/**
* We found a non-SYN packet that was queued in the syn queue, check to see if it has a home now,
* else drop it ...
*/
private void reReceivePacket(Packet packet) {
Connection con = _manager.getConnectionByOutboundId(packet.getReceiveStreamId());
if (con != null) {
// Send it through the packet handler again
if (_log.shouldLog(Log.WARN)) _log.warn("Found con for queued non-syn packet: " + packet);
// false -> don't requeue, fixes a race where a SYN gets dropped
// between here and PacketHandler, causing the packet to loop forever....
_manager.getPacketHandler().receivePacketDirect(packet, false);
} else {
// goodbye
if (_log.shouldLog(Log.WARN))
_log.warn("Did not find con for queued non-syn packet, dropping: " + packet);
packet.releasePayload();
}
}
/**
* This sends a reset back to the place this packet came from. If the packet has no 'optional
* from' or valid signature, this does nothing. This is not associated with a connection, so no
* con stats are updated.
*/
private void sendReset(Packet packet) {
Destination from = packet.getOptionalFrom();
if (from == null) return;
boolean ok = packet.verifySignature(_context, from, null);
if (!ok) {
if (_log.shouldLog(Log.WARN))
_log.warn("Can't send reset after recv spoofed packet: " + packet);
return;
}
PacketLocal reply = new PacketLocal(_context, from);
reply.setFlag(Packet.FLAG_RESET);
reply.setFlag(Packet.FLAG_SIGNATURE_INCLUDED);
reply.setSendStreamId(packet.getReceiveStreamId());
reply.setReceiveStreamId(packet.getSendStreamId());
reply.setOptionalFrom(_manager.getSession().getMyDestination());
// this just sends the packet - no retries or whatnot
_manager.getPacketQueue().enqueue(reply);
}
private void sendReset(Packet packet) {
boolean ok = packet.verifySignature(_context, packet.getOptionalFrom(), null);
if (!ok) {
if (_log.shouldLog(Log.WARN))
_log.warn("Received a spoofed SYN packet: they said they were " + packet.getOptionalFrom());
return;
}
PacketLocal reply = new PacketLocal(_context, packet.getOptionalFrom());
reply.setFlag(Packet.FLAG_RESET);
reply.setFlag(Packet.FLAG_SIGNATURE_INCLUDED);
reply.setAckThrough(packet.getSequenceNum());
reply.setSendStreamId(packet.getReceiveStreamId());
reply.setReceiveStreamId(0);
reply.setOptionalFrom(_manager.getSession().getMyDestination());
if (_log.shouldLog(Log.DEBUG)) _log.debug("Sending RST: " + reply + " because of " + packet);
// this just sends the packet - no retries or whatnot
_manager.getPacketQueue().enqueue(reply);
}
/**
* We found a non-SYN packet that was queued in the syn queue, check to see if it has a home now,
* else drop it ...
*/
private void reReceivePacket(Packet packet) {
Connection con = _manager.getConnectionByOutboundId(packet.getReceiveStreamId());
if (con != null) {
// Send it through the packet handler again
if (_log.shouldLog(Log.WARN)) _log.warn("Found con for queued non-syn packet: " + packet);
// false -> don't requeue, fixes a race where a SYN gets dropped
// between here and PacketHandler, causing the packet to loop forever....
_manager.getPacketHandler().receivePacketDirect(packet, false);
} else {
// log it here, just before we kill it - dest will be unknown
if (I2PSocketManagerFull.pcapWriter != null
&& _context.getBooleanProperty(I2PSocketManagerFull.PROP_PCAP)) packet.logTCPDump(null);
// goodbye
if (_log.shouldLog(Log.WARN))
_log.warn("Did not find con for queued non-syn packet, dropping: " + packet);
packet.releasePayload();
}
}
private void receivePong(Packet packet) {
_manager.receivePong(packet.getReceiveStreamId());
}
private void receiveUnknownCon(Packet packet, long sendId, boolean queueIfNoConn) {
if (packet.isFlagSet(Packet.FLAG_ECHO)) {
if (packet.getSendStreamId() > 0) {
if (_manager.answerPings()) receivePing(packet);
else if (_log.shouldLog(Log.WARN))
_log.warn("Dropping Echo packet on unknown con: " + packet);
} else if (packet.getReceiveStreamId() > 0) {
receivePong(packet);
} else {
if (_log.shouldLog(Log.WARN))
_log.warn("Echo packet received with no stream IDs: " + packet);
}
packet.releasePayload();
} else {
if (_log.shouldLog(Log.WARN) && !packet.isFlagSet(Packet.FLAG_SYNCHRONIZE))
_log.warn("Packet received on an unknown stream (and not an ECHO or SYN): " + packet);
if (sendId <= 0) {
Connection con = _manager.getConnectionByOutboundId(packet.getReceiveStreamId());
if (con != null) {
if ((con.getHighestAckedThrough() <= 5) && (packet.getSequenceNum() <= 5)) {
if (_log.shouldLog(Log.WARN))
_log.warn(
"Received additional packet w/o SendStreamID after the syn on "
+ con
+ ": "
+ packet);
receiveKnownCon(con, packet);
return;
} else {
if (_log.shouldLog(Log.WARN))
_log.warn(
"hrmph, received while ack of syn was in flight on "
+ con
+ ": "
+ packet
+ " acked: "
+ con.getAckedPackets());
// allow unlimited packets without a SendStreamID for now
receiveKnownCon(con, packet);
return;
}
}
}
if (packet.isFlagSet(Packet.FLAG_SYNCHRONIZE)) {
// logTCPDump() will be called in ConnectionManager.receiveConnection(),
// which is called by ConnectionHandler.receiveNewSyn(),
// after we have a new conn, which makes the logging better.
