Merge pull request #10 from 9seconds/channels

Promoted channels

Gopkg.lock

@@ -22,6 +22,12 @@
   revision = "346938d642f2ec3594ed81d874461961cd0faa76"
   version = "v1.1.0"
 
+[[projects]]
+  branch = "master"
+  name = "github.com/dustin/go-humanize"
+  packages = ["."]
+  revision = "02af3965c54e8cacf948b97fef38925c4120652c"
+
 [[projects]]
   branch = "master"
   name = "github.com/juju/errors"
@@ -80,6 +86,6 @@
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "24afdd6b64331aeba47fed75918d04032e13e404612cac107bad1d68a5038b72"
+  inputs-digest = "c4fdd3664f683342ad0c2509f4a8bcfe5b267a6e8cdaf36f70d39536bbf89834"
   solver-name = "gps-cdcl"
   solver-version = 1

Gopkg.toml

@@ -44,3 +44,7 @@
 [[constraint]]
   name = "github.com/satori/go.uuid"
   version = "1.2.0"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/dustin/go-humanize"

README.md

@@ -38,6 +38,18 @@ mtg is an implementation in golang which is intended to be:
 * **No management WebUI**
   This is an implementation of simple lightweight proxy. I won't do that.
 
+This proxy supports 2 modes of work: direct connection to Telegram and
+promoted channel mode. If you do not need promoted channels, I would
+recommend you to go with direct mode: this is way more robust.
+
+To run proxy in direct mode, all you need to do is just provide a
+secret. If you do not provide ADTag as a second parameter, promoted
+channels mode won't be activated.
+
+To get promoted channel, please contact
+[@MTProxybot|https://t.me/MTProxybot] and provide generated adtag as a
+second parameter.
+
 
 # How to build
 

client/client.go

@@ -1,12 +1,12 @@
 package client
 
 import (
-	"io"
 	"net"
 
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/wrappers"
 )
 
-// Init has to initialize client connection based on given config.
+// Init defines common method for initializing client connections.
-type Init func(net.Conn, *config.Config) (*mtproto.ConnectionOpts, io.ReadWriteCloser, error)
+type Init func(net.Conn, string, *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error)

client/direct.go

@@ -1,7 +1,6 @@
 package client
 
 import (
-	"io"
 	"net"
 	"time"
 
@@ -15,28 +14,42 @@ import (
 
 const (
 	handshakeTimeout = 10 * time.Second
+	readBufferSize   = 64 * 1024
+	writeBufferSize  = 64 * 1024
 )
 
-// DirectInit initializes client to access Telegram bypassing middleproxies.
+// DirectInit initializes client connection for proxy which connects to
-func DirectInit(conn net.Conn, conf *config.Config) (*mtproto.ConnectionOpts, io.ReadWriteCloser, error) {
+// Telegram directly.
-	if err := config.SetSocketOptions(conn); err != nil {
+func DirectInit(socket net.Conn, connID string, conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
-		return nil, nil, errors.Annotate(err, "Cannot set socket options")
+	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 := tcpSocket.SetReadBuffer(readBufferSize); err != nil {
+		return nil, nil, errors.Annotate(err, "Cannot set read buffer size of client socket")
+	}
+	if err := tcpSocket.SetWriteBuffer(writeBufferSize); err != nil {
+		return nil, nil, errors.Annotate(err, "Cannot set write buffer size of client socket")
 	}
 
-	conn.SetReadDeadline(time.Now().Add(handshakeTimeout)) // nolint: errcheck
+	socket.SetReadDeadline(time.Now().Add(handshakeTimeout)) // nolint: errcheck
-	frame, err := obfuscated2.ExtractFrame(conn)
+	frame, err := obfuscated2.ExtractFrame(socket)
-	conn.SetReadDeadline(time.Time{}) // nolint: errcheck
 	if err != nil {
 		return nil, nil, errors.Annotate(err, "Cannot extract frame")
 	}
-	defer obfuscated2.ReturnFrame(frame)
+	socket.SetReadDeadline(time.Time{}) // nolint: errcheck
 
+	conn := wrappers.NewConn(socket, connID, wrappers.ConnPurposeClient, conf.PublicIPv4, conf.PublicIPv6)
 	obfs2, connOpts, err := obfuscated2.ParseObfuscated2ClientFrame(conf.Secret, frame)
 	if err != nil {
 		return nil, nil, errors.Annotate(err, "Cannot parse obfuscated frame")
 	}
+	connOpts.ConnectionProto = mtproto.ConnectionProtocolAny
+	connOpts.ClientAddr = conn.RemoteAddr()
 
-	socket := wrappers.NewStreamCipherRWC(conn, obfs2.Encryptor, obfs2.Decryptor)
+	conn = wrappers.NewStreamCipher(conn, obfs2.Encryptor, obfs2.Decryptor)
 
-	return connOpts, socket, nil
+	conn.Logger().Infow("Client connection initialized")
+
+	return conn, connOpts, nil
 }

client/middle.go

@@ -0,0 +1,31 @@
+package client
+
+import (
+	"net"
+
+	"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(socket net.Conn, connID string, conf *config.Config) (wrappers.Wrap, *mtproto.ConnectionOpts, error) {
+	conn, opts, err := DirectInit(socket, connID, conf)
+	if err != nil {
+		return nil, nil, err
+	}
+	connStream := conn.(wrappers.StreamReadWriteCloser)
+
+	newConn := wrappers.NewMTProtoAbridged(connStream, opts)
+	if opts.ConnectionType != mtproto.ConnectionTypeAbridged {
+		newConn = wrappers.NewMTProtoIntermediate(connStream, opts)
+	}
+
+	opts.ConnectionProto = mtproto.ConnectionProtocolIPv4
+	if socket.LocalAddr().(*net.TCPAddr).IP.To4() == nil {
+		opts.ConnectionProto = mtproto.ConnectionProtocolIPv6
+	}
+
+	return newConn, opts, err
+}

config/config.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"net"
 	"strconv"
-	"time"
 
 	"github.com/juju/errors"
 )
@@ -14,9 +13,6 @@ import (
 const (
 	BufferWriteSize = 32 * 1024
 	BufferReadSize  = 32 * 1024
-	BufferSizeCopy  = 32 * 1024
-
-	keepAlivePeriod = 20 * time.Second
 )
 
 // Config represents common configuration of mtg.
@@ -35,6 +31,7 @@ type Config struct {
 	StatsIP    net.IP
 
 	Secret []byte
+	AdTag  []byte
 }
 
 // URLs contains links to the proxy (tg://, t.me) and their QR codes.
@@ -56,27 +53,28 @@ func (c *Config) BindAddr() string {
 	return getAddr(c.BindIP, c.BindPort)
 }
 
-// IPv4Addr returns connection string to ipv6 for mtproto proxy.
-func (c *Config) IPv4Addr() string {
-	return getAddr(c.PublicIPv4, c.PublicIPv4Port)
-}
-
-// IPv6Addr returns connection string to ipv6 for mtproto proxy.
-func (c *Config) IPv6Addr() string {
-	return getAddr(c.PublicIPv6, c.PublicIPv6Port)
-}
-
 // StatAddr returns connection string to the stats API.
 func (c *Config) StatAddr() string {
 	return getAddr(c.StatsIP, c.StatsPort)
 }
 
+// UseMiddleProxy defines if this proxy has to connect middle proxies
+// which supports promoted channels or directly access Telegram.
+func (c *Config) UseMiddleProxy() bool {
+	return len(c.AdTag) > 0
+}
+
 // GetURLs returns configured IPURLs instance with links to this server.
 func (c *Config) GetURLs() IPURLs {
-	return IPURLs{
+	urls := IPURLs{}
-		IPv4: getURLs(c.PublicIPv4, c.PublicIPv4Port, c.Secret),
+	if c.PublicIPv4 != nil {
-		IPv6: getURLs(c.PublicIPv6, c.PublicIPv6Port, c.Secret),
+		urls.IPv4 = getURLs(c.PublicIPv4, c.PublicIPv4Port, c.Secret)
 	}
+	if c.PublicIPv6 != nil {
+		urls.IPv6 = getURLs(c.PublicIPv6, c.PublicIPv6Port, c.Secret)
+	}
+
+	return urls
 }
 
 func getAddr(host fmt.Stringer, port uint16) string {
@@ -91,7 +89,7 @@ func NewConfig(debug, verbose bool, // nolint: gocyclo
 	publicIPv4 net.IP, PublicIPv4Port uint16,
 	publicIPv6 net.IP, publicIPv6Port uint16,
 	statsIP net.IP, statsPort uint16,
-	secret string) (*Config, error) {
+	secret, adtag string) (*Config, error) {
 	if len(secret) != 32 {
 		return nil, errors.New("Telegram demands secret of length 32")
 	}
@@ -100,15 +98,22 @@ func NewConfig(debug, verbose bool, // nolint: gocyclo
 		return nil, errors.Annotate(err, "Cannot create config")
 	}
 
+	var adTagBytes []byte
+	if len(adtag) != 0 {
+		adTagBytes, err = hex.DecodeString(adtag)
+		if err != nil {
+			return nil, errors.Annotate(err, "Cannot create config")
+		}
+	}
+
 	if publicIPv4 == nil {
 		publicIPv4, err = getGlobalIPv4()
 		if err != nil {
-			return nil, errors.Errorf("Cannot get public IP")
+			publicIPv4 = nil
-		}
+		} else if publicIPv4.To4() == nil {
-	}
-	if publicIPv4.To4() == nil {
 			return nil, errors.Errorf("IP %s is not IPv4", publicIPv4.String())
 		}
+	}
 	if PublicIPv4Port == 0 {
 		PublicIPv4Port = bindPort
 	}
@@ -116,12 +121,11 @@ func NewConfig(debug, verbose bool, // nolint: gocyclo
 	if publicIPv6 == nil {
 		publicIPv6, err = getGlobalIPv6()
 		if err != nil {
-			publicIPv6 = publicIPv4
+			publicIPv6 = nil
-		}
+		} else if publicIPv6.To4() != nil {
-	}
-	if publicIPv6.To16() == nil {
 			return nil, errors.Errorf("IP %s is not IPv6", publicIPv6.String())
 		}
+	}
 	if publicIPv6Port == 0 {
 		publicIPv6Port = bindPort
 	}
@@ -142,30 +146,8 @@ func NewConfig(debug, verbose bool, // nolint: gocyclo
 		StatsIP:        statsIP,
 		StatsPort:      statsPort,
 		Secret:         secretBytes,
+		AdTag:          adTagBytes,
 	}
 
 	return conf, nil
 }
-
-// SetSocketOptions makes socket keepalive, sets buffer sizes
-func SetSocketOptions(conn net.Conn) error {
-	socket := conn.(*net.TCPConn)
-
-	if err := socket.SetReadBuffer(BufferReadSize); err != nil {
-		return errors.Annotate(err, "Cannot set read buffer size")
-	}
-	if err := socket.SetWriteBuffer(BufferWriteSize); err != nil {
-		return errors.Annotate(err, "Cannot set write buffer size")
-	}
-	if err := socket.SetKeepAlive(true); err != nil {
-		return errors.Annotate(err, "Cannot make socket keepalive")
-	}
-	if err := socket.SetKeepAlivePeriod(keepAlivePeriod); err != nil {
-		return errors.Annotate(err, "Cannot set keepalive period")
-	}
-	if err := socket.SetNoDelay(true); err != nil {
-		return errors.Annotate(err, "Cannot activate nodelay for the socket")
-	}
-
-	return nil
-}

main.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/9seconds/mtg/config"
 	"github.com/9seconds/mtg/proxy"
+	"github.com/9seconds/mtg/stats"
 	"github.com/juju/errors"
 )
 
@@ -70,6 +71,7 @@ var (
 			Uint16()
 
 	secret = app.Arg("secret", "Secret of this proxy.").Required().String()
+	adtag  = app.Arg("adtag", "ADTag of the proxy.").String()
 )
 
 func init() {
@@ -91,7 +93,7 @@ func main() {
 		*publicIPv4, *publicIPv4Port,
 		*publicIPv6, *publicIPv6Port,
 		*statsIP, *statsPort,
-		*secret,
+		*secret, *adtag,
 	)
 	if err != nil {
 		usage(err.Error())
@@ -110,16 +112,23 @@ func main() {
 		zapcore.NewJSONEncoder(encoderCfg),
 		zapcore.Lock(os.Stderr),
 		atom,
-	)).Sugar()
+	))
+	zap.ReplaceGlobals(logger)
+	defer logger.Sync() // nolint: errcheck
 
-	stat := proxy.NewStats(conf)
-	go stat.Serve()
-
-	srv := proxy.NewServer(conf, logger, stat)
 	printURLs(conf.GetURLs())
 
-	if err := srv.Serve(); err != nil {
+	if conf.UseMiddleProxy() {
-		logger.Fatal(err.Error())
+		zap.S().Infow("Use middle proxy connection to Telegram")
+	} else {
+		zap.S().Infow("Use direct connection to Telegram")
+	}
+
+	go stats.Start(conf)
+
+	server := proxy.NewProxy(conf)
+	if err := server.Serve(); err != nil {
+		zap.S().Fatalw("Server stopped", "error", err)
 	}
 }
 

mtproto/connection_options.go

@@ -2,6 +2,7 @@ package mtproto
 
 import (
 	"bytes"
+	"net"
 
 	"github.com/juju/errors"
 )
@@ -10,11 +11,27 @@ import (
 // by the user.
 type ConnectionType uint8
 
+// ConnectionProtocol is a type of IP protocol to use.
+type ConnectionProtocol uint8
+
+// Hacks is a simple structure to store flags for packet transmission.
+type Hacks struct {
+	SimpleAck bool
+	QuickAck  bool
+}
+
 // ConnectionOpts presents an options, metadata on connection requested
 // by the user on handshake.
 type ConnectionOpts struct {
 	DC              int16
 	ConnectionType  ConnectionType
+	ConnectionProto ConnectionProtocol
+	// Read and Write means direction related to the client.
+	// ReadHacks are meant to be flushed on client read
+	// WriteHacks are meant to be flushed on client write.
+	ReadHacks  Hacks
+	WriteHacks Hacks
+	ClientAddr *net.TCPAddr
 }
 
 // Different connection types which user requests from Telegram.
@@ -24,6 +41,14 @@ const (
 	ConnectionTypeIntermediate
 )
 
