/**
 * WinPR: Windows Portable Runtime
 * NTLM Security Package (Message)
 *
 * Copyright 2011-2014 Marc-Andre Moreau <marcandre.moreau@gmail.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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "ntlm.h"
#include "../sspi.h"

#include <winpr/crt.h>
#include <winpr/print.h>
#include <winpr/stream.h>
#include <winpr/sysinfo.h>

#include "ntlm_compute.h"

#include "ntlm_message.h"

#include "../log.h"
#define TAG WINPR_TAG("sspi.NTLM")

static const char NTLM_SIGNATURE[8] = { 'N', 'T', 'L', 'M', 'S', 'S', 'P', '\0' };

#ifdef WITH_DEBUG_NTLM
static const char* const NTLM_NEGOTIATE_STRINGS[] = { "NTLMSSP_NEGOTIATE_56",
	                                                  "NTLMSSP_NEGOTIATE_KEY_EXCH",
	                                                  "NTLMSSP_NEGOTIATE_128",
	                                                  "NTLMSSP_RESERVED1",
	                                                  "NTLMSSP_RESERVED2",
	                                                  "NTLMSSP_RESERVED3",
	                                                  "NTLMSSP_NEGOTIATE_VERSION",
	                                                  "NTLMSSP_RESERVED4",
	                                                  "NTLMSSP_NEGOTIATE_TARGET_INFO",
	                                                  "NTLMSSP_REQUEST_NON_NT_SESSION_KEY",
	                                                  "NTLMSSP_RESERVED5",
	                                                  "NTLMSSP_NEGOTIATE_IDENTIFY",
	                                                  "NTLMSSP_NEGOTIATE_EXTENDED_SESSION_SECURITY",
	                                                  "NTLMSSP_RESERVED6",
	                                                  "NTLMSSP_TARGET_TYPE_SERVER",
	                                                  "NTLMSSP_TARGET_TYPE_DOMAIN",
	                                                  "NTLMSSP_NEGOTIATE_ALWAYS_SIGN",
	                                                  "NTLMSSP_RESERVED7",
	                                                  "NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED",
	                                                  "NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED",
	                                                  "NTLMSSP_NEGOTIATE_ANONYMOUS",
	                                                  "NTLMSSP_RESERVED8",
	                                                  "NTLMSSP_NEGOTIATE_NTLM",
	                                                  "NTLMSSP_RESERVED9",
	                                                  "NTLMSSP_NEGOTIATE_LM_KEY",
	                                                  "NTLMSSP_NEGOTIATE_DATAGRAM",
	                                                  "NTLMSSP_NEGOTIATE_SEAL",
	                                                  "NTLMSSP_NEGOTIATE_SIGN",
	                                                  "NTLMSSP_RESERVED10",
	                                                  "NTLMSSP_REQUEST_TARGET",
	                                                  "NTLMSSP_NEGOTIATE_OEM",
	                                                  "NTLMSSP_NEGOTIATE_UNICODE" };

static void ntlm_print_negotiate_flags(UINT32 flags)
{
	int i;
	const char* str;
	WLog_INFO(TAG, "negotiateFlags \"0x%08" PRIX32 "\"", flags);

	for (i = 31; i >= 0; i--)
	{
		if ((flags >> i) & 1)
		{
			str = NTLM_NEGOTIATE_STRINGS[(31 - i)];
			WLog_INFO(TAG, "\t%s (%d),", str, (31 - i));
		}
	}
}
#endif

static int ntlm_read_message_header(wStream* s, NTLM_MESSAGE_HEADER* header)
{
	if (Stream_GetRemainingLength(s) < 12)
		return -1;

	Stream_Read(s, header->Signature, 8);
	Stream_Read_UINT32(s, header->MessageType);

	if (strncmp((char*)header->Signature, NTLM_SIGNATURE, 8) != 0)
		return -1;

	return 1;
}

static void ntlm_write_message_header(wStream* s, NTLM_MESSAGE_HEADER* header)
{
	Stream_Write(s, header->Signature, sizeof(NTLM_SIGNATURE));
	Stream_Write_UINT32(s, header->MessageType);
}

static void ntlm_populate_message_header(NTLM_MESSAGE_HEADER* header, UINT32 MessageType)
{
	CopyMemory(header->Signature, NTLM_SIGNATURE, sizeof(NTLM_SIGNATURE));
	header->MessageType = MessageType;
}

static int ntlm_read_message_fields(wStream* s, NTLM_MESSAGE_FIELDS* fields)
{
	if (Stream_GetRemainingLength(s) < 8)
		return -1;

	Stream_Read_UINT16(s, fields->Len);          /* Len (2 bytes) */
	Stream_Read_UINT16(s, fields->MaxLen);       /* MaxLen (2 bytes) */
	Stream_Read_UINT32(s, fields->BufferOffset); /* BufferOffset (4 bytes) */
	return 1;
}

static void ntlm_write_message_fields(wStream* s, NTLM_MESSAGE_FIELDS* fields)
{
	if (fields->MaxLen < 1)
		fields->MaxLen = fields->Len;

