Quadrotor

/*

 *  Udp.cpp: Library to send/receive UDP packets with the Arduino ethernet shield.

 *  This version only offers minimal wrapping of socket.c/socket.h

 *  Drop Udp.h/.cpp into the Ethernet library directory at hardware/libraries/Ethernet/ 

 *

 * MIT License:

 * Copyright (c) 2008 Bjoern Hartmann

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 *

 * bjoern@cs.stanford.edu 12/30/2008

 */

#include "w5100.h"

#include "socket.h"

#include "Ethernet.h"

#include "Udp.h"

#include "Dns.h"

/* Constructor */

EthernetUDP::EthernetUDP() : _sock(MAX_SOCK_NUM) {}

/* Start EthernetUDP socket, listening at local port PORT */

uint8_t EthernetUDP::begin(uint16_t port) {

  if (_sock != MAX_SOCK_NUM)

    return 0;

  for (int i = 0; i < MAX_SOCK_NUM; i++) {

    uint8_t s = W5100.readSnSR(i);

    if (s == SnSR::CLOSED || s == SnSR::FIN_WAIT) {

      _sock = i;

      break;

    }

  }

  if (_sock == MAX_SOCK_NUM)

    return 0;

  _port = port;

  socket(_sock, SnMR::UDP, _port, 0);

  return 1;

}

/* Is data available in rx buffer? Returns 0 if no, number of available bytes if yes. 

 * returned value includes 8 byte UDP header!*/

int EthernetUDP::available() {

  return W5100.getRXReceivedSize(_sock);

}

/* Release any resources being used by this EthernetUDP instance */

void EthernetUDP::stop()

{

  if (_sock == MAX_SOCK_NUM)

    return;

  close(_sock);

  EthernetClass::_server_port[_sock] = 0;

  _sock = MAX_SOCK_NUM;

}

int EthernetUDP::beginPacket(const char *host, uint16_t port)

{

  // Look up the host first

  int ret = 0;

  DNSClient dns;

  IPAddress remote_addr;

  dns.begin(Ethernet.dnsServerIP());

  ret = dns.getHostByName(host, remote_addr);

  if (ret == 1) {

    return beginPacket(remote_addr, port);

  } else {

    return ret;

  }

}

int EthernetUDP::beginPacket(IPAddress ip, uint16_t port)

{

  _offset = 0;

  return startUDP(_sock, rawIPAddress(ip), port);

}

int EthernetUDP::endPacket()

{

  return sendUDP(_sock);

}

size_t EthernetUDP::write(uint8_t byte)

{

  return write(&byte, 1);

}

size_t EthernetUDP::write(const uint8_t *buffer, size_t size)

{

  uint16_t bytes_written = bufferData(_sock, _offset, buffer, size);

  _offset += bytes_written;

  return bytes_written;

}

int EthernetUDP::parsePacket()

{

  if (available() > 0)

  {

    //HACK - hand-parse the UDP packet using TCP recv method

    uint8_t tmpBuf[8];

    int ret =0;        

    //read 8 header bytes and get IP and port from it

    ret = recv(_sock,tmpBuf,8);

    if (ret > 0)

    {

      _remoteIP = tmpBuf;

      _remotePort = tmpBuf[4];

      _remotePort = (_remotePort << 8) + tmpBuf[5];

      // When we get here, any remaining bytes are the data

      ret = available();

    }

    return ret;

  }

  // There aren't any packets available

  return 0;

}

int EthernetUDP::read()

{

  uint8_t byte;

  if (recv(_sock, &byte, 1) > 0)

  {

    // We read things without any problems

    return byte;

  }

  // If we get here, there's no data available

  return -1;

}

int EthernetUDP::read(unsigned char* buffer, size_t len)

{

  /* In the readPacket that copes with truncating packets, the buffer was

     filled with this code.  Not sure why it loops round reading out a byte

     at a time.

  int i;

  for(i=0;i<(int)bufLen;i++) {

    recv(_sock,tmpBuf,1);

    buf[i]=tmpBuf[0];

  }

  */

  return recv(_sock, buffer, len);

}

int EthernetUDP::peek()

{

  uint8_t b;

  // Unlike recv, peek doesn't check to see if there's any data available, so we must

  if (!available())

    return -1;

  ::peek(_sock, &b);

  return b;

}

void EthernetUDP::flush()

{

  while (available())

  {

    read();

  }

}