TLS transport wiring: full-session TLS over the Presents NIO stream

Wraps the entire client<->server TCP object stream in TLS, strictly opt-in via
an injected SSLContext (null = byte-for-byte the original plaintext behavior).

Connection: a ByteChannel _ioChannel indirection (defaults to the raw socket;
a TLS-wrapping channel when enabled). Selector registration, connection-pending
checks and close still use the raw SocketChannel.

Server (PresentsConnectionManager/PresentsConnection/ConnectionManager):
setSSLContext/isTlsEnabled; accepted sockets are wrapped in a non-blocking
ServerTlsChannel after init+registration; reads/writes route through the io
channel. tls-channel NeedsWrite/NeedsRead on write are treated as partial writes
(stashed in the existing per-connection overflow queue, retried each timed-select
tick — the server never needed OP_WRITE); on read, NeedsRead stays OP_READ and
NeedsWrite adds OP_WRITE so the re-dispatch pumps the handshake flush, cleared
after a clean read. processAuthedConnections carries the established io channel
from the authing connection to the running connection (init() would otherwise
revert it to the raw socket mid-session).

Client (Client/BlockingCommunicator): Client.setSSLContext; the connected
blocking socket is wrapped in a ClientTlsChannel (handshake driven transparently
in blocking mode); the Reader/Writer threads share it (one-unwrap + one-wrap, the
concurrency tls-channel allows).

DatagramChannelReader: fails closed — refuses to bind datagram ports while TLS is
enabled (we have no DTLS, so plaintext datagrams alongside TLS would be a footgun;
Bang binds zero datagram ports, so this never triggers today).

core/src/main/java/com/threerings/nio/conman/Connection.java

@@ -9,6 +9,7 @@ import static com.threerings.NaryaLog.log;
 
 import java.io.IOException;
 import java.net.InetAddress;
+import java.nio.channels.ByteChannel;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
 
@@ -33,6 +34,9 @@ public abstract class Connection implements NetEventHandler
     {
         _cmgr = cmgr;
         _channel = channel;
+        // by default we do plaintext I/O directly on the raw socket channel; if TLS is enabled
+        // a TLS-wrapping ByteChannel will be installed via setIoChannel() before any I/O happens
+        _ioChannel = channel;
         _lastEvent = createStamp;
         _connectionId = ++_lastConnectionId;
     }
@@ -53,6 +57,26 @@ public abstract class Connection implements NetEventHandler
         return _channel;
     }
 
+    /**
+     * Returns the byte channel through which application data should be read and written. This is
+     * the raw socket channel for plaintext connections, or a TLS-wrapping channel when TLS is
+     * enabled. Selector registration, connection-pending checks and close still operate on the raw
+     * {@link #getChannel} socket channel.
+     */
+    public ByteChannel getIoChannel ()
+    {
+        return _ioChannel;
+    }
+
+    /**
+     * Installs the byte channel through which application data is read and written. Used to wrap
+     * the raw socket channel with a TLS channel when TLS is enabled.
+     */
+    public void setIoChannel (ByteChannel ioChannel)
+    {
+        _ioChannel = ioChannel;
+    }
+
     /**
      * Returns the address associated with this connection or null if it has no underlying socket
      * channel.
@@ -163,6 +187,16 @@ public abstract class Connection implements NetEventHandler
         }
 
         log.debug("Closing channel " + this + ".");
+        // if we wrapped the raw socket in a TLS channel, close it first (best effort) so it can
+        // emit its close_notify; closing the raw channel afterward is idempotent
+        if (_ioChannel != null && _ioChannel != _channel) {
+            try {
+                _ioChannel.close();
+            } catch (IOException ioe) {
+                // best effort; we're tearing down anyway
+            }
+        }
+        _ioChannel = null;
         try {
             _channel.close();
         } catch (IOException ioe) {
@@ -176,6 +210,10 @@ public abstract class Connection implements NetEventHandler
     protected ConnectionManager _cmgr;
     protected SocketChannel _channel;
 
