrelevant settings.
+	NativeDialer() *net.Dialer
 }
 
 // AntiReplayCache is an interface that is used to detect replay attacks based

mtglib/internal/doppel/clock.go

@@ -0,0 +1,35 @@
+package doppel
+
+import (
+	"context"
+	"time"
+)
+
+type Clock struct {
+	stats *Stats
+	tick  chan struct{}
+}
+
+func (c Clock) Start(ctx context.Context) {
+	tickTock := time.NewTimer(c.stats.Delay())
+	defer func() {
+		tickTock.Stop()
+		select {
+		case <-tickTock.C:
+		default:
+		}
+	}()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-tickTock.C:
+			select {
+			case <-ctx.Done():
+			case c.tick <- struct{}{}:
+			}
+			tickTock.Reset(c.stats.Delay())
+		}
+	}
+}

mtglib/internal/doppel/clock_test.go

@@ -0,0 +1,80 @@
+package doppel
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type ClockTestSuite struct {
+	suite.Suite
+
+	clock     Clock
+	wg        sync.WaitGroup
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+}
+
+func (suite *ClockTestSuite) SetupTest() {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	suite.ctx = ctx
+	suite.ctxCancel = cancel
+	suite.clock = Clock{
+		stats: &Stats{
+			k:      StatsDefaultK,
+			lambda: StatsDefaultLambda,
+		},
+		tick: make(chan struct{}),
+	}
+
+	suite.wg.Go(func() {
+		suite.clock.Start(suite.ctx)
+	})
+}
+
+func (suite *ClockTestSuite) TearDownTest() {
+	suite.ctxCancel()
+	suite.wg.Wait()
+}
+
+func (suite *ClockTestSuite) TestTicks() {
+	received := 0
+
+	for range 3 {
+		select {
+		case <-suite.clock.tick:
+			received++
+		case <-time.After(2 * time.Second):
+			suite.Fail("timed out waiting for tick")
+		}
+	}
+
+	suite.Equal(3, received)
+}
+
+func (suite *ClockTestSuite) TestStopsOnCancel() {
+	select {
+	case <-suite.clock.tick:
+	case <-time.After(2 * time.Second):
+		suite.Fail("timed out waiting for first tick")
+	}
+
+	suite.ctxCancel()
+
+	time.Sleep(50 * time.Millisecond)
+
+	select {
+	case <-suite.clock.tick:
+		suite.Fail("received tick after cancel")
+	default:
+	}
+}
+
+func TestClock(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ClockTestSuite{})
+}

mtglib/internal/doppel/conn.go

@@ -0,0 +1,130 @@
+package doppel
+
+import (
+	"bytes"
+	"context"
+	"sync"
+
+	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+)
+
+type Conn struct {
+	essentials.Conn
+
+	p *connPayload
+}
+
+type connPayload struct {
+	ctx           context.Context
+	ctxCancel     context.CancelCauseFunc
+	clock         Clock
+	wg            sync.WaitGroup
+	syncWriteLock sync.RWMutex
+	writeStream   bytes.Buffer
+	writeCond     *sync.Cond
+}
+
+func (c Conn) Write(p []byte) (int, error) {
+	c.p.syncWriteLock.RLock()
+	defer c.p.syncWriteLock.RUnlock()
+
+	c.p.writeCond.L.Lock()
+	c.p.writeStream.Write(p)
+	c.p.writeCond.L.Unlock()
+
+	return len(p), context.Cause(c.p.ctx)
+}
+
+func (c Conn) SyncWrite(p []byte) (int, error) {
+	c.p.syncWriteLock.Lock()
+	defer c.p.syncWriteLock.Unlock()
+
+	c.p.writeCond.L.Lock()
+	// wait until buffer is exhausted
+	for c.p.writeStream.Len() != 0 && context.Cause(c.p.ctx) == nil {
+		c.p.writeCond.Wait()
+	}
+	c.p.writeStream.Write(p)
+	c.p.writeCond.L.Unlock()
+
+	if err := context.Cause(c.p.ctx); err != nil {
+		return len(p), err
+	}
+
+	c.p.writeCond.L.Lock()
+	// wait until data will be sent
+	for c.p.writeStream.Len() != 0 && context.Cause(c.p.ctx) == nil {
+		c.p.writeCond.Wait()
+	}
+	c.p.writeCond.L.Unlock()
+
+	return len(p), context.Cause(c.p.ctx)
+}
+
+func (c Conn) Start() {
+	c.p.wg.Go(func() {
+		c.start()
+	})
+}
+
+func (c Conn) start() {
+	defer c.p.writeCond.Broadcast()
+
+	buf := [tls.MaxRecordSize]byte{}
+
+	for {
+		select {
+		case <-c.p.ctx.Done():
+			return
+		case <-c.p.clock.tick:
+		}
+
+		c.p.writeCond.L.Lock()
+		n, err := c.p.writeStream.Read(buf[:c.p.clock.stats.Size()])
+		c.p.writeCond.L.Unlock()
+
+		if n == 0 || err != nil {
+			continue
+		}
+
+		if err := tls.WriteRecord(c.Conn, buf[:n]); err != nil {
+			c.p.ctxCancel(err)
+			return
+		}
+
+		c.p.writeCond.Signal()
+	}
+}
+
+func (c Conn) Stop() {
+	c.p.ctxCancel(nil)
+	c.p.wg.Wait()
+}
+
+func NewConn(ctx context.Context, conn essentials.Conn, stats *Stats) Conn {
+	ctx, cancel := context.WithCancelCause(ctx)
+	rv := Conn{
+		Conn: conn,
+		p: &connPayload{
+			ctx:       ctx,
+			ctxCancel: cancel,
+			writeCond: sync.NewCond(&sync.Mutex{}),
+			clock: Clock{
+				stats: stats,
+				tick:  make(chan struct{}),
+			},
+		},
+	}
+
+	rv.p.writeStream.Grow(tls.DefaultBufferSize)
+
+	rv.p.wg.Go(func() {
+		rv.p.clock.Start(ctx)
+	})
+	rv.p.wg.Go(func() {
+		rv.start()
+	})
+
+	return rv
+}

mtglib/internal/doppel/conn_test.go

@@ -0,0 +1,293 @@
+package doppel
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"errors"
+	"io"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/9seconds/mtg/v2/internal/testlib"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type ConnMock struct {
+	testlib.EssentialsConnMock
+
+	mu          sync.Mutex
+	writeBuffer bytes.Buffer
+}
+
+func (m *ConnMock) Write(p []byte) (int, error) {
+	args := m.Called(p)
+	if err := args.Error(1); err != nil {
+		return args.Int(0), err
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	return m.writeBuffer.Write(p)
+}
+
+func (m *ConnMock) Written() []byte {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	return bytes.Clone(m.writeBuffer.Bytes())
+}
+
+type ConnTestSuite struct {
+	suite.Suite
+
+	connMock  *ConnMock
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+}
+
+func (suite *ConnTestSuite) SetupTest() {
+	ctx, cancel := context.WithCancel(context.Background())
+	suite.ctx = ctx
+	suite.ctxCancel = cancel
+	suite.connMock = &ConnMock{}
+}
+
+func (suite *ConnTestSuite) TearDownTest() {
+	suite.ctxCancel()
+	suite.connMock.AssertExpectations(suite.T())
+}
+
+func (suite *ConnTestSuite) makeConn() Conn {
+	return NewConn(suite.ctx, suite.connMock, &Stats{
+		k:      2.0,
+		lambda: 0.01,
+	})
+}
+
+func (suite *ConnTestSuite) TestWriteBuffersData() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	defer c.Stop()
+
+	n, err := c.Write([]byte{1, 2, 3})
+	suite.NoError(err)
+	suite.Equal(3, n)
+}
+
+func (suite *ConnTestSuite) TestWriteOutputsTLSRecords() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+
+	payload := []byte("hello doppelganger")
+	_, err := c.Write(payload)
+	suite.NoError(err)
+
+	suite.Eventually(func() bool {
+		return len(suite.connMock.Written()) > 0
+	}, 2*time.Second, time.Millisecond)
+
+	c.Stop()
+
+	assembled := &bytes.Buffer{}
+	reader := bytes.NewReader(suite.connMock.Written())
+
+	for {
+		header := make([]byte, tls.SizeHeader)
+		if _, err := io.ReadFull(reader, header); err != nil {
+			break
+		}
+
+		suite.Equal(byte(tls.TypeApplicationData), header[0])
+		suite.Equal(tls.TLSVersion[:], header[tls.SizeRecordType:tls.SizeRecordType+tls.SizeVersion])
+
+		length := binary.BigEndian.Uint16(header[tls.SizeRecordType+tls.SizeVersion:])
+		suite.Greater(length, uint16(0))
+
+		rec := make([]byte, length)
+		_, err := io.ReadFull(reader, rec)
+		suite.NoError(err)
+
+		assembled.Write(rec)
+	}
+
+	suite.Equal(payload, assembled.Bytes())
+}
+
+func (suite *ConnTestSuite) TestWriteReturnsErrorAfterStop() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	c.Stop()
+
+	time.Sleep(10 * time.Millisecond)
+
+	_, err := c.Write([]byte{1})
+	suite.Error(err)
+}
+
+func (suite *ConnTestSuite) TestStopOnUnderlyingWriteError() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, errors.New("connection reset")).
+		Maybe()
+
+	c := suite.makeConn()
+
+	_, _ = c.Write([]byte("data"))
+
+	suite.Eventually(func() bool {
+		_, err := c.Write([]byte{1})
+		return err != nil
+	}, 2*time.Second, time.Millisecond)
+}
+
+func (suite *ConnTestSuite) TestSyncWriteDataSent() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	defer c.Stop()
+
+	payload := []byte("sync hello")
+	n, err := c.SyncWrite(payload)
+	suite.NoError(err)
+	suite.Equal(len(payload), n)
+
+	// SyncWrite returns only after data is flushed to the wire.
+	assembled := &bytes.Buffer{}
+	reader := bytes.NewReader(suite.connMock.Written())
+
+	for {
+		header := make([]byte, tls.SizeHeader)
+		if _, err := io.ReadFull(reader, header); err != nil {
+			break
+		}
+
+		suite.Equal(byte(tls.TypeApplicationData), header[0])
+
+		length := binary.BigEndian.Uint16(header[tls.SizeRecordType+tls.SizeVersion:])
+		rec := make([]byte, length)
+		_, err := io.ReadFull(reader, rec)
+		suite.NoError(err)
+
+		assembled.Write(rec)
+	}
+
+	suite.Equal(payload, assembled.Bytes())
+}
+
+func (suite *ConnTestSuite) TestSyncWriteDrainsBufferFirst() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	defer c.Stop()
+
+	// Buffer some data via async Write.
+	_, err := c.Write([]byte("first"))
+	suite.NoError(err)
+
+	// SyncWrite must drain "first" before sending "second".
+	n, err := c.SyncWrite([]byte("second"))
+	suite.NoError(err)
+	suite.Equal(6, n)
+
+	// All data should be on the wire now.
+	assembled := &bytes.Buffer{}
+	reader := bytes.NewReader(suite.connMock.Written())
+
+	for {
+		header := make([]byte, tls.SizeHeader)
+		if _, err := io.ReadFull(reader, header); err != nil {
+			break
+		}
+
+		length := binary.BigEndian.Uint16(header[tls.SizeRecordType+tls.SizeVersion:])
+		rec := make([]byte, length)
+		_, err := io.ReadFull(reader, rec)
+		suite.NoError(err)
+
+		assembled.Write(rec)
+	}
+
+	suite.Equal([]byte("firstsecond"), assembled.Bytes())
+}
+
+func (suite *ConnTestSuite) TestSyncWriteBlocksAsyncWrite() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	defer c.Stop()
+
+	// Start SyncWrite — it holds exclusive lock.
+	syncDone := make(chan struct{})
+
+	go func() {
+		defer close(syncDone)
+		c.SyncWrite([]byte("exclusive")) //nolint: errcheck
+	}()
+
+	// Give SyncWrite time to acquire the lock.
+	time.Sleep(10 * time.Millisecond)
+
+	// Async Write should block until SyncWrite completes.
+	writeDone := make(chan struct{})
+
+	go func() {
+		defer close(writeDone)
+		c.Write([]byte("blocked")) //nolint: errcheck
+	}()
+
+	// SyncWrite should finish first.
+	<-syncDone
+
+	select {
+	case <-writeDone:
+		// Write completed after SyncWrite — correct.
+	case <-time.After(2 * time.Second):
+		suite.Fail("async Write did not unblock after SyncWrite completed")
+	}
+}
+
+func (suite *ConnTestSuite) TestSyncWriteReturnsErrorAfterStop() {
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+
+	c := suite.makeConn()
+	c.Stop()
+
+	time.Sleep(10 * time.Millisecond)
+
+	_, err := c.SyncWrite([]byte("too late"))
+	suite.Error(err)
+}
+
+func TestConn(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ConnTestSuite{})
+}

mtglib/internal/doppel/ganger.go

@@ -0,0 +1,184 @@
+package doppel
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/9seconds/mtg/v2/essentials"
+)
+
+const (
+	DoppelGangerMaxDurations  = 4096
+	DoppelGangerScoutRaidEach = 6 * time.Hour
+	DoppelGangerScoutRepeats  = 10
+)
+
+type gangerConnRequest struct {
+	ret     chan<- Conn
+	payload essentials.Conn
+}
+
+type Ganger struct {
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+	logger    Logger
+	wg        sync.WaitGroup
+
+	scout            Scout
+	scoutRaidEach    time.Duration
+	scoutRaidRepeats int
+
+	drs bool
+
+	stats     *Stats
+	durations []time.Duration
+
+	connRequests chan gangerConnRequest
+}
+
+func (g *Ganger) Shutdown() {
+	g.ctxCancel()
+	g.wg.Wait()
+}
+
+func (g *Ganger) Run() {
+	g.wg.Go(func() {
+		g.run()
+	})
+}
+
+func (g *Ganger) NewConn(conn essentials.Conn) (Conn, error) {
+	rvChan := make(chan Conn)
+	req := gangerConnRequest{
+		ret:     rvChan,
+		payload: conn,
+	}
+	defer close(req.ret)
+
+	select {
+	case <-g.ctx.Done():
+		return Conn{}, context.Cause(g.ctx)
+	case g.connRequests <- req:
+	}
+
+	select {
+	case <-g.ctx.Done():
+		return Conn{}, context.Cause(g.ctx)
+	case conn := <-rvChan:
+		return conn, nil
+	}
+}
+
+func (g *Ganger) run() {
+	scoutTicker := time.NewTicker(g.scoutRaidEach)
+	defer func() {
+		scoutTicker.Stop()
+
+		select {
+		case <-scoutTicker.C:
+		default:
+		}
+	}()
+
+	scoutCollectedChan := make(chan []time.Duration)
+	currentScoutCollectedChan := scoutCollectedChan
+
+	updatedStatsChan := make(chan *Stats)
+
+	g.wg.Go(func() {
+		g.runScoutRaid(scoutCollectedChan)
+	})
+
+	for {
+		select {
+		case <-g.ctx.Done():
+			return
+		case durations := <-currentScoutCollectedChan:
+			g.durations = append(g.durations, durations...)
+
+			if len(g.durations) > DoppelGangerMaxDurations {
+				g.durations = g.durations[len(g.durations)-DoppelGangerMaxDurations:]
+			}
+
+			if len(g.durations) < MinDurationsToCalculate {
+				continue
+			}
+
+			currentScoutCollectedChan = nil
+			g.wg.Go(func() {
+				select {
+				case <-g.ctx.Done():
+				case updatedStatsChan <- NewStats(durations, g.drs):
+				}
+			})
+		case stats := <-updatedStatsChan:
+			g.stats = stats
+			currentScoutCollectedChan = scoutCollectedChan
+		case <-scoutTicker.C:
+			g.wg.Go(func() {
+				g.runScoutRaid(scoutCollectedChan)
+			})
+		case req := <-g.connRequests:
+			select {
+			case <-g.ctx.Done():
+			case req.ret <- NewConn(g.ctx, req.payload, g.stats):
+			}
+		}
+	}
+}
+
+func (g *Ganger) runScoutRaid(rvChan chan<- []time.Duration) {
+	durations := []time.Duration{}
+
+	for range g.scoutRaidRepeats {
+		learned, err := g.scout.Learn(g.ctx)
+		if err != nil {
+			g.logger.WarningError("cannot learn", err)
+			continue
+		}
+		durations = append(durations, learned...)
+	}
+
+	select {
+	case <-g.ctx.Done():
+		return
+	case rvChan <- durations:
+	}
+}
+
+func NewGanger(
+	ctx context.Context,
+	network Network,
+	logger Logger,
+	scoutEach time.Duration,
+	scoutRepeats int,
+	urls []string,
+	drs bool,
+) *Ganger {
+	ctx, cancel := context.WithCancel(ctx)
+
+	if scoutEach == 0 {
+		scoutEach = DoppelGangerScoutRaidEach
+	}
+
+	if scoutRepeats == 0 {
+		scoutRepeats = DoppelGangerScoutRepeats
+	}
+
+	return &Ganger{
+		ctx:              ctx,
+		ctxCancel:        cancel,
+		logger:           logger,
+		scoutRaidEach:    scoutEach,
+		scoutRaidRepeats: scoutRepeats,
+		drs:              drs,
+		stats: &Stats{
+			k:      StatsDefaultK,
+			lambda: StatsDefaultLambda,
+			drs:    drs,
+		},
+		scout:        NewScout(network, urls),
+		connRequests: make(chan gangerConnRequest),
+	}
+}

mtglib/internal/doppel/ganger_test.go

@@ -0,0 +1,107 @@
+package doppel
+
+import (
+	"bytes"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/9seconds/mtg/v2/internal/testlib"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type GangerTestSuite struct {
+	TLSServerTestSuite
+
+	log *LoggerMock
+	g   *Ganger
+}
+
+func (suite *GangerTestSuite) SetupTest() {
+	suite.TLSServerTestSuite.SetupTest()
+
+	suite.log = &LoggerMock{}
+	suite.log.
+		On("Info", mock.AnythingOfType("string")).
+		Maybe()
+	suite.log.
+		On("WarningError", mock.AnythingOfType("string"), mock.Anything).
+		Maybe()
+
+	suite.g = NewGanger(suite.ctx, suite.network, suite.log, time.Hour, 1, suite.urls, true)
+	suite.g.Run()
+}
+
+func (suite *GangerTestSuite) TearDownTest() {
+	suite.g.Shutdown()
+
+	suite.log.AssertExpectations(suite.T())
+	suite.TLSServerTestSuite.TearDownTest()
+}
+
+func (suite *GangerTestSuite) TestNewConnAfterShutdown() {
+	suite.g.Shutdown()
+	connMock := &testlib.EssentialsConnMock{}
+
+	_, err := suite.g.NewConn(connMock)
+	suite.Error(err)
+}
+
+func (suite *GangerTestSuite) TestNewConnWhileRunning() {
+	connMock := &testlib.EssentialsConnMock{}
+	connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(0, nil).
+		Maybe()
+	connMock.On("Close").
+		Return(nil).
+		Maybe()
+
+	conn, err := suite.g.NewConn(connMock)
+	suite.NoError(err)
+
+	conn.Stop()
+}
+
+func (suite *GangerTestSuite) TestNewConnWriteProducesTLSRecords() {
+	var (
+		mu  sync.Mutex
+		buf bytes.Buffer
+	)
+
+	connMock := &testlib.EssentialsConnMock{}
+	connMock.On("Write", mock.AnythingOfType("[]uint8")).
+		Run(func(args mock.Arguments) {
+			mu.Lock()
+			buf.Write(args.Get(0).([]byte))
+			mu.Unlock()
+		}).
+		Return(0, nil).
+		Maybe()
+	connMock.On("Close").
+		Return(nil).
+		Maybe()
+
+	conn, err := suite.g.NewConn(connMock)
+	suite.NoError(err)
+
+	payload := bytes.Repeat([]byte("x"), 512)
+	_, err = conn.Write(payload)
+	suite.NoError(err)
+
+	time.Sleep(500 * time.Millisecond)
+	conn.Stop()
+
+	mu.Lock()
+	written := buf.Bytes()
+	mu.Unlock()
+
+	suite.NotEmpty(written)
+}
+
+func TestGanger(t *testing.T) {
+	t.Parallel()
+
+	suite.Run(t, &GangerTestSuite{})
+}

