Merge pull request #76 from 9seconds/replay

Base prevention of replay attacks on proxy

README.md

 ```
 
 
+## Antireplay cache
+
+In order to prevent replay attacks, we have internal storage of first
+frames messages for connected clients. These frames are generated
+randomly by design and we have negligible possibility of duplication
+(probability is 1/(2^64)) but it could be quite effective in order to
+prevent replays.
+
+
 ## Environment variables
 
 It is possible to configure this tool using environment variables. You
 can configure any flag but not secret or adtag. Here is the list of
 supported environment variables:
 
-| Environment variable     | Corresponding flags    | Default value                     | Description                                                                                                                                                                                                                                                                |
-|--------------------------|------------------------|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `MTG_DEBUG`              | `-d`, `--debug`        | `false`                           | Run in debug mode. Usually, you need to run in this mode  only if you develop this tool or its maintainer is asking you to provide  logs with such verbosity.                                                                                                              |
-| `MTG_VERBOSE`            | `-v`, `--verbose`      | `false`                           | Run in verbose mode. This is way less chatty than debug mode.                                                                                                                                                                                                              |
-| `MTG_IP`                 | `-b`, `--bind-ip`      | `127.0.0.1`                       | Which IP should we bind to. As usual, `0.0.0.0` means that we want to listen on all interfaces. Also, 4 zeroes will bind to both IPv4 and IPv6.                                                                                                                            |
-| `MTG_PORT`               | `-p`, `--bind-port`    | `3128`                            | Which port should we bind to (listen on).                                                                                                                                                                                                                                  |
-| `MTG_IPV4`               | `-4`, `--public-ipv4`  | [Autodetect](https://ifconfig.co) | IPv4 address of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv4 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies. |
-| `MTG_IPV4_PORT`          | `--public-ipv4-port`   | Value of `--bind-port`            | Which port should be public of IPv4 interface. This affects only generated links and should be changed only if you NAT your proxy or run it in a docker container.                                                                                                         |
-| `MTG_IPV6`               | `-6`, `--public-ipv6`  | [Autodetect](https://ifconfig.co) | IPv6 address of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv6 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies. |
-| `MTG_IPV6_PORT`          | `--public-ipv6-port`   | Value of `--bind-port`            | Which port should be public of IPv6 interface. This affects only generated links and should be changed only if you NAT your proxy or run it in a docker container.                                                                                                         |
-| `MTG_STATS_IP`           | `-t`, `--stats-ip`     | `127.0.0.1`                       | Which IP should we bind the internal statistics HTTP server.                                                                                                                                                                                                               |
-| `MTG_STATS_PORT`         | `-q`, `--stats-port`   | `3129`                            | Which port should we bind the internal statistics HTTP server.                                                                                                                                                                                                             |
-| `MTG_STATSD_IP`          | `--statsd-ip`          |                                   | IP/host addresses of statsd service. No defaults, by defaults we do not send anything there.                                                                                                                                                                               |
-| `MTG_STATSD_PORT`        | `--statsd-port`        | `8125`                            | Which port should we use to work with statsd.                                                                                                                                                                                                                              |
-| `MTG_STATSD_NETWORK`     | `--statsd-network`     | `udp`                             | Which protocol should we use to work with statsd. Possible options are `udp` and `tcp`.                                                                                                                                                                                    |
-| `MTG_STATSD_PREFIX`      | `--statsd-prefix`      | `mtg`                             | Which bucket prefix we should use. For example, if you set `mtg`, then metric `traffic.ingress` would be send as `mtg.traffic.ingress`.                                                                                                                                    |
-| `MTG_STATSD_TAGS_FORMAT` | `--statsd-tags-format` |                                   | Which tags format we should use. By default, we are using default vanilla statsd tags format but if you want to send directly to InfluxDB or Datadog, please specify it there. Possible options are `influxdb` and `datadog`.                                              |
