From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 14 Mar 2016 09:22:08 +0000 (+0100)
Subject: dnsdist: Add more information when readn2 fails because of EAGAIN
X-Git-Tag: dnsdist-1.0.0-beta1~119^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F3564%2Fhead;p=thirdparty%2Fpdns.git

dnsdist: Add more information when readn2 fails because of EAGAIN
---

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index 2cb75474b7..d4320e7aab 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -160,7 +160,13 @@ void* tcpClientThread(int pipefd)
   for(;;) {
     ConnectionInfo* citmp, ci;
 
-    readn2(pipefd, &citmp, sizeof(citmp));
+    try {
+      readn2(pipefd, &citmp, sizeof(citmp));
+    }
+    catch(const std::runtime_error& e) {
+      throw std::runtime_error("Error reading from TCP acceptor pipe (" + std::to_string(pipefd) + ") in " + std::string(isNonBlocking(pipefd) ? "non-blocking" : "blocking") + " mode: " + e.what());
+    }
+
     --g_tcpclientthreads->d_queued;
     ci=*citmp;
     delete citmp;    
@@ -366,7 +372,7 @@ void* tcpClientThread(int pipefd)
 	  break;
 	}
 
-	int dsock;
+	int dsock = -1;
 	if(sockets.count(ds->remote) == 0) {
 	  dsock=sockets[ds->remote]=setupTCPDownstream(ds);
 	}
@@ -387,6 +393,7 @@ void* tcpClientThread(int pipefd)
         if (ds->retries > 0 && downstream_failures > ds->retries) {
           vinfolog("Downstream connection to %s failed %d times in a row, giving up.", ds->getName(), downstream_failures);
           close(dsock);
+          dsock=-1;
           sockets.erase(ds->remote);
           break;
         }
@@ -608,6 +615,7 @@ void* tcpAcceptorThread(void* p)
         --g_tcpclientthreads->d_queued;
         close(ci->fd);
         delete ci;
+        ci=nullptr;
       }
     }
     catch(std::exception& e) {
diff --git a/pdns/misc.cc b/pdns/misc.cc
index e4eb2d58a9..1b7a545b13 100644
--- a/pdns/misc.cc
+++ b/pdns/misc.cc
@@ -1063,6 +1063,12 @@ bool setBlocking(int sock)
   return true;
 }
 
+bool isNonBlocking(int sock)
+{
+  int flags=fcntl(sock,F_GETFL,0);
+  return flags & O_NONBLOCK;
+}
+
 // Closes a socket.
 int closesocket( int socket )
 {
diff --git a/pdns/misc.hh b/pdns/misc.hh
index d9e6f9f8c4..7b2713fbf5 100644
--- a/pdns/misc.hh
+++ b/pdns/misc.hh
@@ -600,6 +600,7 @@ bool setBlocking( int sock );
 
 //! Sets the socket into non-blocking mode.
 bool setNonBlocking( int sock );
+bool isNonBlocking(int sock);
 int closesocket(int fd);
 bool setCloseOnExec(int sock);
 uint64_t udpErrorStats(const std::string& str);