From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 24 Apr 2020 10:45:45 +0000 (+0200)
Subject: dnsdist: Gracefully handle a failure to remove FD on (re)-connection
X-Git-Tag: dnsdist-1.5.0-rc2~10^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F9057%2Fhead;p=thirdparty%2Fpdns.git

dnsdist: Gracefully handle a failure to remove FD on (re)-connection

When more than one socket per backend is used, we might not have
added all the socket descriptors to the multiplexer and that's fine.
---

diff --git a/pdns/dnsdistdist/dnsdist-backend.cc b/pdns/dnsdistdist/dnsdist-backend.cc
index 606977c098..fbce5dd708 100644
--- a/pdns/dnsdistdist/dnsdist-backend.cc
+++ b/pdns/dnsdistdist/dnsdist-backend.cc
@@ -79,8 +79,14 @@ bool DownstreamState::reconnect()
     for (auto& fd : sockets) {
       if (fd != -1) {
         if (sockets.size() > 1) {
-          std::lock_guard<std::mutex> lock(socketsLock);
-          mplexer->removeReadFD(fd);
+          try {
+            std::lock_guard<std::mutex> lock(socketsLock);
+            mplexer->removeReadFD(fd);
+          }
+          catch (const FDMultiplexerException& e) {
+            /* some sockets might not have been added to the multiplexer
+               yet, that's fine */
+          }
         }
         /* shutdown() is needed to wake up recv() in the responderThread */
         shutdown(fd, SHUT_RDWR);