/// <summary>
/// Reassemble several fragment PDUs to one PDU.<para/>
/// Must call after decrypt/verify.
/// </summary>
/// <param name="context">RpceContext to Reassemble PDU.</param>
/// <param name="pdus">Fragment PDUs to be reassembled.</param>
/// <returns>A ressembled PDU.</returns>
/// <exception cref="ArgumentNullException">
/// Thrown when pdus is null.
/// </exception>
/// <exception cref="ArgumentException">
/// Thrown when pdus is invalid.
/// </exception>
/// <exception cref="InvalidOperationException">Thrown when Speicified PDU doesn't
/// support fragment and reassemble.</exception>
public static RpceCoPdu ReassemblePdu(RpceContext context, params RpceCoPdu[] pdus)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
if (pdus == null)
{
throw new ArgumentNullException("pdus");
}
if (pdus.Length == 0)
{
throw new ArgumentException("There's no PDU to reassemble.", "pdus");
}
//verify if the fisrt pdu has the valid PFC_FIRST_FRAG.
if ((pdus[0].pfc_flags & RpceCoPfcFlags.PFC_FIRST_FRAG) == 0)
{
throw new ArgumentException("First PDU doesn't have PFC_FIRST_FRAG flag.", "pdus");
}
//verify if fragments end expected.
for (int i = 0; i < pdus.Length - 1; i++)
{
if ((pdus[i].pfc_flags & RpceCoPfcFlags.PFC_LAST_FRAG) != 0)
{
throw new ArgumentException("Fragments ended unexpected.", "pdus");
}
}
if ((pdus[pdus.Length - 1].pfc_flags & RpceCoPfcFlags.PFC_LAST_FRAG) == 0)
{
throw new ArgumentException("Fragments is not ended.", "pdus");
}
//All PTYPEs should be the same.
for (int i = 1; i < pdus.Length; i++)
{
if (pdus[i].PTYPE != pdus[0].PTYPE)
{
throw new ArgumentException("PDUs' PTYPE are different.", "pdus");
}
}
if (pdus.Length == 1)
{
return(pdus[0]);
}
RpceCoPdu reassembledPdu;
switch (pdus[0].PTYPE)
{
case RpcePacketType.Request:
RpceCoRequestPdu requestPdu = pdus[0] as RpceCoRequestPdu;
if (requestPdu == null)
{
throw new ArgumentException("The PDU is not a valid RpceCoRequestPdu");
}
for (int i = 1; i < pdus.Length; i++)
{
requestPdu.stub = ArrayUtility.ConcatenateArrays(
requestPdu.stub,
((RpceCoRequestPdu)pdus[i]).stub);
}
requestPdu.pfc_flags |= RpceCoPfcFlags.PFC_LAST_FRAG;
requestPdu.frag_length = (ushort)(requestPdu.GetSize() + requestPdu.stub.Length);
requestPdu.auth_length = 0;
requestPdu.auth_verifier = null;
reassembledPdu = requestPdu;
break;
case RpcePacketType.Response:
RpceCoResponsePdu responsePdu = pdus[0] as RpceCoResponsePdu;
if (responsePdu == null)
{
throw new ArgumentException("The PDU is not a valid RpceCoResponsePdu");
}
for (int i = 1; i < pdus.Length; i++)
{
responsePdu.stub = ArrayUtility.ConcatenateArrays(
responsePdu.stub,
((RpceCoResponsePdu)pdus[i]).stub);
}
responsePdu.pfc_flags |= RpceCoPfcFlags.PFC_LAST_FRAG;
responsePdu.frag_length = (ushort)(responsePdu.GetSize() + responsePdu.stub.Length);
responsePdu.auth_length = 0;
responsePdu.auth_verifier = null;
reassembledPdu = responsePdu;
break;
case RpcePacketType.Bind:
case RpcePacketType.BindAck:
case RpcePacketType.AlterContext:
case RpcePacketType.AlterContextResp:
case RpcePacketType.Auth3:
//Windows RPC support version 5.0 only.
//Bind fragment requires RPC ver 5.1.
//We don't support it.
throw new NotSupportedException("bind/bind_ack/alt_context/alt_context_resp/auth3 PDU fragment are not supported.");
default:
throw new InvalidOperationException("Speicified PDU doesn't support fragment and reassemble.");
}
return(reassembledPdu);
}
/// <summary>
/// Fragment a PDU into several PDUs by max_xmit_frag field.<para/>
/// Only bind, bind_ack, alter_context, alter_context_response,
/// request and response PDUs will be fragmented.<para/>
/// Must call before sign/encrypt.
/// </summary>
/// <param name="context">RpceContext to fragment PDU</param>
/// <param name="pdu">
/// A PDU to be fragmented.
/// Only bind, bind_ack, alter_context, alter_context_response,
/// request and response PDUs will be fragmented.
/// </param>
/// <returns>Fragmented PDUs.</returns>
/// <exception cref="ArgumentNullException">
/// Thrown when pdu or context is null.
