udp.cpp

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/*
 * Copyright 2013,2014 Vladimir Ermakov.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <cassert>
#include <console_bridge/console.h>

#include <mavconn/thread_utils.h>
#include <mavconn/udp.h>

namespace mavconn {
using boost::system::error_code;
using boost::asio::io_service;
using boost::asio::ip::udp;
using boost::asio::buffer;
using mavutils::to_string_cs;
typedef std::lock_guard<std::recursive_mutex> lock_guard;


static bool resolve_address_udp(io_service &io, std::string host, unsigned short port, udp::endpoint &ep)
{
        bool result = false;
        udp::resolver resolver(io);
        error_code ec;

        udp::resolver::query query(host, "");
        std::for_each(resolver.resolve(query, ec), udp::resolver::iterator(),
                [&](const udp::endpoint &q_ep) {
                        ep = q_ep;
                        ep.port(port);
                        result = true;
                        logDebug("udp: host %s resolved as %s", host.c_str(), to_string_cs(ep));
                });

        if (ec) {
                logWarn("udp: resolve error: %s", ec.message().c_str());
                result = false;
        }

        return result;
}


MAVConnUDP::MAVConnUDP(uint8_t system_id, uint8_t component_id,
                std::string bind_host, unsigned short bind_port,
                std::string remote_host, unsigned short remote_port) :
        MAVConnInterface(system_id, component_id),
        remote_exists(false),
        tx_in_progress(false),
        io_service(),
        io_work(new io_service::work(io_service)),
        socket(io_service)
{
        if (!resolve_address_udp(io_service, bind_host, bind_port, bind_ep))
                throw DeviceError("udp: resolve", "Bind address resolve failed");

        logInform("udp%d: Bind address: %s", channel, to_string_cs(bind_ep));

        if (remote_host != "") {
                remote_exists = resolve_address_udp(io_service, remote_host, remote_port, remote_ep);

                if (remote_exists)
                        logInform("udp%d: Remote address: %s", channel, to_string_cs(remote_ep));
                else
                        logWarn("udp%d: Remote address resolve failed.", channel);
        }

        try {
                socket.open(udp::v4());
                socket.bind(bind_ep);
        }
        catch (boost::system::system_error &err) {
                throw DeviceError("udp", err);
        }

        // give some work to io_service before start
        io_service.post(boost::bind(&MAVConnUDP::do_recvfrom, this));

        // run io_service for async io
        std::thread t(boost::bind(&io_service::run, &this->io_service));
        mavutils::set_thread_name(t, "MAVConnUDP%d", channel);
        io_thread.swap(t);
}

MAVConnUDP::~MAVConnUDP() {
        close();
}

void MAVConnUDP::close() {
        lock_guard lock(mutex);
        if (!is_open())
                return;

        io_work.reset();
        io_service.stop();
        socket.close();

        // clear tx queue
        std::for_each(tx_q.begin(), tx_q.end(),
                        [](MsgBuffer *p) { delete p; });
        tx_q.clear();

        if (io_thread.joinable())
                io_thread.join();

        /* emit */ port_closed();
}

void MAVConnUDP::send_bytes(const uint8_t *bytes, size_t length)
{
        if (!is_open()) {
                logError("udp%d:send: channel closed!", channel);
                return;
        }

        if (!remote_exists) {
                logDebug("udp%d:send: Remote not known, message dropped.", channel);
                return;
        }

        MsgBuffer *buf = new MsgBuffer(bytes, length);
        {
                lock_guard lock(mutex);
                tx_q.push_back(buf);
        }
        io_service.post(boost::bind(&MAVConnUDP::do_sendto, this, true));
}

void MAVConnUDP::send_message(const mavlink_message_t *message, uint8_t sysid, uint8_t compid)
{
        assert(message != nullptr);

        if (!is_open()) {
                logError("udp%d:send: channel closed!", channel);
                return;
        }

        if (!remote_exists) {
                logDebug("udp%d:send: Remote not known, message dropped.", channel);
                return;
        }

        logDebug("udp%d:send: Message-Id: %d [%d bytes] Sys-Id: %d Comp-Id: %d",
                        channel, message->msgid, message->len, sysid, compid);

        MsgBuffer *buf = new_msgbuffer(message, sysid, compid);
        {
                lock_guard lock(mutex);
                tx_q.push_back(buf);
        }
        io_service.post(boost::bind(&MAVConnUDP::do_sendto, this, true));
}

void MAVConnUDP::do_recvfrom()
{
        socket.async_receive_from(
                        buffer(rx_buf, sizeof(rx_buf)),
                        remote_ep,
                        boost::bind(&MAVConnUDP::async_receive_end,
                                this,
                                boost::asio::placeholders::error,
                                boost::asio::placeholders::bytes_transferred));
}

void MAVConnUDP::async_receive_end(error_code error, size_t bytes_transferred)
{
        mavlink_message_t message;
        mavlink_status_t status;

        if (error) {
                logError("udp%d:receive: %s", channel, error.message().c_str());
                close();
                return;
        }

        if (remote_ep != last_remote_ep) {
                logInform("udp%d: Remote address: %s", channel, to_string_cs(remote_ep));
                remote_exists = true;
                last_remote_ep = remote_ep;
        }

        for (ssize_t i = 0; i < bytes_transferred; i++) {
                if (mavlink_parse_char(channel, rx_buf[i], &message, &status)) {
                        logDebug("udp%d:recv: Message-Id: %d [%d bytes] Sys-Id: %d Comp-Id: %d",
                                        channel, message.msgid, message.len, message.sysid, message.compid);

                        /* emit */ message_received(&message, message.sysid, message.compid);
                }
        }

        do_recvfrom();
}

void MAVConnUDP::do_sendto(bool check_tx_state)
{
        if (check_tx_state && tx_in_progress)
                return;

        lock_guard lock(mutex);
        if (tx_q.empty())
                return;

        tx_in_progress = true;
        MsgBuffer *buf = tx_q.front();
        socket.async_send_to(
                        buffer(buf->dpos(), buf->nbytes()),
                        remote_ep,
                        boost::bind(&MAVConnUDP::async_sendto_end,
                                this,
                                boost::asio::placeholders::error,
                                boost::asio::placeholders::bytes_transferred));
}

void MAVConnUDP::async_sendto_end(error_code error, size_t bytes_transferred)
{
        if (error) {
                logError("udp%d:sendto: %s", channel, error.message().c_str());
                close();
                return;
        }

        lock_guard lock(mutex);
        if (tx_q.empty()) {
                tx_in_progress = false;
                return;
        }

        MsgBuffer *buf = tx_q.front();
        buf->pos += bytes_transferred;
        if (buf->nbytes() == 0) {
                tx_q.pop_front();
                delete buf;
        }

        if (!tx_q.empty())
                do_sendto(false);
        else
                tx_in_progress = false;
}

}; // namespace mavconn