mtglib/internal/doppel/init.go

@@ -0,0 +1,43 @@
+package doppel
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"time"
+
+	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+)
+
+const (
+	// Please see Stats description
+	// https://blog.cloudflare.com/optimizing-tls-over-tcp-to-reduce-latency/
+	// https://github.com/cloudflare/sslconfig/blob/master/patches/nginx__dynamic_tls_records.patch
+	TLSRecordSizeStart = 1450
+	TLSRecordSizeAccel = 4096
+	TLSRecordSizeMax   = 16384 - tls.SizeHeader
+
+	TLSCounterAccelAfter = 40
+	TLSCounterMaxAfter   = TLSCounterAccelAfter + 20
+
+	TLSRecordSizeResetAfter = time.Second
+)
+
+// copypasted from mtglib
+type Network interface {
+	// Dial establishes context-free TCP connections.
+	Dial(network, address string) (essentials.Conn, error)
+
+	// DialContext dials using a context. This is a preferable way of
+	// establishing TCP connections.
+	DialContext(ctx context.Context, network, address string) (essentials.Conn, error)
+
+	// MakeHTTPClient build an HTTP client with given dial function. If nothing is
+	// provided, then DialContext of this interface is going to be used.
+	MakeHTTPClient(func(ctx context.Context, network, address string) (essentials.Conn, error)) *http.Client
+
+	// NativeDialer returns a configured instance of native dialer that
+	// skips proxy connections or any other irrelevant settings.
+	NativeDialer() *net.Dialer
+}

mtglib/internal/doppel/init_test.go

@@ -0,0 +1,107 @@
+package doppel
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"time"
+
+	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type SimpleNetwork struct{}
+
+func (s SimpleNetwork) Dial(network, address string) (essentials.Conn, error) {
+	return s.DialContext(context.Background(), network, address)
+}
+
+func (s SimpleNetwork) DialContext(ctx context.Context, network, address string) (essentials.Conn, error) {
+	d := &net.Dialer{}
+
+	conn, err := d.DialContext(ctx, network, address)
+	if err != nil {
+		return nil, err
+	}
+
+	return conn.(*net.TCPConn), nil
+}
+
+func (s SimpleNetwork) NativeDialer() *net.Dialer {
+	return &net.Dialer{}
+}
+
+func (s SimpleNetwork) MakeHTTPClient(dialFunc func(ctx context.Context, network, address string) (essentials.Conn, error)) *http.Client {
+	if dialFunc == nil {
+		dialFunc = s.DialContext
+	}
+
+	return &http.Client{
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: true, //nolint: gosec
+			},
+			DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+				return dialFunc(ctx, network, address)
+			},
+		},
+	}
+}
+
+type TLSServerTestSuite struct {
+	suite.Suite
+
+	tlsServer *httptest.Server
+	ctx       context.Context
+	ctxCancel context.CancelFunc
+	network   SimpleNetwork
+	urls      []string
+}
+
+func (suite *TLSServerTestSuite) SetupSuite() {
+	suite.tlsServer = httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Header().Add("Hello", "how long")
+
+		if _, err := w.Write([]byte{1, 2, 3}); err != nil {
+			panic(err)
+		}
+
+		time.Sleep(5 * time.Millisecond)
+
+		if _, err := w.Write([]byte{1, 2, 3}); err != nil {
+			panic(err)
+		}
+	}))
+	suite.urls = []string{suite.tlsServer.URL}
+}
+
+func (suite *TLSServerTestSuite) SetupTest() {
+	ctx, cancel := context.WithCancel(context.Background())
+	suite.ctx = ctx
+	suite.ctxCancel = cancel
+}
+
+func (suite *TLSServerTestSuite) TearDownTest() {
+	suite.ctxCancel()
+	suite.tlsServer.CloseClientConnections()
+}
+
+func (suite *TLSServerTestSuite) TearDownSuite() {
+	suite.tlsServer.Close()
+}
+
+type LoggerMock struct {
+	mock.Mock
+}
+
+func (l *LoggerMock) Info(msg string) {
+	l.Called(msg)
+}
+
+func (l *LoggerMock) WarningError(msg string, err error) {
+	l.Called(msg, err)
+}

mtglib/internal/doppel/logger.go

@@ -0,0 +1,6 @@
+package doppel
+
+type Logger interface {
+	Info(msg string)
+	WarningError(msg string, err error)
+}

mtglib/internal/doppel/scout.go

@@ -0,0 +1,105 @@
+package doppel
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+)
+
+type Scout struct {
+	network Network
+	urls    []string
+}
+
+func (s Scout) Learn(ctx context.Context) ([]time.Duration, error) {
+	var durations []time.Duration
+
+	for _, url := range s.urls {
+		learned, err := s.learn(ctx, url)
+		if err != nil {
+			return nil, err
+		}
+
+		durations = append(durations, learned...)
+	}
+
+	return durations, nil
+}
+
+func (s Scout) learn(ctx context.Context, url string) ([]time.Duration, error) {
+	client, results := s.makeClient()
+
+	if !strings.HasPrefix(url, "https://") {
+		return nil, fmt.Errorf("url %s must be https", url)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := client.Do(req)
+	if resp != nil {
+		io.Copy(io.Discard, resp.Body) //nolint: errcheck
+		resp.Body.Close()              //nolint: errcheck
+		client.CloseIdleConnections()
+	}
+
+	if err != nil || len(results.data) == 0 {
+		return nil, err
+	}
+
+	durations := []time.Duration{}
+	lastTimestamp := time.Time{}
+
+	for i, v := range results.data {
+		if v.recordType != tls.TypeApplicationData {
+			continue
+		}
+
+		if lastTimestamp.IsZero() {
+			if i > 0 {
+				lastTimestamp = results.data[i-1].timestamp
+			} else {
+				lastTimestamp = v.timestamp
+			}
+		}
+
+		durations = append(durations, v.timestamp.Sub(lastTimestamp))
+		lastTimestamp = v.timestamp
+	}
+
+	return durations, nil
+}
+
+func (s Scout) makeClient() (*http.Client, *ScoutConnCollected) {
+	dialer := s.network.NativeDialer()
+	collected := NewScoutConnCollected()
+	client := s.network.MakeHTTPClient(func(
+		ctx context.Context,
+		network string,
+		address string,
+	) (essentials.Conn, error) {
+		conn, err := dialer.DialContext(ctx, network, address)
+		if err != nil {
+			return nil, err
+		}
+
+		return NewScoutConn(essentials.WrapNetConn(conn), collected), nil
+	})
+
+	return client, collected
+}
+
+func NewScout(network Network, urls []string) Scout {
+	return Scout{
+		network: network,
+		urls:    urls,
+	}
+}

mtglib/internal/doppel/scout_conn.go

@@ -0,0 +1,57 @@
+package doppel
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+)
+
+type ScoutConn struct {
+	tls.Conn
+
+	results *ScoutConnCollected
+	rawBuf  *bytes.Buffer
+}
+
+func (s ScoutConn) Read(p []byte) (int, error) {
+	buf := &bytes.Buffer{}
+
+	for {
+		if n, err := s.rawBuf.Read(p); err == nil {
+			return n, nil
+		}
+
+		s.rawBuf.Reset()
+
+		recordType, length, err := tls.ReadRecord(s.Conn, buf)
+		if err != nil {
+			return 0, err
+		}
+
+		s.results.Add(recordType)
+		s.rawBuf.Write([]byte{recordType})
+		s.rawBuf.Write(tls.TLSVersion[:])
+
+		if err := binary.Write(s.rawBuf, binary.BigEndian, uint16(length)); err != nil {
+			return 0, err
+		}
+
+		if _, err := io.Copy(s.rawBuf, buf); err != nil {
+			return 0, err
+		}
+	}
+}
+
+func NewScoutConn(conn essentials.Conn, results *ScoutConnCollected) ScoutConn {
+	rawBuf := &bytes.Buffer{}
+	rawBuf.Grow(tls.MaxRecordSize)
+
+	return ScoutConn{
+		Conn:    tls.New(conn, false, false),
+		results: results,
+		rawBuf:  rawBuf,
+	}
+}

mtglib/internal/doppel/scout_conn_collected.go

@@ -0,0 +1,29 @@
+package doppel
+
+import "time"
+
+const (
+	ScoutConnCollectedPreallocSize = 100
+)
+
+type ScoutConnResult struct {
+	timestamp  time.Time
+	recordType byte
+}
+
+type ScoutConnCollected struct {
+	data []ScoutConnResult
+}
+
+func (s *ScoutConnCollected) Add(record byte) {
+	s.data = append(s.data, ScoutConnResult{
+		timestamp:  time.Now(),
+		recordType: record,
+	})
+}
+
+func NewScoutConnCollected() *ScoutConnCollected {
+	return &ScoutConnCollected{
+		data: make([]ScoutConnResult, 0, ScoutConnCollectedPreallocSize),
+	}
+}

mtglib/internal/doppel/scout_conn_collected_test.go

@@ -0,0 +1,42 @@
+package doppel
+
+import (
+	"testing"
+	"time"
+
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"github.com/stretchr/testify/suite"
+)
+
+type ScoutConnCollectedTestSuite struct {
+	suite.Suite
+}
+
+func (suite *ScoutConnCollectedTestSuite) TestAddSingle() {
+	collected := NewScoutConnCollected()
+	collected.Add(tls.TypeApplicationData)
+
+	suite.Len(collected.data, 1)
+	suite.Equal(byte(tls.TypeApplicationData), collected.data[0].recordType)
+}
+
+func (suite *ScoutConnCollectedTestSuite) TestAddTimestampsAreMonotonic() {
+	collected := NewScoutConnCollected()
+
+	collected.Add(tls.TypeApplicationData)
+
+	time.Sleep(time.Microsecond)
+	collected.Add(tls.TypeApplicationData)
+
+	time.Sleep(time.Microsecond)
+	collected.Add(tls.TypeApplicationData)
+
+	for i := 1; i < len(collected.data); i++ {
+		suite.True(collected.data[i].timestamp.After(collected.data[i-1].timestamp))
+	}
+}
+
+func TestScoutConnCollected(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ScoutConnCollectedTestSuite{})
+}

mtglib/internal/doppel/scout_test.go

@@ -0,0 +1,39 @@
+package doppel
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type ScoutTestSuite struct {
+	TLSServerTestSuite
+
+	scout Scout
+}
+
+func (suite *ScoutTestSuite) SetupSuite() {
+	suite.TLSServerTestSuite.SetupSuite()
+
+	suite.scout = Scout{
+		network: suite.network,
+		urls:    suite.urls,
+	}
+}
+
+func (suite *ScoutTestSuite) TestCollectResults() {
+	durations, err := suite.scout.Learn(suite.ctx)
+	suite.NoError(err)
+	suite.Less(3, len(durations))
+}
+
+func (suite *ScoutTestSuite) TestCollectNothing() {
+	suite.ctxCancel()
+
+	_, err := suite.scout.Learn(suite.ctx)
+	suite.Error(err)
+}
+
+func TestScout(t *testing.T) {
+	suite.Run(t, &ScoutTestSuite{})
+}

mtglib/internal/doppel/stats.go

@@ -0,0 +1,170 @@
+package doppel
+
+import (
+	"math"
+	"math/rand/v2"
+	"time"
+)
+
+const (
+	StatsBisectTimes = 70
+	StatsLowK        = 0.01
+	StatsHighK       = 10.0
+
+	// do not calculate statistics if we have < than this number of durations
+	MinDurationsToCalculate = 100
+
+	// these values are taken from ok.ru. measured from moscow site.
+	StatsDefaultK      = 0.37846373895785335
+	StatsDefaultLambda = 1.73177086015485
+
+	// how many bytes should we drift
+	DRSNoise = 100
+)
+
+// Stats is responsible for generating values that are distributed according
+// to some statistical distribution.
+//
+// It follows several ideas:
+//  1. Based on nginx and Cloudflare behaviour, even if server is eager
+//     to send a lot, they all start with small TLS packets that are
+//     approximately MTU-sized. After
+//  2. After ~40 TLS records, server considers TCP session as somewhat solid
+//     and reliable and ramps up to 4096.
+//  3. After ~20 TLS records more it jumps to the max 16384 bytes and keep
+//     this size as long as it can
+//  4. If there is no any byte within a connection for a longer time period,
+//     this counter resets.
+//
+// This is called Dynamic TLS Record Sizing
+//   - https://blog.cloudflare.com/optimizing-tls-over-tcp-to-reduce-latency/
+//   - https://community.f5.com/kb/technicalarticles/boosting-tls-performance-with-dynamic-record-sizing-on-big-ip/280798
+//   - https://www.igvita.com/2013/10/24/optimizing-tls-record-size-and-buffering-latency/
+//
+// And this optimized for the very first byte, so web browsers could start to
+// render as early as possible, showing user some preliminary results, optimizing
+// for perceived latency.
+//
+// Since this is very typical for the website, we also aim for that.
+//
+// Another important idea is how delays between TLS packets are distributed.
+// In case of sending huge heavy content with max sized record, delays have
+// lognormal distribution. But a nature of a typical website shows that
+// it eagers to deliver as fast as it can in a few very first records and
+// could possibly slow down later.
+//
+// This is perfectly described by Weibull distribution:
+//   - https://en.wikipedia.org/wiki/Weibull_distribution
+//   - https://ieeexplore.ieee.org/document/6662948
+//   - https://www.researchgate.net/publication/224621285_Traffic_modelling_and_cost_optimization_for_transmitting_traffic_messages_over_a_hybrid_broadcast_and_cellular_network
+//   - https://ir.uitm.edu.my/id/eprint/105386/1/105386.pdf
+//
+// In other word, a combination of Dynamic TLS Record Sizing hints us for
+// Weibull distribution.
+//
+// But we also have to keep in mind that DRS is not well spread yet. In most cases
+// users still rely on OpenSSL or webserver defaults. OpenSSL chunks with
+// biggest packet sizes, nginx relies on static setting that is 16k by default.
+// Thus, dynamic sizing has to be present but we cannot oblige users to use that.
+type Stats struct {
+	sizeLastRequested time.Time
+	sizeCounter       int
+
+	// https://en.wikipedia.org/wiki/Shape_parameter
+	k float64
+	// https://en.wikipedia.org/wiki/Scale_parameter
+	lambda float64
+
+	// Dynamic Record Sizing
+	drs bool
+}
+
+func (d *Stats) Delay() time.Duration {
+	// u ∈ (0, 1], avoids ln(0)
+	u := 1.0 - rand.Float64()
+
+	// X = λ·(-ln U)^(1/k)
+	generated := d.lambda * math.Pow(-math.Log(u), 1.0/d.k)
+
+	// generated is in milliseconds
+	return time.Duration(generated * float64(time.Millisecond))
+}
+
+func (d *Stats) Size() int {
+	if time.Since(d.sizeLastRequested) > TLSRecordSizeResetAfter {
+		d.sizeCounter = 0
+	}
+
+	if !d.drs {
+		return TLSRecordSizeMax
+	}
+
+	d.sizeLastRequested = time.Now()
+	d.sizeCounter++
+
+	switch {
+	case d.sizeCounter <= TLSCounterAccelAfter:
+		return TLSRecordSizeStart - rand.IntN(DRSNoise)
+	case d.sizeCounter <= TLSCounterMaxAfter:
+		return TLSRecordSizeAccel - rand.IntN(DRSNoise)
+	}
+
+	return TLSRecordSizeMax
+}
+
+func NewStats(durations []time.Duration, drs bool) *Stats {
+	n := float64(len(durations))
+
+	// in milliseconds
+	durFloats := make([]float64, len(durations))
+	for i, v := range durations {
+		durFloats[i] = float64(v.Microseconds()) / 1000.0
+	}
+
+	// The bisection solves the standard Weibull MLE equation for shape
+	// parameter k. There is no any good formula for doing that so we
+	// approximate it by several bisections. The number of operations
+	// is statically defined by a constant.
+
+	sumLog := 0.0
+	for _, v := range durFloats {
+		sumLog += math.Log(v)
+	}
+
+	lowK := StatsLowK
+	highK := StatsHighK
+
+	for range StatsBisectTimes {
+		midK := (lowK + highK) / 2.0
+		sumXK := 0.0
+		sumXKLog := 0.0
+
+		for _, v := range durFloats {
+			xk := math.Pow(v, midK)
+			sumXK += xk
+			sumXKLog += xk * math.Log(v)
+		}
+
+		if (1.0/midK)+(sumLog/n)-(sumXKLog/sumXK) > 0 {
+			lowK = midK
+		} else {
+			highK = midK
+		}
+	}
+
+	k := (lowK + highK) / 2
+
+	sumXK := 0.0
+	for _, v := range durFloats {
+		sumXK += math.Pow(v, k)
+	}
+
+	// λ = (Σxᵢᵏ / n)^(1/k)
+	lambda := math.Pow(sumXK/n, 1.0/k)
+
+	return &Stats{
+		k:      k,
+		lambda: lambda,
+		drs:    drs,
+	}
+}

