ardupilot/libraries/AP_HAL_SITL/UARTDriver.cpp

/*
   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/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL

#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdarg.h>
#include <AP_Math/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 <sys/select.h>
#include <termios.h>
#include <sys/time.h>

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

extern const AP_HAL::HAL& hal;

using namespace HALSITL;

bool UARTDriver::_console;

/* UARTDriver method implementations */

void UARTDriver::begin(uint32_t baud, uint16_t rxSpace, uint16_t txSpace)
{
    if (_portNumber > ARRAY_SIZE(_sitlState->_uart_path)) {
        AP_HAL::panic("port number out of range; you may need to extend _sitlState->_uart_path");
    }

    const char *path = _sitlState->_uart_path[_portNumber];

    // default to 1MBit
    _uart_baudrate = 1000000U;
    
    if (strcmp(path, "GPS1") == 0) {
        /* gps */
        _connected = true;
        _fd = _sitlState->gps_pipe();
    } else if (strcmp(path, "GPS2") == 0) {
        /* 2nd gps */
        _connected = true;
        _fd = _sitlState->gps2_pipe();
    } else {
        /* parse type:args:flags string for path. 
           For example:
             tcp:5760:wait    // tcp listen on port 5760
             tcp:0:wait       // tcp listen on use base_port + 0
             tcpclient:192.168.2.15:5762
             uart:/dev/ttyUSB0:57600
             sim:ParticleSensor_SDS021:
         */
        char *saveptr = nullptr;
        char *s = strdup(path);
        char *devtype = strtok_r(s, ":", &saveptr);
        char *args1 = strtok_r(nullptr, ":", &saveptr);
        char *args2 = strtok_r(nullptr, ":", &saveptr);
        if (strcmp(devtype, "tcp") == 0) {
            uint16_t port = atoi(args1);
            bool wait = (args2 && strcmp(args2, "wait") == 0);
            _tcp_start_connection(port, wait);
        } else if (strcmp(devtype, "tcpclient") == 0) {
            if (args2 == nullptr) {
                AP_HAL::panic("Invalid tcp client path: %s", path);
            }
            uint16_t port = atoi(args2);
            _tcp_start_client(args1, port);
        } else if (strcmp(devtype, "uart") == 0) {
            uint32_t baudrate = args2? atoi(args2) : baud;
            ::printf("UART connection %s:%u\n", args1, baudrate);
            _uart_path = strdup(args1);
            _uart_baudrate = baudrate;
            _uart_start_connection();
        } else if (strcmp(devtype, "sim") == 0) {
            ::printf("SIM connection %s:%s on port %u\n", args1, args2, _portNumber);
            if (!_connected) {
                _connected = true;
                _fd = _sitlState->sim_fd(args1, args2);
            }
        } else {
            AP_HAL::panic("Invalid device path: %s", path);
        }
        free(s);
    }

    if (hal.console != this) { // don't clear USB buffers (allows early startup messages to escape)
        _readbuffer.clear();
        _writebuffer.clear();
    }

    _set_nonblocking(_fd);
}

void UARTDriver::end()
{
}

uint32_t UARTDriver::available(void)
{
    _check_connection();

    if (!_connected) {
        return 0;
    }

    return _readbuffer.available();
}

uint32_t UARTDriver::txspace(void)
{
    _check_connection();
    if (!_connected) {
        return 0;
    }
    return _writebuffer.space();
}

int16_t UARTDriver::read(void)
{
    if (available() <= 0) {
        return -1;
    }
    uint8_t c;
    _readbuffer.read(&c, 1);
    return c;
}

void UARTDriver::flush(void)
{
}

size_t UARTDriver::write(uint8_t c)
{
    if (txspace() <= 0) {
        return 0;
    }
    _writebuffer.write(&c, 1);
    return 1;
}

size_t UARTDriver::write(const uint8_t *buffer, size_t size)
{
    if (txspace() <= size) {
        size = txspace();
    }
    if (size <= 0) {
        return 0;
    }
    if (_unbuffered_writes) {
        // write buffer straight to the file descriptor
        const ssize_t nwritten = ::write(_fd, buffer, size);
        if (nwritten == -1 && errno != EAGAIN && _uart_path) {
            close(_fd);
            _fd = -1;
            _connected = false;
        }
        // these have no effect
        tcdrain(_fd);
    } else {
        _writebuffer.write(buffer, size);
    }
    return size;
}

