socket应用的例子

当使用 C 语言实现 Socket 编程时，可以通过系统提供的网络库来实现网络通信。以下是一个简单的示例，演示了如何创建一个简单的服务器和客户端，实现客户端向服务器发送消息并接收回复的功能。

服务器端（server.c）#

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>

#define PORT 8080
#define MAX_BUFFER_SIZE 1024

int main() {
    int server_socket, client_socket;
    struct sockaddr_in server_addr, client_addr;
    char buffer[MAX_BUFFER_SIZE] = {0};

    // 创建 Socket
    if ((server_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("Socket creation failed");
        exit(EXIT_FAILURE);
    }

    // 设置服务器地址和端口
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(PORT);

    // 绑定 Socket
    if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("Socket bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听连接
    if (listen(server_socket, 5) == -1) {
        perror("Listen failed");
        exit(EXIT_FAILURE);
    }

    printf("Server listening on port %d\n", PORT);

    while (1) {
        socklen_t client_addr_len = sizeof(client_addr);

        // 等待客户端连接
        client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_len);
        if (client_socket == -1) {
            perror("Accept failed");
            continue;
        }

        printf("Client connected: %s\n", inet_ntoa(client_addr.sin_addr));

        // 接收客户端消息
        int bytes_received = recv(client_socket, buffer, MAX_BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            perror("Receive failed");
            close(client_socket);
            continue;
        }

        // 处理客户端消息
        printf("Received from client: %s\n", buffer);

        // 发送回复给客户端
        const char *reply_message = "Hello, client! I received your message.";
        send(client_socket, reply_message, strlen(reply_message), 0);

        close(client_socket);
    }

    close(server_socket);
    return 0;
}

客户端（client.c）#

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>

#define SERVER_IP "127.0.0.1"
#define PORT 8080
#define MAX_BUFFER_SIZE 1024

int main() {
    int client_socket;
    struct sockaddr_in server_addr;
    char buffer[MAX_BUFFER_SIZE] = {0};

    // 创建 Socket
    if ((client_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("Socket creation failed");
        exit(EXIT_FAILURE);
    }

    // 设置服务器地址和端口
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    if (inet_pton(AF_INET, SERVER_IP, &server_addr.sin_addr) <= 0) {
        perror("Invalid address");
        exit(EXIT_FAILURE);
    }

    // 连接服务器
    if (connect(client_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("Connection failed");
        exit(EXIT_FAILURE);
    }

    // 发送消息给服务器
    const char *message = "Hello, server! I am a client.";
    send(client_socket, message, strlen(message), 0);

    // 接收服务器回复
    int bytes_received = recv(client_socket, buffer, MAX_BUFFER_SIZE, 0);
    if (bytes_received <= 0) {
        perror("Receive failed");
        close(client_socket);
        exit(EXIT_FAILURE);
    }

    printf("Received from server: %s\n", buffer);

    close(client_socket);
    return 0;
}