/// <summary>
/// Decode the KRB_ERROR token got from application.
/// </summary>
/// <param name="errorToken">The token got from an application message. This argument cannot be null.</param>
/// <returns>The decoded AP response.</returns>
/// <exception cref="System.ArgumentNullException">Thrown when the input parameter is null.</exception>
/// <exception cref="System.FormatException">Thrown when the errorToken is not valid.</exception>
public KileKrbError ParseKrbError(byte[] errorToken)
{
if (errorToken == null)
{
throw new ArgumentNullException("errorToken");
}
byte[] errorBody = KileUtility.VerifyGssApiTokenHeader(errorToken);
// Check if it has a two-byte tok_id
if (errorBody == null || errorBody.Length <= sizeof(TOK_ID))
{
throw new FormatException("Not a valid KRB_ERROR token!");
}
TOK_ID id = (TOK_ID)KileUtility.ConvertEndian(BitConverter.ToUInt16(errorBody, 0));
if (id != TOK_ID.KRB_ERROR)
{
throw new FormatException("Not a valid KRB_ERROR token!");
}
errorBody = ArrayUtility.SubArray(errorBody, sizeof(TOK_ID));
KileKrbError error = new KileKrbError();
error.FromBytes(errorBody);
return(error);
}
/// <summary>
/// Decode KILE PDUs from received message bytes
/// </summary>
/// <param name="endPoint">An endpoint from which the message bytes are received</param>
/// <param name="receivedBytes">The received bytes to be decoded</param>
/// <param name="consumedLength">Length of message bytes consumed by decoder</param>
/// <param name="expectedLength">Length of message bytes the decoder expects to receive</param>
/// <returns>The decoded KILE PDUs</returns>
/// <exception cref="System.FormatException">thrown when a kile message type is unsupported</exception>
internal KilePdu[] DecodePacketCallback(object endPoint,
byte[] receivedBytes,
out int consumedLength,
out int expectedLength)
{
// initialize lengths
consumedLength = 0;
expectedLength = 0;
if (null == receivedBytes || 0 == receivedBytes.Length)
{
return(null);
}
if (!isClientRole)
{
serverContext = null;
if (serverContextList != null)
{
KileConnection kileConnection = new KileConnection((IPEndPoint)endPoint);
if (!serverContextList.ContainsKey(kileConnection))
{
serverContext = new KileServerContext();
serverContext.TransportType = connectionType;
serverContextList.Add(kileConnection, serverContext);
}
else
{
serverContext = serverContextList[kileConnection];
}
}
if (serverContext == null)
{
throw new InvalidOperationException("The kileConnection related context does not exist.");
}
}
// TCP has a 4 bytes length header, while UDP has not
byte[] pduBytes = receivedBytes;
if ((isClientRole && clientContext.TransportType == KileConnectionType.TCP) ||
(!isClientRole && serverContext.TransportType == KileConnectionType.TCP))
{
// insufficient data, needs to receive more
if (receivedBytes.Length < sizeof(int))
{
return(null);
}
// get pdu data length
byte[] lengthBytes = ArrayUtility.SubArray(receivedBytes, 0, sizeof(int));
Array.Reverse(lengthBytes);
int pduLength = BitConverter.ToInt32(lengthBytes, 0);
// insufficient data, needs to receive more
expectedLength = sizeof(int) + pduLength;
if (receivedBytes.Length < expectedLength)
{
return(null);
}
// check if it is a krb zero message
if (pduLength == 0 && receivedBytes.Length == sizeof(int))
{
consumedLength = sizeof(int);
KrbZero krbZeroPdu = new KrbZero(clientContext);
return(new KilePdu[] { krbZeroPdu });
}
// remove length header from pdu bytes
pduBytes = ArrayUtility.SubArray <byte>(receivedBytes, sizeof(int), pduLength);
}
else
{
// UDP has no length header
expectedLength = pduBytes.Length;
}
// get message type
// (the lower 5 bits indicates its kile message type)
MsgType kileMessageType = (MsgType)(pduBytes[0] & 0x1f);
// decode according to message type
consumedLength = expectedLength;
KilePdu pdu = null;
switch (kileMessageType)
{
case MsgType.KRB_AS_REQ:
pdu = new KileAsRequest(serverContext);
break;
case MsgType.KRB_AS_RESP:
pdu = new KileAsResponse(clientContext);
break;
case MsgType.KRB_TGS_REQ:
pdu = new KileTgsRequest(serverContext);
break;
case MsgType.KRB_TGS_RESP:
pdu = new KileTgsResponse(clientContext);
break;
case MsgType.KRB_ERROR:
pdu = new KileKrbError();
break;
default:
throw new FormatException(
"Unsupported Message Type: " + kileMessageType.ToString());
}
pdu.FromBytes(pduBytes);
// update context
if (isClientRole)
{
clientContext.UpdateContext(pdu);
}
else
{
serverContext.UpdateContext(pdu);
}
return(new KilePdu[] { pdu });
}