/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * Authentication redirection virtual channel

 *

 * Copyright 2023 David Fort <contact@hardening-consulting.com>

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <krb5.h>

#include <errno.h>

#include <winpr/assert.h>

#include <winpr/wtypes.h>

#include <winpr/crt.h>

#include <winpr/wlog.h>

#include <winpr/print.h>

#include <winpr/asn1.h>

#include <winpr/sspi.h>

#include <winpr/collections.h>

#include <rdpear-common/ndr.h>

#include <rdpear-common/rdpear_common.h>

#include <rdpear-common/rdpear_asn1.h>

#include <freerdp/config.h>

#include <freerdp/freerdp.h>

#include <freerdp/addin.h>

#include <freerdp/client/channels.h>

#include <freerdp/channels/log.h>

#include <freerdp/channels/rdpear.h>

#define TAG CHANNELS_TAG("rdpear.client")

#ifndef MAX_KEYTAB_NAME_LEN

#define MAX_KEYTAB_NAME_LEN 1100 /* Defined in MIT krb5.h */

#endif

/* defined in libkrb5 */

krb5_error_code encode_krb5_authenticator(const krb5_authenticator* rep, krb5_data** code_out);

krb5_error_code encode_krb5_ap_rep(const krb5_ap_rep* rep, krb5_data** code_out);

typedef struct

{

  GENERIC_DYNVC_PLUGIN base;

  rdpContext* rdp_context;

  krb5_context krbContext;

} RDPEAR_PLUGIN;

static const BYTE payloadHeader[16] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                                      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

static krb5_error_code RPC_ENCRYPTION_KEY_to_keyblock(krb5_context ctx,

                                                      const KERB_RPC_ENCRYPTION_KEY* key,

                                                      krb5_keyblock** pkeyblock)

{

  WINPR_ASSERT(ctx);

  WINPR_ASSERT(key);

  WINPR_ASSERT(pkeyblock);

  if (!key->reserved3.length)

    return KRB5KDC_ERR_NULL_KEY;

  krb5_error_code rv =

      krb5_init_keyblock(ctx, (krb5_enctype)key->reserved2, key->reserved3.length, pkeyblock);

  if (rv)

    return rv;

  krb5_keyblock* keyblock = *pkeyblock;

  memcpy(keyblock->contents, key->reserved3.value, key->reserved3.length);

  return rv;

}

static krb5_error_code kerb_do_checksum(krb5_context ctx, const KERB_RPC_ENCRYPTION_KEY* key,

                                        krb5_keyusage kusage, krb5_cksumtype cksumtype,

                                        const KERB_ASN1_DATA* plain, krb5_checksum* out)

{

  WINPR_ASSERT(ctx);

  WINPR_ASSERT(key);

  WINPR_ASSERT(plain);

  WINPR_ASSERT(out);

  krb5_keyblock* keyblock = NULL;

  krb5_data data = { 0 };

  krb5_error_code rv = RPC_ENCRYPTION_KEY_to_keyblock(ctx, key, &keyblock);

  if (rv)

    return rv;

  data.data = (char*)plain->Asn1Buffer;

  data.length = plain->Asn1BufferHints.count;

  rv = krb5_c_make_checksum(ctx, cksumtype, keyblock, kusage, &data, out);

  krb5_free_keyblock(ctx, keyblock);

  return rv;

}

static krb5_error_code kerb_do_encrypt(krb5_context ctx, const KERB_RPC_ENCRYPTION_KEY* key,

                                       krb5_keyusage kusage, const KERB_ASN1_DATA* plain,

                                       krb5_data* out)

{

  WINPR_ASSERT(ctx);

  WINPR_ASSERT(key);

  WINPR_ASSERT(plain);

  WINPR_ASSERT(out);

  krb5_keyblock* keyblock = NULL;

  krb5_data data = { 0 };

  krb5_enc_data enc = { 0 };

  size_t elen = 0;

  krb5_error_code rv = RPC_ENCRYPTION_KEY_to_keyblock(ctx, key, &keyblock);

  if (rv)

    return rv;

  data.data = (char*)plain->Asn1Buffer;

  data.length = plain->Asn1BufferHints.count;

  rv = krb5_c_encrypt_length(ctx, keyblock->enctype, data.length, &elen);

  if (rv)

    goto out;

  if (!elen || (elen > UINT32_MAX))

