ZMQII-3: cheap and nasty implementation of message filtering

src/sub.cpp

@@ -0,0 +1,82 @@
+/*
+    Copyright (c) 2007-2009 FastMQ Inc.
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the Lesser GNU 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
+    Lesser GNU General Public License for more details.
+
+    You should have received a copy of the Lesser GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "../c/zmq.h"
+
+#include "sub.hpp"
+#include "err.hpp"
+
+zmq::sub_t::sub_t (class app_thread_t *parent_) :
+    socket_base_t (parent_)
+{
+}
+
+zmq::sub_t::~sub_t ()
+{
+}
+
+int zmq::sub_t::setsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ == ZMQ_SUBSCRIBE) {
+        std::string subscription ((const char*) optval_, optvallen_);
+        subscriptions.insert (subscription);
+        return 0;
+    }
+    
+    if (option_ == ZMQ_UNSUBSCRIBE) {
+        std::string subscription ((const char*) optval_, optvallen_);
+        subscriptions_t::iterator it = subscriptions.find (subscription);
+        if (it == subscriptions.end ()) {
+            errno = EINVAL;
+            return -1;
+        }
+        subscriptions.erase (it);
+        return 0;
+    }
+
+    return socket_base_t::setsockopt (option_, optval_, optvallen_);
+}
+
+int zmq::sub_t::recv (struct zmq_msg_t *msg_, int flags_)
+{
+    while (true) {
+
+        //  Get a message.
+        int rc = socket_base_t::recv (msg_, flags_);
+
+        //  If there's no message available, return immediately.
+        if (rc != 0 && errno == EAGAIN)
+            return -1;
+
+        //  Check the message format.
+        //  TODO: We should either ignore the message or drop the connection
+        //  if the message doesn't conform with the expected format.
+        unsigned char *data = (unsigned char*) zmq_msg_data (msg_);
+        zmq_assert (*data <= zmq_msg_size (msg_) - 1);
+
+        //  Check whether the message matches at least one subscription.
+        std::string topic ((const char*) (data + 1), *data);
+        subscriptions_t::iterator it = subscriptions.find (topic);
+        if (it != subscriptions.end ())
+            break;
+    }
+
+    return 0;
+}