/*
 * 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"

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 = decode_EncTicketPart(plain.data, plain.length, decr_part, &len);
    if (ret)
        krb5_set_error_message(context, ret,
                               N_("Failed to decode encrypted "
                                  "ticket part", ""));
    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 = decode_Authenticator(plain.data, plain.length,
                               authenticator, &len);
    krb5_data_free (&plain);
    return ret;
}

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_message (context);
        return KRB5KRB_AP_ERR_BADVERSION;
    }
    if (ap_req->msg_type != krb_ap_req){
        free_AP_REQ(ap_req);
        krb5_clear_error_message (context);
        return KRB5KRB_AP_ERR_MSG_TYPE;
    }
    if (ap_req->ticket.tkt_vno != 5){
        free_AP_REQ(ap_req);
        krb5_clear_error_message (context);
        return KRB5KRB_AP_ERR_BADVERSION;
    }
    return 0;
}

static krb5_error_code
check_transited(krb5_context context, Ticket *ticket, EncTicketPart *enc)
{
    char **realms;
    unsigned int num_realms, n;
    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);
    for (n = 0; n < num_realms; n++)
        free(realms[n]);
    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;

    memset(&adIfRelevant, 0, sizeof(adIfRelevant));

    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_message(context);

    free_AD_IF_RELEVANT(&adIfRelevant);

    return ret;
}

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_message (context);
            return KRB5KRB_AP_ERR_TKT_NYV;
        }
        if(now - t.endtime > context->max_skew) {
            free_EncTicketPart(&t);
            krb5_clear_error_message (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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_message (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;

    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_message (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_message (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_message (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) {
        size_t i;

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

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

    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_principal server;
};

/**
 * Allocate a krb5_rd_req_in_ctx as an input parameter to
 * krb5_rd_req_ctx(). The caller should free the context with
 * krb5_rd_req_in_ctx_free() when done with the context.
 *
 * @param context Keberos 5 context.
 * @param ctx in ctx to krb5_rd_req_ctx().
 *
 * @return Kerberos 5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_auth
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    (*ctx)->check_pac = (context->flags & KRB5_CTX_F_CHECK_PAC) ? 1 : 0;
    return 0;
}

/**
 * Set the keytab that krb5_rd_req_ctx() will use.
 *
 * @param context Keberos 5 context.
 * @param in in ctx to krb5_rd_req_ctx().
 * @param keytab keytab that krb5_rd_req_ctx() will use, only copy the
 *        pointer, so the caller must free they keytab after
 *        krb5_rd_req_in_ctx_free() is called.
 *
 * @return Kerberos 5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_auth
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_rd_req_in_set_keytab(krb5_context context,
                          krb5_rd_req_in_ctx in,
                          krb5_keytab keytab)
{
    in->keytab = keytab;
    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_auth
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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);
}

/**
 * Get the principal that was used in the request from the
 * client. Might not match whats in the ticket if krb5_rd_req_ctx()
 * searched in the keytab for a matching key.
 *
 * @param context a Kerberos 5 context.
 * @param out a krb5_rd_req_out_ctx from krb5_rd_req_ctx().
 * @param principal return principal, free with krb5_free_principal().
 *
 * @ingroup krb5_auth
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_rd_req_out_get_server(krb5_context context,
                            krb5_rd_req_out_ctx out,
                            krb5_principal *principal)
{
    return krb5_copy_principal(context, out->server, principal);
}

KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_rd_req_in_ctx_free(krb5_context context, krb5_rd_req_in_ctx ctx)
{
    free(ctx);
}

/**
 * Free the krb5_rd_req_out_ctx.
 *
 * @param context Keberos 5 context.
 * @param ctx krb5_rd_req_out_ctx context to free.
 *
 * @ingroup krb5_auth
 */

KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_rd_req_out_ctx_free(krb5_context context, krb5_rd_req_out_ctx ctx)
{
    if (ctx->ticket)
        krb5_free_ticket(context, ctx->ticket);
    if (ctx->keyblock)
        krb5_free_keyblock(context, ctx->keyblock);
    if (ctx->server)
        krb5_free_principal(context, ctx->server);
    free(ctx);
}

