xref: /csrg-svn/usr.sbin/sendmail/src/daemon.c (revision 8352)

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

#ifndef DAEMON
SCCSID(@(#)daemon.c	3.30		10/07/82	(w/o daemon mode));
#else

# include <sys/socket.h>
# include <net/in.h>
# include <wait.h>

SCCSID(@(#)daemon.c	3.30		10/07/82	(with daemon mode));

/*
**  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.
**	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 describing the
**		error.
**
**	The semantics of both of these should be clean.
*/
/*
**  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.
*/

# define MAXCONNS	4	/* maximum simultaneous sendmails */

getrequests()
{
	union wait status;
	int numconnections = 0;

	for (;;)
	{
		register int pid;
		register int port;

		/*
		**  Wait for a connection.
		*/

		while ((port = getconnection()) < 0)
		{
			syserr("getrequests: getconnection failed");
			finis();
		}

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

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

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

		if (pid == 0)
		{
			/*
			**  CHILD -- return to caller.
			**	Verify calling user id if possible here.
			*/

			InChannel = fdopen(port, "r");
			OutChannel = fdopen(port, "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;
		}

		/*
		**  PARENT -- wait for child to terminate.
		**	Perhaps we should allow concurrent processing?
		*/

# ifdef DEBUG
		if (tTd(15, 2))
		{
			sleep(2);
			printf("getreq: parent waiting\n");
		}
# endif DEBUG

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

		/* pick up old zombies; implement load limiting */
		numconnections++;
		while (wait3(&status, numconnections < MAXCONNS ? WNOHANG : 0, 0) > 0)
			numconnections--;
	}
}
/*
**  GETCONNECTION -- make a connection with the outside world
**
**	Parameters:
**		none.
**
**	Returns:
**		The port for mail traffic.
**
**	Side Effects:
**		Waits for a connection.
*/

#define IPPORT_PLAYPORT	3055		/* random number */

struct sockaddr_in SendmailAddress = { AF_INET, IPPORT_SMTP };

getconnection()
{
	register int s;
	struct sockaddr otherend;

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

	SendmailAddress.sin_addr.s_addr = 0;
	SendmailAddress.sin_port = IPPORT_SMTP;
# ifdef DEBUG
	if (tTd(15, 15))
		SendmailAddress.sin_port = IPPORT_PLAYPORT;
# endif DEBUG
	SendmailAddress.sin_port = htons(SendmailAddress.sin_port);

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

# ifdef DEBUG
	if (tTd(15, 1))
		printf("getconnection\n");
# endif DEBUG

	for (;;)
	{
		int i;

		/* get a socket for the SMTP connection */
		/* do loop is to avoid 4.1b kernel bug (?) */
		i = 50;
		do
		{
			s = socket(SOCK_STREAM, 0, &SendmailAddress, SO_ACCEPTCONN);
			if (s < 0)
				sleep(5);
		} while (--i > 0 && s < 0);
		if (s < 0)
		{
			/* probably another daemon already */
			syserr("getconnection: can't create socket");
			return (-1);
		}

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

		/* wait for a connection */
		/* contorted code is due to a 4.1a kernel bug */
		errno = 0;
		if (accept(s, &otherend) >= 0)
			return (s);
		(void) close(s);
		if (errno != EINTR)
			syserr("getconnection: accept");
		sleep(5);
	}
}
/*
**  MAKECONNECTION -- make a connection to an SMTP socket on another machine.
**
**	Parameters:
**		host -- the name of the host.
**		port -- the port number to connect to.
**		outfile -- a pointer to a place to put the outfile
**			descriptor.
**		infile -- ditto for infile.
**
**	Returns:
**		An exit code telling whether the connection could be
**			made and if not why not.
**
**	Side Effects:
**		none.
*/

makeconnection(host, port, outfile, infile)
	char *host;
	u_short port;
	FILE **outfile;
	FILE **infile;
{
	register int s;

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

	if ((SendmailAddress.sin_addr.s_addr = rhost(&host)) == -1)
		return (EX_NOHOST);
	if (port == 0)
		port = IPPORT_SMTP;
	SendmailAddress.sin_port = htons(port);

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

# ifdef DEBUG
	if (tTd(16, 1))
		printf("makeconnection (%s)\n", host);
# endif DEBUG

	s = socket(SOCK_STREAM, 0, (struct sockaddr_in *) 0, 0);
	if (s < 0)
	{
		syserr("makeconnection: no socket");
		goto failure;
	}

# ifdef DEBUG
	if (tTd(16, 1))
		printf("makeconnection: %d\n", s);
# endif DEBUG
	(void) fflush(Xscript);				/* for debugging */
	if (connect(s, &SendmailAddress) < 0)
	{
		/* failure, decide if temporary or not */
	failure:
		switch (errno)
		{
		  case EISCONN:
		  case ETIMEDOUT:
		  case EINPROGRESS:
		  case EALREADY:
		  case EADDRINUSE:
		  case ENETDOWN:
		  case ENETRESET:
		  case ENOBUFS:
		  case ECONNREFUSED:
			/* there are others, I'm sure..... */
			return (EX_TEMPFAIL);

		  default:
			return (EX_UNAVAILABLE);
		}
	}

	/* connection ok, put it into canonical form */
	*outfile = fdopen(s, "w");
	*infile = fdopen(s, "r");

	return (0);
}

#endif DAEMON