如何利用VC源码搭建一个FTP服务器？

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#include <iostream>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <string>
#pragma comment(lib, "ws2_32.lib")
#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "21"
int main() {
    WSADATA wsaData;
    int iResult;
    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        std::cout << "WSAStartup failed: " << iResult << std::endl;
        return 1;
    }
    struct addrinfo *result = NULL, hints;
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;
    // Resolve the server address and port
    iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
    if (iResult != 0) {
        std::cout << "getaddrinfo failed: " << iResult << std::endl;
        WSACleanup();
        return 1;
    }
    SOCKET listenSocket = socket(result>ai_family, result>ai_socktype, result>ai_protocol);
    if (listenSocket == INVALID_SOCKET) {
        std::cout << "Error at socket(): " << WSAGetLastError() << std::endl;
        freeaddrinfo(result);
        WSACleanup();
        return 1;
    }
    // Setup the TCP listening socket
    iResult = bind(listenSocket, result>ai_addr, (int)result>ai_addrlen);
    if (iResult == SOCKET_ERROR) {
        std::cout << "bind failed with error: " << WSAGetLastError() << std::endl;
        freeaddrinfo(result);
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }
    freeaddrinfo(result);
    iResult = listen(listenSocket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        std::cout << "listen failed with error: " << WSAGetLastError() << std::endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }
    SOCKET clientSocket = accept(listenSocket, NULL, NULL);
    if (clientSocket == INVALID_SOCKET) {
        std::cout << "accept failed with error: " << WSAGetLastError() << std::endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }
    char recvbuf[DEFAULT_BUFLEN];
    int recvbuflen = DEFAULT_BUFLEN;
    // Receive data from the client
    iResult = recv(clientSocket, recvbuf, recvbuflen, 0);
    if (iResult > 0) {
        std::cout << "Received: " << recvbuf << std::endl;
    } else if (iResult == 0) {
        std::cout << "Connection closed" << std::endl;
    } else {
        std::cout << "recv failed with error: " << WSAGetLastError() << std::endl;
    }
    // Clean up
    closesocket(clientSocket);
    WSACleanup();
    return 0;
}

这个示例代码创建了一个基本的FTP服务器，它监听端口21并接受一个客户端连接，当客户端连接时，服务器接收来自客户端的数据并将其打印到控制台，这个示例没有实现任何FTP协议的功能，只是简单地接收和显示数据，要实现一个完整的FTP服务器，你需要实现FTP协议的各种命令和响应。