//writer util
private SSH2DataWriter OpenWriter(AgentForwadPacketType pt)
{
SSH2DataWriter wr = new SSH2DataWriter();
wr.WriteInt32(0); //length field
wr.WriteByte((byte)pt);
return wr;
}
private byte[] DeriveKey(BigInteger key, byte[] hash, char ch, int length) {
byte[] result = new byte[length];
SSH2DataWriter wr = new SSH2DataWriter();
wr.WriteBigInteger(key);
wr.Write(hash);
wr.WriteByte((byte)ch);
wr.Write(_sessionID);
byte[] h1 = new SHA1CryptoServiceProvider().ComputeHash(wr.ToByteArray());
if (h1.Length >= length) {
Array.Copy(h1, 0, result, 0, length);
return result;
}
else {
wr = new SSH2DataWriter();
wr.WriteBigInteger(key);
wr.Write(_sessionID);
wr.Write(h1);
byte[] h2 = new SHA1CryptoServiceProvider().ComputeHash(wr.ToByteArray());
if (h1.Length + h2.Length >= length) {
Array.Copy(h1, 0, result, 0, h1.Length);
Array.Copy(h2, 0, result, h1.Length, length - h1.Length);
return result;
}
else
throw new SSHException("necessary key length is too big"); //long key is not supported
}
}
private bool ProcessPacket(DataFragment packet)
{
SSH2DataReader r = new SSH2DataReader(packet);
SSH2PacketType pt = (SSH2PacketType) r.ReadByte();
if (pt == SSH2PacketType.SSH_MSG_DISCONNECT) {
int errorcode = r.ReadInt32();
_eventReceiver.OnConnectionClosed();
return false;
}
else if (_waitingForPortForwardingResponse) {
if (pt != SSH2PacketType.SSH_MSG_REQUEST_SUCCESS)
_eventReceiver.OnUnknownMessage((byte)pt, packet.GetBytes());
_waitingForPortForwardingResponse = false;
return true;
}
else if (pt == SSH2PacketType.SSH_MSG_CHANNEL_OPEN) {
string method = r.ReadString();
if (method == "forwarded-tcpip")
ProcessPortforwardingRequest(_eventReceiver, r);
else if (method.StartsWith("auth-agent")) //in most cases, method is "*****@*****.**"
ProcessAgentForwardRequest(_eventReceiver, r);
else {
SSH2DataWriter wr = new SSH2DataWriter();
wr.WriteByte((byte)SSH2PacketType.SSH_MSG_CHANNEL_OPEN_FAILURE);
wr.WriteInt32(r.ReadInt32());
wr.WriteInt32(0);
wr.WriteString("unknown method");
wr.WriteString(""); //lang tag
TraceReceptionEvent("SSH_MSG_CHANNEL_OPEN rejected", "method={0}", method);
}
return true;
}
else if (pt >= SSH2PacketType.SSH_MSG_CHANNEL_OPEN_CONFIRMATION && pt <= SSH2PacketType.SSH_MSG_CHANNEL_FAILURE) {
int local_channel = r.ReadInt32();
ChannelCollection.Entry e = this.ChannelCollection.FindChannelEntry(local_channel);
if (e != null)
((SSH2Channel)e.Channel).ProcessPacket(e.Receiver, pt, r);
else
Debug.WriteLine("unexpected channel pt=" + pt + " local_channel=" + local_channel.ToString());
return true;
}
else if (pt == SSH2PacketType.SSH_MSG_IGNORE) {
_eventReceiver.OnIgnoreMessage(r.ReadByteString());
return true;
}
else if (_asyncKeyExchanger != null) {
_asyncKeyExchanger.AsyncProcessPacket(packet);
return true;
}
else if (pt == SSH2PacketType.SSH_MSG_KEXINIT) {
//Debug.WriteLine("Host sent KEXINIT");
_asyncKeyExchanger = new KeyExchanger(this, _sessionID);
_asyncKeyExchanger.AsyncProcessPacket(packet);
return true;
}
else {
_eventReceiver.OnUnknownMessage((byte)pt, packet.GetBytes());
return false;
}
}
