[WIP] UDP supportudp

Signed-off-by: Martin Lucina <martin@lucina.net>

10 files changed, 744 insertions, 3 deletions

diff --git a/.gitignore b/.gitignore
index cbe01b4..95036b3 100755
--- a/.gitignore
+++ b/.gitignore
@@ -33,6 +33,7 @@ tests/pair_tcp
 tests/reqrep_inproc
 tests/reqrep_ipc
 tests/reqrep_tcp
+tests/pubsub_udp
 tests/shutdown_stress
 tests/hwm
 tests/timeo
diff --git a/src/Makefile.am b/src/Makefile.am
index 033ba52..33647b5 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -77,6 +77,8 @@ libxs_la_SOURCES = \
     tcp_connecter.hpp \
     tcp_listener.hpp \
     thread.hpp \
+    udp_receiver.hpp \
+    udp_sender.hpp \
     upoll.hpp \
     windows.hpp \
     wire.hpp \
@@ -136,6 +138,8 @@ libxs_la_SOURCES = \
     tcp_connecter.cpp \
     tcp_listener.cpp \
     thread.cpp \
+    udp_receiver.cpp \
+    udp_sender.cpp \
     upoll.cpp \
     xpub.cpp \
     xrep.cpp \
diff --git a/src/session_base.cpp b/src/session_base.cpp
index da9ee8e..f8a1cd1 100644
--- a/src/session_base.cpp
+++ b/src/session_base.cpp
@@ -30,6 +30,8 @@
 #include "ipc_connecter.hpp"
 #include "pgm_sender.hpp"
 #include "pgm_receiver.hpp"
+#include "udp_sender.hpp"
+#include "udp_receiver.hpp"
 
 #include "req.hpp"
 #include "xreq.hpp"
@@ -484,6 +486,42 @@ void xs::session_base_t::start_connecting (bool wait_)
     }
 #endif
 
+    //  UDP support.
+    if (protocol == "udp") {
+
+        //  At this point we'll create message pipes to the session straight
+        //  away. There's no point in delaying it as no concept of 'connect'
+        //  exists with UDP anyway.
+        if (options.type == XS_PUB || options.type == XS_XPUB) {
+
+            //  UDP sender.
+            udp_sender_t *udp_sender =  new (std::nothrow) udp_sender_t (
+                io_thread, options);
+            alloc_assert (udp_sender);
+
+            int rc = udp_sender->init (address.c_str ());
+            xs_assert (rc == 0);
+
+            send_attach (this, udp_sender);
+        }
+        else if (options.type == XS_SUB || options.type == XS_XSUB) {
+
+            //  UDP receiver.
+            udp_receiver_t *udp_receiver =  new (std::nothrow) udp_receiver_t (
+                io_thread, options);
+            alloc_assert (udp_receiver);
+
+            int rc = udp_receiver->init (address.c_str ());
+            xs_assert (rc == 0);
+
+            send_attach (this, udp_receiver);
+        }
+        else
+            xs_assert (false);
+
+        return;
+    }
+
     xs_assert (false);
 }
 
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index 960bd2c..2442e72 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -208,7 +208,7 @@ int xs::socket_base_t::check_protocol (const std::string &protocol_)
 {
     //  First check out whether the protcol is something we are aware of.
     if (protocol_ != "inproc" && protocol_ != "ipc" && protocol_ != "tcp" &&
-          protocol_ != "pgm" && protocol_ != "epgm") {
+          protocol_ != "pgm" && protocol_ != "epgm" && protocol_ != "udp") {
         errno = EPROTONOSUPPORT;
         return -1;
     }
@@ -234,7 +234,7 @@ int xs::socket_base_t::check_protocol (const std::string &protocol_)
     //  Check whether socket type and transport protocol match.
     //  Specifically, multicast protocols can't be combined with
     //  bi-directional messaging patterns (socket types).