+// ConnectionProtocol* define which connection protocols to use.
+// ConnectionProtocolAny means that any is suitable.
+const (
+	ConnectionProtocolIPv4 ConnectionProtocol = 1
+	ConnectionProtocolIPv6                    = ConnectionProtocolIPv4 << 1
+	ConnectionProtocolAny                     = ConnectionProtocolIPv4 | ConnectionProtocolIPv6
+)
+
 // Connection tags for mtproto handshakes.
 var (
 	ConnectionTagAbridged     = []byte{0xef, 0xef, 0xef, 0xef}

mtproto/rpc/handshake_request.go

@@ -0,0 +1,26 @@
+package rpc
+
+import "bytes"
+
+// HandshakeRequest is the data type which is responsible for
+// constructing of correct handshake request.
+type HandshakeRequest struct {
+}
+
+// Bytes returns serialized handshake request.
+func (r *HandshakeRequest) Bytes() []byte {
+	buf := &bytes.Buffer{}
+	buf.Grow(len(TagHandshake) + len(HandshakeFlags) + len(HandshakeSenderPID) + len(HandshakePeerPID))
+
+	buf.Write(TagHandshake)
+	buf.Write(HandshakeFlags)
+	buf.Write(HandshakeSenderPID)
+	buf.Write(HandshakePeerPID)
+
+	return buf.Bytes()
+}
+
+// NewHandshakeRequest creates new HandshakeRequest instance.
+func NewHandshakeRequest() *HandshakeRequest {
+	return &HandshakeRequest{}
+}

mtproto/rpc/handshake_response.go

@@ -0,0 +1,55 @@
+package rpc
+
+import (
+	"bytes"
+
+	"github.com/juju/errors"
+)
+
+// HandshakeResponse defines data structure which is used for storage of
+// handshake response.
+type HandshakeResponse struct {
+	Type      []byte
+	Flags     []byte
+	SenderPID []byte
+	PeerPID   []byte
+}
+
+// Bytes returns a serialized handshake response.
+func (r *HandshakeResponse) Bytes() []byte {
+	buf := &bytes.Buffer{}
+
+	buf.Write(r.Type[:])
+	buf.Write(r.Flags[:])
+	buf.Write(r.SenderPID[:])
+	buf.Write(r.PeerPID[:])
+
+	return buf.Bytes()
+}
+
+// Valid checks that handshake response compliments request.
+func (r *HandshakeResponse) Valid(req *HandshakeRequest) error {
+	if !bytes.Equal(r.Type, TagHandshake) {
+		return errors.New("Unexpected handshake tag")
+	}
+	if !bytes.Equal(r.PeerPID, HandshakeSenderPID) {
+		return errors.New("Incorrect sender PID")
+	}
+
+	return nil
+}
+
+// NewHandshakeResponse constructs new handshake response from the given
+// data.
+func NewHandshakeResponse(data []byte) (*HandshakeResponse, error) {
+	if len(data) != 32 {
+		return nil, errors.New("Incorrect handshake response length")
+	}
+
+	return &HandshakeResponse{
+		Type:      data[:4],
+		Flags:     data[4:8],
+		SenderPID: data[8:20],
+		PeerPID:   data[20:],
+	}, nil
+}

mtproto/rpc/nonce_request.go

@@ -0,0 +1,52 @@
+package rpc
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"time"
+
+	"github.com/juju/errors"
+)
+
+// NonceRequest is the data type which contains all the data for correct
+// nonce request.
+type NonceRequest struct {
+	KeySelector []byte
+	CryptoTS    []byte
+	Nonce       []byte
+}
+
+// Bytes returns serialized nonce request.
+func (r *NonceRequest) Bytes() []byte {
+	buf := &bytes.Buffer{}
+
+	buf.Write(TagNonce)
+	buf.Write(r.KeySelector)
+	buf.Write(NonceCryptoAES)
+	buf.Write(r.CryptoTS)
+	buf.Write(r.Nonce)
+
+	return buf.Bytes()
+}
+
+// NewNonceRequest builds new none request based on proxy secret.
+func NewNonceRequest(proxySecret []byte) (*NonceRequest, error) {
+	nonce := make([]byte, 16)
+	keySelector := make([]byte, 4)
+	cryptoTS := make([]byte, 4)
+
+	if _, err := rand.Read(nonce); err != nil {
+		return nil, errors.Annotate(err, "Cannot generate nonce")
+	}
+	copy(keySelector, proxySecret)
+
+	timestamp := time.Now().Truncate(time.Second).Unix() % 4294967296 // 256 ^ 4 - do not know how to name
+	binary.LittleEndian.PutUint32(cryptoTS, uint32(timestamp))
+
+	return &NonceRequest{
+		KeySelector: keySelector,
+		CryptoTS:    cryptoTS,
+		Nonce:       nonce,
+	}, nil
+}

mtproto/rpc/nonce_response.go

@@ -0,0 +1,60 @@
+package rpc
+
+import (
+	"bytes"
+
+	"github.com/juju/errors"
+)
+
+// NonceResponse is the data type which contains data of nonce response.
+type NonceResponse struct {
+	NonceRequest
+
+	Type   []byte
+	Crypto []byte
+}
+
+// Bytes returns serialized form of the nonce response.
+func (r *NonceResponse) Bytes() []byte {
+	buf := &bytes.Buffer{}
+
+	buf.Write(r.Type)
+	buf.Write(r.KeySelector)
+	buf.Write(r.Crypto)
+	buf.Write(r.CryptoTS)
+	buf.Write(r.Nonce)
+
+	return buf.Bytes()
+}
+
+// Valid checks that nonce response compliments nonce request.
+func (r *NonceResponse) Valid(req *NonceRequest) error {
+	if !bytes.Equal(r.Type, TagNonce) {
+		return errors.New("Unexpected RPC type")
+	}
+	if !bytes.Equal(r.Crypto, NonceCryptoAES) {
+		return errors.New("Unexpected crypto type")
+	}
+	if !bytes.Equal(r.KeySelector, req.KeySelector) {
+		return errors.New("Unexpected key selector")
+	}
+
+	return nil
+}
+
+// NewNonceResponse build new nonce response based on the given data.
+func NewNonceResponse(data []byte) (*NonceResponse, error) {
+	if len(data) != 32 {
+		return nil, errors.New("Unexpected message length")
+	}
+
+	return &NonceResponse{
+		NonceRequest: NonceRequest{
+			KeySelector: data[4:8],
+			CryptoTS:    data[12:16],
+			Nonce:       data[16:],
+		},
+		Type:   data[:4],
+		Crypto: data[8:12],
+	}, nil
+}

mtproto/rpc/proxy_flags.go

@@ -0,0 +1,55 @@
+package rpc
+
+import (
+	"encoding/binary"
+	"strings"
+)
+
+type proxyRequestFlags uint32
+
+const (
+	proxyRequestFlagsHasAdTag     proxyRequestFlags = 0x8
+	proxyRequestFlagsEncrypted                      = 0x2
+	proxyRequestFlagsMagic                          = 0x1000
+	proxyRequestFlagsExtMode2                       = 0x20000
+	proxyRequestFlagsIntermediate                   = 0x20000000
+	proxyRequestFlagsAbdridged                      = 0x40000000
+	proxyRequestFlagsQuickAck                       = 0x80000000
+)
+
+var proxyRequestFlagsEncryptedPrefix [8]byte
+
+func (r proxyRequestFlags) Bytes() []byte {
+	converted := make([]byte, 4)
+	binary.LittleEndian.PutUint32(converted, uint32(r))
+
+	return converted
+}
+
+func (r proxyRequestFlags) String() string {
+	flags := make([]string, 0, 7)
+
+	if r&proxyRequestFlagsHasAdTag != 0 {
+		flags = append(flags, "HAS_AD_TAG")
+	}
+	if r&proxyRequestFlagsEncrypted != 0 {
+		flags = append(flags, "ENCRYPTED")
+	}
+	if r&proxyRequestFlagsMagic != 0 {
+		flags = append(flags, "MAGIC")
+	}
+	if r&proxyRequestFlagsExtMode2 != 0 {
+		flags = append(flags, "EXT_MODE_2")
+	}
+	if r&proxyRequestFlagsIntermediate != 0 {
+		flags = append(flags, "INTERMEDIATE")
+	}
+	if r&proxyRequestFlagsAbdridged != 0 {
+		flags = append(flags, "ABRIDGED")
+	}
+	if r&proxyRequestFlagsQuickAck != 0 {
+		flags = append(flags, "QUICK_ACK")
+	}
+
+	return strings.Join(flags, " | ")
+}

mtproto/rpc/proxy_request.go

@@ -0,0 +1,100 @@
+package rpc
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"net"
+
+	"github.com/juju/errors"
+
+	"github.com/9seconds/mtg/mtproto"
+)
+
+// ProxyRequest is the data type for storing data required to compose
+// RPC_PROXY_REQ request.
+type ProxyRequest struct {
+	Flags        proxyRequestFlags
+	ConnectionID []byte
+	OurIPPort    []byte
+	ClientIPPort []byte
+	ADTag        []byte
+	Options      *mtproto.ConnectionOpts
+}
+
+// MakeHeader makes RPC_PROXY_REQ header. We need only to append the
+// data for it.
+func (r *ProxyRequest) MakeHeader(message []byte) (*bytes.Buffer, fmt.Stringer) {
+	bufferLength := len(TagProxyRequest) +
+		4 + // len(flags)
+		len(r.ConnectionID) +
+		len(r.ClientIPPort) +
+		len(r.OurIPPort) +
+		len(ProxyRequestExtraSize) +
+		len(ProxyRequestProxyTag) +
+		1 + // len(AdTag)
+		len(r.ADTag)
+	bufferLength += bufferLength % 4
+
+	buf := &bytes.Buffer{}
+	buf.Grow(bufferLength + len(message))
+
+	flags := r.Flags
+	if r.Options.ReadHacks.QuickAck {
+		flags |= proxyRequestFlagsQuickAck
+	}
+
+	if bytes.HasPrefix(message, proxyRequestFlagsEncryptedPrefix[:]) {
+		flags |= proxyRequestFlagsEncrypted
+	}
+
+	buf.Write(TagProxyRequest)
+	buf.Write(flags.Bytes())
+	buf.Write(r.ConnectionID)
+	buf.Write(r.ClientIPPort)
+	buf.Write(r.OurIPPort)
+	buf.Write(ProxyRequestExtraSize)
+	buf.Write(ProxyRequestProxyTag)
+	buf.WriteByte(byte(len(r.ADTag)))
+	buf.Write(r.ADTag)
+	buf.Write(make([]byte, (4-buf.Len()%4)%4))
+
+	return buf, flags
+}
+
+// NewProxyRequest build new ProxyRequest data structure.
+func NewProxyRequest(clientAddr, ownAddr *net.TCPAddr, opts *mtproto.ConnectionOpts, adTag []byte) (*ProxyRequest, error) {
+	flags := proxyRequestFlagsHasAdTag | proxyRequestFlagsMagic | proxyRequestFlagsExtMode2
+
+	switch opts.ConnectionType {
+	case mtproto.ConnectionTypeAbridged:
+		flags |= proxyRequestFlagsAbdridged
+	case mtproto.ConnectionTypeIntermediate:
+		flags |= proxyRequestFlagsIntermediate
+	}
+
+	request := &ProxyRequest{
+		Flags:        flags,
+		ADTag:        adTag,
+		Options:      opts,
+		ConnectionID: make([]byte, 8),
+		ClientIPPort: make([]byte, 16+4),
+		OurIPPort:    make([]byte, 16+4),
+	}
+
+	if _, err := rand.Read(request.ConnectionID); err != nil {
+		return nil, errors.Annotate(err, "Cannot generate connection ID")
+	}
+
+	port := [4]byte{}
+	copy(request.ClientIPPort[:16], clientAddr.IP.To16())
+	binary.LittleEndian.PutUint32(port[:], uint32(clientAddr.Port))
+	copy(request.ClientIPPort[16:], port[:])
+
+	copy(request.OurIPPort[:16], ownAddr.IP.To16())
+	binary.LittleEndian.PutUint32(port[:], uint32(ownAddr.Port))
+	copy(request.OurIPPort[16:], port[:])
+
+	return request, nil
+}

mtproto/rpc/rpc.go

@@ -0,0 +1,33 @@
+package rpc
+
+// SeqNo* is the number of the sequence which have special meaning for
+// the Telegram.
+const (
+	SeqNoNonce     = -2
+	SeqNoHandshake = -1
+)
+
+// Different constants for RPC protocol
+var (
+	TagCloseExt     = []byte{0xa2, 0x34, 0xb6, 0x5e}
+	TagProxyAns     = []byte{0x0d, 0xda, 0x03, 0x44}
+	TagSimpleAck    = []byte{0x9b, 0x40, 0xac, 0x3b}
+	TagHandshake    = []byte{0xf5, 0xee, 0x82, 0x76}
+	TagNonce        = []byte{0xaa, 0x87, 0xcb, 0x7a}
+	TagProxyRequest = []byte{0xee, 0xf1, 0xce, 0x36}
+
+	NonceCryptoAES = []byte{0x01, 0x00, 0x00, 0x00}
+
+	HandshakeFlags = []byte{0x00, 0x00, 0x00, 0x00}
+
+	ProxyRequestExtraSize = []byte{0x18, 0x00, 0x00, 0x00}
+	ProxyRequestProxyTag  = []byte{0xae, 0x26, 0x1e, 0xdb}
+
+	HandshakeSenderPID []byte
+	HandshakePeerPID   []byte
+)
+
+func init() {
+	HandshakeSenderPID = []byte("IPIPPRPDTIME")
+	HandshakePeerPID = []byte("IPIPPRPDTIME")
+}

obfuscated2/frame.go

@@ -66,57 +66,55 @@ func (f Frame) ConnectionType() (mtproto.ConnectionType, error) {
 
 // Invert inverts frame for extracting encryption keys. Pkease check that link:
 // https://blog.susanka.eu/how-telegram-obfuscates-its-mtproto-traffic/
-func (f Frame) Invert() *Frame {
+func (f Frame) Invert() Frame {
-	reversed := MakeFrame()
+	reversed := make(Frame, FrameLen)
-	copy(*reversed, f)
+	copy(reversed, f)
 
 	for i := 0; i < frameLenKey+frameLenIV; i++ {
-		(*reversed)[frameOffsetFirst+i] = f[frameOffsetIV-1-i]
+		reversed[frameOffsetFirst+i] = f[frameOffsetIV-1-i]
 	}
 
 	return reversed
 }
 
 // ExtractFrame extracts exact obfuscated2 handshake frame from given reader.
-func ExtractFrame(conn io.Reader) (*Frame, error) {
+func ExtractFrame(conn io.Reader) (Frame, error) {
-	frame := MakeFrame()
+	frame := make(Frame, FrameLen)
-	buf := bytes.NewBuffer(*frame)
+	buf := bytes.NewBuffer(frame)
 	buf.Reset()
 
 	if _, err := io.CopyN(buf, conn, FrameLen); err != nil {
-		ReturnFrame(frame)
 		return nil, errors.Annotate(err, "Cannot extract obfuscated header")
 	}
-	copy(*frame, buf.Bytes())
+	copy(frame, buf.Bytes())
 
 	return frame, nil
 }
 
-func generateFrame(connectionType mtproto.ConnectionType) *Frame {
+func generateFrame(connectionType mtproto.ConnectionType) Frame {
-	frame := MakeFrame()
+	frame := make(Frame, FrameLen)
-	data := *frame
 
 	for {
-		if _, err := rand.Read(data); err != nil {
+		if _, err := rand.Read(frame); err != nil {
 			continue
 		}
-		if data[0] == 0xef {
+		if frame[0] == 0xef {
 			continue
 		}
 
