From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 27 Jan 2022 04:09:05 +0000 (+1100)
Subject: Ban peers for dirtying pieces if they are solely responsible
X-Git-Tag: v1.42.0~8^2^2~10
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=60057327b332ef9fdfe37f7240f69b3c08cc3549;p=btrtrc.git

Ban peers for dirtying pieces if they are solely responsible
---

diff --git a/torrent.go b/torrent.go
index 22b4bb57..d6ff2dbc 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2042,8 +2042,14 @@ func (t *Torrent) pieceHashed(piece pieceIndex, passed bool, hashIoErr error) {
 
 			if len(bannableTouchers) >= 1 {
 				c := bannableTouchers[0]
-				log.Printf("would have banned %v for touching piece %v after failed piece check", c.remoteIp(), piece)
-				if false {
+				if len(bannableTouchers) != 1 {
+					t.logger.Levelf(log.Warning, "would have banned %v for touching piece %v after failed piece check", c.remoteIp(), piece)
+				} else {
+					// Turns out it's still useful to ban peers like this because if there's only a
+					// single peer for a piece, and we never progress that piece to completion, we
+					// will never smart-ban them. Discovered in
+					// https://github.com/anacrolix/torrent/issues/715.
+					t.logger.Levelf(log.Warning, "banning %v for being sole dirtier of piece %v after failed piece check", c.remoteIp(), piece)
 					t.cl.banPeerIP(c.remoteIp())
 					c.drop()
 				}