Mass ban of all incoming peers

[proninyaroslav]

Linked issue: #7734

libtorrent version (or branch): libtorrent4j, libtorrent 2.0 master

platform/architecture: Android arm64

I use libtorrent4j wrapper for Java in my Android app, which uses libtorrent 2.0 master branch for building. Over the last year, users have started complaining that torrent downloads are abruptly interrupted. This doesn't happen to everyone. In the log that was sent to me, I found that all incoming peers were banned for some reason:

Log

2024-09-19 20:40:22.676 [PEER_LOG] [INCOMING] [INCOMING_CONNECTION] ep: 78.37.3.216:49632 type: uTP seed: 0 p: 0x0 local: 0.0.0.0:43364
2024-09-19 20:40:22.677 [PEER_LOG] [INFO] [CONSTRUCT] bt_peer_connection
2024-09-19 20:40:22.677 [PEER_LOG] [INFO] [SET_PEER_CLASS] a: 78.37.3.216
2024-09-19 20:40:22.677 [PEER_LOG] [INFO] [CLASS] global 
2024-09-19 20:40:22.677 [PEER_LOG] [INCOMING] [ASYNC_READ] max: 104 bytes
2024-09-19 20:40:22.729 [PEER_LOG] [INCOMING] [ON_RECEIVE_DATA] bytes: 68 
2024-09-19 20:40:22.730 [PEER_LOG] [INCOMING] [READ] 68 bytes
2024-09-19 20:40:22.730 [PEER_LOG] [INCOMING_MESSAGE] [HANDSHAKE] BitTorrent protocol
2024-09-19 20:40:22.730 [PEER_LOG] [INCOMING_MESSAGE] [EXTENSIONS] 0000000000000000000000000000000000000000000100000000000000000101 ext: DHT FAST extension 
2024-09-19 20:40:22.730 [PEER_LOG] [INFO] [ATTACH] attached to torrent
2024-09-19 20:40:22.730 [PEER_LOG] [INFO] [CONNECTION_CLOSED] op: 1 ERROR: (libtorrent:91) peer banned
2024-09-19 20:40:22.730 [TORRENT_LOG] CLOSING CONNECTION "78.37.3.216:49632" peer list full connections: 19 limit: 40

and only in 3 cases out of 71 it was indicated that the peer was banned because of too many corrupted piece:

Log

2024-09-19 20:38:30.468 [PEER_LOG] [INFO] [FILE_ASYNC_WRITE_COMPLETE] piece: 9 s: fc000 l: 4000 e: Success
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ON_RECEIVE_DATA] bytes: 1418 
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [READ] 1418 bytes
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ASYNC_READ] max: 25446 bytes
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ON_RECEIVE_DATA] bytes: 7090 
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [READ] 7090 bytes
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ASYNC_READ] max: 18356 bytes
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ON_RECEIVE_DATA] bytes: 2836 
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [READ] 2836 bytes
2024-09-19 20:38:30.469 [PEER_LOG] [INCOMING] [ASYNC_READ] max: 15520 bytes
2024-09-19 20:38:30.469 [TORRENT_LOG] *** PIECE_FINISHED [ p: 9 | chk: failed | size: 1048576 ]
2024-09-19 20:38:30.469 [TORRENT_LOG] *** BANNING PEER: "5.253.144.209:37839" Too many corrupt pieces
2024-09-19 20:38:30.469 [PEER_LOG] [INFO] [BANNING_PEER] Too many corrupt pieces
2024-09-19 20:38:30.469 [PEER_LOG] [INFO] [CONNECTION_CLOSED] op: 1 ERROR: (libtorrent:93) too many corrupt pieces

To understand the reason I decided to roll back the libtorrent4j version (current 2.1.0-33 from Oct 30, 2024). I found that the problem started with version 2.1.0-27 from Jan 14, 2023. However, version 2.0.6-26 from Jun 6, 2022 doesn't have this problem, there are no mass bans of peers. libtorren4j uses the master branch of libtorren, so all release dates are relevant for the master branch of the same date.

I also attach full versions of the logs, the one where there is a problem and the one where there is no problem:

problem_version_log.txt
prev_version_log.txt