From 8a8f6e58a371bae661273d39ed0eb307cfc84190 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 4 Oct 2019 10:44:33 +0200
Subject: [PATCH] dnsdist: Also apply SO_BINDTODEVICE to TCP sockets

---
 pdns/dnsdist-tcp.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index 403fbf6017..a387bee4e7 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -79,6 +79,12 @@ static std::unique_ptr<Socket> setupTCPDownstream(shared_ptr<DownstreamState>& d
         if (ds->ipBindAddrNoPort) {
           SSetsockopt(result->getHandle(), SOL_IP, IP_BIND_ADDRESS_NO_PORT, 1);
         }
+#endif
+#ifdef SO_BINDTODEVICE
+        int res = setsockopt(result->getHandle(), SOL_SOCKET, SO_BINDTODEVICE, ds->sourceItfName.c_str(), ds->sourceItfName.length());
+        if (res != 0) {
+          vinfolog("Error setting up the interface on backend TCP socket '%s': %s", ds->getNameWithAddr(), stringerror());
+        }
 #endif
         result->bind(ds->sourceAddr, false);
       }
-- 
2.47.2