-    if ((protocol_ == "pgm" || protocol_ == "epgm") &&
+    if ((protocol_ == "pgm" || protocol_ == "epgm" || protocol_ == "udp") &&
           options.type != XS_PUB && options.type != XS_SUB &&
           options.type != XS_XPUB && options.type != XS_XSUB) {
         errno = ENOCOMPATPROTO;
@@ -359,7 +359,7 @@ int xs::socket_base_t::bind (const char *addr_)
         return 0;
     }
 
-    if (protocol == "pgm" || protocol == "epgm") {
+    if (protocol == "pgm" || protocol == "epgm" || protocol == "udp") {
 
         //  For convenience's sake, bind can be used interchageable with
         //  connect for PGM and EPGM transports.
diff --git a/src/udp_receiver.cpp b/src/udp_receiver.cpp
new file mode 100644
index 0000000..9cd3c4c
--- /dev/null
+++ b/src/udp_receiver.cpp
@@ -0,0 +1,211 @@
+/*
+    Copyright (c) 2012 Martin Lucina <martin@lucina.net>
+
+    This file is part of Crossroads I/O.
+
+    Crossroads I/O 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.
+
+    Crossroads I/O 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 "platform.hpp"
+
+#include <new>
+
+#include "udp_receiver.hpp"
+#include "session_base.hpp"
+#include "stdint.hpp"
+#include "wire.hpp"
+#include "err.hpp"
+#include "ip.hpp"
+
+xs::udp_receiver_t::udp_receiver_t (class io_thread_t *parent_,
+      const options_t &options_) :
+    io_object_t (parent_),
+    options (options_),
+    pending_bytes (0),
+    pending_p (NULL),
+    session (NULL),
+    last_seq_no (0)
+{
+    decoder = new (std::nothrow) decoder_t (in_batch_size, options.maxmsgsize);
+    alloc_assert (decoder);
+}
+
+xs::udp_receiver_t::~udp_receiver_t ()
+{
+    delete decoder;
+}
+
+int xs::udp_receiver_t::init (const char *address_)
+{
+    int rc;
+
+    rc = address_resolve_tcp (&address, address_, false, options.ipv4only);
+    if (rc != 0)
+        return rc;
+
+    //  Create a unconnected UDP socket, bind it to the requested address
+    //  and make it non-blocking.
+    socket = open_socket (address.ss_family, SOCK_DGRAM, IPPROTO_UDP);
+    if (socket == -1)
+        return -1;
+    rc = ::bind (socket, (const sockaddr *)&address, address_size (&address));
+    if (rc != 0)
+        return -1;
+    unblock_socket (socket);
+
+    return 0;
+}
+
+void xs::udp_receiver_t::plug (io_thread_t *io_thread_,
+    session_base_t *session_)
+{
+    //  Start polling.
+    socket_handle = add_fd (socket);
+    set_pollin (socket_handle);
+
+    session = session_;
+    decoder->set_session (session);
+
+    //  If there are any subscriptions already queued in the session, drop them.
+    drop_subscriptions ();
+}
+
+void xs::udp_receiver_t::unplug ()
+{
+    rm_fd (socket_handle);
+
+    session = NULL;
+}
+
+void xs::udp_receiver_t::terminate ()
+{
+    unplug ();
+    delete this;
+}
+
+//  Called when our pipe is reactivated (has more data for us).
+void xs::udp_receiver_t::activate_out ()
+{
+    drop_subscriptions ();
+}
+
+//  Called when our pipe is reactivated (able to accept more data).
+void xs::udp_receiver_t::activate_in ()
+{
+    //  Process any pending data.
+    if (pending_bytes > 0) {
+        ssize_t processed_bytes = \
+            decoder->process_buffer (pending_p, pending_bytes);
+        //  Flush any messages produced by the decoder to the pipe.
+        session->flush ();
+        if (processed_bytes < pending_bytes) {
+            //  Some data (still) could not be written to the pipe.
+            pending_bytes -= processed_bytes;
+            pending_p += processed_bytes;
+            //  Try again later.
+            return;
+        }
+        //  Done with unprocessed data.
+        pending_bytes = 0;
+    }
+
+    //  Reactivate polling.
+    set_pollin (socket_handle);
+
+    //  Read any data that might have showed up on the socket in the mean time.
+    in_event (retired_fd);
+}
+
+//  Called when POLLIN is fired on the socket.
+void xs::udp_receiver_t::in_event (fd_t fd_)
+{
+    //  Receive a packet.
+    ssize_t recv_bytes = recv (socket, data, sizeof data, 0);
+    //  At the moment, go back to polling on EAGAIN and assert on any
+    //  other error.
+    if ((recv_bytes < 0) && errno == EAGAIN)
+        return;
+    assert (recv_bytes > 0);
+
+    //  Parse UDP packet header.
