Basic Winsock Program

client.cpp

#include "stdafx.h"
#include <WinSock2.h>
#include <ws2tcpip.h>

#pragma comment(lib, "Ws2_32.lib")

void run_client()
{
    WSADATA wsaData;
    WSAStartup( MAKEWORD(2,2), &wsaData );
    
    ADDRINFO hints, *result;
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    
    getaddrinfo( "127.0.0.1", "80", &hints, &result);
    
    SOCKET client = socket( result->ai_family, result->ai_socktype, result->ai_protocol );
    
    connect( client, result->ai_addr, result->ai_addrlen );
    
    const char* greeting = "hello, I'm client.";
    send( client, greeting, strlen(greeting), 0 );
    
        
    shutdown( ConnectSocket, SD_SEND /*SD_BOTH*/); // finish send
    
    const int buff_len = 512;
    char recv_buff[buff_len];
    recv( client, recv_buff, buff_len, 0);
    
    closesocket(client);
}

server.cpp

#include "stdafx.h"
#include <WinSock2.h>
#include <ws2tcpip.h>

#pragma comment(lib, "Ws2_32.lib")

void run_server() 
{
    WSADATA wsaData;
    WSAStartup( MAKEWORD(2,2), &wsaData );
    
    ADDRINFO hints, *result;
    ZeroMemory(&hints, sizeof(ADDRINFO));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;
    
    getaddrinfo( nullptr, "80", &hints, &result );
    
    SOCKET listen_sock = socket( result->ai_family, result->socktype, result->ai_protocol );
    
    bind( listen_sock, result->ai_addr, (int)result->ai_addrlen );
    
    listen( listen_sock, SOMAXCONN );
    
    SOCKET client = accept( listen_sock, nullptr, nullptr );
    
    const int BUFF_LEN = 512;
    char buff[BUFF_LEN];
    int recv_size = recv( client, buff, BUFF_LEN, 0 );
    send( client, buff, recv_size, 0 );

    closesocket( client ); 
    closesocket( listen_socket );
    WSACleanup();
}