Unix网络编程代码 第13章 守护进程和inetd超级服务器

第13章 守护进程和inetd超级服务器

13.4 daemon_init函数

13.4.1 作为守护进程运行的协议无关时间获取服务器程序

运行: ./server localhost daytime

查看日志: tail /var/log/syslog

#define _POSIX_SOURCE
#include	<time.h>
#include	<strings.h>
#include	<sys/socket.h>	/* basic socket definitions */
#include	<errno.h>
#include	<string.h>
#include	<unistd.h>
#include	<stdio.h>
#include	<stdlib.h>
#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<stdarg.h>	/* ANSI C header file */
#include	<netdb.h>
#include	<arpa/inet.h>
#include	<sys/un.h>
#include	<syslog.h>
#include	<signal.h>
#include	<fcntl.h>	/* for nonblocking */
typedef void Sigfunc(int);	/* for signal handlers */
#define	MAXFD	64
#define	MAXLINE		4096	/* max text line length */
#define	LISTENQ		1024	/* 2nd argument to listen() */
#define	SA	struct sockaddr
#define IPV6
int daemon_proc;		/* set nonzero by daemon_init() */
void err_doit(int errnoflag, int level, const char *fmt, va_list ap)
{
	int errno_save, n;
	char buf[MAXLINE + 1];

	errno_save = errno;	/* value caller might want printed */
#ifdef	HAVE_VSNPRINTF
	vsnprintf(buf, MAXLINE, fmt, ap);	/* safe */
#else
	vsprintf(buf, fmt, ap);	/* not safe */
#endif
	n = strlen(buf);
	if (errnoflag)
		snprintf(buf + n, MAXLINE - n, ": %s", strerror(errno_save));
	strcat(buf, "\n");

	if (daemon_proc) {
		syslog(level, "%s", buf);
	} else {
		fflush(stdout);	/* in case stdout and stderr are the same */
		fputs(buf, stderr);
		fflush(stderr);
	}
	return;
}

void err_msg(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	err_doit(0, LOG_INFO, fmt, ap);
	va_end(ap);
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	err_doit(0, LOG_ERR, fmt, ap);
	va_end(ap);
	exit(1);
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	err_doit(1, LOG_ERR, fmt, ap);
	va_end(ap);
	exit(1);
}

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Close(int fd)
{
	if (close(fd) == -1)
		err_sys("close error");
}

void Listen(int fd, int backlog)
{
	char *ptr;

	/*4can override 2nd argument with environment variable */
	if ((ptr = getenv("LISTENQ")) != NULL)
		backlog = atoi(ptr);

	if (listen(fd, backlog) < 0)
		err_sys("listen error");
}

int Accept(int fd, struct sockaddr *sa, socklen_t * salenptr)
{
	int n;

 again:if ((n = accept(fd, sa, salenptr)) < 0) {
#ifdef	EPROTO
		if (errno == EPROTO || errno == ECONNABORTED)
#else
		if (errno == ECONNABORTED)
#endif
			goto again;
		else
			err_sys("accept error");
	}
	return (n);
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (bind(fd, sa, salen) < 0)
		err_sys("bind error");
}

void Write(int fd, void *ptr, int nbytes)
{
	if (write(fd, ptr, nbytes) != nbytes)
		err_sys("write error");
}

void Setsockopt(int fd, int level, int optname, const void *optval,
		socklen_t optlen)
{
	if (setsockopt(fd, level, optname, optval, optlen) < 0)
		err_sys("setsockopt error");
}

int tcp_listen(const char *host, const char *serv, socklen_t * addrlenp)
{
	int listenfd, n;
	const int on = 1;
	struct addrinfo hints, *res, *ressave;

	bzero(&hints, sizeof(struct addrinfo));
	hints.ai_flags = AI_PASSIVE;
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;

	if ((n = getaddrinfo(host, serv, &hints, &res)) != 0)
		err_quit("tcp_listen error for %s, %s: %s",
			 host, serv, gai_strerror(n));
	ressave = res;

	do {
		listenfd =
		    socket(res->ai_family, res->ai_socktype, res->ai_protocol);
		if (listenfd < 0)
			continue;	/* error, try next one */

		Setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
		if (bind(listenfd, res->ai_addr, res->ai_addrlen) == 0)
			break;	/* success */

		Close(listenfd);	/* bind error, close and try next one */
	} while ((res = res->ai_next) != NULL);

	if (res == NULL)	/* errno from final socket() or bind() */
		err_sys("tcp_listen error for %s, %s", host, serv);

	Listen(listenfd, LISTENQ);

	if (addrlenp)
		*addrlenp = res->ai_addrlen;	/* return size of protocol address */

	freeaddrinfo(ressave);

	return (listenfd);
}

int Tcp_listen(const char *host, const char *serv, socklen_t * addrlenp)
{
	return (tcp_listen(host, serv, addrlenp));
}

char *sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char portstr[8];
	static char str[128];	/* Unix domain is largest */

	switch (sa->sa_family) {
	case AF_INET:{
			struct sockaddr_in *sin = (struct sockaddr_in *)sa;

			if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str))
			    == NULL)
				return (NULL);
			if (ntohs(sin->sin_port) != 0) {
				snprintf(portstr, sizeof(portstr), ":%d",
					 ntohs(sin->sin_port));
				strcat(str, portstr);
			}
			return (str);
		}
		/* end sock_ntop */

#ifdef	IPV6
	case AF_INET6:{
			struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;

			str[0] = '[';
			if (inet_ntop
			    (AF_INET6, &sin6->sin6_addr, str + 1,
			     sizeof(str) - 1) == NULL)
				return (NULL);
			if (ntohs(sin6->sin6_port) != 0) {
				snprintf(portstr, sizeof(portstr), "]:%d",
					 ntohs(sin6->sin6_port));
				strcat(str, portstr);
				return (str);
			}
			return (str + 1);
		}
#endif

#ifdef	AF_UNIX
	case AF_UNIX:{
			struct sockaddr_un *unp = (struct sockaddr_un *)sa;

			/* OK to have no pathname bound to the socket: happens on
			   every connect() unless client calls bind() first. */
			if (unp->sun_path[0] == 0)
				strcpy(str, "(no pathname bound)");
			else
				snprintf(str, sizeof(str), "%s", unp->sun_path);
			return (str);
		}
#endif

#ifdef	HAVE_SOCKADDR_DL_STRUCT
	case AF_LINK:{
			struct sockaddr_dl *sdl = (struct sockaddr_dl *)sa;

			if (sdl->sdl_nlen > 0)
				snprintf(str, sizeof(str), "%*s (index %d)",
					 sdl->sdl_nlen, &sdl->sdl_data[0],
					 sdl->sdl_index);
			else
				snprintf(str, sizeof(str), "AF_LINK, index=%d",
					 sdl->sdl_index);
			return (str);
		}
#endif
	default:
		snprintf(str, sizeof(str),
			 "sock_ntop: unknown AF_xxx: %d, len %d", sa->sa_family,
			 salen);
		return (str);
	}
	return (NULL);
}

char *Sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char *ptr;

	if ((ptr = sock_ntop(sa, salen)) == NULL)
		err_sys("sock_ntop error");	/* inet_ntop() sets errno */
	return (ptr);
}

Sigfunc *signal(int signo, Sigfunc * func)
{
	struct sigaction act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	if (signo == SIGALRM) {
#ifdef	SA_INTERRUPT
		act.sa_flags |= SA_INTERRUPT;	/* SunOS 4.x */
#endif
	} else {
#ifdef	SA_RESTART
		act.sa_flags |= SA_RESTART;	/* SVR4, 44BSD */
#endif
	}
	if (sigaction(signo, &act, &oact) < 0)
		return (SIG_ERR);
	return (oact.sa_handler);
}


Sigfunc *Signal(int signo, Sigfunc * func)
{				/* for our signal() function */
	Sigfunc *sigfunc;

	if ((sigfunc = signal(signo, func)) == SIG_ERR)
		err_sys("signal error");
	return (sigfunc);
}

pid_t Fork(void)
{
	pid_t pid;

	if ((pid = fork()) == -1)
		err_sys("fork error");
	return (pid);
}

int daemon_init(const char *pname, int facility)
{
	int i;
	pid_t pid;

	if ((pid = Fork()) < 0)
		return (-1);
	else if (pid)
		_exit(0);	/* parent terminates */

