/*
 * Copyright (c) 1997 - 2007 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include <krb5_locl.h>

RCSID("$Id: rd_req.c 22235 2007-12-08 21:52:07Z lha $");

static krb5_error_code
decrypt_tkt_enc_part (krb5_context context,
		      krb5_keyblock *key,
		      EncryptedData *enc_part,
		      EncTicketPart *decr_part)
{
    krb5_error_code ret;
    krb5_data plain;
    size_t len;
    krb5_crypto crypto;

    ret = krb5_crypto_init(context, key, 0, &crypto);
    if (ret)
	return ret;
    ret = krb5_decrypt_EncryptedData (context,
				      crypto,
				      KRB5_KU_TICKET,
				      enc_part,
				      &plain);
    krb5_crypto_destroy(context, crypto);
    if (ret)
	return ret;

    ret = krb5_decode_EncTicketPart(context, plain.data, plain.length, 
				    decr_part, &len);
    krb5_data_free (&plain);
    return ret;
}

static krb5_error_code
decrypt_authenticator (krb5_context context,
		       EncryptionKey *key,
		       EncryptedData *enc_part,
		       Authenticator *authenticator,
		       krb5_key_usage usage)
{
    krb5_error_code ret;
    krb5_data plain;
    size_t len;
    krb5_crypto crypto;

    ret = krb5_crypto_init(context, key, 0, &crypto);
    if (ret)
	return ret;
    ret = krb5_decrypt_EncryptedData (context,
				      crypto,
				      usage /* KRB5_KU_AP_REQ_AUTH */,
				      enc_part,
				      &plain);
    /* for backwards compatibility, also try the old usage */
    if (ret && usage == KRB5_KU_TGS_REQ_AUTH)
	ret = krb5_decrypt_EncryptedData (context,
					  crypto,
					  KRB5_KU_AP_REQ_AUTH,
					  enc_part,
					  &plain);
    krb5_crypto_destroy(context, crypto);
    if (ret)
	return ret;

    ret = krb5_decode_Authenticator(context, plain.data, plain.length, 
				    authenticator, &len);
    krb5_data_free (&plain);
    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_decode_ap_req(krb5_context context,
		   const krb5_data *inbuf,
		   krb5_ap_req *ap_req)
{
    krb5_error_code ret;
    size_t len;
    ret = decode_AP_REQ(inbuf->data, inbuf->length, ap_req, &len);
    if (ret)
	return ret;
    if (ap_req->pvno != 5){
	free_AP_REQ(ap_req);
	krb5_clear_error_string (context);
	return KRB5KRB_AP_ERR_BADVERSION;
    }
    if (ap_req->msg_type != krb_ap_req){
	free_AP_REQ(ap_req);
	krb5_clear_error_string (context);
	return KRB5KRB_AP_ERR_MSG_TYPE;
    }
    if (ap_req->ticket.tkt_vno != 5){
	free_AP_REQ(ap_req);
	krb5_clear_error_string (context);
	return KRB5KRB_AP_ERR_BADVERSION;
    }
    return 0;
}

static krb5_error_code
check_transited(krb5_context context, Ticket *ticket, EncTicketPart *enc)
{
    char **realms;
    int num_realms;
    krb5_error_code ret;
	    
    /* 
     * Windows 2000 and 2003 uses this inside their TGT so it's normaly
     * not seen by others, however, samba4 joined with a Windows AD as
     * a Domain Controller gets exposed to this.
     */
    if(enc->transited.tr_type == 0 && enc->transited.contents.length == 0)
	return 0;

    if(enc->transited.tr_type != DOMAIN_X500_COMPRESS)
	return KRB5KDC_ERR_TRTYPE_NOSUPP;

    if(enc->transited.contents.length == 0)
	return 0;

    ret = krb5_domain_x500_decode(context, enc->transited.contents, 
				  &realms, &num_realms, 
				  enc->crealm,
				  ticket->realm);
    if(ret)
	return ret;
    ret = krb5_check_transited(context, enc->crealm, 
			       ticket->realm, 
			       realms, num_realms, NULL);
    free(realms);
    return ret;
}