mtglib/internal/doppel/stats_test.go

@@ -0,0 +1,219 @@
+package doppel
+
+import (
+	"math"
+	"math/rand/v2"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type StatsTestSuite struct {
+	suite.Suite
+}
+
+func (suite *StatsTestSuite) GenWeibull(k, lambda float64, n int, seed uint64) []time.Duration {
+	rng := rand.New(rand.NewPCG(seed, 0))
+	samples := make([]time.Duration, n)
+
+	for i := range samples {
+		u := 1.0 - rng.Float64()
+		ms := lambda * math.Pow(-math.Log(u), 1.0/k)
+		d := time.Duration(ms * float64(time.Millisecond))
+
+		if d < time.Microsecond {
+			time.Sleep(time.Microsecond)
+			d = time.Microsecond
+		}
+
+		samples[i] = d
+	}
+
+	return samples
+}
+
+func (suite *StatsTestSuite) TestNewStatsRecoverParameters() {
+	knownK := 1.5
+	knownLambda := 100.0
+
+	samples := suite.GenWeibull(knownK, knownLambda, 5000, 42)
+	stats := NewStats(samples, true)
+
+	suite.InDelta(knownK, stats.k, 0.1)
+	suite.InDelta(knownLambda, stats.lambda, 5.0)
+}
+
+func (suite *StatsTestSuite) TestNewStatsExponentialCase() {
+	// When k=1, Weibull reduces to exponential distribution.
+	knownK := 1.0
+	knownLambda := 50.0
+
+	samples := suite.GenWeibull(knownK, knownLambda, 5000, 123)
+	stats := NewStats(samples, true)
+
+	suite.InDelta(knownK, stats.k, 0.1)
+	suite.InDelta(knownLambda, stats.lambda, 5.0)
+}
+
+func (suite *StatsTestSuite) TestNewStatsSmallK() {
+	// k < 1 produces a heavy-tailed distribution typical for network delays.
+	// Lambda must be large enough so samples stay above microsecond precision
+	// after time.Duration round-trip.
+	knownK := 0.6
+	knownLambda := 100.0
+
+	samples := suite.GenWeibull(knownK, knownLambda, 10000, 99)
+	stats := NewStats(samples, true)
+
+	suite.InDelta(knownK, stats.k, 0.05)
+	suite.InDelta(knownLambda, stats.lambda, 5.0)
+}
+
+func (suite *StatsTestSuite) TestNewStatsLargeK() {
+	// k > 1: light tail, concentrated around the mode.
+	knownK := 5.0
+	knownLambda := 200.0
+
+	samples := suite.GenWeibull(knownK, knownLambda, 5000, 77)
+	stats := NewStats(samples, true)
+
+	suite.InDelta(knownK, stats.k, 0.3)
+	suite.InDelta(knownLambda, stats.lambda, 5.0)
+}
+
+func (suite *StatsTestSuite) TestDelayNonNegative() {
+	stats := &Stats{
+		k:      1.5,
+		lambda: 100.0,
+	}
+
+	for range 200 {
+		dur := stats.Delay()
+		suite.GreaterOrEqual(dur, time.Duration(0))
+	}
+}
+
+func (suite *StatsTestSuite) TestDelayDistributionMean() {
+	// Weibull mean = λ · Γ(1 + 1/k)
+	k := 2.0
+	lambda := 50.0
+	stats := &Stats{k: k, lambda: lambda}
+
+	n := 50000
+	sum := 0.0
+
+	for range n {
+		dur := stats.Delay()
+		sum += float64(dur) / float64(time.Millisecond)
+	}
+
+	sampleMean := sum / float64(n)
+	expectedMean := lambda * math.Gamma(1.0+1.0/k)
+
+	suite.InDelta(expectedMean, sampleMean, expectedMean*0.05)
+}
+
+func (suite *StatsTestSuite) TestNewStatsRoundTrip() {
+	// Estimate parameters from data, then verify that Delay samples
+	// from the fitted distribution have approximately the same mean.
+	knownK := 1.2
+	knownLambda := 80.0
+
+	samples := suite.GenWeibull(knownK, knownLambda, 5000, 555)
+	stats := NewStats(samples, true)
+
+	n := 50000
+	sum := 0.0
+
+	for range n {
+		dur := stats.Delay()
+		sum += float64(dur) / float64(time.Millisecond)
+	}
+
+	sampleMean := sum / float64(n)
+	expectedMean := knownLambda * math.Gamma(1.0+1.0/knownK)
+
+	suite.InDelta(expectedMean, sampleMean, expectedMean*0.05)
+}
+
+func (suite *StatsTestSuite) TestSizeStartPhase() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: true}
+
+	for range TLSCounterAccelAfter {
+		size := stats.Size()
+		suite.GreaterOrEqual(size, TLSRecordSizeStart-DRSNoise)
+		suite.LessOrEqual(size, TLSRecordSizeStart)
+	}
+}
+
+func (suite *StatsTestSuite) TestSizeAccelPhase() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: true}
+
+	for range TLSCounterAccelAfter {
+		stats.Size()
+	}
+
+	for range TLSCounterMaxAfter - TLSCounterAccelAfter {
+		size := stats.Size()
+		suite.GreaterOrEqual(size, TLSRecordSizeAccel-DRSNoise)
+		suite.LessOrEqual(size, TLSRecordSizeAccel)
+	}
+}
+
+func (suite *StatsTestSuite) TestSizeMaxPhase() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: true}
+
+	for range TLSCounterMaxAfter {
+		stats.Size()
+	}
+
+	for range 20 {
+		size := stats.Size()
+		suite.Equal(TLSRecordSizeMax, size)
+	}
+}
+
+func (suite *StatsTestSuite) TestSizeResetsAfterInactivity() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: true}
+
+	// Advance past start phase.
+	for range TLSCounterMaxAfter {
+		stats.Size()
+	}
+
+	suite.Equal(TLSRecordSizeMax, stats.Size())
+
+	// Simulate inactivity by backdating sizeLastRequested.
+	stats.sizeLastRequested = time.Now().Add(-TLSRecordSizeResetAfter - time.Millisecond)
+
+	size := stats.Size()
+	suite.GreaterOrEqual(size, TLSRecordSizeStart-DRSNoise)
+	suite.LessOrEqual(size, TLSRecordSizeStart)
+}
+
+func (suite *StatsTestSuite) TestSizeNoDRSAlwaysMax() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: false}
+
+	for range TLSCounterMaxAfter + 20 {
+		suite.Equal(TLSRecordSizeMax, stats.Size())
+	}
+}
+
+func (suite *StatsTestSuite) TestSizeNoDRSIgnoresCounter() {
+	stats := &Stats{k: 1.0, lambda: 1.0, drs: false}
+
+	// Even after many calls, always returns max.
+	for range 200 {
+		suite.Equal(TLSRecordSizeMax, stats.Size())
+	}
+
+	// Inactivity has no effect either.
+	stats.sizeLastRequested = time.Now().Add(-TLSRecordSizeResetAfter - time.Millisecond)
+	suite.Equal(TLSRecordSizeMax, stats.Size())
+}
+
+func TestStats(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &StatsTestSuite{})
+}

mtglib/internal/faketls/client_hello.go

@@ -1,134 +0,0 @@
-package faketls
-
-import (
-	"crypto/hmac"
-	"crypto/sha256"
-	"crypto/subtle"
-	"encoding/binary"
-	"fmt"
-	"time"
-
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-)
-
-type ClientHello struct {
-	Time        time.Time
-	Random      [RandomLen]byte
-	SessionID   []byte
-	Host        string
-	CipherSuite uint16
-}
-
-func (c ClientHello) Valid(hostname string, tolerateTimeSkewness time.Duration) error {
-	if c.Host != "" && c.Host != hostname {
-		return fmt.Errorf("incorrect hostname %s", hostname)
-	}
-
-	now := time.Now()
-
-	timeDiff := now.Sub(c.Time)
-	if timeDiff < 0 {
-		timeDiff = -timeDiff
-	}
-
-	if timeDiff > tolerateTimeSkewness {
-		return fmt.Errorf("incorrect timestamp. got=%d, now=%d, diff=%s",
-			c.Time.Unix(), now.Unix(), timeDiff.String())
-	}
-
-	return nil
-}
-
-func ParseClientHello(secret, handshake []byte) (ClientHello, error) {
-	hello := ClientHello{}
-
-	if len(handshake) < ClientHelloMinLen {
-		return hello, fmt.Errorf("lengh of handshake is too small: %d", len(handshake))
-	}
-
-	if handshake[0] != HandshakeTypeClient {
-		return hello, fmt.Errorf("unknown handshake type %#x", handshake[0])
-	}
-
-	handshakeSizeBytes := [4]byte{0, handshake[1], handshake[2], handshake[3]}
-	handshakeLength := binary.BigEndian.Uint32(handshakeSizeBytes[:])
-
-	if len(handshake)-4 != int(handshakeLength) {
-		return hello,
-			fmt.Errorf("incorrect handshake size. manifested=%d, real=%d",
-				handshakeLength, len(handshake)-4)
-	}
-
-	copy(hello.Random[:], handshake[ClientHelloRandomOffset:])
-	copy(handshake[ClientHelloRandomOffset:], clientHelloEmptyRandom)
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	rec.Type = record.TypeHandshake
-	rec.Version = record.Version10
-	rec.Payload.Write(handshake)
-
-	// mac is calculated for the whole record, not only
-	// for the payload part
-	mac := hmac.New(sha256.New, secret)
-	rec.Dump(mac) //nolint: errcheck
-
-	computedRandom := mac.Sum(nil)
-
-	for i := range RandomLen {
-		computedRandom[i] ^= hello.Random[i]
-	}
-
-	if subtle.ConstantTimeCompare(clientHelloEmptyRandom[:RandomLen-4], computedRandom[:RandomLen-4]) != 1 {
-		return hello, ErrBadDigest
-	}
-
-	timestamp := int64(binary.LittleEndian.Uint32(computedRandom[RandomLen-4:]))
-	hello.Time = time.Unix(timestamp, 0)
-
-	parseSessionID(&hello, handshake)
-	parseCipherSuite(&hello, handshake)
-	parseSNI(&hello, handshake)
-
-	return hello, nil
-}
-
-func parseSessionID(hello *ClientHello, handshake []byte) {
-	hello.SessionID = make([]byte, handshake[ClientHelloSessionIDOffset])
-	copy(hello.SessionID, handshake[ClientHelloSessionIDOffset+1:])
-}
-
-func parseCipherSuite(hello *ClientHello, handshake []byte) {
-	cipherSuiteOffset := ClientHelloSessionIDOffset + len(hello.SessionID) + 3
-	hello.CipherSuite = binary.BigEndian.Uint16(handshake[cipherSuiteOffset : cipherSuiteOffset+2])
-}
-
-func parseSNI(hello *ClientHello, handshake []byte) {
-	cipherSuiteOffset := ClientHelloSessionIDOffset + len(hello.SessionID) + 1
-	handshake = handshake[cipherSuiteOffset:]
-
-	cipherSuiteLength := binary.BigEndian.Uint16(handshake[:2])
-	handshake = handshake[2+cipherSuiteLength:]
-
-	compressionMethodsLength := int(handshake[0])
-	handshake = handshake[1+compressionMethodsLength:]
-
-	extensionsLength := binary.BigEndian.Uint16(handshake[:2])
-	handshake = handshake[2 : 2+extensionsLength]
-
-	for len(handshake) > 0 {
-		if binary.BigEndian.Uint16(handshake[:2]) != ExtensionSNI {
-			extensionsLength := binary.BigEndian.Uint16(handshake[2:4])
-			handshake = handshake[4+extensionsLength:]
-
-			continue
-		}
-
-		hostnameLength := binary.BigEndian.Uint16(handshake[7:9])
-		handshake = handshake[9:]
-		hello.Host = string(handshake[:int(hostnameLength)])
-
-		return
-	}
-}

mtglib/internal/faketls/client_hello_fuzz_test.go

@@ -1,21 +0,0 @@
-package faketls_test
-
-import (
-	"testing"
-
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
-	"github.com/stretchr/testify/require"
-)
-
-var FuzzClientHelloSecret = []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
-
-func FuzzClientHello(f *testing.F) {
-	f.Add([]byte{1, 2, 3})
-
-	f.Fuzz(func(t *testing.T, frame []byte) {
-		_, err := faketls.ParseClientHello(FuzzClientHelloSecret, frame)
-
-		// a probability of having != err is almost negligible
-		require.Error(t, err)
-	})
-}

mtglib/internal/faketls/client_hello_test.go

@@ -1,191 +0,0 @@
-package faketls_test
-
-import (
-	"encoding/base64"
-	"encoding/json"
-	"os"
-	"path/filepath"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/9seconds/mtg/v2/mtglib"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/suite"
-)
-
-type ClientHelloSnapshot struct {
-	Time        int    `json:"time"`
-	Random      string `json:"random"`
-	SessionID   string `json:"sessionId"`
-	Host        string `json:"host"`
-	CipherSuite int    `json:"cipherSuite"`
-	Full        string `json:"full"`
-}
-
-func (c ClientHelloSnapshot) GetTime() time.Time {
-	return time.Unix(int64(c.Time), 0)
-}
-
-func (c ClientHelloSnapshot) GetRandom() []byte {
-	data, _ := base64.StdEncoding.DecodeString(c.Random)
-
-	return data
-}
-
-func (c ClientHelloSnapshot) GetSessionID() []byte {
-	data, _ := base64.StdEncoding.DecodeString(c.SessionID)
-
-	return data
-}
-
-func (c ClientHelloSnapshot) GetHost() string {
-	return c.Host
-}
-
-func (c ClientHelloSnapshot) GetCipherSuite() uint16 {
-	return uint16(c.CipherSuite)
-}
-
-func (c ClientHelloSnapshot) GetFull() []byte {
-	data, _ := base64.StdEncoding.DecodeString(c.Full)
-
-	return data
-}
-
-type ClientHelloTestSuite struct {
-	suite.Suite
-
-	secret mtglib.Secret
-}
-
-func (suite *ClientHelloTestSuite) SetupSuite() {
-	parsed, err := mtglib.ParseSecret("ee367a189aee18fa31c190054efd4a8e9573746f726167652e676f6f676c65617069732e636f6d")
-	if err != nil {
-		panic(err)
-	}
-
-	suite.secret = parsed
-}
-
-func (suite *ClientHelloTestSuite) TestEmptyHandshake() {
-	_, err := faketls.ParseClientHello(suite.secret.Key[:], nil)
-	suite.Error(err)
-}
-
-func (suite *ClientHelloTestSuite) TestIncorrectHandshakeType() {
-	data := make([]byte, 1024)
-	data[0] = 0x02
-
-	_, err := faketls.ParseClientHello(suite.secret.Key[:], data)
-	suite.Error(err)
-}
-
-func (suite *ClientHelloTestSuite) TestIncorrectLength() {
-	data := make([]byte, 1024)
-	data[0] = 0x01
-	data[1] = 0xff
-	data[2] = 0xff
-
-	_, err := faketls.ParseClientHello(suite.secret.Key[:], data)
-	suite.Error(err)
-}
-
-func (suite *ClientHelloTestSuite) TestSnapshotOk() {
-	files, err := os.ReadDir("testdata")
-	suite.NoError(err)
-
-	testData := []string{}
-
-	for _, v := range files {
-		if strings.HasPrefix(v.Name(), "client-hello-ok") {
-			testData = append(testData, v.Name())
-		}
-	}
-
-	for _, name := range testData {
-		path := filepath.Join("testdata", name)
-
-		suite.T().Run(name, func(t *testing.T) {
-			fileData, err := os.ReadFile(path)
-			assert.NoError(t, err)
-
-			snapshot := &ClientHelloSnapshot{}
-			assert.NoError(t, json.Unmarshal(fileData, snapshot))
-
-			hello, err := faketls.ParseClientHello(suite.secret.Key[:], snapshot.GetFull())
-			assert.NoError(t, err)
-			assert.WithinDuration(t, snapshot.GetTime(), hello.Time, time.Second)
-			assert.Equal(t, snapshot.GetRandom(), hello.Random[:])
-			assert.Equal(t, snapshot.GetSessionID(), hello.SessionID)
-			assert.Equal(t, snapshot.GetHost(), hello.Host)
-			assert.Equal(t, snapshot.GetCipherSuite(), hello.CipherSuite)
-		})
-	}
-}
-
-func (suite *ClientHelloTestSuite) TestSnapshotBad() {
-	files, err := os.ReadDir("testdata")
-	suite.NoError(err)
-
-	testData := []string{}
-
-	for _, v := range files {
-		if strings.HasPrefix(v.Name(), "client-hello-bad") {
-			testData = append(testData, v.Name())
-		}
-	}
-
-	for _, name := range testData {
-		path := filepath.Join("testdata", name)
-
-		suite.T().Run(name, func(t *testing.T) {
-			fileData, err := os.ReadFile(path)
-			assert.NoError(t, err)
-
-			snapshot := &ClientHelloSnapshot{}
-			assert.NoError(t, json.Unmarshal(fileData, snapshot))
-
-			_, err = faketls.ParseClientHello(suite.secret.Key[:], snapshot.GetFull())
-			assert.Error(t, err)
-		})
-	}
-}
-
-func (suite *ClientHelloTestSuite) TestValidateHostname() {
-	hello := faketls.ClientHello{
-		Time: time.Now(),
-	}
-	suite.NoError(hello.Valid("hostname", time.Second))
-
-	hello.Host = "hostname"
-	suite.Error(hello.Valid("hostname2", time.Second))
-	suite.NoError(hello.Valid("hostname", time.Second))
-}
-
-func (suite *ClientHelloTestSuite) TestValidateTime() {
-	testData := []time.Duration{
-		-2 * time.Second,
-		2 * time.Second,
-	}
-
-	for _, v := range testData {
-		value := v
-
-		suite.T().Run(value.String(), func(t *testing.T) {
-			hello := faketls.ClientHello{
-				Host: "hostname",
-				Time: time.Now().Add(value),
-			}
-			suite.Error(hello.Valid("hostname", 500*time.Millisecond))
-			suite.Error(hello.Valid("hostname", time.Second))
-			suite.NoError(hello.Valid("hostname", 3*time.Second))
-		})
-	}
-}
-
-func TestClientHello(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &ClientHelloTestSuite{})
-}

mtglib/internal/faketls/conn.go

@@ -1,72 +0,0 @@
-package faketls
-
-import (
-	"bytes"
-	"fmt"
-	"math/rand/v2"
-
-	"github.com/9seconds/mtg/v2/essentials"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-)
-
-type Conn struct {
-	essentials.Conn
-
-	readBuffer bytes.Buffer
-}
-
-func (c *Conn) Read(p []byte) (int, error) {
-	if n, _ := c.readBuffer.Read(p); n > 0 {
-		return n, nil
-	}
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	for {
-		if err := rec.Read(c.Conn); err != nil {
-			return 0, err //nolint: wrapcheck
-		}
-
-		switch rec.Type { //nolint: exhaustive
-		case record.TypeApplicationData:
-			rec.Payload.WriteTo(&c.readBuffer) //nolint: errcheck
-
-			return c.readBuffer.Read(p) //nolint: wrapcheck
-		case record.TypeChangeCipherSpec:
-		default:
-			return 0, fmt.Errorf("unsupported record type %v", rec.Type)
-		}
-	}
-}
-
-func (c *Conn) Write(p []byte) (int, error) {
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	rec.Type = record.TypeApplicationData
-	rec.Version = record.Version12
-
-	written := 0
-
-	for len(p) > 0 {
-		chunkSize := rand.IntN(record.TLSMaxRecordSize)
-		if chunkSize > len(p) || chunkSize == 0 {
-			chunkSize = len(p)
-		}
-
-		rec.Payload.Reset()
-		rec.Payload.Write(p[:chunkSize])
-
-		err := rec.Dump(c.Conn)
-		written += chunkSize
-
-		if err != nil {
-			return written, err
-		}
-
-		p = p[chunkSize:]
-	}
-
-	return written, nil
-}

mtglib/internal/faketls/conn_test.go

@@ -1,153 +0,0 @@
-package faketls_test
-
-import (
-	"bytes"
-	"crypto/rand"
-	"errors"
-	"io"
-	"testing"
-
-	"github.com/9seconds/mtg/v2/internal/testlib"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-	"github.com/stretchr/testify/mock"
-	"github.com/stretchr/testify/suite"
-)
-
-type ConnMock struct {
-	testlib.EssentialsConnMock
-
-	readBuffer  bytes.Buffer
-	writeBuffer bytes.Buffer
-}
-
-func (m *ConnMock) Read(p []byte) (int, error) {
-	m.Called(p)
-
-	return m.readBuffer.Read(p) //nolint: wrapcheck
-}
-
-func (m *ConnMock) Write(p []byte) (int, error) {
-	m.Called(p)
-
-	return m.writeBuffer.Write(p) //nolint: wrapcheck
-}
-
-type ConnTestSuite struct {
-	suite.Suite
-
-	connMock *ConnMock
-	c        *faketls.Conn
-}
-
-func (suite *ConnTestSuite) SetupTest() {
-	suite.connMock = &ConnMock{}
-	suite.c = &faketls.Conn{
-		Conn: suite.connMock,
-	}
-}
-
-func (suite *ConnTestSuite) TearDownTest() {
-	suite.connMock.AssertExpectations(suite.T())
-}
-
-func (suite *ConnTestSuite) TestRead() {
-	suite.connMock.On("Read", mock.Anything).Return(0, nil)
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	rec.Type = record.TypeChangeCipherSpec
-	rec.Version = record.Version12
-
-	rec.Payload.WriteByte(0x01)
-	rec.Dump(&suite.connMock.readBuffer) //nolint: errcheck
-	rec.Reset()
-
-	rec.Type = record.TypeApplicationData
-	rec.Version = record.Version12
-
-	rec.Payload.Write([]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
-	rec.Dump(&suite.connMock.readBuffer) //nolint: errcheck
-
-	resultBuffer := &bytes.Buffer{}
-	buf := make([]byte, 2)
-
-	for {
-		n, err := suite.c.Read(buf)
-		if errors.Is(err, io.EOF) {
-			break
-		}
-
-		resultBuffer.Write(buf[:n])
-	}
-
-	suite.Equal([]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, resultBuffer.Bytes())
-}
-
-func (suite *ConnTestSuite) TestReadUnexpected() {
-	suite.connMock.On("Read", mock.Anything).Return(0, nil)
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	rec.Type = record.TypeChangeCipherSpec
-	rec.Version = record.Version12
-
-	rec.Payload.WriteByte(0x01)
-	rec.Dump(&suite.connMock.readBuffer) //nolint: errcheck
-	rec.Reset()
-
-	rec.Type = record.TypeHandshake
-	rec.Version = record.Version12
-
-	rec.Payload.Write([]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
-	rec.Dump(&suite.connMock.readBuffer) //nolint: errcheck
-
-	buf := make([]byte, 2)
-
-	for {
-		_, err := suite.c.Read(buf)
-
-		switch {
-		case err == nil:
-		case errors.Is(err, io.EOF):
-			suite.FailNow("unexpected to finish")
-		default:
-			return
-		}
-	}
-}
-
-func (suite *ConnTestSuite) TestWrite() {
-	suite.connMock.On("Write", mock.Anything).Return(0, nil)
-
-	dataToRec := make([]byte, record.TLSMaxRecordSize*2)
-	rand.Read(dataToRec) //nolint: staticcheck, errcheck
-
-	n, err := suite.c.Write(dataToRec)
-	suite.NoError(err)
-	suite.Equal(len(dataToRec), n)
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	buf := &bytes.Buffer{}
-
-	for {
-		if err := rec.Read(&suite.connMock.writeBuffer); err != nil {
-			break
-		}
-
-		suite.Equal(record.TypeApplicationData, rec.Type)
-		suite.Equal(record.Version12, rec.Version)
-		rec.Payload.WriteTo(buf) //nolint: errcheck
-	}
-
-	suite.Equal(dataToRec, buf.Bytes())
-}
-
-func TestConn(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &ConnTestSuite{})
-}

