测试从本地主机接收在 windows 下的 c 中的套接字编程

Question

您好，我是套接字编程的新手。我目前正在为客户端（即我的计算机）编写 c 代码，以向本地主机 127.0.0.1 发送一些内容，并查看本地主机是否收到请求并返回任何内容。我已经可以连接到本地主机，但我不知道我使用什么命令来测试我是否可以与本地主机交谈。

#include<stdio.h>
#include<winsock2.h>

#pragma comment(lib, "ws2_32.lib") //Winsock Library

int main(int argc, char *argv[])
{
    WSADATA wsa;
    SOCKET s;
    struct sockaddr_in server;
    char *message , server_reply[2000];
    int recv_size;


    printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2,2), &wsa) != 0)
    {
        printf("Failed. Error Code : %d", WSAGetLastError());
        return 1;
    }

    printf("Initialised.\n");

    //Create a socket
    if((s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET)
    {
        printf("Could not create socket : %d\n", WSAGetLastError());
        return 1;
    }
    printf("Socket created.\n");
    //server.sin_addr.s_addr = 127.0.0.1; 
    //server.sin_addr.s_addr = inet_addr("74.125.224.72"); //google IP address
    server.sin_addr.s_addr = inet_addr("127.0.0.1"); //local host IP
    server.sin_family = AF_INET;
    //server.sin_port = htons(80);//IIS port
    server.sin_port = htons(60441); //local port
    //server.sin_port = 80;

    //Connect to remote server
    if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        printf("connect error:%d\n", WSAGetLastError());
        closesocket(s);
        WSACleanup();
        system("pause");
        return 1;
    }
    puts("Connected\n");

    closesocket(s);
    WSACleanup();
    system("pause");
    return 0;
}

Answer 1

一旦建立连接，您可以使用send 向远程服务器发送消息，并使用recv 获得回复。您发送的确切内容和期望接收的内容完全取决于您正在使用的服务。

编辑：

例如，假设您正在与 Web 服务器通信，并且您想要检索主页。你可以这样做：

char request[] = "GET / HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n";
size_t bytesSent = send(s, request, strlen(request), 0);
if (bytesSent == -1) {
    printf("Error sending: %d\n", WSAGetLastError());
    return 1;
}

char response[10000];
memset(response, 0, sizeof(response));
size_t bytesRead = recv(s, response, sizeof(response), 0);
if (bytesRead == -1) {
    printf("Error receiving: %d\n", WSAGetLastError());
    return 1;
}

printf("response from web server: %.*s\n", bytesRead, response);