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Date:      Wed, 7 Oct 1998 11:57:03 +0200 (SAT)
From:      gram@cdsec.com
To:        FreeBSD-gnats-submit@FreeBSD.ORG
Subject:   bin/8183: Signal handlers in inetd.c are unsafe
Message-ID:  <199810070957.LAA04777@cdsec.com>

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>Number:         8183
>Category:       bin
>Synopsis:       Signal handlers in inetd.c are unsafe
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:
>Keywords:
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Oct  7 03:00:01 PDT 1998
>Last-Modified:
>Originator:     Graham Wheeler
>Organization:
Citadel Data Security
>Release:        FreeBSD 2.2.7
>Environment:
Not important
>Description:
The signal handlers in inetd.c make use of unsafe functions
>                such as calls to allocate and free heap memory. This can 
>                result in heap corruption, which is typically manifested
>                by inetd reporting the error message (from malloc or realloc):
>
>                   junk pointer: too low to make sense
>
>How-To-Repeat:
The problem will usually occur if a signal is caught while
>               in heap allocation function. The signal handler can also 
>               call these functions, which are not reentrant. As this is
>               timing related, replicating it reliably can be difficult, but
>               the problem is well known.	
>
>Fix:
The following inetd.c fixes the problem, by modifying the signal
>               handlers to write character flags to a pipe, and having the main
>               select() loop read these flags and call the original handlers.
>               The code also adds a new feature to inetd, allowing services
>               to be bound to specific addresses. This feature is enabled by
>               using the -X flag. A manual page is appended after the inetd.c
>               file.

----- inetd.c ---- cut here ------------------------------------
/*
 * Copyright (c) 1983, 1991, 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 const char copyright[] =
"@(#) Copyright (c) 1983, 1991, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)from: inetd.c	8.4 (Berkeley) 4/13/94";
#endif
static const char rcsid[] =
	"$Id: inetd.c,v 1.15.2.8 1998/07/18 11:10:26 jkh Exp $";
#endif /* not lint */

/*
 * Inetd - Internet super-server
 *
 * This program invokes all internet services as needed.  Connection-oriented
 * services are invoked each time a connection is made, by creating a process.
 * This process is passed the connection as file descriptor 0 and is expected
 * to do a getpeername to find out the source host and port.
 *
 * Datagram oriented services are invoked when a datagram
 * arrives; a process is created and passed a pending message
 * on file descriptor 0.  Datagram servers may either connect
 * to their peer, freeing up the original socket for inetd
 * to receive further messages on, or ``take over the socket'',
 * processing all arriving datagrams and, eventually, timing
 * out.	 The first type of server is said to be ``multi-threaded'';
 * the second type of server ``single-threaded''.
 *
 * Inetd uses a configuration file which is read at startup
 * and, possibly, at some later time in response to a hangup signal.
 * The configuration file is ``free format'' with fields given in the
 * order shown below.  Continuation lines for an entry must being with
 * a space or tab.  All fields must be present in each entry.
 *
 *	service name			must be in /etc/services or must
 *					name a tcpmux service
 *	socket type			stream/dgram/raw/rdm/seqpacket
 *	protocol			must be in /etc/protocols
 *	wait/nowait			single-threaded/multi-threaded
 *	user				user to run daemon as
 *	server program			full path name
 *	server program arguments	maximum of MAXARGS (20)
 *
 * TCP services without official port numbers are handled with the
 * RFC1078-based tcpmux internal service. Tcpmux listens on port 1 for
 * requests. When a connection is made from a foreign host, the service
 * requested is passed to tcpmux, which looks it up in the servtab list
 * and returns the proper entry for the service. Tcpmux returns a
 * negative reply if the service doesn't exist, otherwise the invoked
 * server is expected to return the positive reply if the service type in
 * inetd.conf file has the prefix "tcpmux/". If the service type has the
 * prefix "tcpmux/+", tcpmux will return the positive reply for the
 * process; this is for compatibility with older server code, and also
 * allows you to invoke programs that use stdin/stdout without putting any
 * special server code in them. Services that use tcpmux are "nowait"
 * because they do not have a well-known port and hence cannot listen
 * for new requests.
 *
 * For RPC services
 *	service name/version		must be in /etc/rpc
 *	socket type			stream/dgram/raw/rdm/seqpacket
 *	protocol			must be in /etc/protocols
 *	wait/nowait			single-threaded/multi-threaded
 *	user				user to run daemon as
 *	server program			full path name
 *	server program arguments	maximum of MAXARGS
 *
 * Comment lines are indicated by a `#' in column 1.
 */
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <rpc/rpc.h>
#include <rpc/pmap_clnt.h>

#include <errno.h>
#include <err.h>
#include <fcntl.h>
#include <grp.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <libutil.h>
#include <sysexits.h>

#ifdef LOGIN_CAP
#include <login_cap.h>

/* see init.c */
#define RESOURCE_RC "daemon"

#endif

#include "pathnames.h"

#ifndef	MAXCHILD
#define	MAXCHILD	-1		/* maximum number of this service
					   < 0 = no limit */
#endif

#ifndef	MAXCPM
#define	MAXCPM		-1		/* rate limit invocations from a
					   single remote address,
					   < 0 = no limit */
#endif

#define	TOOMANY		256		/* don't start more than TOOMANY */
#define	CNT_INTVL	60		/* servers in CNT_INTVL sec. */
#define	RETRYTIME	(60*10)		/* retry after bind or server fail */
#define MAX_MAXCHLD	32767		/* max allowable max children */

#define	SIGBLOCK	(sigmask(SIGCHLD)|sigmask(SIGHUP)|sigmask(SIGALRM))

int	debug = 0;
int	log = 0;
int	extended_format = 0;
int	nsock, maxsock;
fd_set	allsock;
int	options;
int	timingout;
int	toomany = TOOMANY;
int	maxchild = MAXCPM;
int	maxcpm = MAXCHILD;
struct	servent *sp;
struct	rpcent *rpc;
struct	in_addr bind_address;
int	signalpipe[2];

struct	servtab {
	char	*se_service;		/* name of service */
	int	se_socktype;		/* type of socket to use */
	char	*se_proto;		/* protocol used */
	int	se_maxchild;		/* max number of children */
	int	se_maxcpm;		/* max connects per IP per minute */
	int	se_numchild;		/* current number of children */
	pid_t	*se_pids;		/* array of child pids */
	char	*se_user;		/* user name to run as */
	char    *se_group;              /* group name to run as */
#ifdef  LOGIN_CAP
	char    *se_class;              /* login class name to run with */
#endif
	struct	biltin *se_bi;		/* if built-in, description */
	char	*se_server;		/* server program */
#define	MAXARGV 20
	char	*se_argv[MAXARGV+1];	/* program arguments */
	int	se_fd;			/* open descriptor */
	struct	sockaddr_in se_ctrladdr;/* bound address */
	u_char	se_type;		/* type: normal, mux, or mux+ */
	u_char	se_checked;		/* looked at during merge */
	u_char	se_accept;		/* i.e., wait/nowait mode */
	u_char	se_rpc;			/* ==1 if RPC service */
	int	se_rpc_prog;		/* RPC program number */
	u_int	se_rpc_lowvers;		/* RPC low version */
	u_int	se_rpc_highvers;	/* RPC high version */
	int	se_count;		/* number started since se_time */
	struct	timeval se_time;	/* start of se_count */
	struct	servtab *se_next;
} *servtab;

#define NORM_TYPE	0
#define MUX_TYPE	1
#define MUXPLUS_TYPE	2
#define TTCP_TYPE	3
#define ISMUX(sep)	(((sep)->se_type == MUX_TYPE) || \
			 ((sep)->se_type == MUXPLUS_TYPE))
#define ISMUXPLUS(sep)	((sep)->se_type == MUXPLUS_TYPE)
#define ISTTCP(sep)	((sep)->se_type == TTCP_TYPE)


void		chargen_dg __P((int, struct servtab *));
void		chargen_stream __P((int, struct servtab *));
void		close_sep __P((struct servtab *));
void		flag_signal __P((char));
void		flag_config __P((int));
void		config __P((void));
void		daytime_dg __P((int, struct servtab *));
void		daytime_stream __P((int, struct servtab *));
void		discard_dg __P((int, struct servtab *));
void		discard_stream __P((int, struct servtab *));
void		echo_dg __P((int, struct servtab *));
void		echo_stream __P((int, struct servtab *));
void		endconfig __P((void));
struct servtab *enter __P((struct servtab *));
void		freeconfig __P((struct servtab *));
struct servtab *getconfigent __P((void));
void		machtime_dg __P((int, struct servtab *));
void		machtime_stream __P((int, struct servtab *));
char	       *newstr __P((char *));
char	       *nextline __P((FILE *));
void		print_service __P((char *, struct servtab *));
void		addchild __P((struct servtab *, int));
void		flag_reapchild __P((int));
void		reapchild __P((void));
void		enable __P((struct servtab *));
void		disable __P((struct servtab *));
void		flag_retry __P((int));
void		retry __P((void));
int		setconfig __P((void));
void		setup __P((struct servtab *));
char	       *sskip __P((char **));
char	       *skip __P((char **));
struct servtab *tcpmux __P((int));
int		cpmip __P((struct servtab *, int));

void		unregisterrpc __P((register struct servtab *sep));

struct biltin {
	char	*bi_service;		/* internally provided service name */
	int	bi_socktype;		/* type of socket supported */
	short	bi_fork;		/* 1 if should fork before call */
	int	bi_maxchild;		/* max number of children (default) */
	void	(*bi_fn)();		/* function which performs it */
} biltins[] = {
	/* Echo received data */
	{ "echo",	SOCK_STREAM,	1, 0,	echo_stream },
	{ "echo",	SOCK_DGRAM,	0, 0,	echo_dg },