mtglib/internal/faketls/init.go

@@ -1,59 +0,0 @@
-package faketls
-
-import (
-	"bytes"
-	"errors"
-)
-
-const (
-	// RandomLen defines a size of the random digest in TLS Hellos.
-	RandomLen = 32
-
-	// ClientHelloRandomOffset is an offset in ClientHello record where
-	// random digest is started.
-	ClientHelloRandomOffset = 6
-
-	// ClientHelloSessionIDOffset is an offset in ClientHello record where
-	// SessionID is started.
-	ClientHelloSessionIDOffset = ClientHelloRandomOffset + RandomLen
-
-	// ClientHelloMinLen is a minimal possible length of
-	// ClientHello record.
-	ClientHelloMinLen = 6
-
-	// WelcomePacketRandomOffset is an offset of random in ServerHello
-	// packet (including record envelope).
-	WelcomePacketRandomOffset = 11
-
-	// HandshakeTypeClient is a value representing a client handshake.
-	HandshakeTypeClient = 0x01
-
-	// HandshakeTypeServer is a value representing a server handshake.
-	HandshakeTypeServer = 0x02
-
-	// ChangeCipherValue is a value representing a change cipher
-	// specification record.
-	ChangeCipherValue = 0x01
-
-	// ExtensionSNI is a value for TLS extension 'SNI'.
-	ExtensionSNI = 0x00
-)
-
-var (
-	// ErrBadDigest is returned if given TLS Client Hello mismatches with a
-	// derived one.
-	ErrBadDigest = errors.New("bad digest")
-
-	serverHelloSuffix = []byte{
-		0x00,       // no compression
-		0x00, 0x2e, // 46 bytes of data
-		0x00, 0x2b, // Extension - Supported Versions
-		0x00, 0x02, // 2 bytes are following
-		0x03, 0x04, // TLS 1.3
-		0x00, 0x33, // Extension - Key Share
-		0x00, 0x24, // 36 bytes
-		0x00, 0x1d, // x25519 curve
-		0x00, 0x20, // 32 bytes of key
-	}
-	clientHelloEmptyRandom = bytes.Repeat([]byte{0}, RandomLen)
-)

mtglib/internal/faketls/record/init.go

@@ -1,84 +0,0 @@
-package record
-
-import "fmt"
-
-const TLSMaxRecordSize = 65535 // max uint16
-
-type Type uint8
-
-const (
-	// TypeChangeCipherSpec defines a byte value of the TLS record when a
-	// peer wants to change a specifications of the chosen cipher.
-	TypeChangeCipherSpec Type = 0x14
-
-	// TypeHandshake defines a byte value of the TLS record when a peer
-	// initiates a new TLS connection and wants to make a handshake
-	// ceremony.
-	TypeHandshake Type = 0x16
-
-	// TypeApplicationData defines a byte value of the TLS record when a
-	// peer sends an user data, not a control frames.
-	TypeApplicationData Type = 0x17
-)
-
-func (t Type) String() string {
-	switch t {
-	case TypeChangeCipherSpec:
-		return "changeCipher(0x14)"
-	case TypeHandshake:
-		return "handshake(0x16)"
-	case TypeApplicationData:
-		return "applicationData(0x17)"
-	}
-
-	return fmt.Sprintf("unknown(%#x)", byte(t))
-}
-
-func (t Type) Valid() error {
-	switch t {
-	case TypeChangeCipherSpec, TypeHandshake, TypeApplicationData:
-		return nil
-	}
-
-	return fmt.Errorf("unknown type %#x", byte(t))
-}
-
-type Version uint16
-
-const (
-	// Version10 defines a TLS1.0.
-	Version10 Version = 769 // 0x03 0x01
-
-	// Version11 defines a TLS1.1.
-	Version11 Version = 770 // 0x03 0x02
-
-	// Version12 defines a TLS1.2.
-	Version12 Version = 771 // 0x03 0x03
-
-	// Version13 defines a TLS1.3.
-	Version13 Version = 772 // 0x03 0x04
-)
-
-func (v Version) String() string {
-	switch v {
-	case Version10:
-		return "tls1.0"
-	case Version11:
-		return "tls1.1"
-	case Version12:
-		return "tls1.2"
-	case Version13:
-		return "tls1.3"
-	}
-
-	return fmt.Sprintf("tls?(%d)", uint16(v))
-}
-
-func (v Version) Valid() error {
-	switch v {
-	case Version10, Version11, Version12, Version13:
-		return nil
-	}
-
-	return fmt.Errorf("unknown version %d", uint16(v))
-}

mtglib/internal/faketls/record/init_test.go

@@ -1,79 +0,0 @@
-package record_test
-
-import (
-	"testing"
-
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-	"github.com/stretchr/testify/suite"
-)
-
-type TypeTestSuite struct {
-	suite.Suite
-}
-
-func (suite *TypeTestSuite) TestChangeCipherSpec() {
-	suite.Contains(record.TypeChangeCipherSpec.String(), "changeCipher")
-	suite.Contains(record.TypeChangeCipherSpec.String(), "0x14")
-	suite.NoError(record.TypeChangeCipherSpec.Valid())
-}
-
-func (suite *TypeTestSuite) TestHandshake() {
-	suite.Contains(record.TypeHandshake.String(), "handshake")
-	suite.Contains(record.TypeHandshake.String(), "0x16")
-	suite.NoError(record.TypeHandshake.Valid())
-}
-
-func (suite *TypeTestSuite) TestApplicationData() {
-	suite.Contains(record.TypeApplicationData.String(), "applicationData")
-	suite.Contains(record.TypeApplicationData.String(), "0x17")
-	suite.NoError(record.TypeApplicationData.Valid())
-}
-
-func (suite *TypeTestSuite) TestUnknown() {
-	value := record.Type(0x20)
-
-	suite.Contains(value.String(), "unknown")
-	suite.Contains(value.String(), "0x20")
-	suite.Error(value.Valid())
-}
-
-type VersionTestSuite struct {
-	suite.Suite
-}
-
-func (suite *VersionTestSuite) Test10() {
-	suite.Equal("tls1.0", record.Version10.String())
-	suite.NoError(record.Version10.Valid())
-}
-
-func (suite *VersionTestSuite) Test11() {
-	suite.Equal("tls1.1", record.Version11.String())
-	suite.NoError(record.Version11.Valid())
-}
-
-func (suite *VersionTestSuite) Test12() {
-	suite.Equal("tls1.2", record.Version12.String())
-	suite.NoError(record.Version12.Valid())
-}
-
-func (suite *VersionTestSuite) Test13() {
-	suite.Equal("tls1.3", record.Version13.String())
-	suite.NoError(record.Version13.Valid())
-}
-
-func (suite *VersionTestSuite) TestUnknown() {
-	value := record.Version(900)
-
-	suite.Equal("tls?(900)", value.String())
-	suite.Error(value.Valid())
-}
-
-func TestType(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &TypeTestSuite{})
-}
-
-func TestVersion(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &VersionTestSuite{})
-}

mtglib/internal/faketls/record/pools.go

@@ -1,20 +0,0 @@
-package record
-
-import (
-	"sync"
-)
-
-var recordPool = sync.Pool{
-	New: func() any {
-		return &Record{}
-	},
-}
-
-func AcquireRecord() *Record {
-	return recordPool.Get().(*Record) //nolint: forcetypeassert
-}
-
-func ReleaseRecord(r *Record) {
-	r.Reset()
-	recordPool.Put(r)
-}

mtglib/internal/faketls/record/record.go

@@ -1,86 +0,0 @@
-package record
-
-import (
-	"bytes"
-	"encoding/base64"
-	"encoding/binary"
-	"fmt"
-	"io"
-)
-
-type Record struct {
-	Type    Type
-	Version Version
-	Payload bytes.Buffer
-}
-
-func (r *Record) String() string {
-	return fmt.Sprintf("<tlsRecord(type=%v, version=%v, payload=%s)>",
-		r.Type,
-		r.Version,
-		base64.StdEncoding.EncodeToString(r.Payload.Bytes()))
-}
-
-func (r *Record) Reset() {
-	r.Payload.Reset()
-}
-
-func (r *Record) Read(reader io.Reader) error {
-	r.Reset()
-
-	buf := [2]byte{}
-
-	if _, err := io.ReadFull(reader, buf[:1]); err != nil {
-		return fmt.Errorf("cannot read type: %w", err)
-	}
-
-	r.Type = Type(buf[0])
-	if err := r.Type.Valid(); err != nil {
-		return fmt.Errorf("invalid type: %w", err)
-	}
-
-	if _, err := io.ReadFull(reader, buf[:]); err != nil {
-		return fmt.Errorf("cannot read version: %w", err)
-	}
-
-	r.Version = Version(binary.BigEndian.Uint16(buf[:]))
-	if err := r.Version.Valid(); err != nil {
-		return fmt.Errorf("invalid version: %w", err)
-	}
-
-	if _, err := io.ReadFull(reader, buf[:]); err != nil {
-		return fmt.Errorf("cannot read payload length: %w", err)
-	}
-
-	length := int64(binary.BigEndian.Uint16(buf[:]))
-	if _, err := io.CopyN(&r.Payload, reader, length); err != nil {
-		return fmt.Errorf("cannot read payload: %w", err)
-	}
-
-	return nil
-}
-
-func (r *Record) Dump(writer io.Writer) error {
-	buf := [2]byte{byte(r.Type), 0}
-	if _, err := writer.Write(buf[:1]); err != nil {
-		return fmt.Errorf("cannot dump record type: %w", err)
-	}
-
-	binary.BigEndian.PutUint16(buf[:], uint16(r.Version))
-
-	if _, err := writer.Write(buf[:]); err != nil {
-		return fmt.Errorf("cannot dump version: %w", err)
-	}
-
-	binary.BigEndian.PutUint16(buf[:], uint16(r.Payload.Len()))
-
-	if _, err := writer.Write(buf[:]); err != nil {
-		return fmt.Errorf("cannot dump payload length: %w", err)
-	}
-
-	if _, err := writer.Write(r.Payload.Bytes()); err != nil {
-		return fmt.Errorf("cannot dump record: %w", err)
-	}
-
-	return nil
-}

mtglib/internal/faketls/record/record_test.go

@@ -1,110 +0,0 @@
-package record_test
-
-import (
-	"bytes"
-	"encoding/base64"
-	"encoding/json"
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/suite"
-)
-
-type RecordTestSnapshot struct {
-	Type    int    `json:"type"`
-	Version int    `json:"version"`
-	Payload string `json:"payload"`
-	Record  string `json:"record"`
-}
-
-func (r RecordTestSnapshot) RecordBytes() []byte {
-	data, _ := base64.StdEncoding.DecodeString(r.Record)
-
-	return data
-}
-
-func (r RecordTestSnapshot) PayloadBytes() []byte {
-	data, _ := base64.StdEncoding.DecodeString(r.Payload)
-
-	return data
-}
-
-type RecordTestSuite struct {
-	suite.Suite
-
-	r   *record.Record
-	buf *bytes.Buffer
-}
-
-func (suite *RecordTestSuite) SetupTest() {
-	suite.r = record.AcquireRecord()
-	suite.buf = &bytes.Buffer{}
-}
-
-func (suite *RecordTestSuite) TearDownTest() {
-	record.ReleaseRecord(suite.r)
-	suite.buf.Reset()
-}
-
-func (suite *RecordTestSuite) TestIdempotent() {
-	suite.r.Type = record.TypeApplicationData
-	suite.r.Version = record.Version13
-
-	suite.r.Payload.Write([]byte{1, 2, 3})
-	suite.NoError(suite.r.Dump(suite.buf))
-
-	suite.r.Reset()
-	suite.NoError(suite.r.Read(suite.buf))
-
-	suite.Equal(0, suite.buf.Len())
-	suite.Equal(record.TypeApplicationData, suite.r.Type)
-	suite.Equal(record.Version13, suite.r.Version)
-	suite.Equal([]byte{1, 2, 3}, suite.r.Payload.Bytes())
-}
-
-func (suite *RecordTestSuite) TestString() {
-	_ = suite.r.String()
-}
-
-func (suite *RecordTestSuite) TestSnapshot() {
-	files, err := os.ReadDir("testdata")
-	suite.NoError(err)
-
-	testData := map[string]string{}
-
-	for _, f := range files {
-		testData[f.Name()] = filepath.Join("testdata", f.Name())
-	}
-
-	for name, pathV := range testData {
-		path := pathV
-
-		suite.T().Run(name, func(t *testing.T) {
-			data, err := os.ReadFile(path)
-			assert.NoError(t, err)
-
-			snapshot := &RecordTestSnapshot{}
-			assert.NoError(t, json.Unmarshal(data, snapshot))
-
-			rec := record.AcquireRecord()
-			defer record.ReleaseRecord(rec)
-
-			assert.NoError(t, rec.Read(bytes.NewReader(snapshot.RecordBytes())))
-			assert.Equal(t, snapshot.Type, int(rec.Type))
-			assert.Equal(t, snapshot.Version, int(rec.Version))
-			assert.Equal(t, snapshot.PayloadBytes(), rec.Payload.Bytes())
-
-			buf := &bytes.Buffer{}
-			assert.NoError(t, rec.Dump(buf))
-			assert.Equal(t, snapshot.RecordBytes(), buf.Bytes())
-		})
-	}
-}
-
-func TestRecord(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &RecordTestSuite{})
-}

mtglib/internal/faketls/record/testdata/05eb6b71f87b6802.json

@@ -1,6 +0,0 @@
-{
-  "type": 20,
-  "version": 772,
-  "payload": "sxS+0oAyk+NBv0LLVtQOp9WSx4CweyUZPz01tQ0o4oyp8aaBl6/kMFvLq3q52KE8lCiKejLw2NxVBUkE+4izCf2gLx9qfr81opWnqJTChWzcDijvttbq9cmtDFNL+odKsS3v1/TfYEFtPsoRPrJRmOHRAnqnf49Y5Q==",
-  "record": "FAMEAHmzFL7SgDKT40G/QstW1A6n1ZLHgLB7JRk/PTW1DSjijKnxpoGXr+QwW8urernYoTyUKIp6MvDY3FUFSQT7iLMJ/aAvH2p+vzWilaeolMKFbNwOKO+21ur1ya0MU0v6h0qxLe/X9N9gQW0+yhE+slGY4dECeqd/j1jl"
-}

mtglib/internal/faketls/record/testdata/4eef4abc15b206b6.json

@@ -1,6 +0,0 @@
-{
-  "type": 22,
-  "version": 772,
-  "payload": "waNH223htyxCBKAb6hm0u/SK/9mhI8Ck91nfWob7QMOaIREogrDYREJH4Djcp47XrpAlEaUIDiCvoFLVJ/LK1nYs4swzfHSSl/+Aj1eqPA63XqPa8EG4FAbf0DwjwXxV9qVIhvP9b2TafKbzr4Yb5GCygzFRb/zawA==",
-  "record": "FgMEAHnBo0fbbeG3LEIEoBvqGbS79Ir/2aEjwKT3Wd9ahvtAw5ohESiCsNhEQkfgONynjteukCURpQgOIK+gUtUn8srWdizizDN8dJKX/4CPV6o8Drdeo9rwQbgUBt/QPCPBfFX2pUiG8/1vZNp8pvOvhhvkYLKDMVFv/NrA"
-}

mtglib/internal/faketls/record/testdata/736f358216afe91f.json

@@ -1,6 +0,0 @@
-{
-  "type": 23,
-  "version": 769,
-  "payload": "jmJ0o1E5+ehAHHYAbCo4AMV03X7RSivYl250s06nD9CO44fyjaoGELz0N7IeCg1jFKcRVSCRmYYmiIY9wydn2fXOJhKif8B0BlM3qhbethYgyP+l1S8hyyETpIiOtiiiOnAJwl1D1j9OryFiJFSdRRXReIMZ4CPqPg==",
-  "record": "FwMBAHmOYnSjUTn56EAcdgBsKjgAxXTdftFKK9iXbnSzTqcP0I7jh/KNqgYQvPQ3sh4KDWMUpxFVIJGZhiaIhj3DJ2fZ9c4mEqJ/wHQGUzeqFt62FiDI/6XVLyHLIROkiI62KKI6cAnCXUPWP06vIWIkVJ1FFdF4gxngI+o+"
-}

mtglib/internal/faketls/record/testdata/8405d94222bd0b6a.json

@@ -1,6 +0,0 @@
-{
-  "type": 22,
-  "version": 769,
-  "payload": "hBnpBnNUdlqe/rKXa7Judcz79u7AkUgSGOycn8EqvbkZpVxnI31rNOvAsPZqG+GF7DWJ3R7H2ETmFmrpnyyng32MjSs1jptmV1oAs63zTADD7sVipgid9AJHwfl4CrC3FIQr43IPMYd29JPOl5bqu/SfrgI16PBiJw==",
-  "record": "FgMBAHmEGekGc1R2Wp7+spdrsm51zPv27sCRSBIY7JyfwSq9uRmlXGcjfWs068Cw9mob4YXsNYndHsfYROYWaumfLKeDfYyNKzWOm2ZXWgCzrfNMAMPuxWKmCJ30AkfB+XgKsLcUhCvjcg8xh3b0k86Xluq79J+uAjXo8GIn"
-}

mtglib/internal/faketls/record/testdata/9036f76e517f0cd1.json

@@ -1,6 +0,0 @@
-{
-  "type": 23,
-  "version": 770,
-  "payload": "Vm/C+DO56czlbtR915aHzsugSyDtp8CtojF9w1jKY0efyyfcLrNuhNg/pZm3gQ7v2BBbL1UJ97v/RIjST+5gRIfg3bBN1BE9hkf+N2AYY2lHLi0yeInHB0zFWPeHscsDopDFadIi5KtC8HvbEMuK+kK8POVk5tN9UQ==",
-  "record": "FwMCAHlWb8L4M7npzOVu1H3XlofOy6BLIO2nwK2iMX3DWMpjR5/LJ9wus26E2D+lmbeBDu/YEFsvVQn3u/9EiNJP7mBEh+DdsE3UET2GR/43YBhjaUcuLTJ4iccHTMVY94exywOikMVp0iLkq0Lwe9sQy4r6Qrw85WTm031R"
-}

mtglib/internal/faketls/record/testdata/9244766a0fe4a02a.json

@@ -1,6 +0,0 @@
-{
-  "type": 22,
-  "version": 770,
-  "payload": "ajPzpsgk4gwm2stRQKbllvKRLdI7vmyaj1uxEJ/kKoQnQSPumdDNKD618U2Cq6PVd0/b+9YtH67Uzx1QxtpKuby5fUXqw06WUuDAQsmjq7F26EkE5FND6rQUjUPC+e1U0dF4TQzOUSS4IAkFQPAaVehUVTRxVWa/0g==",
-  "record": "FgMCAHlqM/OmyCTiDCbay1FApuWW8pEt0ju+bJqPW7EQn+QqhCdBI+6Z0M0oPrXxTYKro9V3T9v71i0frtTPHVDG2kq5vLl9RerDTpZS4MBCyaOrsXboSQTkU0PqtBSNQ8L57VTR0XhNDM5RJLggCQVA8BpV6FRVNHFVZr/S"
-}

mtglib/internal/faketls/record/testdata/9255c73d3de76e7b.json

@@ -1,6 +0,0 @@
-{
-  "type": 20,
-  "version": 771,
-  "payload": "d1Hiv1NYVgEDR9mtJyv9j8mg3dWqfUpeKfOsL+jzSDfVIxeDiJZFLDT50TjNW44/yEOVEX/Y/pk+wnc7E8aCEiwGwAvB+Insw1UCJ2ejt689VWLo2u4klGVKTHuOpUvdGVTc7Lo4FAt91KQSPLYB5iqxomjEv5e3Vg==",
-  "record": "FAMDAHl3UeK/U1hWAQNH2a0nK/2PyaDd1ap9Sl4p86wv6PNIN9UjF4OIlkUsNPnROM1bjj/IQ5URf9j+mT7CdzsTxoISLAbAC8H4iezDVQInZ6O3rz1VYuja7iSUZUpMe46lS90ZVNzsujgUC33UpBI8tgHmKrGiaMS/l7dW"
-}