+    /** The channel through which we do application I/O. Defaults to {@link #_channel} (plaintext);
+     * replaced with a TLS-wrapping channel when TLS is enabled. */
+    protected ByteChannel _ioChannel;
+
     protected long _lastEvent;
 
     protected int _connectionId;

core/src/main/java/com/threerings/nio/conman/ConnectionManager.java

@@ -29,6 +29,9 @@ import com.samskivert.util.Tuple;
 
 import com.threerings.nio.SelectorIterable;
 
+import tlschannel.NeedsReadException;
+import tlschannel.NeedsWriteException;
+
 import static com.threerings.NaryaLog.log;
 
 /**
@@ -378,8 +381,10 @@ public abstract class ConnectionManager extends LoopingThread
                 return false;
             }
 
-            // then write the data to the socket
+            // then write the data to the io channel (the raw socket for plaintext connections, or
-            int wrote = sochan.write(_outbuf);
+            // the TLS-wrapping channel when TLS is enabled); the connection-pending guard above
+            // still uses the raw socket channel
+            int wrote = conn.getIoChannel().write(_outbuf);
             noteWrite(1, wrote);
 
             // if we didn't write our entire message, deal with the leftover bytes
@@ -388,6 +393,18 @@ public abstract class ConnectionManager extends LoopingThread
                 pwh.handlePartialWrite(conn, _outbuf);
             }
 
+        } catch (NeedsWriteException nwe) {
+            // the TLS layer couldn't flush all its bytes to the socket right now; treat this just
+            // like a partial write and stash the remainder in the overflow queue for the next tick
+            fully = false;
+            pwh.handlePartialWrite(conn, _outbuf);
+
+        } catch (NeedsReadException nre) {
+            // the TLS layer needs inbound bytes (handshake) before it can write; treat as a partial
+            // write. OP_READ is always set so the inbound data will arrive and the next tick retries
+            fully = false;
+            pwh.handlePartialWrite(conn, _outbuf);
+
         } catch (NotYetConnectedException nyce) {
             // this should be caught by isConnectionPending() but awesomely it's not
             pwh.handlePartialWrite(conn, _outbuf);
@@ -537,8 +554,18 @@ public abstract class ConnectionManager extends LoopingThread
                     return false; // not ready to write to this connection yet
                 }
 
-                // write all we can of our partial buffer
+                // write all we can of our partial buffer through the io channel (raw socket for
-                int wrote = sochan.write(_partial);
+                // plaintext, TLS-wrapping channel when TLS is enabled)
+                int wrote;
+                try {
+                    wrote = conn.getIoChannel().write(_partial);
+                } catch (NeedsWriteException nwe) {
+                    // TLS can't flush right now; leave the partial for the next tick
+                    return false;
+                } catch (NeedsReadException nre) {
+                    // TLS needs inbound handshake bytes first; leave the partial for the next tick
+                    return false;
+                }
                 noteWrite(0, wrote);
 
                 if (_partial.remaining() == 0) {

core/src/main/java/com/threerings/presents/client/BlockingCommunicator.java

@@ -14,6 +14,7 @@ import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
 import java.nio.channels.AsynchronousCloseException;
+import java.nio.channels.ByteChannel;
 import java.nio.channels.DatagramChannel;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.Selector;
@@ -22,6 +23,8 @@ import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.PublicKey;
 
+import javax.net.ssl.SSLContext;
+
 import com.samskivert.util.LoopingThread;
 import com.samskivert.util.Queue;
 import com.samskivert.util.StringUtil;
@@ -289,6 +292,17 @@ public class BlockingCommunicator extends Communicator
         if (_channel != null) {
             log.debug("Closing socket channel.");
 
