设计Linux环境下的UDP socket通信程序，实现服务器端和客户端的通信

以下是一个简单的UDP socket通信程序示例，包括服务器端和客户端的代码：

服务器端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT        12345
#define BUFFER_SIZE 1024

int main(int argc, char *argv[])
{
    int server_fd, ret;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_addr_len = sizeof(client_addr);
    char buffer[BUFFER_SIZE];

    // 创建socket
    server_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (server_fd < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 绑定地址
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(PORT);
    ret = bind(server_fd, (struct sockaddr *)&server_addr, sizeof(server_addr));
    if (ret < 0) {
        perror("bind");
        exit(EXIT_FAILURE);
    }

    // 接收数据
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        ret = recvfrom(server_fd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&client_addr, &client_addr_len);
        if (ret < 0) {
            perror("recvfrom");
            exit(EXIT_FAILURE);
        }
        printf("Receive message from %s:%d: %s\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), buffer);

        // 回复数据
        ret = sendto(server_fd, buffer, strlen(buffer), 0, (struct sockaddr *)&client_addr, client_addr_len);
        if (ret < 0) {
            perror("sendto");
            exit(EXIT_FAILURE);
        }
    }

    close(server_fd);
    return 0;
}

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_IP   "127.0.0.1"
#define PORT        12345
#define BUFFER_SIZE 1024

int main(int argc, char *argv[])
{
    int client_fd, ret;
    struct sockaddr_in server_addr;
    socklen_t server_addr_len = sizeof(server_addr);
    char buffer[BUFFER_SIZE];

    // 创建socket
    client_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (client_fd < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 设置服务器地址
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);
    server_addr.sin_port = htons(PORT);

    // 发送数据
    while (1) {
        printf("Input message: ");
        fgets(buffer, BUFFER_SIZE, stdin);
        ret = sendto(client_fd, buffer, strlen(buffer), 0, (struct sockaddr *)&server_addr, server_addr_len);
        if (ret < 0) {
            perror("sendto");
            exit(EXIT_FAILURE);
        }

        // 接收数据
        memset(buffer, 0, BUFFER_SIZE);
        ret = recvfrom(client_fd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&server_addr, &server_addr_len);
        if (ret < 0) {
            perror("recvfrom");
            exit(EXIT_FAILURE);
        }
        printf("Receive message from %s:%d: %s\n", inet_ntoa(server_addr.sin_addr), ntohs(server_addr.sin_port), buffer);
    }

    close(client_fd);
    return 0;
}

运行以上代码，可以在服务器端和客户端之间进行简单的UDP通信。