Add rpc proxy flags

mtproto/rpc/rpc_proxy_flags.go

@@ -0,0 +1,51 @@
+package rpc
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"github.com/9seconds/mtg/mtproto"
+)
+
+type RPCProxyRequestFlags uint32
+
+const (
+	RPCProxyRequestFlagsHasAdTag     RPCProxyRequestFlags = 0x8
+	RPCProxyRequestFlagsEncrypted                         = 0x2
+	RPCProxyRequestFlagsMagic                             = 0x1000
+	RPCProxyRequestFlagsExtMode2                          = 0x20000
+	RPCProxyRequestFlagsIntermediate                      = 0x20000000
+	RPCProxyRequestFlagsAbdridged                         = 0x40000000
+	RPCProxyRequestFlagsQuickAck                          = 0x80000000
+)
+
+var rpcProxyRequestFlagsEncryptedPrefix [8]byte
+
+func (r RPCProxyRequestFlags) Bytes() []byte {
+	converted := make([]byte, 4)
+	binary.LittleEndian.PutUint32(converted, uint32(r))
+
+	return converted
+}
+
+func NewRPCRproxyRequestFlags(connectionType mtproto.ConnectionType, quickAck bool, message []byte) RPCProxyRequestFlags {
+	flags := RPCProxyRequestFlagsHasAdTag
+	flags |= RPCProxyRequestFlagsMagic
+	flags |= RPCProxyRequestFlagsExtMode2
+
+	switch connectionType {
+	case mtproto.ConnectionTypeAbridged:
+		flags |= RPCProxyRequestFlagsAbdridged
+	case mtproto.ConnectionTypeIntermediate:
+		flags |= RPCProxyRequestFlagsIntermediate
+	}
+
+	if quickAck {
+		flags |= RPCProxyRequestFlagsQuickAck
+	}
+	if bytes.HasPrefix(message, rpcProxyRequestFlagsEncryptedPrefix[:]) {
+		flags |= RPCProxyRequestFlagsEncrypted
+	}
+
+	return flags
+}