default_v0_fn.c

/*
   Copyright (c) 1995-1998 by Cisco systems, Inc.

   Permission to use, copy, modify, and distribute this software for
   any purpose and without fee is hereby granted, provided that this
   copyright and permission notice appear on all copies of the
   software and supporting documentation, the name of Cisco Systems,
   Inc. not be used in advertising or publicity pertaining to
   distribution of the program without specific prior permission, and
   notice be given in supporting documentation that modification,
   copying and distribution is by permission of Cisco Systems, Inc.

   Cisco Systems, Inc. makes no representations about the suitability
   of this software for any purpose.  THIS SOFTWARE IS PROVIDED ``AS
   IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
   WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS FOR A PARTICULAR PURPOSE.
*/

#include "tac_plus.h"
#include "expire.h"

/* internal state variables */
#define STATE_AUTHEN_START   0	/* no requests issued */
#define STATE_AUTHEN_GETUSER 1	/* username has been requested */
#define STATE_AUTHEN_GETPASS 2	/* password has been requested */

struct private_data {
    char password[MAX_PASSWD_LEN + 1];
    int state;
};

/*
 * Default tacacs login authentication function. Wants a username
 * and a password, and tries to verify them.
 *
 * Choose_authen will ensure that we already have a username before this
 * gets called.
 *
 * We will query for a password and keep it in the method_data.
 *
 * Any strings returned via pointers in authen_data must come from the
 * heap. They will get freed by the caller.
 *
 * Return 0 if data->status is valid, otherwise 1
 */

int
default_v0_fn(data)
struct authen_data *data;
{
    char *name, *passwd;
    struct private_data *p;
    char *prompt;

    p = (struct private_data *) data->method_data;

    /* An abort has been received. Clean up and return */
    if (data->flags & TAC_PLUS_CONTINUE_FLAG_ABORT) {
	if (data->method_data)
	    free(data->method_data);
	data->method_data = NULL;
	return (1);
    }
    /* Initialise method_data if first time through */
    if (!p) {
	p = (struct private_data *) tac_malloc(sizeof(struct private_data));
	bzero(p, sizeof(struct private_data));
	data->method_data = p;
	p->state = STATE_AUTHEN_START;
    }

    /* Unless we're enabling, we need a username */
    if (data->service != TAC_PLUS_AUTHEN_SVC_ENABLE &&
	!(char) data->NAS_id->username[0]) {
	switch (p->state) {

	case STATE_AUTHEN_GETUSER:
	    /* we have previously asked for a username but none came back.
	     * This is a gross error */
	    data->status = TAC_PLUS_AUTHEN_STATUS_ERROR;
	    report(LOG_ERR, "%s: No username supplied after GETUSER",
		   session.peer);
	    return (0);

	case STATE_AUTHEN_START:
	    /* No username. Try requesting one */
	    data->status = TAC_PLUS_AUTHEN_STATUS_GETUSER;
	    if (data->service == TAC_PLUS_AUTHEN_SVC_LOGIN) {
		if ( !(prompt=(char *)cfg_get_host_prompt(data->NAS_id->NAS_name)) )
		prompt = "\nUser Access Verification\n\nUsername: ";
	    } else {
		prompt = "Username: ";
	    }
	    data->server_msg = tac_strdup(prompt);
	    p->state = STATE_AUTHEN_GETUSER;
	    return (0);

	default:
	    /* something awful has happened. Give up and die */
	    report(LOG_ERR, "%s: default_fn bad state %d", 
		   session.peer, p->state);
	    return (1);
	}
    }

    /* we now have a username if we needed one */
    name = data->NAS_id->username;

    /* Do we have a password? */
    passwd = p->password;

    if (!passwd[0]) {

	/* no password yet. Either we need to ask for one and expect to get
	 * called again, or we asked but nothing came back, which is fatal */

	switch (p->state) {
	case STATE_AUTHEN_GETPASS:
	    /* We already asked for a password. This should be the reply */
	    strncpy(passwd, data->client_msg, MAX_PASSWD_LEN);
	    passwd[MAX_PASSWD_LEN + 1] = '\0';
	    break;

	default:
	    data->flags = TAC_PLUS_AUTHEN_FLAG_NOECHO;
	    data->server_msg = tac_strdup("Password: ");
	    data->status = TAC_PLUS_AUTHEN_STATUS_GETPASS;
	    p->state = STATE_AUTHEN_GETPASS;
	    return (0);
	}
    }

    /* We have a username and password. Try validating */

    if (STREQ(name, DEFAULT_USERNAME)) {
	/* Never authenticate this user. It's for authorization only */
	data->status = TAC_PLUS_AUTHEN_STATUS_FAIL;
	if (debug) {
	    report(LOG_DEBUG, 
		   "authentication query for '%s' %s from %s rejected",
		   name && name[0] ? name : "unknown",
		   session.port, session.peer);
	}
	return(0);
    }

    /* Assume the worst */
    data->status = TAC_PLUS_AUTHEN_STATUS_FAIL;

    switch (data->service) {
    case TAC_PLUS_AUTHEN_SVC_NASI:
    case TAC_PLUS_AUTHEN_SVC_LOGIN:
    case TAC_PLUS_AUTHEN_SVC_PPP:
	verify(name, passwd, data, TAC_PLUS_RECURSE);
	if (debug)
	    report(LOG_INFO, "login query for '%s' %s from %s %s",
		   name && name[0] ? name : "unknown",
		   data->NAS_id->NAS_port && data->NAS_id->NAS_port[0] ?
		       data->NAS_id->NAS_port : "unknown",
		   session.peer,
		   (data->status == TAC_PLUS_AUTHEN_STATUS_PASS) ?
		   "accepted" : "rejected");
	break;

    default:
	data->status = TAC_PLUS_AUTHEN_STATUS_ERROR;
	report(LOG_ERR, "%s: Bogus service value %d from packet", 
	       session.peer, data->service);
	break;
    }

    if (data->method_data)
	free(data->method_data);
    data->method_data = NULL;

    switch (data->status) {
    case TAC_PLUS_AUTHEN_STATUS_ERROR:
    case TAC_PLUS_AUTHEN_STATUS_FAIL:
    case TAC_PLUS_AUTHEN_STATUS_PASS:
	return (0);
    default:
	report(LOG_ERR, "%s: default_v0_fn can't set status %d",
	       session.peer, data->status);
	data->status = TAC_PLUS_AUTHEN_STATUS_ERROR;
	return (1);
    }
}