	/* Internet /dev/null */
	{ "discard",	SOCK_STREAM,	1, 0,	discard_stream },
	{ "discard",	SOCK_DGRAM,	0, 0,	discard_dg },

	/* Return 32 bit time since 1970 */
	{ "time",	SOCK_STREAM,	0, 0,	machtime_stream },
	{ "time",	SOCK_DGRAM,	0, 0,	machtime_dg },

	/* Return human-readable time */
	{ "daytime",	SOCK_STREAM,	0, 0,	daytime_stream },
	{ "daytime",	SOCK_DGRAM,	0, 0,	daytime_dg },

	/* Familiar character generator */
	{ "chargen",	SOCK_STREAM,	1, 0,	chargen_stream },
	{ "chargen",	SOCK_DGRAM,	0, 0,	chargen_dg },

	{ "tcpmux",	SOCK_STREAM,	1, 0,	(void (*)())tcpmux },

	{ NULL }
};

#define NUMINT	(sizeof(intab) / sizeof(struct inent))
char	*CONFIG = _PATH_INETDCONF;
char	*pid_file = _PATH_INETDPID;

#ifdef OLD_SETPROCTITLE
char	**Argv;
char 	*LastArg;
#endif

int
getvalue(arg, value, whine)
	char *arg, *whine;
	int  *value;
{
	int  tmp;
	char *p;

	tmp = strtol(arg, &p, 0);
	if (tmp < 1 || *p) {
		syslog(LOG_ERR, whine, arg);
		return 1;			/* failure */
	}
	*value = tmp;
	return 0;				/* success */
}

int
main(argc, argv, envp)
	int argc;
	char *argv[], *envp[];
{
	struct servtab *sep;
	struct passwd *pwd;
	struct group *grp;
	struct sigaction sa, sapipe;
	int tmpint, ch, dofork;
	pid_t pid;
	char buf[50];
	struct  sockaddr_in peer;
	int i;
#ifdef LOGIN_CAP
	login_cap_t *lc = NULL;
#endif


#ifdef OLD_SETPROCTITLE
	Argv = argv;
	if (envp == 0 || *envp == 0)
		envp = argv;
	while (*envp)
		envp++;
	LastArg = envp[-1] + strlen(envp[-1]);
#endif

	openlog("inetd", LOG_PID | LOG_NOWAIT, LOG_DAEMON);

	bind_address.s_addr = htonl(INADDR_ANY);
	while ((ch = getopt(argc, argv, "dlXR:a:c:C:p:")) != -1)
		switch(ch) {
		case 'd':
			debug = 1;
			options |= SO_DEBUG;
			break;
		case 'l':
			log = 1;
			break;
		case 'X':
			extended_format = 1;
			break;
		case 'R':
			getvalue(optarg, &toomany,
				"-R %s: bad value for service invocation rate");
			break;
		case 'c':
			getvalue(optarg, &maxchild,
				"-c %s: bad value for maximum children");
			break;
		case 'C':
			getvalue(optarg, &maxcpm,
				"-C %s: bad value for maximum children/minute");
			break;
		case 'a':
			if (!inet_aton(optarg, &bind_address)) {
				syslog(LOG_ERR,
			         "-a %s: invalid IP address", optarg);
				exit(EX_USAGE);
			}
			break;
		case 'p':
			pid_file = optarg;
			break;
		case '?':
		default:
			syslog(LOG_ERR,
				"usage: inetd [-dl] [-a address] [-R rate]"
				" [-c maximum] [-C rate]"
				" [-p pidfile] [conf-file]");
			exit(EX_USAGE);
		}
	argc -= optind;
	argv += optind;

	if (argc > 0)
		CONFIG = argv[0];
	if (debug == 0) {
		FILE *fp;
		if (daemon(0, 0) < 0) {
			syslog(LOG_WARNING, "daemon(0,0) failed: %m");
		}
		/*
		 * In case somebody has started inetd manually, we need to
		 * clear the logname, so that old servers run as root do not
		 * get the user's logname..
		 */
		if (setlogin("") < 0) {
			syslog(LOG_WARNING, "cannot clear logname: %m");
			/* no big deal if it fails.. */
		}
		pid = getpid();
		fp = fopen(pid_file, "w");
		if (fp) {
			fprintf(fp, "%ld\n", (long)pid);
			fclose(fp);
		} else {
			syslog(LOG_WARNING, "%s: %m", pid_file);
		}
	}
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	sigaddset(&sa.sa_mask, SIGALRM);
	sigaddset(&sa.sa_mask, SIGCHLD);
	sigaddset(&sa.sa_mask, SIGHUP);
	sa.sa_handler = flag_retry;
	sigaction(SIGALRM, &sa, (struct sigaction *)0);
	config();
	sa.sa_handler = flag_config;
	sigaction(SIGHUP, &sa, (struct sigaction *)0);
	sa.sa_handler = flag_reapchild;
	sigaction(SIGCHLD, &sa, (struct sigaction *)0);
	sa.sa_handler = SIG_IGN;
	sigaction(SIGPIPE, &sa, &sapipe);

	{
		/* space for daemons to overwrite environment for ps */
#define	DUMMYSIZE	100
		char dummy[DUMMYSIZE];

		(void)memset(dummy, 'x', DUMMYSIZE - 1);
		dummy[DUMMYSIZE - 1] = '\0';
		(void)setenv("inetd_dummy", dummy, 1);
	}

	if (pipe(signalpipe) != 0)
	{
	    syslog(LOG_ERR, "pipe: %%m");
	    exit(EX_OSERR);
	}
	FD_SET(signalpipe[0], &allsock);
	if (signalpipe[0]>maxsock) maxsock = signalpipe[0];

	for (;;) {
	    int n, ctrl;
	    fd_set readable;

	    if (nsock == 0) {
		(void) sigblock(SIGBLOCK);
		while (nsock == 0)
		    sigpause(0L);
		(void) sigsetmask(0L);
	    }
	    readable = allsock;
	    if ((n = select(maxsock + 1, &readable, (fd_set *)0,
		(fd_set *)0, (struct timeval *)0)) <= 0) {
		    if (n < 0 && errno != EINTR) {
			syslog(LOG_WARNING, "select: %m");
			sleep(1);
		    }
		    continue;
	    }
	    /* handle any queued signal flags */
	    if (FD_ISSET(signalpipe[0], &readable))
	    {
		int n;
		if (ioctl(signalpipe[0], FIONREAD, &n) == 0)
		{
		    while (--n >= 0)
		    {
			char c;
			if (read(signalpipe[0], &c, 1) == 1)
			{
			    if (debug) warnx("Handling signal flag %c", c);
		    	    switch(c)
		    	    {
		    	    case 'A': /* sigalrm */
				retry(); break;
		    	    case 'C': /* sigchld */
				reapchild(); break;
		    	    case 'H': /* sighup */
				config(); break;
		    	    }
			}
			else
			{
		    	    syslog(LOG_ERR, "read: %m");
		    	    exit(EX_OSERR);
			}
		    }
		}
		else
		{
		    syslog(LOG_ERR, "ioctl: %m");
		    exit(EX_OSERR);
		}
	    }
	    for (sep = servtab; n && sep; sep = sep->se_next)
	        if (sep->se_fd != -1 && FD_ISSET(sep->se_fd, &readable)) {
		    n--;
		    if (debug)
			    warnx("someone wants %s", sep->se_service);
		    if (sep->se_accept && sep->se_socktype == SOCK_STREAM) {
			    ctrl = accept(sep->se_fd, (struct sockaddr *)0,
				(int *)0);
			    if (debug)
				    warnx("accept, ctrl %d", ctrl);
			    if (ctrl < 0) {
				    if (errno != EINTR)
					    syslog(LOG_WARNING,
						"accept (for %s): %m",
						sep->se_service);
				    continue;
			    }
			    if (cpmip(sep, ctrl) < 0) {
				close(ctrl);
				continue;
			    }
			    if (log) {
				i = sizeof peer;
				if (getpeername(ctrl, (struct sockaddr *)
						&peer, &i)) {
					syslog(LOG_WARNING,
						"getpeername(for %s): %m",
						sep->se_service);
					close(ctrl);
					continue;
				}
				syslog(LOG_INFO,"%s from %s",
					sep->se_service,
					inet_ntoa(peer.sin_addr));
			    }
		    } else
			    ctrl = sep->se_fd;
		    (void) sigblock(SIGBLOCK);
		    pid = 0;
		    dofork = (sep->se_bi == 0 || sep->se_bi->bi_fork);
		    if (dofork) {
			    if (sep->se_count++ == 0)
				(void)gettimeofday(&sep->se_time,
				    (struct timezone *)0);
			    else if (sep->se_count >= toomany) {
				struct timeval now;

