syslogd.c

早期freebsd实现

/*
 * Copyright (c) 1983, 1988, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1983, 1988, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)syslogd.c	8.3 (Berkeley) 4/4/94";
#endif /* not lint */

/*
 *  syslogd -- log system messages
 *
 * This program implements a system log. It takes a series of lines.
 * Each line may have a priority, signified as "<n>" as
 * the first characters of the line.  If this is
 * not present, a default priority is used.
 *
 * To kill syslogd, send a signal 15 (terminate).  A signal 1 (hup) will
 * cause it to reread its configuration file.
 *
 * Defined Constants:
 *
 * MAXLINE -- the maximimum line length that can be handled.
 * DEFUPRI -- the default priority for user messages
 * DEFSPRI -- the default priority for kernel messages
 *
 * Author: Eric Allman
 * extensive changes by Ralph Campbell
 * more extensive changes by Eric Allman (again)
 */

#define	MAXLINE		1024		/* maximum line length */
#define	MAXSVLINE	120		/* maximum saved line length */
#define DEFUPRI		(LOG_USER|LOG_NOTICE)
#define DEFSPRI		(LOG_KERN|LOG_CRIT)
#define TIMERINTVL	30		/* interval for checking flush, mark */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/msgbuf.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>
#include "pathnames.h"

#define SYSLOG_NAMES
#include <sys/syslog.h>

char	*LogName = _PATH_LOG;
char	*ConfFile = _PATH_LOGCONF;
char	*PidFile = _PATH_LOGPID;
char	ctty[] = _PATH_CONSOLE;

#define FDMASK(fd)	(1 << (fd))

#define	dprintf		if (Debug) printf

#define MAXUNAMES	20	/* maximum number of user names */

/*
 * Flags to logmsg().
 */

#define IGN_CONS	0x001	/* don't print on console */
#define SYNC_FILE	0x002	/* do fsync on file after printing */
#define ADDDATE		0x004	/* add a date to the message */
#define MARK		0x008	/* this message is a mark */

/*
 * This structure represents the files that will have log
 * copies printed.
 */

struct filed {
	struct	filed *f_next;		/* next in linked list */
	short	f_type;			/* entry type, see below */
	short	f_file;			/* file descriptor */
	time_t	f_time;			/* time this was last written */
	u_char	f_pmask[LOG_NFACILITIES+1];	/* priority mask */
	union {
		char	f_uname[MAXUNAMES][UT_NAMESIZE+1];
		struct {
			char	f_hname[MAXHOSTNAMELEN+1];
			struct sockaddr_in	f_addr;
		} f_forw;		/* forwarding address */
		char	f_fname[MAXPATHLEN];
	} f_un;
	char	f_prevline[MAXSVLINE];		/* last message logged */
	char	f_lasttime[16];			/* time of last occurrence */
	char	f_prevhost[MAXHOSTNAMELEN+1];	/* host from which recd. */
	int	f_prevpri;			/* pri of f_prevline */
	int	f_prevlen;			/* length of f_prevline */
	int	f_prevcount;			/* repetition cnt of prevline */
	int	f_repeatcount;			/* number of "repeated" msgs */
};

/*
 * Intervals at which we flush out "message repeated" messages,
 * in seconds after previous message is logged.  After each flush,
 * we move to the next interval until we reach the largest.
 */
int	repeatinterval[] = { 30, 120, 600 };	/* # of secs before flush */
#define	MAXREPEAT ((sizeof(repeatinterval) / sizeof(repeatinterval[0])) - 1)
#define	REPEATTIME(f)	((f)->f_time + repeatinterval[(f)->f_repeatcount])
#define	BACKOFF(f)	{ if (++(f)->f_repeatcount > MAXREPEAT) \
				 (f)->f_repeatcount = MAXREPEAT; \
			}

/* values for f_type */
#define F_UNUSED	0		/* unused entry */
#define F_FILE		1		/* regular file */
#define F_TTY		2		/* terminal */
#define F_CONSOLE	3		/* console terminal */
#define F_FORW		4		/* remote machine */
#define F_USERS		5		/* list of users */
#define F_WALL		6		/* everyone logged on */

char	*TypeNames[7] = {
	"UNUSED",	"FILE",		"TTY",		"CONSOLE",
	"FORW",		"USERS",	"WALL"
};

struct	filed *Files;
struct	filed consfile;

