/// <summary>
/// Writes the current message to the specified <see cref="SshDataStream"/>.
/// </summary>
/// <param name="stream">The <see cref="SshDataStream"/> to write the message to.</param>
protected override void WriteBytes(SshDataStream stream)
{
const int sizeOfDataLengthBytes = 4;
var startPosition = stream.Position;
// skip 4 bytes for the length of the SFTP message data
stream.Seek(sizeOfDataLengthBytes, SeekOrigin.Current);
// write the SFTP message data to the stream
base.WriteBytes(stream);
// save where we were positioned when we finished writing the SSH message data
var endPosition = stream.Position;
// determine the length of the SSH message data
var dataLength = endPosition - startPosition - sizeOfDataLengthBytes;
// write the length of the SFTP message where we were positioned before we started
// writing the SFTP message data
stream.Position = startPosition;
stream.Write((uint) dataLength);
// move back to we were positioned when we finished writing the SFTP message data
stream.Position = endPosition;
}
internal byte[] GetPacket(byte paddingMultiplier, Compressor compressor)
{
const int outboundPacketSequenceSize = 4;
var messageLength = BufferCapacity;
SshDataStream sshDataStream;
if (messageLength == -1 || compressor != null)
{
sshDataStream = new SshDataStream(DefaultCapacity);
// skip:
// * 4 bytes for the outbound packet sequence
// * 4 bytes for the packet data length
// * one byte for the packet padding length
sshDataStream.Seek(outboundPacketSequenceSize + 4 + 1, SeekOrigin.Begin);
if (compressor != null)
{
// obtain uncompressed message payload
var uncompressedDataStream = new SshDataStream(messageLength != -1 ? messageLength : DefaultCapacity);
WriteBytes(uncompressedDataStream);
// compress message payload
var compressedMessageData = compressor.Compress(uncompressedDataStream.ToArray());
// add compressed message payload
sshDataStream.Write(compressedMessageData, 0, compressedMessageData.Length);
}
else
{
// add message payload
WriteBytes(sshDataStream);
}
messageLength = (int) sshDataStream.Length - (outboundPacketSequenceSize + 4 + 1);
var packetLength = messageLength + 4 + 1;
// determine the padding length
var paddingLength = GetPaddingLength(paddingMultiplier, packetLength);
// add padding bytes
var paddingBytes = new byte[paddingLength];
Randomizer.GetBytes(paddingBytes);
sshDataStream.Write(paddingBytes, 0, paddingLength);
var packetDataLength = GetPacketDataLength(messageLength, paddingLength);
// skip bytes for outbound packet sequence
sshDataStream.Seek(outboundPacketSequenceSize, SeekOrigin.Begin);
// add packet data length
sshDataStream.Write(packetDataLength.GetBytes(), 0, 4);
// add packet padding length
sshDataStream.WriteByte(paddingLength);
}
else
{
var packetLength = messageLength + 4 + 1;
// determine the padding length
var paddingLength = GetPaddingLength(paddingMultiplier, packetLength);
var packetDataLength = GetPacketDataLength(messageLength, paddingLength);
// lets construct an SSH data stream of the exact size required
sshDataStream = new SshDataStream(packetLength + paddingLength + outboundPacketSequenceSize);
// skip bytes for outbound packet sequenceSize
sshDataStream.Seek(outboundPacketSequenceSize, SeekOrigin.Begin);
// add packet data length
sshDataStream.Write(packetDataLength.GetBytes(), 0, 4);
// add packet padding length
sshDataStream.WriteByte(paddingLength);
// add message payload
WriteBytes(sshDataStream);
// add padding bytes
var paddingBytes = new byte[paddingLength];
Randomizer.GetBytes(paddingBytes);
sshDataStream.Write(paddingBytes, 0, paddingLength);
}
return sshDataStream.ToArray();
}