/// </exception>
/// <exception cref="NotSupportedException">Thrown when PDU PacketType isn't supported.</exception>
public static RpceCoPdu[] FragmentPdu(RpceContext context, RpceCoPdu pdu)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
if (pdu == null)
{
throw new ArgumentNullException("pdu");
}
if (pdu.frag_length > context.MaxTransmitFragmentSize)
{
int headerAndTrailerSize;
byte[] stub;
switch (pdu.PTYPE)
{
case RpcePacketType.Request:
//Get stub of request PDU
RpceCoRequestPdu requestPdu = pdu as RpceCoRequestPdu;
if (requestPdu == null)
{
throw new ArgumentException("The pdu is not a valid RpceCoRequestPdu.");
}
headerAndTrailerSize = requestPdu.GetSize();
if (requestPdu.auth_verifier != null)
{
//length of auth_verifier
headerAndTrailerSize += RpceUtility.AUTH_VERIFIER_SIZE;
headerAndTrailerSize += requestPdu.auth_verifier.Value.auth_value.Length;
//To keep stub always be padded to 16 bytes, and pdu doesnot exceed max transmit frag size.
int stubLength = context.MaxTransmitFragmentSize - headerAndTrailerSize;
headerAndTrailerSize +=
RpceUtility.Align(stubLength, RpceUtility.AUTH_PAD_LENGTH) - stubLength;
//The beginning of the verification_trailer header MUST be 4-byte aligned
//with respect to the beginning of the PDU.
headerAndTrailerSize = RpceUtility.Align(headerAndTrailerSize, RpceUtility.STUB_PAD_LENGTH);
}
stub = requestPdu.stub ?? new byte[0];
//Fragment
RpceCoRequestPdu[] requestFragmentPduList = FragmentPdu <RpceCoRequestPdu>(
context,
pdu,
stub.Length,
headerAndTrailerSize);
for (int i = 0; i < requestFragmentPduList.Length; i++)
{
//SHOULD set the alloc_hint field in every PDU to
//be the combined stub data length of all remaining fragment PDUs.
requestFragmentPduList[i].alloc_hint = (uint)stub.Length;
requestFragmentPduList[i].p_cont_id = requestPdu.p_cont_id;
requestFragmentPduList[i].opnum = requestPdu.opnum;
requestFragmentPduList[i].@object = requestPdu.@object;
requestFragmentPduList[i].stub = ArrayUtility.SubArray(
stub,
0,
Math.Min(stub.Length, context.MaxTransmitFragmentSize - headerAndTrailerSize));
//For request and response PDUs, where the request and response PDUs are
//part of a fragmented request or response and authentication is requested,
//the sec_trailer structure MUST be present in every fragment of the request
//or response.
requestFragmentPduList[i].AppendAuthenticationVerifier();
requestFragmentPduList[i].SetLength();
stub = ArrayUtility.SubArray(stub, requestFragmentPduList[i].stub.Length);
}
return(requestFragmentPduList);
case RpcePacketType.Response:
//Get stub of response PDU
RpceCoResponsePdu responsePdu = pdu as RpceCoResponsePdu;
if (responsePdu == null)
{
throw new ArgumentException("The PDU is not a valid RpceCoResponsePdu");
}
headerAndTrailerSize = responsePdu.GetSize();
if (responsePdu.auth_verifier != null)
{
//length of auth_verifier
headerAndTrailerSize += RpceUtility.AUTH_VERIFIER_SIZE;
headerAndTrailerSize += responsePdu.auth_verifier.Value.auth_value.Length;
//To keep stub always be padded to 16 bytes, and pdu doesnot exceed max transmit frag size.
int stubLength = context.MaxTransmitFragmentSize - headerAndTrailerSize;
headerAndTrailerSize +=
RpceUtility.Align(stubLength, RpceUtility.AUTH_PAD_LENGTH) - stubLength;
//The beginning of the verification_trailer header MUST be 4-byte aligned
//with respect to the beginning of the PDU.
headerAndTrailerSize = RpceUtility.Align(headerAndTrailerSize, RpceUtility.STUB_PAD_LENGTH);
}
stub = responsePdu.stub ?? new byte[0];
//Fragment
RpceCoResponsePdu[] responseFragmentPduList = FragmentPdu <RpceCoResponsePdu>(
context,
pdu,
stub.Length,
headerAndTrailerSize);
for (int i = 0; i < responseFragmentPduList.Length; i++)
{
//SHOULD set the alloc_hint field in every PDU to
//be the combined stub data length of all remaining fragment PDUs.
responseFragmentPduList[i].alloc_hint = (uint)stub.Length;
responseFragmentPduList[i].p_cont_id = responsePdu.p_cont_id;
responseFragmentPduList[i].cancel_count = responsePdu.cancel_count;
responseFragmentPduList[i].reserved = responsePdu.reserved;
responseFragmentPduList[i].stub = ArrayUtility.SubArray(
stub,
0,
Math.Min(stub.Length, context.MaxTransmitFragmentSize - headerAndTrailerSize));
//For request and response PDUs, where the request and response PDUs are
//part of a fragmented request or response and authentication is requested,
//the sec_trailer structure MUST be present in every fragment of the request
//or response.
responseFragmentPduList[i].AppendAuthenticationVerifier();
responseFragmentPduList[i].SetLength();
stub = ArrayUtility.SubArray(stub, responseFragmentPduList[i].stub.Length);
}
return(responseFragmentPduList);
case RpcePacketType.Bind:
case RpcePacketType.BindAck:
case RpcePacketType.AlterContext:
case RpcePacketType.AlterContextResp:
case RpcePacketType.Auth3:
//Windows RPC support version 5.0 only.
//Bind fragment requires RPC ver 5.1.
//We don't support it.
throw new NotSupportedException("bind/bind_ack/alt_context/alt_context_resp/auth3 PDU fragment are not supported.");
default:
throw new InvalidOperationException("PDU PacketType isn't supported.");
}
}
//If we cannot fragment the PDU
return(new RpceCoPdu[] { pdu });
}