-		val := (uint32(data[3]) << 24) | (uint32(data[2]) << 16) | (uint32(data[1]) << 8) | uint32(data[0])
+		val := (uint32(frame[3]) << 24) | (uint32(frame[2]) << 16) | (uint32(frame[1]) << 8) | uint32(frame[0])
 		if val == 0x44414548 || val == 0x54534f50 || val == 0x20544547 || val == 0x4954504f || val == 0xeeeeeeee {
 			continue
 		}
 
-		val = (uint32(data[7]) << 24) | (uint32(data[6]) << 16) | (uint32(data[5]) << 8) | uint32(data[4])
+		val = (uint32(frame[7]) << 24) | (uint32(frame[6]) << 16) | (uint32(frame[5]) << 8) | uint32(frame[4])
 		if val == 0x00000000 {
 			continue
 		}
 
 		// error has to be checked before calling this function
 		tag, _ := connectionType.Tag() // nolint: errcheck
-		copy(data.Magic(), tag)
+		copy(frame.Magic(), tag)
 
 		return frame
 	}

obfuscated2/frame_pool.go

@@ -1,24 +0,0 @@
-package obfuscated2
-
-import "sync"
-
-var framePool sync.Pool
-
-// MakeFrame returns new pointer to the handshake frame.
-func MakeFrame() *Frame {
-	return framePool.Get().(*Frame)
-}
-
-// ReturnFrame returns pointer to the handshake frame back to the pool.
-func ReturnFrame(f *Frame) {
-	framePool.Put(f)
-}
-
-func init() {
-	framePool = sync.Pool{
-		New: func() interface{} {
-			data := make(Frame, FrameLen)
-			return &data
-		},
-	}
-}

obfuscated2/frame_test.go

@@ -54,21 +54,21 @@ func TestFrameValid(t *testing.T) {
 
 func TestFrameDoubleInvert(t *testing.T) {
 	frame := makeFrame()
-	assert.True(t, bytes.Equal(frame, *frame.Invert().Invert()))
+	assert.True(t, bytes.Equal(frame, frame.Invert().Invert()))
 }
 
 func TestFrameInvert(t *testing.T) {
 	frame := makeFrame()
 	reversed := frame.Invert()
 
-	assert.Exactly(t, frame[:8], (*reversed)[:8])
+	assert.Exactly(t, frame[:8], reversed[:8])
-	assert.Exactly(t, frame[56:], (*reversed)[56:])
+	assert.Exactly(t, frame[56:], reversed[56:])
 
 	toCompare := make([]byte, 48)
 	for i := 0; i < 48; i++ {
 		toCompare[i] = frame[55-i]
 	}
-	assert.Equal(t, []byte((*reversed)[8:56]), toCompare)
+	assert.Equal(t, []byte(reversed[8:56]), toCompare)
 }
 
 func TestFrameGenerateValid(t *testing.T) {

obfuscated2/obfuscated2.go

@@ -21,7 +21,7 @@ type Obfuscated2 struct {
 // details: http://telegra.ph/telegram-blocks-wtf-05-26
 //
 // Beware, link above is in russian.
-func ParseObfuscated2ClientFrame(secret []byte, frame *Frame) (*Obfuscated2, *mtproto.ConnectionOpts, error) {
+func ParseObfuscated2ClientFrame(secret []byte, frame Frame) (*Obfuscated2, *mtproto.ConnectionOpts, error) {
 	decHasher := sha256.New()
 	decHasher.Write(frame.Key()) // nolint: errcheck
 	decHasher.Write(secret)      // nolint: errcheck
@@ -33,9 +33,8 @@ func ParseObfuscated2ClientFrame(secret []byte, frame *Frame) (*Obfuscated2, *mt
 	encHasher.Write(secret)              // nolint: errcheck
 	encryptor := makeStreamCipher(encHasher.Sum(nil), invertedFrame.IV())
 
-	decryptedFrame := MakeFrame()
+	decryptedFrame := make(Frame, FrameLen)
-	defer ReturnFrame(decryptedFrame)
+	decryptor.XORKeyStream(decryptedFrame, frame)
-	decryptor.XORKeyStream(*decryptedFrame, *frame)
 	connType, err := decryptedFrame.ConnectionType()
 	if err != nil {
 		return nil, nil, errors.Annotate(err, "Unknown protocol")
@@ -56,18 +55,17 @@ func ParseObfuscated2ClientFrame(secret []byte, frame *Frame) (*Obfuscated2, *mt
 // MakeTelegramObfuscated2Frame creates new handshake frame to send to
 // Telegram.
 // https://blog.susanka.eu/how-telegram-obfuscates-its-mtproto-traffic/
-func MakeTelegramObfuscated2Frame(opts *mtproto.ConnectionOpts) (*Obfuscated2, *Frame) {
+func MakeTelegramObfuscated2Frame(opts *mtproto.ConnectionOpts) (*Obfuscated2, Frame) {
 	frame := generateFrame(opts.ConnectionType)
 
 	encryptor := makeStreamCipher(frame.Key(), frame.IV())
 	decryptorFrame := frame.Invert()
 	decryptor := makeStreamCipher(decryptorFrame.Key(), decryptorFrame.IV())
 
-	copyFrame := MakeFrame()
+	copyFrame := make(Frame, FrameLen)
-	defer ReturnFrame(copyFrame)
+	copy(copyFrame[:frameOffsetIV], frame[:frameOffsetIV])
-	copy((*copyFrame)[:frameOffsetIV], (*frame)[:frameOffsetIV])
+	encryptor.XORKeyStream(frame, frame)
-	encryptor.XORKeyStream(*frame, *frame)
+	copy(frame[:frameOffsetIV], copyFrame[:frameOffsetIV])
-	copy((*frame)[:frameOffsetIV], (*copyFrame)[:frameOffsetIV])
 
 	obfs := &Obfuscated2{
 		Decryptor: decryptor,

obfuscated2/obfuscated2_test.go

@@ -18,7 +18,7 @@ func TestObfs2TelegramFrameDecrypt(t *testing.T) {
 	decryptor := makeStreamCipher(frame.Key(), frame.IV())
 
 	decrypted := make(Frame, FrameLen)
-	decryptor.XORKeyStream(decrypted, *frame)
+	decryptor.XORKeyStream(decrypted, frame)
 
 	_, err := decrypted.ConnectionType()
 	assert.Nil(t, err)
@@ -53,8 +53,8 @@ func TestObfs2Full(t *testing.T) {
 
 	encryptor := makeStreamCipher(clientKey, clientFrame.IV())
 	encrypted := make(Frame, FrameLen)
-	encryptor.XORKeyStream(encrypted, *clientFrame)
+	encryptor.XORKeyStream(encrypted, clientFrame)
-	copy(encrypted[:56], (*clientFrame)[:56])
+	copy(encrypted[:56], clientFrame[:56])
 
 	invertedClientFrame := clientFrame.Invert()
 	clientHasher = sha256.New()
@@ -63,7 +63,7 @@ func TestObfs2Full(t *testing.T) {
 	invertedClientKey := clientHasher.Sum(nil)
 	clientDecryptor := makeStreamCipher(invertedClientKey, invertedClientFrame.IV())
 
-	clientObfs, _, err := ParseObfuscated2ClientFrame(secret, &encrypted)
+	clientObfs, _, err := ParseObfuscated2ClientFrame(secret, encrypted)
 	assert.Nil(t, err)
 
 	connOpts := &mtproto.ConnectionOpts{
@@ -73,7 +73,7 @@ func TestObfs2Full(t *testing.T) {
 	tgObfs, tgFrame := MakeTelegramObfuscated2Frame(connOpts)
 	tgDecryptor := makeStreamCipher(tgFrame.Key(), tgFrame.IV())
 	decrypted := make(Frame, FrameLen)
-	tgDecryptor.XORKeyStream(decrypted, *tgFrame)
+	tgDecryptor.XORKeyStream(decrypted, tgFrame)
 	_, err = decrypted.ConnectionType()
 	assert.Nil(t, err)
 

proxy/copy_pool.go

@@ -1,18 +0,0 @@
-package proxy
-
-import (
-	"sync"
-
-	"github.com/9seconds/mtg/config"
-)
-
-var copyPool sync.Pool
-
-func init() {
-	copyPool = sync.Pool{
-		New: func() interface{} {
-			data := make([]byte, config.BufferSizeCopy)
-			return &data
-		},
-	}
-}

proxy/proxy.go

@@ -0,0 +1,162 @@
+package proxy
+
+import (
+	"io"
+	"net"
+	"sync"
+
+	"github.com/juju/errors"
+	uuid "github.com/satori/go.uuid"
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/client"
+	"github.com/9seconds/mtg/config"
+	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/stats"
+	"github.com/9seconds/mtg/telegram"
+	"github.com/9seconds/mtg/wrappers"
+)
+
+// Proxy is a core of this program.
+type Proxy struct {
+	clientInit client.Init
+	tg         telegram.Telegram
+	conf       *config.Config
+}
+
+// Serve runs TCP proxy server.
+func (p *Proxy) Serve() error {
+	lsock, err := net.Listen("tcp", p.conf.BindAddr())
+	if err != nil {
+		return errors.Annotate(err, "Cannot create listen socket")
+	}
+
+	for {
+		if conn, err := lsock.Accept(); err != nil {
+			zap.S().Errorw("Cannot allocate incoming connection", "error", err)
+		} else {
+			go p.accept(conn)
+		}
+	}
+}
+
+func (p *Proxy) accept(conn net.Conn) {
+	connID := uuid.NewV4().String()
+	log := zap.S().With("connection_id", connID).Named("main")
+
+	defer func() {
+		conn.Close() // nolint: errcheck
+
+		if err := recover(); err != nil {
+			stats.NewCrash()
+			log.Errorw("Crash of accept handler", "error", err)
+		}
+	}()
+
+	log.Infow("Client connected", "addr", conn.RemoteAddr())
+
+	clientConn, opts, err := p.clientInit(conn, connID, p.conf)
+	if err != nil {
+		log.Errorw("Cannot initialize client connection", "error", err)
+		return
+	}
+	defer clientConn.(io.Closer).Close() // nolint: errcheck
+
+	stats.ClientConnected(opts.ConnectionType, clientConn.RemoteAddr())
+	defer stats.ClientDisconnected(opts.ConnectionType, clientConn.RemoteAddr())
+
+	serverConn, err := p.getTelegramConn(opts, connID)
+	if err != nil {
+		log.Errorw("Cannot initialize server connection", "error", err)
+		return
+	}
+	defer serverConn.(io.Closer).Close() // nolint: errcheck
+
+	wait := &sync.WaitGroup{}
+	wait.Add(2)
+
+	if p.conf.UseMiddleProxy() {
+		clientPacket := clientConn.(wrappers.PacketReadWriteCloser)
+		serverPacket := serverConn.(wrappers.PacketReadWriteCloser)
+		go p.middlePipe(clientPacket, serverPacket, wait, &opts.ReadHacks)
+		go p.middlePipe(serverPacket, clientPacket, wait, &opts.WriteHacks)
+	} else {
+		clientStream := clientConn.(wrappers.StreamReadWriteCloser)
+		serverStream := serverConn.(wrappers.StreamReadWriteCloser)
+		go p.directPipe(clientStream, serverStream, wait)
+		go p.directPipe(serverStream, clientStream, wait)
+	}
+
+	wait.Wait()
+
+	log.Infow("Client disconnected", "addr", conn.RemoteAddr())
+}
+
+func (p *Proxy) getTelegramConn(opts *mtproto.ConnectionOpts, connID string) (wrappers.Wrap, error) {
+	streamConn, err := p.tg.Dial(connID, opts)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot dial to Telegram")
+	}
+
+	packetConn, err := p.tg.Init(opts, streamConn)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot handshake telegram")
+	}
+
+	return packetConn, nil
+}
+
+func (p *Proxy) middlePipe(src wrappers.PacketReadCloser, dst io.WriteCloser, wait *sync.WaitGroup, hacks *mtproto.Hacks) {
+	defer func() {
+		src.Close() // nolint: errcheck
+		dst.Close() // nolint: errcheck
+		wait.Done()
+	}()
+
+	for {
+		hacks.SimpleAck = false
+		hacks.QuickAck = false
+
+		packet, err := src.Read()
+		if err != nil {
+			src.Logger().Warnw("Cannot read packet", "error", err)
+			return
+		}
+		if _, err = dst.Write(packet); err != nil {
+			src.Logger().Warnw("Cannot write packet", "error", err)
+			return
+		}
+	}
+}
+
+func (p *Proxy) directPipe(src wrappers.StreamReadCloser, dst io.WriteCloser, wait *sync.WaitGroup) {
+	defer func() {
+		src.Close() // nolint: errcheck
+		dst.Close() // nolint: errcheck
+		wait.Done()
+	}()
+
+	if _, err := io.Copy(dst, src); err != nil {
+		src.Logger().Warnw("Cannot pump sockets", "error", err)
+	}
+}
+
+// NewProxy returns new proxy instance.
+func NewProxy(conf *config.Config) *Proxy {
+	var clientInit client.Init
+	var tg telegram.Telegram
+
+	if conf.UseMiddleProxy() {
+		clientInit = client.MiddleInit
+		tg = telegram.NewMiddleTelegram(conf)
+	} else {
+		clientInit = client.DirectInit
+		tg = telegram.NewDirectTelegram(conf)
+	}
+
+	return &Proxy{
+		conf:       conf,
+		clientInit: clientInit,
+		tg:         tg,
+	}
+}

