Sockets not sending data - c++

Question

I'm currently working on an instant messaging system that require a server and a client to communicate between each other.
I tried it in C++ using the default socket API.
The problem is that even if both programs (server & client) compile fine, there isn't any socket sent from the client that reaches the server.
I don't know what did I do wrong here (I went over my code like 5 times and even did it again from scratch, no success).
I used "debugs" messages to locate the problems and they all concern the processing loops that I use.
// code from the server
#include <stdio.h>
#include <tchar.h>
#include <winsock2.h>
#include <stdlib.h>
#include <iostream>
#include <thread>
#include <vector>
#include <Ws2tcpip.h>
#include <string>
int main()
{
std::locale::global(std::locale("fr-FR"));
WSAData wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
std::cout << "Error initializing winsock";
return -1;
}
SOCKET server = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (server == INVALID_SOCKET)
{
std::cout << "Error initializing the socket ";
return -2;
}
const unsigned short port = 9999;
sockaddr_in addr;
addr.sin_addr.s_addr = INADDR_ANY;
addr.sin_port = htons(port);
addr.sin_family = AF_INET;
int res = bind(server, (sockaddr*)&addr, sizeof(addr));
if (res != 0)
{
std::cout << "Error when binding";
return -3;
}
res = listen(server, SOMAXCONN);
if (res != 0)
{
std::cout << "Error on calling listen";
return -4;
}
std::cout << "Server successfully launched" << std::endl;
char buffer[1025];
while (true)
{
sockaddr_in from = { 0 };
int addrlen = sizeof(from);
SOCKET newClient = accept(server, (SOCKADDR*)(&from), &addrlen);
if (newClient != SOCKET_ERROR)
{
std::cout << "Client connected successfully" << std::endl;
int Bytes = recv(newClient, buffer, 1024, 0);
if (Bytes <= 0)
{
break;
}
std::cout << "Message received from client : " << buffer << std::endl;
send(newClient, buffer, 1024, 0); // send it back to client
}
}
return 0;
}
// code from the client
#include <stdio.h>
#include <tchar.h>
#include <winsock2.h>
#include <stdlib.h>
#include <iostream>
#include <thread>
#include <vector>
#include <Ws2tcpip.h>
#include <string>
#define _WINSOCK_DEPRECATED_NO_WARNINGS
void sendMessage(SOCKET s);
void recvMessage(SOCKET s);
int main()
{
std::locale::global(std::locale("fr-FR"));
WSAData wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
{
std::cout << "Error initializing winsock";
return -1;
}
SOCKET server = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (server == INVALID_SOCKET)
{
std::cout << "Error initializing the socket ";
return -2;
}
sockaddr_in addr;
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
addr.sin_port = htons(9999);
int res = bind(server, (sockaddr*)&addr, sizeof(addr));
if (res != 0)
{
std::cout << "Error when binding";
return -3;
}
if (connect(server, (const sockaddr*)&addr, sizeof(addr)) == SOCKET_ERROR)
{
std::cout << "Erreur when connecting : " << WSAGetLastError() << std::endl;
return -4;
}
std::cout << "You are connected to server" << std::endl;
std::thread sending(sendMessage, server);
std::thread receiving(recvMessage, server);
sending.detach();
receiving.detach();
while (true)
{ }
return 0;
}
void sendMessage(SOCKET s)
{
while (true)
{
std::string buff;
std::cout << "Type your message :" << std::endl;
std::getline(std::cin, buff);
std::cout << std::endl;
int Bytes = send(s, buff.c_str(), 1024, 0);
if (Bytes <= 0)
{
break;
}
}
}
void recvMessage(SOCKET s)
{
while (true)
{
char buffer[1025];
int Bytes = recv(s, buffer, 1024, 0);
if (Bytes <= 0)
{
break;
}
std::cout << "The server sent : " << buffer << std::endl;
}
}
The server should display the message that a client has connected when the client is launched and displays the chat command, but the only thing displayed in the server console is the message saying that the server has launched correctly... Yet the client displays the message supposedly "received" by the server.
PS : I'm aware the code doesn't need that many "include" statements, it's just I didn't remember which ones contained which functions so I'd rather include more than not enough for anybody wanting to compile the code.

Answer 1

Several Things:
First, this is wrong:
send(s, buff.c_str(), 1024, 0)
You're basically telling send that the buffer it addresses is a full 1kb, and to send it all. It hasn't a clue how much memory there is actually valid, and knows nothing about terminated strings.
Second, the client setup is wrong. Don't bind to a client socket; connect is sufficient. Notice these:
int res = bind(server, (sockaddr*)&addr, sizeof(addr));
if (res != 0)
{
std::cout << "Error when binding";
return -3;
}
if (connect(server, (const sockaddr*)&addr, sizeof(addr)) == SOCKET_ERROR)
{
std::cout << "Erreur when connecting : " << WSAGetLastError() << std::endl;
return -4;
}
That bind shouldn't be there. The connect will bind to the socket if the connection can be made. Removing the bind section of the client, fixing the buffer management to be correct, and putting closesocket calls where they belong, and your program will be much further down the road to functional. There are still some question logic workflows, but at least the connectivity will be setup better.