_ Git - ldk-java/blob - src/main/java/org/ldk/batteries/NioPeerHandler.java

   1 package org.ldk.batteries;
   2
   3 import org.ldk.structs.*;
   4
   5 import java.io.IOException;
   6 import java.net.SocketAddress;
   7 import java.net.StandardSocketOptions;
   8 import java.nio.ByteBuffer;
   9 import java.nio.channels.*;
  10
  11 /**
  12  * A NioPeerHandler maps LDK's PeerHandler to Java's NIO I/O interface. It spawns a single background thread which
  13  * processes socket events and provides the data to LDK for decryption and processing.
  14  */
  15 public class NioPeerHandler {
  16     private static class Peer {
  17         SocketDescriptor descriptor;
  18         // When we are told by LDK to disconnect, we can't return to LDK until we are sure
  19         // won't call any more read/write PeerManager functions with the same connection.
  20         // This is set to true if we're in such a condition (with disconnect checked
  21         // before with the Peer monitor lock held) and false when we can return.
  22         boolean block_disconnect_socket = false;
  23         // Indicates LDK told us to disconnect this peer, and thus we should not call socket_disconnected.
  24         boolean disconnect_requested = false;
  25         SelectionKey key;
  26     }
  27
  28     // Android's java.nio implementation has a big lock inside the selector, preventing any concurrent access to it.
  29     // This appears to largely defeat the entire purpose of java.nio, but we work around it here by explicitly checking
  30     // for an Android environment and passing any selector access on any thread other than our internal one through
  31     // do_selector_action, which wakes up the selector before accessing it.
  32     private static boolean IS_ANDROID;
  33     static {
  34         IS_ANDROID = System.getProperty("java.vendor").toLowerCase().contains("android");
  35     }
  36     private boolean wakeup_selector = false;
  37     private interface SelectorCall {
  38         void meth() throws IOException;
  39     }
  40     private void do_selector_action(SelectorCall meth) throws IOException {
  41         if (IS_ANDROID) {
  42             wakeup_selector = true;
  43             this.selector.wakeup();
  44             synchronized (this.selector) {
  45                 meth.meth();
  46                 wakeup_selector = false;
  47             }
  48         } else {
  49             meth.meth();
  50         }
  51     }
  52
  53     private Peer setup_socket(SocketChannel chan) throws IOException {
  54         chan.configureBlocking(false);
  55         // Lightning tends to send a number of small messages back and forth between peers quickly, which Nagle is
  56         // particularly bad at handling, so we disable it here.
  57         chan.setOption(StandardSocketOptions.TCP_NODELAY, true);
  58         long our_id;
  59         synchronized (this) {
  60             this.socket_id = this.socket_id + 1;
  61             our_id = this.socket_id;
  62         }
  63
  64         final Peer peer = new Peer();
  65         SocketDescriptor descriptor = SocketDescriptor.new_impl(new SocketDescriptor.SocketDescriptorInterface() {
  66             @Override
  67             public long send_data(byte[] data, boolean resume_read) {
  68                 try {
  69                     if (resume_read) {
  70                         do_selector_action(() -> peer.key.interestOps(peer.key.interestOps() | SelectionKey.OP_READ));
  71                     }
  72                     long written = chan.write(ByteBuffer.wrap(data));
  73                     if (written != data.length) {
  74                         do_selector_action(() -> peer.key.interestOps(peer.key.interestOps() | SelectionKey.OP_WRITE));
  75                     }
  76                     return written;
  77                 } catch (IOException e) {
  78                     // Most likely the socket is disconnected, let the background thread handle it.
  79                     return 0;
  80                 }
  81             }
  82
  83             @Override
  84             public void disconnect_socket() {
  85                 synchronized (peer) {
  86                     peer.disconnect_requested = true;
  87                 }
  88                 try {
  89                     do_selector_action(() -> {
  90                         peer.key.cancel();
  91                         peer.key.channel().close();
  92                     });
  93                 } catch (IOException ignored) { }
  94                 synchronized (peer) {
  95                     while (peer.block_disconnect_socket) {
  96                         try {
  97                             peer.wait();
  98                         } catch (InterruptedException ignored) { }
  99                     }
 100                 }
 101             }
 102             @Override public boolean eq(SocketDescriptor other_arg) { return other_arg.hash() == our_id; }
 103             @Override public long hash() { return our_id; }
 104         });
 105         peer.descriptor = descriptor;
 106         return peer;
 107     }
 108
 109     PeerManager peer_manager;
 110     Thread io_thread;
 111     final Selector selector;
 112     long socket_id;
 113     volatile boolean shutdown = false;
 114
 115     /**
 116      * Constructs a new peer handler, spawning a thread to monitor for socket events.