proxy/server.go

@@ -1,149 +0,0 @@
-package proxy
-
-import (
-	"context"
-	"io"
-	"net"
-	"sync"
-
-	"github.com/juju/errors"
-	uuid "github.com/satori/go.uuid"
-	"go.uber.org/zap"
-
-	"github.com/9seconds/mtg/client"
-	"github.com/9seconds/mtg/config"
-	"github.com/9seconds/mtg/mtproto"
-	"github.com/9seconds/mtg/telegram"
-	"github.com/9seconds/mtg/wrappers"
-)
-
-// Server is an insgtance of MTPROTO proxy.
-type Server struct {
-	conf       *config.Config
-	logger     *zap.SugaredLogger
-	stats      *Stats
-	tg         telegram.Telegram
-	clientInit client.Init
-}
-
-// Serve does MTPROTO proxying.
-func (s *Server) Serve() error {
-	lsock, err := net.Listen("tcp", s.conf.BindAddr())
-	if err != nil {
-		return errors.Annotate(err, "Cannot create listen socket")
-	}
-
-	for {
-		if conn, err := lsock.Accept(); err != nil {
-			s.logger.Warn("Cannot allocate incoming connection", "error", err)
-		} else {
-			go s.accept(conn)
-		}
-	}
-}
-
-func (s *Server) accept(conn net.Conn) {
-	defer func() {
-		s.stats.closeConnection()
-		conn.Close() // nolint: errcheck
-
-		if r := recover(); r != nil {
-			s.logger.Errorw("Crash of accept handler", "error", r)
-		}
-	}()
-
-	s.stats.newConnection()
-	ctx, cancel := context.WithCancel(context.Background())
-	socketID := uuid.NewV4().String()
-
-	s.logger.Debugw("Client connected",
-		"addr", conn.RemoteAddr().String(),
-		"socketid", socketID,
-	)
-
-	connOpts, clientConn, err := s.getClientStream(ctx, cancel, conn, socketID)
-	if err != nil {
-		s.logger.Warnw("Cannot initialize client connection",
-			"addr", conn.RemoteAddr().String(),
-			"socketid", socketID,
-			"error", err,
-		)
-		return
-	}
-	defer clientConn.Close() // nolint: errcheck
-
-	tgConn, err := s.getTelegramStream(ctx, cancel, connOpts, socketID)
-	if err != nil {
-		s.logger.Warnw("Cannot initialize Telegram connection",
-			"socketid", socketID,
-			"error", err,
-		)
-		return
-	}
-	defer tgConn.Close() // nolint: errcheck
-
-	wait := &sync.WaitGroup{}
-	wait.Add(2)
-
-	go s.pipe(clientConn, tgConn, wait)
-	go s.pipe(tgConn, clientConn, wait)
-
-	<-ctx.Done()
-	wait.Wait()
-
-	s.logger.Debugw("Client disconnected",
-		"addr", conn.RemoteAddr().String(),
-		"socketid", socketID,
-	)
-}
-
-func (s *Server) getClientStream(ctx context.Context, cancel context.CancelFunc, conn net.Conn, socketID string) (*mtproto.ConnectionOpts, io.ReadWriteCloser, error) {
-	connOpts, socket, err := s.clientInit(conn, s.conf)
-	if err != nil {
-		return nil, nil, errors.Annotate(err, "Cannot init client connection")
-	}
-
-	socket = wrappers.NewTrafficRWC(socket, s.stats.addIncomingTraffic, s.stats.addOutgoingTraffic)
-	socket = wrappers.NewLogRWC(socket, s.logger, socketID, "client")
-	socket = wrappers.NewCtxRWC(ctx, cancel, socket)
-
-	return connOpts, socket, nil
-}
-
-func (s *Server) getTelegramStream(ctx context.Context, cancel context.CancelFunc, connOpts *mtproto.ConnectionOpts, socketID string) (io.ReadWriteCloser, error) {
-	conn, err := s.tg.Dial(connOpts)
-	if err != nil {
-		return nil, errors.Annotate(err, "Cannot connect to Telegram")
-	}
-
-	conn = wrappers.NewTrafficRWC(conn, s.stats.addIncomingTraffic, s.stats.addOutgoingTraffic)
-	conn, err = s.tg.Init(connOpts, conn)
-	if err != nil {
-		return nil, errors.Annotate(err, "Cannot handshake Telegram")
-	}
-
-	conn = wrappers.NewLogRWC(conn, s.logger, socketID, "telegram")
-	conn = wrappers.NewCtxRWC(ctx, cancel, conn)
-
-	return conn, nil
-}
-
-func (s *Server) pipe(dst io.Writer, src io.Reader, wait *sync.WaitGroup) {
-	defer wait.Done()
-
-	buf := copyPool.Get().(*[]byte)
-	defer copyPool.Put(buf)
-
-	io.CopyBuffer(dst, src, *buf) // nolint: errcheck
-}
-
-// NewServer creates new instance of MTPROTO proxy.
-func NewServer(conf *config.Config, logger *zap.SugaredLogger, stat *Stats) *Server {
-	return &Server{
-		conf:       conf,
-		logger:     logger,
-		stats:      stat,
-		tg:         telegram.NewDirectTelegram(conf),
-		clientInit: client.DirectInit,
-	}
-}

proxy/stats.go

@@ -1,74 +0,0 @@
-package proxy
-
-import (
-	"encoding/json"
-	"net/http"
-	"strconv"
-	"sync/atomic"
-	"time"
-
-	"github.com/9seconds/mtg/config"
-)
-
-type statsUptime time.Time
-
-func (s statsUptime) MarshalJSON() ([]byte, error) {
-	uptime := int(time.Since(time.Time(s)).Seconds())
-	return []byte(strconv.Itoa(uptime)), nil
-}
-
-// Stats is a datastructure for statistics on work of this proxy.
-type Stats struct {
-	AllConnections    uint64 `json:"all_connections"`
-	ActiveConnections uint32 `json:"active_connections"`
-	Traffic           struct {
-		Incoming uint64 `json:"incoming"`
-		Outgoing uint64 `json:"outgoing"`
-	} `json:"traffic"`
-	URLs   config.IPURLs `json:"urls"`
-	Uptime statsUptime   `json:"uptime"`
-
-	conf *config.Config
-}
-
-func (s *Stats) newConnection() {
-	atomic.AddUint64(&s.AllConnections, 1)
-	atomic.AddUint32(&s.ActiveConnections, 1)
-}
-
-func (s *Stats) closeConnection() {
-	atomic.AddUint32(&s.ActiveConnections, ^uint32(0))
-}
-
-func (s *Stats) addIncomingTraffic(n int) {
-	atomic.AddUint64(&s.Traffic.Incoming, uint64(n))
-}
-
-func (s *Stats) addOutgoingTraffic(n int) {
-	atomic.AddUint64(&s.Traffic.Outgoing, uint64(n))
-}
-
-// Serve runs statistics HTTP server.
-func (s *Stats) Serve() {
-	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/json")
-
-		encoder := json.NewEncoder(w)
-		encoder.SetEscapeHTML(false)
-		encoder.SetIndent("", "  ")
-		encoder.Encode(s) // nolint: errcheck, gas
-	})
-
-	http.ListenAndServe(s.conf.StatAddr(), nil) // nolint: errcheck, gas
-}
-
-// NewStats returns new instance of statistics datastructure.
-func NewStats(conf *config.Config) *Stats {
-	stat := &Stats{
-		Uptime: statsUptime(time.Now()),
-		conf:   conf,
-	}
-	stat.URLs = conf.GetURLs()
-
-	return stat
-}

run-mtg.sh

@@ -21,7 +21,6 @@ docker run \
     --sysctl net.ipv4.tcp_congestion_control=bbr \
     --sysctl net.ipv4.tcp_fastopen=3 \
     --sysctl net.ipv4.tcp_fin_timeout=30 \
-    --sysctl net.ipv4.tcp_keepalive_time=1200 \
     --sysctl net.ipv4.tcp_max_syn_backlog=4096 \
     --sysctl net.ipv4.tcp_max_tw_buckets=5000 \
     --sysctl net.ipv4.tcp_mtu_probing=1 \

stats/channels.go

@@ -0,0 +1,151 @@
+package stats
+
+import (
+	"net"
+	"time"
+
+	"github.com/9seconds/mtg/mtproto"
+)
+
+const (
+	crashesChanLength     = 1
+	connectionsChanLength = 20
+	trafficChanLength     = 5000
+)
+
+var (
+	crashesChan     = make(chan struct{}, crashesChanLength)
+	connectionsChan = make(chan *connectionData, connectionsChanLength)
+	trafficChan     = make(chan *trafficData, trafficChanLength)
+)
+
+type connectionData struct {
+	connectionType mtproto.ConnectionType
+	connected      bool
+	addr           *net.TCPAddr
+}
+
+type trafficData struct {
+	traffic int
+	ingress bool
+}
+
+func crashManager() {
+	for range crashesChan {
+		instance.mutex.RLock()
+
+		instance.Crashes++
+
+		instance.mutex.RUnlock()
+	}
+}
+
+func connectionManager() { // nolint: gocyclo
+	for event := range connectionsChan {
+		instance.mutex.RLock()
+
+		isIPv4 := event.addr.IP.To4() != nil
+		var inc uint32 = 1
+		if !event.connected {
+			inc = ^uint32(0)
+		}
+
+		switch event.connectionType {
+		case mtproto.ConnectionTypeAbridged:
+			if isIPv4 {
+				instance.ActiveConnections.Abridged.IPv4 += inc
+				if event.connected {
+					instance.AllConnections.Abridged.IPv4 += inc
+				}
+			} else {
+				instance.ActiveConnections.Abridged.IPv6 += inc
+				if event.connected {
+					instance.AllConnections.Abridged.IPv6 += inc
+				}
+			}
+		default:
+			if isIPv4 {
+				instance.ActiveConnections.Intermediate.IPv4 += inc
+				if event.connected {
+					instance.AllConnections.Intermediate.IPv4 += inc
+				}
+			} else {
+				instance.ActiveConnections.Intermediate.IPv6 += inc
+				if event.connected {
+					instance.AllConnections.Intermediate.IPv6 += inc
+				}
+			}
+		}
+
+		instance.mutex.RUnlock()
+	}
+}
+
+func trafficManager() {
+	speedChan := time.Tick(time.Second)
+
+	for {
+		select {
+		case event := <-trafficChan:
+			instance.mutex.RLock()
+
+			if event.ingress {
+				instance.Traffic.Ingress += trafficValue(event.traffic)
+				instance.speedCurrent.Ingress += trafficSpeedValue(event.traffic)
+			} else {
+				instance.Traffic.Egress += trafficValue(event.traffic)
+				instance.speedCurrent.Egress += trafficSpeedValue(event.traffic)
+			}
+
+			instance.mutex.RUnlock()
+		case <-speedChan:
+			instance.mutex.RLock()
+
+			instance.Speed.Ingress = instance.speedCurrent.Ingress
+			instance.Speed.Egress = instance.speedCurrent.Egress
+			instance.speedCurrent.Ingress = trafficSpeedValue(0)
+			instance.speedCurrent.Egress = trafficSpeedValue(0)
+
+			instance.mutex.RUnlock()
+		}
+	}
+}
+
+// NewCrash indicates new crash.
+func NewCrash() {
+	crashesChan <- struct{}{}
+}
+
+// ClientConnected indicates that new client was connected.
+func ClientConnected(connectionType mtproto.ConnectionType, addr *net.TCPAddr) {
+	connectionsChan <- &connectionData{
+		connectionType: connectionType,
+		addr:           addr,
+		connected:      true,
+	}
+}
+
+// ClientDisconnected indicates that client was disconnected.
+func ClientDisconnected(connectionType mtproto.ConnectionType, addr *net.TCPAddr) {
+	connectionsChan <- &connectionData{
+		connectionType: connectionType,
+		addr:           addr,
+		connected:      false,
+	}
+}
+
+// IngressTraffic accounts new ingress traffic.
+func IngressTraffic(traffic int) {
+	trafficChan <- &trafficData{
+		traffic: traffic,
+		ingress: true,
+	}
+}
+
+// EgressTraffic accounts new ingress traffic.
+func EgressTraffic(traffic int) {
+	trafficChan <- &trafficData{
+		traffic: traffic,
+		ingress: false,
+	}
+}

stats/server.go

@@ -0,0 +1,57 @@
+package stats
+
+import (
+	"encoding/json"
+	"net/http"
+	"sync"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/config"
+)
+
+var instance *stats
+
+// Start starts new statisitcs server.
+func Start(conf *config.Config) {
+	log := zap.S().Named("stats")
+
+	instance = &stats{
+		URLs:   conf.GetURLs(),
+		Uptime: uptime(time.Now()),
+		mutex:  &sync.RWMutex{},
+	}
+
+	go crashManager()
+	go connectionManager()
+	go trafficManager()
+
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+
+		instance.mutex.Lock()
+		first, err := json.Marshal(instance)
+		instance.mutex.Unlock()
+
+		if err != nil {
+			log.Errorw("Cannot encode json", "error", err)
+			http.Error(w, "Internal server error", 500)
+			return
+		}
+
+		interm := map[string]interface{}{}
+		json.Unmarshal(first, &interm) // nolint: errcheck
+
+		encoder := json.NewEncoder(w)
+		encoder.SetEscapeHTML(false)
+		encoder.SetIndent("", "  ")
+		if err = encoder.Encode(interm); err != nil {
+			log.Errorw("Cannot encode json", "error", err)
+		}
+	})
+
+	if err := http.ListenAndServe(conf.StatAddr(), nil); err != nil {
+		log.Fatalw("Stats server has been stopped", "error", err)
+	}
+}

stats/stats.go

@@ -0,0 +1,100 @@
+package stats
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"sync"
+	"time"
+
+	humanize "github.com/dustin/go-humanize"
+
+	"github.com/9seconds/mtg/config"
+)
+
+type uptime time.Time
+
+func (u uptime) MarshalJSON() ([]byte, error) {
+	duration := time.Since(time.Time(u))
+	value := map[string]string{
+		"seconds": strconv.Itoa(int(duration.Seconds())),
+		"human":   humanize.Time(time.Time(u)),
+	}
+
+	return json.Marshal(value)
+}
+
+type trafficValue uint64
+
+func (t trafficValue) MarshalJSON() ([]byte, error) {
+	tv := uint64(t)
+	value := map[string]interface{}{
+		"bytes": tv,
+		"human": humanize.Bytes(tv),
+	}
+
+	return json.Marshal(value)
+}
+
+type trafficSpeedValue uint64
+
+func (t trafficSpeedValue) MarshalJSON() ([]byte, error) {
+	speed := uint64(t)
+	value := map[string]interface{}{
+		"bytes/s": speed,
+		"human":   fmt.Sprintf("%s/S", humanize.Bytes(speed)),
+	}
+
+	return json.Marshal(value)
+}
+
+type connections struct {
+	All          connectionType `json:"all"`
+	Abridged     connectionType `json:"abridged"`
+	Intermediate connectionType `json:"intermediate"`
+}
+
+func (c connections) MarshalJSON() ([]byte, error) {
+	c.All.IPv4 = c.Abridged.IPv4 + c.Intermediate.IPv4
+	c.All.IPv6 = c.Abridged.IPv6 + c.Intermediate.IPv6
+
+	value := struct {
+		All          connectionType `json:"all"`
+		Abridged     connectionType `json:"abridged"`
+		Intermediate connectionType `json:"intermediate"`
+	}{
+		All:          c.All,
+		Abridged:     c.Abridged,
+		Intermediate: c.Intermediate,
+	}
+
+	return json.Marshal(value)
+}
+
+type connectionType struct {
+	IPv6 uint32 `json:"ipv6"`
+	IPv4 uint32 `json:"ipv4"`
+}
+
+type traffic struct {
+	Ingress trafficValue `json:"ingress"`
+	Egress  trafficValue `json:"egress"`
+}
+
+type speed struct {
+	Ingress trafficSpeedValue `json:"ingress"`
+	Egress  trafficSpeedValue `json:"egress"`
+}
+
+type stats struct {
+	URLs              config.IPURLs `json:"urls"`
+	ActiveConnections connections   `json:"active_connections"`
+	AllConnections    connections   `json:"all_connections"`
+	Traffic           traffic       `json:"traffic"`
+	Speed             speed         `json:"speed"`
+	Uptime            uptime        `json:"uptime"`
+	Crashes           uint32        `json:"crashes"`
+
+	speedCurrent speed
+	mutex        *sync.RWMutex
+}

telegram/dialer.go

@@ -1,21 +1,25 @@
 package telegram
 
 import (
-	"io"
 	"net"
 	"time"
 
