Problem: cannot use new pre-allocated FD with TCP

Solution: parse the value set by the ZMQ_PRE_ALLOCATED_FD sockopt
when creating a new TCP socket and use it if valid.
Add new tests/test_pre_allocated_fd_tcp.cpp unit test.

.gitignore

@@ -126,6 +126,7 @@ test_radio_dish
 test_udp
 test_large_msg
 test_pre_allocated_fd_ipc
+test_pre_allocated_fd_tcp
 tests/test*.log
 tests/test*.trs
 src/platform.hpp*

Makefile.am

@@ -618,6 +618,7 @@ test_apps += \
 	tests/test_pair_ipc \
 	tests/test_reqrep_ipc \
 	tests/test_pre_allocated_fd_ipc \
+	tests/test_pre_allocated_fd_tcp \
 	tests/test_timeo \
 	tests/test_filter_ipc
 
@@ -645,6 +646,11 @@ tests_test_pre_allocated_fd_ipc_SOURCES = \
 	tests/testutil.hpp
 tests_test_pre_allocated_fd_ipc_LDADD = src/libzmq.la
 
+tests_test_pre_allocated_fd_tcp_SOURCES = \
+	tests/test_pre_allocated_fd_tcp.cpp \
+	tests/testutil.hpp
+tests_test_pre_allocated_fd_tcp_LDADD = src/libzmq.la
+
 if HAVE_FORK
 test_apps += tests/test_fork
 

src/tcp_listener.cpp

@@ -166,6 +166,14 @@ int zmq::tcp_listener_t::set_address (const char *addr_)
     if (rc != 0)
         return -1;
 
+    address.to_string (endpoint);
+
+    if (options.pre_allocated_fd != -1) {
+        s = options.pre_allocated_fd;
+        socket->event_listening (endpoint, (int) s);
+        return 0;
+    }
+
     //  Create a listening socket.
     s = open_socket (address.family (), SOCK_STREAM, IPPROTO_TCP);
 #ifdef ZMQ_HAVE_WINDOWS
@@ -224,8 +232,6 @@ int zmq::tcp_listener_t::set_address (const char *addr_)
     errno_assert (rc == 0);
 #endif
 
-    address.to_string (endpoint);
-
     //  Bind the socket to the network interface and port.
     rc = bind (s, address.addr (), address.addrlen ());
 #ifdef ZMQ_HAVE_WINDOWS

tests/CMakeLists.txt

@@ -91,6 +91,7 @@ if(NOT WIN32)
           test_router_mandatory_hwm
           test_term_endpoint_tipc
           test_pre_allocated_fd_ipc
+          test_pre_allocated_fd_tcp
   )
   if(HAVE_FORK)
     list(APPEND tests test_fork)

tests/test_pre_allocated_fd_tcp.cpp

@@ -0,0 +1,206 @@
+/*
+    Copyright (c) 2016 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include "testutil.hpp"
+
+void pre_allocate_sock (void *zmq_socket, const char *address,
+        const char *port)
+{
+    struct addrinfo *addr;
+    int rc = getaddrinfo (address, port, NULL, &addr);
+    assert (rc == 0);
+
+    int s_pre = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
+    assert (s_pre != -1);
+
+    int flag = 1;
+    rc = setsockopt (s_pre, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof (int));
+    assert (rc == 0);
+
+    rc = bind (s_pre, addr->ai_addr, addr->ai_addrlen);
+    assert (rc == 0);
+
+    rc = listen (s_pre, SOMAXCONN);
+    assert (rc == 0);
+
+    rc = zmq_setsockopt (zmq_socket, ZMQ_PRE_ALLOCATED_FD, &s_pre,
+            sizeof (s_pre));
+    assert(rc == 0);
+}
+
+void test_req_rep ()
+{
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+
+    void *sb = zmq_socket (ctx, ZMQ_REP);
+    assert (sb);
+
+    pre_allocate_sock(sb, "127.0.0.1", "5560");
+
+    int rc = zmq_bind (sb, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    void *sc = zmq_socket (ctx, ZMQ_REQ);
+    assert (sc);
+    rc = zmq_connect (sc, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    bounce (sb, sc);
+
+    rc = zmq_close (sc);
+    assert (rc == 0);
+
+    rc = zmq_close (sb);
+    assert (rc == 0);
+
+    rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+}
+
+void test_pair ()
+{
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+
+    void *sb = zmq_socket (ctx, ZMQ_PAIR);
+    assert (sb);
+
+    pre_allocate_sock(sb, "127.0.0.1", "5560");
+
+    int rc = zmq_bind (sb, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    void *sc = zmq_socket (ctx, ZMQ_PAIR);
+    assert (sc);
+    rc = zmq_connect (sc, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    bounce (sb, sc);
+
+    rc = zmq_close (sc);
+    assert (rc == 0);
+
+    rc = zmq_close (sb);
+    assert (rc == 0);
+
+    rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+}
+
+void test_client_server ()
+{
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+
+    void *sb = zmq_socket (ctx, ZMQ_SERVER);
+    assert (sb);
+
+    pre_allocate_sock(sb, "127.0.0.1", "5560");
+
+    int rc = zmq_bind (sb, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    void *sc = zmq_socket (ctx, ZMQ_CLIENT);
+    assert (sc);
+    rc = zmq_connect (sc, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+
+    zmq_msg_t msg;
+    rc = zmq_msg_init_size (&msg, 1);
+    assert (rc == 0);
+
+    char *data = (char *) zmq_msg_data (&msg);
+    data [0] = 1;
+
+    rc = zmq_msg_send (&msg, sc, ZMQ_SNDMORE);
+    assert (rc == -1);
+
+    rc = zmq_msg_send (&msg, sc, 0);
+    assert (rc == 1);
+
+    rc = zmq_msg_init (&msg);
+    assert (rc == 0);
+
+    rc = zmq_msg_recv (&msg, sb, 0);
+    assert (rc == 1);
+
+    uint32_t routing_id = zmq_msg_routing_id (&msg);
+    assert (routing_id != 0);
+
+    rc = zmq_msg_close (&msg);
+    assert (rc == 0);
+
+    rc = zmq_msg_init_size (&msg, 1);
+    assert (rc == 0);
+
+    data = (char *)zmq_msg_data (&msg);
+    data[0] = 2;
+
+    rc = zmq_msg_set_routing_id (&msg, routing_id);
+    assert (rc == 0);
+
+    rc = zmq_msg_send (&msg, sb, ZMQ_SNDMORE);
+    assert (rc == -1);
+
+    rc = zmq_msg_send (&msg, sb, 0);
+    assert (rc == 1);
+
+    rc = zmq_msg_recv (&msg, sc, 0);
+    assert (rc == 1);
+
+    routing_id = zmq_msg_routing_id (&msg);
+    assert (routing_id == 0);
+
+    rc = zmq_msg_close (&msg);
+    assert (rc == 0);
+
+    rc = zmq_close (sc);
+    assert (rc == 0);
+
+    rc = zmq_close (sb);
+    assert (rc == 0);
+
+    rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+}
+
+int main (void)
+{
+    setup_test_environment();
+
+    test_req_rep();
+    test_pair();
+    test_client_server();
+
+    return 0 ;
+}