_manager.getConnectionHandler().receiveNewSyn(packet);
} else if (queueIfNoConn) {
// don't call logTCPDump() here, wait for it to find a conn
// We can get here on the 2nd+ packet if the 1st (SYN) packet
// is still on the _synQueue in the ConnectionHandler, and
// ConnectionManager.receiveConnection() hasn't run yet to put
// the StreamID on the getConnectionByOutboundId list.
// Then the 2nd packet gets discarded and has to be retransmitted.
//
// We fix this by putting this packet on the syn queue too!
// Then ConnectionHandler.accept() will check the connection list
// and call receivePacket() above instead of receiveConnection().
if (_log.shouldLog(Log.WARN)) {
_log.warn("Packet belongs to no other cons, putting on the syn queue: " + packet);
}
if (_log.shouldLog(Log.DEBUG)) {
StringBuilder buf = new StringBuilder(128);
for (Connection con : _manager.listConnections()) {
buf.append(con.toString()).append(" ");
}
_log.debug(
"connections: "
+ buf.toString()
+ " sendId: "
+ (sendId > 0 ? Packet.toId(sendId) : " unknown"));
}
// packet.releasePayload();
_manager.getConnectionHandler().receiveNewSyn(packet);
} else {
// log it here, just before we kill it - dest will be unknown
if (I2PSocketManagerFull.pcapWriter != null
&& _context.getBooleanProperty(I2PSocketManagerFull.PROP_PCAP)) packet.logTCPDump(null);
// don't queue again (infinite loop!)
sendReset(packet);
packet.releasePayload();
}
}
}
private void receiveKnownCon(Connection con, Packet packet) {
// is this ok here or does it need to be below each packetHandler().receivePacket() ?
if (I2PSocketManagerFull.pcapWriter != null
&& _context.getBooleanProperty(I2PSocketManagerFull.PROP_PCAP)) packet.logTCPDump(con);
if (packet.isFlagSet(Packet.FLAG_ECHO)) {
if (packet.getSendStreamId() > 0) {
if (con.getOptions().getAnswerPings()) receivePing(packet);
else if (_log.shouldLog(Log.WARN))
_log.warn("Dropping Echo packet on existing con: " + packet);
} else if (packet.getReceiveStreamId() > 0) {
receivePong(packet);
} else {
if (_log.shouldLog(Log.WARN))
_log.warn("Echo packet received with no stream IDs: " + packet);
}
packet.releasePayload();
return;
}
// the packet is pointed at a stream ID we're receiving on
if (isValidMatch(con.getSendStreamId(), packet.getReceiveStreamId())) {
// the packet's receive stream ID also matches what we expect
// if (_log.shouldLog(Log.DEBUG))
// _log.debug("receive valid: " + packet);
try {
con.getPacketHandler().receivePacket(packet, con);
} catch (I2PException ie) {
if (_log.shouldLog(Log.WARN)) _log.warn("Received forged packet for " + con, ie);
}
} else {
if (packet.isFlagSet(Packet.FLAG_RESET)) {
// refused
if (_log.shouldLog(Log.DEBUG)) _log.debug("receive reset: " + packet);
try {
con.getPacketHandler().receivePacket(packet, con);
} catch (I2PException ie) {
if (_log.shouldLog(Log.WARN)) _log.warn("Received forged reset for " + con, ie);
}
} else {
if ((con.getSendStreamId() <= 0)
|| (con.getSendStreamId() == packet.getReceiveStreamId())
|| (packet.getSequenceNum()
<= ConnectionOptions.MIN_WINDOW_SIZE)) { // its in flight from the first batch
long oldId = con.getSendStreamId();
if (packet.isFlagSet(Packet.FLAG_SYNCHRONIZE)) {
if (oldId <= 0) {
// con fully established, w00t
con.setSendStreamId(packet.getReceiveStreamId());
} else if (oldId == packet.getReceiveStreamId()) {
// ok, as expected...