 	"github.com/juju/errors"
 
 	"github.com/9seconds/mtg/config"
+	"github.com/9seconds/mtg/wrappers"
 )
 
 const (
 	telegramDialTimeout = 10 * time.Second
+	readBufferSize      = 64 * 1024
+	writeBufferSize     = 64 * 1024
 )
 
 type tgDialer struct {
 	net.Dialer
+
+	conf *config.Config
 }
 
 func (t *tgDialer) dial(addr string) (net.Conn, error) {
@@ -23,18 +27,27 @@ func (t *tgDialer) dial(addr string) (net.Conn, error) {
 	if err != nil {
 		return nil, errors.Annotate(err, "Cannot connect to Telegram")
 	}
-	if err = config.SetSocketOptions(conn); err != nil {
+
-		return nil, errors.Annotate(err, "Cannot set socket options")
+	tcpSocket := conn.(*net.TCPConn)
+	if err = tcpSocket.SetNoDelay(true); err != nil {
+		return nil, errors.Annotate(err, "Cannot set NO_DELAY to Telegram")
+	}
+	if err = tcpSocket.SetReadBuffer(readBufferSize); err != nil {
+		return nil, errors.Annotate(err, "Cannot set read buffer size on telegram socket")
+	}
+	if err = tcpSocket.SetWriteBuffer(writeBufferSize); err != nil {
+		return nil, errors.Annotate(err, "Cannot set write buffer size on telegram socket")
 	}
 
 	return conn, nil
 }
 
-func (t *tgDialer) dialRWC(addr string) (io.ReadWriteCloser, error) {
+func (t *tgDialer) dialRWC(addr, connID string) (wrappers.StreamReadWriteCloser, error) {
 	conn, err := t.dial(addr)
 	if err != nil {
 		return nil, err
 	}
+	tgConn := wrappers.NewConn(conn, connID, wrappers.ConnPurposeTelegram, t.conf.PublicIPv4, t.conf.PublicIPv6)
 
-	return conn, nil
+	return tgConn, nil
 }

telegram/direct.go

@@ -1,7 +1,6 @@
 package telegram
 
 import (
-	"io"
 	"net"
 
 	"github.com/juju/errors"
@@ -33,7 +32,7 @@ type directTelegram struct {
 	baseTelegram
 }
 
-func (t *directTelegram) Dial(connOpts *mtproto.ConnectionOpts) (io.ReadWriteCloser, error) {
+func (t *directTelegram) Dial(connID string, connOpts *mtproto.ConnectionOpts) (wrappers.StreamReadWriteCloser, error) {
 	dc := connOpts.DC
 	if dc < 0 {
 		dc = -dc
@@ -41,25 +40,27 @@ func (t *directTelegram) Dial(connOpts *mtproto.ConnectionOpts) (io.ReadWriteClo
 		dc = 1
 	}
 
-	return t.baseTelegram.dial(dc - 1)
+	return t.baseTelegram.dial(dc-1, connID, connOpts.ConnectionProto)
 }
 
-func (t *directTelegram) Init(connOpts *mtproto.ConnectionOpts, conn io.ReadWriteCloser) (io.ReadWriteCloser, error) {
+func (t *directTelegram) Init(connOpts *mtproto.ConnectionOpts, conn wrappers.StreamReadWriteCloser) (wrappers.Wrap, error) {
 	obfs2, frame := obfuscated2.MakeTelegramObfuscated2Frame(connOpts)
-	defer obfuscated2.ReturnFrame(frame)
 
-	if n, err := conn.Write(*frame); err != nil || n != len(*frame) {
+	if _, err := conn.Write(frame); err != nil {
 		return nil, errors.Annotate(err, "Cannot write hadnshake frame")
 	}
 
-	return wrappers.NewStreamCipherRWC(conn, obfs2.Encryptor, obfs2.Decryptor), nil
+	return wrappers.NewStreamCipher(conn, obfs2.Encryptor, obfs2.Decryptor), nil
 }
 
 // NewDirectTelegram returns Telegram instance which connects directly
 // to Telegram bypassing middleproxies.
 func NewDirectTelegram(conf *config.Config) Telegram {
 	return &directTelegram{baseTelegram{
-		dialer:      tgDialer{net.Dialer{Timeout: telegramDialTimeout}},
+		dialer: tgDialer{
+			Dialer: net.Dialer{Timeout: telegramDialTimeout},
+			conf:   conf,
+		},
 		v4Addresses: directV4Addresses,
 		v6Addresses: directV6Addresses,
 	}}

telegram/middle.go

@@ -0,0 +1,136 @@
+package telegram
+
+import (
+	"io"
+	"net"
+	"net/http"
+	"sync"
+
+	"github.com/juju/errors"
+
+	"github.com/9seconds/mtg/config"
+	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/mtproto/rpc"
+	"github.com/9seconds/mtg/wrappers"
+)
+
+type middleTelegram struct {
+	middleTelegramCaller
+
+	conf *config.Config
+}
+
+func (t *middleTelegram) Init(connOpts *mtproto.ConnectionOpts, conn wrappers.StreamReadWriteCloser) (wrappers.Wrap, error) {
+	rpcNonceConn := wrappers.NewMTProtoFrame(conn, rpc.SeqNoNonce)
+
+	rpcNonceReq, err := t.sendRPCNonceRequest(rpcNonceConn)
+	if err != nil {
+		return nil, err
+	}
+	rpcNonceResp, err := t.receiveRPCNonceResponse(rpcNonceConn, rpcNonceReq)
+	if err != nil {
+		return nil, err
+	}
+
+	secureConn := wrappers.NewMiddleProxyCipher(conn, rpcNonceReq, rpcNonceResp, t.proxySecret)
+	frameConn := wrappers.NewMTProtoFrame(secureConn, rpc.SeqNoHandshake)
+
+	rpcHandshakeReq, err := t.sendRPCHandshakeRequest(frameConn)
+	if err != nil {
+		return nil, err
+	}
+	_, err = t.receiveRPCHandshakeResponse(frameConn, rpcHandshakeReq)
+	if err != nil {
+		return nil, err
+	}
+
+	proxyConn, err := wrappers.NewMTProtoProxy(frameConn, connOpts, t.conf.AdTag)
+	if err != nil {
+		return nil, err
+	}
+	proxyConn.Logger().Infow("Telegram connection initialized")
+
+	return proxyConn, nil
+}
+
+func (t *middleTelegram) sendRPCNonceRequest(conn io.Writer) (*rpc.NonceRequest, error) {
+	rpcNonceReq, err := rpc.NewNonceRequest(t.proxySecret)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot create RPC nonce request")
+	}
+	if _, err = conn.Write(rpcNonceReq.Bytes()); err != nil {
+		return nil, errors.Annotate(err, "Cannot send RPC nonce request")
+	}
+
+	return rpcNonceReq, nil
+}
+
+func (t *middleTelegram) receiveRPCNonceResponse(conn wrappers.PacketReader, req *rpc.NonceRequest) (*rpc.NonceResponse, error) {
+	packet, err := conn.Read()
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot read RPC nonce response")
+	}
+
+	rpcNonceResp, err := rpc.NewNonceResponse(packet)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot initialize RPC nonce response")
+	}
+	if err = rpcNonceResp.Valid(req); err != nil {
+		return nil, errors.Annotate(err, "Invalid RPC nonce response")
+	}
+
+	return rpcNonceResp, nil
+}
+
+func (t *middleTelegram) sendRPCHandshakeRequest(conn io.Writer) (*rpc.HandshakeRequest, error) {
+	req := rpc.NewHandshakeRequest()
+	if _, err := conn.Write(req.Bytes()); err != nil {
+		return nil, errors.Annotate(err, "Cannot send RPC handshake request")
+	}
+
+	return req, nil
+}
+
+func (t *middleTelegram) receiveRPCHandshakeResponse(conn wrappers.PacketReader, req *rpc.HandshakeRequest) (*rpc.HandshakeResponse, error) {
+	packet, err := conn.Read()
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot read RPC handshake response")
+	}
+
+	rpcHandshakeResp, err := rpc.NewHandshakeResponse(packet)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot initialize RPC handshake response")
+	}
+	if err = rpcHandshakeResp.Valid(req); err != nil {
+		return nil, errors.Annotate(err, "Invalid RPC handshake response")
+	}
+
+	return rpcHandshakeResp, nil
+}
+
+// NewMiddleTelegram creates new instance of Telegram which works with
+// middle proxies.
+func NewMiddleTelegram(conf *config.Config) Telegram {
+	tg := &middleTelegram{
+		middleTelegramCaller: middleTelegramCaller{
+			baseTelegram: baseTelegram{
+				dialer: tgDialer{
+					Dialer: net.Dialer{Timeout: telegramDialTimeout},
+					conf:   conf,
+				},
+			},
+			httpClient: &http.Client{
+				Timeout: middleTelegramHTTPClientTimeout,
+			},
+			dialerMutex: &sync.RWMutex{},
+		},
+		conf: conf,
+	}
+
+	if err := tg.update(); err != nil {
+		panic(err)
+	}
+	go tg.autoUpdate()
+
+	return tg
+}

telegram/middle_caller.go

@@ -0,0 +1,152 @@
+package telegram
+
+import (
+	"bufio"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/wrappers"
+)
+
+const (
+	middleTelegramAutoUpdateInterval = 6 * time.Hour
+	middleTelegramHTTPClientTimeout  = 30 * time.Second
+
+	tgAddrProxySecret = "https://core.telegram.org/getProxySecret"   // nolint: gas
+	tgAddrProxyV4     = "https://core.telegram.org/getProxyConfig"   // nolint: gas
+	tgAddrProxyV6     = "https://core.telegram.org/getProxyConfigV6" // nolint: gas
+	tgUserAgent       = "mtg"
+)
+
+var middleTelegramProxyConfigSplitter = regexp.MustCompile(`\s+`)
+
+type middleTelegramCaller struct {
+	baseTelegram
+
+	proxySecret []byte
+	dialerMutex *sync.RWMutex
+	httpClient  *http.Client
+}
+
+func (t *middleTelegramCaller) Dial(connID string, connOpts *mtproto.ConnectionOpts) (wrappers.StreamReadWriteCloser, error) {
+	dc := connOpts.DC
+	if dc == 0 {
+		dc = 1
+	}
+	t.dialerMutex.RLock()
+	defer t.dialerMutex.RUnlock()
+
+	return t.baseTelegram.dial(dc, connID, connOpts.ConnectionProto)
+}
+
+func (t *middleTelegramCaller) autoUpdate() {
+	for range time.Tick(middleTelegramAutoUpdateInterval) {
+		if err := t.update(); err != nil {
+			zap.S().Warnw("Cannot update from Telegram", "error", err)
+		}
+	}
+}
+
+func (t *middleTelegramCaller) update() error {
+	secret, err := t.getTelegramProxySecret()
+	if err != nil {
+		return errors.Annotate(err, "Cannot get proxy secret")
+	}
+
+	v4Addresses, err := t.getTelegramAddresses(tgAddrProxyV4)
+	if err != nil {
+		return errors.Annotate(err, "Cannot get ipv4 addresses")
+	}
+
+	v6Addresses, err := t.getTelegramAddresses(tgAddrProxyV6)
+	if err != nil {
+		return errors.Annotate(err, "Cannot get ipv6 addresses")
+	}
+
+	t.dialerMutex.Lock()
+	t.proxySecret = secret
+	t.v4Addresses = v4Addresses
+	t.v6Addresses = v6Addresses
+	t.dialerMutex.Unlock()
+
+	zap.S().Infow("Telegram middle proxy data has been updated")
+
+	return nil
+}
+
+func (t *middleTelegramCaller) getTelegramProxySecret() ([]byte, error) {
+	resp, err := t.call(tgAddrProxySecret)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot access telegram server")
+	}
+	defer resp.Body.Close() // nolint: errcheck
+
+	secret, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot read response")
+	}
+
+	return secret, nil
+}
+
+func (t *middleTelegramCaller) getTelegramAddresses(url string) (map[int16][]string, error) {
+	resp, err := t.call(url)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot access telegram server")
+	}
+	defer resp.Body.Close() // nolint: errcheck
+
+	scanner := bufio.NewScanner(resp.Body)
+	data := map[int16][]string{}
+	for scanner.Scan() {
+		text := strings.TrimSpace(scanner.Text())
+		if strings.HasPrefix(text, "#") {
+			continue
+		}
+
+		chunks := middleTelegramProxyConfigSplitter.Split(text, 3)
+		if len(chunks) != 3 || chunks[0] != "proxy_for" {
+			return nil, errors.Errorf("Incorrect config '%s'", text)
+		}
+		dcIdx64, err2 := strconv.ParseInt(chunks[1], 10, 16)
+		if err2 != nil {
+			return nil, errors.Errorf("Incorrect config '%s'", text)
+		}
+		dcIdx := int16(dcIdx64)
+
+		addr := strings.TrimRight(chunks[2], ";")
+		if _, _, err2 = net.SplitHostPort(addr); err != nil {
+			return nil, errors.Annotatef(err2, "Incorrect config '%s'", text)
+		}
+
+		if addresses, ok := data[dcIdx]; ok {
+			data[dcIdx] = append(addresses, addr)
+		} else {
+			data[dcIdx] = []string{addr}
+		}
+	}
+	err = scanner.Err()
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot read response from the telegram")
+	}
+
+	return data, nil
+}
+
+func (t *middleTelegramCaller) call(url string) (*http.Response, error) {
+	req, _ := http.NewRequest("GET", url, nil)
+	req.Header.Set("Accept", "text/plain")
+	req.Header.Set("User-Agent", tgUserAgent)
+
+	return t.httpClient.Do(req)
+}

telegram/telegram.go

@@ -1,20 +1,18 @@
 package telegram
 
 import (
-	"io"
 	"math/rand"
 
 	"github.com/juju/errors"
 
