用c++且只用winsock.h实现一个FTP协议的客户端和服务端，完成基本的文件传输功能

好的，我可以为您提供一些思路和代码示例。首先，FTP协议是基于TCP协议的，因此我们需要使用Socket编程来实现FTP客户端和服务端。

以下是FTP客户端的代码示例：

#include <iostream>
#include <fstream>
#include <string>
#include <WinSock2.h>

#pragma comment(lib, "ws2_32.lib")

using namespace std;

int main()
{
    // 初始化Winsock库
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        cout << "WSAStartup failed" << endl;
        return 1;
    }

    // 创建Socket
    SOCKET clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (clientSocket == INVALID_SOCKET)
    {
        cout << "socket failed" << endl;
        WSACleanup();
        return 1;
    }

    // 连接服务器
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(21);
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    if (connect(clientSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR)
    {
        cout << "connect failed" << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }

    // 接收服务器欢迎信息
    char buf[1024];
    int recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    if (recvLen == SOCKET_ERROR)
    {
        cout << "recv failed" << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    buf[recvLen] = '\0';
    cout << buf;

    // 发送用户名和密码
    send(clientSocket, "USER username\r\n", 15, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;
    send(clientSocket, "PASS password\r\n", 15, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;

    // 上传文件
    ifstream ifs("test.txt", ios::binary);
    if (!ifs.is_open())
    {
        cout << "open file failed" << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    send(clientSocket, "TYPE I\r\n", 8, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;
    send(clientSocket, "PASV\r\n", 6, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;
    int port = 0;
    char* p = strstr(buf, "(");
    sscanf(p, "(%*d,%*d,%*d,%*d,%d,%*d)", &port);
    sockaddr_in dataAddr;
    dataAddr.sin_family = AF_INET;
    dataAddr.sin_port = htons(port);
    dataAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    SOCKET dataSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (dataSocket == INVALID_SOCKET)
    {
        cout << "socket failed" << endl;
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    if (connect(dataSocket, (sockaddr*)&dataAddr, sizeof(dataAddr)) == SOCKET_ERROR)
    {
        cout << "connect failed" << endl;
        closesocket(dataSocket);
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    send(clientSocket, "STOR test.txt\r\n", 15, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;
    while (ifs.good())
    {
        ifs.read(buf, sizeof(buf));
        int sendLen = send(dataSocket, buf, ifs.gcount(), 0);
        if (sendLen == SOCKET_ERROR)
        {
            cout << "send failed" << endl;
            closesocket(dataSocket);
            closesocket(clientSocket);
            WSACleanup();
            return 1;
        }
    }
    ifs.close();
    closesocket(dataSocket);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;

    // 断开连接
    send(clientSocket, "QUIT\r\n", 6, 0);
    recvLen = recv(clientSocket, buf, sizeof(buf), 0);
    buf[recvLen] = '\0';
    cout << buf;
    closesocket(clientSocket);

    // 清理Winsock库
    WSACleanup();

    return 0;
}

以上代码实现了一个简单的FTP客户端，其中包括连接服务器、发送用户名和密码、上传文件等功能。

下面是FTP服务端的代码示例：

#include <iostream>
#include <fstream>
#include <string>
#include <WinSock2.h>

#pragma comment(lib, "ws2_32.lib")

using namespace std;

int main()
{
    // 初始化Winsock库
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        cout << "WSAStartup failed" << endl;
        return 1;
    }

    // 创建Socket
    SOCKET listenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (listenSocket == INVALID_SOCKET)
    {
        cout << "socket failed" << endl;
        WSACleanup();
        return 1;
    }

    // 绑定IP地址和端口号
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(21);
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    if (bind(listenSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR)
    {
        cout << "bind failed" << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    // 监听客户端连接请求
    if (listen(listenSocket, SOMAXCONN) == SOCKET_ERROR)
    {
        cout << "listen failed" << endl;
        closesocket(listenSocket);
        WSACleanup();
        return 1;
    }

    while (true)
    {
        // 接受客户端连接
        SOCKET clientSocket = accept(listenSocket, NULL, NULL);
        if (clientSocket == INVALID_SOCKET)
        {
            cout << "accept failed" << endl;
            closesocket(listenSocket);
            WSACleanup();
            return 1;
        }

