daemon.c

早期freebsd实现

/*
 * Copyright (c) 1983 Eric P. Allman
 * Copyright (c) 1988, 1993
 *	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.
 */

#include <errno.h>
#include "sendmail.h"

#ifndef lint
#ifdef DAEMON
static char sccsid[] = "@(#)daemon.c	8.48 (Berkeley) 4/18/94 (with daemon mode)";
#else
static char sccsid[] = "@(#)daemon.c	8.48 (Berkeley) 4/18/94 (without daemon mode)";
#endif
#endif /* not lint */

#ifdef DAEMON

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

#if NAMED_BIND
# include <arpa/nameser.h>
# include <resolv.h>
#endif

/*
**  DAEMON.C -- routines to use when running as a daemon.
**
**	This entire file is highly dependent on the 4.2 BSD
**	interprocess communication primitives.  No attempt has
**	been made to make this file portable to Version 7,
**	Version 6, MPX files, etc.  If you should try such a
**	thing yourself, I recommend chucking the entire file
**	and starting from scratch.  Basic semantics are:
**
**	getrequests()
**		Opens a port and initiates a connection.
**		Returns in a child.  Must set InChannel and
**		OutChannel appropriately.
**	clrdaemon()
**		Close any open files associated with getting
**		the connection; this is used when running the queue,
**		etc., to avoid having extra file descriptors during
**		the queue run and to avoid confusing the network
**		code (if it cares).
**	makeconnection(host, port, outfile, infile, usesecureport)
**		Make a connection to the named host on the given
**		port.  Set *outfile and *infile to the files
**		appropriate for communication.  Returns zero on
**		success, else an exit status describing the
**		error.
**	host_map_lookup(map, hbuf, avp, pstat)
**		Convert the entry in hbuf into a canonical form.
*/
/*
**  GETREQUESTS -- open mail IPC port and get requests.
**
**	Parameters:
**		none.
**
**	Returns:
**		none.
**
**	Side Effects:
**		Waits until some interesting activity occurs.  When
**		it does, a child is created to process it, and the
**		parent waits for completion.  Return from this
**		routine is always in the child.  The file pointers
**		"InChannel" and "OutChannel" should be set to point
**		to the communication channel.
*/

int		DaemonSocket	= -1;		/* fd describing socket */
SOCKADDR	DaemonAddr;			/* socket for incoming */
int		ListenQueueSize = 10;		/* size of listen queue */
int		TcpRcvBufferSize = 0;		/* size of TCP receive buffer */
int		TcpSndBufferSize = 0;		/* size of TCP send buffer */

getrequests()
{
	int t;
	bool refusingconnections = TRUE;
	FILE *pidf;
	int socksize;
#ifdef XDEBUG
	bool j_has_dot;
#endif
	extern void reapchild();

	/*
	**  Set up the address for the mailer.
	*/

	if (DaemonAddr.sin.sin_family == 0)
		DaemonAddr.sin.sin_family = AF_INET;
	if (DaemonAddr.sin.sin_addr.s_addr == 0)
		DaemonAddr.sin.sin_addr.s_addr = INADDR_ANY;
	if (DaemonAddr.sin.sin_port == 0)
	{
		register struct servent *sp;

		sp = getservbyname("smtp", "tcp");
		if (sp == NULL)
		{
			syserr("554 service \"smtp\" unknown");
			DaemonAddr.sin.sin_port = htons(25);
		}
		else
			DaemonAddr.sin.sin_port = sp->s_port;
	}

	/*
	**  Try to actually open the connection.
	*/

	if (tTd(15, 1))
		printf("getrequests: port 0x%x\n", DaemonAddr.sin.sin_port);

	/* get a socket for the SMTP connection */
	socksize = opendaemonsocket(TRUE);

	(void) setsignal(SIGCHLD, reapchild);

	/* write the pid to the log file for posterity */
	pidf = fopen(PidFile, "w");
	if (pidf != NULL)
	{
		extern char *CommandLineArgs;

		/* write the process id on line 1 */
		fprintf(pidf, "%d\n", getpid());

		/* line 2 contains all command line flags */
		fprintf(pidf, "%s\n", CommandLineArgs);

		/* flush and close */
		fclose(pidf);
	}

#ifdef XDEBUG
	{
		char jbuf[MAXHOSTNAMELEN];

		expand("\201j", jbuf, &jbuf[sizeof jbuf - 1], CurEnv);
		j_has_dot = strchr(jbuf, '.') != NULL;
	}
#endif

	if (tTd(15, 1))
		printf("getrequests: %d\n", DaemonSocket);

	for (;;)
	{
		register int pid;
		auto int lotherend;
		extern bool refuseconnections();

