daemon.c

操作系统SunOS 4.1.3版本的源码

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 *
 *  Sendmail
 *  Copyright (c) 1983  Eric P. Allman
 *  Berkeley, California
 */

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

#ifdef DAEMON
#include "netdb.h"
#include <sys/wait.h>
#include <sys/param.h>
#include <net/if.h>
#include <sys/sockio.h>

SCCSID(@(#)daemon.c 1.1 92/07/30 SMI (with daemon mode)); /* from UCB 5.25 4/1/88*/

/*
**  DAEMON.C -- routines to use when running as a daemon.
**
**	This entire file is highly dependent on the 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)
**		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 and errno describing the
**		error.
**	maphostname(hbuf, hbufsize)
**		Convert the entry in hbuf into a canonical form.  It
**		may not be larger than hbufsize.
**	lookuphost(host)
**		Look up the host to determine an address.  Return
**		the address of a struct hostinfo about the host, which
**		may be modified by the caller if desired.
**	closeconnection(fd)
**		Marks the host which we connected to via file desc 'fd'
**		as closed, so we won't try to reuse the connection.
**		Note that this does not actually close the file
**		descriptor.  That's the caller's responsibility.
*/

static struct hostinfo *host_from_fd[NOFILE];	/* Host entry for each */


static setuphost(sp, hp)
    STAB *sp;
    struct hostent *hp;
  {
# if BSD >= 43
    int i;
    for (i= 0; i < MAXMXHOSTS && *hp->h_addr_list; i++)
	sp->s_value.sv_host.h_addrlist[ i ] = 
		*(struct in_addr *)(*hp->h_addr_list++);
    sp->s_value.sv_host.h_addrlist[ i ].s_addr = INADDR_ANY;
# else 
    sp->s_value.sv_host.h_addrlist[ 0 ] = *(struct in_addr *)(hp->h_addr);
    sp->s_value.sv_host.h_addrlist[ 1 ].s_addr = INADDR_ANY;
# endif
  }

static jmp_buf NameTimeout;
time_t nametime = 90;		/* seconds to wait for name server */

nametimeout()  {longjmp(NameTimeout, 1);}

/*
**  LOOKUPHOST -- determine host address and other remembered info.
**
**	Parameters:
**		host -- a char * providing a host name or [a.b.c.d].
**
**	Returns:
**		The address of a struct hostinfo for this host.
**		The caller may modify h_fd, h_down, and h_open in
**		this structure.  h_addr and h_exists should not be
**		modified.
**
**	Side Effects:
**		If the hostname has previously been looked up, the
**		existing symbol table entry is returned immediately.
**		Otherwise, a new symbol table entry is created, 
**		a system-dependent hostname->address lookup is done,
**		and the new entry is returned.
**
**		Note that for information to be remembered in the
**		symbol table, the process must do several lookups
**		without forking and exiting.
*/
struct hostinfo *
lookuphost(host)
	char *host;			/* Host name */
{
	register struct hostent *hp = (struct hostent *)NULL;
	extern char *inet_ntoa();
	STAB	*sp;			/* Symbol table entry */
	EVENT *ev;

	sp = stab(host, ST_HOST, ST_ENTER);
	if (sp->s_value.sv_host.h_valid) {
		AlreadyKnown = sp->s_value.sv_host.h_down;
		return &sp->s_value.sv_host;
	}

	/*
	**  Create a new symbol table entry.  Initially it is cleared,
	**  thus h_exists is 0.  Ditto for the other flags.
	**  Then look up the address for the host.
	**	Accept "[a.b.c.d]" syntax for host name.
	*/
	sp->s_value.sv_host.h_valid = 1;
	if (host[0] == '[')
	{
		long hid;
		register char *p = index(host, ']');

		if (p != NULL)
		{
			*p = '\0';
			hid = inet_addr(&host[1]);
			*p = ']';
		}
		if (p == NULL || hid == -1)
		{
			sp->s_value.sv_host.h_exists = 0;
		}
		else
		{
			sp->s_value.sv_host.h_addrlist[0].s_addr = hid;
			sp->s_value.sv_host.h_index = 0;
			sp->s_value.sv_host.h_exists = 1;
		}
		return &sp->s_value.sv_host;		/* Return [] entry */
	}

