CODEWITHSUNDEEP
bittorrent
Ray_Write
Ray_Write

Reputation: 131

Unknown Bittorrent Message

I have been receiving an odd/unknown message while attempting to communicate with some bittorrent peers. In this particular case I am in the middle of downloading pieces and all of a sudden this new/odd message pops up in front of a piece response.The message is odd because it doesn't appear to follow the protocol, all messages are supposed to look like this

'<length prefix><message ID><payload>'

length prefix is 4 bytes, message id is 1 byte and the payload. I am including a capture to show what I mean, on line 509 of the capture you will see a request for a piece, on line 510 you will see the beginning of the response.

The first 4 bytes of the response are 00 00 00 00, ie 0 length message (Which is causing me issues), the next 4 bytes are the actual length of the message which is 30. The actual response to the piece request starts on line 513, so I get the piece I was requesting but this new/odd message is messing me up. I'm certain I can find a workaround but I would really like to understand what this means.

Also, I have no idea what the actual message means, and cannot find any information about it anywhere.

Here is the Wireshark capture.

https://1drv.ms/u/s!Agj06pa-wu0tnFqsYn_KnHmVz3x2

Upvotes: 2

Views: 345

Answers (2)

the8472
the8472

Reputation: 43125

The first 4 bytes of the response are 00 00 00 00, ie 0 length message (Which is causing me issues)

The bittorrent spec says

Messages of length zero are keepalives, and ignored.

Upvotes: 1

Encombe
Encombe

Reputation: 2089

Data from packet 510: 

0000   00 00 00 00 00 00 00 1e 14 01 64 35 3a 61 64 64  ..........d5:add
0010   65 64 36 3a 63 f2 7a 48 17 f4 37 3a 64 72 6f 70  ed6:c.zH..7:drop
0020   70 65 64 30 3a 65                                ped0:e

00 00 00 00 4 bytes keep-alive message

00 00 00 1e message length 30 bytes
14 message type extended message (BEP10)
01 extended message ID = 1 as specified by the previous extension handshake: ut_pex

64 35 3a 61 64 64 65 64 36 3a 63 f2 7a 48 17 f4 37 3a 64 72 6f 70 70 65 64 30 3a 65 d5:added6:c.zH..7:dropped0:e
ut_pex message data (bencoded) 

d
 5:added
  6:c.zH..
 7:dropped
  0:
e

ut_pex message data (bencoded with added white space)

Upvotes: 1

Related Questions