Exemple #1
0
        /// <summary>
        /// Compress SMB2 packet.
        /// </summary>
        /// <param name="packet">The SMB2 packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <returns>The compressed packet, or original packet if compression is not applicable.</returns>
        public static Smb2Packet Compress(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            Smb2Packet compressed;

            if (compressionInfo.SupportChainedCompression)
            {
                compressed = CompressForChained(packet, compressionInfo, role);
            }
            else
            {
                compressed = CompressForNonChained(packet, compressionInfo, role);
            }

            if (compressed == packet)
            {
                // Compression is not applicable.
                return(packet);
            }

            var originalBytes = packet.ToBytes();

            var compressedBytes = compressed.ToBytes();

            // Check whether compression shrinks the on-wire packet size
            if (compressedBytes.Length < originalBytes.Length)
            {
                return(compressed);
            }
            else
            {
                return(packet);
            }
        }
Exemple #2
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        /// <summary>
        /// Decompress the Smb2CompressedPacket.
        /// </summary>
        /// <param name="packet">The compressed packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <returns>Byte array containing the decompressed packet.</returns>
        public static byte[] Decompress(Smb2CompressedPacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool isChained = packet.Header.Flags.HasFlag(Compression_Transform_Header_Flags.SMB2_COMPRESSION_FLAG_CHAINED);

            byte[] decompressedData;
            int    uncompressedDataSize = 0;

            if (isChained)
            {
                decompressedData = DecompressForChained(packet, compressionInfo, role);
            }
            else
            {
                decompressedData = DecompressForNonChained(packet, compressionInfo, role);
                var p = packet as Smb2NonChainedCompressedPacket;
                uncompressedDataSize = p.UncompressedData.Length;
            }

            // If the packed is not chained, the length of UncompressedData may not be 0.
            if (decompressedData.Length != packet.Header.OriginalCompressedSegmentSize + uncompressedDataSize)
            {
                throw new InvalidOperationException($"The length of decompressed data ({decompressedData.Length}) is inconsistent with the sum of compression header length ({packet.Header.OriginalCompressedSegmentSize}) and UncompressedData length ({uncompressedDataSize}).");
            }

            return(decompressedData);
        }
        private static Smb2Packet CompressForChained(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool needCompression = IsCompressionNeeded(packet, compressionInfo, role);

            if (!needCompression)
            {
                return(packet);
            }

            bool isPatternV1Supported = compressionInfo.CompressionIds.Contains(CompressionAlgorithm.Pattern_V1);

            Smb2Packet compressed;

            if (isPatternV1Supported)
            {
                compressed = CompressWithPatternV1(packet, compressionInfo, role);
            }
            else
            {
                // Regress to non-chained since pattern scanning algorithm is not supported.
                compressed = CompressForNonChained(packet, compressionInfo, role);
            }

            return(compressed);
        }
Exemple #4
0
        /// <summary>
        /// Compress SMB2 packet.
        /// </summary>
        /// <param name="packet">The SMB2 packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <param name="offset">The offset where compression start, default zero.</param>
        /// <returns></returns>
        public static Smb2Packet Compress(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role, uint offset = 0)
        {
            var compressionAlgorithm = GetCompressionAlgorithm(packet, compressionInfo, role);

            if (compressionAlgorithm == CompressionAlgorithm.NONE)
            {
                return packet;
            }

            var packetBytes = packet.ToBytes();

            var compressor = GetCompressor(compressionAlgorithm);

            var compressedPacket = new Smb2CompressedPacket();
            compressedPacket.Header.ProtocolId = Smb2Consts.ProtocolIdInCompressionTransformHeader;
            compressedPacket.Header.OriginalCompressedSegmentSize = (uint)packetBytes.Length;
            compressedPacket.Header.CompressionAlgorithm = compressionAlgorithm;
            compressedPacket.Header.Reserved = 0;
            compressedPacket.Header.Offset = offset;
            compressedPacket.UncompressedData = packetBytes.Take((int)offset).ToArray();
            compressedPacket.CompressedData = compressor.Compress(packetBytes.Skip((int)offset).ToArray());

            var compressedPackectBytes = compressedPacket.ToBytes();

