Google.SafeBrowsing.API.ParseChunkData C# (CSharp) Method

        private IEnumerable<Chunk> ParseChunkData(Stream stream, string listName)
        {
            var redirects = new List<string>();
            byte[] buffer = new byte[1048576]; //1MB

            //safe method to read the data
            using (MemoryStream ms = new MemoryStream())
            {
                while (true)
                {
                    int read = stream.Read(buffer, 0, buffer.Length);
                    if (read <= 0)
                    {
                        buffer = ms.ToArray();
                        break;
                    }
                    ms.Write(buffer, 0, read);
                }
            }

            var dict = new List<Chunk>();

            int mode = 0xA;
            int position = 0;
            bool error = false;
            int chunkLen = 0;
            int count = 0;
            int startPos = 0;
            bool isBlackList = false;
            int chunkId = 0;

            while (position < buffer.Length)
            {
                switch (buffer[position])
                {
                    case 0x61: //'a'
                        if (mode != 0xA)
                        {
                            error = true;
                            break;
                        }

                        isBlackList = false;
                        mode = 0xB;
                        ++position;
                        break;
                    case 0x73: //'s'
                        if (mode != 0xA)
                        {
                            error = true;
                            break;
                        }

                        isBlackList = true;
                        mode = 0xB;
                        ++position;
                        break;
                    case 0x3A: //':'
                        if (mode == 0xB)
                        {
                            chunkId = ReadNumber(buffer, ++position, out position);
                            mode = 0xC;
                        }
                        else if (mode == 0xC)
                        {
                            ReadNumber(buffer, ++position, out position);
                            //hashlength igonored, assumed 4
                            mode = 0xD;
                        }
                        else if (mode == 0xD)
                        {
                            chunkLen = ReadNumber(buffer, ++position, out position);
                            mode = 0xE;
                        }
                        else
                        {
                            error = true;
                        }
                        break;
                    case 0xA: //'\n'
                        if (mode != 0xE)
                        {
                            error = true;
                            break;
                        }

                        startPos = ++position;

                        while ((position - startPos) < chunkLen)
                        {
                            dict.Add(new Chunk()
                            {
                                ChunkId = chunkId,
                                IsBlackList = isBlackList,
                                Key = DecodeNumber(buffer, position, out position),
                                List = listName,
                                IsHost = true
                            });

                            count = (int)buffer[position++];

                            if (!isBlackList)
                            {
                                for (int i = 0; i < count; i++)
                                    dict.Add(new Chunk()
                                    {
                                        ChunkId = chunkId,
                                        IsBlackList = isBlackList,
                                        Key = DecodeNumber(buffer, position, out position),
                                        List = listName,
                                        IsHost = false
                                    });
                            }
                            else    //'s'
                            {
                                for (int i = 0; i < count; i++)
                                {
                                    position += 4;  //skip chunknum
                                    dict.Add(new Chunk()
                                    {
                                        ChunkId = chunkId,
                                        IsBlackList = isBlackList,
                                        Key = DecodeNumber(buffer, position, out position),
                                        List = listName,
                                        IsHost = false
                                    });
                                }
                                if (count < 1)
                                    position += 4;  //skip chunknum
                            }
                        }

                        mode = 0xA;
                        break;
                    case 0:
                        if (mode != 0xA)
                            error = true;
                        position = buffer.Length;   //exit the FSM
                        break;
                    default:
                        error = true;
                        break;
                }

                if (error)
                    break;
            }

            return dict;
        }