  {

    rv = KRB5_PARSE_MALFORMED;

    goto out;

  }

  enc.ciphertext.length = (unsigned int)elen;

  enc.ciphertext.data = malloc(elen);

  if (!enc.ciphertext.data)

  {

    rv = ENOMEM;

    goto out;

  }

  rv = krb5_c_encrypt(ctx, keyblock, kusage, NULL, &data, &enc);

  out->data = enc.ciphertext.data;

  out->length = enc.ciphertext.length;

out:

  krb5_free_keyblock(ctx, keyblock);

  return rv;

}

static krb5_error_code kerb_do_decrypt(krb5_context ctx, const KERB_RPC_ENCRYPTION_KEY* key,

                                       krb5_keyusage kusage, const krb5_data* cipher,

                                       KERB_ASN1_DATA* plain)

{

  WINPR_ASSERT(ctx);

  WINPR_ASSERT(key);

  WINPR_ASSERT(cipher);

  WINPR_ASSERT(cipher->length);

  WINPR_ASSERT(plain);

  krb5_keyblock* keyblock = NULL;

  krb5_data data = { 0 };

  krb5_enc_data enc = { 0 };

  krb5_error_code rv = RPC_ENCRYPTION_KEY_to_keyblock(ctx, key, &keyblock);

  if (rv)

    return rv;

  enc.kvno = KRB5_PVNO;

  enc.enctype = (krb5_enctype)key->reserved2;

  enc.ciphertext.length = cipher->length;

  enc.ciphertext.data = cipher->data;

  data.length = cipher->length;

  data.data = (char*)malloc(cipher->length);

  if (!data.data)

  {

    rv = ENOMEM;

    goto out;

  }

  rv = krb5_c_decrypt(ctx, keyblock, kusage, NULL, &enc, &data);

  plain->Asn1Buffer = (BYTE*)data.data;

  plain->Asn1BufferHints.count = data.length;

out:

  krb5_free_keyblock(ctx, keyblock);

  return rv;

}

static BOOL rdpear_send_payload(RDPEAR_PLUGIN* rdpear, IWTSVirtualChannelCallback* pChannelCallback,

                                RdpEarPackageType packageType, wStream* payload)

{

  GENERIC_CHANNEL_CALLBACK* callback = (GENERIC_CHANNEL_CALLBACK*)pChannelCallback;

  BOOL ret = FALSE;

  wStream* finalStream = NULL;

  SecBuffer cryptedBuffer = { 0 };

  wStream* unencodedContent = rdpear_encodePayload(packageType, payload);

  if (!unencodedContent)

    goto out;

  const size_t unencodedLen = Stream_GetPosition(unencodedContent);

#if UINT32_MAX < SIZE_MAX

  if (unencodedLen > UINT32_MAX)

    goto out;

#endif

  SecBuffer inBuffer = { (ULONG)unencodedLen, SECBUFFER_DATA, Stream_Buffer(unencodedContent) };

  if (!freerdp_nla_encrypt(rdpear->rdp_context, &inBuffer, &cryptedBuffer))

    goto out;

  finalStream = Stream_New(NULL, 200);

  if (!finalStream)

    goto out;

  Stream_Write_UINT32(finalStream, 0x4EACC3C8);             /* ProtocolMagic (4 bytes) */

  Stream_Write_UINT32(finalStream, cryptedBuffer.cbBuffer); /* Length (4 bytes) */

  Stream_Write_UINT32(finalStream, 0x00000000);             /* Version (4 bytes) */

  Stream_Write_UINT32(finalStream, 0x00000000);             /* Reserved (4 bytes) */

  Stream_Write_UINT64(finalStream, 0);                      /* TsPkgContext (8 bytes) */

  /* payload */

  if (!Stream_EnsureRemainingCapacity(finalStream, cryptedBuffer.cbBuffer))

    goto out;

  Stream_Write(finalStream, cryptedBuffer.pvBuffer, cryptedBuffer.cbBuffer);

  const size_t pos = Stream_GetPosition(finalStream);

#if UINT32_MAX < SIZE_MAX

  if (pos > UINT32_MAX)

    goto out;

#endif

  UINT status =

      callback->channel->Write(callback->channel, (ULONG)pos, Stream_Buffer(finalStream), NULL);

  ret = (status == CHANNEL_RC_OK);

  if (!ret)

