如何利用C语言编写一个高效的UDP通信源码？

UDP（用户数据报协议）是一种无连接的传输层协议，常用于需要快速传输数据但对可靠性要求不高的场景。

UDP服务器端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 1024
int main() {
    int server_sock;
    char message[BUF_SIZE];
    int str_len;
    socklen_t client_addr_size;
    struct sockaddr_in server_addr, client_addr;
    server_sock = socket(PF_INET, SOCK_DGRAM, 0);
    if (server_sock == 1) {
        perror("socket() error");
        exit(1);
    }
    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(12345);
    if (bind(server_sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) == 1) {
        perror("bind() error");
        exit(1);
    }
    while (1) {
        client_addr_size = sizeof(client_addr);
        str_len = recvfrom(server_sock, message, BUF_SIZE, 0, (struct sockaddr *)&client_addr, &client_addr_size);
        sendto(server_sock, message, str_len, 0, (struct sockaddr *)&client_addr, client_addr_size);
    }
    close(server_sock);
    return 0;
}

UDP客户端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 1024
int main() {
    int client_sock;
    char message[BUF_SIZE];
    int str_len;
    socklen_t server_addr_size;
    struct sockaddr_in server_addr, client_addr;
    client_sock = socket(PF_INET, SOCK_DGRAM, 0);
    if (client_sock == 1) {
        perror("socket() error");
        exit(1);
    }
    memset(&client_addr, 0, sizeof(client_addr));
    client_addr.sin_family = AF_INET;
    client_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    client_addr.sin_port = htons(0);
    if (bind(client_sock, (struct sockaddr *)&client_addr, sizeof(client_addr)) == 1) {
        perror("bind() error");
        exit(1);
    }
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_addr.sin_port = htons(12345);
    while (1) {
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);
        if (!strcmp(message, "q
") || !strcmp(message, "Q
")) {
            break;
        }
        sendto(client_sock, message, strlen(message), 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
        server_addr_size = sizeof(server_addr);
        str_len = recvfrom(client_sock, message, BUF_SIZE, 0, (struct sockaddr *)&server_addr, &server_addr_size);
        message[str_len] = 0;
        printf("Message from server: %s", message);
    }
    close(client_sock);
    return 0;
}

这个示例中，服务器端使用UDP协议接收客户端发送的消息，然后将收到的消息原样返回给客户端，客户端从用户输入读取消息并发送给服务器，然后接收服务器返回的消息并打印出来。