+            // if we wrapped the socket in a TLS channel, close it first (best effort) so it can
+            // emit its close_notify; closing the raw channel afterward is idempotent
+            if (_ioChannel != null && _ioChannel != _channel) {
+                try {
+                    _ioChannel.close();
+                } catch (IOException ioe) {
+                    // best effort; we're tearing down anyway
+                }
+            }
+            _ioChannel = null;
+
             try {
                 _channel.close();
             } catch (IOException ioe) {
@@ -407,7 +421,9 @@ public class BlockingCommunicator extends Communicator
     protected int writeMessage (ByteBuffer buf)
         throws IOException
     {
-        return _channel.write(buf);
+        // write through the io channel: the raw socket for plaintext, or the TLS channel when TLS
+        // is enabled. In blocking mode the TLS channel drives the handshake and blocks transparently
+        return _ioChannel.write(buf);
     }
 
     /**
@@ -502,7 +518,9 @@ public class BlockingCommunicator extends Communicator
     protected boolean readFrame ()
         throws IOException
     {
-        return _fin.readFrame(_channel);
+        // read through the io channel: the raw socket for plaintext, or the TLS channel when TLS is
+        // enabled (which decrypts and drives the handshake transparently in blocking mode)
+        return _fin.readFrame(_ioChannel);
     }
 
     /**
@@ -664,6 +682,18 @@ public class BlockingCommunicator extends Communicator
             _channel.configureBlocking(true);
             _channel.socket().setKeepAlive(true);
 
+            // if a TLS context was injected, wrap the connected (blocking) socket in a client TLS
+            // channel; the handshake is driven transparently on the first read/write. Otherwise we
+            // do plaintext I/O directly on the raw socket, exactly as before. Both the Reader and
+            // Writer threads use this same instance: the reader only reads and the writer only
+            // writes, which is the one-unwrap + one-wrap concurrency that tls-channel allows.
+            SSLContext sslContext = _client.getSSLContext();
+            if (sslContext != null) {
+                _ioChannel = tlschannel.ClientTlsChannel.newBuilder(_channel, sslContext).build();
+            } else {
+                _ioChannel = _channel;
+            }
+
             // our messages are framed (preceded by their length), so we use these helper streams
             // to manage the framing
             _fin = new FramedInputStream();
@@ -1008,6 +1038,11 @@ public class BlockingCommunicator extends Communicator
     protected DatagramWriter _datagramWriter;
 
     protected SocketChannel _channel;
+
+    /** The channel through which we do application I/O: the raw {@link #_channel} for plaintext, or
+     * a TLS-wrapping channel when TLS is enabled. Shared by the reader and writer threads. */
+    protected ByteChannel _ioChannel;
+
     protected Queue<UpstreamMessage> _msgq = new Queue<UpstreamMessage>();
 
     protected Selector _selector;

core/src/main/java/com/threerings/presents/client/Client.java

@@ -8,6 +8,8 @@ package com.threerings.presents.client;
 import java.security.PublicKey;
 import java.util.HashSet;
 
+import javax.net.ssl.SSLContext;
+
 import com.google.common.collect.Sets;
 
 import com.samskivert.util.Interval;
@@ -220,6 +222,26 @@ public class Client
         return key == null ? false : setPublicKey(SecureUtil.stringToRSAPublicKey(key));
     }
 
+    /**
+     * Returns the {@link SSLContext} used to wrap the connection to the server in full-session TLS,
+     * or null if TLS is not enabled.
+     */
+    public SSLContext getSSLContext ()
+    {
+        return _sslContext;
+    }
+
+    /**
+     * Sets the {@link SSLContext} used to wrap the entire connection to the server in TLS. When set
+     * (non-null), the communicator wraps its socket in a client TLS channel before authenticating;
+     * when null (the default) the connection remains plaintext and behaves exactly as before. TLS
+     * is strictly opt-in. This must be set before any call to <code>logon</code>.
+     */
+    public void setSSLContext (SSLContext ctx)
+    {
+        _sslContext = ctx;
+    }
+
     /**
      * Sets if we require a secure authentication.
      */
@@ -1061,6 +1083,9 @@ public class Client
     /** Our public key. */
     protected PublicKey _publicKey;
 
