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/*
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 ();
}
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