    WLog_DBG(TAG, "rdpear_send_payload=0x%x", status);

out:

  sspi_SecBufferFree(&cryptedBuffer);

  Stream_Free(unencodedContent, TRUE);

  Stream_Free(finalStream, TRUE);

  return ret;

}

static BOOL rdpear_prepare_response(NdrContext* rcontext, UINT16 callId, UINT32 status,

                                    NdrContext** pwcontext, wStream* retStream)

{

  WINPR_ASSERT(rcontext);

  WINPR_ASSERT(pwcontext);

  BOOL ret = FALSE;

  *pwcontext = NULL;

  NdrContext* wcontext = ndr_context_copy(rcontext);

  if (!wcontext)

    return FALSE;

  if (!Stream_EnsureRemainingCapacity(retStream, sizeof(payloadHeader)))

    goto out;

  Stream_Write(retStream, payloadHeader, sizeof(payloadHeader));

  if (!ndr_write_header(wcontext, retStream) || !ndr_start_constructed(wcontext, retStream) ||

      !ndr_write_pickle(wcontext, retStream) ||         /* pickle header */

      !ndr_write_uint16(wcontext, retStream, callId) || /* callId */

      !ndr_write_uint16(wcontext, retStream, 0x0000) || /* align padding */

      !ndr_write_uint32(wcontext, retStream, status) || /* status */

      !ndr_write_uint16(wcontext, retStream, callId) || /* callId */

      !ndr_write_uint16(wcontext, retStream, 0x0000))   /* align padding */

    goto out;

  *pwcontext = wcontext;

  ret = TRUE;

out:

  if (!ret)

    ndr_context_destroy(&wcontext);

  return ret;

}

static BOOL rdpear_kerb_version(NdrContext* rcontext, wStream* s, UINT32* pstatus, UINT32* pversion)

{

  *pstatus = ERROR_INVALID_DATA;

  if (!ndr_read_uint32(rcontext, s, pversion))

    return TRUE;

  WLog_DBG(TAG, "-> KerbNegotiateVersion(v=0x%x)", *pversion);

  *pstatus = 0;

  return TRUE;

}

static BOOL rdpear_kerb_ComputeTgsChecksum(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext, wStream* s,

                                           UINT32* pstatus, KERB_ASN1_DATA* resp)

{

  ComputeTgsChecksumReq req = { 0 };

  krb5_checksum checksum = { 0 };

  wStream* asn1Payload = NULL;

  *pstatus = ERROR_INVALID_DATA;

  WLog_DBG(TAG, "-> ComputeTgsChecksum");

  if (!ndr_read_ComputeTgsChecksumReq(rcontext, s, NULL, &req) ||

      !ndr_treat_deferred_read(rcontext, s))

    goto out;

  // ComputeTgsChecksumReq_dump(WLog_Get(""), WLOG_DEBUG, &req);

  krb5_error_code rv =

      kerb_do_checksum(rdpear->krbContext, req.Key, KRB5_KEYUSAGE_TGS_REQ_AUTH_CKSUM,

                       (krb5_cksumtype)req.ChecksumType, req.requestBody, &checksum);

  if (rv)

    goto out;

  asn1Payload = rdpear_enc_Checksum(req.ChecksumType, &checksum);

  if (!asn1Payload)

    goto out;

  resp->Pdu = 8;

  resp->Asn1Buffer = Stream_Buffer(asn1Payload);

  const size_t pos = Stream_GetPosition(asn1Payload);

  if (pos > UINT32_MAX)

    goto out;

  resp->Asn1BufferHints.count = (UINT32)pos;

  *pstatus = 0;

out:

  ndr_destroy_ComputeTgsChecksumReq(rcontext, NULL, &req);

  krb5_free_checksum_contents(rdpear->krbContext, &checksum);

  Stream_Free(asn1Payload, FALSE);

  return TRUE;

}

static BOOL rdpear_kerb_BuildEncryptedAuthData(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext,

                                               wStream* s, UINT32* pstatus, KERB_ASN1_DATA* asn1)

{

  BuildEncryptedAuthDataReq req = { 0 };

  krb5_data encrypted = { 0 };

  wStream* asn1Payload = NULL;

  krb5_error_code rv = 0;

  *pstatus = ERROR_INVALID_DATA;

