/*
 *
 *	Copyright (C) 1988, 1989 by the Massachusetts Institute of Technology
 *    	Developed by the MIT Student Information Processing Board (SIPB).
 *    	For copying information, see the file mit-copyright.h in this release.
 *
 */
/*
 *
 *	$Source: /mit/discuss/source/libds/RCS/auth_krb.c,v $
 *	$Header: /mit/discuss/source/libds/RCS/auth_krb.c,v 1.8 91/08/07 14:14:50 tytso Exp $
 *
 * auth_krb () -- Authentication procedure for kerberos.  This contains the
 *		  standard authentication for kerberos.
 *
 */
#ifndef lint
static char *rcsid_auth_krb_c =
    "$Header: /mit/discuss/source/libds/RCS/auth_krb.c,v 1.8 91/08/07 14:14:50 tytso Exp $";
#endif lint

#include <strings.h>
#include <ctype.h>
#include "krb.h"
#include "krb_err.h"

char *index (), *local_host_name ();

#define NULL 0

/*
 *
 * get_authenticator () -- Interface routine to get an authenticator over
 *			   the net.  Input is a service name (for kerberos,
 *			   this is in the form of service@REALM), optional
 *			   checksum.  We return a pointer to the authenticator,
 *			   its length, and a standard error code.
 *
 */
get_authenticator (service_id, checksum, authp, authl, result)
char *service_id;
int checksum;
char **authp;
int *authl;
int *result;
{
     char *realmp,*instancep;
     char serv [SNAME_SZ+INST_SZ];
     int rem;

     static KTEXT_ST ticket;

     init_krb_err_tbl();

     realmp = index (service_id, '@');
     if (realmp == NULL || realmp - service_id >= sizeof (serv)) {
	  realmp = "";
	  strncpy (serv, service_id, sizeof (serv));
     } else {
	 bcopy (service_id, serv, realmp - service_id); /* copy over to serv */
	 serv [realmp - service_id] = '\0';
	 realmp++;
     }

     /* look for service instance */
     instancep = index (serv, '.');
     if (instancep == NULL) {
	  instancep = "";
     } else {
	  *instancep++ = '\0';
     }

     rem = krb_mk_req (&ticket, serv, instancep, realmp, checksum);
     if (rem == KSUCCESS) {
	  *authl = ticket.length;
	  *authp = (char *) ticket.dat;
	  *result = 0;
     } else {
	  *authl = 0;
	  *authp = NULL;
	  *result = rem + krb_err_base;
     }
}