		/* see if we are rejecting connections */
		CurrentLA = getla();
		if (refuseconnections())
		{
			if (DaemonSocket >= 0)
			{
				/* close socket so peer will fail quickly */
				(void) close(DaemonSocket);
				DaemonSocket = -1;
			}
			refusingconnections = TRUE;
			setproctitle("rejecting connections: load average: %d",
				CurrentLA);
			sleep(15);
			continue;
		}

		if (refusingconnections)
		{
			/* start listening again */
			(void) opendaemonsocket(FALSE);
			setproctitle("accepting connections");
			refusingconnections = FALSE;
		}

#ifdef XDEBUG
		/* check for disaster */
		{
			register STAB *s;
			char jbuf[MAXHOSTNAMELEN];

			expand("\201j", jbuf, &jbuf[sizeof jbuf - 1], CurEnv);
			if ((s = stab(jbuf, ST_CLASS, ST_FIND)) == NULL ||
			    !bitnset('w', s->s_class))
			{
				dumpstate("daemon lost $j");
				syslog(LOG_ALERT, "daemon process doesn't have $j in $=w; see syslog");
				abort();
			}
			else if (j_has_dot && strchr(jbuf, '.') == NULL)
			{
				dumpstate("daemon $j lost dot");
				syslog(LOG_ALERT, "daemon process $j lost dot; see syslog");
				abort();
			}
		}
#endif

		/* wait for a connection */
		do
		{
			errno = 0;
			lotherend = socksize;
			t = accept(DaemonSocket,
			    (struct sockaddr *)&RealHostAddr, &lotherend);
		} while (t < 0 && errno == EINTR);
		if (t < 0)
		{
			syserr("getrequests: accept");
			sleep(5);
			continue;
		}

		/*
		**  Create a subprocess to process the mail.
		*/

		if (tTd(15, 2))
			printf("getrequests: forking (fd = %d)\n", t);

		pid = fork();
		if (pid < 0)
		{
			syserr("daemon: cannot fork");
			sleep(10);
			(void) close(t);
			continue;
		}

		if (pid == 0)
		{
			char *p;
			extern char *hostnamebyanyaddr();

			/*
			**  CHILD -- return to caller.
			**	Collect verified idea of sending host.
			**	Verify calling user id if possible here.
			*/

			(void) setsignal(SIGCHLD, SIG_DFL);
			DisConnected = FALSE;

			setproctitle("startup with %s",
				anynet_ntoa(&RealHostAddr));

			/* determine host name */
			p = hostnamebyanyaddr(&RealHostAddr);
			RealHostName = newstr(p);
			setproctitle("startup with %s", p);

#ifdef LOG
			if (LogLevel > 11)
			{
				/* log connection information */
				syslog(LOG_INFO, "connect from %s (%s)",
					RealHostName, anynet_ntoa(&RealHostAddr));
			}
#endif

			(void) close(DaemonSocket);
			if ((InChannel = fdopen(t, "r")) == NULL ||
			    (t = dup(t)) < 0 ||
			    (OutChannel = fdopen(t, "w")) == NULL)
			{
				syserr("cannot open SMTP server channel, fd=%d", t);
				exit(0);
			}

			/* should we check for illegal connection here? XXX */
#ifdef XLA
			if (!xla_host_ok(RealHostName))
			{
				message("421 Too many SMTP sessions for this host");
				exit(0);
			}
#endif

			if (tTd(15, 2))
				printf("getreq: returning\n");
			return;
		}

		/* close the port so that others will hang (for a while) */
		(void) close(t);
	}
	/*NOTREACHED*/
}
/*
**  OPENDAEMONSOCKET -- open the SMTP socket
**
**	Deals with setting all appropriate options.  DaemonAddr must
**	be set up in advance.
**
**	Parameters:
**		firsttime -- set if this is the initial open.
**
**	Returns:
**		Size in bytes of the daemon socket addr.
**
**	Side Effects:
**		Leaves DaemonSocket set to the open socket.
**		Exits if the socket cannot be created.
*/