				(void)gettimeofday(&now, (struct timezone *)0);
				if (now.tv_sec - sep->se_time.tv_sec >
				    CNT_INTVL) {
					sep->se_time = now;
					sep->se_count = 1;
				} else {
					syslog(LOG_ERR,
			"%s/%s server failing (looping), service terminated",
					    sep->se_service, sep->se_proto);
					close_sep(sep);
					sigsetmask(0L);
					if (!timingout) {
						timingout = 1;
						alarm(RETRYTIME);
					}
					continue;
				}
			    }
			    pid = fork();
		    }
		    if (pid < 0) {
			    syslog(LOG_ERR, "fork: %m");
			    if (sep->se_accept &&
				sep->se_socktype == SOCK_STREAM)
				    close(ctrl);
			    sigsetmask(0L);
			    sleep(1);
			    continue;
		    }
		    if (pid)
			addchild(sep, pid);
		    sigsetmask(0L);
		    if (pid == 0) {
			    if (dofork) {
				if (debug)
					warnx("+ closing from %d", maxsock);
				for (tmpint = maxsock; tmpint > 2; tmpint--)
					if (tmpint != ctrl)
						(void) close(tmpint);
			    }
			    /*
			     * Call tcpmux to find the real service to exec.
			     */
			    if (sep->se_bi &&
				sep->se_bi->bi_fn == (void (*)()) tcpmux) {
				    sep = tcpmux(ctrl);
				    if (sep == NULL) {
					    close(ctrl);
					    _exit(0);
				    }
			    }
			    if (sep->se_bi) {
				(*sep->se_bi->bi_fn)(ctrl, sep);
				/* NOTREACHED */
			    } else {
				if (debug)
					warnx("%d execl %s",
						getpid(), sep->se_server);
				dup2(ctrl, 0);
				close(ctrl);
				dup2(0, 1);
				dup2(0, 2);
				if ((pwd = getpwnam(sep->se_user)) == NULL) {
					syslog(LOG_ERR,
					    "%s/%s: %s: No such user",
						sep->se_service, sep->se_proto,
						sep->se_user);
					if (sep->se_socktype != SOCK_STREAM)
						recv(0, buf, sizeof (buf), 0);
					_exit(EX_NOUSER);
				}
				grp = NULL;
				if (   sep->se_group != NULL
				    && (grp = getgrnam(sep->se_group)) == NULL
				   ) {
					syslog(LOG_ERR,
					    "%s/%s: %s: No such group",
						sep->se_service, sep->se_proto,
						sep->se_group);
					if (sep->se_socktype != SOCK_STREAM)
						recv(0, buf, sizeof (buf), 0);
					_exit(EX_NOUSER);
				}
				if (grp != NULL)
					pwd->pw_gid = grp->gr_gid;
#ifdef LOGIN_CAP
				if ((lc = login_getclass(sep->se_class)) == NULL) {
					/* error syslogged by getclass */
					syslog(LOG_ERR,
					    "%s/%s: %s: login class error",
						sep->se_service, sep->se_proto);
					if (sep->se_socktype != SOCK_STREAM)
						recv(0, buf, sizeof (buf), 0);
					_exit(EX_NOUSER);
				}
#endif
				if (setsid() < 0) {
					syslog(LOG_ERR,
						"%s: can't setsid(): %m",
						 sep->se_service);
					/* _exit(EX_OSERR); not fatal yet */
				}
#ifdef LOGIN_CAP
				if (setusercontext(lc, pwd, pwd->pw_uid,
				    LOGIN_SETALL) != 0) {
					syslog(LOG_ERR,
					 "%s: can't setusercontext(..%s..): %m",
					 sep->se_service, sep->se_user);
					_exit(EX_OSERR);
				}
#else
				if (pwd->pw_uid) {
					if (setlogin(sep->se_user) < 0) {
						syslog(LOG_ERR,
						 "%s: can't setlogin(%s): %m",
						 sep->se_service, sep->se_user);
						/* _exit(EX_OSERR); not yet */
					}
					if (setgid(pwd->pw_gid) < 0) {
						syslog(LOG_ERR,
						  "%s: can't set gid %d: %m",
						  sep->se_service, pwd->pw_gid);
						_exit(EX_OSERR);
					}
					(void) initgroups(pwd->pw_name,
							pwd->pw_gid);
					if (setuid(pwd->pw_uid) < 0) {
						syslog(LOG_ERR,
						  "%s: can't set uid %d: %m",
						  sep->se_service, pwd->pw_uid);
						_exit(EX_OSERR);
					}
				}
#endif
				sigaction(SIGPIPE, &sapipe,
				    (struct sigaction *)0);
				execv(sep->se_server, sep->se_argv);
				if (sep->se_socktype != SOCK_STREAM)
					recv(0, buf, sizeof (buf), 0);
				syslog(LOG_ERR,
				    "cannot execute %s: %m", sep->se_server);
				_exit(EX_OSERR);
			    }
		    }
		    if (sep->se_accept && sep->se_socktype == SOCK_STREAM)
			    close(ctrl);
		}
	}
}

/*
 * Add a signal flag to the signal flag queue for later handling
 */

void flag_signal(c)
    char c;
{
    if (write(signalpipe[1], &c, 1) != 1)
    {
	syslog(LOG_ERR, "write: %m");
	exit(EX_OSERR);
    }
}

/*
 * Record a new child pid for this service. If we've reached the
 * limit on children, then stop accepting incoming requests.
 */

void
addchild(struct servtab *sep, pid_t pid)
{
#ifdef SANITY_CHECK
	if (sep->se_numchild >= sep->se_maxchild) {
		syslog(LOG_ERR, "%s: %d >= %d",
		    __FUNCTION__, sep->se_numchild, sep->se_maxchild);
		exit(EX_SOFTWARE);
	}
#endif
	if (sep->se_maxchild == 0)
		return;
	sep->se_pids[sep->se_numchild++] = pid;
	if (sep->se_numchild == sep->se_maxchild)
		disable(sep);
}

/*
 * Some child process has exited. See if it's on somebody's list.
 */

void
flag_reapchild(signo)
	int signo;
{
    flag_signal('C');
}

void
reapchild()
{
	int k, status;
	pid_t pid;
	struct servtab *sep;

	for (;;) {
		pid = wait3(&status, WNOHANG, (struct rusage *)0);
		if (pid <= 0)
			break;
		if (debug)
			warnx("%d reaped, status %#x", pid, status);
		for (sep = servtab; sep; sep = sep->se_next) {
			for (k = 0; k < sep->se_numchild; k++)
				if (sep->se_pids[k] == pid)
					break;
			if (k == sep->se_numchild)
				continue;
			if (sep->se_numchild == sep->se_maxchild)
				enable(sep);
			sep->se_pids[k] = sep->se_pids[--sep->se_numchild];
			if (status)
				syslog(LOG_WARNING,
				    "%s[%d]: exit status 0x%x",
				    sep->se_server, pid, status);
			break;
		}
	}
}

void
flag_config(signo)
	int signo;
{
    flag_signal('H');
}

void config()
{
	struct servtab *sep, *new, **sepp;
	long omask;

	if (!setconfig()) {
		syslog(LOG_ERR, "%s: %m", CONFIG);
		return;
	}
	for (sep = servtab; sep; sep = sep->se_next)
		sep->se_checked = 0;
	while ((new = getconfigent())) {
		if (getpwnam(new->se_user) == NULL) {
			syslog(LOG_ERR,
				"%s/%s: No such user '%s', service ignored",
				new->se_service, new->se_proto, new->se_user);
			continue;
		}
		if (new->se_group && getgrnam(new->se_group) == NULL) {
			syslog(LOG_ERR,
				"%s/%s: No such group '%s', service ignored",
				new->se_service, new->se_proto, new->se_group);
			continue;
		}
#ifdef LOGIN_CAP
		if (login_getclass(new->se_class) == NULL) {
			/* error syslogged by getclass */
			syslog(LOG_ERR,
				"%s/%s: login class error, service ignored",
				new->se_service, new->se_proto);
			continue;
		}
#endif
		for (sep = servtab; sep; sep = sep->se_next)
			if (strcmp(sep->se_service, new->se_service) == 0 &&
			    strcmp(sep->se_proto, new->se_proto) == 0 &&
			    (!extended_format ||
			      sep->se_ctrladdr.sin_addr.s_addr ==
					new->se_ctrladdr.sin_addr.s_addr))
				break;
		if (sep != 0) {
			int i;

