allwpilib/src/main/native/cpp/tcpsockets/TCPConnector.cpp

/*
   TCPConnector.h

   TCPConnector class definition. TCPConnector provides methods to actively
   establish TCP/IP connections with a server.

   ------------------------------------------

   Copyright © 2013 [Vic Hargrave - http://vichargrave.com]

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License
*/

#include "tcpsockets/TCPConnector.h"

#include <errno.h>
#include <fcntl.h>
#include <cstdio>
#include <cstring>
#ifdef _WIN32
#include <WinSock2.h>
#include <WS2tcpip.h>
#else
#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <unistd.h>
#endif

#include "tcpsockets/TCPStream.h"

#include "llvm/SmallString.h"
#include "support/Logger.h"
#include "tcpsockets/SocketError.h"

using namespace wpi;

static int ResolveHostName(const char* hostname, struct in_addr* addr) {
  struct addrinfo hints;
  struct addrinfo* res;

  hints.ai_flags = 0;
  hints.ai_family = AF_INET;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;
  hints.ai_addrlen = 0;
  hints.ai_addr = nullptr;
  hints.ai_canonname = nullptr;
  hints.ai_next = nullptr;
  int result = getaddrinfo(hostname, nullptr, &hints, &res);
  if (result == 0) {
    std::memcpy(addr, &((struct sockaddr_in*)res->ai_addr)->sin_addr,
                sizeof(struct in_addr));
    freeaddrinfo(res);
  }
  return result;
}

std::unique_ptr<NetworkStream> TCPConnector::connect(const char* server,
                                                     int port, Logger& logger,
                                                     int timeout) {
#ifdef _WIN32
  struct WSAHelper {
    WSAHelper() {
      WSAData wsaData;
      WORD wVersionRequested = MAKEWORD(2, 2);
      WSAStartup(wVersionRequested, &wsaData);
    }
    ~WSAHelper() { WSACleanup(); }
  };
  static WSAHelper helper;
#endif
  struct sockaddr_in address;

  std::memset(&address, 0, sizeof(address));
  address.sin_family = AF_INET;
  if (ResolveHostName(server, &(address.sin_addr)) != 0) {
#ifdef _WIN32
    llvm::SmallString<128> addr_copy(server);
    addr_copy.push_back('\0');
    int res = InetPton(PF_INET, addr_copy.data(), &(address.sin_addr));
#else
    int res = inet_pton(PF_INET, server, &(address.sin_addr));
#endif
    if (res != 1) {
      WPI_ERROR(logger, "could not resolve " << server << " address");
      return nullptr;
    }
  }
  address.sin_port = htons(port);

  if (timeout == 0) {
    int sd = socket(AF_INET, SOCK_STREAM, 0);
    if (sd < 0) {
      WPI_ERROR(logger, "could not create socket");
      return nullptr;
    }
    if (::connect(sd, (struct sockaddr*)&address, sizeof(address)) != 0) {
      WPI_ERROR(logger, "connect() to " << server << " port " << port << " failed: " << SocketStrerror());
#ifdef _WIN32
      closesocket(sd);
#else
      ::close(sd);
#endif
      return nullptr;
    }
    return std::unique_ptr<NetworkStream>(new TCPStream(sd, &address));
  }

  fd_set sdset;
  struct timeval tv;
  socklen_t len;
  int result = -1, valopt, sd = socket(AF_INET, SOCK_STREAM, 0);
  if (sd < 0) {
    WPI_ERROR(logger, "could not create socket");
    return nullptr;
  }

  // Set socket to non-blocking
#ifdef _WIN32
  u_long mode = 1;
  if (ioctlsocket(sd, FIONBIO, &mode) == SOCKET_ERROR)
    WPI_WARNING(logger,
                "could not set socket to non-blocking: " << SocketStrerror());
#else
  long arg;
  arg = fcntl(sd, F_GETFL, nullptr);
  if (arg < 0) {
    WPI_WARNING(logger,
                "could not set socket to non-blocking: " << SocketStrerror());
  } else {
    arg |= O_NONBLOCK;
    if (fcntl(sd, F_SETFL, arg) < 0)
      WPI_WARNING(logger,
                  "could not set socket to non-blocking: " << SocketStrerror());
  }
#endif

  // Connect with time limit
  if ((result = ::connect(sd, (struct sockaddr*)&address, sizeof(address))) <
      0) {
    int my_errno = SocketErrno();
#ifdef _WIN32
    if (my_errno == WSAEWOULDBLOCK || my_errno == WSAEINPROGRESS) {
#else
    if (my_errno == EWOULDBLOCK || my_errno == EINPROGRESS) {
#endif
      tv.tv_sec = timeout;
      tv.tv_usec = 0;
      FD_ZERO(&sdset);
      FD_SET(sd, &sdset);
      if (select(sd + 1, nullptr, &sdset, nullptr, &tv) > 0) {
        len = sizeof(int);
        getsockopt(sd, SOL_SOCKET, SO_ERROR, (char*)(&valopt), &len);
        if (valopt) {
          WPI_ERROR(logger, "select() to " << server << " port " << port << " error " << valopt << " - " << SocketStrerror(valopt));
        }
        // connection established
        else
          result = 0;
      } else
        WPI_INFO(logger, "connect() to " << server << " port " << port << " timed out");
    } else
      WPI_ERROR(logger, "connect() to " << server << " port " << port << " error " << SocketErrno() << " - " << SocketStrerror());
  }

  // Return socket to blocking mode
#ifdef _WIN32
  mode = 0;
  if (ioctlsocket(sd, FIONBIO, &mode) == SOCKET_ERROR)
    WPI_WARNING(logger,
                "could not set socket to blocking: " << SocketStrerror());
#else
  arg = fcntl(sd, F_GETFL, nullptr);
  if (arg < 0) {
    WPI_WARNING(logger,
                "could not set socket to blocking: " << SocketStrerror());
  } else {
    arg &= (~O_NONBLOCK);
    if (fcntl(sd, F_SETFL, arg) < 0)
      WPI_WARNING(logger,
                  "could not set socket to blocking: " << SocketStrerror());
  }
#endif

  // Create stream object if connected, close if not.
  if (result == -1) {
#ifdef _WIN32
      closesocket(sd);
#else
      ::close(sd);
#endif
    return nullptr;
  }
  return std::unique_ptr<NetworkStream>(new TCPStream(sd, &address));
}