/*
 *	IvyDaemon, an Ivy gateway for short-lived agents
 * 
 *	Copyright (C) 1999
 *	Centre d'Études de la Navigation Aérienne
 *
 *	Main file for the super-daemon
 *
 *	Author(s): Stephane Chatty <chatty@cenatoulouse.dgac.fr>
 *		from code by Patrick Amar <pa@lri.fr>
 *
 *	$Id$
 *
 *	Please refer to file version.h for the
 *	copyright notice regarding this software
 *
 */

/*
 * The super-demon (in.ivyd):
 *
 *     It is either launched by inetd with the socket SOCK_DGRAM on file descriptor 0,
 *     or at boot time with the -boot flag.
 *
 * The daemon (ivyd):
 *	
 *     It sends the super-daemon a message connmsg of type MSG_SERVER that contains
 *     the port number of the socket it connected to.
 *
 * The clients (ivyecho, ...):
 *
 *     They send the super-daemon a message connmsg of type MSG_CLIENT 
 *     to ask for the port number
 *
 * L'identification de l'emetteur du paquet est le numero d'utilisateur.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <memory.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/signal.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <netdb.h>
#include <errno.h>

#include "ivyd.h"


const char* const dumpfilename = "/tmp/in.ivyd.db";
const int dumpfilemode = 0644;
const char* const servicename = "ivyd";
const char* const port_env_variable = "INIVYD_PORT";
const int default_port = 3006;

/*
 * The association table managed by the super-daemon
 */

typedef struct {
	short	s_port;	/* port number */
	short	s_key;	/* server id */
} serverinfo;

#define TABSIZ 64	/* 64 simultaneous servers are allowed */
serverinfo	si_table [TABSIZ];

serverinfo*
GetInfo (int key)
{
	register serverinfo *si;
	register serverinfo *res = 0;

	for (si = si_table; si - si_table < TABSIZ; ++si) {
		if (si->s_port == 0) {
			if (! res)
				res = si;
			continue;
		}
		if (si->s_key != key)
			continue;
		res = si;
		break;
	}
	return res;
}

/*
 * DumpInfo ()
 *
 * Dumps to a file the contents of the table
 */

int
DumpInfo ()
{
	register serverinfo *si;
	register int fd = creat (dumpfilename, dumpfilemode);
	char buf [512];

	if (fd == -1)
		return 0;

	for (si = si_table; si - si_table < TABSIZ; ++si) {
		if (! si->s_port)
			continue;
		(void) sprintf (buf, "user %5d, port %d\n", si->s_key, ntohs (si->s_port));
		(void) write (fd, buf, strlen (buf));
	}
	(void) close (fd);
	return 1;
}


void
SigHup (int sig)
{
	DumpInfo ();
}

void
main (int argc, const char **argv)
{
	struct servent *serv;
	u_short serv_port = 0;
	struct sockaddr_in from;
	int fromlen;
	struct connmsg msg;
	register serverinfo *si;
	int boot = 0;
	int debug = 0;

	(void) signal (SIGHUP, SigHup);
	
	serv = getservbyname (servicename, 0);

 	if (! serv) {
		char *pp = getenv (port_env_variable);
		serv_port = htons (pp ? atoi (pp) : default_port);
		if (serv_port <= 0)
			exit (0);
	} else
		serv_port = serv -> s_port;
	
	++argv;
	while (argc > 1) {
		if (strcmp (*argv, "-boot") == 0 || strcmp (*argv, "-b") == 0)
			boot = 1;
		else if (strcmp (*argv, "-debug") == 0 || strcmp (*argv, "-d") == 0)
			debug = 1;
		else
			fprintf (stderr, "bad option %s\n", *argv);
		++argv;
		--argc;
	}

	/* special case when launched at boot time (ie. not from inetd) */

	if (boot) {
		/* in normal mode, we behave as a daemon with no terminal */
		if (!debug) {
			int s;

			/* first let's fork... */
			if (fork ())
				exit (0);
	
			/* ...then let's close all descriptors... */
			for (s = getdtablesize (); --s >= 0;)
				close (s);

			/* ... and get rid of our control terminal */
			if (-1 != open ("/dev/tty", 2)) {
				(void) ioctl (0, TIOCNOTTY, 0);
				close (0);
			}
		} else
			close (0);

		/* Now it's time to open the socket for requests */
		if (-1 == socket (AF_INET, SOCK_DGRAM, 0))
			exit (1);
		memset (&from, 0, sizeof from);
		from.sin_family = AF_INET;
		from.sin_port = serv_port;
		from.sin_addr.s_addr = INADDR_ANY;
		if (-1 == bind (0, &from, sizeof from))
			exit (1);
	}		

	/* now we can handle messages and requests */
	for (;;) {
		fromlen = sizeof from;
		if (recvfrom (0, (char *)&msg, sizeof msg, 0, (struct sockaddr *)&from, &fromlen) <= 0) {
			if (errno == EINTR)
				continue;
			exit (1);
		}

		si = GetInfo (msg.msg_key);
		switch (msg.msg_type) {

		/* message from server: we store the information */
		case MSG_SERVER:
			si->s_port = msg.msg_port;
			si->s_key  = msg.msg_key;
			break;

		/* message from a client: we retrieve and send the information */
		case MSG_CLIENT:
			msg.msg_port = si->s_port;
			msg.msg_type = MSG_REPLY;
			(void) sendto (0, (char *)&msg, sizeof msg, 0, (struct sockaddr *)&from, fromlen);
			break;
		}

	}
}