int	Debug;			/* debug flag */
char	LocalHostName[MAXHOSTNAMELEN+1];	/* our hostname */
char	*LocalDomain;		/* our local domain name */
int	InetInuse = 0;		/* non-zero if INET sockets are being used */
int	finet;			/* Internet datagram socket */
int	LogPort;		/* port number for INET connections */
int	Initialized = 0;	/* set when we have initialized ourselves */
int	MarkInterval = 20 * 60;	/* interval between marks in seconds */
int	MarkSeq = 0;		/* mark sequence number */

void	cfline __P((char *, struct filed *));
char   *cvthname __P((struct sockaddr_in *));
int	decode __P((const char *, CODE *));
void	die __P((int));
void	domark __P((int));
void	fprintlog __P((struct filed *, int, char *));
void	init __P((int));
void	logerror __P((char *));
void	logmsg __P((int, char *, char *, int));
void	printline __P((char *, char *));
void	printsys __P((char *));
void	reapchild __P((int));
char   *ttymsg __P((struct iovec *, int, char *, int));
void	usage __P((void));
void	wallmsg __P((struct filed *, struct iovec *));

int
main(argc, argv)
	int argc;
	char *argv[];
{
	int ch, funix, i, inetm, fklog, klogm, len;
	struct sockaddr_un sunx, fromunix;
	struct sockaddr_in sin, frominet;
	FILE *fp;
	char *p, line[MSG_BSIZE + 1];

	while ((ch = getopt(argc, argv, "df:m:p:")) != EOF)
		switch(ch) {
		case 'd':		/* debug */
			Debug++;
			break;
		case 'f':		/* configuration file */
			ConfFile = optarg;
			break;
		case 'm':		/* mark interval */
			MarkInterval = atoi(optarg) * 60;
			break;
		case 'p':		/* path */
			LogName = optarg;
			break;
		case '?':
		default:
			usage();
		}
	if ((argc -= optind) != 0)
		usage();

	if (!Debug)
		(void)daemon(0, 0);
	else
		setlinebuf(stdout);

	consfile.f_type = F_CONSOLE;
	(void)strcpy(consfile.f_un.f_fname, ctty);
	(void)gethostname(LocalHostName, sizeof(LocalHostName));
	if ((p = strchr(LocalHostName, '.')) != NULL) {
		*p++ = '\0';
		LocalDomain = p;
	} else
		LocalDomain = "";
	(void)signal(SIGTERM, die);
	(void)signal(SIGINT, Debug ? die : SIG_IGN);
	(void)signal(SIGQUIT, Debug ? die : SIG_IGN);
	(void)signal(SIGCHLD, reapchild);
	(void)signal(SIGALRM, domark);
	(void)alarm(TIMERINTVL);
	(void)unlink(LogName);

#ifndef SUN_LEN
#define SUN_LEN(unp) (strlen((unp)->sun_path) + 2)
#endif
	memset(&sunx, 0, sizeof(sunx));
	sunx.sun_family = AF_UNIX;
	(void)strncpy(sunx.sun_path, LogName, sizeof(sunx.sun_path));
	funix = socket(AF_UNIX, SOCK_DGRAM, 0);
	if (funix < 0 ||
	    bind(funix, (struct sockaddr *)&sunx, SUN_LEN(&sunx)) < 0 ||
	    chmod(LogName, 0666) < 0) {
		(void) sprintf(line, "cannot create %s", LogName);
		logerror(line);
		dprintf("cannot create %s (%d)\n", LogName, errno);
		die(0);
	}
	finet = socket(AF_INET, SOCK_DGRAM, 0);
	inetm = 0;
	if (finet >= 0) {
		struct servent *sp;

		sp = getservbyname("syslog", "udp");
		if (sp == NULL) {
			errno = 0;
			logerror("syslog/udp: unknown service");
			die(0);
		}
		memset(&sin, 0, sizeof(sin));
		sin.sin_family = AF_INET;
		sin.sin_port = LogPort = sp->s_port;
		if (bind(finet, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
			logerror("bind");
			if (!Debug)
				die(0);
		} else {
			inetm = FDMASK(finet);
			InetInuse = 1;
		}
	}
	if ((fklog = open(_PATH_KLOG, O_RDONLY, 0)) >= 0)
		klogm = FDMASK(fklog);
	else {
		dprintf("can't open %s (%d)\n", _PATH_KLOG, errno);
		klogm = 0;
	}