    
/*
  start a TCP connection for the serial port. If wait_for_connection
  is true then block until a client connects
 */
void UARTDriver::_tcp_start_connection(uint16_t port, bool wait_for_connection)
{
    int one=1;
    struct sockaddr_in sockaddr;
    int ret;

    if (_connected) {
        return;
    }

    _use_send_recv = true;

    if (_console) {
        // hack for console access
        _connected = true;
        _use_send_recv = false;
        _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
        if (port > 1000) {
            sockaddr.sin_port = htons(port);
        } else {
            sockaddr.sin_port = htons(_sitlState->base_port() + port);
        }
        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);
        }
        ret = fcntl(_listen_fd, F_SETFD, FD_CLOEXEC);
        if (ret == -1) {
            fprintf(stderr, "fcntl failed on setting FD_CLOEXEC - %s\n", strerror(errno));
            exit(1);
        }

        /* we want to be able to re-use ports quickly */
        if (setsockopt(_listen_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) == -1) {
            fprintf(stderr, "setsockopt failed: %s\n", strerror(errno));
            exit(1);
        }

        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, nullptr, nullptr);
        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));
        fcntl(_fd, F_SETFD, FD_CLOEXEC);
        _connected = true;
    }
}


/*
  start a TCP client connection for the serial port. 
 */
void UARTDriver::_tcp_start_client(const char *address, uint16_t port)
{
    int one=1;
    struct sockaddr_in sockaddr;
    int ret;

    if (_connected) {
        return;
    }

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

    memset(&sockaddr,0,sizeof(sockaddr));

#ifdef HAVE_SOCK_SIN_LEN
    sockaddr.sin_len = sizeof(sockaddr);
#endif
    sockaddr.sin_port = htons(port);
    sockaddr.sin_family = AF_INET;
    sockaddr.sin_addr.s_addr = inet_addr(address);

    _fd = socket(AF_INET, SOCK_STREAM, 0);
    if (_fd == -1) {
        fprintf(stderr, "socket failed - %s\n", strerror(errno));
        exit(1);
    }
    ret = fcntl(_fd, F_SETFD, FD_CLOEXEC);
    if (ret == -1) {
        fprintf(stderr, "fcntl failed on setting FD_CLOEXEC - %s\n", strerror(errno));
        exit(1);
    }

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

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

    setsockopt(_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
    setsockopt(_fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one));
    _connected = true;
}


/*
  start a UART connection for the serial port
 */
void UARTDriver::_uart_start_connection(void)
{
    struct termios t {};
    if (!_connected) {
        _fd = ::open(_uart_path, O_RDWR | O_CLOEXEC);
        if (_fd == -1) {
            return;
        }
        // use much smaller buffer sizes on real UARTs
        _writebuffer.set_size(1024);
        _readbuffer.set_size(512);
        ::printf("Opened %s\n", _uart_path);
    }

    if (_fd == -1) {
        AP_HAL::panic("Unable to open UART %s", _uart_path);
    }

    // set non-blocking
    int flags = fcntl(_fd, F_GETFL, 0);
    flags = flags | O_NONBLOCK;
    fcntl(_fd, F_SETFL, flags);

    // disable LF -> CR/LF
    tcgetattr(_fd, &t);
    t.c_iflag &= ~(BRKINT | ICRNL | IMAXBEL | IXON | IXOFF);
    t.c_oflag &= ~(OPOST | ONLCR);
    t.c_lflag &= ~(ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE);
    t.c_cc[VMIN] = 0;
    if (_sitlState->use_rtscts()) {
        t.c_cflag |= CRTSCTS;
    }
    tcsetattr(_fd, TCSANOW, &t);

