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met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the
  above copyright notice, this list of conditions
  and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

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  nor the names of its contributors may be used to
  endorse or promote products derived from this
  software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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****************************************************************************/

/****************************************************************************
written by
   Yunhong Gu, last updated 01/27/2011
*****************************************************************************/

#ifndef WIN32
   #include <netdb.h>
   #include <arpa/inet.h>
   #include <unistd.h>
   #include <fcntl.h>
   #include <cstring>
   #include <cstdio>
   #include <cerrno>
#else
   #include <winsock2.h>
   #include <ws2tcpip.h>
   #ifdef LEGACY_WIN32
      #include <wspiapi.h>
   #endif
#endif
#include "channel.h"
#include "packet.h"

#ifdef WIN32
   #define socklen_t int
#endif

#ifndef WIN32
   #define NET_ERROR errno
#else
   #define NET_ERROR WSAGetLastError()
#endif


CChannel::CChannel():
m_iIPversion(AF_INET),
m_iSockAddrSize(sizeof(sockaddr_in)),
m_iSocket(),
m_iSndBufSize(65536),
m_iRcvBufSize(65536)
{
}

CChannel::CChannel(const int& version):
m_iIPversion(version),
m_iSocket(),
m_iSndBufSize(65536),
m_iRcvBufSize(65536)
{
   m_iSockAddrSize = (AF_INET == m_iIPversion) ? sizeof(sockaddr_in) : sizeof(sockaddr_in6);
}

CChannel::~CChannel()
{
}

void CChannel::open(const sockaddr* addr)
{
   // construct an socket
   m_iSocket = socket(m_iIPversion, SOCK_DGRAM, 0);

   #ifdef WIN32
      if (INVALID_SOCKET == m_iSocket)
   #else
      if (m_iSocket < 0)
   #endif
      throw CUDTException(1, 0, NET_ERROR);

   if (NULL != addr)
   {
      socklen_t namelen = m_iSockAddrSize;

      if (0 != bind(m_iSocket, addr, namelen))
         throw CUDTException(1, 3, NET_ERROR);
   }
   else
   {
      //sendto or WSASendTo will also automatically bind the socket
      addrinfo hints;
      addrinfo* res;

      memset(&hints, 0, sizeof(struct addrinfo));

      hints.ai_flags = AI_PASSIVE;
      hints.ai_family = m_iIPversion;
      hints.ai_socktype = SOCK_DGRAM;

      if (0 != getaddrinfo(NULL, "0", &hints, &res))
         throw CUDTException(1, 3, NET_ERROR);

      if (0 != bind(m_iSocket, res->ai_addr, res->ai_addrlen))
         throw CUDTException(1, 3, NET_ERROR);

      freeaddrinfo(res);
   }

   setUDPSockOpt();
}

void CChannel::open(UDPSOCKET udpsock)
{
   m_iSocket = udpsock;
   setUDPSockOpt();
}

void CChannel::setUDPSockOpt()
{
   #if defined(BSD) || defined(OSX)
      // BSD system will fail setsockopt if the requested buffer size exceeds system maximum value
      int maxsize = 64000;
      if (0 != setsockopt(m_iSocket, SOL_SOCKET, SO_RCVBUF, (char*)&m_iRcvBufSize, sizeof(int)))
         setsockopt(m_iSocket, SOL_SOCKET, SO_RCVBUF, (char*)&maxsize, sizeof(int));
      if (0 != setsockopt(m_iSocket, SOL_SOCKET, SO_SNDBUF, (char*)&m_iSndBufSize, sizeof(int)))
         setsockopt(m_iSocket, SOL_SOCKET, SO_SNDBUF, (char*)&maxsize, sizeof(int));
   #else
      // for other systems, if requested is greated than maximum, the maximum value will be automactally used
      if ((0 != setsockopt(m_iSocket, SOL_SOCKET, SO_RCVBUF, (char*)&m_iRcvBufSize, sizeof(int))) ||
          (0 != setsockopt(m_iSocket, SOL_SOCKET, SO_SNDBUF, (char*)&m_iSndBufSize, sizeof(int))))
         throw CUDTException(1, 3, NET_ERROR);
   #endif

   timeval tv;
   tv.tv_sec = 0;
   #if defined (BSD) || defined (OSX)
      // Known BSD bug as the day I wrote this code.
      // A small time out value will cause the socket to block forever.
      tv.tv_usec = 10000;
   #else
      tv.tv_usec = 100;
   #endif

   #ifdef UNIX
      // Set non-blocking I/O
      // UNIX does not support SO_RCVTIMEO
      int opts = fcntl(m_iSocket, F_GETFL);
      if (-1 == fcntl(m_iSocket, F_SETFL, opts | O_NONBLOCK))
         throw CUDTException(1, 3, NET_ERROR);
   #elif WIN32
      DWORD ot = 1; //milliseconds
      if (0 != setsockopt(m_iSocket, SOL_SOCKET, SO_RCVTIMEO, (char *)&ot, sizeof(DWORD)))
         throw CUDTException(1, 3, NET_ERROR);
   #else
      // Set receiving time-out value
      if (0 != setsockopt(m_iSocket, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof(timeval)))
         throw CUDTException(1, 3, NET_ERROR);
   #endif
}

