Winsock 编程接口实验

Winsock 是 Windows 操作系统提供的一组用于网络编程的 API。它是 Windows Sockets 的缩写，也称为 Windows 套接字。Winsock 提供了一种通用的网络编程接口，可以使用 TCP/IP、UDP/IP 等协议进行网络通信。

实验步骤：

1. 创建一个 Winsock 应用程序项目，选择 Visual C++ 工程模板，然后选择 Win32 Console Application。

2. 在项目中添加一个源文件，并将其命名为 main.cpp。

3. 在 main.cpp 中包含头文件 #include <winsock2.h>，这是 Winsock API 的主要头文件。

4. 在 main 函数中初始化 Winsock 库，可以调用 WSAStartup 函数。该函数接受两个参数，第一个参数是 Winsock 版本号，第二个参数是指向 WSADATA 结构的指针，用于存储 Winsock 库的信息。

int main()
{
    WSADATA wsaData;
    int iResult;
    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }
    // TODO: Add your application code here
    // Cleanup Winsock
    WSACleanup();
    return 0;
}

5. 在应用程序中使用 Winsock API 进行网络通信。例如，可以创建一个 TCP 客户端，连接到一个服务器，并发送数据。

int main()
{
    WSADATA wsaData;
    int iResult;
    SOCKET ConnectSocket = INVALID_SOCKET;
    struct addrinfo *result = NULL, *ptr = NULL, hints;
    char *sendbuf = "this is a test";
    char recvbuf[DEFAULT_BUFLEN];
    int recvbuflen = DEFAULT_BUFLEN;
    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    // Resolve the server address and port
    iResult = getaddrinfo("www.example.com", "80", &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }
    // Attempt to connect to an address until one succeeds
    for(ptr=result; ptr != NULL ;ptr=ptr->ai_next) {
        // Create a SOCKET for connecting to server
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            printf("Error at socket(): %ld\n", WSAGetLastError());
            freeaddrinfo(result);
            WSACleanup();
            return 1;
        }
        // Connect to server.
        iResult = connect( ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }
    freeaddrinfo(result);
    if (ConnectSocket == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }
    // Send an initial buffer
    iResult = send( ConnectSocket, sendbuf, (int)strlen(sendbuf), 0 );
    if (iResult == SOCKET_ERROR) {
        printf("send failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    printf("Bytes Sent: %ld\n", iResult);
    // shutdown the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    // Receive until the peer closes the connection
    do {
        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if ( iResult > 0 )
            printf("Bytes received: %d\n", iResult);
        else if ( iResult == 0 )
            printf("Connection closed\n");
        else
            printf("recv failed: %d\n", WSAGetLastError());
    } while( iResult > 0 );
    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();
    return 0;
}

以上是 Winsock 编程接口实验的步骤。通过 Winsock 编程接口，可以方便地进行网络编程，实现各种网络应用程序。