#define SWAP(a, b) { typeof(a) c = a; a = b; b = c; }
			omask = sigblock(SIGBLOCK);
			/* copy over outstanding child pids */
			if (sep->se_maxchild && new->se_maxchild) {
				new->se_numchild = sep->se_numchild;
				if (new->se_numchild > new->se_maxchild)
					new->se_numchild = new->se_maxchild;
				memcpy(new->se_pids, sep->se_pids,
				    new->se_numchild * sizeof(*new->se_pids));
			}
			SWAP(sep->se_pids, new->se_pids);
			sep->se_maxchild = new->se_maxchild;
			sep->se_numchild = new->se_numchild;
			sep->se_maxcpm = new->se_maxcpm;
			/* might need to turn on or off service now */
			if (sep->se_fd >= 0) {
			      if (sep->se_maxchild
				  && sep->se_numchild == sep->se_maxchild) {
				      if (FD_ISSET(sep->se_fd, &allsock))
					  disable(sep);
			      } else {
				      if (!FD_ISSET(sep->se_fd, &allsock))
					  enable(sep);
			      }
			}
			sep->se_accept = new->se_accept;
			SWAP(sep->se_user, new->se_user);
			SWAP(sep->se_group, new->se_group);
#ifdef LOGIN_CAP
			SWAP(sep->se_class, new->se_class);
#endif
			SWAP(sep->se_server, new->se_server);
			for (i = 0; i < MAXARGV; i++)
				SWAP(sep->se_argv[i], new->se_argv[i]);
			sigsetmask(omask);
			freeconfig(new);
			if (debug)
				print_service("REDO", sep);
		} else {
			sep = enter(new);
			if (debug)
				print_service("ADD ", sep);
		}
		sep->se_checked = 1;
		if (ISMUX(sep)) {
			sep->se_fd = -1;
			continue;
		}
		if (!sep->se_rpc) {
			sp = getservbyname(sep->se_service, sep->se_proto);
			if (sp == 0) {
				syslog(LOG_ERR, "%s/%s: unknown service",
			    	sep->se_service, sep->se_proto);
				sep->se_checked = 0;
				continue;
			}
			if (sp->s_port != sep->se_ctrladdr.sin_port) {
				sep->se_ctrladdr.sin_family = AF_INET;
				if (!extended_format)
				    sep->se_ctrladdr.sin_addr = bind_address;
				sep->se_ctrladdr.sin_port = sp->s_port;
				if (sep->se_fd >= 0)
					close_sep(sep);
			}
		} else {
			rpc = getrpcbyname(sep->se_service);
			if (rpc == 0) {
				syslog(LOG_ERR, "%s/%s unknown RPC service.",
					sep->se_service, sep->se_proto);
				if (sep->se_fd != -1)
					(void) close(sep->se_fd);
				sep->se_fd = -1;
					continue;
			}
			if (rpc->r_number != sep->se_rpc_prog) {
				if (sep->se_rpc_prog)
					unregisterrpc(sep);
				sep->se_rpc_prog = rpc->r_number;
				if (sep->se_fd != -1)
					(void) close(sep->se_fd);
				sep->se_fd = -1;
			}
		}
		if (sep->se_fd == -1)
			setup(sep);
	}
	endconfig();
	/*
	 * Purge anything not looked at above.
	 */
	omask = sigblock(SIGBLOCK);
	sepp = &servtab;
	while ((sep = *sepp)) {
		if (sep->se_checked) {
			sepp = &sep->se_next;
			continue;
		}
		*sepp = sep->se_next;
		if (sep->se_fd >= 0)
			close_sep(sep);
		if (debug)
			print_service("FREE", sep);
		if (sep->se_rpc && sep->se_rpc_prog > 0)
			unregisterrpc(sep);
		freeconfig(sep);
		free((char *)sep);
	}
	(void) sigsetmask(omask);
}

void
unregisterrpc(sep)
	struct servtab *sep;
{
        int i;
        struct servtab *sepp;
	long omask;

	omask = sigblock(SIGBLOCK);
        for (sepp = servtab; sepp; sepp = sepp->se_next) {
                if (sepp == sep)
                        continue;
		if (sep->se_checked == 0 ||
                    !sepp->se_rpc ||
                    sep->se_rpc_prog != sepp->se_rpc_prog)
			continue;
                return;
        }
        if (debug)
                print_service("UNREG", sep);
        for (i = sep->se_rpc_lowvers; i <= sep->se_rpc_highvers; i++)
                pmap_unset(sep->se_rpc_prog, i);
        if (sep->se_fd != -1)
                (void) close(sep->se_fd);
        sep->se_fd = -1;
	(void) sigsetmask(omask);
}

void
flag_retry(signo)
	int signo;
{
    flag_signal('A');
}

void
retry()
{
	struct servtab *sep;

	timingout = 0;
	for (sep = servtab; sep; sep = sep->se_next)
		if (sep->se_fd == -1 && !ISMUX(sep))
			setup(sep);
}

void
setup(sep)
	struct servtab *sep;
{
	int on = 1;

	if ((sep->se_fd = socket(AF_INET, sep->se_socktype, 0)) < 0) {
		if (debug)
			warn("socket failed on %s/%s",
				sep->se_service, sep->se_proto);
		syslog(LOG_ERR, "%s/%s: socket: %m",
		    sep->se_service, sep->se_proto);
		return;
	}
#define	turnon(fd, opt) \
setsockopt(fd, SOL_SOCKET, opt, (char *)&on, sizeof (on))
	if (strcmp(sep->se_proto, "tcp") == 0 && (options & SO_DEBUG) &&
	    turnon(sep->se_fd, SO_DEBUG) < 0)
		syslog(LOG_ERR, "setsockopt (SO_DEBUG): %m");
	if (turnon(sep->se_fd, SO_REUSEADDR) < 0)
		syslog(LOG_ERR, "setsockopt (SO_REUSEADDR): %m");
#ifdef SO_PRIVSTATE
	if (turnon(sep->se_fd, SO_PRIVSTATE) < 0)
		syslog(LOG_ERR, "setsockopt (SO_PRIVSTATE): %m");
#endif
#undef turnon
	if (sep->se_type == TTCP_TYPE)
		if (setsockopt(sep->se_fd, IPPROTO_TCP, TCP_NOPUSH,
		    (char *)&on, sizeof (on)) < 0)
			syslog(LOG_ERR, "setsockopt (TCP_NOPUSH): %m");
	if (bind(sep->se_fd, (struct sockaddr *)&sep->se_ctrladdr,
	    sizeof (sep->se_ctrladdr)) < 0) {
		if (debug)
			warn("bind failed on %s/%s",
				sep->se_service, sep->se_proto);
		syslog(LOG_ERR, "%s/%s: bind: %m",
		    sep->se_service, sep->se_proto);
		(void) close(sep->se_fd);
		sep->se_fd = -1;
		if (!timingout) {
			timingout = 1;
			alarm(RETRYTIME);
		}
		return;
	}
        if (sep->se_rpc) {
                int i, len = sizeof(struct sockaddr);

                if (getsockname(sep->se_fd,
				(struct sockaddr*)&sep->se_ctrladdr, &len) < 0){
                        syslog(LOG_ERR, "%s/%s: getsockname: %m",
                               sep->se_service, sep->se_proto);
                        (void) close(sep->se_fd);
                        sep->se_fd = -1;
                        return;
                }
                if (debug)
                        print_service("REG ", sep);
                for (i = sep->se_rpc_lowvers; i <= sep->se_rpc_highvers; i++) {
                        pmap_unset(sep->se_rpc_prog, i);
                        pmap_set(sep->se_rpc_prog, i,
                                 (sep->se_socktype == SOCK_DGRAM)
                                 ? IPPROTO_UDP : IPPROTO_TCP,
                                 ntohs(sep->se_ctrladdr.sin_port));
                }

        }
	if (sep->se_socktype == SOCK_STREAM)
		listen(sep->se_fd, 64);
	enable(sep);
	if (debug) {
		warnx("registered %s on %d",
			sep->se_server, sep->se_fd);
	}
}

/*
 * Finish with a service and its socket.
 */
void
close_sep(sep)
	struct servtab *sep;
{
	if (sep->se_fd >= 0) {
		if (FD_ISSET(sep->se_fd, &allsock))
			disable(sep);
		(void) close(sep->se_fd);
		sep->se_fd = -1;
	}
	sep->se_count = 0;
	sep->se_numchild = 0;	/* forget about any existing children */
}

struct servtab *
enter(cp)
	struct servtab *cp;
{
	struct servtab *sep;
	long omask;

	sep = (struct servtab *)malloc(sizeof (*sep));
	if (sep == (struct servtab *)0) {
		syslog(LOG_ERR, "Out of memory.");
		exit(EX_OSERR);
	}
	*sep = *cp;
	sep->se_fd = -1;
	omask = sigblock(SIGBLOCK);
	sep->se_next = servtab;
	servtab = sep;
	sigsetmask(omask);
	return (sep);
}

void
enable(struct servtab *sep)
{
	if (debug)
		warnx(
		    "enabling %s, fd %d", sep->se_service, sep->se_fd);
#ifdef SANITY_CHECK
	if (sep->se_fd < 0) {
		syslog(LOG_ERR,
		    "%s: %s: bad fd", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
	if (ISMUX(sep)) {
		syslog(LOG_ERR,
		    "%s: %s: is mux", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
	if (FD_ISSET(sep->se_fd, &allsock)) {
		syslog(LOG_ERR,
		    "%s: %s: not off", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
#endif
	FD_SET(sep->se_fd, &allsock);
	nsock++;
	if (sep->se_fd > maxsock)
		maxsock = sep->se_fd;
}

void
disable(struct servtab *sep)
{
	if (debug)
		warnx(
		    "disabling %s, fd %d", sep->se_service, sep->se_fd);
#ifdef SANITY_CHECK
	if (sep->se_fd < 0) {
		syslog(LOG_ERR,
		    "%s: %s: bad fd", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
	if (ISMUX(sep)) {
		syslog(LOG_ERR,
		    "%s: %s: is mux", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
	if (!FD_ISSET(sep->se_fd, &allsock)) {
		syslog(LOG_ERR,
		    "%s: %s: not on", __FUNCTION__, sep->se_service);
		exit(EX_SOFTWARE);
	}
	if (nsock == 0) {
		syslog(LOG_ERR, "%s: nsock=0", __FUNCTION__);
		exit(EX_SOFTWARE);
	}
#endif
	FD_CLR(sep->se_fd, &allsock);
	nsock--;
	if (sep->se_fd == maxsock)
		maxsock--;
}