#define MAXOPENTRIES	10	/* maximum number of tries to open connection */

int
opendaemonsocket(firsttime)
	bool firsttime;
{
	int on = 1;
	int socksize;
	int ntries = 0;
	int saveerrno;

	if (tTd(15, 2))
		printf("opendaemonsocket()\n");

	do
	{
		if (ntries > 0)
			sleep(5);
		if (firsttime || DaemonSocket < 0)
		{
			DaemonSocket = socket(DaemonAddr.sa.sa_family, SOCK_STREAM, 0);
			if (DaemonSocket < 0)
			{
				/* probably another daemon already */
				saveerrno = errno;
				syserr("opendaemonsocket: can't create server SMTP socket");
			  severe:
# ifdef LOG
				if (LogLevel > 0)
					syslog(LOG_ALERT, "problem creating SMTP socket");
# endif /* LOG */
				DaemonSocket = -1;
				continue;
			}

			/* turn on network debugging? */
			if (tTd(15, 101))
				(void) setsockopt(DaemonSocket, SOL_SOCKET,
						  SO_DEBUG, (char *)&on,
						  sizeof on);

			(void) setsockopt(DaemonSocket, SOL_SOCKET,
					  SO_REUSEADDR, (char *)&on, sizeof on);
			(void) setsockopt(DaemonSocket, SOL_SOCKET,
					  SO_KEEPALIVE, (char *)&on, sizeof on);

#ifdef SO_RCVBUF
			if (TcpRcvBufferSize > 0)
			{
				if (setsockopt(DaemonSocket, SOL_SOCKET,
					       SO_RCVBUF,
					       (char *) &TcpRcvBufferSize,
					       sizeof(TcpRcvBufferSize)) < 0)
					syserr("getrequests: setsockopt(SO_RCVBUF)");
			}
#endif

			switch (DaemonAddr.sa.sa_family)
			{
# ifdef NETINET
			  case AF_INET:
				socksize = sizeof DaemonAddr.sin;
				break;
# endif

# ifdef NETISO
			  case AF_ISO:
				socksize = sizeof DaemonAddr.siso;
				break;
# endif

			  default:
				socksize = sizeof DaemonAddr;
				break;
			}

			if (bind(DaemonSocket, &DaemonAddr.sa, socksize) < 0)
			{
				saveerrno = errno;
				syserr("getrequests: cannot bind");
				(void) close(DaemonSocket);
				goto severe;
			}
		}
		if (!firsttime && listen(DaemonSocket, ListenQueueSize) < 0)
		{
			saveerrno = errno;
			syserr("getrequests: cannot listen");
			(void) close(DaemonSocket);
			goto severe;
		}
		return socksize;
	} while (ntries++ < MAXOPENTRIES && transienterror(saveerrno));
	finis();
}
/*
**  CLRDAEMON -- reset the daemon connection
**
**	Parameters:
**		none.
**
**	Returns:
**		none.
**
**	Side Effects:
**		releases any resources used by the passive daemon.
*/

clrdaemon()
{
	if (DaemonSocket >= 0)
		(void) close(DaemonSocket);
	DaemonSocket = -1;
}
/*
**  SETDAEMONOPTIONS -- set options for running the daemon
**
**	Parameters:
**		p -- the options line.
**
**	Returns:
**		none.
*/

setdaemonoptions(p)
	register char *p;
{
	if (DaemonAddr.sa.sa_family == AF_UNSPEC)
		DaemonAddr.sa.sa_family = AF_INET;

	while (p != NULL)
	{
		register char *f;
		register char *v;

		while (isascii(*p) && isspace(*p))
			p++;
		if (*p == '\0')
			break;
		f = p;
		p = strchr(p, ',');
		if (p != NULL)
			*p++ = '\0';
		v = strchr(f, '=');
		if (v == NULL)
			continue;
		while (isascii(*++v) && isspace(*v))
			continue;

		switch (*f)
		{
		  case 'F':		/* address family */
			if (isascii(*v) && isdigit(*v))
				DaemonAddr.sa.sa_family = atoi(v);
#ifdef NETINET
			else if (strcasecmp(v, "inet") == 0)
				DaemonAddr.sa.sa_family = AF_INET;
#endif
#ifdef NETISO
			else if (strcasecmp(v, "iso") == 0)
				DaemonAddr.sa.sa_family = AF_ISO;
#endif
#ifdef NETNS
			else if (strcasecmp(v, "ns") == 0)
				DaemonAddr.sa.sa_family = AF_NS;
#endif
#ifdef NETX25
			else if (strcasecmp(v, "x.25") == 0)
				DaemonAddr.sa.sa_family = AF_CCITT;
#endif
			else
				syserr("554 Unknown address family %s in Family=option", v);
			break;