static krb5_error_code
find_etypelist(krb5_context context,
	       krb5_auth_context auth_context,
	       EtypeList *etypes)
{
    krb5_error_code ret;
    krb5_authdata *ad;
    krb5_authdata adIfRelevant;
    unsigned i;

    adIfRelevant.len = 0;

    etypes->len = 0;
    etypes->val = NULL;

    ad = auth_context->authenticator->authorization_data;
    if (ad == NULL)
	return 0;

    for (i = 0; i < ad->len; i++) {
	if (ad->val[i].ad_type == KRB5_AUTHDATA_IF_RELEVANT) {
	    ret = decode_AD_IF_RELEVANT(ad->val[i].ad_data.data,
					ad->val[i].ad_data.length,
					&adIfRelevant,
					NULL);
	    if (ret)
		return ret;

	    if (adIfRelevant.len == 1 &&
		adIfRelevant.val[0].ad_type ==
			KRB5_AUTHDATA_GSS_API_ETYPE_NEGOTIATION) {
		break;
	    }
	    free_AD_IF_RELEVANT(&adIfRelevant);
	    adIfRelevant.len = 0;
	}
    }

    if (adIfRelevant.len == 0)
	return 0;

    ret = decode_EtypeList(adIfRelevant.val[0].ad_data.data,
			   adIfRelevant.val[0].ad_data.length,
			   etypes,
			   NULL);
    if (ret)
	krb5_clear_error_string(context);

    free_AD_IF_RELEVANT(&adIfRelevant);

    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_decrypt_ticket(krb5_context context,
		    Ticket *ticket,
		    krb5_keyblock *key,
		    EncTicketPart *out,
		    krb5_flags flags)
{
    EncTicketPart t;
    krb5_error_code ret;
    ret = decrypt_tkt_enc_part (context, key, &ticket->enc_part, &t);
    if (ret)
	return ret;
    
    {
	krb5_timestamp now;
	time_t start = t.authtime;

	krb5_timeofday (context, &now);
	if(t.starttime)
	    start = *t.starttime;
	if(start - now > context->max_skew
	   || (t.flags.invalid
	       && !(flags & KRB5_VERIFY_AP_REQ_IGNORE_INVALID))) {
	    free_EncTicketPart(&t);
	    krb5_clear_error_string (context);
	    return KRB5KRB_AP_ERR_TKT_NYV;
	}
	if(now - t.endtime > context->max_skew) {
	    free_EncTicketPart(&t);
	    krb5_clear_error_string (context);
	    return KRB5KRB_AP_ERR_TKT_EXPIRED;
	}
	
	if(!t.flags.transited_policy_checked) {
	    ret = check_transited(context, ticket, &t);
	    if(ret) {
		free_EncTicketPart(&t);
		return ret;
	    }
	}
    }
    
    if(out)
	*out = t;
    else
	free_EncTicketPart(&t);
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_verify_authenticator_checksum(krb5_context context,
				   krb5_auth_context ac,
				   void *data,
				   size_t len)
{
    krb5_error_code ret;
    krb5_keyblock *key;
    krb5_authenticator authenticator;
    krb5_crypto crypto;
    
    ret = krb5_auth_con_getauthenticator (context,
				      ac,
				      &authenticator);
    if(ret)
	return ret;
    if(authenticator->cksum == NULL) {
	krb5_free_authenticator(context, &authenticator);
	return -17;
    }
    ret = krb5_auth_con_getkey(context, ac, &key);
    if(ret) {
	krb5_free_authenticator(context, &authenticator);
	return ret;
    }
    ret = krb5_crypto_init(context, key, 0, &crypto);
    if(ret)
	goto out;
    ret = krb5_verify_checksum (context,
				crypto,
				KRB5_KU_AP_REQ_AUTH_CKSUM,
				data,
				len,
				authenticator->cksum);
    krb5_crypto_destroy(context, crypto);
out:
    krb5_free_authenticator(context, &authenticator);
    krb5_free_keyblock(context, key);
    return ret;
}