            // Check whether compression shrinks the on-wire packet size
            if (compressedPackectBytes.Length < packetBytes.Length)
            {
                compressedPacket.OriginalPacket = packet;
                return compressedPacket;
            }
            else
            {
                return packet;
            }
        }
Exemple #5
0
        private static bool IsCompressionNeeded(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool supportCompression = compressionInfo.CompressionIds.Any(compressionAlgorithm => compressionAlgorithm != CompressionAlgorithm.NONE);

            if (!supportCompression)
            {
                return(false);
            }

            bool needCompression = false;

            switch (role)
            {
            case Smb2Role.Client:
            {
                // Client will compress outgoing packets when:
                // 1. EligibleForCompression is set for write request. (when user hopes write request to be compressed)
                // 2. CompressAllPackets is set. (when user hopes all request to be compressed)
                if (compressionInfo.CompressAllPackets)
                {
                    needCompression = true;
                }
                else if (packet is Smb2WriteRequestPacket)
                {
                    needCompression = packet.EligibleForCompression;
                }
            }
            break;

            case Smb2Role.Server:
            {
                // Server will compress outgoing packets when:
                // 1. CompressAllPackets is set and EligibleForCompression. (when server hopes all responses to be compressed, and request is compressed)
                // 2. EligibleForCompression is set for read response.  (when compress read is specified in read request)
                if (compressionInfo.CompressAllPackets || packet is Smb2ReadResponsePacket)
                {
                    needCompression = packet.EligibleForCompression;
                }
            }
            break;

            default:
            {
                throw new InvalidOperationException("Unknown SMB2 role!");
            }
            }

            if (needCompression && compressionInfo.CompressBufferOnly)
            {
                // Not compress packet if it does not contain buffer.
                if (!(packet is IPacketBuffer) || (packet as IPacketBuffer).BufferLength == 0)
                {
                    needCompression = false;
                }
            }

            return(needCompression);
        }
        private static byte[] DecompressForChained(Smb2CompressedPacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            var p = packet as Smb2ChainedCompressedPacket;

            var result = p.Payloads.SelectMany(tuple =>
            {
                var payloadHeader = tuple.Item1;

                switch (payloadHeader.CompressionAlgorithm)
                {
                case CompressionAlgorithm.NONE:
                    {
                        return(tuple.Item2 as byte[]);
                    }
                    break;

                case CompressionAlgorithm.LZNT1:
                case CompressionAlgorithm.LZ77:
                case CompressionAlgorithm.LZ77Huffman:
                    {
                        var decompressor = GetDecompressor(payloadHeader.CompressionAlgorithm);

                        var decompressedData = decompressor.Decompress(tuple.Item2 as byte[]);

                        if (decompressedData.Length != payloadHeader.OriginalPayloadSize)
                        {
                            throw new InvalidOperationException("The length decompressed chained payload is inconsistent with OriginalPayloadSize of payload header.");
                        }

                        return(decompressedData);
                    }
                    break;

                case CompressionAlgorithm.Pattern_V1:
                    {
                        var pattern = (SMB2_COMPRESSION_PATTERN_PAYLOAD_V1)tuple.Item2;

                        return(Enumerable.Repeat(pattern.Pattern, (int)pattern.Repetitions).ToArray());
                    }
                    break;

                default:
                    {
                        throw new InvalidOperationException("Unexpected compression algorithm!");
                    }
                    break;
                }
            });

            return(result.ToArray());
        }
Exemple #7
0
        /// <summary>
        /// Compress SMB2 packet.
        /// </summary>
        /// <param name="packet">The SMB2 packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <param name="offset">The offset where compression start, default zero.</param>
        /// <returns></returns>
        public static Smb2Packet Compress(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role, uint offset = 0)
        {
            var compressionAlgorithm = GetCompressionAlgorithm(packet, compressionInfo, role);

            if (compressionAlgorithm == CompressionAlgorithm.NONE)
            {
                return(packet);
            }

            var packetBytes = packet.ToBytes();

            var compressor = GetCompressor(compressionAlgorithm);

            var compressedPacket = new Smb2CompressedPacket();

            compressedPacket.Header.ProtocolId = Smb2Consts.ProtocolIdInCompressionTransformHeader;
            compressedPacket.Header.OriginalCompressedSegmentSize = (uint)packetBytes.Length;
            compressedPacket.Header.CompressionAlgorithm          = compressionAlgorithm;
            compressedPacket.Header.Reserved  = 0;
            compressedPacket.Header.Offset    = offset;
            compressedPacket.UncompressedData = packetBytes.Take((int)offset).ToArray();
            compressedPacket.CompressedData   = compressor.Compress(packetBytes.Skip((int)offset).ToArray());