	Stream_Write_UINT16(s, fields->Len);          /* Len (2 bytes) */
	Stream_Write_UINT16(s, fields->MaxLen);       /* MaxLen (2 bytes) */
	Stream_Write_UINT32(s, fields->BufferOffset); /* BufferOffset (4 bytes) */
}

static int ntlm_read_message_fields_buffer(wStream* s, NTLM_MESSAGE_FIELDS* fields)
{
	if (fields->Len > 0)
	{
		const UINT32 offset = fields->BufferOffset + fields->Len;

		if (fields->BufferOffset > UINT32_MAX - fields->Len)
			return -1;

		if (offset > Stream_Length(s))
			return -1;

		fields->Buffer = (PBYTE)malloc(fields->Len);

		if (!fields->Buffer)
			return -1;

		Stream_SetPosition(s, fields->BufferOffset);
		Stream_Read(s, fields->Buffer, fields->Len);
	}

	return 1;
}

static void ntlm_write_message_fields_buffer(wStream* s, NTLM_MESSAGE_FIELDS* fields)
{
	if (fields->Len > 0)
	{
		Stream_SetPosition(s, fields->BufferOffset);
		Stream_Write(s, fields->Buffer, fields->Len);
	}
}

static void ntlm_free_message_fields_buffer(NTLM_MESSAGE_FIELDS* fields)
{
	if (fields)
	{
		if (fields->Buffer)
		{
			free(fields->Buffer);
			fields->Len = 0;
			fields->MaxLen = 0;
			fields->Buffer = NULL;
			fields->BufferOffset = 0;
		}
	}
}

#ifdef WITH_DEBUG_NTLM
static void ntlm_print_message_fields(NTLM_MESSAGE_FIELDS* fields, const char* name)
{
	WLog_DBG(TAG, "%s (Len: %" PRIu16 " MaxLen: %" PRIu16 " BufferOffset: %" PRIu32 ")", name,
	         fields->Len, fields->MaxLen, fields->BufferOffset);

	if (fields->Len > 0)
		winpr_HexDump(TAG, WLOG_DEBUG, fields->Buffer, fields->Len);
}
#endif

SECURITY_STATUS ntlm_read_NegotiateMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	size_t length;
	NTLM_NEGOTIATE_MESSAGE* message;
	message = &context->NEGOTIATE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_NEGOTIATE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	if (ntlm_read_message_header(s, (NTLM_MESSAGE_HEADER*)message) < 0)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (message->MessageType != MESSAGE_TYPE_NEGOTIATE)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (Stream_GetRemainingLength(s) < 4)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}
	Stream_Read_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */

	if (!((message->NegotiateFlags & NTLMSSP_REQUEST_TARGET) &&
	      (message->NegotiateFlags & NTLMSSP_NEGOTIATE_NTLM) &&
	      (message->NegotiateFlags & NTLMSSP_NEGOTIATE_UNICODE)))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	context->NegotiateFlags = message->NegotiateFlags;

	/* only set if NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED is set */

	if (ntlm_read_message_fields(s, &(message->DomainName)) < 0) /* DomainNameFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	/* only set if NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED is set */

	if (ntlm_read_message_fields(s, &(message->Workstation)) < 0) /* WorkstationFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
	{
		if (ntlm_read_version_info(s, &(message->Version)) < 0) /* Version (8 bytes) */
		{
			Stream_Free(s, FALSE);
			return SEC_E_INVALID_TOKEN;
		}
	}

	length = Stream_GetPosition(s);
	buffer->cbBuffer = length;

	if (!sspi_SecBufferAlloc(&context->NegotiateMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->NegotiateMessage.pvBuffer, buffer->pvBuffer, buffer->cbBuffer);
	context->NegotiateMessage.BufferType = buffer->BufferType;
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "NEGOTIATE_MESSAGE (length = %" PRIu32 ")", context->NegotiateMessage.cbBuffer);
	winpr_HexDump(TAG, WLOG_DEBUG, context->NegotiateMessage.pvBuffer,
	              context->NegotiateMessage.cbBuffer);
	ntlm_print_negotiate_flags(message->NegotiateFlags);

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

#endif
	context->state = NTLM_STATE_CHALLENGE;
	Stream_Free(s, FALSE);
	return SEC_I_CONTINUE_NEEDED;
}

SECURITY_STATUS ntlm_write_NegotiateMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	size_t length;
	NTLM_NEGOTIATE_MESSAGE* message;
	message = &context->NEGOTIATE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_NEGOTIATE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	ntlm_populate_message_header((NTLM_MESSAGE_HEADER*)message, MESSAGE_TYPE_NEGOTIATE);

	if (context->NTLMv2)
	{
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_56;
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_VERSION;
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_LM_KEY;
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_OEM;
	}

	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_KEY_EXCH;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_128;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_EXTENDED_SESSION_SECURITY;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_ALWAYS_SIGN;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_NTLM;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_SIGN;
	message->NegotiateFlags |= NTLMSSP_REQUEST_TARGET;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_UNICODE;

	if (context->confidentiality)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_SEAL;

	if (context->SendVersionInfo)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_VERSION;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_get_version_info(&(message->Version));

	context->NegotiateFlags = message->NegotiateFlags;
	/* Message Header (12 bytes) */
	ntlm_write_message_header(s, (NTLM_MESSAGE_HEADER*)message);
	Stream_Write_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */
	/* only set if NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED is set */
	/* DomainNameFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->DomainName));
	/* only set if NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED is set */
	/* WorkstationFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->Workstation));

