prevent SIGPIPE from being generated

src/lib/ares__socket.c

@@ -186,6 +186,14 @@ static int configure_socket(ares_socket_t s, struct server_state *server)
   }
 #endif
 
+  /* No need to emit SIGPIPE on socket errors */
+#if defined(SO_NOSIGPIPE)
+  {
+    int opt = 1;
+    setsockopt(s, SOL_SOCKET, SO_NOSIGPIPE, (void *)&opt, sizeof(opt));
+  }
+#endif
+
   /* Set the socket's send and receive buffer sizes. */
   if ((channel->socket_send_buffer_size > 0) &&
       setsockopt(s, SOL_SOCKET, SO_SNDBUF,

test/ares-test.cc

@@ -431,10 +431,16 @@ MockServer::MockServer(int family, unsigned short port)
   // Send TCP data right away.
   setsockopt(tcpfd_, IPPROTO_TCP, TCP_NODELAY,
              BYTE_CAST &optval , sizeof(int));
+#if defined(SO_NOSIGPIPE)
+  setsockopt(tcpfd_, SOL_SOCKET, SO_NOSIGPIPE, (void *)&optval, sizeof(optval));
+#endif
 
   // Create a UDP socket to receive data on.
   udpfd_ = socket(family, SOCK_DGRAM, 0);
   EXPECT_NE(ARES_SOCKET_BAD, udpfd_);
+#if defined(SO_NOSIGPIPE)
+  setsockopt(udpfd_, SOL_SOCKET, SO_NOSIGPIPE, (void *)&optval, sizeof(optval));
+#endif
 
   // Bind the sockets to the given port.
   if (family == AF_INET) {
@@ -655,6 +661,8 @@ std::set<ares_socket_t> MockServer::fds() const {
 void MockServer::ProcessRequest(ares_socket_t fd, struct sockaddr_storage* addr,
                                 ares_socklen_t addrlen, const std::string &reqstr,
                                 int qid, const std::string& name, int rrtype) {
+  int flags = 0;
+
   // Before processing, let gMock know the request is happening.
   OnRequest(name, rrtype);
 
@@ -695,7 +703,11 @@ void MockServer::ProcessRequest(ares_socket_t fd, struct sockaddr_storage* addr,
     addrlen = 0;
   }
 
-  ares_ssize_t rc = (ares_ssize_t)sendto(fd, BYTE_CAST reply.data(), (SEND_TYPE_ARG3)reply.size(), 0,
+#ifdef MSG_NOSIGNAL
+  flags |= MSG_NOSIGNAL;
+#endif
+
+  ares_ssize_t rc = (ares_ssize_t)sendto(fd, BYTE_CAST reply.data(), (SEND_TYPE_ARG3)reply.size(), flags,
                   (struct sockaddr *)addr, addrlen);
   if (rc < static_cast<ares_ssize_t>(reply.size())) {
     std::cerr << "Failed to send full reply, rc=" << rc << std::endl;