Using ZIP content for delivery over HTTP

using System;
using System.IO;
using System.Text;

namespace HttpZipFolder
{
    static class ZipUtils
    {
        internal const uint LocalFileHeaderSignature = 0x04034b50;
        internal const uint DataDescriptorSignature = 0x08074b50;
        internal const uint FileHeaderSignature = 0x02014b50;
        internal const uint EndOfCentralDirectoryRecordSignature = 0x06054b50;

        internal const ushort NoCompressionMethod = 0;
        internal const ushort DeflateCompressionMethod = 8;

        internal static uint Read32(Stream s)
        {
            return BitConverter.ToUInt32(ReadBytes(s, 4), 0);
        }

        internal static ushort Read16(Stream s)
        {
            return BitConverter.ToUInt16(ReadBytes(s, 2), 0);
        }

        internal static byte[] ReadBytes(Stream s, int length)
        {
            byte[] buffer = new byte[length];
            int read = s.Read(buffer, 0, length);

            if (read != length) return null;
            return buffer;
        }

        internal static void Set16(byte[] buffer, int offset, ushort value)
        {
            byte[] data = BitConverter.GetBytes(value);
            Array.Copy(data, 0, buffer, offset, data.Length);
        }

        internal static void Set32(byte[] buffer, int offset, uint value)
        {
            byte[] data = BitConverter.GetBytes(value);
            Array.Copy(data, 0, buffer, offset, data.Length);
        }

        internal static ushort Get16(byte[] buffer, int offset)
        {
            return BitConverter.ToUInt16(buffer, offset);
        }

        internal static uint Get32(byte[] buffer, int offset)
        {
            return BitConverter.ToUInt32(buffer, offset);
        }

        internal static void Write32(Stream s, uint value)
        {
            byte[] data = BitConverter.GetBytes(value);
            s.Write(data, 0, data.Length);
        }

        internal static string ConvertToString(byte[] data)
        {
            return Encoding.Default.GetString(data);
        }

        internal static byte[] ConvertFromString(string s)
        {
            return Encoding.Default.GetBytes(s);
        }

        internal static DateTime ConvertToDataTime(uint packedDateTime)
        {
            int year = 1980 + (int)((packedDateTime >> 25) & 0x7F);
            int month = (int)(packedDateTime >> 21) & 0x0F;
            int day = (int)(packedDateTime >> 16) & 0x1F;
            int hours = (int)(packedDateTime >> 11) & 0x1F;
            int minutes = (int)(packedDateTime >> 5) & 0x3F;
            int seconds = (int)(packedDateTime & 0x1F) << 1;
            return new DateTime(year, month, day, hours, minutes, seconds);
        }

        internal static uint ConvertFromDataTime(DateTime dateTime)
        {
            int withoutYear = dateTime.Month << 21 | dateTime.Day << 16 |
                dateTime.Hour << 11 | dateTime.Minute << 5 | (dateTime.Second >> 1);
            return (uint)withoutYear | (uint)((dateTime.Year - 1980) << 25);
        }

        internal class LocalFileHeaderOffset
        {
            internal const int Version = 0;
            internal const int Flag = 2;
            internal const int CompressionMethod = 4;
            internal const int Modified = 6;
            internal const int Crc32 = 10;
            internal const int CompressedSize = 14;
            internal const int Size = 18;
            internal const int FilenameLength = 22;
            internal const int ExtrasLength = 24;

            internal const int TotalStructureSize = 26;
        }

        internal class FileHeaderOffset
        {
            internal const int VersionMade = 0;
            internal const int Version = 2;
            internal const int Flag = 4;
            internal const int CompressionMethod = 6;
            internal const int Modified = 8;
            internal const int Crc32 = 12;
            internal const int CompressedSize = 16;
            internal const int Size = 20;
            internal const int FilenameLength = 24;
            internal const int ExtrasLength = 26;
            internal const int CommentsLength = 28;

            internal const int TotalStructureSize = 42;
        }

        internal class EndOfCentralDirectoryOffset
        {
            internal const int Disk = 0;
            internal const int StartDisk = 2;
            internal const int DiskEntries = 4;
            internal const int TotalEntries = 6;
            internal const int DirectorySize = 8;
            internal const int DirectoryOffset = 12;
            internal const int CommentsLength = 16;

            internal const int TotalStructureSize = 18;
        }
    }
}