10-1timeout.c

#include <stdio.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

#define N 128
#define errlog(errmsg) do{perror(errmsg);\
						  printf("---%s---%s---%d---\n",\
								  __FILE__, __func__, __LINE__);\
						  return -1;\
						 }while(0)
int main(int argc, const char *argv[])
{
	int sockfd;

	struct sockaddr_in serveraddr, clientaddr;
	socklen_t addrlen = sizeof(serveraddr);
	char buf[N] = "";

	/*设置超时时间为5秒*/
	struct timeval t = {5, 0};

	if(argc < 3){
		fprintf(stderr, "Usage: %s ip port\n", argv[0]);
		return -1;
	}

	/*创建套接字*/
	if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0){
		errlog("socket error");
	}

	/*填充网络信息结构体
	 *inet_addr:将点分十进制IP地址转换为网络字节序的整型数据
	 *htons:将主机字节序转换为网络字节序
	 *atoi:将数字型字符串转换为整型数据 
	 */
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
	serveraddr.sin_port = htons(atoi(argv[2]));

	/*将套接字与服务器网络信息结构体绑定*/
	if(bind(sockfd, (struct sockaddr *)&serveraddr, addrlen) < 0){
		errlog("bind error");
	}


	if(setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &t, sizeof(t)) < 0){
		errlog("setsockopt error");
	}

	ssize_t bytes;

	while(1){
		if((bytes = recvfrom(sockfd, buf, N, 0,\
					   (struct sockaddr *)&clientaddr, &addrlen)) < 0){
			errlog("recvfrom error");
		}
		else{
			printf("ip: %s, port: %d\n", 
					inet_ntoa(clientaddr.sin_addr), 
					ntohs(clientaddr.sin_port));

			if(strncmp(buf, "quit", 4) == 0){
				printf("server quit\n");
				break;
			}
			else{
				printf("client: %s\n", buf);

				strcat(buf, "-server");

				if(sendto(sockfd, buf, N, 0,\ 
							(struct sockaddr *)&clientaddr, addrlen) < 0){
					errlog("sendto error");
				}
			}
		}
	}

	close(sockfd);
	return 0;
}