Establishing a TCP connection

tcp_connect.cpp

int connect(const std::string &host, const int port, const int timeout){
 struct sockaddr_in sa = {0};
 int socket;

 // Create and populate the connect address structure
 sa.sin_family = AF_INET;

 // The htons() function converts the unsigned short integer hostshort 
 // from host byte order to network byte order
 // On the i80x86 the host byte order is least significant byte first,
 // whereas the network byte order, as used on the Internet, is the
 // most significant byte first
 sa.sin_port = htons(port);
 inet_pton(AF_INET, host.c_str(), &(sa.sin_addr));

 // Not an IP address - attempt to resolve as a hostname instead
 if (sa.sin_addr.s_addr == (in_addr_t)(-1)){
  struct hostent *hostentry;
  hostentry = gethostbyname(host.c_str());
  if(!hostentry){
   std::ostringstream ss;
   ss << "connect: gethostybname error: " << hstrerror(h_errno);
   cout << ss;
   return -1;
  }
  if (hostentry->h_addrtype != AF_INET){
   cout << "connect: h_addrtype == " << hostentry->h_addrtype 
   << ", only support " << AF_INET << " (AF_INET);
  }
  if (!hostentry->h_addr_list[0]){
   cout << "connect: no addresses found";
   return -1;
  }
  sa.sin_addr = *(struct in_addr *)hostentry->h_addr_list[0];
 }

 socket = socket(AF_INET, SOCK_STREAM, 0);

 if(socket < 0){
  cout << "connect: failed to create socket " << socket;
  return -1;
 }

 setNonBlocking(socket);
 setNoDelay(socket);
 setBuffer(socket, 2048);

 // Doing a non-blocking connect, expecting to get EINPROGRESS
 int result;
 if((result = connect(socket, (struct sockaddr *)&sa, sizeof(sa))) != 0 && errno != EINPROGRESS){
  cout << "connect: failed to connect " << result;
  if(socket>=0) ::close(socket);
  return -1;
 }

 // Poll once to confirm connection is established
 struct pollfd fds[1];
 if(timeout <= 0 || timeout > 30000) timeout = 30000;

 result = 0;
 fds[0].fd = socket;
 fds[0].revents = 0;
 fds[0].events = POLLIN | POLLOUT;

 if((result = poll((struct pollfd *)&fds, 1, timeout)) == 0){
  ::close(socket);
  cout << "connect: Connection timeout " << timeout;
  return -1;
 }
 else if(result < 0){
  ::close(socket);
  cout << "connect: poll failed, error " << errno;
  return -1;
 }
 else if(fds[0].revents & POLLOUT) != 0){
  int error = 0;
  int len = sizeof(error);
  if(getsockopt(socket, SOL_SOCKET, SO_ERROR, &error, (socklen_t *)&len) < 0){
   ::close(socket);
   cout << "connect: Poll error " << error;
   return -1;
  }
  else{
   cout << "connect: success, revents " << fds[0].revents;
   result = 0;
  }
 }

 if(result == -1){
  ::close(socket);
  return -1;
 }

 return socket;
}