FILE	*fconfig = NULL;
struct	servtab serv;
char	line[LINE_MAX];

int
setconfig()
{

	if (fconfig != NULL) {
		fseek(fconfig, 0L, SEEK_SET);
		return (1);
	}
	fconfig = fopen(CONFIG, "r");
	return (fconfig != NULL);
}

void
endconfig()
{
	if (fconfig) {
		(void) fclose(fconfig);
		fconfig = NULL;
	}
}

struct servtab *
getconfigent()
{
	struct servtab *sep = &serv;
	int argc;
	char *cp, *arg, *s;
	char *versp;
	static char TCPMUX_TOKEN[] = "tcpmux/";
#define MUX_LEN		(sizeof(TCPMUX_TOKEN)-1)

more:
	while ((cp = nextline(fconfig)) && (*cp == '#' || *cp == '\0'))
		;
	if (cp == NULL)
		return ((struct servtab *)0);
	/*
	 * clear the static buffer, since some fields (se_ctrladdr,
	 * for example) don't get initialized here.
	 */
	memset((caddr_t)sep, 0, sizeof *sep);
	arg = skip(&cp);
	if (cp == NULL) {
		/* got an empty line containing just blanks/tabs. */
		goto more;
	}
	if (extended_format)
	{
	    if (strcmp(arg, "any") == 0)
                sep->se_ctrladdr.sin_addr.s_addr = INADDR_ANY;
	    else
                sep->se_ctrladdr.sin_addr.s_addr = inet_addr(arg);
	    arg = sskip(&cp);
	}
	if (strncmp(arg, TCPMUX_TOKEN, MUX_LEN) == 0) {
		char *c = arg + MUX_LEN;
		if (*c == '+') {
			sep->se_type = MUXPLUS_TYPE;
			c++;
		} else
			sep->se_type = MUX_TYPE;
		sep->se_service = newstr(c);
	} else {
		sep->se_service = newstr(arg);
		sep->se_type = NORM_TYPE;
	}
	arg = sskip(&cp);
	if (strcmp(arg, "stream") == 0)
		sep->se_socktype = SOCK_STREAM;
	else if (strcmp(arg, "dgram") == 0)
		sep->se_socktype = SOCK_DGRAM;
	else if (strcmp(arg, "rdm") == 0)
		sep->se_socktype = SOCK_RDM;
	else if (strcmp(arg, "seqpacket") == 0)
		sep->se_socktype = SOCK_SEQPACKET;
	else if (strcmp(arg, "raw") == 0)
		sep->se_socktype = SOCK_RAW;
	else
		sep->se_socktype = -1;

	arg = sskip(&cp);
	if (strcmp(arg, "tcp/ttcp") == 0) {
		sep->se_type = TTCP_TYPE;
		sep->se_proto = newstr("tcp");
	} else {
		sep->se_proto = newstr(arg);
	}
        if (strncmp(sep->se_proto, "rpc/", 4) == 0) {
                memmove(sep->se_proto, sep->se_proto + 4,
                    strlen(sep->se_proto) + 1 - 4);
                sep->se_rpc = 1;
                sep->se_rpc_prog = sep->se_rpc_lowvers =
			sep->se_rpc_lowvers = 0;
                sep->se_ctrladdr.sin_family = AF_INET;
                sep->se_ctrladdr.sin_port = 0;
                if (!extended_format)
		    sep->se_ctrladdr.sin_addr = bind_address;
                if ((versp = rindex(sep->se_service, '/'))) {
                        *versp++ = '\0';
                        switch (sscanf(versp, "%d-%d",
                                       &sep->se_rpc_lowvers,
                                       &sep->se_rpc_highvers)) {
                        case 2:
                                break;
                        case 1:
                                sep->se_rpc_highvers =
                                        sep->se_rpc_lowvers;
                                break;
                        default:
                                syslog(LOG_ERR,
					"bad RPC version specifier; %s\n",
					sep->se_service);
                                freeconfig(sep);
                                goto more;
                        }
                }
                else {
                        sep->se_rpc_lowvers =
                                sep->se_rpc_highvers = 1;
                }
        }
	arg = sskip(&cp);
	if (!strncmp(arg, "wait", 4))
		sep->se_accept = 0;
	else if (!strncmp(arg, "nowait", 6))
		sep->se_accept = 1;
	else {
		syslog(LOG_ERR,
			"%s: bad wait/nowait for service %s",
			CONFIG, sep->se_service);
		goto more;
	}
	sep->se_maxchild = maxchild;
	sep->se_maxcpm = maxcpm;
	if ((s = strchr(arg, '/')) != NULL) {
		char *eptr;
		u_long val;

		val = strtoul(s + 1, &eptr, 10);
		if (eptr == s + 1 || val > MAX_MAXCHLD) {
			syslog(LOG_ERR,
				"%s: bad max-child for service %s",
				CONFIG, sep->se_service);
			goto more;
		}
		sep->se_maxchild = val;
		if (*eptr == '/')
			sep->se_maxcpm = strtol(eptr + 1, &eptr, 10);
		/*
		 * explicitly do not check for \0 for future expansion /
		 * backwards compatibility
		 */
	}
	if (ISMUX(sep)) {
		/*
		 * Silently enforce "nowait" mode for TCPMUX services
		 * since they don't have an assigned port to listen on.
		 */
		sep->se_accept = 1;
		if (strcmp(sep->se_proto, "tcp")) {
			syslog(LOG_ERR,
				"%s: bad protocol for tcpmux service %s",
				CONFIG, sep->se_service);
			goto more;
		}
		if (sep->se_socktype != SOCK_STREAM) {
			syslog(LOG_ERR,
				"%s: bad socket type for tcpmux service %s",
				CONFIG, sep->se_service);
			goto more;
		}
	}
	sep->se_user = newstr(sskip(&cp));
#ifdef LOGIN_CAP
	if ((s = strrchr(sep->se_user, '/')) != NULL) {
		*s = '\0';
		sep->se_class = newstr(s + 1);
	} else
		sep->se_class = newstr(RESOURCE_RC);
#endif
	if ((s = strrchr(sep->se_user, ':')) != NULL) {
		*s = '\0';
		sep->se_group = newstr(s + 1);
	} else
		sep->se_group = NULL;
	sep->se_server = newstr(sskip(&cp));
	if (strcmp(sep->se_server, "internal") == 0) {
		struct biltin *bi;

		for (bi = biltins; bi->bi_service; bi++)
			if (bi->bi_socktype == sep->se_socktype &&
			    strcmp(bi->bi_service, sep->se_service) == 0)
				break;
		if (bi->bi_service == 0) {
			syslog(LOG_ERR, "internal service %s unknown",
				sep->se_service);
			goto more;
		}
		sep->se_accept = 1;	/* force accept mode for built-ins */
		sep->se_bi = bi;
	} else
		sep->se_bi = NULL;
	if (sep->se_maxchild < 0)	/* apply default max-children */
		if (sep->se_bi)
			sep->se_maxchild = sep->se_bi->bi_maxchild;
		else
			sep->se_maxchild = sep->se_accept ? 0 : 1;
	if (sep->se_maxchild) {
		sep->se_pids = malloc(sep->se_maxchild * sizeof(*sep->se_pids));
		if (sep->se_pids == NULL) {
			syslog(LOG_ERR, "Out of memory.");
			exit(EX_OSERR);
		}
	}
	argc = 0;
	for (arg = skip(&cp); cp; arg = skip(&cp))
		if (argc < MAXARGV) {
			sep->se_argv[argc++] = newstr(arg);
		} else {
			syslog(LOG_ERR,
				"%s: too many arguments for service %s",
				CONFIG, sep->se_service);
			goto more;
		}
	while (argc <= MAXARGV)
		sep->se_argv[argc++] = NULL;
	return (sep);
}

void
freeconfig(cp)
	struct servtab *cp;
{
	int i;

	if (cp->se_service)
		free(cp->se_service);
	if (cp->se_proto)
		free(cp->se_proto);
	if (cp->se_user)
		free(cp->se_user);
	if (cp->se_group)
		free(cp->se_group);
#ifdef LOGIN_CAP
	if (cp->se_class)
		free(cp->se_class);
#endif
	if (cp->se_server)
		free(cp->se_server);
	if (cp->se_pids)
		free(cp->se_pids);
	for (i = 0; i < MAXARGV; i++)
		if (cp->se_argv[i])
			free(cp->se_argv[i]);
}


/*
 * Safe skip - if skip returns null, log a syntax error in the
 * configuration file and exit.
 */
char *
sskip(cpp)
	char **cpp;
{
	char *cp;

	cp = skip(cpp);
	if (cp == NULL) {
		syslog(LOG_ERR, "%s: syntax error", CONFIG);
		exit(EX_DATAERR);
	}
	return (cp);
}

char *
skip(cpp)
	char **cpp;
{
	char *cp = *cpp;
	char *start;
	char quote = '\0';

again:
	while (*cp == ' ' || *cp == '\t')
		cp++;
	if (*cp == '\0') {
		int c;

		c = getc(fconfig);
		(void) ungetc(c, fconfig);
		if (c == ' ' || c == '\t')
			if ((cp = nextline(fconfig)))
				goto again;
		*cpp = (char *)0;
		return ((char *)0);
	}
	if (*cp == '"' || *cp == '\'')
		quote = *cp++;
	start = cp;
	if (quote)
		while (*cp && *cp != quote)
			cp++;
	else
		while (*cp && *cp != ' ' && *cp != '\t')
			cp++;
	if (*cp != '\0')
		*cp++ = '\0';
	*cpp = cp;
	return (start);
}

char *
nextline(fd)
	FILE *fd;
{
	char *cp;

	if (fgets(line, sizeof (line), fd) == NULL)
		return ((char *)0);
	cp = strchr(line, '\n');
	if (cp)
		*cp = '\0';
	return (line);
}

char *
newstr(cp)
	char *cp;
{
	if ((cp = strdup(cp ? cp : "")))
		return (cp);
	syslog(LOG_ERR, "strdup: %m");
	exit(EX_OSERR);
}