+    unsigned char *data_p = data;
+    uint32_t seq_no = get_uint32 (data_p);
+    uint16_t offset = get_uint16 (data_p + 4);
+    data_p += udp_header_size;
+    recv_bytes -= udp_header_size;
+
+    //  If this is our first packet, join the message stream.
+    if (last_seq_no == 0) {
+        if (offset == 0xffff)
+            return;
+        else {
+            data_p += offset;
+            recv_bytes -= offset;
+        }
+    }
+    //  Otherwise, decide based on the sequence number.
+    else {
+        //  If this packet is in sequence, process the whole packet.
+        if ((last_seq_no + 1) == seq_no)
+            ;
+        //  Otherwise, if it is an old packet, drop it.
+        else if (seq_no <= last_seq_no)
+            return;
+        //  Otherwise we have packet loss, rejoin the message stream.
+        else {
+            if (offset == 0xffff)
+                return;
+            else {
+                data_p += offset;
+                recv_bytes -= offset;
+
+                //  Re-create decoder to clear state.
+                delete decoder;
+                decoder = NULL;
+                decoder = new (std::nothrow) decoder_t (in_batch_size,
+                    options.maxmsgsize);
+                alloc_assert (decoder);
+                decoder->set_session (session);
+            }
+        }
+    }
+    //  If we get here, we will process this packet and it becomes our
+    //  last seen sequence number.
+    last_seq_no = seq_no;
+
+    //  Decode data and push it to our pipe.
+    ssize_t processed_bytes = decoder->process_buffer (data_p, recv_bytes);
+    if (processed_bytes < recv_bytes) {
+        //  Some data could not be written to the pipe. Save it for later.
+        pending_bytes = recv_bytes - processed_bytes;
+        pending_p = data_p + processed_bytes;
+        //  Stop polling. We will be restarted by a call to activate_in ().
+        reset_pollin (socket_handle);
+    }
+
+    //  Flush any messages produced by the decoder to the pipe.
+    session->flush ();
+}
+
+void xs::udp_receiver_t::out_event (fd_t fd_)
+{
+    assert (false);
+}
+
+void xs::udp_receiver_t::drop_subscriptions ()
+{
+    msg_t msg;
+    while (session->read (&msg))
+        msg.close ();
+}
diff --git a/src/udp_receiver.hpp b/src/udp_receiver.hpp
new file mode 100644
index 0000000..114df24
--- /dev/null
+++ b/src/udp_receiver.hpp
@@ -0,0 +1,101 @@
+/*
+    Copyright (c) 2012 Martin Lucina <martin@lucina.net>
+
+    This file is part of Crossroads I/O.
+
+    Crossroads I/O 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.
+
+    Crossroads I/O 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/>.
+*/
+
+#ifndef __XS_UDP_RECEIVER_HPP_INCLUDED__
+#define __XS_UDP_RECEIVER_HPP_INCLUDED__
+
+#include "platform.hpp"
+
+#include "io_object.hpp"
+#include "i_engine.hpp"
+#include "options.hpp"
+#include "decoder.hpp"
+#include "address.hpp"
+
+namespace xs
+{
+
+    class io_thread_t;
+    class session_base_t;
+
+    class udp_receiver_t : public io_object_t, public i_engine
+    {
+
+    public:
+
+        udp_receiver_t (xs::io_thread_t *parent_, const options_t &options_);
+        ~udp_receiver_t ();
+
+        int init (const char *address_);
+
+        //  i_engine interface implementation.
+        void plug (xs::io_thread_t *io_thread_,
+            xs::session_base_t *session_);
+        void unplug ();
+        void terminate ();
+        void activate_in ();
+        void activate_out ();
+
+        //  i_poll_events interface implementation.
+        void in_event (fd_t fd_);
+        void out_event (fd_t fd_);
+
+    private:
+
+        //  We don't support forwarding subscriptions upstream (yet).
+        void drop_subscriptions ();
+
+        //  Underlying UDP socket.
+        fd_t socket;
+        handle_t socket_handle;
+
+        //  Socket address.
+        address_t address;
+
+        //  Socket options.
+        options_t options;
+
+        //  Decoder for this socket.
+        decoder_t *decoder;
+
+        //  Amount of unprocessed data waiting in decoder, if any.
+        ssize_t pending_bytes;
+
+        //  Pointer to unprocessed data in buffer, if any.
