Move all wrappers

2026-09-01 16:01:55 +03:00 · 2018-07-07 18:05:24 +03:00
parent a7d46727ba
commit 4262e5f5de
4 changed files with 143 additions and 180 deletions
@@ -0,0 +1,94 @@
+package wrappers
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/md5"
+	"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}
+
+func NewMiddleProxyCipher(conn WrapStreamReadWriteCloser, req *rpc.NonceRequest, resp *rpc.NonceResponse, secret []byte) WrapStreamReadWriteCloser {
+	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 NewWrapBlockCipher(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:])
+	sha1sum := sha1.Sum(data)
+
+	key := append(md5sum[:12], sha1sum[:]...)
+	iv := md5.Sum(data[2:])
+
+	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)
+}