            // HACK: fake size
            if (((Smb2SinglePacket)packet).Header.Command == Smb2Command.WRITE)
            {
                ((Smb2WriteRequestPacket)packet).PayLoad.Length       += 0x1000;
                compressedPacket.Header.OriginalCompressedSegmentSize += 0x1000;
            }

            // HACK: force compressed packet to be sent
            return(compressedPacket);

            // var compressedPackectBytes = compressedPacket.ToBytes();

            // Check whether compression shrinks the on-wire packet size
            // if (compressedPackectBytes.Length < packetBytes.Length)
            // {
            //     compressedPacket.OriginalPacket = packet;
            //     return compressedPacket;
            // }
            // else
            // {
            //     return packet;
            // }
        }
Exemple #8
0
        /// <summary>
        /// Decompress the Smb2CompressedPacket.
        /// </summary>
        /// <param name="packet">The compressed packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <returns>Byte array containing the decompressed packet.</returns>
        public static byte[] Decompress(Smb2CompressedPacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            if (packet.Header.CompressionAlgorithm == CompressionAlgorithm.NONE)
            {
                throw new InvalidOperationException("Invalid CompressionAlgorithm in header!");
            }

            if (!compressionInfo.CompressionIds.Any(compressionAlgorithm => compressionAlgorithm == packet.Header.CompressionAlgorithm))
            {
                throw new InvalidOperationException("The CompressionAlgorithm is not supported!");
            }

            var decompressor = GetDecompressor(packet.Header.CompressionAlgorithm);

            var decompressedBytes = decompressor.Decompress(packet.CompressedData);

            var originalPacketBytes = packet.UncompressedData.Concat(decompressedBytes).ToArray();

            return(originalPacketBytes);
        }
        /// <summary>
        /// Decompress the Smb2CompressedPacket.
        /// </summary>
        /// <param name="packet">The compressed packet.</param>
        /// <param name="compressionInfo">Compression info.</param>
        /// <param name="role">SMB2 role.</param>
        /// <returns>Byte array containing the decompressed packet.</returns>
        public static byte[] Decompress(Smb2CompressedPacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool isChained = packet.Header.Flags.HasFlag(Compression_Transform_Header_Flags.SMB2_COMPRESSION_FLAG_CHAINED);

            byte[] decompressedData;

            if (isChained)
            {
                decompressedData = DecompressForChained(packet, compressionInfo, role);
            }
            else
            {
                decompressedData = DecompressForNonChained(packet, compressionInfo, role);
            }

            if (decompressedData.Length != packet.Header.OriginalCompressedSegmentSize)
            {
                throw new InvalidOperationException($"The length of decompressed data (0x{decompressedData.Length:X08}) is inconsistent with compression header (0x{packet.Header.OriginalCompressedSegmentSize:X08}).");
            }

            return(decompressedData);
        }
Exemple #10
0
        private static CompressionAlgorithm GetPreferredCompressionAlgorithm(Smb2CompressionInfo compressionInfo)
        {
            if (compressionInfo.PreferredCompressionAlgorithm == CompressionAlgorithm.NONE)
            {
                var commonSupportedCompressionAlgorithms = Smb2Utility.GetSupportedCompressionAlgorithms(compressionInfo.CompressionIds);

                if (commonSupportedCompressionAlgorithms.Length > 0)
                {
                    return(commonSupportedCompressionAlgorithms.First());
                }
                else
                {
                    return(CompressionAlgorithm.NONE);
                }
            }
            else
            {
                if (!compressionInfo.CompressionIds.Contains(compressionInfo.PreferredCompressionAlgorithm))
                {
                    throw new InvalidOperationException("Specified preferred compression algorithm is not supported by SUT!");
                }
                return(compressionInfo.PreferredCompressionAlgorithm);
            }
        }
        /// <summary>
        /// Sign, compress and encrypt for Single or Compound packet.
        /// </summary>
        public static Smb2Packet SignCompressAndEncrypt(Smb2Packet originalPacket, Dictionary <ulong, Smb2CryptoInfo> cryptoInfoTable, Smb2CompressionInfo compressioninfo, Smb2Role role)
        {
            ulong sessionId;
            bool  isCompound        = false;
            bool  notEncryptNotSign = false;
            bool  notEncrypt        = false;
            var   compressedPacket  = originalPacket;