-| `MTG_STATSD_TAGS`        | `--statsd-tags`        |                                   | Which tags should we send to statsd with our metrics. Please specify them as `key=value` pairs.                                                                                                                                                                            |
-| `MTG_PROMETHEUS_PREFIX`  | `--prometheus-prefix`  | `mtg`                             | Which namespace should be used for prometheus metrics.                                                                                                                                                                                                                     |
-| `MTG_BUFFER_WRITE`       | `-w`, `--write-buffer` | `65536`                           | The size of TCP write buffer in bytes. Write buffer is the buffer for messages which are going from client to Telegram.                                                                                                                                                    |
-| `MTG_BUFFER_READ`        | `-r`, `--read-buffer`  | `131072`                          | The size of TCP read buffer in bytes. Read buffer is the buffer for messages from Telegram to client.                                                                                                                                                                      |
-| `MTG_SECURE_ONLY`        | `-s`, `--secure-only`  | `false`                           | Support only clients with secure mode (i.e only clients with dd-secrets).                                                                                                                                                                                                  |
+| Environment variable          | Corresponding flags         | Default value                     | Description                                                                                                                                                                                                                                                                |
+|-------------------------------|-----------------------------|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `MTG_DEBUG`                   | `-d`, `--debug`             | `false`                           | Run in debug mode. Usually, you need to run in this mode  only if you develop this tool or its maintainer is asking you to provide  logs with such verbosity.                                                                                                              |
+| `MTG_VERBOSE`                 | `-v`, `--verbose`           | `false`                           | Run in verbose mode. This is way less chatty than debug mode.                                                                                                                                                                                                              |
+| `MTG_IP`                      | `-b`, `--bind-ip`           | `127.0.0.1`                       | Which IP should we bind to. As usual, `0.0.0.0` means that we want to listen on all interfaces. Also, 4 zeroes will bind to both IPv4 and IPv6.                                                                                                                            |
+| `MTG_PORT`                    | `-p`, `--bind-port`         | `3128`                            | Which port should we bind to (listen on).                                                                                                                                                                                                                                  |
+| `MTG_IPV4`                    | `-4`, `--public-ipv4`       | [Autodetect](https://ifconfig.co) | IPv4 address of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv4 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies. |
+| `MTG_IPV4_PORT`               | `--public-ipv4-port`        | Value of `--bind-port`            | Which port should be public of IPv4 interface. This affects only generated links and should be changed only if you NAT your proxy or run it in a docker container.                                                                                                         |
+| `MTG_IPV6`                    | `-6`, `--public-ipv6`       | [Autodetect](https://ifconfig.co) | IPv6 address of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv6 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies. |
+| `MTG_IPV6_PORT`               | `--public-ipv6-port`        | Value of `--bind-port`            | Which port should be public of IPv6 interface. This affects only generated links and should be changed only if you NAT your proxy or run it in a docker container.                                                                                                         |
+| `MTG_STATS_IP`                | `-t`, `--stats-ip`          | `127.0.0.1`                       | Which IP should we bind the internal statistics HTTP server.                                                                                                                                                                                                               |
+| `MTG_STATS_PORT`              | `-q`, `--stats-port`        | `3129`                            | Which port should we bind the internal statistics HTTP server.                                                                                                                                                                                                             |
+| `MTG_STATSD_IP`               | `--statsd-ip`               |                                   | IP/host addresses of statsd service. No defaults, by defaults we do not send anything there.                                                                                                                                                                               |
