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Diffstat (limited to 'src/udp_receiver.cpp')
| -rw-r--r-- | src/udp_receiver.cpp | 211 |
1 files changed, 211 insertions, 0 deletions
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 (); +} |