ardupilot/libraries/AP_HAL_AVR_SITL/UARTDriver.cpp

// -*- Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
   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, see <http://www.gnu.org/licenses/>.
 */

//
//      Copyright (c) 2010 Michael Smith. All rights reserved.
//
#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_AVR_SITL

#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdarg.h>
#include <AP_Math.h>

#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>

#include "UARTDriver.h"
#include "SITL_State.h"

using namespace AVR_SITL;

// On OSX, MSG_NOSIGNAL doesn't exist. The equivalent is to set SO_NOSIGPIPE
// in setsockopt for the socket. However, if we just skip that, and don't use
// MSG_NOSIGNAL, everything seems to work fine and SIGPIPE doesn't seem to be
// generated.
#ifndef MSG_NOSIGNAL
#define MSG_NOSIGNAL 0
#endif

bool SITLUARTDriver::_console;

/* UARTDriver method implementations */

void SITLUARTDriver::begin(uint32_t baud, uint16_t rxSpace, uint16_t txSpace) 
{
    if (txSpace != 0) {
        _txSpace = txSpace;
    }
    if (rxSpace != 0) {
        _rxSpace = rxSpace;
    }
    switch (_portNumber) {
    case 0:
        _tcp_start_connection(true);
        break;

    case 1:
        /* gps */
        _connected = true;
        _fd = _sitlState->gps_pipe();
        break;
        
    default:
        _tcp_start_connection(false);
        break;
    }
}

void SITLUARTDriver::end() 
{
}

int16_t SITLUARTDriver::available(void) 
{
    _check_connection();

    if (!_connected) {
        return 0;
    }
    
    if (_select_check(_fd)) {
#ifdef FIONREAD
        // use FIONREAD to get exact value if possible
        int num_ready;
        if (ioctl(_fd, FIONREAD, &num_ready) == 0) {
            if (num_ready > _rxSpace) {
                return _rxSpace;
            }
            if (num_ready == 0) {
                // EOF is reached
                fprintf(stdout, "Closed connection on serial port %u\n", _portNumber);
                close(_fd);
                _connected = false;
                return 0;
            }
            return num_ready;
        }
#endif
        return 1; // best we can do is say 1 byte available
    }
    return 0;
}



int16_t SITLUARTDriver::txspace(void) 
{
    // always claim there is space available
    return _txSpace;
}

int16_t SITLUARTDriver::read(void) 
{
    char c;

    if (available() <= 0) {
        return -1;
    }

    if (_portNumber == 1) {
        if (_sitlState->gps_read(_fd, &c, 1) == 1) {
            return (uint8_t)c;
        }
        return -1;
    }

    if (_console) {
        return ::read(0, &c, 1);
    }

    int n = recv(_fd, &c, 1, MSG_DONTWAIT | MSG_NOSIGNAL);
    if (n <= 0) {
        // the socket has reached EOF
        close(_fd);
        _connected = false;
        fprintf(stdout, "Closed connection on serial port %u\n", _portNumber);
        fflush(stdout);
        return -1;
    }
    if (n == 1) {
        return (uint8_t)c;
    }
    return -1;
}

void SITLUARTDriver::flush(void) 
{
}

size_t SITLUARTDriver::write(uint8_t c) 
{
    int flags = MSG_NOSIGNAL;
    _check_connection();
    if (!_connected) {
        return 0;
    }
    if (_nonblocking_writes) {
        flags |= MSG_DONTWAIT;
    }
    if (_console) {
        return ::write(_fd, &c, 1);
    }
    return send(_fd, &c, 1, flags);
}

/*
  start a TCP connection for the serial port. If wait_for_connection
  is true then block until a client connects
 */
void SITLUARTDriver::_tcp_start_connection(bool wait_for_connection)
{
	int one=1;
	struct sockaddr_in sockaddr;
	int ret;

        if (_connected) {
            return;
        }

	if (_console) {
            // hack for console access
            _connected = true;
            _listen_fd = -1;
            _fd = 1;
            return;
	}

        if (_fd != -1) {
            close(_fd);
        }

        if (_listen_fd == -1) {
            memset(&sockaddr,0,sizeof(sockaddr));

#ifdef HAVE_SOCK_SIN_LEN
            sockaddr.sin_len = sizeof(sockaddr);
#endif
            sockaddr.sin_port = htons(_sitlState->base_port() + _portNumber);
            sockaddr.sin_family = AF_INET;

            _listen_fd = socket(AF_INET, SOCK_STREAM, 0);
            if (_listen_fd == -1) {
		fprintf(stderr, "socket failed - %s\n", strerror(errno));
		exit(1);
            }

            /* we want to be able to re-use ports quickly */
            setsockopt(_listen_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));

            fprintf(stderr, "bind port %u for %u\n", 
                    (unsigned)ntohs(sockaddr.sin_port),
                    (unsigned)_portNumber),

            ret = bind(_listen_fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));
            if (ret == -1) {
		fprintf(stderr, "bind failed on port %u - %s\n",
                        (unsigned)ntohs(sockaddr.sin_port),
                        strerror(errno));
		exit(1);
            }

            ret = listen(_listen_fd, 5);
            if (ret == -1) {
                fprintf(stderr, "listen failed - %s\n", strerror(errno));
                exit(1);
            }

            fprintf(stderr, "Serial port %u on TCP port %u\n", _portNumber, 
                    _sitlState->base_port() + _portNumber);
            fflush(stdout);
        }

	if (wait_for_connection) {
            fprintf(stdout, "Waiting for connection ....\n");
            fflush(stdout);
            _fd = accept(_listen_fd, NULL, NULL);
            if (_fd == -1) {
                fprintf(stderr, "accept() error - %s", strerror(errno));
                exit(1);
            }
            setsockopt(_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
            setsockopt(_fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one));
            _connected = true;
        }
}

/*
  see if a new connection is coming in
 */
void SITLUARTDriver::_check_connection(void)
{
	if (_connected) {
            // we only want 1 connection at a time
            return;
	}
	if (_select_check(_listen_fd)) {
            _fd = accept(_listen_fd, NULL, NULL);
            if (_fd != -1) {
                int one = 1;
                _connected = true;
                setsockopt(_fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one));
                setsockopt(_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                fprintf(stdout, "New connection on serial port %u\n", _portNumber);
            }
	}
}

/*
  use select() to see if something is pending
 */
bool SITLUARTDriver::_select_check(int fd)
{
	fd_set fds;
	struct timeval tv;

	FD_ZERO(&fds);
	FD_SET(fd, &fds);

	// zero time means immediate return from select()
	tv.tv_sec = 0;
	tv.tv_usec = 0;

	if (select(fd+1, &fds, NULL, NULL, &tv) == 1) {
		return true;
	}
	return false;
}

void SITLUARTDriver::_set_nonblocking(int fd)
{
	unsigned v = fcntl(fd, F_GETFL, 0);
	fcntl(fd, F_SETFL, v | O_NONBLOCK);
}

#endif