+| `MTG_STATSD_PORT`             | `--statsd-port`             | `8125`                            | Which port should we use to work with statsd.                                                                                                                                                                                                                              |
+| `MTG_STATSD_NETWORK`          | `--statsd-network`          | `udp`                             | Which protocol should we use to work with statsd. Possible options are `udp` and `tcp`.                                                                                                                                                                                    |
+| `MTG_STATSD_PREFIX`           | `--statsd-prefix`           | `mtg`                             | Which bucket prefix we should use. For example, if you set `mtg`, then metric `traffic.ingress` would be send as `mtg.traffic.ingress`.                                                                                                                                    |
+| `MTG_STATSD_TAGS_FORMAT`      | `--statsd-tags-format`      |                                   | Which tags format we should use. By default, we are using default vanilla statsd tags format but if you want to send directly to InfluxDB or Datadog, please specify it there. Possible options are `influxdb` and `datadog`.                                              |
+| `MTG_STATSD_TAGS`             | `--statsd-tags`             |                                   | Which tags should we send to statsd with our metrics. Please specify them as `key=value` pairs.                                                                                                                                                                            |
+| `MTG_PROMETHEUS_PREFIX`       | `--prometheus-prefix`       | `mtg`                             | Which namespace should be used for prometheus metrics.                                                                                                                                                                                                                     |
+| `MTG_BUFFER_WRITE`            | `-w`, `--write-buffer`      | `65536`                           | The size of TCP write buffer in bytes. Write buffer is the buffer for messages which are going from client to Telegram.                                                                                                                                                    |
+| `MTG_BUFFER_READ`             | `-r`, `--read-buffer`       | `131072`                          | The size of TCP read buffer in bytes. Read buffer is the buffer for messages from Telegram to client.                                                                                                                                                                      |
+| `MTG_SECURE_ONLY`             | `-s`, `--secure-only`       | `false`                           | Support only clients with secure mode (i.e only clients with dd-secrets).                                                                                                                                                                                                  |
+| `MTG_ANTIREPLAY_MAXSIZE`      | `anti-replay-max-size`      | `128`                             | Max size of antireplay cache in megabytes.                                                                                                                                                                                                                                 |
+| `MTG_ANTIREPLAY_EVICTIONTIME` | `anti-replay-eviction-time` | `168h`                            | Eviction time for antireplay cache entries.                                                                                                                                                                                                                                |
 
 Usually you want to modify only read/write buffer sizes. If you feel
 that proxy is slow, try to increase both sizes giving more priority to

antireplay/cache.go

+package antireplay
+
+import (
+	"github.com/allegro/bigcache"
+	"github.com/juju/errors"
+
+	"github.com/9seconds/mtg/config"
+)
+
+// Cache defines storage for obfuscated2 handshake frames.
+type Cache struct {
+	cache *bigcache.BigCache
+}
+
+func (a Cache) Add(frame []byte) {
+	a.cache.Set(string(frame), nil) // nolint: errcheck
+}
+
+func (a Cache) Has(frame []byte) bool {
+	_, err := a.cache.Get(string(frame))
+
+	return err == nil
+}
+
+func NewCache(config *config.Config) (Cache, error) {
+	cache, err := bigcache.NewBigCache(bigcache.Config{
+		Shards:           1024,
+		LifeWindow:       config.AntiReplayEvictionTime,
+		Hasher:           hasher{},
+		HardMaxCacheSize: config.AntiReplayMaxSize,
+	})
+	if err != nil {
+		return Cache{}, errors.Annotate(err, "Cannot make cache")
+	}
+
+	return Cache{cache}, nil
+}

antireplay/hasher.go

+package antireplay
+
+import "github.com/cespare/xxhash"
+
+type hasher struct{}
+
+func (h hasher) Sum64(value string) uint64 {
+	return xxhash.Sum64String(value)
+}

client/client.go

 	"context"
 	"net"
 
+	"github.com/9seconds/mtg/antireplay"
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/mtproto"
 	"github.com/9seconds/mtg/wrappers"
 
 // Init defines common method for initializing client connections.
 type Init func(context.Context, context.CancelFunc, net.Conn, string,
-	*config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error)
+	antireplay.Cache, *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error)

client/direct.go

 
 	"github.com/juju/errors"
 
+	"github.com/9seconds/mtg/antireplay"
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/mtproto"
 	"github.com/9seconds/mtg/obfuscated2"
 // DirectInit initializes client connection for proxy which connects to
 // Telegram directly.