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_write_version_info(s, &(message->Version));

	length = Stream_GetPosition(s);
	buffer->cbBuffer = length;

	if (!sspi_SecBufferAlloc(&context->NegotiateMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->NegotiateMessage.pvBuffer, buffer->pvBuffer, buffer->cbBuffer);
	context->NegotiateMessage.BufferType = buffer->BufferType;
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "NEGOTIATE_MESSAGE (length = %d)", length);
	winpr_HexDump(TAG, WLOG_DEBUG, Stream_Buffer(s), length);

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

#endif
	context->state = NTLM_STATE_CHALLENGE;
	Stream_Free(s, FALSE);
	return SEC_I_CONTINUE_NEEDED;
}

SECURITY_STATUS ntlm_read_ChallengeMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	int length;
	PBYTE StartOffset;
	PBYTE PayloadOffset;
	NTLM_AV_PAIR* AvTimestamp;
	NTLM_CHALLENGE_MESSAGE* message;
	ntlm_generate_client_challenge(context);
	message = &context->CHALLENGE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_CHALLENGE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	StartOffset = Stream_Pointer(s);

	if (ntlm_read_message_header(s, (NTLM_MESSAGE_HEADER*)message) < 0)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (message->MessageType != MESSAGE_TYPE_CHALLENGE)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->TargetName)) < 0) /* TargetNameFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (Stream_GetRemainingLength(s) < 4)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	Stream_Read_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */
	context->NegotiateFlags = message->NegotiateFlags;

	if (Stream_GetRemainingLength(s) < 8)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	Stream_Read(s, message->ServerChallenge, 8); /* ServerChallenge (8 bytes) */
	CopyMemory(context->ServerChallenge, message->ServerChallenge, 8);

	if (Stream_GetRemainingLength(s) < 8)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	Stream_Read(s, message->Reserved, 8); /* Reserved (8 bytes), should be ignored */

	if (ntlm_read_message_fields(s, &(message->TargetInfo)) < 0) /* TargetInfoFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (context->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
	{
		if (ntlm_read_version_info(s, &(message->Version)) < 0) /* Version (8 bytes) */
		{
			Stream_Free(s, FALSE);
			return SEC_E_INVALID_TOKEN;
		}
	}

	/* Payload (variable) */
	PayloadOffset = Stream_Pointer(s);

	if (message->TargetName.Len > 0)
	{
		if (ntlm_read_message_fields_buffer(s, &(message->TargetName)) < 0)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}
	}

	if (message->TargetInfo.Len > 0)
	{
		size_t cbAvTimestamp;

		if (ntlm_read_message_fields_buffer(s, &(message->TargetInfo)) < 0)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}

		context->ChallengeTargetInfo.pvBuffer = message->TargetInfo.Buffer;
		context->ChallengeTargetInfo.cbBuffer = message->TargetInfo.Len;
		AvTimestamp = ntlm_av_pair_get((NTLM_AV_PAIR*)message->TargetInfo.Buffer,
		                               message->TargetInfo.Len, MsvAvTimestamp, &cbAvTimestamp);

		if (AvTimestamp)
		{
			PBYTE ptr = ntlm_av_pair_get_value_pointer(AvTimestamp);

			if (!ptr)
				return SEC_E_INTERNAL_ERROR;

			if (context->NTLMv2)
				context->UseMIC = TRUE;

			CopyMemory(context->ChallengeTimestamp, ptr, 8);
		}
	}

	length = (PayloadOffset - StartOffset) + message->TargetName.Len + message->TargetInfo.Len;

	if (!sspi_SecBufferAlloc(&context->ChallengeMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->ChallengeMessage.pvBuffer, StartOffset, length);
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "CHALLENGE_MESSAGE (length = %d)", length);
	winpr_HexDump(TAG, WLOG_DEBUG, context->ChallengeMessage.pvBuffer,
	              context->ChallengeMessage.cbBuffer);
	ntlm_print_negotiate_flags(context->NegotiateFlags);

	if (context->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

	ntlm_print_message_fields(&(message->TargetName), "TargetName");
	ntlm_print_message_fields(&(message->TargetInfo), "TargetInfo");

	if (context->ChallengeTargetInfo.cbBuffer > 0)
	{
		WLog_DBG(TAG, "ChallengeTargetInfo (%" PRIu32 "):", context->ChallengeTargetInfo.cbBuffer);
		ntlm_print_av_pair_list(context->ChallengeTargetInfo.pvBuffer,
		                        context->ChallengeTargetInfo.cbBuffer);
	}

#endif
	/* AV_PAIRs */

	if (context->NTLMv2)
	{
		if (ntlm_construct_authenticate_target_info(context) < 0)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}

		sspi_SecBufferFree(&context->ChallengeTargetInfo);
		context->ChallengeTargetInfo.pvBuffer = context->AuthenticateTargetInfo.pvBuffer;
		context->ChallengeTargetInfo.cbBuffer = context->AuthenticateTargetInfo.cbBuffer;
	}