 	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/wrappers"
 )
 
-// Telegram defines an interface to connect to Telegram. This
+// Telegram is an interface for different Telegram work modes.
-// encapsulates logic of working with middleproxies or direct
-// connections.
 type Telegram interface {
-	Dial(*mtproto.ConnectionOpts) (io.ReadWriteCloser, error)
+	Dial(string, *mtproto.ConnectionOpts) (wrappers.StreamReadWriteCloser, error)
-	Init(*mtproto.ConnectionOpts, io.ReadWriteCloser) (io.ReadWriteCloser, error)
+	Init(*mtproto.ConnectionOpts, wrappers.StreamReadWriteCloser) (wrappers.Wrap, error)
 }
 
 type baseTelegram struct {
@@ -24,17 +22,22 @@ type baseTelegram struct {
 	v6Addresses map[int16][]string
 }
 
-func (b *baseTelegram) dial(dcIdx int16) (io.ReadWriteCloser, error) {
+func (b *baseTelegram) dial(dcIdx int16, connID string, proto mtproto.ConnectionProtocol) (wrappers.StreamReadWriteCloser, error) {
 	addrs := make([]string, 2)
+
+	if proto&mtproto.ConnectionProtocolIPv6 != 0 {
 		if addr, ok := b.v6Addresses[dcIdx]; ok && len(addr) > 0 {
 			addrs = append(addrs, addr[rand.Intn(len(addr))])
 		}
+	}
+	if proto&mtproto.ConnectionProtocolIPv4 != 0 {
 		if addr, ok := b.v4Addresses[dcIdx]; ok && len(addr) > 0 {
 			addrs = append(addrs, addr[rand.Intn(len(addr))])
 		}
+	}
 
 	for _, addr := range addrs {
-		if conn, err := b.dialer.dialRWC(addr); err == nil {
+		if conn, err := b.dialer.dialRWC(addr, connID); err == nil {
 			return conn, err
 		}
 	}

utils/read_current_data.go

@@ -0,0 +1,21 @@
+package utils
+
+import "io"
+
+const readCurrentDataBufferSize = 1024 + 1 // + 1 because telegram operates with blocks mod 4
+
+// ReadCurrentData reads all data from io.Reader which is ready to be read.
+func ReadCurrentData(src io.Reader) (rv []byte, err error) {
+	buf := make([]byte, readCurrentDataBufferSize)
+	n := readCurrentDataBufferSize
+
+	for n == len(buf) {
+		n, err = src.Read(buf)
+		if err != nil {
+			return nil, err
+		}
+		rv = append(rv, buf[:n]...)
+	}
+
+	return rv, nil
+}

utils/reverse_bytes.go

@@ -0,0 +1,15 @@
+package utils
+
+// ReverseBytes is a common slice reverser.
+func ReverseBytes(data []byte) []byte {
+	dataLen := len(data)
+	rv := make([]byte, dataLen)
+
+	rv[dataLen/2] = data[dataLen/2]
+	for i := dataLen/2 - 1; i >= 0; i-- {
+		opp := dataLen - i - 1
+		rv[i], rv[opp] = data[opp], data[i]
+	}
+
+	return rv
+}

utils/uint24.go

@@ -0,0 +1,15 @@
+package utils
+
+// Uint24 is a replacement for the absent Go uint24 data type.
+// This data type is little endian.
+type Uint24 [3]byte
+
+// ToUint24 converts number to Uint24.
+func ToUint24(number uint32) Uint24 {
+	return Uint24{byte(number), byte(number >> 8), byte(number >> 16)}
+}
+
+// FromUint24 converts Uint24 to number.
+func FromUint24(number Uint24) uint32 {
+	return uint32(number[0]) + (uint32(number[1]) << 8) + (uint32(number[2]) << 16)
+}

wrappers/blockcipher.go

@@ -0,0 +1,99 @@
+package wrappers
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"net"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/utils"
+	"github.com/juju/errors"
+)
+
+// BlockCipher is a stream writer which encrypts/decrypts blocks of data
+// with AES CBC. This also is buffered reader. It means, that block
+// reading is transparent for it, you can assume you are working with
+// good old io.Reader.
+type BlockCipher struct {
+	buf *bytes.Buffer
+
+	logger    *zap.SugaredLogger
+	conn      StreamReadWriteCloser
+	encryptor cipher.BlockMode
+	decryptor cipher.BlockMode
+}
+
+func (b *BlockCipher) Read(p []byte) (int, error) {
+	if b.buf.Len() > 0 {
+		return b.flush(p)
+	}
+
+	buf := []byte{}
+	for len(buf) == 0 || len(buf)%aes.BlockSize != 0 {
+		rv, err := utils.ReadCurrentData(b.conn)
+		if err != nil {
+			return 0, errors.Annotate(err, "Cannot read from socket")
+		}
+		buf = append(buf, rv...)
+	}
+
+	b.decryptor.CryptBlocks(buf, buf)
+	b.buf.Write(buf)
+
+	return b.flush(p)
+}
+
+func (b *BlockCipher) flush(p []byte) (int, error) {
+	if b.buf.Len() <= len(p) {
+		sizeToReturn := b.buf.Len()
+		copy(p, b.buf.Bytes())
+		b.buf.Reset()
+		return sizeToReturn, nil
+	}
+
+	return b.buf.Read(p)
+}
+
+func (b *BlockCipher) Write(p []byte) (int, error) {
+	if len(p)%aes.BlockSize > 0 {
+		return 0, errors.Errorf("Incorrect block size %d", len(p))
+	}
+
+	encrypted := make([]byte, len(p))
+	b.encryptor.CryptBlocks(encrypted, p)
+
+	return b.conn.Write(encrypted)
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (b *BlockCipher) Logger() *zap.SugaredLogger {
+	return b.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (b *BlockCipher) LocalAddr() *net.TCPAddr {
+	return b.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (b *BlockCipher) RemoteAddr() *net.TCPAddr {
+	return b.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn.
+func (b *BlockCipher) Close() error {
+	return b.conn.Close()
+}
+
+// NewBlockCipher creates new instance of BlockCipher based on given data.
+func NewBlockCipher(conn StreamReadWriteCloser, encryptor, decryptor cipher.BlockMode) StreamReadWriteCloser {
+	return &BlockCipher{
+		buf:       &bytes.Buffer{},
+		conn:      conn,
+		logger:    conn.Logger().Named("block-cipher"),
+		encryptor: encryptor,
+		decryptor: decryptor,
+	}
+}

wrappers/buffer_pool.go

@@ -1,27 +0,0 @@
-package wrappers
-
-import (
-	"bytes"
-	"sync"
-)
-
-var bufPool sync.Pool
-
-func getBuffer() *bytes.Buffer {
-	buf := bufPool.Get().(*bytes.Buffer)
-	buf.Reset()
-
-	return buf
-}
-
-func putBuffer(buf *bytes.Buffer) {
-	bufPool.Put(buf)
-}
-
-func init() {
-	bufPool = sync.Pool{
-		New: func() interface{} {
-			return &bytes.Buffer{}
-		},
-	}
-}

wrappers/conn.go

@@ -0,0 +1,121 @@
+package wrappers
+
+import (
+	"net"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/stats"
+)
+
+// ConnPurpose is intented to be identifier of connection purpose. We
+// sometimes want to treat client/telegram connection differently (for
+// logging for example).
+type ConnPurpose uint8
+
+func (c ConnPurpose) String() string {
+	switch c {
+	case ConnPurposeClient:
+		return "client"
+	case ConnPurposeTelegram:
+		return "telegram"
+	}
+
+	return ""
+}
+
+// ConnPurpose* define different connection types.
+const (
+	ConnPurposeClient = iota
+	ConnPurposeTelegram
+)
+
+const (
+	connTimeoutRead  = 2 * time.Minute
+	connTimeoutWrite = 2 * time.Minute
+)
+
+// Conn is a basic wrapper for net.Conn providing the most low-level
+// logic and management as possible.
+type Conn struct {
+	connID string
+	conn   net.Conn
+	logger *zap.SugaredLogger
+
+	publicIPv4 net.IP
+	publicIPv6 net.IP
+}
+
+func (c *Conn) Write(p []byte) (int, error) {
+	c.conn.SetWriteDeadline(time.Now().Add(connTimeoutWrite)) // nolint: errcheck
+	n, err := c.conn.Write(p)
+
+	c.logger.Debugw("Write to stream", "bytes", n, "error", err)
+	stats.EgressTraffic(n)
+
+	return n, err
+}
+
+func (c *Conn) Read(p []byte) (int, error) {
+	c.conn.SetReadDeadline(time.Now().Add(connTimeoutRead)) // nolint: errcheck
+	n, err := c.conn.Read(p)
+
+	c.logger.Debugw("Read from stream", "bytes", n, "error", err)
+	stats.IngressTraffic(n)
+
+	return n, err
+}
+
+// Close closes underlying net.Conn instance.
+func (c *Conn) Close() error {
+	defer c.logger.Debugw("Close connection")
+	return c.conn.Close()
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (c *Conn) Logger() *zap.SugaredLogger {
+	return c.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (c *Conn) LocalAddr() *net.TCPAddr {
+	addr := c.conn.LocalAddr().(*net.TCPAddr)
+	newAddr := *addr
+
+	if c.RemoteAddr().IP.To4() != nil {
+		if c.publicIPv4 != nil {
+			newAddr.IP = c.publicIPv4
+		}
+	} else if c.publicIPv6 != nil {
+		newAddr.IP = c.publicIPv6
+	}
+
+	return &newAddr
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (c *Conn) RemoteAddr() *net.TCPAddr {
+	return c.conn.RemoteAddr().(*net.TCPAddr)
+}
+
+// NewConn initializes Conn wrapper for net.Conn.
+func NewConn(conn net.Conn, connID string, purpose ConnPurpose, publicIPv4, publicIPv6 net.IP) StreamReadWriteCloser {
+	logger := zap.S().With(
+		"connection_id", connID,
+		"local_address", conn.LocalAddr(),
+		"remote_address", conn.RemoteAddr(),
+		"purpose", purpose,
+	).Named("conn")
+
+	wrapper := Conn{
+		logger:     logger,
+		connID:     connID,
+		conn:       conn,
+		publicIPv4: publicIPv4,
+		publicIPv6: publicIPv6,
+	}
+	wrapper.logger = logger.With("faked_local_addr", wrapper.LocalAddr())
+
+	return &wrapper
+}

wrappers/ctxrwc.go

@@ -1,59 +0,0 @@
-package wrappers
-
-import (
-	"context"
-	"io"
-
-	"github.com/juju/errors"
-)
-
-// CtxReadWriteCloser wraps underlying connection and does management of the
-// context and its cancel function.
-type CtxReadWriteCloser struct {
-	ctx    context.Context
-	conn   io.ReadWriteCloser
-	cancel context.CancelFunc
-}
-
-// Read reads from connection
-func (c *CtxReadWriteCloser) Read(p []byte) (int, error) {
-	select {
-	case <-c.ctx.Done():
-		return 0, errors.Annotate(c.ctx.Err(), "Read is failed because of closed context")
-	default:
-		n, err := c.conn.Read(p)
-		if err != nil {
-			c.cancel()
-		}
-		return n, err
-	}
-}
-
-// Write writes into connection.
-func (c *CtxReadWriteCloser) Write(p []byte) (int, error) {
-	select {
-	case <-c.ctx.Done():
-		return 0, errors.Annotate(c.ctx.Err(), "Write is failed because of closed context")
-	default:
-		n, err := c.conn.Write(p)
-		if err != nil {
-			c.cancel()
-		}
-		return n, err
-	}
-}
-
-// Close closes underlying connection.
-func (c *CtxReadWriteCloser) Close() error {
-	return c.conn.Close()
-}
-
-// NewCtxRWC returns ReadWriteCloser which respects given context,
-// cancellation etc.
-func NewCtxRWC(ctx context.Context, cancel context.CancelFunc, conn io.ReadWriteCloser) io.ReadWriteCloser {
-	return &CtxReadWriteCloser{
-		conn:   conn,
-		ctx:    ctx,
-		cancel: cancel,
-	}
-}

wrappers/logrwc.go

@@ -1,47 +0,0 @@
-package wrappers
-
-import (
-	"io"
-
-	"go.uber.org/zap"
-)
-
-// LogReadWriteCloser adds additional logging for reading/writing. All
-// logging is performed for debug mode only.
-type LogReadWriteCloser struct {
-	conn   io.ReadWriteCloser
-	logger *zap.SugaredLogger
-	sockid string
-	name   string
-}
-
-// Read reads from connection
-func (l *LogReadWriteCloser) Read(p []byte) (n int, err error) {
-	n, err = l.conn.Read(p)
-	l.logger.Debugw("Finish reading", "name", l.name, "socketid", l.sockid, "nbytes", n, "error", err)
-	return
-}
-
-// Write writes into connection.
-func (l *LogReadWriteCloser) Write(p []byte) (n int, err error) {
-	n, err = l.conn.Write(p)
-	l.logger.Debugw("Finish writing", "name", l.name, "socketid", l.sockid, "nbytes", n, "error", err)
-	return
-}
-
-// Close closes underlying connection.
-func (l *LogReadWriteCloser) Close() error {
-	err := l.conn.Close()
-	l.logger.Debugw("Finish closing socket", "name", l.name, "socketid", l.sockid, "error", err)
-	return err
-}
-
-// NewLogRWC wraps ReadWriteCloser with logger calls.
-func NewLogRWC(conn io.ReadWriteCloser, logger *zap.SugaredLogger, sockid string, name string) io.ReadWriteCloser {
-	return &LogReadWriteCloser{
-		conn:   conn,
-		logger: logger,
-		sockid: sockid,
-		name:   name,
-	}
-}