	/* child 1 continues... */

	if (setsid() < 0)	/* become session leader */
		return (-1);

	Signal(SIGHUP, SIG_IGN);
	if ((pid = Fork()) < 0)
		return (-1);
	else if (pid)
		_exit(0);	/* child 1 terminates */

	/* child 2 continues... */

	daemon_proc = 1;	/* for err_XXX() functions */

	chdir("/");		/* change working directory */

	/* close off file descriptors */
	for (i = 0; i < MAXFD; i++)
		close(i);

	/* redirect stdin, stdout, and stderr to /dev/null */
	open("/dev/null", O_RDONLY);
	open("/dev/null", O_RDWR);
	open("/dev/null", O_RDWR);

	openlog(pname, LOG_PID, facility);

	return (0);		/* success */
}

void *Malloc(size_t size)
{
	void *ptr;

	if ((ptr = malloc(size)) == NULL)
		err_sys("malloc error");
	return (ptr);
}

int main(int argc, char **argv)
{
	int listenfd, connfd;
	socklen_t addrlen, len;
	struct sockaddr *cliaddr;
	char buff[MAXLINE];
	time_t ticks;

	if (argc < 2 || argc > 3)
		err_quit("usage: daytimetcpsrv2 [ <host> ] <service or port>");

	daemon_init(argv[0], 0);

	if (argc == 2)
		listenfd = Tcp_listen(NULL, argv[1], &addrlen);
	else
		listenfd = Tcp_listen(argv[1], argv[2], &addrlen);

	cliaddr = (struct sockaddr *)Malloc(addrlen);

	for (;;) {
		len = addrlen;
		connfd = Accept(listenfd, cliaddr, &len);
		err_msg("connection from %s", Sock_ntop(cliaddr, len));

		ticks = time(NULL);
		snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
		Write(connfd, buff, strlen(buff));

		Close(connfd);
	}
}

13.6 daemon_inetd函数

要运行这个例子程序，

1.先要添加服务:做法,在/etc/services最后加上: mydaytime 9999/tcp

2.安装xinetd: sudo apt-get install xinetd

3.编辑配置:在/etc/xinetd.d/目录下新建一个mydaytime文件,内容如下:

service mydaytime
{
socket_type = stream
protocol = tcp
wait = no
user =root
server =/home/xpmo/unp/server
}
 其中server是例子程序的路径

4.重启xinetdsudo killall -HUP xinetd

5.查看启动成功否：

sudo netstat -tlp

如果看到mydaytime就说明启动成功了。

例子代码:

#include	<time.h>
#include	<sys/socket.h>	/* basic socket definitions */
#include	<errno.h>
#include	<string.h>
#include	<unistd.h>
#include	<stdio.h>
#include	<stdlib.h>
#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<stdarg.h>	/* ANSI C header file */
#include	<arpa/inet.h>
#include	<sys/un.h>
#include	<syslog.h>
#define	MAXLINE		4096	/* max text line length */
#define IPV6
int daemon_proc;		/* set nonzero by daemon_init() */
void err_doit(int errnoflag, int level, const char *fmt, va_list ap)
{
	int errno_save, n;
	char buf[MAXLINE + 1];

	errno_save = errno;	/* value caller might want printed */
#ifdef	HAVE_VSNPRINTF
	vsnprintf(buf, MAXLINE, fmt, ap);	/* safe */
#else
	vsprintf(buf, fmt, ap);	/* not safe */
#endif
	n = strlen(buf);
	if (errnoflag)
		snprintf(buf + n, MAXLINE - n, ": %s", strerror(errno_save));
	strcat(buf, "\n");

	if (daemon_proc) {
		syslog(level, "%s", buf);
	} else {
		fflush(stdout);	/* in case stdout and stderr are the same */
		fputs(buf, stderr);
		fflush(stderr);
	}
	return;
}

void err_msg(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	err_doit(0, LOG_INFO, fmt, ap);
	va_end(ap);
	return;
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	err_doit(1, LOG_ERR, fmt, ap);
	va_end(ap);
	exit(1);
}