	ntlm_generate_timestamp(context); /* Timestamp */

	if (ntlm_compute_lm_v2_response(context) < 0) /* LmChallengeResponse */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (ntlm_compute_ntlm_v2_response(context) < 0) /* NtChallengeResponse */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	ntlm_generate_key_exchange_key(context);     /* KeyExchangeKey */
	ntlm_generate_random_session_key(context);   /* RandomSessionKey */
	ntlm_generate_exported_session_key(context); /* ExportedSessionKey */
	ntlm_encrypt_random_session_key(context);    /* EncryptedRandomSessionKey */
	/* Generate signing keys */
	ntlm_generate_client_signing_key(context);
	ntlm_generate_server_signing_key(context);
	/* Generate sealing keys */
	ntlm_generate_client_sealing_key(context);
	ntlm_generate_server_sealing_key(context);
	/* Initialize RC4 seal state using client sealing key */
	ntlm_init_rc4_seal_states(context);
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "ClientChallenge");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientChallenge, 8);
	WLog_DBG(TAG, "ServerChallenge");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerChallenge, 8);
	WLog_DBG(TAG, "SessionBaseKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->SessionBaseKey, 16);
	WLog_DBG(TAG, "KeyExchangeKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->KeyExchangeKey, 16);
	WLog_DBG(TAG, "ExportedSessionKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ExportedSessionKey, 16);
	WLog_DBG(TAG, "RandomSessionKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->RandomSessionKey, 16);
	WLog_DBG(TAG, "ClientSigningKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientSigningKey, 16);
	WLog_DBG(TAG, "ClientSealingKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientSealingKey, 16);
	WLog_DBG(TAG, "ServerSigningKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerSigningKey, 16);
	WLog_DBG(TAG, "ServerSealingKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerSealingKey, 16);
	WLog_DBG(TAG, "Timestamp");
	winpr_HexDump(TAG, WLOG_DEBUG, context->Timestamp, 8);
#endif
	context->state = NTLM_STATE_AUTHENTICATE;
	ntlm_free_message_fields_buffer(&(message->TargetName));
	Stream_Free(s, FALSE);
	return SEC_I_CONTINUE_NEEDED;
}

SECURITY_STATUS ntlm_write_ChallengeMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	size_t length;
	UINT32 PayloadOffset;
	NTLM_CHALLENGE_MESSAGE* message;
	message = &context->CHALLENGE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_CHALLENGE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	ntlm_get_version_info(&(message->Version)); /* Version */
	ntlm_generate_server_challenge(context);    /* Server Challenge */
	ntlm_generate_timestamp(context);           /* Timestamp */

	if (ntlm_construct_challenge_target_info(context) < 0) /* TargetInfo */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(message->ServerChallenge, context->ServerChallenge, 8); /* ServerChallenge */
	message->NegotiateFlags = context->NegotiateFlags;
	ntlm_populate_message_header((NTLM_MESSAGE_HEADER*)message, MESSAGE_TYPE_CHALLENGE);
	/* Message Header (12 bytes) */
	ntlm_write_message_header(s, (NTLM_MESSAGE_HEADER*)message);

	if (message->NegotiateFlags & NTLMSSP_REQUEST_TARGET)
	{
		message->TargetName.Len = (UINT16)context->TargetName.cbBuffer;
		message->TargetName.Buffer = (PBYTE)context->TargetName.pvBuffer;
	}

	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_TARGET_INFO;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_TARGET_INFO)
	{
		message->TargetInfo.Len = (UINT16)context->ChallengeTargetInfo.cbBuffer;
		message->TargetInfo.Buffer = (PBYTE)context->ChallengeTargetInfo.pvBuffer;
	}

	PayloadOffset = 48;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		PayloadOffset += 8;

	message->TargetName.BufferOffset = PayloadOffset;
	message->TargetInfo.BufferOffset = message->TargetName.BufferOffset + message->TargetName.Len;
	/* TargetNameFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->TargetName));
	Stream_Write_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */
	Stream_Write(s, message->ServerChallenge, 8);    /* ServerChallenge (8 bytes) */
	Stream_Write(s, message->Reserved, 8);           /* Reserved (8 bytes), should be ignored */
	/* TargetInfoFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->TargetInfo));

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_write_version_info(s, &(message->Version)); /* Version (8 bytes) */

	/* Payload (variable) */

	if (message->NegotiateFlags & NTLMSSP_REQUEST_TARGET)
		ntlm_write_message_fields_buffer(s, &(message->TargetName));

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_TARGET_INFO)
		ntlm_write_message_fields_buffer(s, &(message->TargetInfo));

	length = Stream_GetPosition(s);
	buffer->cbBuffer = length;

	if (!sspi_SecBufferAlloc(&context->ChallengeMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->ChallengeMessage.pvBuffer, Stream_Buffer(s), length);
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "CHALLENGE_MESSAGE (length = %d)", length);
	winpr_HexDump(TAG, WLOG_DEBUG, context->ChallengeMessage.pvBuffer,
	              context->ChallengeMessage.cbBuffer);
	ntlm_print_negotiate_flags(message->NegotiateFlags);

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

	ntlm_print_message_fields(&(message->TargetName), "TargetName");
	ntlm_print_message_fields(&(message->TargetInfo), "TargetInfo");
#endif
	context->state = NTLM_STATE_AUTHENTICATE;
	Stream_Free(s, FALSE);
	return SEC_I_CONTINUE_NEEDED;
}

