/* $Header: /home/aggarwal/lsrc/nocol/src/lib/RCS/eventlog.c,v 3.4 1993/11/03 20:51:03 aggarwal Exp $ */

/*
 * DESCRIPTION
 *	A small library of functions for use in connecting to the
 *	NOCOL event logging daemon  (noclogd).
 *
 * Caveats:
 *
 *	The server host is hardcoded  (NLOG_HOST)
 */

/*
 * AUTHOR
 *	David Wagner, wagner@jvnc.net
 *
 *	Modified by:  vikas@jvnc.net
 */

/*+
 * $Log: eventlog.c,v $
 * Revision 3.4  1993/11/03  20:51:03  aggarwal
 * Added ifdef for h_addr (defined in netdb.h) in case its defined.
 *
 * Revision 3.3  1993/11/02  21:20:15  aggarwal
 * Did not need the htons in front of the sp->s_port on line 134
 *
 * Revision 3.2  1993/10/30  03:23:17  aggarwal
 * Fixed the ntohs and htons mixup
 *
 * Revision 3.1  1993/10/11  20:49:19  aggarwal
 * Fixed bug in converting gethostname() output to inaddr.
 * Also reduced the delaycount to 50 instead of 100 and sleep(1).
 *
 * Revision 3.0  1993/09/21  20:20:08  aggarwal
 * Deleted the Unix socket feature entirely. Tested, and seems ready
 * to go.
 *
 * Revision 2.0  1993/09/18  21:52:18  aggarwal
 * This version 2.0 tries to use stream Unix sockets and dgram inet
 * sockets. This is not workable, see comments in noclogd.c for more
 * details.
 *
 * This file is checked in just to record the way something like this
 * 'could' be done.
 *
 * Revision 1.4  1993/09/14  21:45:59  aggarwal
 * Put detailed fail message between ifdef DEBUG since we normally
 * don't want to see this message.
 *
 * Revision 1.3  1993/09/14  15:34:45  aggarwal
 * Does a sizeof(v) instead of sizeof(EVENT)
 *
 * Revision 1.2  1993/09/14  12:59:36  aggarwal
 * Cleaned up and made more robust.
 *
 * Revision 1.1  1993/09/13  13:31:22  aggarwal
 * Initial revision
 *
 */

#ifndef lint
 static char rcsid[] = "$Id: eventlog.c,v 3.4 1993/11/03 20:51:03 aggarwal Exp $" ;
#endif

#include "noclogd.h"
#include <sys/time.h>

/*
 * The logfile descriptor:   -2 if it hasn't been opened at all, and
 * 	-1 if openeventlog()  failed.
 */
static int logfd= -2;		/* global in this module */
static int delaycount;		/* to prevent overrunning the dgram server */
static time_t	closetime;

/*
 * Opens a socket to the nocol logging daemon.
 * Returns 0 on success, or prints an error message to stderr
 * and returns -1 on failure. ON failure, it MUST change logfd
 * to a value of -1.
 */
int openeventlog()
{
    struct sockaddr_in	sin;
    struct servent	*sp;
    char *s ;

    /* Silently fail if there's already a connection open */
    if (logfd >= 0)
      return(-1);

    /*
     * Try to open a connection to the log address over the network.
     */

    logfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (logfd < 0) {
	perror("openeventlog: AF_INET socket() failed");
	logfd = -1 ;
	return(-1);
    }
    
    /* Got a socket, now assign family, server_addr, dest port */
    bzero(&sin, sizeof(sin));

    sin.sin_family = AF_INET;
    s = NLOG_HOST ;
    if (isdigit(*s))		/* given an address, not a name */
      sin.sin_addr.s_addr = inet_addr(s);
    else
    {
	struct hostent  *hp ;	/* gethostbyname returns in_addr structures */
	if ((hp = gethostbyname(NLOG_HOST)) == NULL)
	{
	    perror("openeventlog");
	    fprintf(stderr, "gethostbyname() failed for %s\n", NLOG_HOST);
	    logfd = -1 ;
	    return(-1);
	}
#ifdef h_addr		/* in netdb.h */
	bcopy((char *)hp->h_addr, (char *)&sin.sin_addr,hp->h_length);
#else
	bcopy((char *)hp->h_addr_list[0], (char *)&sin.sin_addr,hp->h_length);
#endif
    }


#ifdef DEBUG
    fprintf(stderr, "openeventlog: logging to %s\n", inet_ntoa(sin.sin_addr)) ;
#endif

    if (sin.sin_addr.s_addr == -1)	/* error */
    {
	perror("openeventlog: inet_addr() failed");
	logfd = -1 ;
	return(-1);
    }	

    /* Figure out what port number to use */
    if ((sp = getservbyname(NLOG_SERVICE, "udp")) == NULL)
      sin.sin_port = htons(NLOG_PORT);
    else
      sin.sin_port = sp->s_port;
    
    if (connect(logfd, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
        perror("client: AF_INET connect() failed");
	logfd = -1;
	return(-1);
    }

#ifdef DEBUG
    fprintf(stderr, "openeventlog: opened INET socket %d\n", logfd);
#endif
    
    return(0);
}

/*
 * Writes an EVENT structure to the nocol logging daemon.
 * The connection must have been already created with openeventlog().
 * If logfd = -2, then assumes that the user erred and never called
 * openeventlog(), so it does it for him.
 * Returns 0 on success, or prints an error message to stderr
 * and returns -1  on failure.
 *
 * NOTE: since the socket is of the connectionless type, logfd might actually
 *	be okay, but the logging daemon might not be up. There is no
 *	way to tell since a connection is not established with the logging
 *	daemon.
 */
#define RETRY_REOPEN	1*60	/* seconds before trying to reopen logfd */

int eventlog(v)
     EVENT *v;
{
    int bytesleft, retval;

    if (logfd == -2)	/* Never been tried, try to open if RETRY_REOPEN */
    {
	time_t curtime = time((time_t *) NULL);

	if ((curtime - closetime) > RETRY_REOPEN)
	  openeventlog();
    }

    if (logfd < 0)    	/* Silently fail if no connection could be opened */
      return(-1);
    
    for (bytesleft=sizeof(*v); bytesleft > 0; bytesleft-=retval)
      if ((retval=write(logfd, (char *)v, bytesleft)) < 0)
      {
#ifdef DEBUG
	  perror("eventlog: write() failed");
#endif /* DEBUG */
	  closeeventlog();	/* no point keeping it open */
	  return(-1);
      }

    if ((++delaycount % 50) == 0)	/* small delay after X loggings */
    {
      delaycount = 0 ;
      sleep(1);
    }

    return(0);
}

/*
 * Closes the current connection to the nocol logging daemon.
 */
int closeeventlog()
{
    /* Silently fail if no connection has been opened yet */
    if (logfd < 0)
      return(-1);
    
    if (close(logfd) < 0) {
	perror("closeeventlog: close() failed");
	return(-1);
    }

    /*
     * Reset things cleanly so we can call openeventlog() later if we want.
     * Store the time that we closed the file desc so that we don't try
     * and reopen too many times in 'openeventlog'
     */
    closetime = time((time_t *) NULL);

    logfd = -2;
    return(0);
}