linux udp bind

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

#define PORT 8888
#define BUFFER_SIZE 1024

int main() {
    int sockfd;
    struct sockaddr_in servaddr, cliaddr;
    char buffer[BUFFER_SIZE];

    // 创建 UDP 套接字
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket creation failed");
        exit(EXIT_FAILURE);
    }

    memset(&servaddr, 0, sizeof(servaddr));
    memset(&cliaddr, 0, sizeof(cliaddr));

    // 配置服务器地址结构
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = INADDR_ANY;
    servaddr.sin_port = htons(PORT);

    // 绑定套接字到指定端口
    if (bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    printf("UDP Server is up on port %d\n", PORT);

    while (1) {
        socklen_t len = sizeof(cliaddr);
        int n = recvfrom(sockfd, (char *)buffer, BUFFER_SIZE, MSG_WAITALL,
                         (struct sockaddr *)&cliaddr, &len);
        buffer[n] = '\0';
        printf("Client : %s\n", buffer);
        sendto(sockfd, (const char *)buffer, strlen(buffer), MSG_CONFIRM,
               (const struct sockaddr *)&cliaddr, len);
    }

    close(sockfd);
    return 0;
}