syslogd.c

linux下记录系统日志代码以及记录内核日志代码

{
	register char *p, *q;
	register int c;
	char line[MAXLINE + 1];
	int pri, flags;
	char *lp;

	(void) snprintf(line, sizeof(line), "vmunix: ");
	lp = line + strlen(line);
	for (p = msg; *p != '\0'; ) {
		flags = ADDDATE;
		pri = DEFSPRI;
		if (*p == '<') {
			pri = 0;
			while (isdigit(*++p))
				pri = 10 * pri + (*p - '0');
			if (*p == '>')
				++p;
		} else {
			/* kernel printf's come out on console */
			flags |= IGN_CONS;
		}
		if (pri &~ (LOG_FACMASK|LOG_PRIMASK))
			pri = DEFSPRI;
		q = lp;
		while (*p != '\0' && (c = *p++) != '\n' &&
		    q < &line[MAXLINE])
			*q++ = c;
		*q = '\0';
		logmsg(pri, line, LocalHostName, flags);
	}
	return;
}

/*
 * Decode a priority into textual information like auth.emerg.
 */
char *textpri(pri)
	int pri;
{
	static char res[20];
	CODE *c_pri, *c_fac;

	for (c_fac = facilitynames; c_fac->c_name && !(c_fac->c_val == LOG_FAC(pri)<<3); c_fac++);
	for (c_pri = prioritynames; c_pri->c_name && !(c_pri->c_val == LOG_PRI(pri)); c_pri++);

	snprintf (res, sizeof(res), "%s.%s<%d>", c_fac->c_name, c_pri->c_name, pri);

	return res;
}

time_t	now;

/*
 * Log a message to the appropriate log files, users, etc. based on
 * the priority.
 */

void logmsg(pri, msg, from, flags)
	int pri;
	char *msg;
	const char *from;
	int flags;
{
	register struct filed *f;
	int fac, prilev, lognum;
	int msglen;
	char *timestamp;

	dprintf("logmsg: %s, flags %x, from %s, msg %s\n", textpri(pri), flags, from, msg);

#ifndef SYSV
	omask = sigblock(sigmask(SIGHUP)|sigmask(SIGALRM));
#endif

	/*
	 * Check to see if msg looks non-standard.
	 */
	msglen = strlen(msg);
	if (msglen < 16 || msg[3] != ' ' || msg[6] != ' ' ||
	    msg[9] != ':' || msg[12] != ':' || msg[15] != ' ')
		flags |= ADDDATE;

	(void) time(&now);
	if (flags & ADDDATE)
		timestamp = ctime(&now) + 4;
	else {
		timestamp = msg;
		msg += 16;
		msglen -= 16;
	}

	/* extract facility and priority level */
	if (flags & MARK)
		fac = LOG_NFACILITIES;
	else
		fac = LOG_FAC(pri);
	prilev = LOG_PRI(pri);

	/* log the message to the particular outputs */
	if (!Initialized) {
		f = &consfile;
		f->f_file = open(ctty, O_WRONLY|O_NOCTTY);

		if (f->f_file >= 0) {
			untty();
			fprintlog(f, (char *)from, flags, msg);
			(void) close(f->f_file);
			f->f_file = -1;
		}
#ifndef SYSV
		(void) sigsetmask(omask);
#endif
		return;
	}
#ifdef SYSV
	for (lognum = 0; lognum <= nlogs; lognum++) {
		f = &Files[lognum];
#else
	for (f = Files; f; f = f->f_next) {
#endif

		/* skip messages that are incorrect priority */
		if ( (f->f_pmask[fac] == TABLE_NOPRI) || \
		    ((f->f_pmask[fac] & (1<<prilev)) == 0) )
		  	continue;

		if (f->f_type == F_CONSOLE && (flags & IGN_CONS))
			continue;

		/* don't output marks to recently written files */
		if ((flags & MARK) && (now - f->f_time) < MarkInterval / 2)
			continue;

		/*
		 * suppress duplicate lines to this file
		 */
		if ((flags & MARK) == 0 && msglen == f->f_prevlen &&
		    !strcmp(msg, f->f_prevline) &&
		    !strcmp(from, f->f_prevhost)) {
			(void) strncpy(f->f_lasttime, timestamp, 15);
			f->f_prevcount++;
			dprintf("msg repeated %d times, %ld sec of %d.\n",
			    f->f_prevcount, now - f->f_time,
			    repeatinterval[f->f_repeatcount]);
			/*
			 * If domark would have logged this by now,
			 * flush it now (so we don't hold isolated messages),
			 * but back off so we'll flush less often
			 * in the future.
			 */
			if (now > REPEATTIME(f)) {
				fprintlog(f, (char *)from, flags, (char *)NULL);
				BACKOFF(f);
			}
		} else {
			/* new line, save it */
			if (f->f_prevcount)
				fprintlog(f, (char *)from, 0, (char *)NULL);
			f->f_prevpri = pri;
			f->f_repeatcount = 0;
			(void) strncpy(f->f_lasttime, timestamp, 15);
			(void) strncpy(f->f_prevhost, from,
					sizeof(f->f_prevhost));
			if (msglen < MAXSVLINE) {
				f->f_prevlen = msglen;
				(void) strcpy(f->f_prevline, msg);
				fprintlog(f, (char *)from, flags, (char *)NULL);
			} else {
				f->f_prevline[0] = 0;
				f->f_prevlen = 0;
				fprintlog(f, (char *)from, flags, msg);
			}
		}
	}
#ifndef SYSV
	(void) sigsetmask(omask);
#endif
}
#if FALSE
} /* balance parentheses for emacs */
#endif