+        unsigned char *pending_p;
+
+        //  Buffer for data to process.
+        unsigned char data [pgm_max_tpdu];
+
+        //  Associated session.
+        xs::session_base_t *session;
+
+        //  UDP header size.
+        static const size_t udp_header_size = 6;
+
+        //  Last sequence number seen, 0 if none.
+        uint32_t last_seq_no;
+
+        udp_receiver_t (const udp_receiver_t&);
+        const udp_receiver_t &operator = (const udp_receiver_t&);
+    };
+
+}
+
+#endif
diff --git a/src/udp_sender.cpp b/src/udp_sender.cpp
new file mode 100644
index 0000000..ddcffbb
--- /dev/null
+++ b/src/udp_sender.cpp
@@ -0,0 +1,197 @@
+/*
+    Copyright (c) 2012 Martin Lucina <martin@lucina.net>
+
+    This file is part of Crossroads I/O.
+
+    Crossroads I/O 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.
+
+    Crossroads I/O 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 "platform.hpp"
+
+#include <stdlib.h>
+
+#include "io_thread.hpp"
+#include "udp_sender.hpp"
+#include "session_base.hpp"
+#include "err.hpp"
+#include "wire.hpp"
+#include "stdint.hpp"
+#include "ip.hpp"
+
+xs::udp_sender_t::udp_sender_t (io_thread_t *parent_,
+      const options_t &options_) :
+    io_object_t (parent_),
+    options (options_),
+    encoder (0),
+    seq_no (1),
+    backoff_timer (NULL)
+{
+}
+
+xs::udp_sender_t::~udp_sender_t ()
+{
+    if (backoff_timer) {
+        rm_timer (backoff_timer);
+    }
+}
+
+int xs::udp_sender_t::init (const char *address_)
+{
+    int rc;
+
+    rc = address_resolve_tcp (&address, address_, false, options.ipv4only);
+    if (rc != 0)
+        return rc;
+
+    //  Create a connected UDP socket for a single peer, and make
+    //  it non-blocking.
+    socket = open_socket (address.ss_family, SOCK_DGRAM, IPPROTO_UDP);
+    if (socket == -1)
+        return -1;
+    rc = ::connect (socket, (const sockaddr *)&address,
+        address_size (&address));
+    if (rc != 0)
+        return -1;
+    unblock_socket (socket);
+
+    return 0;
+}
+
+void xs::udp_sender_t::plug (io_thread_t *io_thread_, session_base_t *session_)
+{
+    session = session_;
+    encoder.set_session (session);
+
+    //  Start polling.
+    socket_handle = add_fd (socket);
+    set_pollout (socket_handle);
+
+    //  UDP cannot pass subscriptions upstream; for now just fake subscribing
+    //  to all messages.
+    msg_t msg;
+    msg.init_size (1);
+    *(unsigned char*) msg.data () = 1;
+    int rc = session_->write (&msg);
+    errno_assert (rc == 0);
+    session_->flush ();
+}
+
+void xs::udp_sender_t::unplug ()
+{
+    rm_fd (socket_handle);
+
+    session = NULL;
+}
+
+void xs::udp_sender_t::terminate ()
+{
+    unplug ();
+    delete this;
+}
+
+//  Called when our pipe is reactivated (has more data for us).
+void xs::udp_sender_t::activate_out ()
+{
+    //  Reactivate polling.
+    set_pollout (socket_handle);
+    //  Try and send more data.
+    out_event (retired_fd);
+}
+
+void xs::udp_sender_t::activate_in ()
+{
+    xs_assert (false);
+}
+
+//  Called when POLLERR is fired on the socket.
+void xs::udp_sender_t::in_event (fd_t fd_)
+{
+    //  Get the actual error code from the socket.
+    int err = 0;
+    socklen_t len = sizeof (err);
+    int rc = getsockopt (socket, SOL_SOCKET, SO_ERROR, (char *) &err, &len);
+    errno_assert (rc == 0);
+
+    //  If we got ECONNREFUSED, there is no one on the other end.
+    //  Stop sending for XS_RECONNECT_IVL milliseconds.
+    if (err == ECONNREFUSED) {
+        backoff_timer = add_timer (options.reconnect_ivl);
+        //  Polling will be re-started by timer_event ().
+        reset_pollout (socket_handle);
+        return;
+    }
+
+    //  Any other error is a bug, for now.