            if (originalPacket is Smb2SinglePacket)
            {
                Smb2SinglePacket singlePacket = originalPacket as Smb2SinglePacket;
                sessionId = singlePacket.Header.SessionId;
                // [MS-SMB2] Section 3.2.4.1.8, the request being sent is SMB2 NEGOTIATE,
                // or the request being sent is SMB2 SESSION_SETUP with the SMB2_SESSION_FLAG_BINDING bit set in the Flags field,
                // the client MUST NOT encrypt the message
                if (sessionId == 0 ||
                    (singlePacket.Header.Command == Smb2Command.NEGOTIATE && (singlePacket is Smb2NegotiateRequestPacket)))
                {
                    notEncryptNotSign = true;
                }
                else if ((singlePacket.Header.Command == Smb2Command.SESSION_SETUP && (singlePacket is Smb2SessionSetupRequestPacket) &&
                          (singlePacket as Smb2SessionSetupRequestPacket).PayLoad.Flags == SESSION_SETUP_Request_Flags.SESSION_FLAG_BINDING))
                {
                    notEncrypt = true;
                }
            }
            else if (originalPacket is Smb2CompoundPacket)
            {
                isCompound = true;
                // The subsequent request in compound packet should use the SessionId of the first request for encryption
                sessionId = (originalPacket as Smb2CompoundPacket).Packets[0].Header.SessionId;
            }
            else
            {
                throw new NotImplementedException(string.Format("Signing and encryption are not implemented for packet: {0}", originalPacket.ToString()));
            }

            if (sessionId == 0 || notEncryptNotSign || !cryptoInfoTable.ContainsKey(sessionId))
            {
                if (originalPacket is Smb2CompressiblePacket)
                {
                    compressedPacket = Smb2Compression.Compress(originalPacket as Smb2CompressiblePacket, compressioninfo, role);
                }
                return(compressedPacket);
            }

            Smb2CryptoInfo cryptoInfo = cryptoInfoTable[sessionId];

            #region Encrypt
            // Try to encrypt the message whenever the encryption is supported or not except for sesstion setup.
            // If it's not supported, do it for negative test.
            // For compound packet, the encryption is done for the entire message.
            if (!notEncrypt)
            {
                if (originalPacket is Smb2CompressiblePacket)
                {
                    compressedPacket = Smb2Compression.Compress(originalPacket as Smb2CompressiblePacket, compressioninfo, role);
                }
                var encryptedPacket = Encrypt(sessionId, cryptoInfo, role, compressedPacket, originalPacket);
                if (encryptedPacket != null)
                {
                    return(encryptedPacket);
                }
            }
            #endregion

            #region Sign
            if (cryptoInfo.EnableSessionSigning)
            {
                if (isCompound)
                {
                    // Calculate signature for every packet in the chain
                    foreach (Smb2SinglePacket packet in (originalPacket as Smb2CompoundPacket).Packets)
                    {
                        // If the packet is the first one in the chain or the unralated one, use its own SessionId for sign and encrypt
                        // If it's not the first one and it's the related one, use the SessionId of the first request for sign and encrypt
                        if (!packet.Header.Flags.HasFlag(Packet_Header_Flags_Values.FLAGS_RELATED_OPERATIONS))
                        {
                            sessionId  = packet.Header.SessionId;
                            cryptoInfo = cryptoInfoTable[sessionId];
                        }

                        packet.Header.Signature = Sign(cryptoInfo, packet.ToBytes());
                    }
                }
                else
                {
                    (originalPacket as Smb2SinglePacket).Header.Signature = Sign(cryptoInfo, originalPacket.ToBytes());
                }
            }
            #endregion
            if (originalPacket is Smb2CompressiblePacket)
            {
                compressedPacket = Smb2Compression.Compress(originalPacket as Smb2CompressiblePacket, compressioninfo, role);
            }
            return(compressedPacket);
        }
Exemple #12
0
        private static CompressionAlgorithm GetCompressionAlgorithm(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool supportCompression = compressionInfo.CompressionIds.Any(compressionAlgorithm => compressionAlgorithm != CompressionAlgorithm.NONE);

