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make the passive protocol detection harder

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Alexander Bersenev
2018-07-10 15:48:39 +05:00
parent 520a26aa89
commit 8e79dacd26
1 changed files with 39 additions and 6 deletions
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45
mtprotoproxy.py
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@@ -431,11 +431,6 @@ class MTProtoIntermediateFrameStreamReader(LayeredStreamReaderBase):
msg_len -= 0x80000000
data = await self.upstream.readexactly(msg_len)
if msg_len % 4 != 0:
cut_border = msg_len - (msg_len % 4)
data = data[:cut_border]
return data, extra
@@ -447,6 +442,38 @@ class MTProtoIntermediateFrameStreamWriter(LayeredStreamWriterBase):
return self.upstream.write(int.to_bytes(len(data), 4, 'little') + data)
class MTProtoSecureIntermediateFrameStreamReader(LayeredStreamReaderBase):
async def read(self, buf_size):
msg_len_bytes = await self.upstream.readexactly(4)
msg_len = int.from_bytes(msg_len_bytes, "little")
extra = {}
if msg_len > 0x80000000:
extra["QUICKACK_FLAG"] = True
msg_len -= 0x80000000
data = await self.upstream.readexactly(msg_len)
if msg_len % 4 != 0:
cut_border = msg_len - (msg_len % 4)
data = data[:cut_border]
return data, extra
class MTProtoSecureIntermediateFrameStreamWriter(LayeredStreamWriterBase):
def write(self, data, extra={}):
MAX_PADDING_LEN = 4
if extra.get("SIMPLE_ACK"):
# TODO: make this unpredictable
return self.upstream.write(data)
else:
padding_len = random.randrange(MAX_PADDING_LEN)
padding = bytearray([random.randrange(256) for i in range(padding_len)])
padded_data_len_bytes = int.to_bytes(len(data) + padding_len, 4, 'little')
return self.upstream.write(padded_data_len_bytes + data + padding)
class ProxyReqStreamReader(LayeredStreamReaderBase):
async def read(self, msg):
RPC_PROXY_ANS = b"\x0d\xda\x03\x44"
@@ -505,6 +532,7 @@ class ProxyReqStreamWriter(LayeredStreamWriterBase):
FLAG_HAS_AD_TAG = 0x8
FLAG_MAGIC = 0x1000
FLAG_EXTMODE2 = 0x20000
FLAG_PAD = 0x8000000
FLAG_INTERMEDIATE = 0x20000000
FLAG_ABRIDGED = 0x40000000
FLAG_QUICKACK = 0x80000000
@@ -519,6 +547,8 @@ class ProxyReqStreamWriter(LayeredStreamWriterBase):
flags |= FLAG_ABRIDGED
elif self.proto_tag == PROTO_TAG_INTERMEDIATE:
flags |= FLAG_INTERMEDIATE
elif self.proto_tag == PROTO_TAG_SECURE:
flags |= FLAG_INTERMEDIATE | FLAG_PAD
if extra.get("QUICKACK_FLAG"):
flags |= FLAG_QUICKACK
@@ -880,9 +910,12 @@ async def handle_client(reader_clt, writer_clt):
if proto_tag == PROTO_TAG_ABRIDGED:
reader_clt = MTProtoCompactFrameStreamReader(reader_clt)
writer_clt = MTProtoCompactFrameStreamWriter(writer_clt)
elif proto_tag in (PROTO_TAG_INTERMEDIATE, PROTO_TAG_SECURE):
elif proto_tag == PROTO_TAG_INTERMEDIATE:
reader_clt = MTProtoIntermediateFrameStreamReader(reader_clt)
writer_clt = MTProtoIntermediateFrameStreamWriter(writer_clt)
elif proto_tag == PROTO_TAG_SECURE:
reader_clt = MTProtoSecureIntermediateFrameStreamReader(reader_clt)
writer_clt = MTProtoSecureIntermediateFrameStreamWriter(writer_clt)
else:
return