From 89e0087450e73ea2336f56c0f7024f4741eaeba0 Mon Sep 17 00:00:00 2001
From: JINMEI Tatuya <jinmei@isc.org>
Date: Wed, 8 May 2013 23:05:14 -0700
Subject: [PATCH] [master] exit from SyncUDPServer::handleRead immediately if
 stopped.

while not really correct, this seems to work as a workaround for the crash
problem reported in #2946.
okayed on jabber.
---
 src/lib/asiodns/sync_udp_server.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/lib/asiodns/sync_udp_server.cc b/src/lib/asiodns/sync_udp_server.cc
index 9a066911a6..989484f4eb 100644
--- a/src/lib/asiodns/sync_udp_server.cc
+++ b/src/lib/asiodns/sync_udp_server.cc
@@ -75,6 +75,15 @@ SyncUDPServer::scheduleRead() {
 
 void
 SyncUDPServer::handleRead(const asio::error_code& ec, const size_t length) {
+    // If the server has been stopped, it could even have been destroyed
+    // by the time of this call.  We'll solve this problem in #2946, but
+    // until then we exit as soon as possible without accessing any other
+    // invalidated fields (note that referencing stopped_ is also incorrect,
+    // but experiments showed it often keeps the original value in practice,
+    // so we live with it until the complete fix).
+    if (stopped_) {
+        return;
+    }
     if (ec) {
         using namespace asio::error;
         const asio::error_code::value_type err_val = ec.value();