SECURITY_STATUS ntlm_read_AuthenticateMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	size_t length;
	UINT32 flags;
	NTLM_AV_PAIR* AvFlags;
	UINT32 PayloadBufferOffset;
	NTLM_AUTHENTICATE_MESSAGE* message;
	SSPI_CREDENTIALS* credentials = context->credentials;
	flags = 0;
	AvFlags = NULL;
	message = &context->AUTHENTICATE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_AUTHENTICATE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	if (ntlm_read_message_header(s, (NTLM_MESSAGE_HEADER*)message) < 0)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (message->MessageType != MESSAGE_TYPE_AUTHENTICATE)
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->LmChallengeResponse)) <
	    0) /* LmChallengeResponseFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->NtChallengeResponse)) <
	    0) /* NtChallengeResponseFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->DomainName)) < 0) /* DomainNameFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->UserName)) < 0) /* UserNameFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->Workstation)) < 0) /* WorkstationFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (ntlm_read_message_fields(s, &(message->EncryptedRandomSessionKey)) <
	    0) /* EncryptedRandomSessionKeyFields (8 bytes) */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	Stream_Read_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */
	context->NegotiateKeyExchange =
	    (message->NegotiateFlags & NTLMSSP_NEGOTIATE_KEY_EXCH) ? TRUE : FALSE;

	if ((context->NegotiateKeyExchange && !message->EncryptedRandomSessionKey.Len) ||
	    (!context->NegotiateKeyExchange && message->EncryptedRandomSessionKey.Len))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INVALID_TOKEN;
	}

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
	{
		if (ntlm_read_version_info(s, &(message->Version)) < 0) /* Version (8 bytes) */
		{
			Stream_Free(s, FALSE);
			return SEC_E_INVALID_TOKEN;
		}
	}

	PayloadBufferOffset = Stream_GetPosition(s);

	if (ntlm_read_message_fields_buffer(s, &(message->DomainName)) < 0) /* DomainName */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (ntlm_read_message_fields_buffer(s, &(message->UserName)) < 0) /* UserName */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (ntlm_read_message_fields_buffer(s, &(message->Workstation)) < 0) /* Workstation */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (ntlm_read_message_fields_buffer(s, &(message->LmChallengeResponse)) <
	    0) /* LmChallengeResponse */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (ntlm_read_message_fields_buffer(s, &(message->NtChallengeResponse)) <
	    0) /* NtChallengeResponse */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (message->NtChallengeResponse.Len > 0)
	{
		size_t cbAvFlags;
		wStream* snt =
		    Stream_New(message->NtChallengeResponse.Buffer, message->NtChallengeResponse.Len);

		if (!snt)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}

		if (ntlm_read_ntlm_v2_response(snt, &(context->NTLMv2Response)) < 0)
		{
			Stream_Free(s, FALSE);
			Stream_Free(snt, FALSE);
			return SEC_E_INVALID_TOKEN;
		}

		Stream_Free(snt, FALSE);
		context->NtChallengeResponse.pvBuffer = message->NtChallengeResponse.Buffer;
		context->NtChallengeResponse.cbBuffer = message->NtChallengeResponse.Len;
		sspi_SecBufferFree(&(context->ChallengeTargetInfo));
		context->ChallengeTargetInfo.pvBuffer = (void*)context->NTLMv2Response.Challenge.AvPairs;
		context->ChallengeTargetInfo.cbBuffer = message->NtChallengeResponse.Len - (28 + 16);
		CopyMemory(context->ClientChallenge, context->NTLMv2Response.Challenge.ClientChallenge, 8);
		AvFlags =
		    ntlm_av_pair_get(context->NTLMv2Response.Challenge.AvPairs,
		                     context->NTLMv2Response.Challenge.cbAvPairs, MsvAvFlags, &cbAvFlags);

		if (AvFlags)
			Data_Read_UINT32(ntlm_av_pair_get_value_pointer(AvFlags), flags);
	}

	if (ntlm_read_message_fields_buffer(s, &(message->EncryptedRandomSessionKey)) <
	    0) /* EncryptedRandomSessionKey */
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	if (message->EncryptedRandomSessionKey.Len > 0)
	{
		if (message->EncryptedRandomSessionKey.Len != 16)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INVALID_TOKEN;
		}

		CopyMemory(context->EncryptedRandomSessionKey, message->EncryptedRandomSessionKey.Buffer,
		           16);
	}

	length = Stream_GetPosition(s);

	if (!sspi_SecBufferAlloc(&context->AuthenticateMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->AuthenticateMessage.pvBuffer, Stream_Buffer(s), length);
	buffer->cbBuffer = length;
	Stream_SetPosition(s, PayloadBufferOffset);

	if (flags & MSV_AV_FLAGS_MESSAGE_INTEGRITY_CHECK)
	{
		context->MessageIntegrityCheckOffset = (UINT32)Stream_GetPosition(s);

		if (Stream_GetRemainingLength(s) < 16)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INVALID_TOKEN;
		}

		Stream_Read(s, message->MessageIntegrityCheck, 16);
	}

#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "AUTHENTICATE_MESSAGE (length = %" PRIu32 ")",
	         context->AuthenticateMessage.cbBuffer);
	winpr_HexDump(TAG, WLOG_DEBUG, context->AuthenticateMessage.pvBuffer,
	              context->AuthenticateMessage.cbBuffer);