mtglib/internal/faketls/record/testdata/aeb65b9924315cf8.json

@@ -1,6 +0,0 @@
-{
-  "type": 23,
-  "version": 771,
-  "payload": "wbdU1CbrzuAJDsh6CFjGyE+AFArJj/Wmsa2wtDyW0kRuE2vUO8gg+nXkg0kkoz0WnvQEOdaswfJIaVrloD78yoyeQVfBB+VUP/63vqn60v5ccaQEn0jLdxgLjiTAxKDQDxCTMRoLnFE2ZZf28zw+HfqpIxiOZs8LhQ==",
-  "record": "FwMDAHnBt1TUJuvO4AkOyHoIWMbIT4AUCsmP9aaxrbC0PJbSRG4Ta9Q7yCD6deSDSSSjPRae9AQ51qzB8khpWuWgPvzKjJ5BV8EH5VQ//re+qfrS/lxxpASfSMt3GAuOJMDEoNAPEJMxGgucUTZll/bzPD4d+qkjGI5mzwuF"
-}

mtglib/internal/faketls/record/testdata/b0acd44296056b54.json

@@ -1,6 +0,0 @@
-{
-  "type": 23,
-  "version": 772,
-  "payload": "qqnBMb1Af3zZt4DPHpVRuIiON9ODGJUNFicFjranORh67L/HI4D6HnHyycZFUSBOw2FjMBF6UialY8snOYaRKrQmQzuUNg1Ztq7yAZ+Lgj3TBarR6OMlYhEAY0Px9Xv1UuJ0YcvQx33gdM1skJ5HBR3yZvEKNJV1LA==",
-  "record": "FwMEAHmqqcExvUB/fNm3gM8elVG4iI4304MYlQ0WJwWOtqc5GHrsv8cjgPoecfLJxkVRIE7DYWMwEXpSJqVjyyc5hpEqtCZDO5Q2DVm2rvIBn4uCPdMFqtHo4yViEQBjQ/H1e/VS4nRhy9DHfeB0zWyQnkcFHfJm8Qo0lXUs"
-}

mtglib/internal/faketls/record/testdata/c0545a13fd9a3fa3.json

@@ -1,6 +0,0 @@
-{
-  "type": 20,
-  "version": 769,
-  "payload": "NEe735TuQFp7bWpFQhASas/e1XaySvus0ovXmkfCbFq334MyFHq2eDMadziXsfu/GfBjoYggvk0LgYUeoAkBNKR0dfSovjSndaqmIUonoWl+6sZObiGZkRIMwuY2q4Eaw4/iuDu/pZhjRW/iAIH+YH7cyk/1tgdJDg==",
-  "record": "FAMBAHk0R7vflO5AWnttakVCEBJqz97VdrJK+6zSi9eaR8JsWrffgzIUerZ4Mxp3OJex+78Z8GOhiCC+TQuBhR6gCQE0pHR19Ki+NKd1qqYhSiehaX7qxk5uIZmREgzC5jargRrDj+K4O7+lmGNFb+IAgf5gftzKT/W2B0kO"
-}

mtglib/internal/faketls/record/testdata/f083f4501668b759.json

@@ -1,6 +0,0 @@
-{
-  "type": 22,
-  "version": 771,
-  "payload": "wrXjZrPm3OSyzO0klv6/G+z2PDloR/colS/RlWwQE31Vb2xm8YkEchDDKwlc/KPLD73qMoz3MQOQLtSLc8LhVYp+l7L9jz49yTaVKtBI5UuGbo09snsKxFCgCyYUBETKabATBQtiaEu/D8dmF4Yk/2ww4sEb8DwKLQ==",
-  "record": "FgMDAHnCteNms+bc5LLM7SSW/r8b7PY8OWhH9yiVL9GVbBATfVVvbGbxiQRyEMMrCVz8o8sPveoyjPcxA5Au1ItzwuFVin6Xsv2PPj3JNpUq0EjlS4ZujT2yewrEUKALJhQERMppsBMFC2JoS78Px2YXhiT/bDDiwRvwPAot"
-}

mtglib/internal/faketls/record/testdata/f5696bcdffd11706.json

@@ -1,6 +0,0 @@
-{
-  "type": 20,
-  "version": 770,
-  "payload": "OU5s8Sa11hpXWEarWzFlX55IZt3Eo+F4AMbQ/2RwB4rfHS/JNl8n63OR4oYs9QXw3RfCrYJuU9n6Xn+I/+7ZzAgZ0PbLSXW1PrLtttdfmhTErK90b49YEWdY9na4g++NMkKykwgXvY1hNxZIHX/qawEWJgxXUR3DdQ==",
-  "record": "FAMCAHk5TmzxJrXWGldYRqtbMWVfnkhm3cSj4XgAxtD/ZHAHit8dL8k2Xyfrc5Hihiz1BfDdF8Ktgm5T2fpef4j/7tnMCBnQ9stJdbU+su2211+aFMSsr3Rvj1gRZ1j2driD740yQrKTCBe9jWE3Fkgdf+prARYmDFdRHcN1"
-}

mtglib/internal/faketls/testdata/client-hello-bad-fa2e46cdb33e2a1b.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181365,
-  "random": "XvCPc3aAbHbhRLv0kUmy6BfPZOGvsused5/HNsKXEPs=",
-  "sessionId": "St2BZ2uHMFn3B2trD1jfdtpjoJOOg6JBeLhFcyCMCq4=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/testdata/client-hello-ok-19dfe38384b9884b.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181365,
-  "random": "XvCPc3aAbHbhRLv0kUmy6BfPZOGvsused5/HNsKXEPs=",
-  "sessionId": "St2BZ2uHMFn3B2trD1jfdtpjoJOOg6JBeLhFcyCMCq4=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/testdata/client-hello-ok-48f8a72a56f3174a.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181352,
-  "random": "oYEu33jl+zQbUKMtQbV1OHB0gXIM2y2aq9iY0QX12os=",
-  "sessionId": "FGqA3ZFYrSlj//xl7lammNn64K9/MK2mQ3HJUGvP+8g=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/testdata/client-hello-ok-651054256093c6cd.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181352,
-  "random": "5V5sSprk/tFIgy+x1BeKNGhLlFkqfggLpgN7GYOA1ro=",
-  "sessionId": "jxr4d6PXPDk+Lwx3WUp9wvj8TGlOxEdrRJ0ydyJ9+H8=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/testdata/client-hello-ok-79d01ef18a9d2621.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181365,
-  "random": "8xljlOhkDlkafEF5vu3e1r3fWvh8AX548wC3hLZ3szQ=",
-  "sessionId": "00uvDYKnFyZFKyf3HlLwWGCOyeHsPFiU5UZ+Fs5pDAU=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/testdata/client-hello-ok-7a5569f05b118145.json

@@ -1,8 +0,0 @@
-{
-  "time": 1617181352,
-  "random": "zja3MLZ8WGSfsQRtPV75+tY6gbK3zKPi1Sy7SBBafg4=",
-  "sessionId": "qPut2yMqXa9zGLII/872SQ3d4Tfqo0uoDb7tpkRfBnA=",
-  "host": "storage.googleapis.com",
-  "cipherSuite": 4867,
-  "full": "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"
-}

mtglib/internal/faketls/welcome.go

@@ -1,91 +0,0 @@
-package faketls
-
-import (
-	"bytes"
-	"crypto/hmac"
-	"crypto/rand"
-	"crypto/sha256"
-	"encoding/binary"
-	"io"
-	mrand "math/rand/v2"
-
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-	"golang.org/x/crypto/curve25519"
-)
-
-func SendWelcomePacket(writer io.Writer, secret []byte, clientHello ClientHello) error {
-	buf := &bytes.Buffer{}
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	rec.Type = record.TypeHandshake
-	rec.Version = record.Version12
-
-	generateServerHello(&rec.Payload, clientHello)
-	rec.Dump(buf) //nolint: errcheck
-	rec.Reset()
-
-	rec.Type = record.TypeChangeCipherSpec
-	rec.Version = record.Version12
-	rec.Payload.WriteByte(ChangeCipherValue)
-
-	rec.Dump(buf) //nolint: errcheck
-	rec.Reset()
-
-	rec.Type = record.TypeApplicationData
-	rec.Version = record.Version12
-
-	if _, err := io.CopyN(&rec.Payload, rand.Reader, int64(1024+mrand.IntN(3092))); err != nil {
-		panic(err)
-	}
-
-	rec.Dump(buf) //nolint: errcheck
-
-	packet := buf.Bytes()
-	mac := hmac.New(sha256.New, secret)
-
-	mac.Write(clientHello.Random[:])
-	mac.Write(packet)
-
-	copy(packet[WelcomePacketRandomOffset:], mac.Sum(nil))
-
-	if _, err := writer.Write(packet); err != nil {
-		return err //nolint: wrapcheck
-	}
-
-	return nil
-}
-
-func generateServerHello(writer io.Writer, clientHello ClientHello) {
-	bodyBuf := &bytes.Buffer{}
-
-	sliceBuf := [2]byte{}
-	digest := [RandomLen]byte{}
-
-	binary.BigEndian.PutUint16(sliceBuf[:], uint16(record.Version12))
-	bodyBuf.Write(sliceBuf[:])
-	bodyBuf.Write(digest[:])
-	bodyBuf.WriteByte(byte(len(clientHello.SessionID)))
-	bodyBuf.Write(clientHello.SessionID)
-
-	binary.BigEndian.PutUint16(sliceBuf[:], clientHello.CipherSuite)
-	bodyBuf.Write(sliceBuf[:])
-	bodyBuf.Write(serverHelloSuffix)
-
-	scalar := [32]byte{}
-
-	if _, err := rand.Read(scalar[:]); err != nil {
-		panic(err)
-	}
-
-	curve, _ := curve25519.X25519(scalar[:], curve25519.Basepoint)
-	bodyBuf.Write(curve)
-
-	header := [4]byte{0, 0, 0, 0}
-	binary.BigEndian.PutUint32(header[:], uint32(bodyBuf.Len()))
-	header[0] = HandshakeTypeServer
-
-	writer.Write(header[:]) //nolint: errcheck
-	bodyBuf.WriteTo(writer) //nolint: errcheck
-}

mtglib/internal/faketls/welcome_test.go

@@ -1,82 +0,0 @@
-package faketls_test
-
-import (
-	"bytes"
-	"crypto/hmac"
-	"crypto/rand"
-	"crypto/sha256"
-	"testing"
-	"time"
-
-	"github.com/9seconds/mtg/v2/mtglib"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
-	"github.com/stretchr/testify/suite"
-)
-
-type WelcomeTestSuite struct {
-	suite.Suite
-
-	h      *faketls.ClientHello
-	buf    *bytes.Buffer
-	secret mtglib.Secret
-}
-
-func (suite *WelcomeTestSuite) SetupTest() {
-	suite.h = &faketls.ClientHello{
-		Time:        time.Now(),
-		Host:        "google.com",
-		CipherSuite: 4867,
-		SessionID:   make([]byte, 32),
-	}
-
-	_, err := rand.Read(suite.h.SessionID) //nolint: staticcheck
-	suite.NoError(err)
-
-	_, err = rand.Read(suite.h.Random[:]) //nolint: staticcheck
-	suite.NoError(err)
-
-	suite.buf = &bytes.Buffer{}
-
-	suite.secret = mtglib.GenerateSecret("google.com")
-}
-
-func (suite *WelcomeTestSuite) TestOk() {
-	suite.NoError(faketls.SendWelcomePacket(suite.buf, suite.secret.Key[:], *suite.h))
-
-	welcomePacket := []byte{}
-	welcomePacket = append(welcomePacket, suite.buf.Bytes()...)
-
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
-	suite.NoError(rec.Read(suite.buf))
-	suite.Equal(record.TypeHandshake, rec.Type)
-	suite.Equal(record.Version12, rec.Version)
-
-	suite.NoError(rec.Read(suite.buf))
-	suite.Equal(record.TypeChangeCipherSpec, rec.Type)
-	suite.Equal(record.Version12, rec.Version)
-
-	suite.NoError(rec.Read(suite.buf))
-	suite.Equal(record.TypeApplicationData, rec.Type)
-	suite.Equal(record.Version12, rec.Version)
-	suite.Empty(suite.buf.Bytes())
-
-	random := make([]byte, 32)
-	copy(random, welcomePacket[11:])
-
-	empty := make([]byte, 32)
-	copy(welcomePacket[11:], empty)
-
-	mac := hmac.New(sha256.New, suite.secret.Key[:])
-	mac.Write(suite.h.Random[:])
-	mac.Write(welcomePacket)
-
-	suite.Equal(random, mac.Sum(nil))
-}
-
-func TestWelcome(t *testing.T) {
-	t.Parallel()
-	suite.Run(t, &WelcomeTestSuite{})
-}

mtglib/internal/relay/init.go

@@ -1,9 +1,5 @@
 package relay
 
-const (
-	copyBufferSize = 64 * 1024
-)
-
 type Logger interface {
 	Printf(msg string, args ...any)
 }

mtglib/internal/relay/relay.go

@@ -6,6 +6,7 @@ import (
 	"io"
 
 	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
 )
 
 func Relay(ctx context.Context, log Logger, telegramConn, clientConn essentials.Conn) {
@@ -35,7 +36,7 @@ func Relay(ctx context.Context, log Logger, telegramConn, clientConn essentials.
 }
 
 func pump(log Logger, src, dst essentials.Conn, direction string) {
-	var buf [copyBufferSize]byte
+	var buf [tls.MaxRecordPayloadSize]byte
 
 	defer src.CloseRead()  //nolint: errcheck
 	defer dst.CloseWrite() //nolint: errcheck

mtglib/internal/tls/conn.go

@@ -0,0 +1,86 @@
+package tls
+
+import (
+	"bufio"
+	"bytes"
+
+	"github.com/9seconds/mtg/v2/essentials"
+)
+
+const (
+	SizeRecordType = 1
+	SizeVersion    = 2
+	SizeSize       = 2
+	SizeHeader     = SizeRecordType + SizeVersion + SizeSize
+
+	MaxRecordSize        = 16384
+	MaxRecordPayloadSize = MaxRecordSize - SizeHeader
+	DefaultBufferSize    = 4096
+
+	TypeChangeCipherSpec = 0x14
+	TypeHandshake        = 0x16
+	TypeApplicationData  = 0x17
+)
+
+// TLS 1.2 is used for both TLS 1.2 and 1.3
+var TLSVersion = [SizeVersion]byte{3, 3}
+
+// Conn presents an established TLS 1.3 connection, after handshake
+type Conn struct {
+	essentials.Conn
+
+	p *connPayload
+}
+
+type connPayload struct {
+	readBuf      bytes.Buffer
+	writeBuf     bytes.Buffer
+	connBuffered *bufio.Reader
+	read         bool
+	write        bool
+}
+
+func (c Conn) Write(p []byte) (int, error) {
+	if !c.p.write {
+		return c.Conn.Write(p)
+	}
+
+	return len(p), WriteRecord(c.Conn, p)
+}
+
+func (c Conn) Read(p []byte) (int, error) {
+	if !c.p.read {
+		return c.Conn.Read(p)
+	}
+
+	for {
+		if n, err := c.p.readBuf.Read(p); err == nil {
+			return n, nil
+		}
+
+		recordType, _, err := ReadRecord(c.p.connBuffered, &c.p.readBuf)
+		if err != nil {
+			return 0, err
+		}
+
+		if recordType != TypeApplicationData {
+			c.p.readBuf.Reset()
+		}
+	}
+}
+
+func New(conn essentials.Conn, read, write bool) Conn {
+	newConn := Conn{
+		Conn: conn,
+		p: &connPayload{
+			connBuffered: bufio.NewReaderSize(conn, DefaultBufferSize),
+			read:         read,
+			write:        write,
+		},
+	}
+
+	newConn.p.readBuf.Grow(DefaultBufferSize)
+	newConn.p.writeBuf.Grow(DefaultBufferSize)
+
+	return newConn
+}

mtglib/internal/tls/conn_test.go

@@ -0,0 +1,160 @@
+package tls
+
+import (
+	"io"
+	"testing"
+
+	"github.com/9seconds/mtg/v2/internal/testlib"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type ConnTestSuite struct {
+	suite.Suite
+
+	connMock *testlib.EssentialsConnMock
+}
+
+func (suite *ConnTestSuite) SetupTest() {
+	suite.connMock = &testlib.EssentialsConnMock{}
+}
+
+func (suite *ConnTestSuite) TearDownTest() {
+	suite.connMock.AssertExpectations(suite.T())
+}
+
+func (suite *ConnTestSuite) feedRead(raw []byte) {
+	suite.connMock.
+		On("Read", mock.AnythingOfType("[]uint8")).
+		Run(func(args mock.Arguments) {
+			copy(args.Get(0).([]byte), raw)
+		}).
+		Return(len(raw), nil).
+		Once()
+	suite.connMock.
+		On("Read", mock.AnythingOfType("[]uint8")).
+		Return(0, io.EOF).
+		Maybe()
+}
+
+func (suite *ConnTestSuite) TestReadTLSEnabled() {
+	payload := []byte("hello world")
+	suite.feedRead(MakeTLSRecord(0x17, payload))
+
+	conn := New(suite.connMock, true, false)
+
+	buf := make([]byte, 128)
+	n, err := conn.Read(buf)
+
+	suite.NoError(err)
+	suite.Equal(payload, buf[:n])
+}
+
+func (suite *ConnTestSuite) TestReadTLSSkipsNonApplicationData() {
+	raw := append(
+		MakeTLSRecord(0x14, []byte{1}),
+		MakeTLSRecord(0x17, []byte("real data"))...,
+	)
+	suite.feedRead(raw)
+
+	conn := New(suite.connMock, true, false)
+
+	buf := make([]byte, 128)
+	n, err := conn.Read(buf)
+
+	suite.NoError(err)
+	suite.Equal([]byte("real data"), buf[:n])
+}
+
+func (suite *ConnTestSuite) TestReadTLSMultipleRecords() {
+	raw := append(
+		MakeTLSRecord(0x17, []byte("first")),
+		MakeTLSRecord(0x17, []byte("second"))...,
+	)
+	suite.feedRead(raw)
+
+	conn := New(suite.connMock, true, false)
+	buf := make([]byte, 128)
+
+	n, err := conn.Read(buf)
+	suite.NoError(err)
+	suite.Equal([]byte("first"), buf[:n])
+
+	n, err = conn.Read(buf)
+	suite.NoError(err)
+	suite.Equal([]byte("second"), buf[:n])
+}
+
+func (suite *ConnTestSuite) TestReadTLSSmallBuffer() {
+	payload := []byte("hello world, this is a longer payload")
+	suite.feedRead(MakeTLSRecord(0x17, payload))
+
+	conn := New(suite.connMock, true, false)
+
+	small := make([]byte, 5)
+	n, err := conn.Read(small)
+	suite.NoError(err)
+	suite.Equal(payload[:5], small[:n])
+
+	rest := make([]byte, 128)
+	n, err = conn.Read(rest)
+	suite.NoError(err)
+	suite.Equal(payload[5:], rest[:n])
+}
+
+func (suite *ConnTestSuite) TestReadPassthrough() {
+	data := []byte("raw bytes")
+
+	suite.connMock.
+		On("Read", mock.AnythingOfType("[]uint8")).
+		Run(func(args mock.Arguments) {
+			copy(args.Get(0).([]byte), data)
+		}).
+		Return(len(data), nil).
+		Once()
+
+	conn := New(suite.connMock, false, false)
+
+	buf := make([]byte, 128)
+	n, err := conn.Read(buf)
+
+	suite.NoError(err)
+	suite.Equal(data, buf[:n])
+}
+
+func (suite *ConnTestSuite) TestWritePassthrough() {
+	data := []byte("outgoing data")
+
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(len(data), nil).
+		Once()
+
+	conn := New(suite.connMock, false, false)
+
+	n, err := conn.Write(data)
+
+	suite.NoError(err)
+	suite.Equal(len(data), n)
+}
+
+func (suite *ConnTestSuite) TestWriteTLSEnabled() {
+	data := []byte("outgoing data")
+
+	suite.connMock.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Return(len(data), nil).
+		Once()
+
+	conn := New(suite.connMock, false, true)
+
+	n, err := conn.Write(data)
+
+	suite.NoError(err)
+	suite.Equal(len(data), n)
+}
+
+func TestConn(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ConnTestSuite{})
+}