+    errno = err;
+    errno_assert (false);
+}
+
+//  Called when POLLOUT is fired on the socket.
+void xs::udp_sender_t::out_event (fd_t fd_)
+{
+    unsigned char *data_p = data;
+    size_t size = pgm_max_tpdu - udp_header_size;
+    int offset = 0;
+
+    //  Get one packet of data from the encoder.
+    encoder.get_data (&data_p, &size, &offset);
+    //  If there is no data in the pipe
+    if (size == 0) {
+        //  Stop polling, we will be re-started by activate_out ().
+        reset_pollout (socket_handle);
+        return;
+    }
+    assert ((size + udp_header_size) <= pgm_max_tpdu);
+
+    //  Prepare UDP header (seqno, offset).
+    unsigned char udp_header [udp_header_size];
+    put_uint32 (udp_header, seq_no);
+    put_uint16 (udp_header + 4, (uint16_t) offset);
+
+    //  Send out the message, ensuring the whole message was sent.
+    struct iovec iov[2] = {
+        { udp_header, udp_header_size },
+        { data_p, size }
+    };
+    ssize_t write_bytes = writev (socket, iov, 2);
+
+    //  If we got ECONNREFUSED, there is no one on the other end.
+    //  Drop the packet and back off for XS_RECONNECT_IVL milliseconds.
+    if (write_bytes == -1 && errno == ECONNREFUSED) {
+        backoff_timer = add_timer (options.reconnect_ivl);
+        //  Polling will be re-started by timer_event ().
+        reset_pollout (socket_handle);
+        //  Increase sequence number to ensure other end is notified of
+        //  dropped packet.
+        ++seq_no;
+        return;
+    }
+    errno_assert (write_bytes > 0);
+    assert ((size_t)write_bytes == (udp_header_size + size));
+
+    //  Packet was sent successfully, increase sequence number.
+    ++seq_no;
+}
+
+//  Called when our backoff timer expires.
+void xs::udp_sender_t::timer_event (handle_t handle_)
+{
+    xs_assert (handle_ == backoff_timer);
+    backoff_timer = NULL;
+
+    //  Re-start polling.
+    set_pollout (socket_handle);
+
+    out_event (retired_fd);
+}
diff --git a/src/udp_sender.hpp b/src/udp_sender.hpp
new file mode 100644
index 0000000..e7c2472
--- /dev/null
+++ b/src/udp_sender.hpp
@@ -0,0 +1,97 @@
+/*
+    Copyright (c) 2012 Martin Lucina <martin@lucina.net>
+
+    This file is part of Crossroads I/O.
+
+    Crossroads I/O 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.
+
+    Crossroads I/O 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/>.
+*/
+
+#ifndef __XS_UDP_SENDER_HPP_INCLUDED__
+#define __XS_UDP_SENDER_HPP_INCLUDED__
+
+#include "platform.hpp"
+
+#include "stdint.hpp"
+#include "io_object.hpp"
+#include "i_engine.hpp"
+#include "options.hpp"
+#include "address.hpp"
+#include "encoder.hpp"
+
+namespace xs
+{
+
+    class io_thread_t;
+    class session_base_t;
+
+    class udp_sender_t : public io_object_t, public i_engine
+    {
+
+    public:
+
+        udp_sender_t (xs::io_thread_t *parent_, const options_t &options_);
+        ~udp_sender_t ();
+
+        int init (const char *address_);
+
+        //  i_engine interface implementation.
+        void plug (xs::io_thread_t *io_thread_,
+            xs::session_base_t *session_);
+        void unplug ();
+        void terminate ();
+        void activate_in ();
+        void activate_out ();
+
+        //  i_poll_events interface implementation.
+        void in_event (fd_t fd_);
+        void out_event (fd_t fd_);
+        void timer_event (handle_t handle_);
+
+    private:
+
+        //  Underlying UDP socket.
+        fd_t socket;
+        handle_t socket_handle;
+
+        //  Socket address.
+        address_t address;
+
+        //  Socket options.
+        options_t options;
+
+        //  Encoder for this socket.
+        encoder_t encoder;
+
+        //  Associated session.
+        xs::session_base_t *session;
+
+        //  UDP packet header size.
+        static const size_t udp_header_size = 6;
+
+        //  Packet buffer for outgoing packets.