  WLog_DBG(TAG, "-> BuildEncryptedAuthData");

  if (!ndr_read_BuildEncryptedAuthDataReq(rcontext, s, NULL, &req) ||

      !ndr_treat_deferred_read(rcontext, s))

    goto out;

  rv = kerb_do_encrypt(rdpear->krbContext, req.Key, (krb5_keyusage)req.KeyUsage,

                       req.PlainAuthData, &encrypted);

  if (rv)

    goto out;

  /* do the encoding */

  asn1Payload = rdpear_enc_EncryptedData(req.Key->reserved2, &encrypted);

  if (!asn1Payload)

    goto out;

  //  WLog_DBG(TAG, "rdpear_kerb_BuildEncryptedAuthData resp=");

  //  winpr_HexDump(TAG, WLOG_DEBUG, Stream_Buffer(asn1Payload), Stream_GetPosition(asn1Payload));

  asn1->Pdu = 6;

  asn1->Asn1Buffer = Stream_Buffer(asn1Payload);

  const size_t pos = Stream_GetPosition(asn1Payload);

  if (pos > UINT32_MAX)

    goto out;

  asn1->Asn1BufferHints.count = (UINT32)pos;

  *pstatus = 0;

out:

  krb5_free_data_contents(rdpear->krbContext, &encrypted);

  ndr_destroy_BuildEncryptedAuthDataReq(rcontext, NULL, &req);

  Stream_Free(asn1Payload, FALSE);

  return TRUE;

}

static char* KERB_RPC_UNICODESTR_to_charptr(const RPC_UNICODE_STRING* src)

{

  WINPR_ASSERT(src);

  return ConvertWCharNToUtf8Alloc(src->Buffer, src->strLength, NULL);

}

static BOOL extractAuthData(const KERB_ASN1_DATA* src, krb5_authdata* authData, BOOL* haveData)

{

  WinPrAsn1Decoder dec = { 0 };

  WinPrAsn1Decoder dec2 = { 0 };

  WinPrAsn1Decoder dec3 = { 0 };

  WinPrAsn1Decoder_InitMem(&dec, WINPR_ASN1_DER, src->Asn1Buffer, src->Asn1BufferHints.count);

  BOOL error = FALSE;

  WinPrAsn1_INTEGER adType = 0;

  WinPrAsn1_OctetString os = { 0 };

  *haveData = FALSE;

  if (!WinPrAsn1DecReadSequence(&dec, &dec2))

    return FALSE;

  wStream subStream = WinPrAsn1DecGetStream(&dec2);

  if (!Stream_GetRemainingLength(&subStream))

    return TRUE;

  if (!WinPrAsn1DecReadSequence(&dec2, &dec3))

    return FALSE;

  if (!WinPrAsn1DecReadContextualInteger(&dec3, 0, &error, &adType) ||

      !WinPrAsn1DecReadContextualOctetString(&dec3, 1, &error, &os, FALSE))

    return FALSE;

  if (os.len > UINT32_MAX)

    return FALSE;

  authData->ad_type = adType;

  authData->length = (unsigned int)os.len;

  authData->contents = os.data;

  *haveData = TRUE;

  return TRUE;

}

static BOOL extractChecksum(const KERB_ASN1_DATA* src, krb5_checksum* dst)

{

  WinPrAsn1Decoder dec = { 0 };

  WinPrAsn1Decoder dec2 = { 0 };

  WinPrAsn1Decoder_InitMem(&dec, WINPR_ASN1_DER, src->Asn1Buffer, src->Asn1BufferHints.count);

  BOOL error = FALSE;

  WinPrAsn1_OctetString os;

  if (!WinPrAsn1DecReadSequence(&dec, &dec2))

    return FALSE;

  WinPrAsn1_INTEGER cksumtype = 0;

  if (!WinPrAsn1DecReadContextualInteger(&dec2, 0, &error, &cksumtype) ||

      !WinPrAsn1DecReadContextualOctetString(&dec2, 1, &error, &os, FALSE))

    return FALSE;

  if (os.len > UINT32_MAX)

    return FALSE;

  dst->checksum_type = cksumtype;

  dst->length = (unsigned int)os.len;

  dst->contents = os.data;

  return TRUE;