mtglib/internal/tls/fake/bytes_pool.go

@@ -0,0 +1,21 @@
+package fake
+
+import (
+	"bytes"
+	"sync"
+)
+
+var bytesPool = sync.Pool{
+	New: func() any {
+		return &bytes.Buffer{}
+	},
+}
+
+func acquireBuffer() *bytes.Buffer {
+	return bytesPool.Get().(*bytes.Buffer)
+}
+
+func releaseBuffer(b *bytes.Buffer) {
+	b.Reset()
+	bytesPool.Put(b)
+}

mtglib/internal/tls/fake/client_side.go

@@ -0,0 +1,309 @@
+package fake
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+	"slices"
+	"time"
+
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+)
+
+const (
+	TypeHandshakeClient = 0x01
+
+	RandomLen = 32
+	// record_type(1) + version(2) + size(2) + handshake_type(1) + uint24_length(3) + client_version(2)
+	RandomOffset = 1 + 2 + 2 + 1 + 3 + 2
+
+	sniDNSNamesListType = 0
+)
+
+var (
+	emptyRandom = [RandomLen]byte{}
+	extTypeSNI  = [2]byte{}
+)
+
+type ClientHello struct {
+	Random      [RandomLen]byte
+	SessionID   []byte
+	CipherSuite uint16
+}
+
+func ReadClientHello(
+	conn net.Conn,
+	secret []byte,
+	hostname string,
+	tolerateTimeSkewness time.Duration,
+) (*ClientHello, error) {
+	if err := conn.SetReadDeadline(time.Now().Add(ClientHelloReadTimeout)); err != nil {
+		return nil, fmt.Errorf("cannot set read deadline: %w", err)
+	}
+	defer conn.SetReadDeadline(resetDeadline) //nolint: errcheck
+
+	// This is how FakeTLS is organized:
+	//  1. We create sha256 HMAC with a given secret
+	//  2. We dump there a whole TLS frame except of the fact that random
+	//     is filled with all zeroes
+	//  3. Digest is computed. This digest should be XORed with
+	//     original client random
+	//  4. New digest should be all 0 except of last 4 bytes
+	//  5. Last 4 bytes are little endian uint32 of UNIX timestamp when
+	//     this message was created.
+	handshakeCopyBuf := &bytes.Buffer{}
+	reader := io.TeeReader(conn, handshakeCopyBuf)
+
+	reader, err := parseTLSHeader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse tls header: %w", err)
+	}
+
+	reader, err = parseHandshakeHeader(reader)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse handshake header: %w", err)
+	}
+
+	hello, err := parseHandshake(reader)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse handshake: %w", err)
+	}
+
+	sniHostnames, err := parseSNI(reader)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse SNI: %w", err)
+	}
+
+	if !slices.Contains(sniHostnames, hostname) {
+		return nil, fmt.Errorf("cannot find %s in %v", hostname, sniHostnames)
+	}
+
+	digest := hmac.New(sha256.New, secret)
+	// we write a copy of the handshake with client random all nullified.
+	digest.Write(handshakeCopyBuf.Next(RandomOffset))
+	handshakeCopyBuf.Next(RandomLen)
+	digest.Write(emptyRandom[:])
+	digest.Write(handshakeCopyBuf.Bytes())
+
+	computed := digest.Sum(nil)
+
+	for i := range RandomLen {
+		computed[i] ^= hello.Random[i]
+	}
+
+	if subtle.ConstantTimeCompare(emptyRandom[:RandomLen-4], computed[:RandomLen-4]) != 1 {
+		return nil, ErrBadDigest
+	}
+
+	timestamp := int64(binary.LittleEndian.Uint32(computed[RandomLen-4:]))
+	createdAt := time.Unix(timestamp, 0)
+
+	if tdiff := time.Since(createdAt).Abs(); tdiff > tolerateTimeSkewness {
+		return nil, fmt.Errorf("timestamp %q is too old %s", createdAt, tdiff)
+	}
+
+	return hello, nil
+}
+
+func parseTLSHeader(r io.Reader) (io.Reader, error) {
+	// record_type(1) + version(2) + size(2)
+	//   16 - type is 0x16 (handshake record)
+	//   03 01 - protocol version is "3,1" (also known as TLS 1.0)
+	//   00 f8 - 0xF8 (248) bytes of handshake message follows
+	header := [1 + 2 + 2]byte{}
+
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read record header: %w", err)
+	}
+
+	if header[0] != tls.TypeHandshake {
+		return nil, fmt.Errorf("unexpected record type %#x", header[0])
+	}
+
+	if header[1] != 3 || header[2] != 1 {
+		return nil, fmt.Errorf("unexpected protocol version %#x %#x", header[1], header[2])
+	}
+
+	length := int64(binary.BigEndian.Uint16(header[3:]))
+	buf := &bytes.Buffer{}
+
+	_, err := io.CopyN(buf, r, length)
+
+	return buf, err
+}
+
+func parseHandshakeHeader(r io.Reader) (io.Reader, error) {
+	// type(1) + size(3 / uint24)
+	// 01 - handshake message type 0x01 (client hello)
+	// 00 00 f4 - 0xF4 (244) bytes of client hello data follows
+	header := [1 + 3]byte{}
+
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read handshake header: %w", err)
+	}
+
+	if header[0] != TypeHandshakeClient {
+		return nil, fmt.Errorf("incorrect handshake type: %#x", header[0])
+	}
+
+	// unfortunately there is not uint24 in golang, so we just reust header
+	header[0] = 0
+
+	length := int64(binary.BigEndian.Uint32(header[:]))
+	buf := &bytes.Buffer{}
+
+	_, err := io.CopyN(buf, r, length)
+
+	return buf, err
+}
+
+func parseHandshake(r io.Reader) (*ClientHello, error) {
+	//  A protocol version of "3,3" (meaning TLS 1.2) is given.
+	header := [2]byte{}
+
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read client version: %w", err)
+	}
+
+	hello := &ClientHello{}
+
+	if _, err := io.ReadFull(r, hello.Random[:]); err != nil {
+		return nil, fmt.Errorf("cannot read client random: %w", err)
+	}
+
+	if _, err := io.ReadFull(r, header[:1]); err != nil {
+		return nil, fmt.Errorf("cannot read session ID length: %w", err)
+	}
+
+	hello.SessionID = make([]byte, int(header[0]))
+
+	if _, err := io.ReadFull(r, hello.SessionID); err != nil {
+		return nil, fmt.Errorf("cannot read session id: %w", err)
+	}
+
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read cipher suite length: %w", err)
+	}
+
+	cipherSuiteLen := int64(binary.BigEndian.Uint16(header[:]))
+
+	// we do not care about picking up any cipher. we pick the first one,
+	// so it is always should be present.
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read first cipher suite: %w", err)
+	}
+
+	hello.CipherSuite = binary.BigEndian.Uint16(header[:])
+
+	if _, err := io.CopyN(io.Discard, r, cipherSuiteLen-2); err != nil {
+		return nil, fmt.Errorf("cannot skip remaining cipher suites: %w", err)
+	}
+
+	if _, err := io.ReadFull(r, header[:1]); err != nil {
+		return nil, fmt.Errorf("cannot read compression methods length: %w", err)
+	}
+
+	if _, err := io.CopyN(io.Discard, r, int64(header[0])); err != nil {
+		return nil, fmt.Errorf("cannot skip compression methods: %w", err)
+	}
+
+	return hello, nil
+}
+
+func parseSNI(r io.Reader) ([]string, error) {
+	header := [2]byte{}
+
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return nil, fmt.Errorf("cannot read length of TLS extensions: %w", err)
+	}
+
+	extensionsLength := int64(binary.BigEndian.Uint16(header[:]))
+	buf := &bytes.Buffer{}
+	buf.Grow(int(extensionsLength))
+
+	if _, err := io.CopyN(buf, r, extensionsLength); err != nil {
+		return nil, fmt.Errorf("cannot read extensions: %w", err)
+	}
+
+	for buf.Len() > 0 {
+		// 00 00 - assigned value for extension "server name"
+		// 00 18 - 0x18 (24) bytes of "server name" extension data follows
+		// 00 16 - 0x16 (22) bytes of first (and only) list entry follows
+		// 00 - list entry is type 0x00 "DNS hostname"
+		// 00 13 - 0x13 (19) bytes of hostname follows
+		// 65 78 61 ... 6e 65 74 - "example.ulfheim.net"
+
+		// 00 00 - assigned value for extension "server name"
+		extTypeB := buf.Next(2)
+		if len(extTypeB) != 2 {
+			return nil, fmt.Errorf("cannot read extension type: %v", extTypeB)
+		}
+
+		// 00 18 - 0x18 (24) bytes of "server name" extension data follows
+		lengthB := buf.Next(2)
+		if len(lengthB) != 2 {
+			return nil, fmt.Errorf("cannot read extension %v length: %v", extTypeB, lengthB)
+		}
+		length := int(binary.BigEndian.Uint16(lengthB))
+
+		extDataB := buf.Next(length)
+		if len(extDataB) != length {
+			return nil, fmt.Errorf("cannot read extension %v data: len %d != %d", extTypeB, length, len(extDataB))
+		}
+
+		if !bytes.Equal(extTypeB, extTypeSNI[:]) {
+			continue
+		}
+
+		buf.Reset()
+		buf.Write(extDataB)
+
+		// 00 16 - 0x16 (22) bytes of first (and only) list entry follows
+		lengthB = buf.Next(2)
+		if len(lengthB) != 2 {
+			return nil, fmt.Errorf("cannot read the length of the SNI record: %v", lengthB)
+		}
+
+		length = int(binary.BigEndian.Uint16(lengthB))
+		if length == 0 {
+			return nil, nil
+		}
+
+		listType, err := buf.ReadByte()
+		if err != nil {
+			return nil, fmt.Errorf("cannot read SNI list type: %w", err)
+		}
+
+		// 00 - list entry is type 0x00 "DNS hostname"
+		if listType != sniDNSNamesListType {
+			return nil, fmt.Errorf("incorrect SNI list type %#x", listType)
+		}
+
+		names := []string{}
+
+		for buf.Len() > 0 {
+			// 00 13 - 0x13 (19) bytes of hostname follows
+			lengthB = buf.Next(2)
+			if len(lengthB) != 2 {
+				return nil, fmt.Errorf("incorrect length of the hostname: %v", lengthB)
+			}
+			length = int(binary.BigEndian.Uint16(lengthB))
+
+			name := buf.Next(length)
+			if len(name) != length {
+				return nil, fmt.Errorf("incorrect length of SNI hostname: len %d != %d", length, len(name))
+			}
+
+			names = append(names, string(name))
+		}
+
+		return names, nil
+	}
+
+	return nil, nil
+}

mtglib/internal/tls/fake/client_side_fuzz_test.go

@@ -0,0 +1,48 @@
+package fake_test
+
+import (
+	"bytes"
+	"testing"
+	"time"
+
+	"github.com/9seconds/mtg/v2/internal/testlib"
+	"github.com/9seconds/mtg/v2/mtglib"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls/fake"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+type connMock struct {
+	testlib.EssentialsConnMock
+
+	readBuf *bytes.Buffer
+}
+
+func (f *connMock) Read(p []byte) (int, error) {
+	return f.readBuf.Read(p)
+}
+
+func FuzzReadClientHello(f *testing.F) {
+	seed := [248]byte{}
+
+	secret, err := mtglib.ParseSecret(
+		"ee367a189aee18fa31c190054efd4a8e9573746f726167652e676f6f676c65617069732e636f6d",
+	)
+	require.NoError(f, err)
+
+	f.Add(seed[:])
+
+	f.Fuzz(func(t *testing.T, value []byte) {
+		r := &connMock{
+			readBuf: bytes.NewBuffer(value),
+		}
+		r.
+			On("SetReadDeadline", mock.AnythingOfType("time.Time")).
+			Twice().
+			Return(nil)
+
+		_, err := fake.ReadClientHello(r, secret.Key[:], secret.Host, time.Hour)
+		assert.Error(t, err)
+	})
+}

mtglib/internal/tls/fake/client_side_snapshot_test.go

@@ -0,0 +1,153 @@
+package fake_test
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/9seconds/mtg/v2/mtglib"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls/fake"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+type clientHelloSnapshot struct {
+	Time        int    `json:"time"`
+	Random      string `json:"random"`
+	SessionID   string `json:"sessionId"`
+	Host        string `json:"host"`
+	CipherSuite int    `json:"cipherSuite"`
+	Full        string `json:"full"`
+}
+
+func (c clientHelloSnapshot) GetRandom() []byte {
+	data, _ := base64.StdEncoding.DecodeString(c.Random)
+
+	return data
+}
+
+func (c clientHelloSnapshot) GetSessionID() []byte {
+	data, _ := base64.StdEncoding.DecodeString(c.SessionID)
+
+	return data
+}
+
+func (c clientHelloSnapshot) GetCipherSuite() uint16 {
+	return uint16(c.CipherSuite)
+}
+
+func (c clientHelloSnapshot) GetFull() []byte {
+	data, _ := base64.StdEncoding.DecodeString(c.Full)
+
+	return data
+}
+
+type ParseClientHelloSnapshotTestSuite struct {
+	suite.Suite
+
+	secret mtglib.Secret
+}
+
+func (suite *ParseClientHelloSnapshotTestSuite) SetupSuite() {
+	parsed, err := mtglib.ParseSecret(
+		"ee367a189aee18fa31c190054efd4a8e9573746f726167652e676f6f676c65617069732e636f6d",
+	)
+	require.NoError(suite.T(), err)
+
+	suite.secret = parsed
+}
+
+func (suite *ParseClientHelloSnapshotTestSuite) makeConn(data []byte) *parseClientHelloConnMock {
+	readBuf := &bytes.Buffer{}
+	readBuf.Write(data)
+
+	connMock := &parseClientHelloConnMock{
+		readBuf: readBuf,
+	}
+
+	connMock.
+		On("SetReadDeadline", mock.AnythingOfType("time.Time")).
+		Twice().
+		Return(nil)
+
+	return connMock
+}
+
+func (suite *ParseClientHelloSnapshotTestSuite) TestSnapshotOk() {
+	files, err := os.ReadDir("testdata")
+	require.NoError(suite.T(), err)
+
+	for _, v := range files {
+		if !strings.HasPrefix(v.Name(), "client-hello-ok") {
+			continue
+		}
+
+		path := filepath.Join("testdata", v.Name())
+
+		suite.T().Run(v.Name(), func(t *testing.T) {
+			fileData, err := os.ReadFile(path)
+			assert.NoError(t, err)
+
+			snapshot := &clientHelloSnapshot{}
+			assert.NoError(t, json.Unmarshal(fileData, snapshot))
+
+			connMock := suite.makeConn(snapshot.GetFull())
+			defer connMock.AssertExpectations(t)
+
+			hello, err := fake.ReadClientHello(
+				connMock,
+				suite.secret.Key[:],
+				suite.secret.Host,
+				TolerateTime,
+			)
+			require.NoError(t, err)
+
+			assert.Equal(t, snapshot.GetRandom(), hello.Random[:])
+			assert.Equal(t, snapshot.GetSessionID(), hello.SessionID)
+			assert.Equal(t, snapshot.GetCipherSuite(), hello.CipherSuite)
+		})
+	}
+}
+
+func (suite *ParseClientHelloSnapshotTestSuite) TestSnapshotBad() {
+	files, err := os.ReadDir("testdata")
+	require.NoError(suite.T(), err)
+
+	for _, v := range files {
+		if !strings.HasPrefix(v.Name(), "client-hello-bad") {
+			continue
+		}
+
+		path := filepath.Join("testdata", v.Name())
+
+		suite.T().Run(v.Name(), func(t *testing.T) {
+			fileData, err := os.ReadFile(path)
+			assert.NoError(t, err)
+
+			snapshot := &clientHelloSnapshot{}
+			assert.NoError(t, json.Unmarshal(fileData, snapshot))
+
+			connMock := suite.makeConn(snapshot.GetFull())
+			defer connMock.AssertExpectations(t)
+
+			_, err = fake.ReadClientHello(
+				connMock,
+				suite.secret.Key[:],
+				suite.secret.Host,
+				TolerateTime,
+			)
+			assert.ErrorIs(t, err, fake.ErrBadDigest)
+		})
+	}
+}
+
+func TestParseClientHelloSnapshot(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ParseClientHelloSnapshotTestSuite{})
+}

