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

#define PORT 12345    // 服務(wù)器監(jiān)聽的端口號(hào)
#define BUFFER_SIZE 1024  // 緩沖區(qū)大小
 
int main() {
    int sockfd;
    char buffer[BUFFER_SIZE];
    struct sockaddr_in server_addr, client_addr;
    socklen_t addr_len;
    ssize_t n;
 
    // 創(chuàng)建UDP套接字
    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        perror("創(chuàng)建套接字失敗");
        exit(EXIT_FAILURE);
    }
 
    // 配置服務(wù)器地址
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET; // IPv4
    server_addr.sin_addr.s_addr = INADDR_ANY; // 接受任意IP地址
    server_addr.sin_port = htons(PORT); // 端口號(hào)轉(zhuǎn)換為網(wǎng)絡(luò)字節(jié)序
 
    // 綁定套接字到指定的IP地址和端口
    if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("綁定失敗");
        close(sockfd);
        exit(EXIT_FAILURE);
    }
 
    printf("UDP服務(wù)器已啟動(dòng)，正在監(jiān)聽端口 %d...\n", PORT);
 
    // 循環(huán)接收數(shù)據(jù)
    while (1) {
        addr_len = sizeof(client_addr);
        // 接收數(shù)據(jù)報(bào)
        n = recvfrom(sockfd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&client_addr, &addr_len);
        if (n < 0) {
            perror("接收數(shù)據(jù)失敗");
            continue;
        }
 
        buffer[n] = '\0'; // 確保字符串以'\0'結(jié)尾
        printf("接收到來自 %s:%d 的消息：%s\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), buffer);
 
        // 發(fā)送響應(yīng)
        const char *response = "服務(wù)器已收到您的消息";
        sendto(sockfd, response, strlen(response), 0, (struct sockaddr *)&client_addr, addr_len);
    }
 
    // 關(guān)閉套接字
    close(sockfd);
    return 0;
}

gcc -o udp_server udp_server.c
./udp_server

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>
 
#define SERVER_PORT 12345
#define SERVER_IP "127.0.0.1"
#define BUFFER_SIZE 1024
 
int main() {
    int sockfd;
    struct sockaddr_in server_addr;
    char buffer[BUFFER_SIZE];
    socklen_t addr_len;
 
    // 創(chuàng)建UDP套接字
    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        perror("創(chuàng)建套接字失敗");
        exit(EXIT_FAILURE);
    }
 
    // 配置服務(wù)器地址
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, SERVER_IP, &server_addr.sin_addr);
 
    // 發(fā)送消息到服務(wù)器
    const char *message = "Hello, UDP Server!";
    sendto(sockfd, message, strlen(message), 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
 
    // 接收服務(wù)器的響應(yīng)
    addr_len = sizeof(server_addr);
    ssize_t n = recvfrom(sockfd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&server_addr, &addr_len);
    if (n > 0) {
        buffer[n] = '\0';
        printf("服務(wù)器響應(yīng)：%s\n", buffer);
    }
 
    // 關(guān)閉套接字
    close(sockfd);
    return 0;
}

gcc -o udp_client udp_client.c
./udp_client