 117      * The background thread will call the PeerManager's timer_tick_occured() function for you on an appropriate schedule.
 118      *
 119      * @param manager The LDK PeerManager which connection data will be provided to.
 120      * @throws IOException If an internal java.nio error occurs.
 121      */
 122     public NioPeerHandler(PeerManager manager) throws IOException {
 123         this.peer_manager = manager;
 124         this.selector = Selector.open();
 125         io_thread = new Thread(() -> {
 126             ByteBuffer buf = ByteBuffer.allocate(8192);
 127             long lastTimerTick = System.currentTimeMillis();
 128             while (true) {
 129                 try {
 130                     if (IS_ANDROID) {
 131                         while (true) {
 132                             synchronized (this.selector) {
 133                                 if (!wakeup_selector) {
 134                                     this.selector.select(1000);
 135                                     break;
 136                                 }
 137                             }
 138                         }
 139                     } else {
 140                         this.selector.select(1000);
 141                     }
 142                 } catch (IOException ignored) {
 143                     System.err.println("java.nio threw an unexpected IOException. Stopping PeerHandler thread!");
 144                     return;
 145                 }
 146                 if (shutdown) return;
 147                 if (Thread.interrupted()) return;
 148                 for (SelectionKey key : this.selector.selectedKeys()) {
 149                     try {
 150                         if ((key.interestOps() & SelectionKey.OP_ACCEPT) != 0) {
 151                             if (key.isAcceptable()) {
 152                                 SocketChannel chan;
 153                                 try {
 154                                     chan = ((ServerSocketChannel) key.channel()).accept();
 155                                 } catch (IOException ignored) {
 156                                     key.cancel();
 157                                     continue;
 158                                 }
 159                                 if (chan == null) continue;
 160                                 try {
 161                                     Peer peer = setup_socket(chan);
 162                                     Result_NonePeerHandleErrorZ res = this.peer_manager.new_inbound_connection(peer.descriptor);
 163                                     if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_OK) {
 164                                         peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer);
 165                                     }
 166                                 } catch (IOException ignored) { }
 167                             }
 168                             continue; // There is no attachment so the rest of the loop is useless
 169                         }
 170                         Peer peer = (Peer) key.attachment();
 171                         synchronized (peer) {
 172                             if (peer.disconnect_requested)
 173                                 continue;
 174                             peer.block_disconnect_socket = true;
 175                         }
 176                         try {
 177                             if (key.isValid() && (key.interestOps() & SelectionKey.OP_WRITE) != 0 && key.isWritable()) {
 178                                 Result_NonePeerHandleErrorZ res = this.peer_manager.write_buffer_space_avail(peer.descriptor);
 179                                 if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_Err) {
 180                                     key.channel().close();
 181                                     key.cancel();
 182                                 }
 183                             }
 184                             if (key.isValid() && (key.interestOps() & SelectionKey.OP_READ) != 0 && key.isReadable()) {
 185                                 buf.clear();
 186                                 int read = ((SocketChannel) key.channel()).read(buf);
 187                                 if (read == -1) {
 188                                     this.peer_manager.socket_disconnected(peer.descriptor);
 189                                     key.cancel();
 190                                 } else if (read > 0) {
 191                                     buf.flip();
 192                                     byte[] read_bytes = new byte[read];
 193                                     buf.get(read_bytes, 0, read);
 194                                     Result_boolPeerHandleErrorZ res = this.peer_manager.read_event(peer.descriptor, read_bytes);
 195                                     if (res instanceof Result_boolPeerHandleErrorZ.Result_boolPeerHandleErrorZ_OK) {
 196                                         if (((Result_boolPeerHandleErrorZ.Result_boolPeerHandleErrorZ_OK) res).res) {
 197                                             key.interestOps(key.interestOps() & (~SelectionKey.OP_READ));
 198                                         }
 199                                     } else {
 200                                         key.channel().close();
 201                                         key.cancel();
 202                                     }
 203                                 }
 204                             }
 205                         } catch (IOException ignored) {
 206                             try { key.channel().close(); } catch (IOException ignored2) { }
 207                             key.cancel();
 208                             peer_manager.socket_disconnected(peer.descriptor);
 209                         }
 210                         synchronized (peer) {
 211                             peer.block_disconnect_socket = false;
 212                             peer.notifyAll();
 213                         }
 214                     } catch (CancelledKeyException e) {
 215                         try { key.channel().close(); } catch (IOException ignored) { }
 216                         // The key is only cancelled when we have notified the PeerManager that the socket is closed, so
 217                         // no need to do anything here with the PeerManager.
