void dg_cli(FILE *fp, int sockfd, const struct sockaddr * pservaddr, socklen_t servlen) {
	int n;
	char sendline[maxline], recvline[maxline+1];
	char errbuff[maxline];
	struct sockaddr_in localaddr;
	socklen_t len=sizeof(localaddr);

	if(connect(sockfd, (struct sockaddr *)pservaddr, servlen)<0) {
		strerror_r(errno, errbuff, maxline);
		fprintf(stderr, "connect error: %s\n", errbuff);
		exit(-1);
	}

	while(fgets(sendline, maxline, fp) != NULL) {
		if((n=write(sockfd, sendline, strlen(sendline)))<0) {
			strerror_r(errno, errbuff, maxline);
			fprintf(stderr, "write error: %s\n", errbuff);
			exit(-1);
		}

		if(read(sockfd, recvline, maxline) != n) {
			strerror_r(errno, errbuff, maxline);
			fprintf(stderr, "read error: %s\n", errbuff);
			exit(-1);
		}
		if(getsockname(sockfd, (struct sockaddr *)&localaddr, &len)<0) {
			strerror_r(errno, errbuff, maxline);
			fprintf(stderr, "getsockname error: %s\n", errbuff);
			exit(-1);
		}
		recvline[n]=0;
		fputs(recvline, stdout);
		printf("local ip: %s, local port: %d\n", inet_ntop(AF_INET, &localaddr.sin_addr, errbuff, sizeof(errbuff)), ntohs(localaddr.sin_port));		
	}
}