Socket program Python vs C++ (Winsock)..

Question

I have python program which works perfectly for internet chatting. But program built on similar sockets in C++ do not work over internet.
Python program

import thread
import socket


class p2p:
    def __init__(self):
     socket.setdefaulttimeout(50)
     self.port = 3000

     #Destination IP HERE
     self.peerId = '59.95.18.156'

     #declaring sender socket
     self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM  )
     self.socket.bind(('', self.port))
     self.socket.settimeout(50)

     #starting thread for reception
     thread.start_new_thread(self.receiveData, ())

     while 1: 
      data=raw_input('>')
      #print 'sending...'+data
      self.sendData(data)

    def receiveData(self):
     while 1:
      data,address=self.socket.recvfrom(1024)
      print data
    def sendData(self,data):
     self.socket.sendto(data, (self.peerId,self.port))
if __name__=='__main__':
    print 'Started......'  
    p2p()

I want to built similar functionality in c++. I took server and client programs from MSDN. But they are working only on localhost not over internet .. they are as follows...

Sender

#include <stdio.h>
#include "winsock2.h"

void main() {

  WSADATA wsaData;
  SOCKET SendSocket;
  sockaddr_in RecvAddr;
  int Port = 3000;
  char SendBuf[3]={'a','2','\0'};
  int BufLen = 3;

  //---------------------------------------------
  // Initialize Winsock
  WSAStartup(MAKEWORD(2,2), &wsaData);

  //---------------------------------------------
  // Create a socket for sending data
  SendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

  //---------------------------------------------
  // Set up the RecvAddr structure with the IP address of
  // the receiver (in this example case "123.456.789.1")
  // and the specified port number.
  RecvAddr.sin_family = AF_INET;
  RecvAddr.sin_port = htons(Port);
  RecvAddr.sin_addr.s_addr = inet_addr("59.95.18.156");

  //---------------------------------------------
  // Send a datagram to the receiver
  printf("Sending a datagram to the receiver...\n");
  sendto(SendSocket, 
    SendBuf, 
    BufLen, 
    0, 
    (SOCKADDR *) &RecvAddr, 
    sizeof(RecvAddr));

  //---------------------------------------------
  // When the application is finished sending, close the socket.
  printf("Finished sending. Closing socket.\n");
  closesocket(SendSocket);

  //---------------------------------------------
  // Clean up and quit.
  printf("Exiting.\n");
  WSACleanup();
  return;
}

Receiver

#include <stdio.h>
#include "winsock2.h"
#include<iostream>
using namespace std;
void main() {

  WSADATA wsaData;
  SOCKET RecvSocket;
  sockaddr_in RecvAddr;
  int Port = 3000;
  char RecvBuf[3];
  int  BufLen = 3;
  sockaddr_in SenderAddr;
  int SenderAddrSize = sizeof(SenderAddr);

  //-----------------------------------------------
  // Initialize Winsock
  WSAStartup(MAKEWORD(2,2), &wsaData);

  //-----------------------------------------------
  // Create a receiver socket to receive datagrams
  RecvSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

  //-----------------------------------------------
  // Bind the socket to any address and the specified port.
  RecvAddr.sin_family = AF_INET;
  RecvAddr.sin_port = htons(Port);
  RecvAddr.sin_addr.s_addr = htonl(INADDR_ANY);

  bind(RecvSocket, (SOCKADDR *) &RecvAddr, sizeof(RecvAddr));

  //-----------------------------------------------
  // Call the recvfrom function to receive datagrams
  // on the bound socket.
  printf("Receiving datagrams...\n");
  while(true){
  recvfrom(RecvSocket, 
    RecvBuf, 
    BufLen, 
    0, 
    (SOCKADDR *)&SenderAddr, 
    &SenderAddrSize);
    cout<<RecvBuf;
  }
  //-----------------------------------------------
  // Close the socket when finished receiving datagrams
  printf("Finished receiving. Closing socket.\n");
  closesocket(RecvSocket);

  //-----------------------------------------------
  // Clean up and exit.
  printf("Exiting.\n");
  WSACleanup();
  return;
}

Thank you very much for any help ..

Sorry for too much code in the question.

Answer 1

Per the docs, sendto returns a number that's >0 (number of bytes sent) for success, <0 for failure, and in the latter case you use WSAGetLastError for more information. So try saving the sendto result, printing it (as well as the size of the data you're trying to send), and in case of error print the last-error code too. What do you see then?