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

	ntlm_print_message_fields(&(message->DomainName), "DomainName");
	ntlm_print_message_fields(&(message->UserName), "UserName");
	ntlm_print_message_fields(&(message->Workstation), "Workstation");
	ntlm_print_message_fields(&(message->LmChallengeResponse), "LmChallengeResponse");
	ntlm_print_message_fields(&(message->NtChallengeResponse), "NtChallengeResponse");
	ntlm_print_message_fields(&(message->EncryptedRandomSessionKey), "EncryptedRandomSessionKey");
	ntlm_print_av_pair_list(context->NTLMv2Response.Challenge.AvPairs,
	                        context->NTLMv2Response.Challenge.cbAvPairs);

	if (flags & MSV_AV_FLAGS_MESSAGE_INTEGRITY_CHECK)
	{
		WLog_DBG(TAG, "MessageIntegrityCheck:");
		winpr_HexDump(TAG, WLOG_DEBUG, message->MessageIntegrityCheck, 16);
	}

#endif

	if (message->UserName.Len > 0)
	{
		credentials->identity.User = (UINT16*)malloc(message->UserName.Len);

		if (!credentials->identity.User)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}

		CopyMemory(credentials->identity.User, message->UserName.Buffer, message->UserName.Len);
		credentials->identity.UserLength = message->UserName.Len / 2;
	}

	if (message->DomainName.Len > 0)
	{
		credentials->identity.Domain = (UINT16*)malloc(message->DomainName.Len);

		if (!credentials->identity.Domain)
		{
			Stream_Free(s, FALSE);
			return SEC_E_INTERNAL_ERROR;
		}

		CopyMemory(credentials->identity.Domain, message->DomainName.Buffer,
		           message->DomainName.Len);
		credentials->identity.DomainLength = message->DomainName.Len / 2;
	}

	Stream_Free(s, FALSE);
	/* Computations beyond this point require the NTLM hash of the password */
	context->state = NTLM_STATE_COMPLETION;
	return SEC_I_COMPLETE_NEEDED;
}

/**
 * Send NTLMSSP AUTHENTICATE_MESSAGE.\n
 * AUTHENTICATE_MESSAGE @msdn{cc236643}
 * @param NTLM context
 * @param buffer
 */

SECURITY_STATUS ntlm_write_AuthenticateMessage(NTLM_CONTEXT* context, PSecBuffer buffer)
{
	wStream* s;
	size_t length;
	UINT32 PayloadBufferOffset;
	NTLM_AUTHENTICATE_MESSAGE* message;
	SSPI_CREDENTIALS* credentials = context->credentials;
	message = &context->AUTHENTICATE_MESSAGE;
	ZeroMemory(message, sizeof(NTLM_AUTHENTICATE_MESSAGE));
	s = Stream_New((BYTE*)buffer->pvBuffer, buffer->cbBuffer);

	if (!s)
		return SEC_E_INTERNAL_ERROR;

	if (context->NTLMv2)
	{
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_56;

		if (context->SendVersionInfo)
			message->NegotiateFlags |= NTLMSSP_NEGOTIATE_VERSION;
	}

	if (context->UseMIC)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_TARGET_INFO;

	if (context->SendWorkstationName)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED;

	if (context->confidentiality)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_SEAL;

	if (context->CHALLENGE_MESSAGE.NegotiateFlags & NTLMSSP_NEGOTIATE_KEY_EXCH)
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_KEY_EXCH;

	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_128;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_EXTENDED_SESSION_SECURITY;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_ALWAYS_SIGN;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_NTLM;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_SIGN;
	message->NegotiateFlags |= NTLMSSP_REQUEST_TARGET;
	message->NegotiateFlags |= NTLMSSP_NEGOTIATE_UNICODE;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_get_version_info(&(message->Version));

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED)
	{
		message->Workstation.Len = context->Workstation.Length;
		message->Workstation.Buffer = (BYTE*)context->Workstation.Buffer;
	}

	if (credentials->identity.DomainLength > 0)
	{
		message->NegotiateFlags |= NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED;
		message->DomainName.Len = (UINT16)credentials->identity.DomainLength * 2;
		message->DomainName.Buffer = (BYTE*)credentials->identity.Domain;
	}

	message->UserName.Len = (UINT16)credentials->identity.UserLength * 2;
	message->UserName.Buffer = (BYTE*)credentials->identity.User;
	message->LmChallengeResponse.Len = (UINT16)context->LmChallengeResponse.cbBuffer;
	message->LmChallengeResponse.Buffer = (BYTE*)context->LmChallengeResponse.pvBuffer;
	message->NtChallengeResponse.Len = (UINT16)context->NtChallengeResponse.cbBuffer;
	message->NtChallengeResponse.Buffer = (BYTE*)context->NtChallengeResponse.pvBuffer;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_KEY_EXCH)
	{
		message->EncryptedRandomSessionKey.Len = 16;
		message->EncryptedRandomSessionKey.Buffer = context->EncryptedRandomSessionKey;
	}

	PayloadBufferOffset = 64;

