From: Matt Joiner <anacrolix@gmail.com>
Date: Fri, 23 Aug 2019 02:19:28 +0000 (+1000)
Subject: Fix a crash when receiving a request when we don't yet have the torrent info
X-Git-Tag: v1.7.1^0
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=95a521bad6f5cc17d6c40f888add262a6c40fc20;p=btrtrc.git

Fix a crash when receiving a request when we don't yet have the torrent info
---

diff --git a/connection.go b/connection.go
index 397be949..8a137e95 100644
--- a/connection.go
+++ b/connection.go
@@ -1025,10 +1025,6 @@ func (c *connection) reject(r request) {
 
 func (c *connection) onReadRequest(r request) error {
 	requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
-	if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
-		torrent.Add("bad requests received", 1)
-		return errors.New("bad request")
-	}
 	if _, ok := c.PeerRequests[r]; ok {
 		torrent.Add("duplicate requests received", 1)
 		return nil
@@ -1056,6 +1052,11 @@ func (c *connection) onReadRequest(r request) error {
 		requestsReceivedForMissingPieces.Add(1)
 		return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
 	}
+	// Check this after we know we have the piece, so that the piece length will be known.
+	if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
+		torrent.Add("bad requests received", 1)
+		return errors.New("bad request")
+	}
 	if c.PeerRequests == nil {
 		c.PeerRequests = make(map[request]struct{}, maxRequests)
 	}