Add ability to set and get DSCP socket option

tests/test_diffserv.cpp

@@ -0,0 +1,70 @@
+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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 "testutil.hpp"
+
+int main (void)
+{
+    int rc;
+    int tos = 0x28;
+    int o_tos;
+    size_t tos_size = sizeof(tos);
+
+    setup_test_environment();
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+
+    void *sb = zmq_socket (ctx, ZMQ_PAIR);
+    assert (sb);
+    rc = zmq_setsockopt (sb, ZMQ_TOS, &tos, tos_size);
+    assert (rc == 0);
+    rc = zmq_bind (sb, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+    rc = zmq_getsockopt (sb, ZMQ_TOS, &o_tos, &tos_size);
+    assert (rc == 0);
+    assert (o_tos == tos);
+
+    void *sc = zmq_socket (ctx, ZMQ_PAIR);
+    assert (sc);
+    tos = 0x58;
+    rc = zmq_setsockopt (sc, ZMQ_TOS, &tos, tos_size);
+    assert (rc == 0);
+    rc = zmq_connect (sc, "tcp://127.0.0.1:5560");
+    assert (rc == 0);
+    rc = zmq_getsockopt (sc, ZMQ_TOS, &o_tos, &tos_size);
+    assert (rc == 0);
+    assert (o_tos == tos);
+
+    // Wireshark can be used to verify that the server socket is
+    // using DSCP 0x28 in packets to the client while the client
+    // is using 0x58 in packets to the server.
+    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);
+
+    return 0 ;
+
+}