From 38d28c3f4ab47ddcb8a1c0069964b723c86abc8f Mon Sep 17 00:00:00 2001
From: Audrius Butkevicius <audrius.butkevicius@gmail.com>
Date: Fri, 11 Nov 2016 22:23:48 +0000
Subject: [PATCH] lib/relay: Close invitation channel in all error cases (fixes
 #3726)

---
 cmd/syncthing/main.go           |  2 ++
 lib/connections/relay_listen.go |  3 ++-
 lib/relay/client/dynamic.go     |  3 +--
 lib/relay/client/static.go      | 14 ++++++++++----
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/cmd/syncthing/main.go b/cmd/syncthing/main.go
index efee5101b..f61f90bcb 100644
--- a/cmd/syncthing/main.go
+++ b/cmd/syncthing/main.go
@@ -47,6 +47,8 @@ import (
 	"github.com/syncthing/syncthing/lib/upgrade"
 
 	"github.com/thejerf/suture"
+
+	_ "net/http/pprof" // Need to import this to support STPROFILER.
 )
 
 var (
diff --git a/lib/connections/relay_listen.go b/lib/connections/relay_listen.go
index fd8e6faaf..7fc67b62b 100644
--- a/lib/connections/relay_listen.go
+++ b/lib/connections/relay_listen.go
@@ -44,6 +44,7 @@ func (t *relayListener) Serve() {
 	t.mut.Unlock()
 
 	clnt, err := client.NewClient(t.uri, t.tlsCfg.Certificates, nil, 10*time.Second)
+	invitations := clnt.Invitations()
 	if err != nil {
 		t.mut.Lock()
 		t.err = err
@@ -62,7 +63,7 @@ func (t *relayListener) Serve() {
 
 	for {
 		select {
-		case inv, ok := <-t.client.Invitations():
+		case inv, ok := <-invitations:
 			if !ok {
 				return
 			}
diff --git a/lib/relay/client/dynamic.go b/lib/relay/client/dynamic.go
index 7100feb02..5e83c5144 100644
--- a/lib/relay/client/dynamic.go
+++ b/lib/relay/client/dynamic.go
@@ -48,6 +48,7 @@ func newDynamicClient(uri *url.URL, certs []tls.Certificate, invitations chan pr
 }
 
 func (c *dynamicClient) Serve() {
+	defer c.cleanup()
 	c.mut.Lock()
 	c.stop = make(chan struct{})
 	c.mut.Unlock()
@@ -75,8 +76,6 @@ func (c *dynamicClient) Serve() {
 		return
 	}
 
-	defer c.cleanup()
-
 	var addrs []string
 	for _, relayAnn := range ann.Relays {
 		ruri, err := url.Parse(relayAnn.URL)
diff --git a/lib/relay/client/static.go b/lib/relay/client/static.go
index 123a6339a..07ca26554 100644
--- a/lib/relay/client/static.go
+++ b/lib/relay/client/static.go
@@ -63,6 +63,7 @@ func newStaticClient(uri *url.URL, certs []tls.Certificate, invitations chan pro
 }
 
 func (c *staticClient) Serve() {
+	defer c.cleanup()
 	c.stop = make(chan struct{})
 	c.stopped = make(chan struct{})
 	defer close(c.stopped)
@@ -156,10 +157,6 @@ func (c *staticClient) Serve() {
 			} else {
 				c.err = nil
 			}
-			if c.closeInvitationsOnFinish {
-				close(c.invitations)
-				c.invitations = make(chan protocol.SessionInvitation)
-			}
 			c.mut.Unlock()
 			return
 
@@ -209,6 +206,15 @@ func (c *staticClient) Invitations() chan protocol.SessionInvitation {
 	return inv
 }
 
+func (c *staticClient) cleanup() {
+	c.mut.Lock()
+	if c.closeInvitationsOnFinish {
+		close(c.invitations)
+		c.invitations = make(chan protocol.SessionInvitation)
+	}
+	c.mut.Unlock()
+}
+
 func (c *staticClient) connect() error {
 	if c.uri.Scheme != "relay" {
 		return fmt.Errorf("Unsupported relay schema: %v", c.uri.Scheme)