krb5_error_code KRB5_LIB_FUNCTION
krb5_verify_ap_req(krb5_context context,
		   krb5_auth_context *auth_context,
		   krb5_ap_req *ap_req,
		   krb5_const_principal server,
		   krb5_keyblock *keyblock,
		   krb5_flags flags,
		   krb5_flags *ap_req_options,
		   krb5_ticket **ticket)
{
    return krb5_verify_ap_req2 (context,
				auth_context,
				ap_req,
				server,
				keyblock,
				flags,
				ap_req_options,
				ticket,
				KRB5_KU_AP_REQ_AUTH);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_verify_ap_req2(krb5_context context,
		    krb5_auth_context *auth_context,
		    krb5_ap_req *ap_req,
		    krb5_const_principal server,
		    krb5_keyblock *keyblock,
		    krb5_flags flags,
		    krb5_flags *ap_req_options,
		    krb5_ticket **ticket,
		    krb5_key_usage usage)
{
    krb5_ticket *t;
    krb5_auth_context ac;
    krb5_error_code ret;
    EtypeList etypes;
    
    if (ticket)
	*ticket = NULL;

    if (auth_context && *auth_context) {
	ac = *auth_context;
    } else {
	ret = krb5_auth_con_init (context, &ac);
	if (ret)
	    return ret;
    }

    t = calloc(1, sizeof(*t));
    if (t == NULL) {
	ret = ENOMEM;
	krb5_clear_error_string (context);
	goto out;
    }

    if (ap_req->ap_options.use_session_key && ac->keyblock){
	ret = krb5_decrypt_ticket(context, &ap_req->ticket, 
				  ac->keyblock, 
				  &t->ticket,
				  flags);
	krb5_free_keyblock(context, ac->keyblock);
	ac->keyblock = NULL;
    }else
	ret = krb5_decrypt_ticket(context, &ap_req->ticket, 
				  keyblock, 
				  &t->ticket,
				  flags);
    
    if(ret)
	goto out;

    ret = _krb5_principalname2krb5_principal(context,
					     &t->server,
					     ap_req->ticket.sname, 
					     ap_req->ticket.realm);
    if (ret) goto out;
    ret = _krb5_principalname2krb5_principal(context,
					     &t->client,
					     t->ticket.cname, 
					     t->ticket.crealm);
    if (ret) goto out;

    /* save key */

    ret = krb5_copy_keyblock(context, &t->ticket.key, &ac->keyblock);
    if (ret) goto out;

    ret = decrypt_authenticator (context,
				 &t->ticket.key,
				 &ap_req->authenticator,
				 ac->authenticator,
				 usage);
    if (ret)
	goto out;

    {
	krb5_principal p1, p2;
	krb5_boolean res;
	
	_krb5_principalname2krb5_principal(context,
					   &p1,
					   ac->authenticator->cname,
					   ac->authenticator->crealm);
	_krb5_principalname2krb5_principal(context,
					   &p2, 
					   t->ticket.cname,
					   t->ticket.crealm);
	res = krb5_principal_compare (context, p1, p2);
	krb5_free_principal (context, p1);
	krb5_free_principal (context, p2);
	if (!res) {
	    ret = KRB5KRB_AP_ERR_BADMATCH;
	    krb5_clear_error_string (context);
	    goto out;
	}
    }

    /* check addresses */

    if (t->ticket.caddr
	&& ac->remote_address
	&& !krb5_address_search (context,
				 ac->remote_address,
				 t->ticket.caddr)) {
	ret = KRB5KRB_AP_ERR_BADADDR;
	krb5_clear_error_string (context);
	goto out;
    }

