diff options
Diffstat (limited to 'core/src/main/java/org/spongycastle/crypto/tls/DTLSReliableHandshake.java')
| -rw-r--r-- | core/src/main/java/org/spongycastle/crypto/tls/DTLSReliableHandshake.java | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/tls/DTLSReliableHandshake.java b/core/src/main/java/org/spongycastle/crypto/tls/DTLSReliableHandshake.java new file mode 100644 index 00000000..d89dabca --- /dev/null +++ b/core/src/main/java/org/spongycastle/crypto/tls/DTLSReliableHandshake.java @@ -0,0 +1,453 @@ +package org.spongycastle.crypto.tls; + +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.util.Enumeration; +import java.util.Hashtable; +import java.util.Vector; + +import org.spongycastle.util.Integers; + +class DTLSReliableHandshake +{ + private final static int MAX_RECEIVE_AHEAD = 10; + + private final DTLSRecordLayer recordLayer; + + private TlsHandshakeHash handshakeHash; + + private Hashtable currentInboundFlight = new Hashtable(); + private Hashtable previousInboundFlight = null; + private Vector outboundFlight = new Vector(); + private boolean sending = true; + + private int message_seq = 0, next_receive_seq = 0; + + DTLSReliableHandshake(TlsContext context, DTLSRecordLayer transport) + { + this.recordLayer = transport; + this.handshakeHash = new DeferredHash(); + this.handshakeHash.init(context); + } + + void notifyHelloComplete() + { + this.handshakeHash = handshakeHash.notifyPRFDetermined(); + } + + TlsHandshakeHash getHandshakeHash() + { + return handshakeHash; + } + + TlsHandshakeHash prepareToFinish() + { + TlsHandshakeHash result = handshakeHash; + this.handshakeHash = handshakeHash.stopTracking(); + return result; + } + + void sendMessage(short msg_type, byte[] body) + throws IOException + { + TlsUtils.checkUint24(body.length); + + if (!sending) + { + checkInboundFlight(); + sending = true; + outboundFlight.removeAllElements(); + } + + Message message = new Message(message_seq++, msg_type, body); + + outboundFlight.addElement(message); + + writeMessage(message); + updateHandshakeMessagesDigest(message); + } + + byte[] receiveMessageBody(short msg_type) + throws IOException + { + Message message = receiveMessage(); + if (message.getType() != msg_type) + { + throw new TlsFatalAlert(AlertDescription.unexpected_message); + } + + return message.getBody(); + } + + Message receiveMessage() + throws IOException + { + if (sending) + { + sending = false; + prepareInboundFlight(); + } + + // Check if we already have the next message waiting + { + DTLSReassembler next = (DTLSReassembler)currentInboundFlight.get(Integers.valueOf(next_receive_seq)); + if (next != null) + { + byte[] body = next.getBodyIfComplete(); + if (body != null) + { + previousInboundFlight = null; + return updateHandshakeMessagesDigest(new Message(next_receive_seq++, next.getType(), body)); + } + } + } + + byte[] buf = null; + + // TODO Check the conditions under which we should reset this + int readTimeoutMillis = 1000; + + for (;;) + { + int receiveLimit = recordLayer.getReceiveLimit(); + if (buf == null || buf.length < receiveLimit) + { + buf = new byte[receiveLimit]; + } + + // TODO Handle records containing multiple handshake messages + + try + { + for (; ; ) + { + int received = recordLayer.receive(buf, 0, receiveLimit, readTimeoutMillis); + if (received < 0) + { + break; + } + if (received < 12) + { + continue; + } + int fragment_length = TlsUtils.readUint24(buf, 9); + if (received != (fragment_length + 12)) + { + continue; + } + int seq = TlsUtils.readUint16(buf, 4); + if (seq > (next_receive_seq + MAX_RECEIVE_AHEAD)) + { + continue; + } + short msg_type = TlsUtils.readUint8(buf, 0); + int length = TlsUtils.readUint24(buf, 1); + int fragment_offset = TlsUtils.readUint24(buf, 6); + if (fragment_offset + fragment_length > length) + { + continue; + } + + if (seq < next_receive_seq) + { + /* + * NOTE: If we receive the previous flight of incoming messages in full + * again, retransmit our last flight + */ + if (previousInboundFlight != null) + { + DTLSReassembler reassembler = (DTLSReassembler)previousInboundFlight.get(Integers + .valueOf(seq)); + if (reassembler != null) + { + reassembler.contributeFragment(msg_type, length, buf, 12, fragment_offset, + fragment_length); + + if (checkAll(previousInboundFlight)) + { + resendOutboundFlight(); + + /* + * TODO[DTLS] implementations SHOULD back off handshake packet + * size during the retransmit backoff. + */ + readTimeoutMillis = Math.min(readTimeoutMillis * 2, 60000); + + resetAll(previousInboundFlight); + } + } + } + } + else + { + DTLSReassembler reassembler = (DTLSReassembler)currentInboundFlight.get(Integers.valueOf(seq)); + if (reassembler == null) + { + reassembler = new DTLSReassembler(msg_type, length); + currentInboundFlight.put(Integers.valueOf(seq), reassembler); + } + + reassembler.contributeFragment(msg_type, length, buf, 12, fragment_offset, fragment_length); + + if (seq == next_receive_seq) + { + byte[] body = reassembler.getBodyIfComplete(); + if (body != null) + { + previousInboundFlight = null; + return updateHandshakeMessagesDigest(new Message(next_receive_seq++, + reassembler.getType(), body)); + } + } + } + } + } + catch (IOException e) + { + // NOTE: Assume this is a timeout for the moment + } + + resendOutboundFlight(); + + /* + * TODO[DTLS] implementations SHOULD back off handshake packet size during the + * retransmit backoff. + */ + readTimeoutMillis = Math.min(readTimeoutMillis * 2, 60000); + } + } + + void finish() + { + DTLSHandshakeRetransmit retransmit = null; + if (!sending) + { + checkInboundFlight(); + } + else if (currentInboundFlight != null) + { + /* + * RFC 6347 4.2.4. In addition, for at least twice the default MSL defined for [TCP], + * when in the FINISHED state, the node that transmits the last flight (the server in an + * ordinary handshake or the client in a resumed handshake) MUST respond to a retransmit + * of the peer's last flight with a retransmit of the last flight. + */ + retransmit = new DTLSHandshakeRetransmit() + { + public void receivedHandshakeRecord(int epoch, byte[] buf, int off, int len) + throws IOException + { + /* + * TODO Need to handle the case where the previous inbound flight contains + * messages from two epochs. + */ + if (len < 12) + { + return; + } + int fragment_length = TlsUtils.readUint24(buf, off + 9); + if (len != (fragment_length + 12)) + { + return; + } + int seq = TlsUtils.readUint16(buf, off + 4); + if (seq >= next_receive_seq) + { + return; + } + + short msg_type = TlsUtils.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 = TlsUtils.readUint24(buf, off + 1); + int fragment_offset = TlsUtils.readUint24(buf, off + 6); + if (fragment_offset + fragment_length > length) + { + return; + } + + DTLSReassembler reassembler = (DTLSReassembler)currentInboundFlight.get(Integers.valueOf(seq)); + if (reassembler != null) + { + reassembler.contributeFragment(msg_type, length, buf, off + 12, fragment_offset, + fragment_length); + if (checkAll(currentInboundFlight)) + { + resendOutboundFlight(); + resetAll(currentInboundFlight); + } + } + } + }; + } + + recordLayer.handshakeSuccessful(retransmit); + } + + void resetHandshakeMessagesDigest() + { + handshakeHash.reset(); + } + + /** + * Check that there are no "extra" messages left in the current inbound flight + */ + private