}

#define FILETIME_TO_UNIX_OFFSET_S 11644473600LL

static LONGLONG krb5_time_to_FILETIME(const krb5_timestamp* ts, krb5_int32 usec)

{

  WINPR_ASSERT(ts);

  return (((*ts + FILETIME_TO_UNIX_OFFSET_S) * (1000LL * 1000LL) + usec) * 10LL);

}

static void krb5_free_principal_contents(krb5_context ctx, krb5_principal principal)

{

  WINPR_ASSERT(principal);

  krb5_free_data_contents(ctx, &principal->realm);

  krb5_free_data(ctx, principal->data);

}

static BOOL rdpear_kerb_CreateApReqAuthenticator(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext,

                                                 wStream* s, UINT32* pstatus,

                                                 CreateApReqAuthenticatorResp* resp)

{

  krb5_error_code rv = 0;

  wStream* asn1EncodedAuth = NULL;

  CreateApReqAuthenticatorReq req = { 0 };

  krb5_data authenticator = { 0 };

  krb5_data* der = NULL;

  krb5_keyblock* subkey = NULL;

  krb5_principal_data client = { 0 };

  *pstatus = ERROR_INVALID_DATA;

  WLog_DBG(TAG, "-> CreateApReqAuthenticator");

  if (!ndr_read_CreateApReqAuthenticatorReq(rcontext, s, NULL, &req) ||

      !ndr_treat_deferred_read(rcontext, s))

    goto out;

  krb5_authdata authdata = { 0 };

  krb5_authdata* authDataPtr[2] = { &authdata, NULL };

  BOOL haveData = 0;

  if (!extractAuthData(req.AuthData, &authdata, &haveData))

  {

    WLog_ERR(TAG, "error retrieving auth data");

    winpr_HexDump(TAG, WLOG_DEBUG, req.AuthData->Asn1Buffer,

                  req.AuthData->Asn1BufferHints.count);

    goto out;

  }

  if (req.SkewTime->QuadPart)

  {

    WLog_ERR(TAG, "!!!!! should handle SkewTime !!!!!");

  }

  if (req.SubKey)

  {

    rv = RPC_ENCRYPTION_KEY_to_keyblock(rdpear->krbContext, req.SubKey, &subkey);

    if (rv)

    {

      WLog_ERR(TAG, "error importing subkey");

      goto out;

    }

  }

  krb5_authenticator authent = { .checksum = NULL,

                               .subkey = NULL,

                               .seq_number = req.SequenceNumber,

                               .authorization_data = haveData ? authDataPtr : NULL };

  client.type = req.ClientName->NameType;

  if (req.ClientName->nameHints.count > INT32_MAX)

    goto out;

  client.length = (krb5_int32)req.ClientName->nameHints.count;

  client.data = calloc(req.ClientName->nameHints.count, sizeof(krb5_data));

  if (!client.data)

    goto out;

  for (int i = 0; i < client.length; i++)

  {

    krb5_data* cur = &client.data[i];

    cur->data = KERB_RPC_UNICODESTR_to_charptr(&req.ClientName->Names[i]);

    if (!cur->data)

      goto out;

    const size_t len = strnlen(cur->data, MAX_KEYTAB_NAME_LEN + 1);

    if (len > MAX_KEYTAB_NAME_LEN)

    {

      WLog_ERR(TAG,

               "Invalid ClientName length %" PRIuz

               ", limited to %u characters. ClientName: (%s)",

               MAX_KEYTAB_NAME_LEN, len, cur->data);

      goto out;

    }

    cur->length = (unsigned int)len;

  }

  client.realm.data = KERB_RPC_UNICODESTR_to_charptr(req.ClientRealm);

  if (!client.realm.data)

    goto out;

  const size_t len = strnlen(client.realm.data, MAX_KEYTAB_NAME_LEN + 1);

  if (len > MAX_KEYTAB_NAME_LEN)

  {

    WLog_ERR(TAG, "Invalid realm length %" PRIuz ", limited to %u characters. Realm: (%s)",

             MAX_KEYTAB_NAME_LEN, len, client.realm.data);

    goto out;

  }

  client.realm.length = (unsigned int)len;

  authent.client = &client;

  krb5_checksum checksum;

  krb5_checksum* pchecksum = NULL;

  if (req.GssChecksum)

  {

    if (!extractChecksum(req.GssChecksum, &checksum))