mtglib/internal/tls/fake/client_side_test.go

@@ -0,0 +1,395 @@
+package fake_test
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"io"
+	"testing"
+	"time"
+
+	"github.com/9seconds/mtg/v2/internal/testlib"
+	"github.com/9seconds/mtg/v2/mtglib"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls/fake"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+const (
+	TolerateTime = 365 * 30 * 24 * time.Hour
+)
+
+type parseClientHelloConnMock struct {
+	testlib.EssentialsConnMock
+
+	readBuf *bytes.Buffer
+}
+
+func (m *parseClientHelloConnMock) Read(p []byte) (int, error) {
+	return m.readBuf.Read(p)
+}
+
+type ParseClientHelloTestSuite struct {
+	suite.Suite
+
+	secret   mtglib.Secret
+	readBuf  *bytes.Buffer
+	connMock *parseClientHelloConnMock
+}
+
+func (suite *ParseClientHelloTestSuite) SetupSuite() {
+	parsed, err := mtglib.ParseSecret("ee367a189aee18fa31c190054efd4a8e9573746f726167652e676f6f676c65617069732e636f6d")
+	require.NoError(suite.T(), err)
+
+	suite.secret = parsed
+}
+
+func (suite *ParseClientHelloTestSuite) SetupTest() {
+	suite.readBuf = &bytes.Buffer{}
+	suite.connMock = &parseClientHelloConnMock{
+		readBuf: suite.readBuf,
+	}
+
+	suite.connMock.
+		On("SetReadDeadline", mock.AnythingOfType("time.Time")).
+		Twice().
+		Return(nil)
+}
+
+func (suite *ParseClientHelloTestSuite) TearDownTest() {
+	suite.connMock.AssertExpectations(suite.T())
+}
+
+type ParseClientHello_TLSHeaderTestSuite struct {
+	ParseClientHelloTestSuite
+}
+
+func (suite *ParseClientHello_TLSHeaderTestSuite) TestEmpty() {
+	suite.connMock.ExpectedCalls = []*mock.Call{}
+	suite.connMock.
+		On("SetReadDeadline", mock.AnythingOfType("time.Time")).
+		Once().
+		Return(errors.New("fail"))
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "fail")
+}
+
+func (suite *ParseClientHello_TLSHeaderTestSuite) TestNothing() {
+	suite.connMock.ExpectedCalls = []*mock.Call{}
+	suite.connMock.
+		On("SetReadDeadline", mock.AnythingOfType("time.Time")).
+		Twice().
+		Return(nil)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorIs(err, io.EOF)
+}
+
+func (suite *ParseClientHello_TLSHeaderTestSuite) TestUnknownRecord() {
+	suite.readBuf.Write([]byte{
+		10,
+		3, 3,
+		0, 0,
+	})
+	suite.readBuf.WriteByte(10)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "unexpected record type 0xa")
+}
+
+func (suite *ParseClientHello_TLSHeaderTestSuite) TestUnknownProtocolVersion() {
+	suite.readBuf.Write([]byte{
+		tls.TypeHandshake,
+		3, 3,
+		0, 0,
+	})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "unexpected protocol version")
+}
+
+func (suite *ParseClientHello_TLSHeaderTestSuite) TestCannotReadRestOfRecord() {
+	suite.readBuf.Write([]byte{
+		tls.TypeHandshake,
+		3, 1,
+		0, 10,
+	})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorIs(err, io.EOF)
+}
+
+type ParseClientHelloHandshakeTestSuite struct {
+	ParseClientHelloTestSuite
+}
+
+func (suite *ParseClientHelloHandshakeTestSuite) SetupTest() {
+	suite.ParseClientHelloTestSuite.SetupTest()
+
+	suite.readBuf.Write([]byte{
+		tls.TypeHandshake,
+		3, 1,
+		0,
+	})
+}
+
+func (suite *ParseClientHelloHandshakeTestSuite) TestCannotReadHeader() {
+	suite.readBuf.Write([]byte{
+		1,
+		10,
+	})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read handshake header")
+}
+
+func (suite *ParseClientHelloHandshakeTestSuite) TestIncorrectHandshakeType() {
+	suite.readBuf.Write([]byte{
+		4,
+		10, 0, 0, 0,
+	})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "incorrect handshake type")
+}
+
+func (suite *ParseClientHelloHandshakeTestSuite) TestCannotReadHandshake() {
+	suite.readBuf.Write([]byte{
+		4 + 3,
+		10, 0, 0, 0,
+	})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorIs(err, io.EOF)
+}
+
+type ParseClientHelloHandshakeBodyTestSuite struct {
+	ParseClientHelloTestSuite
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) SetupTest() {
+	suite.ParseClientHelloTestSuite.SetupTest()
+
+	suite.readBuf.Write([]byte{
+		tls.TypeHandshake,
+		3, 1,
+		0,
+	})
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) writeBody(body []byte) {
+	suite.readBuf.WriteByte(byte(4 + len(body)))
+	suite.readBuf.Write([]byte{
+		fake.TypeHandshakeClient,
+		0, 0, byte(len(body)),
+	})
+	suite.readBuf.Write(body)
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadVersion() {
+	suite.writeBody(nil)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read client version")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadRandom() {
+	suite.writeBody([]byte{3, 3})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read client random")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadSessionIDLength() {
+	body := make([]byte, 2+fake.RandomLen)
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read session ID length")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadSessionID() {
+	body := make([]byte, 2+fake.RandomLen+1)
+	body[2+fake.RandomLen] = 32
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read session id")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadCipherSuiteLength() {
+	body := make([]byte, 2+fake.RandomLen+1)
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read cipher suite length")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadFirstCipherSuite() {
+	body := make([]byte, 2+fake.RandomLen+1+2)
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read first cipher suite")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotSkipRemainingCipherSuites() {
+	body := make([]byte, 2+fake.RandomLen+1+2+2)
+	binary.BigEndian.PutUint16(body[2+fake.RandomLen+1:], 4)
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot skip remaining cipher suites")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotReadCompressionMethodsLength() {
+	body := make([]byte, 2+fake.RandomLen+1+2+2)
+	binary.BigEndian.PutUint16(body[2+fake.RandomLen+1:], 2)
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read compression methods length")
+}
+
+func (suite *ParseClientHelloHandshakeBodyTestSuite) TestCannotSkipCompressionMethods() {
+	body := make([]byte, 2+fake.RandomLen+1+2+2+1)
+	binary.BigEndian.PutUint16(body[2+fake.RandomLen+1:], 2)
+	body[2+fake.RandomLen+1+2+2] = 1
+
+	suite.writeBody(body)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot skip compression methods")
+}
+
+type ParseClientHelloSNITestSuite struct {
+	ParseClientHelloTestSuite
+}
+
+func (suite *ParseClientHelloSNITestSuite) SetupTest() {
+	suite.ParseClientHelloTestSuite.SetupTest()
+
+	suite.readBuf.Write([]byte{
+		tls.TypeHandshake,
+		3, 1,
+		0,
+	})
+}
+
+func (suite *ParseClientHelloSNITestSuite) writeExtensions(extensions []byte) {
+	handshakeBodyLen := 41 + len(extensions)
+
+	suite.readBuf.WriteByte(byte(4 + handshakeBodyLen))
+	suite.readBuf.Write([]byte{
+		fake.TypeHandshakeClient,
+		0, 0, byte(handshakeBodyLen),
+	})
+
+	// version(2) + random(32) + sessionIDLen(1) + cipherSuiteLen(2) +
+	// cipherSuite(2) + compressionLen(1) + compression(1) = 41
+	body := make([]byte, 41)
+	binary.BigEndian.PutUint16(body[35:], 2)
+	body[39] = 1
+
+	suite.readBuf.Write(body)
+	suite.readBuf.Write(extensions)
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadExtensionsLength() {
+	suite.writeExtensions(nil)
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read length of TLS extensions")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadExtensions() {
+	suite.writeExtensions([]byte{0, 10})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read extensions")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadExtensionType() {
+	suite.writeExtensions([]byte{0, 1, 0xAB})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read extension type")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadExtensionLength() {
+	suite.writeExtensions([]byte{0, 2, 0xFF, 0xFF})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "length:")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadExtensionData() {
+	suite.writeExtensions([]byte{0, 4, 0xFF, 0xFF, 0, 5})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "data: len")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadSNIRecordLength() {
+	suite.writeExtensions([]byte{0, 5, 0, 0, 0, 1, 0xAB})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read the length of the SNI record")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadSNIListType() {
+	suite.writeExtensions([]byte{0, 6, 0, 0, 0, 2, 0, 1})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "cannot read SNI list type")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestIncorrectSNIListType() {
+	suite.writeExtensions([]byte{0, 7, 0, 0, 0, 3, 0, 1, 5})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "incorrect SNI list type")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadHostnameLength() {
+	suite.writeExtensions([]byte{0, 8, 0, 0, 0, 4, 0, 2, 0, 0xAB})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "incorrect length of the hostname")
+}
+
+func (suite *ParseClientHelloSNITestSuite) TestCannotReadHostname() {
+	suite.writeExtensions([]byte{0, 9, 0, 0, 0, 5, 0, 3, 0, 0, 5})
+
+	_, err := fake.ReadClientHello(suite.connMock, suite.secret.Key[:], suite.secret.Host, TolerateTime)
+	suite.ErrorContains(err, "incorrect length of SNI hostname")
+}
+
+func TestParseClientHelloTLSHeader(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ParseClientHello_TLSHeaderTestSuite{})
+}
+
+func TestParseClientHelloHandshake(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ParseClientHelloHandshakeTestSuite{})
+}
+
+func TestParseClientHelloHandshakeBody(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ParseClientHelloHandshakeBodyTestSuite{})
+}
+
+func TestParseClientHelloSNI(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ParseClientHelloSNITestSuite{})
+}

mtglib/internal/tls/fake/init.go

@@ -0,0 +1,16 @@
+package fake
+
+import (
+	"errors"
+	"time"
+)
+
+const (
+	ClientHelloReadTimeout = 5 * time.Second
+)
+
+var (
+	resetDeadline time.Time
+
+	ErrBadDigest = errors.New("incorrect client random")
+)

mtglib/internal/tls/fake/server_side.go

@@ -0,0 +1,135 @@
+package fake
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/binary"
+	"io"
+	rnd "math/rand/v2"
+
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"golang.org/x/crypto/curve25519"
+)
+
+const (
+	TypeHandshakeServer = 0x02
+	ChangeCipherValue   = 0x01
+
+	EllipticCurveLen = 32
+)
+
+var serverHelloSuffix = []byte{
+	0x00,       // no compression
+	0x00, 0x2e, // 46 bytes of data
+	0x00, 0x2b, // Extension - Supported Versions
+	0x00, 0x02, // 2 bytes are following
+	0x03, 0x04, // TLS 1.3
+	0x00, 0x33, // Extension - Key Share
+	0x00, 0x24, // 36 bytes
+	0x00, 0x1d, // x25519 curve
+	0x00, 0x20, // 32 bytes of key
+}
+
+func SendServerHello(w io.Writer, secret []byte, clientHello *ClientHello) error {
+	buf := &bytes.Buffer{}
+	buf.Grow(tls.MaxRecordSize)
+
+	generateServerHello(buf, clientHello)
+	generateChangeCipherValue(buf)
+	generateNoise(buf)
+
+	packet := buf.Bytes()
+	digest := hmac.New(sha256.New, secret)
+
+	digest.Write(clientHello.Random[:])
+	digest.Write(packet)
+	copy(packet[RandomOffset:], digest.Sum(nil))
+
+	_, err := w.Write(packet)
+
+	return err
+}
+
+func generateServerHello(buf *bytes.Buffer, hello *ClientHello) {
+	payload := acquireBuffer()
+	defer releaseBuffer(payload)
+
+	generateServerHelloPayload(payload, hello)
+
+	// 16 - type is 0x16 (handshake record)
+	// 03 03 - legacy protocol version of "3,3" (TLS 1.2)
+	// 00 7a - 0x7A (122) bytes of handshake message follows
+
+	// 16 - type is 0x16 (handshake record)
+	buf.WriteByte(tls.TypeHandshake)
+	// 03 03 - legacy protocol version of "3,3" (TLS 1.2)
+	buf.Write(tls.TLSVersion[:])
+	// 00 7a - 0x7A (122) bytes of handshake message follows
+	binary.Write(buf, binary.BigEndian, uint16(payload.Len())) //nolint: errcheck
+
+	payload.WriteTo(buf) //nolint: errcheck
+}
+
+func generateServerHelloPayload(buf *bytes.Buffer, hello *ClientHello) {
+	data := [4]byte{}
+
+	payload := acquireBuffer()
+	defer releaseBuffer(payload)
+
+	generateServerHelloHandshakePayload(payload, hello)
+
+	// 02 - handshake message type 0x02 (server hello)
+	// 00 00 76 - 0x76 (118) bytes of server hello data follows
+	buf.WriteByte(TypeHandshakeServer)
+	// 00 00 76 - 0x76 (118) bytes of server hello data follows
+	binary.BigEndian.PutUint32(data[:], uint32(payload.Len()))
+	buf.Write(data[1:])
+
+	payload.WriteTo(buf) //nolint: errcheck
+}
+
+func generateServerHelloHandshakePayload(buf *bytes.Buffer, hello *ClientHello) {
+	//  The unusual version number ("3,3" representing TLS 1.2) is due to
+	// TLS 1.0 being a minor revision of the SSL 3.0 protocol. Therefore
+	// TLS 1.0 is represented by "3,1", TLS 1.1 is "3,2", and so on.
+	buf.Write(tls.TLSVersion[:])
+
+	buf.Write(emptyRandom[:])
+
+	// 20 - 0x20 (32) bytes of session ID follow
+	// e0 e1 ... fe ff - session ID copied from Client Hello
+	buf.WriteByte(byte(len(hello.SessionID)))
+	buf.Write(hello.SessionID)
+
+	binary.Write(buf, binary.BigEndian, hello.CipherSuite) //nolint: errcheck
+
+	buf.Write(serverHelloSuffix)
+
+	scalar := [EllipticCurveLen]byte{}
+
+	if _, err := rand.Read(scalar[:]); err != nil {
+		panic(err)
+	}
+
+	curve, _ := curve25519.X25519(scalar[:], curve25519.Basepoint)
+	buf.Write(curve)
+}
+
+func generateChangeCipherValue(buf *bytes.Buffer) {
+	buf.WriteByte(tls.TypeChangeCipherSpec)
+	buf.Write(tls.TLSVersion[:])
+	binary.Write(buf, binary.BigEndian, uint16(1)) //nolint: errcheck
+	buf.WriteByte(ChangeCipherValue)
+}
+
+func generateNoise(buf *bytes.Buffer) {
+	data := make([]byte, int64(1024+rnd.IntN(3092)))
+
+	if _, err := rand.Read(data[:]); err != nil {
+		panic(err)
+	}
+
+	tls.WriteRecord(buf, data[:]) //nolint: errcheck
+}

mtglib/internal/tls/fake/server_side_test.go

@@ -0,0 +1,130 @@
+package fake_test
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"testing"
+
+	"github.com/9seconds/mtg/v2/mtglib"
+	"github.com/9seconds/mtg/v2/mtglib/internal/doppel"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls/fake"
+	"github.com/stretchr/testify/suite"
+)
+
+type SendServerHelloTestSuite struct {
+	suite.Suite
+
+	hello  *fake.ClientHello
+	buf    *bytes.Buffer
+	secret mtglib.Secret
+}
+
+func (suite *SendServerHelloTestSuite) SetupTest() {
+	suite.hello = &fake.ClientHello{
+		CipherSuite: 4867,
+		SessionID:   make([]byte, 32),
+	}
+
+	_, err := rand.Read(suite.hello.SessionID)
+	suite.NoError(err)
+
+	_, err = rand.Read(suite.hello.Random[:])
+	suite.NoError(err)
+
+	suite.buf = &bytes.Buffer{}
+	suite.secret = mtglib.GenerateSecret("google.com")
+}
+
+func (suite *SendServerHelloTestSuite) TestRecordStructure() {
+	err := fake.SendServerHello(suite.buf, suite.secret.Key[:], suite.hello)
+	suite.NoError(err)
+
+	var rec bytes.Buffer
+
+	recordType, _, err := tls.ReadRecord(suite.buf, &rec)
+	suite.NoError(err)
+	suite.Equal(byte(tls.TypeHandshake), recordType)
+
+	rec.Reset()
+
+	recordType, _, err = tls.ReadRecord(suite.buf, &rec)
+	suite.NoError(err)
+	suite.Equal(byte(tls.TypeChangeCipherSpec), recordType)
+
+	rec.Reset()
+
+	recordType, length, err := tls.ReadRecord(suite.buf, &rec)
+	suite.NoError(err)
+	suite.Equal(byte(tls.TypeApplicationData), recordType)
+	suite.Greater(length, int64(doppel.TLSRecordSizeStart))
+
+	suite.Empty(suite.buf.Bytes())
+}
+
+func (suite *SendServerHelloTestSuite) TestHMAC() {
+	err := fake.SendServerHello(suite.buf, suite.secret.Key[:], suite.hello)
+	suite.NoError(err)
+
+	packet := make([]byte, suite.buf.Len())
+	copy(packet, suite.buf.Bytes())
+
+	random := make([]byte, fake.RandomLen)
+	copy(random, packet[fake.RandomOffset:])
+	copy(packet[fake.RandomOffset:], make([]byte, fake.RandomLen))
+
+	mac := hmac.New(sha256.New, suite.secret.Key[:])
+	mac.Write(suite.hello.Random[:])
+	mac.Write(packet)
+
+	suite.Equal(random, mac.Sum(nil))
+}
+
+func (suite *SendServerHelloTestSuite) TestHandshakePayload() {
+	err := fake.SendServerHello(suite.buf, suite.secret.Key[:], suite.hello)
+	suite.NoError(err)
+
+	packet := suite.buf.Bytes()
+
+	// TLS record header: type(1) + version(2) + length(2)
+	suite.Equal(byte(tls.TypeHandshake), packet[0])
+	suite.Equal([]byte{3, 3}, packet[1:3])
+
+	// Handshake header: type(1) + uint24_length(3)
+	suite.Equal(byte(fake.TypeHandshakeServer), packet[5])
+
+	// ServerHello version
+	suite.Equal([]byte{3, 3}, packet[9:11])
+
+	// Session ID
+	sessionIDOffset := fake.RandomOffset + fake.RandomLen
+	suite.Equal(byte(len(suite.hello.SessionID)), packet[sessionIDOffset])
+	suite.Equal(suite.hello.SessionID, packet[sessionIDOffset+1:sessionIDOffset+1+len(suite.hello.SessionID)])
+}
+
+func (suite *SendServerHelloTestSuite) TestChangeCipherSpec() {
+	err := fake.SendServerHello(suite.buf, suite.secret.Key[:], suite.hello)
+	suite.NoError(err)
+
+	// Skip first record
+	var rec bytes.Buffer
+
+	_, _, err = tls.ReadRecord(suite.buf, &rec)
+	suite.NoError(err)
+
+	// Read ChangeCipherSpec record
+	rec.Reset()
+
+	recordType, length, err := tls.ReadRecord(suite.buf, &rec)
+	suite.NoError(err)
+	suite.Equal(byte(tls.TypeChangeCipherSpec), recordType)
+	suite.Equal(int64(1), length)
+	suite.Equal([]byte{fake.ChangeCipherValue}, rec.Bytes())
+}
+
+func TestSendServerHello(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &SendServerHelloTestSuite{})
+}

mtglib/internal/tls/fake/testdata/client-hello-bad-fa2e46cdb33e2a1b.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181365,
+  "random": "XvCPc3aAbHbhRLv0kUmy6BfPZOGvsused5/HNsKXEPs=",
+  "sessionId": "St2BZ2uHMFn3B2trD1jfdtpjoJOOg6JBeLhFcyCMCq4=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "FgMBAgABAAH8AwNe8I9zdoBsduFEu/SRSbLoF89k4a+y6x53n8c2wpcQ+yBK3YFna4cwWfcHa2sPWN922mOgk46DokF4uEVzIIAKrgA0EwMTARMCwCzAK8AkwCPACsAJzKnAMMAvwCjAJ8AUwBPMqACdAJwAPQA8ADUAL8AIwBIACgEAAX//AQABAAAAABsAGQAAFnN0b3JhZ2UuZ29vZ2xlYXBpcy5jb20AFwAAAA0AGAAWBAMIBAQBBQMCAwgFCAUFAQgGBgECAQAFAAUA0AAAADN0AAAAEgAAABAAMAAuAmgyBWgyLTE2BWgyLTE1BWgyLTE0CHNwZHkvMy4xBnNwZHkvMwhodHRwLzEuMQALAAIBAAAzACYAJAAdACAH/ugvH0kSUgAuwslL3UfZA3JTUfSiwrAhR6VWd2wvIgAtAAIBAQArAAkIAwQDAwMCAwEACgAKAAgAHQAXABgAGQAVAKEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
+}

mtglib/internal/tls/fake/testdata/client-hello-ok-19dfe38384b9884b.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181365,
+  "random": "XvCPc3aAbHbhRLv0kUmy6BfPZOGvsused5/HNsKXEPs=",
+  "sessionId": "St2BZ2uHMFn3B2trD1jfdtpjoJOOg6JBeLhFcyCMCq4=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "FgMBAgABAAH8AwNe8I9zdoBsduFEu/SRSbLoF89k4a+y6x53n8c2wpcQ+yBK3YFna4cwWfcHa2sPWN922mOgk46DokF4uEVzIIwKrgA0EwMTARMCwCzAK8AkwCPACsAJzKnAMMAvwCjAJ8AUwBPMqACdAJwAPQA8ADUAL8AIwBIACgEAAX//AQABAAAAABsAGQAAFnN0b3JhZ2UuZ29vZ2xlYXBpcy5jb20AFwAAAA0AGAAWBAMIBAQBBQMCAwgFCAUFAQgGBgECAQAFAAUBAAAAADN0AAAAEgAAABAAMAAuAmgyBWgyLTE2BWgyLTE1BWgyLTE0CHNwZHkvMy4xBnNwZHkvMwhodHRwLzEuMQALAAIBAAAzACYAJAAdACAH/ugvH0kSUgAuwslL3UfZA3JTUfSiwrAhR6VWd2wvIgAtAAIBAQArAAkIAwQDAwMCAwEACgAKAAgAHQAXABgAGQAVAKEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
+}

mtglib/internal/tls/fake/testdata/client-hello-ok-48f8a72a56f3174a.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181352,
+  "random": "oYEu33jl+zQbUKMtQbV1OHB0gXIM2y2aq9iY0QX12os=",
+  "sessionId": "FGqA3ZFYrSlj//xl7lammNn64K9/MK2mQ3HJUGvP+8g=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "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"
+}

mtglib/internal/tls/fake/testdata/client-hello-ok-651054256093c6cd.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181352,
+  "random": "5V5sSprk/tFIgy+x1BeKNGhLlFkqfggLpgN7GYOA1ro=",
+  "sessionId": "jxr4d6PXPDk+Lwx3WUp9wvj8TGlOxEdrRJ0ydyJ9+H8=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "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"
+}

mtglib/internal/tls/fake/testdata/client-hello-ok-79d01ef18a9d2621.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181365,
+  "random": "8xljlOhkDlkafEF5vu3e1r3fWvh8AX548wC3hLZ3szQ=",
+  "sessionId": "00uvDYKnFyZFKyf3HlLwWGCOyeHsPFiU5UZ+Fs5pDAU=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "FgMBAgABAAH8AwPzGWOU6GQOWRp8QXm+7d7Wvd9a+HwBfnjzALeEtnezNCDTS68NgqcXJkUrJ/ceUvBYYI7J4ew8WJTlRn4WzmkMBQA0EwMTARMCwCzAK8AkwCPACsAJzKnAMMAvwCjAJ8AUwBPMqACdAJwAPQA8ADUAL8AIwBIACgEAAX//AQABAAAAABsAGQAAFnN0b3JhZ2UuZ29vZ2xlYXBpcy5jb20AFwAAAA0AGAAWBAMIBAQBBQMCAwgFCAUFAQgGBgECAQAFAAUBAAAAADN0AAAAEgAAABAAMAAuAmgyBWgyLTE2BWgyLTE1BWgyLTE0CHNwZHkvMy4xBnNwZHkvMwhodHRwLzEuMQALAAIBAAAzACYAJAAdACD/0/vXjQ20rOPIPAF/32Y7LX4WNE8A8dM1D1bEc4qlXgAtAAIBAQArAAkIAwQDAwMCAwEACgAKAAgAHQAXABgAGQAVAKEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
+}

