UDP support

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

1 files changed, 197 insertions, 0 deletions

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);
+}