    {

      WLog_ERR(TAG, "Error getting the checksum");

      goto out;

    }

    pchecksum = &checksum;

  }

  authent.checksum = pchecksum;

  krb5_us_timeofday(rdpear->krbContext, &authent.ctime, &authent.cusec);

  rv = encode_krb5_authenticator(&authent, &der);

  if (rv)

  {

    WLog_ERR(TAG, "error encoding authenticator");

    goto out;

  }

  KERB_ASN1_DATA plain_authent = { .Pdu = 0,

                                 .Asn1Buffer = (BYTE*)der->data,

                                 .Asn1BufferHints = { .count = der->length } };

  rv = kerb_do_encrypt(rdpear->krbContext, req.EncryptionKey, (krb5_keyusage)req.KeyUsage,

                       &plain_authent, &authenticator);

  if (rv)

  {

    WLog_ERR(TAG, "error encrypting authenticator");

    goto out;

  }

  asn1EncodedAuth = rdpear_enc_EncryptedData(req.EncryptionKey->reserved2, &authenticator);

  if (!asn1EncodedAuth)

  {

    WLog_ERR(TAG, "error encoding to ASN1");

    rv = ENOMEM;

    goto out;

  }

  // WLog_DBG(TAG, "authenticator=");

  // winpr_HexDump(TAG, WLOG_DEBUG, Stream_Buffer(asn1EncodedAuth),

  // Stream_GetPosition(asn1EncodedAuth));

  const size_t size = Stream_GetPosition(asn1EncodedAuth);

  if (size > UINT32_MAX)

    goto out;

  resp->Authenticator.Asn1BufferHints.count = (UINT32)size;

  resp->Authenticator.Asn1Buffer = Stream_Buffer(asn1EncodedAuth);

  resp->AuthenticatorTime.QuadPart = krb5_time_to_FILETIME(&authent.ctime, authent.cusec);

  *pstatus = 0;

out:

  resp->Authenticator.Pdu = 6;

  resp->KerbProtocolError = rv;

  krb5_free_principal_contents(rdpear->krbContext, &client);

  krb5_free_data(rdpear->krbContext, der);

  krb5_free_data_contents(rdpear->krbContext, &authenticator);

  if (subkey)

    krb5_free_keyblock(rdpear->krbContext, subkey);

  ndr_destroy_CreateApReqAuthenticatorReq(rcontext, NULL, &req);

  Stream_Free(asn1EncodedAuth, FALSE);

  return TRUE;

}

static BOOL rdpear_findEncryptedData(const KERB_ASN1_DATA* src, int* penctype, krb5_data* data)

{

  WinPrAsn1Decoder dec = { 0 };

  WinPrAsn1Decoder dec2 = { 0 };

  WinPrAsn1Decoder_InitMem(&dec, WINPR_ASN1_DER, src->Asn1Buffer, src->Asn1BufferHints.count);

  BOOL error = FALSE;

  WinPrAsn1_INTEGER encType = 0;

  WinPrAsn1_OctetString os = { 0 };

  if (!WinPrAsn1DecReadSequence(&dec, &dec2) ||

      !WinPrAsn1DecReadContextualInteger(&dec2, 0, &error, &encType) ||

      !WinPrAsn1DecReadContextualOctetString(&dec2, 2, &error, &os, FALSE))

    return FALSE;

  if (os.len > UINT32_MAX)

    return FALSE;

  data->data = (char*)os.data;

  data->length = (unsigned int)os.len;

  *penctype = encType;

  return TRUE;

}

static BOOL rdpear_kerb_UnpackKdcReplyBody(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext, wStream* s,

                                           UINT32* pstatus, UnpackKdcReplyBodyResp* resp)

{

  UnpackKdcReplyBodyReq req = { 0 };

  *pstatus = ERROR_INVALID_DATA;

  if (!ndr_read_UnpackKdcReplyBodyReq(rcontext, s, NULL, &req) ||

      !ndr_treat_deferred_read(rcontext, s))

    goto out;

  if (req.StrengthenKey)

  {

    WLog_ERR(TAG, "StrengthenKey not supported yet");

    goto out;

  }

  WLog_DBG(TAG, "-> UnpackKdcReplyBody: KeyUsage=0x%x PDU=0x%x", req.KeyUsage, req.Pdu);

  // WLog_DBG(TAG, "encryptedPayload=");