mtglib/internal/tls/fake/testdata/client-hello-ok-7a5569f05b118145.json

@@ -0,0 +1,8 @@
+{
+  "time": 1617181352,
+  "random": "zja3MLZ8WGSfsQRtPV75+tY6gbK3zKPi1Sy7SBBafg4=",
+  "sessionId": "qPut2yMqXa9zGLII/872SQ3d4Tfqo0uoDb7tpkRfBnA=",
+  "host": "storage.googleapis.com",
+  "cipherSuite": 4867,
+  "full": "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"
+}

mtglib/internal/tls/init_test.go

@@ -0,0 +1,30 @@
+package tls
+
+import (
+	"encoding/binary"
+
+	"github.com/stretchr/testify/mock"
+)
+
+type WriterMock struct {
+	mock.Mock
+}
+
+func (m *WriterMock) Write(p []byte) (int, error) {
+	args := m.Called(p)
+	return args.Int(0), args.Error(1)
+}
+
+// makeTLSRecord builds a raw TLS record from hardcoded offsets:
+// type(1) + version(2, {3,3}) + length(2, big-endian) + payload.
+func MakeTLSRecord(recordType byte, payload []byte) []byte {
+	buf := make([]byte, 5+len(payload))
+
+	buf[0] = recordType
+	buf[1] = 3
+	buf[2] = 3
+	binary.BigEndian.PutUint16(buf[3:5], uint16(len(payload)))
+	copy(buf[5:], payload)
+
+	return buf
+}

mtglib/internal/tls/utils.go

@@ -0,0 +1,48 @@
+package tls
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+func ReadRecord(r io.Reader, w io.Writer) (byte, int64, error) {
+	buf := [SizeHeader]byte{}
+
+	if _, err := io.ReadFull(r, buf[:]); err != nil {
+		return 0, 0, err
+	}
+
+	pVer := buf[SizeRecordType:]
+	pLen := pVer[SizeVersion:]
+
+	if !bytes.Equal(TLSVersion[:], pVer[:SizeVersion]) {
+		return 0, 0, fmt.Errorf("incorrect tls version %v", pVer)
+	}
+
+	length := int64(binary.BigEndian.Uint16(pLen[:SizeSize]))
+	_, err := io.CopyN(w, r, length)
+
+	return buf[0], length, err
+}
+
+func WriteRecord(w io.Writer, payload []byte) error {
+	buf := [MaxRecordSize]byte{}
+	buf[0] = TypeApplicationData
+
+	bufV := buf[SizeRecordType:]
+	copy(bufV[:SizeVersion], TLSVersion[:])
+
+	bufS := bufV[SizeVersion:]
+	binary.BigEndian.PutUint16(bufS[:SizeSize], uint16(len(payload)))
+
+	bufP := buf[SizeHeader:]
+	if n := copy(bufP, payload); n != len(payload) {
+		return fmt.Errorf("copied %d bytes of payload instead of %d", n, len(payload))
+	}
+
+	_, err := w.Write(buf[:SizeHeader+len(payload)])
+
+	return err
+}

mtglib/internal/tls/utils_test.go

@@ -0,0 +1,125 @@
+package tls
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type UtilsTestSuite struct {
+	suite.Suite
+
+	dst *bytes.Buffer
+}
+
+func (suite *UtilsTestSuite) SetupTest() {
+	suite.dst = &bytes.Buffer{}
+}
+
+func (suite *UtilsTestSuite) TestReadRecord() {
+	payload := []byte("hello world")
+	raw := MakeTLSRecord(0x17, payload)
+
+	recordType, length, err := ReadRecord(bytes.NewReader(raw), suite.dst)
+
+	suite.NoError(err)
+	suite.Equal(byte(0x17), recordType)
+	suite.Equal(int64(len(payload)), length)
+	suite.Equal(payload, suite.dst.Bytes())
+}
+
+func (suite *UtilsTestSuite) TestReadRecordChangeCipherSpec() {
+	payload := []byte{1}
+	raw := MakeTLSRecord(0x14, payload)
+
+	recordType, length, err := ReadRecord(bytes.NewReader(raw), suite.dst)
+
+	suite.NoError(err)
+	suite.Equal(byte(0x14), recordType)
+	suite.Equal(int64(1), length)
+}
+
+func (suite *UtilsTestSuite) TestReadRecordRejectsWrongVersion() {
+	record := []byte{0x17, 3, 1, 0, 5, 0, 0, 0, 0, 0}
+
+	_, _, err := ReadRecord(bytes.NewReader(record), suite.dst)
+	suite.ErrorContains(err, "incorrect tls version")
+}
+
+func (suite *UtilsTestSuite) TestReadRecordEmptyReader() {
+	_, _, err := ReadRecord(bytes.NewReader(nil), suite.dst)
+	suite.Error(err)
+}
+
+func (suite *UtilsTestSuite) TestReadRecordTruncatedHeader() {
+	_, _, err := ReadRecord(bytes.NewReader([]byte{0x17, 3}), suite.dst)
+	suite.Error(err)
+}
+
+func (suite *UtilsTestSuite) TestReadRecordTruncatedPayload() {
+	raw := MakeTLSRecord(0x17, []byte("full payload"))
+	truncated := raw[:5+3]
+
+	_, _, err := ReadRecord(bytes.NewReader(truncated), suite.dst)
+	suite.Error(err)
+}
+
+func (suite *UtilsTestSuite) TestWriteRecord() {
+	payload := []byte("hello world")
+
+	err := WriteRecord(suite.dst, payload)
+	suite.NoError(err)
+
+	written := suite.dst.Bytes()
+	suite.Equal(byte(0x17), written[0])
+	suite.Equal([]byte{3, 3}, written[1:3])
+
+	length := binary.BigEndian.Uint16(written[3:5])
+	suite.Equal(uint16(len(payload)), length)
+	suite.Equal(payload, written[5:])
+}
+
+func (suite *UtilsTestSuite) TestWriteRecordRoundTrip() {
+	payload := []byte("round trip test")
+
+	var wire bytes.Buffer
+
+	err := WriteRecord(&wire, payload)
+	suite.NoError(err)
+
+	var recovered bytes.Buffer
+
+	recordType, length, err := ReadRecord(&wire, &recovered)
+
+	suite.NoError(err)
+	suite.Equal(byte(0x17), recordType)
+	suite.Equal(int64(len(payload)), length)
+	suite.Equal(payload, recovered.Bytes())
+}
+
+func (suite *UtilsTestSuite) TestWriteRecordPropagatesError() {
+	m := &WriterMock{}
+	m.
+		On("Write", mock.AnythingOfType("[]uint8")).
+		Once().
+		Return(0, errors.New("dist full"))
+
+	err := WriteRecord(m, []byte("data"))
+	suite.Error(err)
+
+	m.AssertExpectations(suite.T())
+}
+
+func (suite *UtilsTestSuite) TestWriteRecordPayloadTooLarge() {
+	err := WriteRecord(suite.dst, make([]byte, MaxRecordPayloadSize+1))
+	suite.Error(err)
+}
+
+func TestUtils(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &UtilsTestSuite{})
+}

mtglib/proxy.go

@@ -11,10 +11,11 @@ import (
 
 	"github.com/9seconds/mtg/v2/essentials"
 	"github.com/9seconds/mtg/v2/mtglib/internal/dc"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
-	"github.com/9seconds/mtg/v2/mtglib/internal/faketls/record"
+	"github.com/9seconds/mtg/v2/mtglib/internal/doppel"
 	"github.com/9seconds/mtg/v2/mtglib/internal/obfuscation"
 	"github.com/9seconds/mtg/v2/mtglib/internal/relay"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
+	"github.com/9seconds/mtg/v2/mtglib/internal/tls/fake"
 	"github.com/panjf2000/ants/v2"
 )
 
@@ -32,6 +33,7 @@ type Proxy struct {
 	workerPool                  *ants.PoolWithFunc
 	telegram                    *dc.Telegram
 	configUpdater               *dc.PublicConfigUpdater
+	doppelGanger                *doppel.Ganger
 	clientObfuscatror           obfuscation.Obfuscator
 
 	secret          Secret
@@ -80,15 +82,22 @@ func (p *Proxy) ServeConn(conn essentials.Conn) {
 		return
 	}
 
-	if err := p.doObfuscatedHandshake(ctx); err != nil {
-		p.logger.InfoError("obfuscated handshake is failed", err)
+	clientConn, err := p.doppelGanger.NewConn(ctx.clientConn)
+	if err != nil {
+		ctx.logger.InfoError("cannot wrap into doppelganger connection", err)
+		return
+	}
+	defer clientConn.Stop()
 
+	ctx.clientConn = clientConn
+
+	if err := p.doObfuscatedHandshake(ctx); err != nil {
+		ctx.logger.InfoError("obfuscated handshake is failed", err)
 		return
 	}
 
 	if err := p.doTelegramCall(ctx); err != nil {
-		p.logger.WarningError("cannot dial to telegram", err)
-
+		ctx.logger.WarningError("cannot dial to telegram", err)
 		return
 	}
 
@@ -155,59 +164,40 @@ func (p *Proxy) Shutdown() {
 	p.streamWaitGroup.Wait()
 	p.workerPool.Release()
 	p.configUpdater.Wait()
+	p.doppelGanger.Shutdown()
 
 	p.allowlist.Shutdown()
 	p.blocklist.Shutdown()
 }
 
 func (p *Proxy) doFakeTLSHandshake(ctx *streamContext) bool {
-	rec := record.AcquireRecord()
-	defer record.ReleaseRecord(rec)
-
 	rewind := newConnRewind(ctx.clientConn)
 
-	if err := rec.Read(rewind); err != nil {
-		p.logger.InfoError("cannot read client hello", err)
-		p.doDomainFronting(ctx, rewind)
-
-		return false
-	}
-
-	hello, err := faketls.ParseClientHello(p.secret.Key[:], rec.Payload.Bytes())
+	clientHello, err := fake.ReadClientHello(
+		rewind,
+		p.secret.Key[:],
+		p.secret.Host,
+		p.tolerateTimeSkewness,
+	)
 	if err != nil {
-		p.logger.InfoError("cannot parse client hello", err)
-		p.doDomainFronting(ctx, rewind)
-
-		return false
-	}
-
-	if err := hello.Valid(p.secret.Host, p.tolerateTimeSkewness); err != nil {
-		p.logger.
-			BindStr("hostname", hello.Host).
-			BindStr("hello-time", hello.Time.String()).
-			InfoError("invalid faketls client hello", err)
+		p.logger.InfoError("cannot read client hello", err)
 		p.doDomainFronting(ctx, rewind)
-
 		return false
 	}
 
-	if p.antiReplayCache.SeenBefore(hello.SessionID) {
+	if p.antiReplayCache.SeenBefore(clientHello.SessionID) {
 		p.logger.Warning("replay attack has been detected!")
 		p.eventStream.Send(p.ctx, NewEventReplayAttack(ctx.streamID))
 		p.doDomainFronting(ctx, rewind)
-
 		return false
 	}
 
-	if err := faketls.SendWelcomePacket(rewind, p.secret.Key[:], hello); err != nil {
+	if err := fake.SendServerHello(ctx.clientConn, p.secret.Key[:], clientHello); err != nil {
 		p.logger.InfoError("cannot send welcome packet", err)
-
 		return false
 	}
 
-	ctx.clientConn = &faketls.Conn{
-		Conn: ctx.clientConn,
-	}
+	ctx.clientConn = tls.New(ctx.clientConn, true, false)
 
 	return true
 }
@@ -282,13 +272,16 @@ func (p *Proxy) doDomainFronting(ctx *streamContext, conn *connRewind) {
 	p.eventStream.Send(p.ctx, NewEventDomainFronting(ctx.streamID))
 	conn.Rewind()
 
-	frontConn, err := p.network.DialContext(ctx, "tcp", p.DomainFrontingAddress())
+	nativeDialer := p.network.NativeDialer()
+	fConn, err := nativeDialer.DialContext(ctx, "tcp", p.DomainFrontingAddress())
 	if err != nil {
 		p.logger.WarningError("cannot dial to the fronting domain", err)
 
 		return
 	}
 
+	frontConn := essentials.WrapNetConn(fConn)
+
 	if p.domainFrontingProxyProtocol {
 		frontConn = newConnProxyProtocol(ctx.clientConn, frontConn)
 	}
@@ -338,6 +331,15 @@ func NewProxy(opts ProxyOpts) (*Proxy, error) {
 		tolerateTimeSkewness:     opts.getTolerateTimeSkewness(),
 		allowFallbackOnUnknownDC: opts.AllowFallbackOnUnknownDC,
 		telegram:                 tg,
+		doppelGanger: doppel.NewGanger(
+			ctx,
+			opts.Network,
+			logger.Named("doppelganger"),
+			opts.DoppelGangerEach,
+			int(opts.DoppelGangerPerRaid),
+			opts.DoppelGangerURLs,
+			opts.DoppelGangerDRS,
+		),
 		configUpdater: dc.NewPublicConfigUpdater(
 			tg,
 			updatersLogger.Named("public-config"),
@@ -349,6 +351,8 @@ func NewProxy(opts ProxyOpts) (*Proxy, error) {
 		domainFrontingProxyProtocol: opts.DomainFrontingProxyProtocol,
 	}
 
+	proxy.doppelGanger.Run()
+
 	if opts.AutoUpdate {
 		proxy.configUpdater.Run(ctx, dc.PublicConfigUpdateURLv4, "tcp4")
 		proxy.configUpdater.Run(ctx, dc.PublicConfigUpdateURLv6, "tcp6")

mtglib/proxy_opts.go

@@ -142,6 +142,24 @@ type ProxyOpts struct {
 	//
 	// OBSOLETE and DEPRECATED. Ignored.
 	DCOverrides map[int][]string
+
+	// DoppelGangerURLs is a list of URLs that should be crawled by
+	// mtg to calculate parameters for statistical distribution of a
+	// traffic for fronting domains. If nothing is given, then predefined
+	// statistics is going to be used.
+	DoppelGangerURLs []string
+
+	// DoppelGangerPerRaid defines how many time each URL from
+	// DoppelGangerURLs list should be crawled per raid. We recommend to
+	// have this number ~10.
+	DoppelGangerPerRaid uint
+
+	// DoppelGangerEach defines a time period between each raid. We recommend
+	// to use hours here.
+	DoppelGangerEach time.Duration
+
+	// DoppelGangerDRS defines if TLS Dynamic Record Sizing is active.
+	DoppelGangerDRS bool
 }
 
 func (p ProxyOpts) valid() error {

network/network.go

@@ -60,6 +60,10 @@ func (n *network) DialContext(ctx context.Context, protocol, address string) (es
 	return nil, fmt.Errorf("cannot dial to %s:%s: %w", protocol, address, err)
 }
 
+func (n *network) NativeDialer() *net.Dialer {
+	return &net.Dialer{}
+}
+
 func (n *network) MakeHTTPClient(dialFunc func(ctx context.Context,
 	network, address string) (essentials.Conn, error),
 ) *http.Client {

network/v2/base_network_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"testing"
 
+	"github.com/9seconds/mtg/v2/mtglib"
 	"github.com/9seconds/mtg/v2/network/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/suite"
@@ -12,7 +13,7 @@ import (
 type BaseNetworkTestSuite struct {
 	EchoServerTestSuite
 
-	net network.Network
+	net mtglib.Network
 }
 
 func (suite *BaseNetworkTestSuite) SetupSuite() {

network/v2/init.go

@@ -11,10 +11,7 @@ package network
 
 import (
 	"errors"
-	"net"
 	"time"
-
-	"github.com/9seconds/mtg/v2/mtglib"
 )
 
 const (
@@ -31,15 +28,12 @@ const (
 	// probes.
 	DefaultTCPKeepAlivePeriod = 10 * time.Second
 
+	// User Agent to use in HTTP client.
+	UserAgent = "curl/8.5.0"
+
 	// tcpLingerTimeout defines a number of seconds to wait for sending
 	// unacknowledged data.
 	tcpLingerTimeout = 1
 )
 
 var ErrCannotDial = errors.New("cannot dial to any address")
-
-type Network interface {
-	mtglib.Network
-
-	NativeDialer() *net.Dialer
-}

network/v2/multi_network.go

@@ -8,10 +8,11 @@ import (
 	"net/http"
 
 	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib"
 )
 
 type multiNetwork struct {
-	networks []Network
+	networks []mtglib.Network
 }
 
 func (m multiNetwork) Dial(network, address string) (essentials.Conn, error) {
@@ -22,7 +23,7 @@ func (m multiNetwork) DialContext(ctx context.Context, network, address string)
 	networks := m.networks
 
 	if len(networks) > 1 {
-		networks = make([]Network, len(m.networks))
+		networks = make([]mtglib.Network, len(m.networks))
 		copy(networks, m.networks)
 
 		rand.Shuffle(len(m.networks), func(i, j int) {
@@ -59,7 +60,7 @@ func (m multiNetwork) MakeHTTPClient(
 	return m.networks[0].MakeHTTPClient(dialFunc)
 }
 
-func Join(networks ...Network) (Network, error) {
+func Join(networks ...mtglib.Network) (mtglib.Network, error) {
 	if len(networks) == 0 {
 		return nil, errors.New("cannot join no networks")
 	}

network/v2/network.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib"
 )
 
 type network struct {
@@ -70,11 +71,15 @@ func New(
 	tcpTimeout,
 	httpTimeout,
 	idleTimeout time.Duration,
-) Network {
+) mtglib.Network {
 	if dnsResolver == nil {
 		dnsResolver = net.DefaultResolver
 	}
 
+	if userAgent == "" {
+		userAgent = UserAgent
+	}
+
 	return &network{
 		Dialer: net.Dialer{
 			Timeout:       tcpTimeout,

network/v2/proxy_network.go

@@ -6,11 +6,12 @@ import (
 	"net/url"
 
 	"github.com/9seconds/mtg/v2/essentials"
+	"github.com/9seconds/mtg/v2/mtglib"
 	"golang.org/x/net/proxy"
 )
 
 type proxyNetwork struct {
-	Network
+	mtglib.Network
 	client proxy.ContextDialer
 }
 
@@ -23,7 +24,7 @@ func (p proxyNetwork) DialContext(ctx context.Context, network, address string)
 	return essentials.WrapNetConn(conn), nil
 }
 
-func NewProxyNetwork(base Network, proxyURL *url.URL) (*proxyNetwork, error) {
+func NewProxyNetwork(base mtglib.Network, proxyURL *url.URL) (*proxyNetwork, error) {
 	socks, err := proxy.FromURL(proxyURL, base.NativeDialer())
 	if err != nil {
 		return nil, fmt.Errorf("cannot build proxy dialer: %w", err)

network/v2/socks_proxy_test.go

@@ -6,6 +6,7 @@ import (
 	"sync"
 	"testing"
 
+	"github.com/9seconds/mtg/v2/mtglib"
 	"github.com/9seconds/mtg/v2/network/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -17,7 +18,7 @@ type SocksProxyTestSuite struct {
 	EchoServerTestSuite
 
 	wg          sync.WaitGroup
-	baseNetwork network.Network
+	baseNetwork mtglib.Network
 
 	noAuthURL *url.URL
 	authURL   *url.URL
@@ -85,7 +86,7 @@ func (suite *SocksProxyTestSuite) TestRead() {
 
 	for name, proxies := range testData {
 		suite.T().Run(name, func(t *testing.T) {
-			proxyNetworks := []network.Network{}
+			proxyNetworks := []mtglib.Network{}
 
 			for _, u := range proxies {
 				value, err := network.NewProxyNetwork(suite.baseNetwork, u)