// -*-c++-*-//===========================================================//=     University of Illinois at Urbana-Champaign          =//=     Department of Computer Science                      =//=     Dr. Dan Roth - Cognitive Computation Group          =//=                                                         =//=  Project: SNoW                                          =//=                                                         =//=   Module: SendReceive.h                                 =//=  Version: 3.2.0                                         =//=  Authors: Nick Rizzolo                                  =//=     Date: 8/24/01                                       = //=                                                         =//= Comments: Sends the size of the data in bytes before    =//=           sending the actual data.  Expects the same in =//=           in return.  The size variable is a 4 byte,    =//=           big-endian (network standard) integer.        =//=           As of 7/5/02, the handle_recv_error()         =//=           function is lacking (although I've never run  =//=           into problems).  If anyone would like to make =//=           it better, feel free.                         =//===========================================================#ifndef SEND_AND_RECEIVE_#define SEND_AND_RECEIVE_//#define VERBOSE#include <stdio.h>#include <sys/types.h>#include <sys/socket.h>#include <sys/uio.h>#include <ctype.h>#include <errno.h>#include <iostream>using std::cout;int send_bytes( int socket, const char* message, int length, int flags );int receive_bytes( int socket, char* &message, int flags );int handle_recv_error();unsigned char __little_endian(2); /*****  * resolve_endianness() reverses the byte order of its parameter n if the  *   machine this code is compiled on is little endian. **/void resolve_endianness(int& n){  int i;  if (__little_endian == 2)  {    i = 1;    __little_endian = *((char*) &i);  }  if (__little_endian == 1)  {    n = ((n >>  8) & 0x00FF00FF) | ((n <<  8) & 0xFF00FF00);    n = ((n >> 16) & 0x0000FFFF) | ((n << 16) & 0xFFFF0000);  }} /*****  * send_bytes() is an interface to the send() function that first sends the  *   length of the message to the socket as an integer, so that the other  *   party knows how much data to expect.  *  * parameters: same as send()  * returns:    same as send() **/int send_bytes( int socket, const char* message, int length, int flags ){  resolve_endianness(length);  send(socket, &length, 4, flags);  resolve_endianness(length);#ifdef VERBOSE  cout << "\nSending " << length << " bytes.\n";#endif  return send(socket, message, length, flags);} /*****  * receive_bytes() is an interface to the recv() function that first receives  *   the length of the message that it expects to receive next.  It then  *   executes recv() in a loop while the entire expected message has not yet  *   been received.  *  * parameters:  *   - int socket:    The connected socket to receive from.  *   - char* message: The buffer into which data should be received.  *   - int flags:     See the recv() man page.  *  * returns:    same as recv() **/int receive_bytes( int socket, char* &message, int flags ){  int temp;  struct  {    int received;    union    {      int length;      char buffer;    } expected;  } incoming;  int i;  if (__little_endian == 2)  {    i = 1;    __little_endian = *((char*) &i);  }  incoming.received = 0;  do  {    temp = recv(socket, &incoming.expected.buffer + incoming.received,                sizeof(int) - incoming.received, flags);    if (temp == 0) return 0;    if (temp == -1 && handle_recv_error() == -1) return -1;    incoming.received += temp;  } while (incoming.received < sizeof(int));  if (incoming.expected.length == 0) return 0;  resolve_endianness(incoming.expected.length);  incoming.received = temp = 0;  /*  while (temp < 1)  {     temp = recv(socket, message, 1, flags);    if (temp == -1 && handle_recv_error() == -1) return -1;  }  if (message[0] == '\0') --incoming.expected.length;  else ++incoming.received;  */#ifdef VERBOSE  cout << "\nExpecting " << incoming.expected.length       << " bytes in message.\n";#endif  message = new char[incoming.expected.length + 1];  message[incoming.expected.length] = '\0';  while (incoming.received < incoming.expected.length)  {    temp = recv(socket, message + incoming.received,                incoming.expected.length - incoming.received, flags);    if (temp == -1 && handle_recv_error() == -1) return -1;    incoming.received += temp;    if (temp == 0)    {      message[incoming.received] = '\0';      break;    }  }#ifdef VERBOSE  cout << "Received " << incoming.received << " bytes.\n\n";#endif  return incoming.received;}int handle_recv_error(){  char* first_part = "recv error #";  char* message = new char[20];  sprintf(message, "%s%d", first_part, errno);  switch (errno)  {    case EBADF:    case EINTR:    case EIO:    case ENOMEM:    // case ENOSR:    case ENOTSOCK:    case ESTALE:    case EWOULDBLOCK: break;    case 2: cout << "Bad address\n"; return 0;    default: cout << "unknown error\n";  }  perror(message);  return -1;}#endif