        // 发送欢迎信息
        const char* welcomeMsg = "220 Welcome to FTP server\r\n";
        send(clientSocket, welcomeMsg, strlen(welcomeMsg), 0);

        // 接收用户名和密码
        char buf[1024];
        int recvLen = recv(clientSocket, buf, sizeof(buf), 0);
        if (recvLen == SOCKET_ERROR)
        {
            cout << "recv failed" << endl;
            closesocket(clientSocket);
            continue;
        }
        buf[recvLen] = '\0';
        cout << buf;
        send(clientSocket, "331 Password required\r\n", 24, 0);
        recvLen = recv(clientSocket, buf, sizeof(buf), 0);
        if (recvLen == SOCKET_ERROR)
        {
            cout << "recv failed" << endl;
            closesocket(clientSocket);
            continue;
        }
        buf[recvLen] = '\0';
        cout << buf;
        send(clientSocket, "230 Logged in\r\n", 15, 0);

        // 接收上传文件指令
        recvLen = recv(clientSocket, buf, sizeof(buf), 0);
        if (recvLen == SOCKET_ERROR)
        {
            cout << "recv failed" << endl;
            closesocket(clientSocket);
            continue;
        }
        buf[recvLen] = '\0';
        cout << buf;
        send(clientSocket, "200 Type set to I\r\n", 19, 0);
        send(clientSocket, "227 Entering Passive Mode (127,0,0,1,0,21)\r\n", 44, 0);
        sockaddr_in dataAddr;
        int dataAddrLen = sizeof(dataAddr);
        SOCKET dataSocket = accept(listenSocket, (sockaddr*)&dataAddr, &dataAddrLen);
        if (dataSocket == INVALID_SOCKET)
        {
            cout << "accept failed" << endl;
            closesocket(clientSocket);
            continue;
        }
        recvLen = recv(clientSocket, buf, sizeof(buf), 0);
        if (recvLen == SOCKET_ERROR)
        {
            cout << "recv failed" << endl;
            closesocket(clientSocket);
            closesocket(dataSocket);
            continue;
        }
        buf[recvLen] = '\0';
        cout << buf;
        ofstream ofs("test.txt", ios::binary);
        if (!ofs.is_open())
        {
            cout << "open file failed" << endl;
            closesocket(clientSocket);
            closesocket(dataSocket);
            continue;
        }
        while (true)
        {
            recvLen = recv(dataSocket, buf, sizeof(buf), 0);
            if (recvLen == SOCKET_ERROR)
            {
                cout << "recv failed" << endl;
                closesocket(clientSocket);
                closesocket(dataSocket);
                break;
            }
            else if (recvLen == 0)
            {
                break;
            }
            int writeLen = ofs.write(buf, recvLen).tellp();
            if (writeLen == -1)
            {
                cout << "write file failed" << endl;
                closesocket(clientSocket);
                closesocket(dataSocket);
                break;
            }
        }
        ofs.close();
        closesocket(dataSocket);
        send(clientSocket, "226 Transfer complete\r\n", 23, 0);

        // 断开连接
        recvLen = recv(clientSocket, buf, sizeof(buf), 0);
        if (recvLen == SOCKET_ERROR)
        {
            cout << "recv failed" << endl;
            closesocket(clientSocket);
            continue;
        }
        buf[recvLen] = '\0';
        cout << buf;
        send(clientSocket, "221 Goodbye\r\n", 14, 0);
        closesocket(clientSocket);
    }

    // 关闭Socket
    closesocket(listenSocket);

    // 清理Winsock库
    WSACleanup();

    return 0;
}

以上代码实现了一个简单的FTP服务端，其中包括接受客户端连接、发送欢迎信息、接收用户名和密码、上传文件等功能。

请注意，以上代码仅为示例，实际使用时需要进行一定的安全性和稳定性优化。