internal static void WriteHeader(byte[] buffer, int offset,
byte typeOfService, ushort identification,
IpV4Fragmentation fragmentation,
byte ttl, IpV4Protocol protocol, ushort?headerChecksum,
IpV4Address source, IpV4Address destination,
IpV4Options options, int payloadLength)
{
int headerLength = HeaderMinimumLength + options.BytesLength;
buffer[offset + Offset.VersionAndHeaderLength] = (byte)((DefaultVersion << 4) + headerLength / 4);
buffer[offset + Offset.TypeOfService] = typeOfService;
buffer.Write(offset + Offset.TotalLength, (ushort)(headerLength + payloadLength), Endianity.Big);
buffer.Write(offset + Offset.Identification, identification, Endianity.Big);
fragmentation.Write(buffer, offset + Offset.Fragmentation);
buffer[offset + Offset.Ttl] = ttl;
buffer[offset + Offset.Protocol] = (byte)protocol;
buffer.Write(offset + Offset.Source, source, Endianity.Big);
buffer.Write(offset + Offset.Destination, destination, Endianity.Big);
options.Write(buffer, offset + Offset.Options);
ushort headerChecksumValue =
headerChecksum == null
? Sum16BitsToChecksum(Sum16Bits(buffer, offset, headerLength))
: headerChecksum.Value;
buffer.Write(offset + Offset.HeaderChecksum, headerChecksumValue, Endianity.Big);
}
internal static void WriteHeader(byte[] buffer, int offset, byte typeOfService, ushort identification, IpV4Fragmentation fragmentation, byte ttl, IpV4Protocol protocol, ushort?headerChecksum, IpV4Address source, IpV4Address destination, IpV4Options options, int payloadLength)
{
int length = 20 + options.BytesLength;
buffer[offset] = (byte)(64 + length / 4);
buffer[offset + 1] = typeOfService;
ByteArrayExtensions.Write(buffer, offset + 2, (ushort)(length + payloadLength), Endianity.Big);
ByteArrayExtensions.Write(buffer, offset + 4, identification, Endianity.Big);
fragmentation.Write(buffer, offset + 6);
buffer[offset + 8] = ttl;
buffer[offset + 9] = (byte)protocol;
ByteArrayExtensions.Write(buffer, offset + 12, source, Endianity.Big);
ByteArrayExtensions.Write(buffer, offset + 16, destination, Endianity.Big);
options.Write(buffer, offset + 20);
ushort?nullable = headerChecksum;
ushort num = !(nullable.HasValue ? new int?((int)nullable.GetValueOrDefault()) : new int?()).HasValue ? DataSegment.Sum16BitsToChecksum(DataSegment.Sum16Bits(buffer, offset, length)) : headerChecksum.Value;
ByteArrayExtensions.Write(buffer, offset + 10, num, Endianity.Big);
}
