From 671809420f0adca93f3686af46711fece8f16160 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Wed, 6 Jul 2016 18:12:08 +0200
Subject: [PATCH] auth: Wait for the connection to the carbon server to be
 established

Doing a non-blocking `connect()` immediately followed by a `write()`
cause the `write()` to fail with `ENOTCONN` on FreeBSD.
This commit instead wait for the `connect()` operation to finish
using `poll()` with a short timeout if it returned `EINPROGRESS`,
so that either we have a connected socket to write to, or we fail.
---
 pdns/auth-carbon.cc |  7 ++++---
 pdns/sstuff.hh      | 20 +++++++++++++++++---
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/pdns/auth-carbon.cc b/pdns/auth-carbon.cc
index c721cc0155..17a43b365d 100644
--- a/pdns/auth-carbon.cc
+++ b/pdns/auth-carbon.cc
@@ -46,11 +46,12 @@ try
 
     for (const auto& carbonServer : carbonServers) {
       ComboAddress remote(carbonServer, 2003);
-      Socket s(remote.sin4.sin_family, SOCK_STREAM);
-      s.setNonBlocking();
-      s.connect(remote);  // we do the connect so the attempt happens while we gather stats
 
       try {
+        Socket s(remote.sin4.sin_family, SOCK_STREAM);
+        s.setNonBlocking();
+        s.connect(remote, 2);
+
         writen2WithTimeout(s.getHandle(), msg.c_str(), msg.length(), 2);
       } catch (runtime_error &e){
         L<<Logger::Warning<<"Unable to write data to carbon server at "<<remote.toStringWithPort()<<": "<<e.what()<<endl;
diff --git a/pdns/sstuff.hh b/pdns/sstuff.hh
index 274577c92e..a586ec30dc 100644
--- a/pdns/sstuff.hh
+++ b/pdns/sstuff.hh
@@ -137,10 +137,24 @@ public:
   }
 #endif
   //! Connect the socket to a specified endpoint
-  void connect(const ComboAddress &ep)
+  void connect(const ComboAddress &ep, int timeout=0)
   {
-    if(::connect(d_socket,(struct sockaddr *)&ep, ep.getSocklen()) < 0 && errno != EINPROGRESS)
-      throw NetworkError("While connecting to "+ep.toStringWithPort()+": "+string(strerror(errno)));
+    if(::connect(d_socket,(struct sockaddr *)&ep, ep.getSocklen()) < 0) {
+      if(errno == EINPROGRESS) {
+        if (timeout > 0) {
+          /* if a timeout is provided, we wait until the connection has been established */
+          int res = waitForRWData(d_socket, false, timeout, 0);
+          if (res == 0) {
+            throw NetworkError("timeout while connecting to "+ep.toStringWithPort());
+          } else if (res < 0) {
+            throw NetworkError("while waiting to connect to "+ep.toStringWithPort()+": "+string(strerror(errno)));
+          }
+        }
+      }
+      else {
+        throw NetworkError("While connecting to "+ep.toStringWithPort()+": "+string(strerror(errno)));
+      }
+    }
   }
 
 
-- 
2.47.2