don't kill agent connection on invalid RFH

coadler · coadler · commit 16eef967dc72 · 2024-04-03T22:08:57.000Z
diff --git a/tailnet/coordinator.go b/tailnet/coordinator.go
@@ -717,7 +717,12 @@ func (c *core) handleReadyForHandshakeLocked(src *peer, rfhs []*proto.Coordinate
 		}
 
 		if !c.tunnels.tunnelExists(src.id, dstID) {
-			return xerrors.Errorf("tunnel does not exist between %s and %s", src.id.String(), dstID.String())
+			// We intentionally do not return an error here, since it's
+			// inherently racy. It's possible for a source to connect, then
+			// subsequently disconnect before the agent has sent back the RFH.
+			// Since this could potentially happen to a non-malicious agent, we
+			// don't want to kill its connection.
+			continue
 		}
 
 		dst, ok := c.peers[dstID]

Original file line number	Diff line number	Diff line change
`@@ -717,7 +717,12 @@ func (c core) handleReadyForHandshakeLocked(src peer, rfhs []*proto.Coordinate`
`717`	`717`	`}`
`718`	`718`
`719`	`719`	`if !c.tunnels.tunnelExists(src.id, dstID) {`
`720`		`- return xerrors.Errorf("tunnel does not exist between %s and %s", src.id.String(), dstID.String())`
	`720`	`+ // We intentionally do not return an error here, since it's`
	`721`	`+ // inherently racy. It's possible for a source to connect, then`
	`722`	`+ // subsequently disconnect before the agent has sent back the RFH.`
	`723`	`+ // Since this could potentially happen to a non-malicious agent, we`
	`724`	`+ // don't want to kill its connection.`
	`725`	`+ continue`
`721`	`726`	`}`
`722`	`727`
`723`	`728`	`dst, ok := c.peers[dstID]`