    /* check timestamp in authenticator */
    {
	krb5_timestamp now;

	krb5_timeofday (context, &now);

	if (abs(ac->authenticator->ctime - now) > context->max_skew) {
	    ret = KRB5KRB_AP_ERR_SKEW;
	    krb5_clear_error_string (context);
	    goto out;
	}
    }

    if (ac->authenticator->seq_number)
	krb5_auth_con_setremoteseqnumber(context, ac,
					 *ac->authenticator->seq_number);

    /* XXX - Xor sequence numbers */

    if (ac->authenticator->subkey) {
	ret = krb5_auth_con_setremotesubkey(context, ac,
					    ac->authenticator->subkey);
	if (ret)
	    goto out;
    }

    ret = find_etypelist(context, ac, &etypes);
    if (ret)
	goto out;

    ac->keytype = ETYPE_NULL;

    if (etypes.val) {
	int i;

	for (i = 0; i < etypes.len; i++) {
	    if (krb5_enctype_valid(context, etypes.val[i]) == 0) {
		ac->keytype = etypes.val[i];
		break;
	    }
	}
    }

    if (ap_req_options) {
	*ap_req_options = 0;
	if (ac->keytype != ETYPE_NULL)
	    *ap_req_options |= AP_OPTS_USE_SUBKEY;
	if (ap_req->ap_options.use_session_key)
	    *ap_req_options |= AP_OPTS_USE_SESSION_KEY;
	if (ap_req->ap_options.mutual_required)
	    *ap_req_options |= AP_OPTS_MUTUAL_REQUIRED;
    }

    if(ticket)
	*ticket = t;
    else
	krb5_free_ticket (context, t);
    if (auth_context) {
	if (*auth_context == NULL)
	    *auth_context = ac;
    } else
	krb5_auth_con_free (context, ac);
    free_EtypeList(&etypes);
    return 0;
 out:
    if (t)
	krb5_free_ticket (context, t);
    if (auth_context == NULL || *auth_context == NULL)
	krb5_auth_con_free (context, ac);
    return ret;
}
		   
/*
 *
 */

struct krb5_rd_req_in_ctx_data {
    krb5_keytab keytab;
    krb5_keyblock *keyblock;
    krb5_boolean check_pac;
};

struct krb5_rd_req_out_ctx_data {
    krb5_keyblock *keyblock;
    krb5_flags ap_req_options;
    krb5_ticket *ticket;
};

/*
 *
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_in_ctx_alloc(krb5_context context, krb5_rd_req_in_ctx *ctx)
{
    *ctx = calloc(1, sizeof(**ctx));
    if (*ctx == NULL) {
	krb5_set_error_string(context, "out of memory");
	return ENOMEM;
    }
    (*ctx)->check_pac = (context->flags & KRB5_CTX_F_CHECK_PAC) ? 1 : 0;
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_in_set_keytab(krb5_context context, 
			  krb5_rd_req_in_ctx in,
			  krb5_keytab keytab)
{
    in->keytab = keytab; /* XXX should make copy */
    return 0;
}

/**
 * Set if krb5_rq_red() is going to check the Windows PAC or not
 * 
 * @param context Keberos 5 context.
 * @param in krb5_rd_req_in_ctx to check the option on.
 * @param flag flag to select if to check the pac (TRUE) or not (FALSE).
 *
 * @return Kerberos 5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_in_set_pac_check(krb5_context context, 
			     krb5_rd_req_in_ctx in,
			     krb5_boolean flag)
{
    in->check_pac = flag;
    return 0;
}


krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_in_set_keyblock(krb5_context context, 
			    krb5_rd_req_in_ctx in,
			    krb5_keyblock *keyblock)
{
    in->keyblock = keyblock; /* XXX should make copy */
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_out_get_ap_req_options(krb5_context context, 
				   krb5_rd_req_out_ctx out,
				   krb5_flags *ap_req_options)
{
    *ap_req_options = out->ap_req_options;
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_out_get_ticket(krb5_context context, 
			    krb5_rd_req_out_ctx out,
			    krb5_ticket **ticket)
{
    return krb5_copy_ticket(context, out->ticket, ticket);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_out_get_keyblock(krb5_context context, 
			    krb5_rd_req_out_ctx out,
			    krb5_keyblock **keyblock)
{
    return krb5_copy_keyblock(context, out->keyblock, keyblock);
}