 func DirectInit(ctx context.Context, cancel context.CancelFunc, socket net.Conn,
-	connID string, conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
+	connID string, antiReplayCache antireplay.Cache,
+	conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
 	tcpSocket := socket.(*net.TCPConn)
 	if err := tcpSocket.SetNoDelay(false); err != nil {
 		return nil, nil, errors.Annotate(err, "Cannot disable NO_DELAY to client socket")
 	if err != nil {
 		return nil, nil, errors.Annotate(err, "Cannot parse obfuscated frame")
 	}
+
+	if antiReplayCache.Has([]byte(frame)) {
+		return nil, nil, errors.New("Replay attack is detected")
+	}
+	antiReplayCache.Add([]byte(frame))
+
 	connOpts.ConnectionProto = mtproto.ConnectionProtocolAny
 	connOpts.ClientAddr = conn.RemoteAddr()
 

client/middle.go

 	"context"
 	"net"
 
+	"github.com/9seconds/mtg/antireplay"
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/mtproto"
 	"github.com/9seconds/mtg/wrappers"
 // MiddleInit initializes client connection for proxy which has to
 // support promoted channels, connect to Telegram middle proxies etc.
 func MiddleInit(ctx context.Context, cancel context.CancelFunc, socket net.Conn,
-	connID string, conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
-	conn, opts, err := DirectInit(ctx, cancel, socket, connID, conf)
+	connID string, antiReplayCache antireplay.Cache,
+	conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
+	conn, opts, err := DirectInit(ctx, cancel, socket, connID, antiReplayCache, conf)
 	if err != nil {
 		return nil, nil, err
 	}

config/config.go

 	"fmt"
 	"net"
 	"strconv"
+	"time"
 
 	"github.com/juju/errors"
 	statsd "gopkg.in/alexcesaro/statsd.v2"
 	PublicIPv6 net.IP
 	StatsIP    net.IP
 
+	AntiReplayMaxSize      int
+	AntiReplayEvictionTime time.Duration
+
 	StatsD struct {
 		Addr       net.Addr
 		Prefix     string
 	statsdIP, statsdNetwork, statsdPrefix, statsdTagsFormat string,
 	statsdTags map[string]string, prometheusPrefix string,
 	secureOnly bool,
+	antiReplayMaxSize int, antiReplayEvictionTime time.Duration,
 	secret, adtag []byte) (*Config, error) {
 	secureMode := secureOnly
 	if bytes.HasPrefix(secret, []byte{0xdd}) && len(secret) == 17 {
 	}
 
 	conf := &Config{
-		Debug:           debug,
-		Verbose:         verbose,
-		SecureOnly:      secureOnly,
-		BindIP:          bindIP,
-		BindPort:        bindPort,
-		PublicIPv4:      publicIPv4,
-		PublicIPv4Port:  publicIPv4Port,
-		PublicIPv6:      publicIPv6,
-		PublicIPv6Port:  publicIPv6Port,
-		StatsIP:         statsIP,
-		StatsPort:       statsPort,
-		Secret:          secret,
-		AdTag:           adtag,
-		SecureMode:      secureMode,
-		ReadBufferSize:  int(readBufferSize),
-		WriteBufferSize: int(writeBufferSize),
+		Debug:                  debug,
+		Verbose:                verbose,
+		SecureOnly:             secureOnly,
+		BindIP:                 bindIP,
+		BindPort:               bindPort,
+		PublicIPv4:             publicIPv4,
+		PublicIPv4Port:         publicIPv4Port,
+		PublicIPv6:             publicIPv6,
+		PublicIPv6Port:         publicIPv6Port,
+		StatsIP:                statsIP,
+		StatsPort:              statsPort,
+		Secret:                 secret,
+		AdTag:                  adtag,
+		SecureMode:             secureMode,
+		ReadBufferSize:         int(readBufferSize),
+		WriteBufferSize:        int(writeBufferSize),
+		AntiReplayMaxSize:      antiReplayMaxSize,
+		AntiReplayEvictionTime: antiReplayEvictionTime,
 	}
 	conf.Prometheus.Prefix = prometheusPrefix
 

go.mod

 replace github.com/golang/lint => github.com/golang/lint v0.0.0-20190227174305-8f45f776aaf1
 
 require (
+	github.com/OneOfOne/xxhash v1.2.5 // indirect
+	github.com/allegro/bigcache v1.2.0
 	github.com/beevik/ntp v0.2.0
+	github.com/beorn7/perks v1.0.0 // indirect
+	github.com/cespare/xxhash v1.1.0
