linux网络编程udp

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

#define PORT 8080
#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));

    // 填充服务器信息
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = INADDR_ANY;
    servaddr.sin_port = htons(PORT);

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

    int len, n;
    while (1) {
        len = sizeof(cliaddr); // len是值-结果参数
        n = recvfrom(sockfd, (char *)buffer, BUFFER_SIZE, 0, (struct sockaddr *)&cliaddr, &len);
        buffer[n] = '\0';
        printf("Server received message: %s\n", buffer);

        // 发送响应
        sendto(sockfd, (const char *)buffer, n, 0, (const struct sockaddr *)&cliaddr, len);
    }

    close(sockfd);
    return 0;
}

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

#define PORT 8080
#define BUFFER_SIZE 1024

int main() {
    int sockfd;
    struct sockaddr_in servaddr;
    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));

    // 填充服务器信息
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);

    if (inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr) <= 0) {
        perror("inet_pton");
        exit(EXIT_FAILURE);
    }

    while (1) {
        printf("Enter message: ");
        fgets(buffer, BUFFER_SIZE, stdin);
        buffer[strcspn(buffer, "\n")] = 0; // 去掉换行符

        // 发送数据
        sendto(sockfd, (const char *)buffer, strlen(buffer), 0, (const struct sockaddr *)&servaddr, sizeof(servaddr));

        // 接收响应
        int len = sizeof(servaddr);
        recvfrom(sockfd, (char *)buffer, BUFFER_SIZE, 0, (struct sockaddr *)&servaddr, &len);
        buffer[len] = '\0';
        printf("Server response: %s\n", buffer);
    }

    close(sockfd);
    return 0;
}