+    /** The TLS context used to wrap our connection to the server, or null if TLS is disabled. */
+    protected SSLContext _sslContext;
+
     /** Our session secret key. */
     protected byte[] _secret;
 

core/src/main/java/com/threerings/presents/server/net/DatagramChannelReader.java

@@ -42,6 +42,17 @@ public class DatagramChannelReader
 
     public void bind()
     {
+        // fail closed: we have no DTLS, so binding datagram ports while the TCP session is
+        // TLS-encrypted would silently send these datagrams in plaintext, defeating the point of
+        // TLS. Refuse to bind rather than create that footgun. (Bang passes zero datagram ports, so
+        // this guard never triggers today; it prevents a future regression.)
+        if (_datagramPorts.length > 0 && _conMan.isTlsEnabled()) {
+            log.error("Refusing to bind datagram ports while TLS is enabled: UDP datagrams are " +
+                      "not encrypted (no DTLS) and must not run alongside the encrypted TLS " +
+                      "session.", "ports", _datagramPorts.length);
+            return;
+        }
+
         for (int port : _datagramPorts) {
             try {
                 acceptDatagrams(port);

core/src/main/java/com/threerings/presents/server/net/PresentsConnection.java

@@ -12,7 +12,9 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
+import java.nio.channels.ByteChannel;
 import java.nio.channels.DatagramChannel;
+import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
@@ -30,6 +32,9 @@ import com.threerings.presents.util.DatagramSequencer;
 import com.threerings.nio.conman.Connection;
 import com.threerings.nio.conman.ConnectionManager;
 
+import tlschannel.NeedsReadException;
+import tlschannel.NeedsWriteException;
+
 import static com.threerings.presents.Log.log;
 
 /**
@@ -207,9 +212,14 @@ public class PresentsConnection extends Connection
                 }
             }
 
+            // read frames through the io channel: the raw socket for plaintext connections, or the
+            // TLS-wrapping channel when TLS is enabled (which decrypts and drives the handshake)
+            ByteChannel ioChannel = getIoChannel();
+            boolean tls = (ioChannel != _channel);
+
             // there may be more than one frame in the buffer, so we keep reading them until we run
             // out of data
-            while (_fin.readFrame(_channel)) {
+            while (_fin.readFrame(ioChannel)) {
                 // make a note of how many bytes are in this frame (including the frame length
                 // bytes which aren't reported in available())
                 bytesIn = _fin.available() + 4;
@@ -220,6 +230,28 @@ public class PresentsConnection extends Connection
                 _handler.handleMessage(msg);
             }
 
+            // we read all we could without the TLS layer asking us to write; if we previously set
+            // OP_WRITE to flush a pending handshake write, clear it again so we don't spin (OP_READ
+            // always stays set). No-op for plaintext connections, which never touch OP_WRITE.
+            if (tls && selkey != null && (selkey.interestOps() & SelectionKey.OP_WRITE) != 0) {
+                selkey.interestOps(selkey.interestOps() & ~SelectionKey.OP_WRITE);
+            }
+
+        } catch (NeedsReadException nre) {
+            // the TLS layer has no complete frame for us yet (or the handshake needs more inbound
+            // bytes); stop reading this turn. The key stays OP_READ so the next readable event
+            // resumes us. Return whatever whole frames we managed to read above.
+            return bytesIn;
+
+        } catch (NeedsWriteException nwe) {
+            // the TLS layer needs to write (handshake) but the socket isn't writable right now; add
+            // OP_WRITE interest so handleEvent is re-invoked when writable (processIncomingEvents
+            // dispatches on any ready key), at which point our read pump flushes the handshake write
+            if (selkey != null) {
+                selkey.interestOps(selkey.interestOps() | SelectionKey.OP_WRITE);
+            }
+            return bytesIn;
+
         } catch (EOFException eofe) {
             // close down the socket gracefully
             close();

core/src/main/java/com/threerings/presents/server/net/PresentsConnectionManager.java