  // winpr_HexDump(TAG, WLOG_DEBUG, req.EncryptedData->Asn1Buffer,

  // req.EncryptedData->Asn1BufferHints.count);

  krb5_data asn1Data = { 0 };

  int encType = 0;

  if (!rdpear_findEncryptedData(req.EncryptedData, &encType, &asn1Data) || !asn1Data.length)

    goto out;

  resp->KerbProtocolError = kerb_do_decrypt(

      rdpear->krbContext, req.Key, (krb5_keyusage)req.KeyUsage, &asn1Data, &resp->ReplyBody);

  resp->ReplyBody.Pdu = req.Pdu;

  *pstatus = 0;

out:

  ndr_destroy_UnpackKdcReplyBodyReq(rcontext, NULL, &req);

  return TRUE;

}

static BOOL rdpear_kerb_DecryptApReply(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext, wStream* s,

                                       UINT32* pstatus, KERB_ASN1_DATA* resp)

{

  DecryptApReplyReq req = { 0 };

  *pstatus = ERROR_INVALID_DATA;

  if (!ndr_read_DecryptApReplyReq(rcontext, s, NULL, &req) ||

      !ndr_treat_deferred_read(rcontext, s))

    goto out;

  WLog_DBG(TAG, "-> DecryptApReply");

  // winpr_HexDump(TAG, WLOG_DEBUG, req.EncryptedReply->Asn1Buffer,

  // req.EncryptedReply->Asn1BufferHints.count);

  krb5_data asn1Data = { 0 };

  int encType = 0;

  if (!rdpear_findEncryptedData(req.EncryptedReply, &encType, &asn1Data) || !asn1Data.length)

    goto out;

  resp->Pdu = 0x31;

  krb5_error_code rv =

      kerb_do_decrypt(rdpear->krbContext, req.Key, KRB5_KEYUSAGE_AP_REP_ENCPART, &asn1Data, resp);

  if (rv != 0)

  {

    WLog_ERR(TAG, "error decrypting");

    goto out;

  }

  // WLog_DBG(TAG, "response=");

  // winpr_HexDump(TAG, WLOG_DEBUG, resp->Asn1Buffer, resp->Asn1BufferHints.count);

  *pstatus = 0;

out:

  ndr_destroy_DecryptApReplyReq(rcontext, NULL, &req);

  return TRUE;

}

static BOOL rdpear_kerb_PackApReply(RDPEAR_PLUGIN* rdpear, NdrContext* rcontext, wStream* s,

                                    UINT32* pstatus, PackApReplyResp* resp)

{

  PackApReplyReq req = { 0 };

  krb5_data asn1Data = { 0 };

  krb5_data* out = NULL;

  WLog_DBG(TAG, "-> PackApReply");

  *pstatus = ERROR_INVALID_DATA;

  if (!ndr_read_PackApReplyReq(rcontext, s, NULL, &req) || !ndr_treat_deferred_read(rcontext, s))

    goto out;

  krb5_error_code rv = kerb_do_encrypt(rdpear->krbContext, req.SessionKey,

                                       KRB5_KEYUSAGE_AP_REP_ENCPART, req.ReplyBody, &asn1Data);

  if (rv)

    goto out;

  krb5_ap_rep reply;

  reply.enc_part.kvno = KRB5_PVNO;

  reply.enc_part.enctype = (krb5_enctype)req.SessionKey->reserved2;

  reply.enc_part.ciphertext.length = asn1Data.length;

  reply.enc_part.ciphertext.data = asn1Data.data;

  rv = encode_krb5_ap_rep(&reply, &out);

  if (rv)

    goto out;

  resp->PackedReply = (BYTE*)out->data;

  resp->PackedReplyHints.count = out->length;

  *pstatus = 0;

out:

  free(out);

  krb5_free_data_contents(rdpear->krbContext, &asn1Data);

  ndr_destroy_PackApReplyReq(rcontext, NULL, &req);

  return TRUE;

}

static UINT rdpear_decode_payload(RDPEAR_PLUGIN* rdpear,

                                  IWTSVirtualChannelCallback* pChannelCallback, wStream* s)

{

  UINT ret = ERROR_INVALID_DATA;

  NdrContext* context = NULL;

  NdrContext* wcontext = NULL;

  UINT32 status = 0;