            if (!supportCompression)
            {
                return(CompressionAlgorithm.NONE);
            }

            bool needCompression = false;

            switch (role)
            {
            case Smb2Role.Client:
            {
                // Client will compress outgoing packets when:
                // 1. EligibleForCompression is set for write request. (when user hopes write request to be compressed)
                // 2. CompressAllPackets is set. (when user hopes all request to be compressed)
                if (compressionInfo.CompressAllPackets)
                {
                    needCompression = true;
                }
                else if (packet is Smb2WriteRequestPacket)
                {
                    needCompression = packet.EligibleForCompression;
                }
            }
            break;

            case Smb2Role.Server:
            {
                // Server will compress outgoing packets when:
                // 1. CompressAllPackets is set and EligibleForCompression. (when server hopes all responses to be compressed, and request is compressed)
                // 2. EligibleForCompression is set for read response.  (when compress read is specified in read request)
                if (compressionInfo.CompressAllPackets || packet is Smb2ReadResponsePacket)
                {
                    needCompression = packet.EligibleForCompression;
                }
            }
            break;

            default:
            {
                throw new InvalidOperationException("Unknown SMB2 role!");
            }
            }

            if (!needCompression)
            {
                return(CompressionAlgorithm.NONE);
            }

            if (compressionInfo.PreferredCompressionAlgorithm == CompressionAlgorithm.NONE)
            {
                return(compressionInfo.CompressionIds.First(compressionAlgorithm => compressionAlgorithm != CompressionAlgorithm.NONE));
            }
            else
            {
                if (!compressionInfo.CompressionIds.Contains(compressionInfo.PreferredCompressionAlgorithm))
                {
                    throw new InvalidOperationException("Specified preferred compression algorithm is not supported by SUT!");
                }
                return(compressionInfo.PreferredCompressionAlgorithm);
            }
        }
Exemple #13
0
        private static CompressionAlgorithm GetCompressionAlgorithm(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            bool needCompression = IsCompressionNeeded(packet, compressionInfo, role);

            if (!needCompression)
            {
                return(CompressionAlgorithm.NONE);
            }

            var result = GetPreferredCompressionAlgorithm(compressionInfo);

            return(result);
        }
Exemple #14
0
        private static Smb2Packet CompressForNonChained(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            var compressionAlgorithm = GetCompressionAlgorithm(packet, compressionInfo, role);

            if (compressionAlgorithm == CompressionAlgorithm.NONE)
            {
                return(packet);
            }

            var packetBytes = packet.ToBytes();

            var compressor = GetCompressor(compressionAlgorithm);

            uint offset = 0;

            if (compressionInfo.CompressBufferOnly)
            {
                offset = (packet as IPacketBuffer).BufferOffset;
            }

            var compressedPacket = new Smb2NonChainedCompressedPacket();

            compressedPacket.Header.ProtocolId = Smb2Consts.ProtocolIdInCompressionTransformHeader;
            compressedPacket.Header.OriginalCompressedSegmentSize = (uint)packetBytes.Length;
            compressedPacket.Header.CompressionAlgorithm          = compressionAlgorithm;
            compressedPacket.Header.Flags     = Compression_Transform_Header_Flags.SMB2_COMPRESSION_FLAG_NONE;
            compressedPacket.Header.Offset    = offset;
            compressedPacket.UncompressedData = packetBytes.Take((int)offset).ToArray();
            compressedPacket.CompressedData   = compressor.Compress(packetBytes.Skip((int)offset).ToArray());

            compressedPacket.OriginalPacket = packet;

            return(compressedPacket);
        }
        private static Smb2Packet CompressWithPatternV1(Smb2CompressiblePacket packet, Smb2CompressionInfo compressionInfo, Smb2Role role)
        {
            var data = packet.ToBytes();

            var dataToCompress = data;

            if (compressionInfo.CompressBufferOnly)
            {
                dataToCompress = data.Skip((packet as IPacketBuffer).BufferOffset).ToArray();
            }

            SMB2_COMPRESSION_PATTERN_PAYLOAD_V1?forwardDataPattern;

            SMB2_COMPRESSION_PATTERN_PAYLOAD_V1?backwardDataPattern;