#ifdef OLD_SETPROCTITLE
void
inetd_setproctitle(a, s)
	char *a;
	int s;
{
	int size;
	char *cp;
	struct sockaddr_in sin;
	char buf[80];

	cp = Argv[0];
	size = sizeof(sin);
	if (getpeername(s, (struct sockaddr *)&sin, &size) == 0)
		(void) sprintf(buf, "-%s [%s]", a, inet_ntoa(sin.sin_addr));
	else
		(void) sprintf(buf, "-%s", a);
	strncpy(cp, buf, LastArg - cp);
	cp += strlen(cp);
	while (cp < LastArg)
		*cp++ = ' ';
}
#else
void
inetd_setproctitle(a, s)
	char *a;
	int s;
{
	int size;
	struct sockaddr_in sin;
	char buf[80];

	size = sizeof(sin);
	if (getpeername(s, (struct sockaddr *)&sin, &size) == 0)
		(void) sprintf(buf, "%s [%s]", a, inet_ntoa(sin.sin_addr));
	else
		(void) sprintf(buf, "%s", a);
	setproctitle("%s", buf);
}
#endif


/*
 * Internet services provided internally by inetd:
 */
#define	BUFSIZE	8192

/* ARGSUSED */
void
echo_stream(s, sep)		/* Echo service -- echo data back */
	int s;
	struct servtab *sep;
{
	char buffer[BUFSIZE];
	int i;

	inetd_setproctitle(sep->se_service, s);
	while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
	    write(s, buffer, i) > 0)
		;
	exit(0);
}

int check_loop(sin, sep)
	struct sockaddr_in *sin;
	struct servtab *sep;
{
	struct servtab *se2;

	for (se2 = servtab; se2; se2 = se2->se_next) {
		if (!se2->se_bi || se2->se_socktype != SOCK_DGRAM)
			continue;

		if (sin->sin_port == se2->se_ctrladdr.sin_port) {
			syslog(LOG_WARNING,
			       "%s/%s:%s/%s loop request REFUSED from %s",
			       sep->se_service, sep->se_proto,
			       se2->se_service, se2->se_proto,
			       inet_ntoa(sin->sin_addr));
			return 1;
		}
	}
	return 0;
}

/* ARGSUSED */
void
echo_dg(s, sep)			/* Echo service -- echo data back */
	int s;
	struct servtab *sep;
{
	char buffer[BUFSIZE];
	int i, size;
	struct sockaddr_in sin;

	size = sizeof(sin);
	if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
			  (struct sockaddr *)&sin, &size)) < 0)
		return;

	if (check_loop(&sin, sep))
		return;

	(void) sendto(s, buffer, i, 0, (struct sockaddr *)&sin,
		      sizeof(sin));
}

/* ARGSUSED */
void
discard_stream(s, sep)		/* Discard service -- ignore data */
	int s;
	struct servtab *sep;
{
	int ret;
	char buffer[BUFSIZE];

	inetd_setproctitle(sep->se_service, s);
	while (1) {
		while ((ret = read(s, buffer, sizeof(buffer))) > 0)
			;
		if (ret == 0 || errno != EINTR)
			break;
	}
	exit(0);
}

/* ARGSUSED */
void
discard_dg(s, sep)		/* Discard service -- ignore data */
	int s;
	struct servtab *sep;
{
	char buffer[BUFSIZE];

	(void) read(s, buffer, sizeof(buffer));
}

#include <ctype.h>
#define LINESIZ 72
char ring[128];
char *endring;

void
initring()
{
	int i;

	endring = ring;

	for (i = 0; i <= 128; ++i)
		if (isprint(i))
			*endring++ = i;
}

/* ARGSUSED */
void
chargen_stream(s, sep)		/* Character generator */
	int s;
	struct servtab *sep;
{
	int len;
	char *rs, text[LINESIZ+2];

	inetd_setproctitle(sep->se_service, s);

	if (!endring) {
		initring();
		rs = ring;
	}

	text[LINESIZ] = '\r';
	text[LINESIZ + 1] = '\n';
	for (rs = ring;;) {
		if ((len = endring - rs) >= LINESIZ)
			memmove(text, rs, LINESIZ);
		else {
			memmove(text, rs, len);
			memmove(text + len, ring, LINESIZ - len);
		}
		if (++rs == endring)
			rs = ring;
		if (write(s, text, sizeof(text)) != sizeof(text))
			break;
	}
	exit(0);
}

/* ARGSUSED */
void
chargen_dg(s, sep)		/* Character generator */
	int s;
	struct servtab *sep;
{
	struct sockaddr_in sin;
	static char *rs;
	int len, size;
	char text[LINESIZ+2];

	if (endring == 0) {
		initring();
		rs = ring;
	}

	size = sizeof(sin);
	if (recvfrom(s, text, sizeof(text), 0,
		     (struct sockaddr *)&sin, &size) < 0)
		return;

	if (check_loop(&sin, sep))
		return;

	if ((len = endring - rs) >= LINESIZ)
		memmove(text, rs, LINESIZ);
	else {
		memmove(text, rs, len);
		memmove(text + len, ring, LINESIZ - len);
	}
	if (++rs == endring)
		rs = ring;
	text[LINESIZ] = '\r';
	text[LINESIZ + 1] = '\n';
	(void) sendto(s, text, sizeof(text), 0,
		      (struct sockaddr *)&sin, sizeof(sin));
}

/*
 * Return a machine readable date and time, in the form of the
 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
 * returns the number of seconds since midnight, Jan 1, 1970,
 * we must add 2208988800 seconds to this figure to make up for
 * some seventy years Bell Labs was asleep.
 */

long
machtime()
{
	struct timeval tv;

	if (gettimeofday(&tv, (struct timezone *)0) < 0) {
		if (debug)
			warnx("unable to get time of day");
		return (0L);
	}
#define	OFFSET ((u_long)25567 * 24*60*60)
	return (htonl((long)(tv.tv_sec + OFFSET)));
#undef OFFSET
}

/* ARGSUSED */
void
machtime_stream(s, sep)
	int s;
	struct servtab *sep;
{
	long result;

	result = machtime();
	(void) write(s, (char *) &result, sizeof(result));
}

/* ARGSUSED */
void
machtime_dg(s, sep)
	int s;
	struct servtab *sep;
{
	long result;
	struct sockaddr_in sin;
	int size;

	size = sizeof(sin);
	if (recvfrom(s, (char *)&result, sizeof(result), 0,
		     (struct sockaddr *)&sin, &size) < 0)
		return;

	if (check_loop(&sin, sep))
		return;

	result = machtime();
	(void) sendto(s, (char *) &result, sizeof(result), 0,
		      (struct sockaddr *)&sin, sizeof(sin));
}

/* ARGSUSED */
void
daytime_stream(s, sep)		/* Return human-readable time of day */
	int s;
	struct servtab *sep;
{
	char buffer[256];
	time_t clock;

	clock = time((time_t *) 0);

	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
	(void) write(s, buffer, strlen(buffer));
}

/* ARGSUSED */
void
daytime_dg(s, sep)		/* Return human-readable time of day */
	int s;
	struct servtab *sep;
{
	char buffer[256];
	time_t clock;
	struct sockaddr_in sin;
	int size;

	clock = time((time_t *) 0);

	size = sizeof(sin);
	if (recvfrom(s, buffer, sizeof(buffer), 0,
		     (struct sockaddr *)&sin, &size) < 0)
		return;

	if (check_loop(&sin, sep))
		return;

	(void) sprintf(buffer, "%.24s\r\n", ctime(&clock));
	(void) sendto(s, buffer, strlen(buffer), 0,
		      (struct sockaddr *)&sin, sizeof(sin));
}

/*
 * print_service:
 *	Dump relevant information to stderr
 */
void
print_service(action, sep)
	char *action;
	struct servtab *sep;
{
	fprintf(stderr,
#ifdef LOGIN_CAP
	    "%s: %s proto=%s accept=%d max=%d user=%s group=%s class=%s builtin=%x server=%s\n",
#else
	    "%s: %s proto=%s accept=%d max=%d user=%s group=%s builtin=%x server=%s\n",
#endif
	    action, sep->se_service, sep->se_proto,
	    sep->se_accept, sep->se_maxchild, sep->se_user, sep->se_group,
#ifdef LOGIN_CAP
	    sep->se_class,
#endif
	    (int)sep->se_bi, sep->se_server);
}

/*
 *  Based on TCPMUX.C by Mark K. Lottor November 1988
 *  sri-nic::ps:<mkl>tcpmux.c
 */


static int		/* # of characters upto \r,\n or \0 */
getline(fd, buf, len)
	int fd;
	char *buf;
	int len;
{
	int count = 0, n;
	struct sigaction sa;

