#include "apue.h"#include <netdb.h>#include <errno.h>#include <syslog.h>#include <sys/socket.h>#define BUFLEN		128#define MAXADDRLEN	256#ifndef HOST_NAME_MAX#define HOST_NAME_MAX 256#endifextern int initserver(int, struct sockaddr *, socklen_t, int);voidserve(int sockfd){	int			n;	socklen_t	alen;	FILE		*fp;	char		buf[BUFLEN];	char		abuf[MAXADDRLEN];	for (;;) {		alen = MAXADDRLEN;		if ((n = recvfrom(sockfd, buf, BUFLEN, 0,		  (struct sockaddr *)abuf, &alen)) < 0) {			syslog(LOG_ERR, "ruptimed: recvfrom error: %s",			  strerror(errno));			exit(1);		}		if ((fp = popen("/usr/bin/uptime", "r")) == NULL) {			sprintf(buf, "error: %s\n", strerror(errno));			sendto(sockfd, buf, strlen(buf), 0,			  (struct sockaddr *)abuf, alen);		} else {			if (fgets(buf, BUFLEN, fp) != NULL)				sendto(sockfd, buf, strlen(buf), 0,				  (struct sockaddr *)abuf, alen);			pclose(fp);		}	}}intmain(int argc, char *argv[]){	struct addrinfo	*ailist, *aip;	struct addrinfo	hint;	int				sockfd, err, n;	char			*host;	if (argc != 1)		err_quit("usage: ruptimed");#ifdef _SC_HOST_NAME_MAX	n = sysconf(_SC_HOST_NAME_MAX);	if (n < 0)	/* best guess */#endif		n = HOST_NAME_MAX;	host = malloc(n);	if (host == NULL)		err_sys("malloc error");	if (gethostname(host, n) < 0)		err_sys("gethostname error");	daemonize("ruptimed");	hint.ai_flags = AI_CANONNAME;	hint.ai_family = 0;	hint.ai_socktype = SOCK_DGRAM;	hint.ai_protocol = 0;	hint.ai_addrlen = 0;	hint.ai_canonname = NULL;	hint.ai_addr = NULL;	hint.ai_next = NULL;	if ((err = getaddrinfo(host, "ruptime", &hint, &ailist)) != 0) {		syslog(LOG_ERR, "ruptimed: getaddrinfo error: %s",		  gai_strerror(err));		exit(1);	}	for (aip = ailist; aip != NULL; aip = aip->ai_next) {		if ((sockfd = initserver(SOCK_DGRAM, aip->ai_addr,		  aip->ai_addrlen, 0)) >= 0) {			serve(sockfd);			exit(0);		}	}	exit(1);}