	if (setjmp(NameTimeout) != 0) {
		sp->s_value.sv_host.h_exists = 1;
		sp->s_value.sv_host.h_down = 1;
		sp->s_value.sv_host.h_errno = ENAMESER;
		return &sp->s_value.sv_host;
	}
	ev = setevent(nametime, nametimeout, 0);
	hp = gethostbyname(host);
	if (hp != NULL && hp->h_addrtype == AF_INET)
	{
		setuphost(sp, hp);
		sp->s_value.sv_host.h_index = 0;
		sp->s_value.sv_host.h_exists = 1;
	}
   /*
    * The gethostbyname failed -- in 4.2BSD we just return
    * a hard error.  4.3BSD gives us more infomation on the failure.
    * This failure can be returned by the YP library as of 4.1
    */
	else if (h_errno == TRY_AGAIN) 
	{
		sp->s_value.sv_host.h_exists = 1;

		sp->s_value.sv_host.h_down = 1;
		sp->s_value.sv_host.h_errno = ENAMESER;
	}
	clrevent(ev);
	return &sp->s_value.sv_host;		/* Return new entry */
}
/*
**  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 */
char	*NetName;			/* name of home (local?) network */

getrequests()
{
	int t;
	union wait status;
	struct sockaddr_in	addr;
	int on = 1;
	extern reapchild();

	/*
	**  Try to actually open the connection.
	*/
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_port = htons(IPPORT_SMTP);

	/* get a socket for the SMTP connection */
	DaemonSocket = socket(AF_INET, SOCK_STREAM, 0);
	if (DaemonSocket < 0)
	{
		/* probably another daemon already */
		syserr("getrequests: can't create socket");
	  severe:
# ifdef LOG
# ifdef LOG_SALERT
		if (LogLevel > 0)
			syslog(LOG_SALERT, "cannot get connection");
# else LOG_SALERT
		if (LogLevel > 0)
			syslog(LOG_CRIT|LOG_MAIL, "cannot get connection");
# endif LOG_SALERT
# endif LOG
		finis();
	}

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

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

	if (bind(DaemonSocket, &addr, sizeof addr) < 0)
	{
		syserr("getrequests: cannot bind");
		(void) close(DaemonSocket);
		goto severe;
	}
	if (listen(DaemonSocket, 5) < 0)
	{
		syserr("getrequests: cannot listen");
		(void) close(DaemonSocket);
		goto severe;
	}

	(void) signal(SIGCHLD, reapchild);

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

# ifdef LOG
	/* Tell the log that a new daemon has started. */
	syslog(LOG_INFO, "network daemon starting");
# endif LOG

	for (;;)
	{
		register int pid;
		auto int lotherend;
		struct sockaddr_in otherend;
		extern int RefuseLA;

		/* see if we are rejecting connections */
		while (RefuseLA > 0 && getla() > RefuseLA)
			sleep(5);

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

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

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

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

		if (pid == 0)
		{
			extern struct hostent *gethostbyaddr();
			register struct hostent *hp;
			char buf[MAXNAME];
			EVENT *ev;

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

			(void) signal(SIGCHLD, SIG_DFL);

			/* determine host name with timeout */
			if (setjmp(NameTimeout) != 0) {
			    hp = NULL;
			}
			else {
			    ev = setevent(nametime, nametimeout, 0);
			    hp = gethostbyaddr(
		&otherend.sin_addr, sizeof otherend.sin_addr, AF_INET);
			    clrevent(ev);
			}
			if (hp != NULL)
			{
				(void) strcpy(buf, hp->h_name);
				if (NetName != NULL && NetName[0] != '\0' &&
				    index(hp->h_name, '.') == NULL)
				{
					(void) strcat(buf, ".");
					(void) strcat(buf, NetName);
				}
			}
			else
			{
				extern char *inet_ntoa();

				/* produce a dotted quad */
				(void) sprintf(buf, "[%s]",
					inet_ntoa(otherend.sin_addr));
			}

			/* should we check for illegal connection here? XXX */

			RealHostName = newstr(buf);

			(void) close(DaemonSocket);
			setproctitle("From %s", (int)RealHostName);
			define('r', "TCP", CurEnv);
			InChannel = fdopen(t, "r");
			OutChannel = fdopen(t, "w");
# ifdef DEBUG
			if (tTd(15, 2))
				printf("getreq: returning\n");
# endif DEBUG
# ifdef LOG
			if (LogLevel > 11)
				syslog(LOG_DEBUG, "connected, pid=%d", getpid());
# endif LOG
			return;
		}

		/* close the port so that others will hang (for a while) */
		(void) close(t);

	}
	/*NOTREACHED*/
}
/*
**  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;
}
/*
**  MAKECONNECTION -- make a connection to an SMTP socket on another machine.
**
**	Parameters:
**		host -- the name of the host.