	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	sa.sa_handler = SIG_DFL;
	sigaction(SIGALRM, &sa, (struct sigaction *)0);
	do {
		alarm(10);
		n = read(fd, buf, len-count);
		alarm(0);
		if (n == 0)
			return (count);
		if (n < 0)
			return (-1);
		while (--n >= 0) {
			if (*buf == '\r' || *buf == '\n' || *buf == '\0')
				return (count);
			count++;
			buf++;
		}
	} while (count < len);
	return (count);
}

#define MAX_SERV_LEN	(256+2)		/* 2 bytes for \r\n */

#define strwrite(fd, buf)	(void) write(fd, buf, sizeof(buf)-1)

struct servtab *
tcpmux(s)
	int s;
{
	struct servtab *sep;
	char service[MAX_SERV_LEN+1];
	int len;

	/* Get requested service name */
	if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
		strwrite(s, "-Error reading service name\r\n");
		return (NULL);
	}
	service[len] = '\0';

	if (debug)
		warnx("tcpmux: someone wants %s", service);

	/*
	 * Help is a required command, and lists available services,
	 * one per line.
	 */
	if (!strcasecmp(service, "help")) {
		for (sep = servtab; sep; sep = sep->se_next) {
			if (!ISMUX(sep))
				continue;
			(void)write(s,sep->se_service,strlen(sep->se_service));
			strwrite(s, "\r\n");
		}
		return (NULL);
	}

	/* Try matching a service in inetd.conf with the request */
	for (sep = servtab; sep; sep = sep->se_next) {
		if (!ISMUX(sep))
			continue;
		if (!strcasecmp(service, sep->se_service)) {
			if (ISMUXPLUS(sep)) {
				strwrite(s, "+Go\r\n");
			}
			return (sep);
		}
	}
	strwrite(s, "-Service not available\r\n");
	return (NULL);
}

#define CPMHSIZE	256
#define CPMHMASK	(CPMHSIZE-1)
#define CHTGRAN		10
#define CHTSIZE		6

typedef struct CTime {
	unsigned long 	ct_Ticks;
	int		ct_Count;
} CTime;

typedef struct CHash {
	struct in_addr	ch_Addr;
	time_t		ch_LTime;
	char		*ch_Service;
	CTime		ch_Times[CHTSIZE];
} CHash;

CHash	CHashAry[CPMHSIZE];

int
cpmip(sep, ctrl)
	struct servtab *sep;
	int ctrl;
{
	struct sockaddr_in rsin;
	int rsinLen = sizeof(rsin);
	int r = 0;

	/*
	 * If getpeername() fails, just let it through (if logging is
	 * enabled the condition is caught elsewhere)
	 */

	if (sep->se_maxcpm > 0 && 
	    getpeername(ctrl, (struct sockaddr *)&rsin, &rsinLen) == 0 ) {
		time_t t = time(NULL);
		int hv = 0xABC3D20F;
		int i;
		int cnt = 0;
		CHash *chBest = NULL;
		unsigned int ticks = t / CHTGRAN;

		{
			char *p;
			int i;

			for (i = 0, p = (char *)&rsin.sin_addr; 
			    i < sizeof(rsin.sin_addr); 
			    ++i, ++p) {
				hv = (hv << 5) ^ (hv >> 23) ^ *p;
			}
			hv = (hv ^ (hv >> 16));
		}
		for (i = 0; i < 5; ++i) {
			CHash *ch = &CHashAry[(hv + i) & CPMHMASK];

