/// <summary>
/// Writes the layer to the buffer.
/// </summary>
/// <param name="buffer">The buffer to write the layer to.</param>
/// <param name="offset">The offset in the buffer to start writing the layer at.</param>
/// <param name="payloadLength">The length of the layer's payload (the number of bytes after the layer in the packet).</param>
/// <param name="previousLayer">The layer that comes before this layer. null if this is the first layer.</param>
/// <param name="nextLayer">The layer that comes after this layer. null if this is the last layer.</param>
public override void Write(byte[] buffer, int offset, int payloadLength, ILayer previousLayer, ILayer nextLayer)
{
IpV4Protocol?nextLayerProtocol = null;
if (nextLayer != null)
{
IIpNextLayer ipNextLayer = nextLayer as IIpNextLayer;
if (ipNextLayer != null)
{
nextLayerProtocol = ipNextLayer.PreviousLayerProtocol;
}
}
if (nextLayer != null && ExtensionHeaders.LastHeader == IpV4Protocol.EncapsulatingSecurityPayload)
{
throw new ArgumentException("Cannot have a layer after IpV6Layer with EncapsulatingSecurityPayload extension header.", "nextLayer");
}
if (payloadLength + ExtensionHeaders.BytesLength > ushort.MaxValue)
{
throw new ArgumentOutOfRangeException("payloadLength", payloadLength,
"Consider the extension headers, this must be no more than " +
(ushort.MaxValue - ExtensionHeaders.BytesLength));
}
IpV6Datagram.WriteHeader(buffer, offset,
TrafficClass, FlowLabel, (ushort)(payloadLength + ExtensionHeaders.BytesLength), NextHeader, nextLayerProtocol, HopLimit, Source, CurrentDestination, ExtensionHeaders);
}
/// <summary>
/// Finalizes the layer data in the buffer.
/// Used for fields that must be calculated according to the layer's payload (like checksum).
/// </summary>
/// <param name="buffer">The buffer to finalize the layer in.</param>
/// <param name="offset">The offset in the buffer the layer starts.</param>
/// <param name="payloadLength">The length of the layer's payload (the number of bytes after the layer in the packet).</param>
/// <param name="nextLayer">The layer that comes after this layer. null if this is the last layer.</param>
public override void Finalize(byte[] buffer, int offset, int payloadLength, ILayer nextLayer)
{
IIpNextTransportLayer nextTransportLayer = nextLayer as IIpNextTransportLayer;
if (nextTransportLayer == null || !nextTransportLayer.CalculateChecksum)
{
return;
}
IpV6Datagram.WriteTransportChecksum(buffer, offset, Length, (uint)payloadLength,
nextTransportLayer.ChecksumOffset, nextTransportLayer.IsChecksumOptional,
nextTransportLayer.Checksum, CurrentDestination);
}