void fprintlog(f, from, flags, msg)
	register struct filed *f;
	char *from;
	int flags;
	char *msg;
{
	struct iovec iov[3];
	register struct iovec *v = iov;
	char repbuf[80];
#ifdef SYSLOG_INET
	register int l;
	char line[MAXLINE + 1];
	time_t fwd_suspend;
	struct hostent *hp;
#endif

	dprintf("Called fprintlog, ");
       /*
	v->iov_base = f->f_lasttime;
	v->iov_len = 15;
	v++;
	v->iov_base = " ";
	v->iov_len = 1;
	v++;
	v->iov_base = f->f_prevhost;
	v->iov_len = strlen(v->iov_base);
	v++;
	*/	
	v->iov_base = "";
	v->iov_len = 0;
	v++;
      
	if (msg) {
		v->iov_base = msg;
		v->iov_len = strlen(msg);
	} else if (f->f_prevcount > 1) {
		(void) snprintf(repbuf, sizeof(repbuf), "last message repeated %d times",
		    f->f_prevcount);
		v->iov_base = repbuf;
		v->iov_len = strlen(repbuf);
	} else {
		v->iov_base = f->f_prevline;
		v->iov_len = f->f_prevlen;
	}
	v++;

	dprintf("logging to %s", TypeNames[f->f_type]);

	switch (f->f_type) {
	case F_UNUSED:
		f->f_time = now;
		dprintf("\n");
		break;

#ifdef SYSLOG_INET
	case F_FORW_SUSP:
		fwd_suspend = time((time_t *) 0) - f->f_time;
		if ( fwd_suspend >= INET_SUSPEND_TIME ) {
			dprintf("\nForwarding suspension over, " \
				"retrying FORW ");
			f->f_type = F_FORW;
			goto f_forw;
		}
		else {
			dprintf(" %s\n", f->f_un.f_forw.f_hname);
			dprintf("Forwarding suspension not over, time " \
				"left: %d.\n", INET_SUSPEND_TIME - \
				fwd_suspend);
		}
		break;
		
	/*
	 * The trick is to wait some time, then retry to get the
	 * address. If that fails retry x times and then give up.
	 *
	 * You'll run into this problem mostly if the name server you
	 * need for resolving the address is on the same machine, but
	 * is started after syslogd. 
	 */
	case F_FORW_UNKN:
		dprintf(" %s\n", f->f_un.f_forw.f_hname);
		fwd_suspend = time((time_t *) 0) - f->f_time;
		if ( fwd_suspend >= INET_SUSPEND_TIME ) {
			dprintf("Forwarding suspension to unknown over, retrying\n");
			if ( (hp = gethostbyname(f->f_un.f_forw.f_hname)) == NULL ) {
				dprintf("Failure: %s\n", sys_h_errlist[h_errno]);
				dprintf("Retries: %d\n", f->f_prevcount);
				if ( --f->f_prevcount < 0 ) {
					dprintf("Giving up.\n");
					f->f_type = F_UNUSED;
				}
				else
					dprintf("Left retries: %d\n", f->f_prevcount);
			}
			else {
			        dprintf("%s found, resuming.\n", f->f_un.f_forw.f_hname);
				memcpy((char *) &f->f_un.f_forw.f_addr.sin_addr, hp->h_addr, hp->h_length);
				f->f_prevcount = 0;
				f->f_type = F_FORW;
				goto f_forw;
			}
		}
		else
			dprintf("Forwarding suspension not over, time " \
				"left: %d\n", INET_SUSPEND_TIME - fwd_suspend);
		break;

	case F_FORW:
		/* 
		 * Don't send any message to a remote host if it
		 * already comes from one. (we don't care 'bout who
		 * sent the message, we don't send it anyway)  -Joey
		 */
	f_forw:
		dprintf(" %s\n", f->f_un.f_forw.f_hname);
		if ( strcmp(from, LocalHostName) && NoHops )
			dprintf("Not sending message to remote.\n");
		else {
			f->f_time = now;
			(void) snprintf(line, sizeof(line), "<%d>%s\n", f->f_prevpri, \
				(char *) iov[4].iov_base);
			l = strlen(line);
			if (l > MAXLINE)
				l = MAXLINE;
			if (sendto(finet, line, l, 0, \
				   (struct sockaddr *) &f->f_un.f_forw.f_addr,
				   sizeof(f->f_un.f_forw.f_addr)) != l) {
				int e = errno;
				dprintf("INET sendto error: %d = %s.\n", 
					e, strerror(e));
				f->f_type = F_FORW_SUSP;
				errno = e;
				logerror("sendto");
			}
		}
		break;
#endif

