?? fig16.17
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#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);}?? 快捷鍵說明
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