 	github.com/dustin/go-humanize v1.0.0
 	github.com/gofrs/uuid v3.2.0+incompatible
-	github.com/golang/protobuf v1.3.0 // indirect
+	github.com/golang/protobuf v1.3.1 // indirect
 	github.com/juju/errors v0.0.0-20190207033735-e65537c515d7
 	github.com/juju/loggo v0.0.0-20190212223446-d976af380377 // indirect
-	github.com/juju/testing v0.0.0-20180920084828-472a3e8b2073 // indirect
+	github.com/juju/testing v0.0.0-20190418112600-6570bd8f8541 // indirect
 	github.com/kr/pretty v0.1.0 // indirect
 	github.com/pkg/errors v0.8.1 // indirect
-	github.com/prometheus/client_golang v0.9.2
+	github.com/prometheus/client_golang v0.9.3-0.20190127221311-3c4408c8b829
 	github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90 // indirect
-	github.com/prometheus/common v0.2.0 // indirect
-	github.com/prometheus/procfs v0.0.0-20190227231451-bbced9601137 // indirect
+	github.com/prometheus/common v0.3.0 // indirect
+	github.com/prometheus/procfs v0.0.0-20190425082905-87a4384529e0 // indirect
+	github.com/spaolacci/murmur3 v1.1.0 // indirect
 	github.com/stretchr/testify v1.3.0
 	go.uber.org/atomic v1.3.2 // indirect
 	go.uber.org/multierr v1.1.0 // indirect
 	go.uber.org/zap v1.9.1
-	golang.org/x/net v0.0.0-20190228165749-92fc7df08ae7 // indirect
-	golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6 // indirect
+	golang.org/x/net v0.0.0-20190424112056-4829fb13d2c6 // indirect
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/alexcesaro/statsd.v2 v2.0.0
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect

go.sum

+github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/OneOfOne/xxhash v1.2.5 h1:zl/OfRA6nftbBK9qTohYBJ5xvw6C/oNKizR7cZGl3cI=
+github.com/OneOfOne/xxhash v1.2.5/go.mod h1:eZbhyaAYD41SGSSsnmcpxVoRiQ/MPUTjUdIIOT9Um7Q=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc h1:cAKDfWh5VpdgMhJosfJnn5/FoN2SRZ4p7fJNX58YPaU=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf h1:qet1QNfXsQxTZqLG4oE62mJzwPIB8+Tee4RNCL9ulrY=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/allegro/bigcache v1.2.0 h1:qDaE0QoF29wKBb3+pXFrJFy1ihe5OT9OiXhg1t85SxM=
+github.com/allegro/bigcache v1.2.0/go.mod h1:Cb/ax3seSYIx7SuZdm2G2xzfwmv3TPSk2ucNfQESPXM=
 github.com/beevik/ntp v0.2.0 h1:sGsd+kAXzT0bfVfzJfce04g+dSRfrs+tbQW8lweuYgw=
 github.com/beevik/ntp v0.2.0/go.mod h1:hIHWr+l3+/clUnF44zdK+CWW7fO8dR5cIylAQ76NRpg=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973 h1:xJ4a3vCFaGF/jqvzLMYoU8P317H5OQ+Via4RmuPwCS0=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
+github.com/beorn7/perks v1.0.0 h1:HWo1m869IqiPhD389kmkxeTalrjNbbJTC8LXupb+sl0=
+github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
+github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
+github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
-github.com/golang/protobuf v1.3.0 h1:kbxbvI4Un1LUWKxufD+BiE6AEExYYgkQLQmLFqA1LFk=
-github.com/golang/protobuf v1.3.0/go.mod h1:Qd/q+1AKNOZr9uGQzbzCmRO6sUih6GTPZv6a1/R87v0=
+github.com/golang/protobuf v1.3.1 h1:YF8+flBXS5eO826T4nzqPrxfhQThhXl0YzfuUPu4SBg=
+github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/juju/errors v0.0.0-20190207033735-e65537c515d7 h1:dMIPRDg6gi7CUp0Kj2+HxqJ5kTr1iAdzsXYIrLCNSmU=
 github.com/juju/errors v0.0.0-20190207033735-e65537c515d7/go.mod h1:W54LbzXuIE0boCoNJfwqpmkKJ1O4TCTZMetAt6jGk7Q=
 github.com/juju/loggo v0.0.0-20190212223446-d976af380377 h1:n6QjW3g5JNY3xPmIjFt6z1H6tFQA6BhwOC2bvTAm1YU=
 github.com/juju/loggo v0.0.0-20190212223446-d976af380377/go.mod h1:vgyd7OREkbtVEN/8IXZe5Ooef3LQePvuBm9UWj6ZL8U=
-github.com/juju/testing v0.0.0-20180920084828-472a3e8b2073 h1:WQM1NildKThwdP7qWrNAFGzp4ijNLw8RlgENkaI4MJs=
-github.com/juju/testing v0.0.0-20180920084828-472a3e8b2073/go.mod h1:63prj8cnj0tU0S9OHjGJn+b1h0ZghCndfnbQolrYTwA=
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main.go

 		Envar("MTG_SECURE_ONLY").