void  KRB5_LIB_FUNCTION
krb5_rd_req_in_ctx_free(krb5_context context, krb5_rd_req_in_ctx ctx)
{
    free(ctx);
}

krb5_error_code KRB5_LIB_FUNCTION
_krb5_rd_req_out_ctx_alloc(krb5_context context, krb5_rd_req_out_ctx *ctx)
{
    *ctx = calloc(1, sizeof(**ctx));
    if (*ctx == NULL) {
	krb5_set_error_string(context, "out of memory");
	return ENOMEM;
    }
    return 0;
}

void  KRB5_LIB_FUNCTION
krb5_rd_req_out_ctx_free(krb5_context context, krb5_rd_req_out_ctx ctx)
{
    krb5_free_keyblock(context, ctx->keyblock);
    free(ctx);
}

/*
 *
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req(krb5_context context,
	    krb5_auth_context *auth_context,
	    const krb5_data *inbuf,
	    krb5_const_principal server,
	    krb5_keytab keytab,
	    krb5_flags *ap_req_options,
	    krb5_ticket **ticket)
{
    krb5_error_code ret;
    krb5_rd_req_in_ctx in;
    krb5_rd_req_out_ctx out;

    ret = krb5_rd_req_in_ctx_alloc(context, &in);
    if (ret)
	return ret;
    
    ret = krb5_rd_req_in_set_keytab(context, in, keytab);
    if (ret) {
	krb5_rd_req_in_ctx_free(context, in);
	return ret;
    }

    ret = krb5_rd_req_ctx(context, auth_context, inbuf, server, in, &out);
    krb5_rd_req_in_ctx_free(context, in);
    if (ret)
	return ret;

    if (ap_req_options)
	*ap_req_options = out->ap_req_options;
    if (ticket) {
	ret = krb5_copy_ticket(context, out->ticket, ticket);
	if (ret)
	    goto out;
    }

out:
    krb5_rd_req_out_ctx_free(context, out);
    return ret;
}

/*
 *
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_with_keyblock(krb5_context context,
			  krb5_auth_context *auth_context,
			  const krb5_data *inbuf,
			  krb5_const_principal server,
			  krb5_keyblock *keyblock,
			  krb5_flags *ap_req_options,
			  krb5_ticket **ticket)
{
    krb5_error_code ret;
    krb5_rd_req_in_ctx in;
    krb5_rd_req_out_ctx out;

    ret = krb5_rd_req_in_ctx_alloc(context, &in);
    if (ret)
	return ret;
    
    ret = krb5_rd_req_in_set_keyblock(context, in, keyblock);
    if (ret) {
	krb5_rd_req_in_ctx_free(context, in);
	return ret;
    }

    ret = krb5_rd_req_ctx(context, auth_context, inbuf, server, in, &out);
    krb5_rd_req_in_ctx_free(context, in);
    if (ret)
	return ret;

    if (ap_req_options)
	*ap_req_options = out->ap_req_options;
    if (ticket) {
	ret = krb5_copy_ticket(context, out->ticket, ticket);
	if (ret)
	    goto out;
    }

out:
    krb5_rd_req_out_ctx_free(context, out);
    return ret;
}

/*
 *
 */

static krb5_error_code
get_key_from_keytab(krb5_context context,
		    krb5_auth_context *auth_context,
		    krb5_ap_req *ap_req,
		    krb5_const_principal server,
		    krb5_keytab keytab,
		    krb5_keyblock **out_key)
{
    krb5_keytab_entry entry;
    krb5_error_code ret;
    int kvno;
    krb5_keytab real_keytab;

    if(keytab == NULL)
	krb5_kt_default(context, &real_keytab);
    else
	real_keytab = keytab;
    