void checkInboundFlight() + { + Enumeration e = currentInboundFlight.keys(); + while (e.hasMoreElements()) + { + Integer key = (Integer)e.nextElement(); + if (key.intValue() >= next_receive_seq) + { + // TODO Should this be considered an error? + } + } + } + + private void prepareInboundFlight() + { + resetAll(currentInboundFlight); + previousInboundFlight = currentInboundFlight; + currentInboundFlight = new Hashtable(); + } + + private void resendOutboundFlight() + throws IOException + { + recordLayer.resetWriteEpoch(); + for (int i = 0; i < outboundFlight.size(); ++i) + { + writeMessage((Message)outboundFlight.elementAt(i)); + } + } + + private Message updateHandshakeMessagesDigest(Message message) + throws IOException + { + if (message.getType() != HandshakeType.hello_request) + { + byte[] body = message.getBody(); + byte[] buf = new byte[12]; + TlsUtils.writeUint8(message.getType(), buf, 0); + TlsUtils.writeUint24(body.length, buf, 1); + TlsUtils.writeUint16(message.getSeq(), buf, 4); + TlsUtils.writeUint24(0, buf, 6); + TlsUtils.writeUint24(body.length, buf, 9); + handshakeHash.update(buf, 0, buf.length); + handshakeHash.update(body, 0, body.length); + } + return message; + } + + private void writeMessage(Message message) + throws IOException + { + int sendLimit = recordLayer.getSendLimit(); + int fragmentLimit = sendLimit - 12; + + // TODO Support a higher minimum fragment size? + if (fragmentLimit < 1) + { + // TODO Should we be throwing an exception here? + throw new TlsFatalAlert(AlertDescription.internal_error); + } + + int length = message.getBody().length; + + // NOTE: Must still send a fragment if body is empty + int fragment_offset = 0; + do + { + int fragment_length = Math.min(length - fragment_offset, fragmentLimit); + writeHandshakeFragment(message, fragment_offset, fragment_length); + fragment_offset += fragment_length; + } + while (fragment_offset < length); + } + + private void writeHandshakeFragment(Message message, int fragment_offset, int fragment_length) + throws IOException + { + RecordLayerBuffer fragment = new RecordLayerBuffer(12 + fragment_length); + TlsUtils.writeUint8(message.getType(), fragment); + TlsUtils.writeUint24(message.getBody().length, fragment); + TlsUtils.writeUint16(message.getSeq(), fragment); + TlsUtils.writeUint24(fragment_offset, fragment); + TlsUtils.writeUint24(fragment_length, fragment); + fragment.write(message.getBody(), fragment_offset, fragment_length); + + fragment.sendToRecordLayer(recordLayer); + } + + private static boolean checkAll(Hashtable inboundFlight) + { + Enumeration e = inboundFlight.elements(); + while (e.hasMoreElements()) + { + if (((DTLSReassembler)e.nextElement()).getBodyIfComplete() == null) + { + return false; + } + } + return true; + } + + private static void resetAll(Hashtable inboundFlight) + { + Enumeration e = inboundFlight.elements(); + while (e.hasMoreElements()) + { + ((DTLSReassembler)e.nextElement()).reset(); + } + } + + static class Message + { + private final int message_seq; + private final short msg_type; + private final byte[] body; + + private Message(int message_seq, short msg_type, byte[] body) + { + this.message_seq = message_seq; + this.msg_type = msg_type; + this.body = body; + } + + public int getSeq() + { + return message_seq; + } + + public short getType() + { + return msg_type; + } + + public byte[] getBody() + { + return body; + } + } + + static class RecordLayerBuffer extends ByteArrayOutputStream + { + RecordLayerBuffer(int size) + { + super(size); + } + + void sendToRecordLayer(DTLSRecordLayer recordLayer) throws IOException + { + recordLayer.send(buf, 0, count); + buf = null; + } + } +} |