    // set baudrate
    set_speed(_uart_baudrate);

    _connected = true;
    _use_send_recv = false;
}

/*
  see if a new connection is coming in
 */
void UARTDriver::_check_connection(void)
{
    if (_connected) {
        // we only want 1 connection at a time
        return;
    }
    if (_select_check(_listen_fd)) {
        _fd = accept(_listen_fd, nullptr, nullptr);
        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 UARTDriver::_select_check(int fd)
{
    if (fd == -1) {
        return false;
    }
    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, nullptr, nullptr, &tv) == 1) {
        return true;
    }
    return false;
}

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

bool UARTDriver::set_unbuffered_writes(bool on) {
    if (_fd == -1) {
        return false;
    }
    _unbuffered_writes = on;

    // this has no effect
    unsigned v = fcntl(_fd, F_GETFL, 0);
    v &= ~O_NONBLOCK;
#if defined(__APPLE__) && defined(__MACH__)
    fcntl(_fd, F_SETFL | F_NOCACHE, v | O_SYNC);
#else
    fcntl(_fd, F_SETFL, v | O_DIRECT | O_SYNC);
#endif
    return _unbuffered_writes;
}

void UARTDriver::_check_reconnect(void)
{
    if (!_uart_path) {
        return;
    }
    _uart_start_connection();
}

void UARTDriver::_timer_tick(void)
{
    if (!_connected) {
        _check_reconnect();
        return;
    }
    uint32_t navail;
    ssize_t nwritten;

    const uint8_t *readptr = _writebuffer.readptr(navail);
    if (readptr && navail > 0) {
        if (!_use_send_recv) {
            nwritten = ::write(_fd, readptr, navail);
            if (nwritten == -1 && errno != EAGAIN && _uart_path) {
                close(_fd);
                _fd = -1;
                _connected = false;
            }
        } else {
            nwritten = send(_fd, readptr, navail, MSG_DONTWAIT);
        }
        if (nwritten > 0) {
            _writebuffer.advance(nwritten);
        }
    }

    uint32_t space = _readbuffer.space();
    if (space == 0) {
        return;
    }
    
    char buf[space];
    ssize_t nread = 0;
    if (!_use_send_recv) {
        int fd = _console?0:_fd;
        nread = ::read(fd, buf, space);
        if (nread == -1 && errno != EAGAIN && _uart_path) {
            close(_fd);
            _fd = -1;
            _connected = false;
        }
    } else {
        if (_select_check(_fd)) {
            nread = recv(_fd, buf, space, MSG_DONTWAIT);
            if (nread <= 0) {
                // the socket has reached EOF
                close(_fd);
                _connected = false;
                fprintf(stdout, "Closed connection on serial port %u\n", _portNumber);
                fflush(stdout);
                return;
            }
        } else {
            nread = 0;
        }
    }
    if (nread > 0) {
        _readbuffer.write((uint8_t *)buf, nread);
        _receive_timestamp = AP_HAL::micros64();
    }
}

/*
  return timestamp estimate in microseconds for when the start of
  a nbytes packet arrived on the uart. This should be treated as a
  time constraint, not an exact time. It is guaranteed that the
  packet did not start being received after this time, but it
  could have been in a system buffer before the returned time.
  
  This takes account of the baudrate of the link. For transports
  that have no baudrate (such as USB) the time estimate may be
  less accurate.
  
  A return value of zero means the HAL does not support this API
*/
uint64_t UARTDriver::receive_time_constraint_us(uint16_t nbytes)
{
    uint64_t last_receive_us = _receive_timestamp;
    if (_uart_baudrate > 0) {
        // assume 10 bits per byte. 
        uint32_t transport_time_us = (1000000UL * 10UL / _uart_baudrate) * (nbytes+available());
        last_receive_us -= transport_time_us;
    }
    return last_receive_us;
}

#endif // CONFIG_HAL_BOARD