+        unsigned char data [pgm_max_tpdu];
+
+        //  Sequence number for outgoing packets.
+        uint32_t seq_no;
+
+        //  Backoff timer if receiver is not present.
+        handle_t backoff_timer;
+
+        udp_sender_t (const udp_sender_t&);
+        const udp_sender_t &operator = (const udp_sender_t&);
+    };
+
+}
+
+#endif
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 27ca5dd..52e8e1c 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -7,6 +7,7 @@ noinst_PROGRAMS = pair_inproc \
                   pair_tcp \
                   reqrep_inproc \
                   reqrep_tcp \
+                  pubsub_udp \
                   hwm \
                   reqrep_device \
                   sub_forward \
@@ -32,6 +33,7 @@ pair_inproc_SOURCES = pair_inproc.cpp testutil.hpp
 pair_tcp_SOURCES = pair_tcp.cpp testutil.hpp
 reqrep_inproc_SOURCES = reqrep_inproc.cpp testutil.hpp
 reqrep_tcp_SOURCES = reqrep_tcp.cpp testutil.hpp
+pubsub_udp_SOURCES = pubsub_udp.cpp testutil.hpp
 hwm_SOURCES = hwm.cpp
 reqrep_device_SOURCES = reqrep_device.cpp
 sub_forward_SOURCES = sub_forward.cpp
diff --git a/tests/pubsub_udp.cpp b/tests/pubsub_udp.cpp
new file mode 100644
index 0000000..e981457
--- /dev/null
+++ b/tests/pubsub_udp.cpp
@@ -0,0 +1,90 @@
+/*
+    Copyright (c) 2012 Martin Lucina <martin@lucina.net>
+
+    This file is part of Crossroads I/O.
+
+    Crossroads I/O 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.
+
+    Crossroads I/O 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 XS_TEST_MAIN ()
+{
+    fprintf (stderr, "pubsub_udp test running...\n");
+
+    void *ctx = xs_init ();
+    assert (ctx);
+
+    void *pub = xs_socket (ctx, XS_PUB);
+    assert (pub);
+    int rc = xs_bind (pub, "udp://127.0.0.1:5555");
+    assert (rc != -1);
+
+    void *sub = xs_socket (ctx, XS_SUB);
+    assert (sub);
+    rc = xs_connect (sub, "udp://127.0.0.1:5555");
+    assert (rc != -1);
+    rc = xs_setsockopt (sub, XS_SUBSCRIBE, "", 0);
+    assert (rc == 0);
+    
+    const char *content = "12345678ABCDEFGH12345678abcdefgh";
+
+    //  TODO: Due to a core bug, the first message on a PUB/SUB socket
+    //  is always lost. For now just send a dummy message.
+    rc = xs_send (pub, "", 0, 0);
+    assert (rc == 0);
+
+    //  Send a message with two identical parts.
+    rc = xs_send (pub, content, 32, XS_SNDMORE);
+    assert (rc == 32);
+    rc = xs_send (pub, content, 32, 0);
+    assert (rc == 32);
+    
+    //  Receive the first part.
+    char rcvbuf [32];
+    int rcvmore = 0;
+    size_t rcvmore_sz = sizeof rcvmore;
+    rc = xs_recv (sub, rcvbuf, 32, 0);
+    assert (rc == 32);
+    rc = xs_getsockopt (sub, XS_RCVMORE, &rcvmore, &rcvmore_sz);
+    assert (rc == 0);
+
+    //  There must be one more part to receive.
+    assert (rcvmore);
+    //  And the content must match what was sent.
+    assert (memcmp (rcvbuf, content, 32) == 0);
+
+    //  Receive the second part.
+    rc = xs_recv (sub, rcvbuf, 32, 0);
+    assert (rc == 32);
+    rcvmore_sz = sizeof rcvmore;
+    rc = xs_getsockopt (sub, XS_RCVMORE, &rcvmore, &rcvmore_sz);
+    assert (rc == 0);
+
+    //  There must not be another part.
+    assert (!rcvmore);
+    //  And the content must match what was sent.
+    assert (memcmp (rcvbuf, content, 32) == 0);
+
+    rc = xs_close (pub);
+    assert (rc == 0);
+
+    rc = xs_close (sub);
+    assert (rc == 0);
+
+    rc = xs_term (ctx);
+    assert (rc == 0);
+
+    return 0 ;
+}