udp_echo_server.c

// 基于未连接udp套接字的回声服务端

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

#include "error_handling.h"

#define BUF_SIZE 30

int main(int argc, char *argv[])
{
	int serv_sock;
	char message[BUF_SIZE];
	int str_len;
	socklen_t clnt_adr_sz;

	struct sockaddr_in serv_adr, clnt_adr;
	if (argc != 2)
	{
		printf("Usage: %s <port>\n", argv[0]);
		exit(1);
	}

	serv_sock = socket(PF_INET, SOCK_DGRAM, 0);
	if (serv_sock == -1)
	{
		error_handling("socket() error: %s", strerror(errno));
	}
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_adr.sin_port = htons(atoi(argv[1]));

	if (bind(serv_sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) == -1)
	{
		error_handling("bind() error: %s", strerror(errno));
	}

	while (1)
	{
		clnt_adr_sz = sizeof(clnt_adr);
		str_len = recvfrom(serv_sock, message, BUF_SIZE, 0, (struct sockaddr *)&clnt_adr, &clnt_adr_sz);
		printf("receive %s from client: %s:%d, len: %d\n", message, inet_ntoa(clnt_adr.sin_addr), ntohs(clnt_adr.sin_port), str_len);
		sendto(serv_sock, message, str_len, 0, (struct sockaddr *)&clnt_adr, clnt_adr_sz);
	}
	close(serv_sock);
	return 0;
}