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		PayloadBufferOffset += 8; /* Version (8 bytes) */

	if (context->UseMIC)
		PayloadBufferOffset += 16; /* Message Integrity Check (16 bytes) */

	message->DomainName.BufferOffset = PayloadBufferOffset;
	message->UserName.BufferOffset = message->DomainName.BufferOffset + message->DomainName.Len;
	message->Workstation.BufferOffset = message->UserName.BufferOffset + message->UserName.Len;
	message->LmChallengeResponse.BufferOffset =
	    message->Workstation.BufferOffset + message->Workstation.Len;
	message->NtChallengeResponse.BufferOffset =
	    message->LmChallengeResponse.BufferOffset + message->LmChallengeResponse.Len;
	message->EncryptedRandomSessionKey.BufferOffset =
	    message->NtChallengeResponse.BufferOffset + message->NtChallengeResponse.Len;
	ntlm_populate_message_header((NTLM_MESSAGE_HEADER*)message, MESSAGE_TYPE_AUTHENTICATE);
	ntlm_write_message_header(s, (NTLM_MESSAGE_HEADER*)message); /* Message Header (12 bytes) */
	ntlm_write_message_fields(
	    s, &(message->LmChallengeResponse)); /* LmChallengeResponseFields (8 bytes) */
	ntlm_write_message_fields(
	    s, &(message->NtChallengeResponse));               /* NtChallengeResponseFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->DomainName));  /* DomainNameFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->UserName));    /* UserNameFields (8 bytes) */
	ntlm_write_message_fields(s, &(message->Workstation)); /* WorkstationFields (8 bytes) */
	ntlm_write_message_fields(
	    s, &(message->EncryptedRandomSessionKey));   /* EncryptedRandomSessionKeyFields (8 bytes) */
	Stream_Write_UINT32(s, message->NegotiateFlags); /* NegotiateFlags (4 bytes) */

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_write_version_info(s, &(message->Version)); /* Version (8 bytes) */

	if (context->UseMIC)
	{
		context->MessageIntegrityCheckOffset = (UINT32)Stream_GetPosition(s);
		Stream_Zero(s, 16); /* Message Integrity Check (16 bytes) */
	}

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_DOMAIN_SUPPLIED)
		ntlm_write_message_fields_buffer(s, &(message->DomainName)); /* DomainName */

	ntlm_write_message_fields_buffer(s, &(message->UserName)); /* UserName */

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_WORKSTATION_SUPPLIED)
		ntlm_write_message_fields_buffer(s, &(message->Workstation)); /* Workstation */

	ntlm_write_message_fields_buffer(s, &(message->LmChallengeResponse)); /* LmChallengeResponse */
	ntlm_write_message_fields_buffer(s, &(message->NtChallengeResponse)); /* NtChallengeResponse */

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_KEY_EXCH)
		ntlm_write_message_fields_buffer(
		    s, &(message->EncryptedRandomSessionKey)); /* EncryptedRandomSessionKey */

	length = Stream_GetPosition(s);

	if (!sspi_SecBufferAlloc(&context->AuthenticateMessage, length))
	{
		Stream_Free(s, FALSE);
		return SEC_E_INTERNAL_ERROR;
	}

	CopyMemory(context->AuthenticateMessage.pvBuffer, Stream_Buffer(s), length);
	buffer->cbBuffer = length;

	if (context->UseMIC)
	{
		/* Message Integrity Check */
		ntlm_compute_message_integrity_check(context, message->MessageIntegrityCheck, 16);
		Stream_SetPosition(s, context->MessageIntegrityCheckOffset);
		Stream_Write(s, message->MessageIntegrityCheck, 16);
		Stream_SetPosition(s, length);
	}

#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "AUTHENTICATE_MESSAGE (length = %d)", length);
	winpr_HexDump(TAG, WLOG_DEBUG, Stream_Buffer(s), length);
	ntlm_print_negotiate_flags(message->NegotiateFlags);

	if (message->NegotiateFlags & NTLMSSP_NEGOTIATE_VERSION)
		ntlm_print_version_info(&(message->Version));

	if (context->AuthenticateTargetInfo.cbBuffer > 0)
	{
		WLog_DBG(TAG,
		         "AuthenticateTargetInfo (%" PRIu32 "):", context->AuthenticateTargetInfo.cbBuffer);
		ntlm_print_av_pair_list(context->AuthenticateTargetInfo.pvBuffer,
		                        context->AuthenticateTargetInfo.cbBuffer);
	}

	ntlm_print_message_fields(&(message->DomainName), "DomainName");
	ntlm_print_message_fields(&(message->UserName), "UserName");
	ntlm_print_message_fields(&(message->Workstation), "Workstation");
	ntlm_print_message_fields(&(message->LmChallengeResponse), "LmChallengeResponse");
	ntlm_print_message_fields(&(message->NtChallengeResponse), "NtChallengeResponse");
	ntlm_print_message_fields(&(message->EncryptedRandomSessionKey), "EncryptedRandomSessionKey");

	if (context->UseMIC)
	{
		WLog_DBG(TAG, "MessageIntegrityCheck (length = 16)");
		winpr_HexDump(TAG, WLOG_DEBUG, message->MessageIntegrityCheck, 16);
	}

#endif
	context->state = NTLM_STATE_FINAL;
	Stream_Free(s, FALSE);
	return SEC_I_COMPLETE_NEEDED;
}

SECURITY_STATUS ntlm_server_AuthenticateComplete(NTLM_CONTEXT* context)
{
	UINT32 flags = 0;
	size_t cbAvFlags;
	NTLM_AV_PAIR* AvFlags = NULL;
	NTLM_AUTHENTICATE_MESSAGE* message;
	BYTE messageIntegrityCheck[16];

	if (!context)
		return SEC_E_INVALID_PARAMETER;

	if (context->state != NTLM_STATE_COMPLETION)
		return SEC_E_OUT_OF_SEQUENCE;

	message = &context->AUTHENTICATE_MESSAGE;
	AvFlags = ntlm_av_pair_get(context->NTLMv2Response.Challenge.AvPairs,
	                           context->NTLMv2Response.Challenge.cbAvPairs, MsvAvFlags, &cbAvFlags);

	if (AvFlags)
		Data_Read_UINT32(ntlm_av_pair_get_value_pointer(AvFlags), flags);

	if (ntlm_compute_lm_v2_response(context) < 0) /* LmChallengeResponse */
		return SEC_E_INTERNAL_ERROR;

	if (ntlm_compute_ntlm_v2_response(context) < 0) /* NtChallengeResponse */
		return SEC_E_INTERNAL_ERROR;

