Merge pull request #71 from jagerman/disable-ipv6

Disable IPv6 by default

CMakeLists.txt

@@ -17,7 +17,7 @@ cmake_minimum_required(VERSION 3.7)
 set(CMAKE_OSX_DEPLOYMENT_TARGET 10.12 CACHE STRING "macOS deployment target (Apple clang only)")
 
 project(liboxenmq
-    VERSION 1.2.9
+    VERSION 1.2.10
     LANGUAGES CXX C)
 
 include(GNUInstallDirs)

oxenmq/connections.cpp

@@ -40,7 +40,9 @@ void OxenMQ::setup_external_socket(zmq::socket_t& socket) {
     socket.set(zmq::sockopt::reconnect_ivl_max, (int) RECONNECT_INTERVAL_MAX.count());
     socket.set(zmq::sockopt::handshake_ivl, (int) HANDSHAKE_TIME.count());
     socket.set(zmq::sockopt::maxmsgsize, MAX_MSG_SIZE);
-    socket.set(zmq::sockopt::ipv6, 1);
+    if (IPV6)
+        socket.set(zmq::sockopt::ipv6, 1);
+
     if (CONN_HEARTBEAT > 0s) {
         socket.set(zmq::sockopt::heartbeat_ivl, (int) CONN_HEARTBEAT.count());
         if (CONN_HEARTBEAT_TIMEOUT > 0s)

oxenmq/oxenmq.h

@@ -296,6 +296,15 @@ public:
      */
     int SOCKET_UID = -1;
 
+    /** If true then enable IPv6 connectivity on incoming/outgoing sockets.  This is disabled by
+     * default because enabling it in libzmq breaks IPv4-only clients trying to connect to
+     * dual-stack IPv6+IPv4 hosts by hostname (the client will *only* try IPv6 if it finds an IPv6
+     * address, even if it has no IPv6 connectivity).
+     *
+     * This only has an effect for sockets created *after* it is changed.
+     */
+    bool IPV6 = false;
+
     /// A special TaggedThreadID value that always refers to the proxy thread; the main use of this is
     /// to direct very simple batch completion jobs to be executed directly in the proxy thread.
     inline static constexpr TaggedThreadID run_in_proxy{-1};