			if (rsin.sin_addr.s_addr == ch->ch_Addr.s_addr &&
			    ch->ch_Service && strcmp(sep->se_service,
			    ch->ch_Service) == 0) {
				chBest = ch;
				break;
			}
			if (chBest == NULL || ch->ch_LTime == 0 || 
			    ch->ch_LTime < chBest->ch_LTime) {
				chBest = ch;
			}
		}
		if (rsin.sin_addr.s_addr != chBest->ch_Addr.s_addr ||
		    chBest->ch_Service == NULL ||
		    strcmp(sep->se_service, chBest->ch_Service) != 0) {
			chBest->ch_Addr = rsin.sin_addr;
			if (chBest->ch_Service)
				free(chBest->ch_Service);
			chBest->ch_Service = strdup(sep->se_service);
			bzero(chBest->ch_Times, sizeof(chBest->ch_Times));
		} 
		chBest->ch_LTime = t;
		{
			CTime *ct = &chBest->ch_Times[ticks % CHTSIZE];
			if (ct->ct_Ticks != ticks) {
				ct->ct_Ticks = ticks;
				ct->ct_Count = 0;
			}
			++ct->ct_Count;
		}
		for (i = 0; i < CHTSIZE; ++i) {
			CTime *ct = &chBest->ch_Times[i];
			if (ct->ct_Ticks <= ticks &&
			    ct->ct_Ticks >= ticks - CHTSIZE) {
				cnt += ct->ct_Count;
			}
		}
		if (cnt * (CHTSIZE * CHTGRAN) / 60 > sep->se_maxcpm) {
			r = -1;
			syslog(LOG_ERR,
			    "%s from %s exceeded counts/min (limit %d/min)",
			    sep->se_service, inet_ntoa(rsin.sin_addr), 
			    sep->se_maxcpm);
		}
	}
	return(r);
}
----- inetd.8 ----- cut here -----------------------------------
.\" Copyright (c) 1985, 1991, 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.
.\"
.\"     from: @(#)inetd.8	8.3 (Berkeley) 4/13/94
.\"	$Id: inetd.8,v 1.9.2.6 1998/07/18 11:10:23 jkh Exp $
.\"
.Dd October 7, 1998
.Dt INETD 8
.Os BSD 4.4
.Sh NAME
.Nm inetd
.Nd internet
.Dq super-server
.Sh SYNOPSIS
.Nm inetd
.Op Fl d
.Op Fl l
.Op Fl X
.Op Fl c Ar maximum
.Op Fl C Ar rate
.Op Fl a Ar address
.Op Fl p Ar filename
.Op Fl R Ar rate
.Op Ar configuration file
.Sh DESCRIPTION
The
.Nm
program
should be run at boot time by
.Pa /etc/rc
(see
.Xr rc 8 ) .
It then listens for connections on certain
internet sockets.  When a connection is found on one
of its sockets, it decides what service the socket
corresponds to, and invokes a program to service the request.
The server program is invoked with the service socket
as its standard input, output and error descriptors.
After the program is
finished,
.Nm
continues to listen on the socket (except in some cases which
will be described below).  Essentially,
.Nm
allows running one daemon to invoke several others,
reducing load on the system.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl d
Turn on debugging.
.It Fl l
Turn on logging.
.It Fl X
Enable the extended config file format.
.It Fl c Ar maximum
Specify the default maximum number of services that can be invoked.
May be overridden on a per-service basis with the "max-child"
parameter.
.It Fl C Ar rate
Specify the default maximum number of times a service can be invoked
from a single IP address in one minute; the default is unlimited.
May be overridden on a per-service basis with the
"max-connections-per-ip-per-minute" parameter.
.It Fl R Ar rate
Specify the maximum number of times a service can be invoked
in one minute; the default is 256.
.It Fl a
Specify a specific IP address to bind to.
.It Fl p
Specify an alternate file in which to store the process ID.
.El
.Pp
Upon execution,
.Nm
reads its configuration information from a configuration
file which, by default, is
.Pa /etc/inetd.conf .
There must be an entry for each field of the configuration
file, with entries for each field separated by a tab or
a space.  Comments are denoted by a ``#'' at the beginning
of a line.  There must be an entry for each field.  The
fields of the configuration file are as follows:
.Pp
.Bd -unfilled -offset indent -compact
service name
socket type
protocol
{wait|nowait}[/max-child[/max-connections-per-ip-per-minute]]
user[:group][/login-class]
server program
server program arguments
.Ed
.Pp
If the 
.Fl X
option is given, then each entry has an additional initial field,
which is the numeric IP address to which the listening socket should
be bound. The special value `any' causes the socket to be bound to
INADDR_ANY (the same as if the 
.Fl X
option was not given).
.Pp
To specify an
.No Tn "ONC RPC" Ns -based
service, the entry would contain these fields:
.Pp
.Bd -unfilled -offset indent -compact
service name/version
socket type
rpc/protocol
user[:group][/login-class]
server program
server program arguments
.Ed
.Pp
There are two types of services that 
.Nm
can start: standard and TCPMUX.
A standard service has a well-known port assigned to it;
it may be a service that implements an official Internet standard or is a
BSD-specific service.
As described in 
.Tn RFC 1078 ,
TCPMUX services are nonstandard services that do not have a 
well-known port assigned to them.
They are invoked from
.Nm
when a program connects to the
.Dq tcpmux
well-known port and specifies
the service name.  
This feature is useful for adding locally-developed servers.
TCPMUX requests are only accepted when the multiplexor service itself
is enabled, above and beyond and specific TCPMUX-based servers; see the
discussion of internal services below.
.Pp
The
.Em service-name
entry is the name of a valid service in
the file
.Pa /etc/services .
For
.Dq internal
services (discussed below), the service
name
.Em must
be the official name of the service (that is, the first entry in
.Pa /etc/services ) .
When used to specify an
.No Tn "ONC RPC" Ns -based
service, this field is a valid RPC service name in
the file
.Pa /etc/rpc . 
The part on the right of the 
.Dq /
is the RPC version number. This
can simply be a single numeric argument or a range of versions.
A range is bounded by the low version to the high version - 
.Dq rusers/1-3 .
For TCPMUX services, the value of the
.Em service-name
field consists of the string
.Dq tcpmux
followed by a slash and the
locally-chosen service name. 
The service names listed in 
.Pa /etc/services
and the name 
.Dq help
are reserved.
Try to choose unique names for your TCPMUX services by prefixing them with
your organization's name and suffixing them with a version number.
.Pp
The
.Em socket-type
should be one of
.Dq stream ,
.Dq dgram ,
.Dq raw ,
.Dq rdm ,
or
.Dq seqpacket ,
depending on whether the socket is a stream, datagram, raw,
reliably delivered message, or sequenced packet socket.
TCPMUX services must use 
.Dq stream .
.Pp
The
.Em protocol
must be a valid protocol as given in
.Pa /etc/protocols .
Examples might be
.Dq tcp
or
.Dq udp .
If it is desired that the service is reachable via T/TCP, one should
specify
.Dq tcp/ttcp .
Rpc based services are specified with the 
.Dq rpc/tcp
or 
.Dq rpc/udp 
service type.
TCPMUX services must use 
.Dq tcp .
.Pp
The
.Em wait/nowait
entry specifies whether the server that is invoked by
.Nm
will take over
the socket associated with the service access point, and thus whether
.Nm
should wait for the server to exit before listening for new service
requests.
Datagram servers must use
.Dq wait ,
as they are always invoked with the original datagram socket bound
to the specified service address.
These servers must read at least one datagram from the socket
before exiting.
If a datagram server connects
to its peer, freeing the socket so
.Nm
can received further messages on the socket, it is said to be
a
.Dq multi-threaded
server;
it should read one datagram from the socket and create a new socket
connected to the peer.
It should fork, and the parent should then exit
to allow
.Nm
to check for new service requests to spawn new servers.
Datagram servers which process all incoming datagrams
on a socket and eventually time out are said to be
.Dq single-threaded .
.Xr Comsat 8 ,
.Pq Xr biff 1
and
.Xr talkd 8
are both examples of the latter type of
datagram server.
.Xr Tftpd 8
is an example of a multi-threaded datagram server.
.Pp
Servers using stream sockets generally are multi-threaded and
use the
.Dq nowait
entry.
Connection requests for these services are accepted by
.Nm inetd ,
and the server is given only the newly-accepted socket connected
to a client of the service.
Most stream-based services operate in this manner.
Stream-based servers that use
.Dq wait
are started with the listening service socket, and must accept
at least one connection request before exiting.
Such a server would normally accept and process incoming connection
requests until a timeout.
TCPMUX services must use 
.Dq nowait .
.Pp
The maximum number of outstanding child processes (or ``threads'')
for a ``nowait'' service may be explicitly specified by appending a
``/'' followed by the number to the ``nowait'' keyword. Normally
(or if a value of zero is specified) there is no maximum. Otherwise,
once the maximum is reached, further connection attempts will be
queued up until an existing child process exits. This also works
in the case of ``wait'' mode, although a value other than one (the
default) might not make sense in some cases.
You can also specify the maximum number of connections per minute
for a given IP address by appending
a ``/'' followed by the number to the maximum number of
outstanding child processes. Once the maximum is reached, further
connections from this IP address will be dropped until the end of the
minute.
.Pp
The
.Em user
entry should contain the user name of the user as whom the server
should run.  This allows for servers to be given less permission
than root.
Optional
.Em group
part separated by ``:'' allows to specify group name different
than default group for this user.
Optional
.Em login-class
part separated by ``/'' allows to specify login class different
than default ``daemon'' login class.
.Pp
The
.Em server-program
entry should contain the pathname of the program which is to be
executed by
.Nm
when a request is found on its socket.  If
.Nm
provides this service internally, this entry should
be
.Dq internal .
.Pp
The
.Em server program arguments
should be just as arguments
normally are, starting with argv[0], which is the name of
the program.  If the service is provided internally, the
word
.Dq internal
should take the place of this entry.
.Pp
The
.Nm
program
provides several
.Dq trivial
services internally by use of
routines within itself.  These services are
.Dq echo ,
.Dq discard ,
.Dq chargen
(character generator),
.Dq daytime
(human readable time), and
.Dq time
(machine readable time, in the form of the number of seconds since
midnight, January 1, 1900).  All of these services are available in
both TCP and UDP versions; the UDP versions will refuse service if the
request specifies a reply port corresponding to any internal service.
(This is done as a defense against looping attacks; the remote IP address
is logged.)
For details of these services, consult the
appropriate
.Tn RFC
document.
.Pp
The TCPMUX-demultiplexing service is also implemented as an internal service.
For any TCPMUX-based service to function, the following line must be included
in
.Pa inetd.conf :
.Bd -literal -offset indent
tcpmux	stream	tcp	nowait	root	internal
.Ed
.Pp
When given the
.Fl l
option
.Nm
will log an entry to syslog each time an 
.Xr accept 2 
is made, which notes the
service selected and the IP-number of the remote requestor.
.Pp
The
.Nm
program
rereads its configuration file when it receives a hangup signal,
.Dv SIGHUP .
Services may be added, deleted or modified when the configuration file
is reread.
Except when started in debugging mode,
.Nm
records its process ID in the file
.Pa /var/run/inetd.pid
to assist in reconfiguration.
.Sh TCPMUX
.Pp
.Tn RFC 1078 
describes the TCPMUX protocol:
``A TCP client connects to a foreign host on TCP port 1.  It sends the
service name followed by a carriage-return line-feed <CRLF>.  The
service name is never case sensitive.  The server replies with a
single character indicating positive (+) or negative (\-)
acknowledgment, immediately followed by an optional message of
explanation, terminated with a <CRLF>.  If the reply was positive,
the selected protocol begins; otherwise the connection is closed.''
The program is passed the TCP connection as file descriptors 0 and 1.
.Pp
If the TCPMUX service name begins with a ``+'',
.Nm
returns the positive reply for the program.
This allows you to invoke programs that use stdin/stdout
without putting any special server code in them.
.Pp
The special service name
.Dq help
causes
.Nm
to list TCPMUX services in
.Pa inetd.conf .
.Sh "FILES"
.Bl -tag -width /var/run/inetd.pid -compact
.It Pa /etc/inetd.conf
configuration file.
.It Pa /etc/rpc
translation of service names to RPC program numbers.
.It Pa /etc/services
translation of service names to port numbers.
.It Pa /var/run/inetd.pid
the pid of the currently running
.Nm inetd .
.El
.Sh "EXAMPLES"
.Pp
Here are several example service entries for the various types of services:
.Bd -literal
ftp          stream  tcp   nowait root  /usr/libexec/ftpd        ftpd -l
ntalk        dgram   udp   wait   root  /usr/libexec/ntalkd      ntalkd
tcpmux/+date stream  tcp   nowait guest /bin/date                date
tcpmux/phonebook stream tcp nowait guest /usr/local/bin/phonebook phonebook
rstatd/1-3   dgram   rpc/udp wait root  /usr/libexec/rpc.rstatd  rpc.rstatd
.Ed
.Sh "ERROR MESSAGES"
The
.Nm
server
logs error messages using
.Xr syslog 3 .
Important error messages and their explanations are:
.Pp
.Bl -ohang -compact
.It Xo
.Ar service Ns / Ns Ar protocol
.No " server failing (looping), service terminated."
.Xc
The number of requests for the specified service in the past minute
exceeded the limit. The limit exists to prevent a broken program
or a malicious user from swamping the system.
This message may occur for several reasons:
.Bl -enum -offset indent
.It
There are many hosts requesting the service within a short time period.
.It
A broken client program is requesting the service too frequently.
.It
A malicious user is running a program to invoke the service in
a denial-of-service attack.
.It
The invoked service program has an error that causes clients
to retry quickly.
.El
.Pp
Use the
.Fl R Ar rate
option,
as described above, to change the rate limit.
Once the limit is reached, the service will be
reenabled automatically in 10 minutes.
.Pp
.It Xo
.Ar service Ns / Ns Ar protocol :
.No \&No such user
.Ar user ,
.No service ignored
.Xc
.It Xo
.Ar service Ns / Ns Ar protocol :
.No getpwnam :
.Ar user :
.No \&No such user
.Xc
No entry for 
.Ar user
exists in the 
.Xr passwd 5
database. The first message
occurs when
.Nm
(re)reads the configuration file. The second message occurs when the
service is invoked.
.Pp
.It Xo
.Ar service :
.No can't set uid
.Ar uid
.Xc
.It Xo
.Ar service :
.No can't set gid
.Ar gid
.Xc
The user or group ID for the entry's 
.Ar user
field is invalid.
.Pp
.It "setsockopt(SO_PRIVSTATE): Operation not supported"
The
.Nm
program attempted to renounce the privileged state associated with a
socket but was unable to.
.El
.Sh SEE ALSO
.Xr login.conf 5 ,
.Xr passwd 5 ,
.Xr rpc 5 ,
.Xr services 5 ,
.Xr comsat 8 ,
.Xr fingerd 8 ,
.Xr ftpd 8 ,
.Xr portmap 8 ,
.Xr rexecd 8 ,
.Xr rlogind 8 ,
.Xr rshd 8 ,
.Xr telnetd 8 ,
.Xr tftpd 8
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
TCPMUX is based on code and documentation by Mark Lottor.
Support for
.Tn "ONC RPC"
based services is modeled after that
provided by
.Tn SunOS
4.1.
	
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