	/* tuck my process id away */
	fp = fopen(PidFile, "w");
	if (fp != NULL) {
		fprintf(fp, "%d\n", getpid());
		(void) fclose(fp);
	}

	dprintf("off & running....\n");

	init(0);
	(void)signal(SIGHUP, init);

	for (;;) {
		int nfds, readfds = FDMASK(funix) | inetm | klogm;

		dprintf("readfds = %#x\n", readfds);
		nfds = select(20, (fd_set *)&readfds, (fd_set *)NULL,
		    (fd_set *)NULL, (struct timeval *)NULL);
		if (nfds == 0)
			continue;
		if (nfds < 0) {
			if (errno != EINTR)
				logerror("select");
			continue;
		}
		dprintf("got a message (%d, %#x)\n", nfds, readfds);
		if (readfds & klogm) {
			i = read(fklog, line, sizeof(line) - 1);
			if (i > 0) {
				line[i] = '\0';
				printsys(line);
			} else if (i < 0 && errno != EINTR) {
				logerror("klog");
				fklog = -1;
				klogm = 0;
			}
		}
		if (readfds & FDMASK(funix)) {
			len = sizeof(fromunix);
			i = recvfrom(funix, line, MAXLINE, 0,
			    (struct sockaddr *)&fromunix, &len);
			if (i > 0) {
				line[i] = '\0';
				printline(LocalHostName, line);
			} else if (i < 0 && errno != EINTR)
				logerror("recvfrom unix");
		}
		if (readfds & inetm) {
			len = sizeof(frominet);
			i = recvfrom(finet, line, MAXLINE, 0,
			    (struct sockaddr *)&frominet, &len);
			if (i > 0) {
				line[i] = '\0';
				printline(cvthname(&frominet), line);
			} else if (i < 0 && errno != EINTR)
				logerror("recvfrom inet");
		} 
	}
}

void
usage()
{

	(void)fprintf(stderr,
	    "usage: syslogd [-f conffile] [-m markinterval] [-p logpath]\n");
	exit(1);
}

/*
 * Take a raw input line, decode the message, and print the message
 * on the appropriate log files.
 */
void
printline(hname, msg)
	char *hname;
	char *msg;
{
	int c, pri;
	char *p, *q, line[MAXLINE + 1];

	/* test for special codes */
	pri = DEFUPRI;
	p = msg;
	if (*p == '<') {
		pri = 0;
		while (isdigit(*++p))
			pri = 10 * pri + (*p - '0');
		if (*p == '>')
			++p;
	}
	if (pri &~ (LOG_FACMASK|LOG_PRIMASK))
		pri = DEFUPRI;

	/* don't allow users to log kernel messages */
	if (LOG_FAC(pri) == LOG_KERN)
		pri = LOG_MAKEPRI(LOG_USER, LOG_PRI(pri));

	q = line;

	while ((c = *p++ & 0177) != '\0' &&
	    q < &line[sizeof(line) - 1])
		if (iscntrl(c))
			if (c == '\n')
				*q++ = ' ';
			else if (c == '\t')
				*q++ = '\t';
			else {
				*q++ = '^';
				*q++ = c ^ 0100;
			}
		else
			*q++ = c;
	*q = '\0';

	logmsg(pri, line, hname, 0);
}

/*
 * Take a raw input line from /dev/klog, split and format similar to syslog().
 */
void
printsys(msg)
	char *msg;
{
	int c, pri, flags;
	char *lp, *p, *q, line[MAXLINE + 1];

	(void)strcpy(line, "vmunix: ");
	lp = line + strlen(line);
	for (p = msg; *p != '\0'; ) {
		flags = SYNC_FILE | ADDDATE;	/* fsync file after write */
		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);
	}
}

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, *from;
	int flags;
{
	struct filed *f;
	int fac, msglen, omask, prilev;
	char *timestamp;

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

	omask = sigblock(sigmask(SIGHUP)|sigmask(SIGALRM));

	/*
	 * 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, 0);

		if (f->f_file >= 0) {
			fprintlog(f, flags, msg);
			(void)close(f->f_file);
		}
		(void)sigsetmask(omask);
		return;
	}
	for (f = Files; f; f = f->f_next) {
		/* skip messages that are incorrect priority */
		if (f->f_pmask[fac] < prilev ||
		    f->f_pmask[fac] == INTERNAL_NOPRI)
			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, flags, (char *)NULL);
				BACKOFF(f);
			}
		} else {
			/* new line, save it */
			if (f->f_prevcount)
				fprintlog(f, 0, (char *)NULL);
			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;
				f->f_prevpri = pri;
				(void)strcpy(f->f_prevline, msg);
				fprintlog(f, flags, (char *)NULL);
			} else {
				f->f_prevline[0] = 0;
				f->f_prevlen = 0;
				fprintlog(f, flags, msg);
			}
		}