client.cpp

#include <iostream>
#include <WS2tcpip.h>
using namespace std;
#pragma comment (lib, "WS2_32.LIB")

const char* SERVER_ADDR = "127.0.0.1";
const short SERVER_PORT = 4000;
const int BUFSIZE = 256;

char recv_buf[BUFSIZE];
SOCKET s_socket;
WSABUF mybuf_r;

char send_buf[BUFSIZE];
WSABUF s_wsabuf;

void error_display(const char* msg, int err_no)
{
    WCHAR* lpMsgBuf;
    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER |
        FORMAT_MESSAGE_FROM_SYSTEM,
        NULL, err_no,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR)&lpMsgBuf, 0, NULL);
    std::cout << msg;
    std::wcout << L"¿¡·¯ " << lpMsgBuf << std::endl;
    while (true);
    LocalFree(lpMsgBuf);
}



void CALLBACK send_callback(DWORD err, DWORD num_bytes,
    LPWSAOVERLAPPED lp_over, DWORD s_flag)
{
    delete lp_over;
    return;
}

void CALLBACK recv_callback(DWORD err, DWORD num_bytes,
    LPWSAOVERLAPPED lp_over, DWORD s_flag);

void do_recv(SOCKET s_socket)
{
    mybuf_r.buf = recv_buf;      mybuf_r.len = BUFSIZE;
    DWORD recv_flag = 0;
    WSAOVERLAPPED* r_over = new WSAOVERLAPPED;
    ZeroMemory(r_over, sizeof(WSAOVERLAPPED));
    int ret = WSARecv(s_socket, &mybuf_r, 1, 0, &recv_flag, r_over, recv_callback);
    if (0 != ret) {
        int err_no = WSAGetLastError();
        if (err_no != WSA_IO_PENDING)
            error_display("WSARecv  : ", err_no);
    }
}

void do_send() {
    cout << "Enter Message : ";  cin.getline(send_buf, BUFSIZE);
    s_wsabuf.buf = send_buf;       s_wsabuf.len = static_cast<ULONG>(strlen(send_buf)) + 1;
    WSAOVERLAPPED* s_over = new WSAOVERLAPPED;
    ZeroMemory(s_over, sizeof(WSAOVERLAPPED));
    WSASend(s_socket, &s_wsabuf, 1, 0, 0, s_over, send_callback);
}

void CALLBACK recv_callback(DWORD err, DWORD num_bytes,
    LPWSAOVERLAPPED lp_over, DWORD s_flag)
{
    char* m_start = recv_buf;
    while(true) {
        int message_size = m_start[0];
        int from_client = m_start[1];
        cout << "Client [" << from_client << "] ";
        cout << "Sent[" << message_size << "bytes] : ";
        cout << m_start + 2 << endl;

        num_bytes -= message_size;
        if (0 >= num_bytes) break;
        m_start += message_size;
    }
    delete lp_over;
    do_recv(s_socket);
    do_send();
    return;
}

int main()
{
    wcout.imbue(locale("korean"));
    WSADATA WSAData;
    WSAStartup(MAKEWORD(2, 0), &WSAData);
    s_socket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP,
        0, 0, WSA_FLAG_OVERLAPPED);
    SOCKADDR_IN server_addr;
    ZeroMemory(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, SERVER_ADDR, &server_addr.sin_addr);
    connect(s_socket, reinterpret_cast<sockaddr*>(&server_addr), sizeof(server_addr));
    do_recv(s_socket);
    do_send();
    for (;;) {
        SleepEx(10, true);
    }
    WSACleanup();
}