    if (ap_req->ticket.enc_part.kvno)
	kvno = *ap_req->ticket.enc_part.kvno;
    else
	kvno = 0;

    ret = krb5_kt_get_entry (context,
			     real_keytab,
			     server,
			     kvno,
			     ap_req->ticket.enc_part.etype,
			     &entry);
    if(ret)
	goto out;
    ret = krb5_copy_keyblock(context, &entry.keyblock, out_key);
    krb5_kt_free_entry (context, &entry);
out:    
    if(keytab == NULL)
	krb5_kt_close(context, real_keytab);
    
    return ret;
}

/*
 *
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_req_ctx(krb5_context context,
		krb5_auth_context *auth_context,
		const krb5_data *inbuf,
		krb5_const_principal server,
		krb5_rd_req_in_ctx inctx,
		krb5_rd_req_out_ctx *outctx)
{
    krb5_error_code ret;
    krb5_ap_req ap_req;
    krb5_principal service = NULL;
    krb5_rd_req_out_ctx o = NULL;

    ret = _krb5_rd_req_out_ctx_alloc(context, &o);
    if (ret)
	goto out;

    if (*auth_context == NULL) {
	ret = krb5_auth_con_init(context, auth_context);
	if (ret)
	    goto out;
    }

    ret = krb5_decode_ap_req(context, inbuf, &ap_req);
    if(ret)
	goto out;

    if(server == NULL){
	ret = _krb5_principalname2krb5_principal(context,
						 &service,
						 ap_req.ticket.sname,
						 ap_req.ticket.realm);
	if (ret)
	    goto out;
	server = service;
    }
    if (ap_req.ap_options.use_session_key &&
	(*auth_context)->keyblock == NULL) {
	krb5_set_error_string(context, "krb5_rd_req: user to user auth "
			      "without session key given");
	ret = KRB5KRB_AP_ERR_NOKEY;
	goto out;
    }

    if((*auth_context)->keyblock){
	ret = krb5_copy_keyblock(context,
				 (*auth_context)->keyblock,
				 &o->keyblock);
	if (ret)
	    goto out;
    } else if(inctx->keyblock){
	ret = krb5_copy_keyblock(context,
				 inctx->keyblock,
				 &o->keyblock);
	if (ret)
	    goto out;
    } else {
	krb5_keytab keytab = NULL;

	if (inctx && inctx->keytab)
	    keytab = inctx->keytab;

	ret = get_key_from_keytab(context, 
				  auth_context, 
				  &ap_req,
				  server,
				  keytab,
				  &o->keyblock);
	if(ret)
	    goto out;
    }

    ret = krb5_verify_ap_req2(context,
			      auth_context,
			      &ap_req,
			      server,
			      o->keyblock,
			      0,
			      &o->ap_req_options,
			      &o->ticket,
			      KRB5_KU_AP_REQ_AUTH);

    if (ret)
	goto out;

    /* If there is a PAC, verify its server signature */
    if (inctx->check_pac) {
	krb5_pac pac;
	krb5_data data;

	ret = krb5_ticket_get_authorization_data_type(context,
						      o->ticket,
						      KRB5_AUTHDATA_WIN2K_PAC,
						      &data);
	if (ret == 0) {
	    ret = krb5_pac_parse(context, data.data, data.length, &pac);
	    krb5_data_free(&data);
	    if (ret)
		goto out;
	
	    ret = krb5_pac_verify(context,
				  pac, 
				  o->ticket->ticket.authtime,
				  o->ticket->client, 
				  o->keyblock, 
				  NULL);
	    krb5_pac_free(context, pac);
	    if (ret)
		goto out;
	}
	ret = 0;
    }
out:
    if (ret || outctx == NULL) {
	krb5_rd_req_out_ctx_free(context, o);
    } else 
	*outctx = o;

    free_AP_REQ(&ap_req);
    if(service)
	krb5_free_principal(context, service);
    return ret;
}