@@ -17,6 +17,8 @@ import java.nio.channels.SocketChannel;
 
 import java.security.PrivateKey;
 
+import javax.net.ssl.SSLContext;
+
 import com.google.common.collect.Lists;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -193,6 +195,34 @@ public class PresentsConnectionManager extends ConnectionManager
         return _privateKey;
     }
 
+    /**
+     * Sets the {@link SSLContext} used to wrap accepted client connections in full-session TLS. If
+     * this is null (the default) connections remain plaintext and behave exactly as before; TLS is
+     * strictly opt-in. This must be set before the connection manager starts accepting sockets.
+     */
+    public void setSSLContext (SSLContext ctx)
+    {
+        _sslContext = ctx;
+    }
+
+    /**
+     * Returns the {@link SSLContext} used to wrap accepted connections in TLS, or null if TLS is
+     * not enabled.
+     */
+    public SSLContext getSSLContext ()
+    {
+        return _sslContext;
+    }
+
+    /**
+     * Returns true if full-session TLS is enabled on this connection manager (i.e. an
+     * {@link SSLContext} has been injected).
+     */
+    public boolean isTlsEnabled ()
+    {
+        return _sslContext != null;
+    }
+
     /**
      * Called when a datagram message is ready to be read off its channel.
      */
@@ -475,7 +505,25 @@ public class PresentsConnectionManager extends ConnectionManager
     @Override
     protected void handleAcceptedSocket (SocketChannel channel)
     {
-        handleAcceptedSocket(channel, new AuthingConnection());
+        AuthingConnection conn = new AuthingConnection();
+        // the super implementation configures the channel non-blocking, inits the connection and
+        // registers it for OP_READ; afterwards the connection's io channel is the raw socket
+        handleAcceptedSocket(channel, conn);
+
+        // if TLS is enabled, wrap the (now non-blocking) raw channel in a server-side TLS channel
+        // and install it as the connection's io channel before any read or write happens. This
+        // must happen here, after init+registration, so the AuthingConnection's very first frame is
+        // read through the TLS channel and the handshake is driven transparently
+        if (_sslContext != null && !conn.isClosed()) {
+            try {
+                tlschannel.ServerTlsChannel tlsChannel =
+                    tlschannel.ServerTlsChannel.newBuilder(channel, _sslContext).build();
+                conn.setIoChannel(tlsChannel);
+            } catch (Exception e) {
+                log.warning("Failed to wrap accepted socket in TLS", "channel", channel, e);
+                conn.close();
+            }
+        }
     }
 
     /**
@@ -493,6 +541,12 @@ public class PresentsConnectionManager extends ConnectionManager
                 rconn.init(this, conn.getChannel(), iterStamp);
                 rconn.selkey = conn.selkey;
 
+                // carry over the io channel from the authing connection: if TLS is enabled this is
+                // the TLS channel with an established session, and the running connection must keep
+                // using it rather than reverting to the raw (plaintext) socket that init() defaults
+                // to. For plaintext connections this is just the raw socket channel (a no-op).
+                rconn.setIoChannel(conn.getIoChannel());
+
                 // we need to keep using the same object input and output streams from the
                 // beginning of the session because they have context that needs to be preserved
                 rconn.inheritStreams(conn);
@@ -607,6 +661,9 @@ public class PresentsConnectionManager extends ConnectionManager
     protected List<ChainedAuthenticator> _authors = Lists.newArrayList();
     protected PrivateKey _privateKey;
 
+    /** The TLS context used to wrap accepted connections, or null if TLS is disabled. */
+    protected SSLContext _sslContext;
+
     protected Queue<AuthingConnection> _authq = Queue.newQueue();
     protected Queue<Tuple<Connection, InetSocketAddress>> _connectq = Queue.newQueue();