  UINT32 uint32Resp = 0;

  KERB_ASN1_DATA asn1Data = { 0 };

  CreateApReqAuthenticatorResp createApReqAuthenticatorResp = { 0 };

  UnpackKdcReplyBodyResp unpackKdcReplyBodyResp = { 0 };

  PackApReplyResp packApReplyResp = { 0 };

  void* resp = NULL;

  NdrMessageType respDescr = NULL;

  wStream* respStream = Stream_New(NULL, 500);

  if (!respStream)

    goto out;

  Stream_Seek(s, 16); /* skip first 16 bytes */

  wStream commandStream = { 0 };

  UINT16 callId = 0;

  UINT16 callId2 = 0;

  context = ndr_read_header(s);

  if (!context || !ndr_read_constructed(context, s, &commandStream) ||

      !ndr_read_pickle(context, &commandStream) ||

      !ndr_read_uint16(context, &commandStream, &callId) ||

      !ndr_read_uint16(context, &commandStream, &callId2) || (callId != callId2))

    goto out;

  ret = CHANNEL_RC_NOT_OPEN;

  switch (callId)

  {

    case RemoteCallKerbNegotiateVersion:

      resp = &uint32Resp;

      respDescr = ndr_uint32_descr();

      if (rdpear_kerb_version(context, &commandStream, &status, &uint32Resp))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbCreateApReqAuthenticator:

      resp = &createApReqAuthenticatorResp;

      respDescr = ndr_CreateApReqAuthenticatorResp_descr();

      if (rdpear_kerb_CreateApReqAuthenticator(rdpear, context, &commandStream, &status,

                                               &createApReqAuthenticatorResp))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbDecryptApReply:

      resp = &asn1Data;

      respDescr = ndr_KERB_ASN1_DATA_descr();

      if (rdpear_kerb_DecryptApReply(rdpear, context, &commandStream, &status, &asn1Data))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbComputeTgsChecksum:

      resp = &asn1Data;

      respDescr = ndr_KERB_ASN1_DATA_descr();

      if (rdpear_kerb_ComputeTgsChecksum(rdpear, context, &commandStream, &status, &asn1Data))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbBuildEncryptedAuthData:

      resp = &asn1Data;

      respDescr = ndr_KERB_ASN1_DATA_descr();

      if (rdpear_kerb_BuildEncryptedAuthData(rdpear, context, &commandStream, &status,

                                             &asn1Data))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbUnpackKdcReplyBody:

      resp = &unpackKdcReplyBodyResp;

      respDescr = ndr_UnpackKdcReplyBodyResp_descr();

      if (rdpear_kerb_UnpackKdcReplyBody(rdpear, context, &commandStream, &status,

                                         &unpackKdcReplyBodyResp))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallKerbPackApReply:

      resp = &packApReplyResp;

      respDescr = ndr_PackApReplyResp_descr();

      if (rdpear_kerb_PackApReply(rdpear, context, &commandStream, &status, &packApReplyResp))

        ret = CHANNEL_RC_OK;

      break;

    case RemoteCallNtlmNegotiateVersion:

      WLog_ERR(TAG, "don't wanna support NTLM");

      break;

    default:

      WLog_DBG(TAG, "Unhandled callId=0x%x", callId);

      winpr_HexDump(TAG, WLOG_DEBUG, Stream_PointerAs(&commandStream, BYTE),

                    Stream_GetRemainingLength(&commandStream));

      break;

  }

  if (!rdpear_prepare_response(context, callId, status, &wcontext, respStream))

    goto out;

  if (resp && respDescr)

  {

    WINPR_ASSERT(respDescr->writeFn);

    BOOL r = respDescr->writeFn(wcontext, respStream, NULL, resp) &&

             ndr_treat_deferred_write(wcontext, respStream);

    if (respDescr->destroyFn)

      respDescr->destroyFn(wcontext, NULL, resp);

    if (!r)

    {

      WLog_DBG(TAG, "!writeFn || !ndr_treat_deferred_write");

      goto out;

    }

  }

  if (!ndr_end_constructed(wcontext, respStream) ||

      !rdpear_send_payload(rdpear, pChannelCallback, RDPEAR_PACKAGE_KERBEROS, respStream))

  {

    WLog_DBG(TAG, "rdpear_send_payload !!!!!!!!");

    goto out;