wrappers/mtproto_abridged.go

@@ -0,0 +1,159 @@
+package wrappers
+
+import (
+	"bytes"
+	"io"
+	"net"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/utils"
+)
+
+const (
+	mtprotoAbridgedSmallPacketLength = 0x7f
+	mtprotoAbridgedQuickAckLength    = 0x80
+	mtprotoAbridgedLargePacketLength = 16777216 // 256 ^ 3
+)
+
+// MTProtoAbridged presents abridged connection between client and
+// middle proxy.
+type MTProtoAbridged struct {
+	conn   StreamReadWriteCloser
+	opts   *mtproto.ConnectionOpts
+	logger *zap.SugaredLogger
+
+	readCounter  uint32
+	writeCounter uint32
+}
+
+func (m *MTProtoAbridged) Read() ([]byte, error) {
+	defer func() {
+		m.readCounter++
+	}()
+
+	m.logger.Debugw("Read packet",
+		"simple_ack", m.opts.ReadHacks.SimpleAck,
+		"quick_ack", m.opts.ReadHacks.QuickAck,
+		"counter", m.readCounter,
+	)
+
+	buf := &bytes.Buffer{}
+	buf.Grow(3)
+
+	if _, err := io.CopyN(buf, m.conn, 1); err != nil {
+		return nil, errors.Annotate(err, "Cannot read message length")
+	}
+	msgLength := uint32(buf.Bytes()[0])
+	buf.Reset()
+
+	m.logger.Debugw("Packet first byte",
+		"byte", msgLength,
+		"counter", m.readCounter,
+		"simple_ack", m.opts.ReadHacks.SimpleAck,
+		"quick_ack", m.opts.ReadHacks.QuickAck,
+	)
+
+	if msgLength >= mtprotoAbridgedQuickAckLength {
+		m.opts.ReadHacks.QuickAck = true
+		msgLength -= mtprotoAbridgedQuickAckLength
+	}
+
+	if msgLength == mtprotoAbridgedSmallPacketLength {
+		if _, err := io.CopyN(buf, m.conn, 3); err != nil {
+			return nil, errors.Annotate(err, "Cannot read the correct message length")
+		}
+		number := utils.Uint24{}
+		copy(number[:], buf.Bytes())
+		msgLength = utils.FromUint24(number)
+	}
+	msgLength *= 4
+
+	m.logger.Debugw("Packet length",
+		"length", msgLength,
+		"simple_ack", m.opts.ReadHacks.SimpleAck,
+		"quick_ack", m.opts.ReadHacks.QuickAck,
+		"counter", m.readCounter,
+	)
+
+	buf.Reset()
+	buf.Grow(int(msgLength))
+	if _, err := io.CopyN(buf, m.conn, int64(msgLength)); err != nil {
+		return nil, errors.Annotate(err, "Cannot read message")
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (m *MTProtoAbridged) Write(p []byte) (int, error) {
+	defer func() {
+		m.writeCounter++
+	}()
+
+	m.logger.Debugw("Write packet",
+		"length", len(p),
+		"simple_ack", m.opts.WriteHacks.SimpleAck,
+		"quick_ack", m.opts.WriteHacks.QuickAck,
+		"counter", m.writeCounter,
+	)
+
+	if len(p)%4 != 0 {
+		return 0, errors.Errorf("Incorrect packet length %d", len(p))
+	}
+
+	if m.opts.WriteHacks.SimpleAck {
+		return m.conn.Write(utils.ReverseBytes(p))
+	}
+
+	packetLength := len(p) / 4
+	switch {
+	case packetLength < mtprotoAbridgedSmallPacketLength:
+		newData := append([]byte{byte(packetLength)}, p...)
+		return m.conn.Write(newData)
+
+	case packetLength < mtprotoAbridgedLargePacketLength:
+		length24 := utils.ToUint24(uint32(packetLength))
+
+		buf := &bytes.Buffer{}
+		buf.Grow(1 + 3 + len(p))
+
+		buf.WriteByte(byte(mtprotoAbridgedSmallPacketLength))
+		buf.Write(length24[:])
+		buf.Write(p)
+
+		return m.conn.Write(buf.Bytes())
+	}
+
+	return 0, errors.Errorf("Packet is too big %d", len(p))
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (m *MTProtoAbridged) Logger() *zap.SugaredLogger {
+	return m.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (m *MTProtoAbridged) LocalAddr() *net.TCPAddr {
+	return m.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (m *MTProtoAbridged) RemoteAddr() *net.TCPAddr {
+	return m.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn instance.
+func (m *MTProtoAbridged) Close() error {
+	return m.conn.Close()
+}
+
+// NewMTProtoAbridged creates new wrapper for abridged client connection.
+func NewMTProtoAbridged(conn StreamReadWriteCloser, opts *mtproto.ConnectionOpts) PacketReadWriteCloser {
+	return &MTProtoAbridged{
+		conn:   conn,
+		opts:   opts,
+		logger: conn.Logger().Named("mtproto-abridged"),
+	}
+}

wrappers/mtproto_cipher.go

@@ -0,0 +1,96 @@
+package wrappers
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/md5" // nolint: gas
+	"crypto/sha1"
+	"encoding/binary"
+	"net"
+
+	"github.com/9seconds/mtg/mtproto/rpc"
+	"github.com/9seconds/mtg/utils"
+)
+
+type cipherPurpose uint8
+
+const (
+	cipherPurposeClient cipherPurpose = iota
+	cipherPurposeServer
+)
+
+var emptyIP = [4]byte{0x00, 0x00, 0x00, 0x00}
+
+// NewMiddleProxyCipher creates new block cipher to proxy<->telegram
+// connection.
+func NewMiddleProxyCipher(conn StreamReadWriteCloser, req *rpc.NonceRequest, resp *rpc.NonceResponse, secret []byte) StreamReadWriteCloser {
+	localAddr := conn.LocalAddr()
+	remoteAddr := conn.RemoteAddr()
+
+	encKey, encIV := deriveKeys(cipherPurposeClient, req, resp, localAddr, remoteAddr, secret)
+	decKey, decIV := deriveKeys(cipherPurposeServer, req, resp, localAddr, remoteAddr, secret)
+
+	enc, _ := makeEncrypterDecrypter(encKey, encIV)
+	_, dec := makeEncrypterDecrypter(decKey, decIV)
+
+	return NewBlockCipher(conn, enc, dec)
+}
+
+func deriveKeys(purpose cipherPurpose, req *rpc.NonceRequest, resp *rpc.NonceResponse, client *net.TCPAddr, remote *net.TCPAddr, secret []byte) ([]byte, []byte) {
+	message := bytes.Buffer{}
+	message.Write(resp.Nonce[:])
+	message.Write(req.Nonce[:])
+	message.Write(req.CryptoTS[:])
+
+	clientIPv4 := emptyIP[:]
+	serverIPv4 := emptyIP[:]
+	if client.IP.To4() != nil {
+		clientIPv4 = utils.ReverseBytes(client.IP.To4())
+		serverIPv4 = utils.ReverseBytes(remote.IP.To4())
+	}
+	message.Write(serverIPv4)
+
+	var port [2]byte
+	binary.LittleEndian.PutUint16(port[:], uint16(client.Port))
+	message.Write(port[:])
+
+	switch purpose {
+	case cipherPurposeClient:
+		message.WriteString("CLIENT")
+	case cipherPurposeServer:
+		message.WriteString("SERVER")
+	default:
+		panic("Unexpected cipher purpose")
+	}
+
+	message.Write(clientIPv4)
+	binary.LittleEndian.PutUint16(port[:], uint16(remote.Port))
+	message.Write(port[:])
+	message.Write(secret)
+	message.Write(resp.Nonce[:])
+
+	if client.IP.To4() == nil {
+		message.Write(client.IP.To16())
+		message.Write(remote.IP.To16())
+	}
+	message.Write(req.Nonce[:])
+
+	data := message.Bytes()
+	md5sum := md5.Sum(data[1:]) // nolint: gas
+	sha1sum := sha1.Sum(data)
+
+	key := append(md5sum[:12], sha1sum[:]...)
+	iv := md5.Sum(data[2:]) // nolint: gas
+
+	return key, iv[:]
+}
+
+func makeEncrypterDecrypter(key, iv []byte) (cipher.BlockMode, cipher.BlockMode) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		panic(err)
+	}
+
+	return cipher.NewCBCEncrypter(block, iv), cipher.NewCBCDecrypter(block, iv)
+}

wrappers/mtproto_frame.go

@@ -0,0 +1,160 @@
+package wrappers
+
+import (
+	"bytes"
+	"crypto/aes"
+	"encoding/binary"
+	"hash/crc32"
+	"io"
+	"io/ioutil"
+	"net"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+)
+
+const (
+	mtprotoFrameMinMessageLength = 12
+	mtprotoFrameMaxMessageLength = 16777216
+)
+
+var mtprotoFramePadding = []byte{0x04, 0x00, 0x00, 0x00}
+
+// MTProtoFrame is a wrapper which converts written data to the MTProtoFrame.
+// The format of the frame:
+//
+// [ MSGLEN(4) | SEQNO(4) | MSG(...) | CRC32(4) | PADDING(4*x) ]
+//
+// MSGLEN is the length of the message + len of seqno and msglen.
+// SEQNO is the number of frame in the receive/send sequence. If client
+//   sends a message with SeqNo 18, it has to receive message with SeqNo 18.
+// MSG is the data which has to be written
+// CRC32 is the CRC32 checksum of MSGLEN + SEQNO + MSG
+// PADDING is custom padding schema to complete frame length to such that
+//    len(frame) % 16 == 0
+type MTProtoFrame struct {
+	conn   StreamReadWriteCloser
+	logger *zap.SugaredLogger
+
+	readSeqNo  int32
+	writeSeqNo int32
+}
+
+func (m *MTProtoFrame) Read() ([]byte, error) { // nolint: gocyclo
+	buf := &bytes.Buffer{}
+	sum := crc32.NewIEEE()
+	writer := io.MultiWriter(buf, sum)
+
+	for {
+		buf.Reset()
+		sum.Reset()
+		if _, err := io.CopyN(writer, m.conn, 4); err != nil {
+			return nil, errors.Annotate(err, "Cannot read frame padding")
+		}
+		if !bytes.Equal(buf.Bytes(), mtprotoFramePadding) {
+			break
+		}
+	}
+
+	messageLength := binary.LittleEndian.Uint32(buf.Bytes())
+	m.logger.Debugw("Read MTProto frame",
+		"messageLength", messageLength,
+		"sequence_number", m.readSeqNo,
+	)
+	if messageLength%4 != 0 || messageLength < mtprotoFrameMinMessageLength || messageLength > mtprotoFrameMaxMessageLength {
+		return nil, errors.Errorf("Incorrect frame message length %d", messageLength)
+	}
+
+	buf.Reset()
+	buf.Grow(int(messageLength) - 4 - 4)
+	if _, err := io.CopyN(writer, m.conn, int64(messageLength)-4-4); err != nil {
+		return nil, errors.Annotate(err, "Cannot read the message frame")
+	}
+
+	var seqNo int32
+	binary.Read(buf, binary.LittleEndian, &seqNo) // nolint: errcheck
+	if seqNo != m.readSeqNo {
+		return nil, errors.Errorf("Unexpected sequence number %d (wait for %d)", seqNo, m.readSeqNo)
+	}
+
+	data, _ := ioutil.ReadAll(buf)
+	buf.Reset()
+	// write to buf, not to writer. This is because we are going to fetch
+	// crc32 checksum.
+	if _, err := io.CopyN(buf, m.conn, 4); err != nil {
+		return nil, errors.Annotate(err, "Cannot read checksum")
+	}
+
+	checksum := binary.LittleEndian.Uint32(buf.Bytes())
+	if checksum != sum.Sum32() {
+		return nil, errors.Errorf("CRC32 checksum mismatch. Wait for %d, got %d", sum.Sum32(), checksum)
+	}
+
+	m.logger.Debugw("Read MTProto frame",
+		"messageLength", messageLength,
+		"sequence_number", m.readSeqNo,
+		"dataLength", len(data),
+		"checksum", checksum,
+	)
+	m.readSeqNo++
+
+	return data, nil
+}
+
+func (m *MTProtoFrame) Write(p []byte) (int, error) {
+	messageLength := 4 + 4 + len(p) + 4
+	paddingLength := (aes.BlockSize - messageLength%aes.BlockSize) % aes.BlockSize
+
+	buf := &bytes.Buffer{}
+	buf.Grow(messageLength + paddingLength)
+
+	binary.Write(buf, binary.LittleEndian, uint32(messageLength)) // nolint: errcheck
+	binary.Write(buf, binary.LittleEndian, m.writeSeqNo)          // nolint: errcheck
+	buf.Write(p)
+
+	checksum := crc32.ChecksumIEEE(buf.Bytes())
+	binary.Write(buf, binary.LittleEndian, checksum) // nolint: errcheck
+	buf.Write(bytes.Repeat(mtprotoFramePadding, paddingLength/4))
+
+	m.logger.Debugw("Write MTProto frame",
+		"length", len(p),
+		"sequence_number", m.writeSeqNo,
+		"crc32", checksum,
+		"frame_length", buf.Len(),
+	)
+	m.writeSeqNo++
+
+	_, err := m.conn.Write(buf.Bytes())
+
+	return len(p), err
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (m *MTProtoFrame) Logger() *zap.SugaredLogger {
+	return m.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (m *MTProtoFrame) LocalAddr() *net.TCPAddr {
+	return m.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (m *MTProtoFrame) RemoteAddr() *net.TCPAddr {
+	return m.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn instance.
+func (m *MTProtoFrame) Close() error {
+	return m.conn.Close()
+}
+
+// NewMTProtoFrame creates new PacketWrapper for underlying connection.
+func NewMTProtoFrame(conn StreamReadWriteCloser, seqNo int32) PacketReadWriteCloser {
+	return &MTProtoFrame{
+		conn:       conn,
+		logger:     conn.Logger().Named("mtproto-frame"),
+		readSeqNo:  seqNo,
+		writeSeqNo: seqNo,
+	}
+}

wrappers/mtproto_intermediate.go

@@ -0,0 +1,121 @@
+package wrappers
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"net"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/mtproto"
+)
+
+const mtprotoIntermediateQuickAckLength = 0x80000000
+
+// MTProtoIntermediate presents intermediate connection between client
+// and Telegram.
+type MTProtoIntermediate struct {
+	conn   StreamReadWriteCloser
+	opts   *mtproto.ConnectionOpts
+	logger *zap.SugaredLogger
+
+	readCounter  uint32
+	writeCounter uint32
+}
+
+func (m *MTProtoIntermediate) Read() ([]byte, error) {
+	defer func() {
+		m.readCounter++
+	}()
+
+	m.logger.Debugw("Read packet",
+		"simple_ack", m.opts.ReadHacks.SimpleAck,
+		"quick_ack", m.opts.ReadHacks.QuickAck,
+		"counter", m.readCounter,
+	)
+
+	buf := &bytes.Buffer{}
+	buf.Grow(4)
+
+	if _, err := io.CopyN(buf, m.conn, 4); err != nil {
+		return nil, errors.Annotate(err, "Cannot read message length")
+	}
+	length := binary.LittleEndian.Uint32(buf.Bytes())
+
+	m.logger.Debugw("Packet message length",
+		"simple_ack", m.opts.ReadHacks.SimpleAck,
+		"quick_ack", m.opts.ReadHacks.QuickAck,
+		"counter", m.readCounter,
+		"length", length,
+	)
+
+	if length > mtprotoIntermediateQuickAckLength {
+		m.opts.ReadHacks.QuickAck = true
+		length -= mtprotoIntermediateQuickAckLength
+	}
+
+	buf.Reset()
+	buf.Grow(int(length))
+	if _, err := io.CopyN(buf, m.conn, int64(length)); err != nil {
+		return nil, errors.Annotate(err, "Cannot read the message")
+	}
+
+	if length%4 != 0 {
+		length -= length % 4
+	}
+
+	return buf.Bytes()[:length], nil
+}
+
+func (m *MTProtoIntermediate) Write(p []byte) (int, error) {
+	defer func() {
+		m.writeCounter++
+	}()
+
+	m.logger.Debugw("Write packet",
+		"simple_ack", m.opts.WriteHacks.SimpleAck,
+		"quick_ack", m.opts.WriteHacks.QuickAck,
+		"counter", m.writeCounter,
+	)
+
+	if m.opts.ReadHacks.SimpleAck {
+		return m.conn.Write(p)
+	}
+
+	var length [4]byte
+	binary.LittleEndian.PutUint32(length[:], uint32(len(p)))
+
+	return m.conn.Write(append(length[:], p...))
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (m *MTProtoIntermediate) Logger() *zap.SugaredLogger {
+	return m.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (m *MTProtoIntermediate) LocalAddr() *net.TCPAddr {
+	return m.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (m *MTProtoIntermediate) RemoteAddr() *net.TCPAddr {
+	return m.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn instance.
+func (m *MTProtoIntermediate) Close() error {
+	return m.conn.Close()
+}
+
+// NewMTProtoIntermediate creates new PacketWrapper for intermediate
+// client connection.
+func NewMTProtoIntermediate(conn StreamReadWriteCloser, opts *mtproto.ConnectionOpts) PacketReadWriteCloser {
+	return &MTProtoIntermediate{
+		conn:   conn,
+		logger: conn.Logger().Named("mtproto-intermediate"),
+		opts:   opts,
+	}
+}