	case F_CONSOLE:
		f->f_time = now;
#ifdef UNIXPC
		if (1) {
#else
		if (flags & IGN_CONS) {	
#endif
			dprintf(" (ignored).\n");
			break;
		}
		/* FALLTHROUGH */

	case F_TTY:
	case F_FILE:
	case F_PIPE:
		f->f_time = now;
		dprintf(" %s\n", f->f_un.f_fname);
		if (f->f_type == F_TTY || f->f_type == F_CONSOLE) {
			v->iov_base = "\r\n";
			v->iov_len = 2;
		} else {
			v->iov_base = "\n";
			v->iov_len = 1;
		}
	again:
		/* f->f_file == -1 is an indicator that the we couldn't
		   open the file at startup. */
		if (f->f_file == -1)
			break;

		if (writev(f->f_file, iov, 3) < 0) {
			int e = errno;

			/* If a named pipe is full, just ignore it for now
			   - mrn 24 May 96 */
			if (f->f_type == F_PIPE && e == EAGAIN)
				break;

			(void) close(f->f_file);
			/*
			 * Check for EBADF on TTY's due to vhangup() XXX
			 * Linux uses EIO instead (mrn 12 May 96)
			 */
			if ((f->f_type == F_TTY || f->f_type == F_CONSOLE)
#ifdef linux
				&& e == EIO) {
#else
				&& e == EBADF) {
#endif
				f->f_file = open(f->f_un.f_fname, O_WRONLY|O_APPEND|O_NOCTTY);
				if (f->f_file < 0) {
					f->f_type = F_UNUSED;
					logerror(f->f_un.f_fname);
				} else {
					untty();
					goto again;
				}
			} else {
				f->f_type = F_UNUSED;
				errno = e;
				logerror(f->f_un.f_fname);
			}
		} else if (f->f_flags & SYNC_FILE)
			(void) fsync(f->f_file);
		break;

	case F_USERS:
	case F_WALL:
		f->f_time = now;
		dprintf("\n");
		v->iov_base = "\r\n";
		v->iov_len = 2;
		wallmsg(f, iov);
		break;
	} /* switch */
	if (f->f_type != F_FORW_UNKN)
		f->f_prevcount = 0;
	return;		
}
#if FALSE
}} /* balance parentheses for emacs */
#endif

jmp_buf ttybuf;

void endtty()
{
	longjmp(ttybuf, 1);
}

/*
 *  WALLMSG -- Write a message to the world at large
 *
 *	Write the specified message to either the entire
 *	world, or a list of approved users.
 */

void wallmsg(f, iov)
	register struct filed *f;
	struct iovec *iov;
{
	char p[6 + UNAMESZ];
	register int i;
	int ttyf, len;
	static int reenter = 0;
	struct utmp ut;
	struct utmp *uptr;
	char greetings[200];

	if (reenter++)
		return;

	/* open the user login file */
	setutent();


	/*
	 * Might as well fork instead of using nonblocking I/O
	 * and doing notty().
	 */
	if (fork() == 0) {
		(void) signal(SIGTERM, SIG_DFL);
		(void) alarm(0);
		(void) signal(SIGALRM, endtty);
#ifndef SYSV
		(void) signal(SIGTTOU, SIG_IGN);
		(void) sigsetmask(0);
#endif
		(void) snprintf(greetings, sizeof(greetings),
		    "\r\n\7Message from syslogd@%s at %.24s ...\r\n",
			(char *) iov[2].iov_base, ctime(&now));
		len = strlen(greetings);

		/* scan the user login file */
		while ((uptr = getutent())) {
			memcpy(&ut, uptr, sizeof(ut));
			/* is this slot used? */
			if (ut.ut_name[0] == '\0')
				continue;
			if (ut.ut_type == LOGIN_PROCESS)
			        continue;
			if (!(strcmp (ut.ut_name,"LOGIN"))) /* paranoia */
			        continue;

			/* should we send the message to this user? */
			if (f->f_type == F_USERS) {
				for (i = 0; i < MAXUNAMES; i++) {
					if (!f->f_un.f_uname[i][0]) {
						i = MAXUNAMES;
						break;
					}
					if (strncmp(f->f_un.f_uname[i],
					    ut.ut_name, UNAMESZ) == 0)
						break;
				}
				if (i >= MAXUNAMES)
					continue;
			}

			/* compute the device name */
			strcpy(p, _PATH_DEV);
			strncat(p, ut.ut_line, UNAMESZ);

			if (f->f_type == F_WALL) {
				iov[0].iov_base = greetings;
				iov[0].iov_len = len;
				iov[1].iov_len = 0;
			}
			if (setjmp(ttybuf) == 0) {
				(void) alarm(15);