void CChannel::close() const
{
   #ifndef WIN32
      ::close(m_iSocket);
   #else
      closesocket(m_iSocket);
   #endif
}

int CChannel::getSndBufSize()
{
   socklen_t size = sizeof(socklen_t);

   getsockopt(m_iSocket, SOL_SOCKET, SO_SNDBUF, (char *)&m_iSndBufSize, &size);

   return m_iSndBufSize;
}

int CChannel::getRcvBufSize()
{
   socklen_t size = sizeof(socklen_t);

   getsockopt(m_iSocket, SOL_SOCKET, SO_RCVBUF, (char *)&m_iRcvBufSize, &size);

   return m_iRcvBufSize;
}

void CChannel::setSndBufSize(const int& size)
{
   m_iSndBufSize = size;
}

void CChannel::setRcvBufSize(const int& size)
{
   m_iRcvBufSize = size;
}

void CChannel::getSockAddr(sockaddr* addr) const
{
   socklen_t namelen = m_iSockAddrSize;

   getsockname(m_iSocket, addr, &namelen);
}

void CChannel::getPeerAddr(sockaddr* addr) const
{
   socklen_t namelen = m_iSockAddrSize;

   getpeername(m_iSocket, addr, &namelen);
}

int CChannel::sendto(const sockaddr* addr, CPacket& packet) const
{
   // convert control information into network order
   if (packet.getFlag())
      for (int i = 0, n = packet.getLength() / 4; i < n; ++ i)
         *((uint32_t *)packet.m_pcData + i) = htonl(*((uint32_t *)packet.m_pcData + i));

   // convert packet header into network order
   //for (int j = 0; j < 4; ++ j)
   //   packet.m_nHeader[j] = htonl(packet.m_nHeader[j]);
   uint32_t* p = packet.m_nHeader;
   for (int j = 0; j < 4; ++ j)
   {
      *p = htonl(*p);
      ++ p;
   }

   #ifndef WIN32
      msghdr mh;
      mh.msg_name = (sockaddr*)addr;
      mh.msg_namelen = m_iSockAddrSize;
      mh.msg_iov = (iovec*)packet.m_PacketVector;
      mh.msg_iovlen = 2;
      mh.msg_control = NULL;
      mh.msg_controllen = 0;
      mh.msg_flags = 0;

      int res = sendmsg(m_iSocket, &mh, 0);
   #else
      DWORD size = CPacket::m_iPktHdrSize + packet.getLength();
      int addrsize = m_iSockAddrSize;
      int res = WSASendTo(m_iSocket, (LPWSABUF)packet.m_PacketVector, 2, &size, 0, addr, addrsize, NULL, NULL);
      res = (0 == res) ? size : -1;
   #endif

   // convert back into local host order
   //for (int k = 0; k < 4; ++ k)
   //   packet.m_nHeader[k] = ntohl(packet.m_nHeader[k]);
   p = packet.m_nHeader;
   for (int k = 0; k < 4; ++ k)
   {
      *p = ntohl(*p);
       ++ p;
   }

   if (packet.getFlag())
   {
      for (int l = 0, n = packet.getLength() / 4; l < n; ++ l)
         *((uint32_t *)packet.m_pcData + l) = ntohl(*((uint32_t *)packet.m_pcData + l));
   }

   return res;
}

int CChannel::recvfrom(sockaddr* addr, CPacket& packet) const
{
   #ifndef WIN32
      msghdr mh;   
      mh.msg_name = addr;
      mh.msg_namelen = m_iSockAddrSize;
      mh.msg_iov = packet.m_PacketVector;
      mh.msg_iovlen = 2;
      mh.msg_control = NULL;
      mh.msg_controllen = 0;
      mh.msg_flags = 0;

      #ifdef UNIX
         fd_set set;
         timeval tv;
         FD_ZERO(&set);
         FD_SET(m_iSocket, &set);
         tv.tv_sec = 0;
         tv.tv_usec = 10000;
         select(m_iSocket+1, &set, NULL, &set, &tv);
      #endif

      int res = recvmsg(m_iSocket, &mh, 0);
   #else
      DWORD size = CPacket::m_iPktHdrSize + packet.getLength();
      DWORD flag = 0;
      int addrsize = m_iSockAddrSize;

      int res = WSARecvFrom(m_iSocket, (LPWSABUF)packet.m_PacketVector, 2, &size, &flag, addr, &addrsize, NULL, NULL);
      res = (0 == res) ? size : -1;
   #endif

   if (res <= 0)
   {
      packet.setLength(-1);
      return -1;
   }

   packet.setLength(res - CPacket::m_iPktHdrSize);

   // convert back into local host order
   //for (int i = 0; i < 4; ++ i)
   //   packet.m_nHeader[i] = ntohl(packet.m_nHeader[i]);
   uint32_t* p = packet.m_nHeader;
   for (int i = 0; i < 4; ++ i)
   {
      *p = ntohl(*p);
      ++ p;
   }

   if (packet.getFlag())
   {
      for (int j = 0, n = packet.getLength() / 4; j < n; ++ j)
         *((uint32_t *)packet.m_pcData + j) = ntohl(*((uint32_t *)packet.m_pcData + j));
   }

   return packet.getLength();
}
