private void HandleRetransmittedHandshakeRecord(int epoch, byte[] buf, int off, int len)
{
/*
* TODO Need to handle the case where the previous inbound flight contains
* messages from two epochs.
*/
if (len < 12)
{
return;
}
int fragment_length = TlsUtilities.ReadUint24(buf, off + 9);
if (len != (fragment_length + 12))
{
return;
}
int seq = TlsUtilities.ReadUint16(buf, off + 4);
if (seq >= mNextReceiveSeq)
{
return;
}
byte msg_type = TlsUtilities.ReadUint8(buf, off);
// TODO This is a hack that only works until we try to support renegotiation
int expectedEpoch = msg_type == HandshakeType.finished ? 1 : 0;
if (epoch != expectedEpoch)
{
return;
}
int length = TlsUtilities.ReadUint24(buf, off + 1);
int fragment_offset = TlsUtilities.ReadUint24(buf, off + 6);
if (fragment_offset + fragment_length > length)
{
return;
}
DtlsReassembler reassembler = (DtlsReassembler)mCurrentInboundFlight[seq];
if (reassembler != null)
{
reassembler.ContributeFragment(msg_type, length, buf, off + 12, fragment_offset,
fragment_length);
if (CheckAll(mCurrentInboundFlight))
{
ResendOutboundFlight();
ResetAll(mCurrentInboundFlight);
}
}
}
internal Message ReceiveMessage()
{
if (mSending)
{
mSending = false;
PrepareInboundFlight();
}
// Check if we already have the next message waiting
{
DtlsReassembler next = (DtlsReassembler)mCurrentInboundFlight[mNextReceiveSeq];
if (next != null)
{
byte[] body = next.GetBodyIfComplete();
if (body != null)
{
mPreviousInboundFlight = null;
return(UpdateHandshakeMessagesDigest(new Message(mNextReceiveSeq++, next.MsgType, body)));
}
}
}
byte[] buf = null;
// TODO Check the conditions under which we should reset this
int readTimeoutMillis = 1000;
for (;;)
{
int receiveLimit = mRecordLayer.GetReceiveLimit();
if (buf == null || buf.Length < receiveLimit)
{
buf = new byte[receiveLimit];
}
// TODO Handle records containing multiple handshake messages
try
{
for (; ;)
{
int received = mRecordLayer.Receive(buf, 0, receiveLimit, readTimeoutMillis);
if (received < 0)
{
break;
}
if (received < 12)
{
continue;
}
int fragment_length = TlsUtilities.ReadUint24(buf, 9);
if (received != (fragment_length + 12))
{
continue;
}
int seq = TlsUtilities.ReadUint16(buf, 4);
if (seq > (mNextReceiveSeq + MAX_RECEIVE_AHEAD))
{
continue;
}
byte msg_type = TlsUtilities.ReadUint8(buf, 0);
int length = TlsUtilities.ReadUint24(buf, 1);
int fragment_offset = TlsUtilities.ReadUint24(buf, 6);
if (fragment_offset + fragment_length > length)
{
continue;
}
if (seq < mNextReceiveSeq)
{
/*
* NOTE: If we Receive the previous flight of incoming messages in full
* again, retransmit our last flight
*/
if (mPreviousInboundFlight != null)
{
DtlsReassembler reassembler = (DtlsReassembler)mPreviousInboundFlight[seq];
if (reassembler != null)
{
reassembler.ContributeFragment(msg_type, length, buf, 12, fragment_offset,
fragment_length);
if (CheckAll(mPreviousInboundFlight))
{
ResendOutboundFlight();
/*
* TODO[DTLS] implementations SHOULD back off handshake packet
* size during the retransmit backoff.
*/
readTimeoutMillis = System.Math.Min(readTimeoutMillis * 2, 60000);
ResetAll(mPreviousInboundFlight);
}
}
}
}
else
{
DtlsReassembler reassembler = (DtlsReassembler)mCurrentInboundFlight[seq];
if (reassembler == null)
{
reassembler = new DtlsReassembler(msg_type, length);
mCurrentInboundFlight[seq] = reassembler;
}
reassembler.ContributeFragment(msg_type, length, buf, 12, fragment_offset, fragment_length);
if (seq == mNextReceiveSeq)
{
byte[] body = reassembler.GetBodyIfComplete();
if (body != null)
{
mPreviousInboundFlight = null;
return(UpdateHandshakeMessagesDigest(new Message(mNextReceiveSeq++,
reassembler.MsgType, body)));
}
}
}
}
}
catch (IOException)
{
// NOTE: Assume this is a timeout for the moment
}
ResendOutboundFlight();
/*
* TODO[DTLS] implementations SHOULD back off handshake packet size during the
* retransmit backoff.
*/
readTimeoutMillis = System.Math.Min(readTimeoutMillis * 2, 60000);
}
}