} else {
if (_log.shouldLog(Log.WARN))
_log.warn("Received a syn with the wrong IDs, con=" + con + " packet=" + packet);
sendReset(packet);
packet.releasePayload();
return;
}
}
try {
con.getPacketHandler().receivePacket(packet, con);
} catch (I2PException ie) {
if (_log.shouldLog(Log.ERROR))
_log.error("Received forged packet for " + con + "/" + oldId + ": " + packet, ie);
con.setSendStreamId(oldId);
}
} else if (packet.isFlagSet(Packet.FLAG_SYNCHRONIZE)) {
if (_log.shouldLog(Log.WARN))
_log.warn("Receive a syn packet with the wrong IDs, sending reset: " + packet);
sendReset(packet);
packet.releasePayload();
} else {
if (!con.getResetSent()) {
// someone is sending us a packet on the wrong stream
// It isn't a SYN so it isn't likely to have a FROM to send a reset back to
if (_log.shouldLog(Log.ERROR)) {
StringBuilder buf = new StringBuilder(512);
buf.append("Received a packet on the wrong stream: ");
buf.append(packet);
buf.append("\nthis connection:\n");
buf.append(con);
buf.append("\nall connections:");
for (Connection cur : _manager.listConnections()) {
buf.append('\n').append(cur);
}
_log.error(buf.toString(), new Exception("Wrong stream"));
}
}
packet.releasePayload();
}
}
}
}
/**
* Receive an incoming connection (built from a received SYN) Non-SYN packets with a zero
* SendStreamID may also be queued here so that they don't get thrown away while the SYN packet
* before it is queued.
*
* @param timeoutMs max amount of time to wait for a connection (if less than 1ms, wait
* indefinitely)
* @return connection received, or null if there was a timeout or the handler was shut down
*/
public Connection accept(long timeoutMs) {
if (_log.shouldLog(Log.DEBUG)) _log.debug("Accept(" + timeoutMs + ") called");
long expiration = timeoutMs + _context.clock().now();
while (true) {
if ((timeoutMs > 0) && (expiration < _context.clock().now())) return null;
if (!_active) {
// fail all the ones we had queued up
while (true) {
Packet packet = _synQueue.poll(); // fails immediately if empty
if (packet == null || packet.getOptionalDelay() == PoisonPacket.POISON_MAX_DELAY_REQUEST)
break;
sendReset(packet);
}
return null;
}
Packet syn = null;
while (_active && syn == null) {
if (_log.shouldLog(Log.DEBUG))
_log.debug(
"Accept(" + timeoutMs + "): active=" + _active + " queue: " + _synQueue.size());
if (timeoutMs <= 0) {
try {
syn = _synQueue.take(); // waits forever
} catch (InterruptedException ie) {
} // { break;}
} else {
long remaining = expiration - _context.clock().now();
// (dont think this applies anymore for LinkedBlockingQueue)
// BUGFIX
// The specified amount of real time has elapsed, more or less.
// If timeout is zero, however, then real time is not taken into consideration
// and the thread simply waits until notified.
if (remaining < 1) break;
try {
syn = _synQueue.poll(remaining, TimeUnit.MILLISECONDS); // waits the specified time max
} catch (InterruptedException ie) {
}
break;
}
}
if (syn != null) {
if (syn.getOptionalDelay() == PoisonPacket.POISON_MAX_DELAY_REQUEST) return null;
// deal with forged / invalid syn packets in _manager.receiveConnection()
// Handle both SYN and non-SYN packets in the queue
if (syn.isFlagSet(Packet.FLAG_SYNCHRONIZE)) {
// We are single-threaded here, so this is
// a good place to check for dup SYNs and drop them
Destination from = syn.getOptionalFrom();
if (from == null) {
if (_log.shouldLog(Log.WARN)) _log.warn("Dropping SYN packet with no FROM: " + syn);
// drop it
continue;
}
Connection oldcon = _manager.getConnectionByOutboundId(syn.getReceiveStreamId());
if (oldcon != null) {
// His ID not guaranteed to be unique to us, but probably is...
// only drop it on a destination match too
if (from.equals(oldcon.getRemotePeer())) {
if (_log.shouldLog(Log.WARN)) _log.warn("Dropping dup SYN: " + syn);
continue;
}
}
Connection con = _manager.receiveConnection(syn);
if (con != null) return con;
} else {
reReceivePacket(syn);
// ... and keep looping
}
}
// keep looping...
}
}
