From a23538429a66c392498bb39c8b95931ff99e2c49 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 28 May 2018 18:29:58 +0200
Subject: [PATCH] dnsdist: Mark the remote member of DownstreamState as const

---
 pdns/dnsdist.cc | 13 +++++++++++--
 pdns/dnsdist.hh |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index 44ec64f42..c8e0ead05 100644
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -1074,7 +1074,8 @@ static ssize_t udpClientSendRequestToBackend(DownstreamState* ss, const int sd,
     struct msghdr msgh;
     struct iovec iov;
     char cbuf[256];
-    fillMSGHdr(&msgh, &iov, cbuf, sizeof(cbuf), const_cast<char*>(request), requestLen, &ss->remote);
+    ComboAddress remote(ss->remote);
+    fillMSGHdr(&msgh, &iov, cbuf, sizeof(cbuf), const_cast<char*>(request), requestLen, &remote);
     addCMsgSrcAddr(&msgh, cbuf, &ss->sourceAddr, ss->sourceItf);
     result = sendmsg(sd, &msgh, 0);
   }
@@ -1688,7 +1689,15 @@ try
   }
 
   string reply;
-  sock.recvFrom(reply, ds.remote);
+  ComboAddress from;
+  sock.recvFrom(reply, from);
+
+  /* we are using a connected socket but hey.. */
+  if (from != ds.remote) {
+    if (g_verboseHealthChecks)
+      infolog("Invalid health check response received from %s, expecting one from %s", from.toStringWithPort(), ds.remote.toStringWithPort());
+    return false;
+  }
 
   const dnsheader * responseHeader = reinterpret_cast<const dnsheader *>(reply.c_str());
 
diff --git a/pdns/dnsdist.hh b/pdns/dnsdist.hh
index 96a050b8d..e478a09cf 100644
--- a/pdns/dnsdist.hh
+++ b/pdns/dnsdist.hh
@@ -503,7 +503,7 @@ struct DownstreamState
   std::mutex socketsLock;
   std::unique_ptr<FDMultiplexer> mplexer{nullptr};
   std::thread tid;
-  ComboAddress remote;
+  const ComboAddress remote;
   QPSLimiter qps;
   vector<IDState> idStates;
   ComboAddress sourceAddr;
-- 
2.40.0