            ScanForPatternV1(dataToCompress, out forwardDataPattern, out backwardDataPattern);

            if (forwardDataPattern == null && backwardDataPattern == null)
            {
                // Regress to non-chained since no pattern is found at front or end.
                return(CompressForNonChained(packet, compressionInfo, role));
            }

            var result = new Smb2ChainedCompressedPacket();

            result.OriginalPacket = packet;

            result.Header = new Compression_Transform_Header();

            result.Header.ProtocolId = Smb2Consts.ProtocolIdInCompressionTransformHeader;

            result.Header.OriginalCompressedSegmentSize = (UInt32)data.Length;

            result.Header.Flags = Compression_Transform_Header_Flags.SMB2_COMPRESSION_FLAG_CHAINED;

            var payloads = new List <Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object> >();

            bool isFirst = true;

            if (compressionInfo.CompressBufferOnly)
            {
                var header = data.Take((packet as IPacketBuffer).BufferOffset).ToArray();

                var payloadHeader = SMB2_COMPRESSION_PAYLOAD_HEADER.Create(CompressionAlgorithm.NONE, (UInt32)header.Length, 0, ref isFirst);

                payloads.Add(new Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object>(payloadHeader, header));
            }

            if (forwardDataPattern != null)
            {
                var payloadHeader = SMB2_COMPRESSION_PAYLOAD_HEADER.Create(CompressionAlgorithm.Pattern_V1, (UInt32)PatternPayloadLength, 0, ref isFirst);

                payloads.Add(new Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object>(payloadHeader, forwardDataPattern));
            }

            int forwardDataPatternLength = (int)(forwardDataPattern?.Repetitions ?? 0);

            int backwardDataPatternLength = (int)(backwardDataPattern?.Repetitions ?? 0);

            var innerData = dataToCompress.Skip(forwardDataPatternLength).Take(dataToCompress.Length - forwardDataPatternLength - backwardDataPatternLength).ToArray();

            if (innerData.Length > 0)
            {
                var innerPayload = ChainedCompressWithCompressionAlgorithm(innerData, compressionInfo, ref isFirst);

                payloads.Add(innerPayload);
            }

            if (backwardDataPattern != null)
            {
                var payloadHeader = SMB2_COMPRESSION_PAYLOAD_HEADER.Create(CompressionAlgorithm.Pattern_V1, (UInt32)PatternPayloadLength, 0, ref isFirst);

                payloads.Add(new Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object>(payloadHeader, backwardDataPattern));
            }

            result.Payloads = payloads.ToArray();

            return(result);
        }
        private static Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object> ChainedCompressWithCompressionAlgorithm(byte[] data, Smb2CompressionInfo compressionInfo, ref bool isFirst)
        {
            var compressionAlgorithm = GetPreferredCompressionAlgorithm(compressionInfo);

            SMB2_COMPRESSION_PAYLOAD_HEADER payloadHeader;

            bool isFirstCopy;

            isFirstCopy = isFirst;

            var compressedPayloadHeader = SMB2_COMPRESSION_PAYLOAD_HEADER.Create(compressionAlgorithm, 0, (UInt32)data.Length, ref isFirstCopy);

            isFirstCopy = isFirst;

            var uncompressedPayloadHeader = SMB2_COMPRESSION_PAYLOAD_HEADER.Create(CompressionAlgorithm.NONE, (UInt32)data.Length, 0, ref isFirstCopy);

            isFirst = isFirstCopy;

            byte[] payloadData;

            if (compressionAlgorithm != CompressionAlgorithm.NONE)
            {
                var compressor = GetCompressor(compressionAlgorithm);

                var compressedData = compressor.Compress(data);

                int compressedDataLength = TypeMarshal.ToBytes(compressedPayloadHeader).Length + compressedData.Length;

                int uncompressedDataLength = TypeMarshal.ToBytes(uncompressedPayloadHeader).Length + data.Length;

                if (compressedDataLength < uncompressedDataLength)
                {
                    compressedPayloadHeader.Length = (UInt32)(compressedData.Length + FieldSizeOriginalPayloadSize);

                    payloadHeader = compressedPayloadHeader;

                    payloadData = compressedData;
                }
                else
                {
                    payloadHeader = uncompressedPayloadHeader;

                    payloadData = data;
                }
            }
            else
            {
                payloadHeader = uncompressedPayloadHeader;

                payloadData = data;
            }

            return(new Tuple <SMB2_COMPRESSION_PAYLOAD_HEADER, object>(payloadHeader, payloadData));
        }