peer: Remove getheaders response deadline.

This removes the response dealine for getheaders since there is no
guaranteed response if the remote peer does not have any headers for the
locator.

Also, while here, modify the debug logging to only log a deadline was
added when it actually was.

peer/peer.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2013-2016 The btcsuite developers
-// Copyright (c) 2016-2020 The Decred developers
+// Copyright (c) 2016-2021 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -1090,40 +1090,45 @@ func (p *Peer) maybeAddDeadline(pendingResponses map[string]time.Time, msgCmd st
 	// sent asynchronously and as a result of a long backlog of messages,
 	// such as is typical in the case of initial block download, the
 	// response won't be received in time.
-	log.Debugf("Adding deadline for command %s for peer %s", msgCmd, p.addr)
-
+	//
+	// Also, getheaders is intentionally ignored since there is no guaranteed
+	// response if the remote peer does not have any headers for the locator.
+	var addedDeadline bool
 	deadline := time.Now().Add(stallResponseTimeout)
 	switch msgCmd {
 	case wire.CmdVersion:
 		// Expects a verack message.
 		pendingResponses[wire.CmdVerAck] = deadline
+		addedDeadline = true
 
 	case wire.CmdMemPool:
 		// Expects an inv message.
 		pendingResponses[wire.CmdInv] = deadline
+		addedDeadline = true
 
 	case wire.CmdGetBlocks:
 		// Expects an inv message.
 		pendingResponses[wire.CmdInv] = deadline
+		addedDeadline = true
 
 	case wire.CmdGetData:
 		// Expects a block, tx, or notfound message.
 		pendingResponses[wire.CmdBlock] = deadline
 		pendingResponses[wire.CmdTx] = deadline
 		pendingResponses[wire.CmdNotFound] = deadline
-
-	case wire.CmdGetHeaders:
-		// Expects a headers message.  Use a longer deadline since it
-		// can take a while for the remote peer to load all of the
-		// headers.
-		deadline = time.Now().Add(stallResponseTimeout * 3)
-		pendingResponses[wire.CmdHeaders] = deadline
+		addedDeadline = true
 
 	case wire.CmdGetMiningState:
 		pendingResponses[wire.CmdMiningState] = deadline
+		addedDeadline = true
 
 	case wire.CmdGetInitState:
 		pendingResponses[wire.CmdInitState] = deadline
+		addedDeadline = true
+	}
+
+	if addedDeadline {
+		log.Debugf("Adding deadline for command %s for peer %s", msgCmd, p.addr)
 	}
 }