 		Bool()
 
+	antiReplayMaxSize = app.Flag("anti-replay-max-size",
+		"Max size of antireplay cache in megabytes.").
+		Envar("MTG_ANTIREPLAY_MAXSIZE").
+		Default("128").
+		Int()
+	antiReplayEvictionTime = app.Flag("anti-replay-eviction-time",
+		"Eviction time period for obfuscated2 handshakes").
+		Envar("MTG_ANTIREPLAY_EVICTIONTIME").
+		Default("168h").
+		Duration()
+
 	secret = app.Arg("secret", "Secret of this proxy.").Required().HexBytes()
 	adtag  = app.Arg("adtag", "ADTag of the proxy.").HexBytes()
 )
 		*bindPort, *publicIPv4Port, *publicIPv6Port, *statsPort, *statsdPort,
 		*statsdIP, *statsdNetwork, *statsdPrefix, *statsdTagsFormat,
 		*statsdTags, *prometheusPrefix, *secureOnly,
+		*antiReplayMaxSize, *antiReplayEvictionTime,
 		*secret, *adtag,
 	)
 	if err != nil {
 		panic(err)
 	}
 
-	server := proxy.NewProxy(conf)
+	server, err := proxy.NewProxy(conf)
+	if err != nil {
+		panic(err)
+	}
 	if err := server.Serve(); err != nil {
 		zap.S().Fatalw("Server stopped", "error", err)
 	}

proxy/proxy.go

 	"github.com/juju/errors"
 	"go.uber.org/zap"
 
+	"github.com/9seconds/mtg/antireplay"
 	"github.com/9seconds/mtg/client"
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/mtproto"
 
 // Proxy is a core of this program.
 type Proxy struct {
-	clientInit client.Init
-	tg         telegram.Telegram
-	conf       *config.Config
+	antiReplayCache antireplay.Cache
+	clientInit      client.Init
+	tg              telegram.Telegram
+	conf            *config.Config
 }
 
 // Serve runs TCP proxy server.
 
 	log.Infow("Client connected", "addr", conn.RemoteAddr())
 
-	clientConn, opts, err := p.clientInit(ctx, cancel, conn, connID, p.conf)
+	clientConn, opts, err := p.clientInit(ctx, cancel, conn, connID, p.antiReplayCache, p.conf)
 	if err != nil {
 		log.Errorw("Cannot initialize client connection", "error", err)
 		return
 }
 
 // NewProxy returns new proxy instance.
-func NewProxy(conf *config.Config) *Proxy {
+func NewProxy(conf *config.Config) (*Proxy, error) {
 	var clientInit client.Init
 	var tg telegram.Telegram
 
+	cache, err := antireplay.NewCache(conf)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot make proxy")
+	}
+
 	if conf.UseMiddleProxy() {
 		clientInit = client.MiddleInit
 		tg = telegram.NewMiddleTelegram(conf)
 	}
 
 	return &Proxy{
-		conf:       conf,
-		clientInit: clientInit,
-		tg:         tg,
-	}
+		antiReplayCache: cache,
+		conf:            conf,
+		clientInit:      clientInit,
+		tg:              tg,
+	}, nil
 }