	/* KeyExchangeKey */
	ntlm_generate_key_exchange_key(context);
	/* EncryptedRandomSessionKey */
	ntlm_decrypt_random_session_key(context);
	/* ExportedSessionKey */
	ntlm_generate_exported_session_key(context);

	if (flags & MSV_AV_FLAGS_MESSAGE_INTEGRITY_CHECK)
	{
		ZeroMemory(
		    &((PBYTE)context->AuthenticateMessage.pvBuffer)[context->MessageIntegrityCheckOffset],
		    16);
		ntlm_compute_message_integrity_check(context, messageIntegrityCheck,
		                                     sizeof(messageIntegrityCheck));
		CopyMemory(
		    &((PBYTE)context->AuthenticateMessage.pvBuffer)[context->MessageIntegrityCheckOffset],
		    message->MessageIntegrityCheck, 16);

		if (memcmp(messageIntegrityCheck, message->MessageIntegrityCheck, 16) != 0)
		{
			WLog_ERR(TAG, "Message Integrity Check (MIC) verification failed!");
#ifdef WITH_DEBUG_NTLM
			WLog_ERR(TAG, "Expected MIC:");
			winpr_HexDump(TAG, WLOG_ERROR, messageIntegrityCheck, sizeof(messageIntegrityCheck));
			WLog_ERR(TAG, "Actual MIC:");
			winpr_HexDump(TAG, WLOG_ERROR, message->MessageIntegrityCheck,
			              sizeof(message->MessageIntegrityCheck));
#endif
			return SEC_E_MESSAGE_ALTERED;
		}
	}
	else
	{
		/* no mic message was present

		   https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-nlmp/f9e6fbc4-a953-4f24-b229-ccdcc213b9ec
		   the mic is optional, as not supported in Windows NT, Windows 2000, Windows XP, and
		   Windows Server 2003 and, as it seems, in the NTLMv2 implementation of Qt5.

		   now check the NtProofString, to detect if the entered client password matches the
		   expected password.
		   */

#ifdef WITH_DEBUG_NTLM
		WLog_DBG(TAG, "No MIC present, using NtProofString for verification.");
#endif

		if (memcmp(context->NTLMv2Response.Response, context->NtProofString, 16) != 0)
		{
			WLog_ERR(TAG, "NtProofString verification failed!");
#ifdef WITH_DEBUG_NTLM
			WLog_ERR(TAG, "Expected NtProofString:");
			winpr_HexDump(TAG, WLOG_ERROR, context->NtProofString, sizeof(context->NtProofString));
			WLog_ERR(TAG, "Actual NtProofString:");
			winpr_HexDump(TAG, WLOG_ERROR, context->NTLMv2Response.Response,
			              sizeof(context->NTLMv2Response));
#endif
			return SEC_E_LOGON_DENIED;
		}
	}

	/* Generate signing keys */
	ntlm_generate_client_signing_key(context);
	ntlm_generate_server_signing_key(context);
	/* Generate sealing keys */
	ntlm_generate_client_sealing_key(context);
	ntlm_generate_server_sealing_key(context);
	/* Initialize RC4 seal state */
	ntlm_init_rc4_seal_states(context);
#ifdef WITH_DEBUG_NTLM
	WLog_DBG(TAG, "ClientChallenge");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientChallenge, 8);
	WLog_DBG(TAG, "ServerChallenge");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerChallenge, 8);
	WLog_DBG(TAG, "SessionBaseKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->SessionBaseKey, 16);
	WLog_DBG(TAG, "KeyExchangeKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->KeyExchangeKey, 16);
	WLog_DBG(TAG, "ExportedSessionKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ExportedSessionKey, 16);
	WLog_DBG(TAG, "RandomSessionKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->RandomSessionKey, 16);
	WLog_DBG(TAG, "ClientSigningKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientSigningKey, 16);
	WLog_DBG(TAG, "ClientSealingKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ClientSealingKey, 16);
	WLog_DBG(TAG, "ServerSigningKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerSigningKey, 16);
	WLog_DBG(TAG, "ServerSealingKey");
	winpr_HexDump(TAG, WLOG_DEBUG, context->ServerSealingKey, 16);
	WLog_DBG(TAG, "Timestamp");
	winpr_HexDump(TAG, WLOG_DEBUG, context->Timestamp, 8);
#endif
	context->state = NTLM_STATE_FINAL;
	ntlm_free_message_fields_buffer(&(message->DomainName));
	ntlm_free_message_fields_buffer(&(message->UserName));
	ntlm_free_message_fields_buffer(&(message->Workstation));
	ntlm_free_message_fields_buffer(&(message->LmChallengeResponse));
	ntlm_free_message_fields_buffer(&(message->NtChallengeResponse));
	ntlm_free_message_fields_buffer(&(message->EncryptedRandomSessionKey));
	return SEC_E_OK;
}