/*
 *
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_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 == 0) {
        ret = krb5_copy_keyblock(context, &entry.keyblock, out_key);
        krb5_kt_free_entry(context, &entry);
    }
    if(keytab == NULL)
        krb5_kt_close(context, real_keytab);

    return ret;
}

/**
 * The core server function that verify application authentication
 * requests from clients.
 *
 * @param context Keberos 5 context.
 * @param auth_context the authentication context, can be NULL, then
 *        default values for the authentication context will used.
 * @param inbuf the (AP-REQ) authentication buffer
 *
 * @param server the server with authenticate as, if NULL the function
 *        will try to find any available credential in the keytab
 *        that will verify the reply. The function will prefer the
 *        server the server client specified in the AP-REQ, but if
 *        there is no mach, it will try all keytab entries for a
 *        match. This have serious performance issues for larger keytabs.
 *
 * @param inctx control the behavior of the function, if NULL, the
 *        default behavior is used.
 * @param outctx the return outctx, free with krb5_rd_req_out_ctx_free().
 * @return Kerberos 5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_auth
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
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_rd_req_out_ctx o = NULL;
    krb5_keytab id = NULL, keytab = NULL;
    krb5_principal service = NULL;

    *outctx = NULL;

    o = calloc(1, sizeof(*o));
    if (o == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }

    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;

    /* Save that principal that was in the request */
    ret = _krb5_principalname2krb5_principal(context,
                                             &o->server,
                                             ap_req.ticket.sname,
                                             ap_req.ticket.realm);
    if (ret)
        goto out;

    if (ap_req.ap_options.use_session_key &&
        (*auth_context)->keyblock == NULL) {
        ret = KRB5KRB_AP_ERR_NOKEY;
        krb5_set_error_message(context, ret,
                               N_("krb5_rd_req: user to user auth "
                                  "without session key given", ""));
        goto out;
    }

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

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

        if(id == NULL) {
            krb5_kt_default(context, &keytab);
            id = keytab;
        }
        if (id == NULL)
            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;
        }

        ret = get_key_from_keytab(context,
                                  &ap_req,
                                  server,
                                  id,
                                  &o->keyblock);
        if (ret) {
            /* If caller specified a server, fail. */
            if (service == NULL && (context->flags & KRB5_CTX_F_RD_REQ_IGNORE) == 0)
                goto out;
            /* Otherwise, fall back to iterating over the keytab. This
             * have serious performace issues for larger keytab.
             */
            o->keyblock = NULL;
        }
    }

    if (o->keyblock) {
        /*
         * We got an exact keymatch, use that.
         */

        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;

    } else {
        /*
         * Interate over keytab to find a key that can decrypt the request.
         */

        krb5_keytab_entry entry;
        krb5_kt_cursor cursor;
        int done = 0, kvno = 0;

        memset(&cursor, 0, sizeof(cursor));

        if (ap_req.ticket.enc_part.kvno)
            kvno = *ap_req.ticket.enc_part.kvno;

        ret = krb5_kt_start_seq_get(context, id, &cursor);
        if (ret)
            goto out;

        done = 0;
        while (!done) {
            krb5_principal p;

            ret = krb5_kt_next_entry(context, id, &entry, &cursor);
            if (ret) {
                _krb5_kt_principal_not_found(context, ret, id, o->server,
                                             ap_req.ticket.enc_part.etype,
                                             kvno);
                goto out;
            }

            if (entry.keyblock.keytype != ap_req.ticket.enc_part.etype) {
                krb5_kt_free_entry (context, &entry);
                continue;
            }

            ret = krb5_verify_ap_req2(context,
                                      auth_context,
                                      &ap_req,
                                      server,
                                      &entry.keyblock,
                                      0,
                                      &o->ap_req_options,
                                      &o->ticket,
                                      KRB5_KU_AP_REQ_AUTH);
            if (ret) {
                krb5_kt_free_entry (context, &entry);
                continue;
            }

            /*
             * Found a match, save the keyblock for PAC processing,
             * and update the service principal in the ticket to match
             * whatever is in the keytab.
             */

            ret = krb5_copy_keyblock(context,
                                     &entry.keyblock,
                                     &o->keyblock);
            if (ret) {
                krb5_kt_free_entry (context, &entry);
                goto out;
            }

            ret = krb5_copy_principal(context, entry.principal, &p);
            if (ret) {
                krb5_kt_free_entry (context, &entry);
                goto out;
            }
            krb5_free_principal(context, o->ticket->server);
            o->ticket->server = p;

            krb5_kt_free_entry (context, &entry);

            done = 1;
        }
        krb5_kt_end_seq_get (context, id, &cursor);
    }

    /* If there is a PAC, verify its server signature */
    if (inctx == NULL || 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;
        } else
          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);

    if (keytab)
        krb5_kt_close(context, keytab);

    return ret;
}