void Close(int fd)
{
	if (close(fd) == -1)
		err_sys("close error");
}

void Write(int fd, void *ptr, int nbytes)
{
	if (write(fd, ptr, nbytes) != nbytes)
		err_sys("write error");
}

void Setsockopt(int fd, int level, int optname, const void *optval,
		socklen_t optlen)
{
	if (setsockopt(fd, level, optname, optval, optlen) < 0)
		err_sys("setsockopt error");
}

char *sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char portstr[8];
	static char str[128];	/* Unix domain is largest */

	switch (sa->sa_family) {
	case AF_INET:{
			struct sockaddr_in *sin = (struct sockaddr_in *)sa;

			if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str))
			    == NULL)
				return (NULL);
			if (ntohs(sin->sin_port) != 0) {
				snprintf(portstr, sizeof(portstr), ":%d",
					 ntohs(sin->sin_port));
				strcat(str, portstr);
			}
			return (str);
		}
		/* end sock_ntop */

#ifdef	IPV6
	case AF_INET6:{
			struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;

			str[0] = '[';
			if (inet_ntop
			    (AF_INET6, &sin6->sin6_addr, str + 1,
			     sizeof(str) - 1) == NULL)
				return (NULL);
			if (ntohs(sin6->sin6_port) != 0) {
				snprintf(portstr, sizeof(portstr), "]:%d",
					 ntohs(sin6->sin6_port));
				strcat(str, portstr);
				return (str);
			}
			return (str + 1);
		}
#endif

#ifdef	AF_UNIX
	case AF_UNIX:{
			struct sockaddr_un *unp = (struct sockaddr_un *)sa;

			/* OK to have no pathname bound to the socket: happens on
			   every connect() unless client calls bind() first. */
			if (unp->sun_path[0] == 0)
				strcpy(str, "(no pathname bound)");
			else
				snprintf(str, sizeof(str), "%s", unp->sun_path);
			return (str);
		}
#endif

#ifdef	HAVE_SOCKADDR_DL_STRUCT
	case AF_LINK:{
			struct sockaddr_dl *sdl = (struct sockaddr_dl *)sa;

			if (sdl->sdl_nlen > 0)
				snprintf(str, sizeof(str), "%*s (index %d)",
					 sdl->sdl_nlen, &sdl->sdl_data[0],
					 sdl->sdl_index);
			else
				snprintf(str, sizeof(str), "AF_LINK, index=%d",
					 sdl->sdl_index);
			return (str);
		}
#endif
	default:
		snprintf(str, sizeof(str),
			 "sock_ntop: unknown AF_xxx: %d, len %d", sa->sa_family,
			 salen);
		return (str);
	}
	return (NULL);
}

char *Sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char *ptr;

	if ((ptr = sock_ntop(sa, salen)) == NULL)
		err_sys("sock_ntop error");	/* inet_ntop() sets errno */
	return (ptr);
}

void *Malloc(size_t size)
{
	void *ptr;

	if ((ptr = malloc(size)) == NULL)
		err_sys("malloc error");
	return (ptr);
}

void daemon_inetd(const char *pname, int facility)
{
	daemon_proc = 1;	/* for our err_XXX() functions */
	openlog(pname, LOG_PID, facility);
}

void Getpeername(int fd, struct sockaddr *sa, socklen_t * salenptr)
{
	if (getpeername(fd, sa, salenptr) < 0)
		err_sys("getpeername error");
}

int main(int argc, char **argv)
{
	socklen_t len;
	struct sockaddr *cliaddr;
	char buff[MAXLINE];
	time_t ticks;

	daemon_inetd(argv[0], 0);

	cliaddr = (struct sockaddr *)Malloc(sizeof(struct sockaddr_storage));
	len = sizeof(struct sockaddr_storage);
	Getpeername(0, cliaddr, &len);
	err_msg("connection from %s", Sock_ntop(cliaddr, len));

	ticks = time(NULL);
	snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
	Write(0, buff, strlen(buff));

	Close(0);		/* close TCP connection */
	exit(0);
}