wrappers/mtproto_proxy.go

@@ -0,0 +1,164 @@
+package wrappers
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/mtproto"
+	"github.com/9seconds/mtg/mtproto/rpc"
+)
+
+// MTProtoProxy is a wrapper which creates/reads RPC responses from Telegram.
+type MTProtoProxy struct {
+	conn   PacketReadWriteCloser
+	req    *rpc.ProxyRequest
+	logger *zap.SugaredLogger
+
+	readCounter  uint32
+	writeCounter uint32
+}
+
+func (m *MTProtoProxy) Read() ([]byte, error) {
+	defer func() {
+		m.readCounter++
+	}()
+
+	m.logger.Debugw("Read packet",
+		"counter", m.readCounter,
+		"simple_ack", m.req.Options.WriteHacks.SimpleAck,
+		"quick_ack", m.req.Options.WriteHacks.QuickAck,
+	)
+
+	packet, err := m.conn.Read()
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot read packet")
+	}
+
+	m.logger.Debugw("Read packet length",
+		"counter", m.readCounter,
+		"simple_ack", m.req.Options.WriteHacks.SimpleAck,
+		"quick_ack", m.req.Options.WriteHacks.QuickAck,
+		"length", len(packet),
+	)
+
+	if len(packet) < 4 {
+		return nil, errors.Annotate(err, "Incorrect packet length")
+	}
+
+	tag, packet := packet[:4], packet[4:]
+	switch {
+	case bytes.Equal(tag, rpc.TagProxyAns):
+		return m.readProxyAns(packet)
+	case bytes.Equal(tag, rpc.TagSimpleAck):
+		return m.readSimpleAck(packet)
+	case bytes.Equal(tag, rpc.TagCloseExt):
+		return m.readCloseExt(packet)
+	}
+
+	return nil, errors.Errorf("Unknown RPC answer %v", tag)
+}
+
+func (m *MTProtoProxy) readProxyAns(data []byte) ([]byte, error) {
+	if len(data) < 12 {
+		return nil, errors.Errorf("Incorrect data of proxy answer: %d", len(data))
+	}
+	data = data[12:]
+
+	m.logger.Debugw("Read RPC_PROXY_ANS",
+		"counter", m.readCounter,
+		"length", len(data),
+	)
+
+	return data, nil
+}
+
+func (m *MTProtoProxy) readSimpleAck(data []byte) ([]byte, error) {
+	if len(data) != 12 {
+		return nil, errors.Errorf("Incorrect data of simple ack: %d", len(data))
+	}
+	data = data[8:12]
+	m.req.Options.WriteHacks.SimpleAck = true
+
+	m.logger.Debugw("Read RPC_SIMPLE_ACK",
+		"counter", m.readCounter,
+		"length", len(data),
+	)
+
+	return data, nil
+}
+
+func (m *MTProtoProxy) readCloseExt(data []byte) ([]byte, error) {
+	m.logger.Debugw("Read RPC_CLOSE_EXT", "counter", m.readCounter)
+
+	return nil, errors.New("Connection has been closed remotely by RPC call")
+}
+
+func (m *MTProtoProxy) Write(p []byte) (int, error) {
+	defer func() {
+		m.writeCounter++
+	}()
+
+	m.logger.Debugw("Write packet",
+		"length", len(p),
+		"counter", m.writeCounter,
+		"simple_ack", m.req.Options.ReadHacks.SimpleAck,
+		"quick_ack", m.req.Options.ReadHacks.QuickAck,
+	)
+
+	header, flags := m.req.MakeHeader(p)
+	if ce := m.logger.Desugar().Check(zap.DebugLevel, "RPC_PROXY_REQ header"); ce != nil {
+		ce.Write(
+			zap.Int("length", len(p)),
+			zap.Uint32("counter", m.writeCounter),
+			zap.Bool("simple_ack", m.req.Options.ReadHacks.QuickAck),
+			zap.Bool("quick_ack", m.req.Options.ReadHacks.SimpleAck),
+			zap.String("header", fmt.Sprintf("%v", header.Bytes())),
+			zap.Stringer("flags", flags),
+		)
+	}
+	header.Write(p)
+
+	if _, err := m.conn.Write(header.Bytes()); err != nil {
+		return 0, err
+	}
+
+	return len(p), nil
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (m *MTProtoProxy) Logger() *zap.SugaredLogger {
+	return m.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (m *MTProtoProxy) LocalAddr() *net.TCPAddr {
+	return m.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (m *MTProtoProxy) RemoteAddr() *net.TCPAddr {
+	return m.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn instance.
+func (m *MTProtoProxy) Close() error {
+	return m.conn.Close()
+}
+
+// NewMTProtoProxy creates new RPC wrapper.
+func NewMTProtoProxy(conn PacketReadWriteCloser, connOpts *mtproto.ConnectionOpts, adTag []byte) (PacketReadWriteCloser, error) {
+	req, err := rpc.NewProxyRequest(connOpts.ClientAddr, conn.LocalAddr(), connOpts, adTag)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot create new RPC proxy request")
+	}
+
+	return &MTProtoProxy{
+		conn:   conn,
+		logger: conn.Logger().Named("mtproto-proxy"),
+		req:    req,
+	}, nil
+}

wrappers/streamcipher.go

@@ -0,0 +1,65 @@
+package wrappers
+
+import (
+	"crypto/cipher"
+	"net"
+
+	"github.com/juju/errors"
+	"go.uber.org/zap"
+)
+
+// StreamCipher is a wrapper which encrypts/decrypts stream with AES-CTR
+// (as a part of obfuscated2 protocol).
+type StreamCipher struct {
+	encryptor cipher.Stream
+	decryptor cipher.Stream
+	conn      StreamReadWriteCloser
+	logger    *zap.SugaredLogger
+}
+
+func (s *StreamCipher) Read(p []byte) (int, error) {
+	n, err := s.conn.Read(p)
+	if err != nil {
+		return 0, errors.Annotate(err, "Cannot read stream ciphered data")
+	}
+	s.decryptor.XORKeyStream(p, p[:n])
+
+	return n, nil
+}
+
+func (s *StreamCipher) Write(p []byte) (int, error) {
+	encrypted := make([]byte, len(p))
+	s.encryptor.XORKeyStream(encrypted, p)
+
+	return s.conn.Write(encrypted)
+}
+
+// Logger returns an instance of the logger for this wrapper.
+func (s *StreamCipher) Logger() *zap.SugaredLogger {
+	return s.logger
+}
+
+// LocalAddr returns local address of the underlying net.Conn.
+func (s *StreamCipher) LocalAddr() *net.TCPAddr {
+	return s.conn.LocalAddr()
+}
+
+// RemoteAddr returns remote address of the underlying net.Conn.
+func (s *StreamCipher) RemoteAddr() *net.TCPAddr {
+	return s.conn.RemoteAddr()
+}
+
+// Close closes underlying net.Conn instance.
+func (s *StreamCipher) Close() error {
+	return s.conn.Close()
+}
+
+// NewStreamCipher creates new stream cipher wrapper.
+func NewStreamCipher(conn StreamReadWriteCloser, encryptor, decryptor cipher.Stream) StreamReadWriteCloser {
+	return &StreamCipher{
+		conn:      conn,
+		logger:    conn.Logger().Named("stream-cipher"),
+		encryptor: encryptor,
+		decryptor: decryptor,
+	}
+}

wrappers/streamcipherrwc.go

@@ -1,54 +0,0 @@
-package wrappers
-
-import (
-	"crypto/cipher"
-	"io"
-)
-
-// StreamCipherReadWriteCloser is a ReadWriteCloser which ciphers
-// incoming and outgoing data with givem cipher.Stream instances.
-type StreamCipherReadWriteCloser struct {
-	encryptor cipher.Stream
-	decryptor cipher.Stream
-	conn      io.ReadWriteCloser
-}
-
-// Read reads from connection
-func (c *StreamCipherReadWriteCloser) Read(p []byte) (n int, err error) {
-	n, err = c.conn.Read(p)
-	c.decryptor.XORKeyStream(p, p[:n])
-	return
-}
-
-// Write writes into connection.
-func (c *StreamCipherReadWriteCloser) Write(p []byte) (int, error) {
-	// This is to decrease an amount of allocations. Unfortunately, escape
-	// analysis in (at least Golang 1.10) is absolutely not perfect. For
-	// example, it understands that we want to have a slice locally, right?
-	// But since slice is effectively 2 ints + uintptr to [number]byte, the
-	// most heavyweight part is placed in heap.
-	buf := getBuffer()
-	defer putBuffer(buf)
-	buf.Grow(len(p))
-	buf.Write(p)
-
-	encrypted := buf.Bytes()
-	c.encryptor.XORKeyStream(encrypted, p)
-
-	return c.conn.Write(encrypted)
-}
-
-// Close closes underlying connection.
-func (c *StreamCipherReadWriteCloser) Close() error {
-	return c.conn.Close()
-}
-
-// NewStreamCipherRWC returns wrapper which transparently
-// encrypts/decrypts traffic with obfuscated2 protocol.
-func NewStreamCipherRWC(conn io.ReadWriteCloser, encryptor, decryptor cipher.Stream) io.ReadWriteCloser {
-	return &StreamCipherReadWriteCloser{
-		conn:      conn,
-		encryptor: encryptor,
-		decryptor: decryptor,
-	}
-}

wrappers/trafficrwc.go

@@ -1,39 +0,0 @@
-package wrappers
-
-import "io"
-
-// TrafficReadWriteCloser counts an amount of ingress/egress traffic by
-// calling given callbacks.
-type TrafficReadWriteCloser struct {
-	conn          io.ReadWriteCloser
-	readCallback  func(int)
-	writeCallback func(int)
-}
-
-// Read reads from connection
-func (t *TrafficReadWriteCloser) Read(p []byte) (n int, err error) {
-	n, err = t.conn.Read(p)
-	t.readCallback(n)
-	return
-}
-
-// Write writes into connection.
-func (t *TrafficReadWriteCloser) Write(p []byte) (n int, err error) {
-	n, err = t.conn.Write(p)
-	t.writeCallback(n)
-	return
-}
-
-// Close closes underlying connection.
-func (t *TrafficReadWriteCloser) Close() error {
-	return t.conn.Close()
-}
-
-// NewTrafficRWC wraps ReadWriteCloser to have read/write callbacks.
-func NewTrafficRWC(conn io.ReadWriteCloser, readCallback, writeCallback func(int)) io.ReadWriteCloser {
-	return &TrafficReadWriteCloser{
-		conn:          conn,
-		readCallback:  readCallback,
-		writeCallback: writeCallback,
-	}
-}

wrappers/wrap.go

@@ -0,0 +1,111 @@
+package wrappers
+
+import (
+	"io"
+	"net"
+
+	"go.uber.org/zap"
+)
+
+// Wrap is a base interface for all wrappers in this package.
+type Wrap interface {
+	Logger() *zap.SugaredLogger
+	LocalAddr() *net.TCPAddr
+	RemoteAddr() *net.TCPAddr
+}
+
+// Writer is a base interface for writers of this package.
+type Writer interface {
+	io.Writer
+	Wrap
+}
+
+// Closer is a base interface for wrappers of this package which can
+// close connections.
+type Closer interface {
+	io.Closer
+	Wrap
+}
+
+// WriteCloser is a base interface for wrappers of this package which
+// can write to and close connections.
+type WriteCloser interface {
+	io.Closer
+	Writer
+}
+
+// StreamReader is a base interface for wrappers which can read from the
+// stream.
+type StreamReader interface {
+	io.Reader
+	Wrap
+}
+
+// StreamReadCloser is a base interface for wrappers which can read from
+// and close the connections.
+type StreamReadCloser interface {
+	io.Closer
+	StreamReader
+}
+
+// StreamReadWriter is a base interface for wrappers which can read from
+// and write to the connections.
+type StreamReadWriter interface {
+	io.Writer
+	StreamReader
+}
+
+// StreamWriteCloser is a base interface for wrappers which can write to
+// and close the connections.
+type StreamWriteCloser interface {
+	io.WriteCloser
+	Wrap
+}
+
+// StreamReadWriteCloser is a base interface for stream processors.
+type StreamReadWriteCloser interface {
+	io.Closer
+	StreamReadWriter
+}
+
+// PacketReader is a base interface for wrappers which reads 'packets'.
+// packets are atoms so you either get a packet or you get an error You
+// cannot resume reading from packet.
+type PacketReader interface {
+	Read() ([]byte, error)
+	Wrap
+}
+
+// PacketWriter is a base interface for wrappers which can write packets.
+type PacketWriter interface {
+	io.Writer
+	Wrap
+}
+
+// PacketReadWriter is a base interface for wrappers which can read from
+// and write packets.
+type PacketReadWriter interface {
+	io.Writer
+	PacketReader
+}
+
+// PacketReadCloser is a base interface for wrappers which can read
+// packets and close the connection.
+type PacketReadCloser interface {
+	io.Closer
+	PacketReader
+}
+
+// PacketWriteCloser is a base interface for wrappers which can write
+// packets and close the connection.
+type PacketWriteCloser interface {
+	io.Writer
+	io.Closer
+	Wrap
+}
+
+// PacketReadWriteCloser is a base interface for packet processors.
+type PacketReadWriteCloser interface {
+	io.Closer
+	PacketReadWriter
+}