 218                     }
 219                 }
 220                 if (lastTimerTick < System.currentTimeMillis() - 30 * 1000) {
 221                     peer_manager.timer_tick_occurred();
 222                     lastTimerTick = System.currentTimeMillis();
 223                 }
 224                 peer_manager.process_events();
 225             }
 226         }, "NioPeerHandler NIO Thread");
 227         io_thread.start();
 228     }
 229
 230     /**
 231      * Connect to a peer given their node id and socket address. Blocks until a connection is established (or returns
 232      * IOException) and then the connection handling runs in the background.
 233      *
 234      * @param their_node_id A valid 33-byte public key representing the peer's Lightning Node ID. If this is invalid,
 235      *                      undefined behavior (read: Segfault, etc) may occur.
 236      * @param remote The socket address to connect to.
 237      * @param timeout_ms The amount of time, in milliseconds, up to which we will wait for connection to complete.
 238      * @throws IOException If connecting to the remote endpoint fails or internal java.nio errors occur.
 239      */
 240     public void connect(byte[] their_node_id, SocketAddress remote, int timeout_ms) throws IOException {
 241         SocketChannel chan = SocketChannel.open();
 242         chan.configureBlocking(false);
 243         Selector open_selector = Selector.open();
 244         chan.register(open_selector, SelectionKey.OP_CONNECT);
 245         if (!chan.connect(remote)) {
 246             open_selector.select(timeout_ms);
 247         }
 248         if (!chan.finishConnect()) { // Note that this may throw its own IOException if we failed for another reason
 249             throw new IOException("Timed out");
 250         }
 251         Peer peer = setup_socket(chan);
 252         Result_CVec_u8ZPeerHandleErrorZ res = this.peer_manager.new_outbound_connection(their_node_id, peer.descriptor);
 253         if (res instanceof  Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) {
 254             byte[] initial_bytes = ((Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) res).res;
 255             if (chan.write(ByteBuffer.wrap(initial_bytes)) != initial_bytes.length) {
 256                 throw new IOException("We assume TCP socket buffer is at least a single packet in length");
 257             }
 258             do_selector_action(() -> peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer));
 259         } else {
 260             throw new IOException("LDK rejected outbound connection. This likely shouldn't ever happen.");
 261         }
 262     }
 263
 264     /**
 265      * Binds a listening socket to the given address, accepting incoming connections and handling them on the background
 266      * thread.
 267      *
 268      * @param socket_address The address to bind the listening socket to.
 269      * @throws IOException if binding the listening socket fail.
 270      */
 271     public void bind_listener(SocketAddress socket_address) throws IOException {
 272         ServerSocketChannel listen_channel = ServerSocketChannel.open();
 273         listen_channel.bind(socket_address);
 274         listen_channel.configureBlocking(false);
 275         do_selector_action(() -> listen_channel.register(this.selector, SelectionKey.OP_ACCEPT));
 276     }
 277
 278     /**
 279      * Interrupt the background thread, stopping all peer handling. Disconnection events to the PeerHandler are not made,
 280      * potentially leaving the PeerHandler in an inconsistent state.
 281      */
 282     public void interrupt() {
 283         shutdown = true;
 284         selector.wakeup();
 285         try {
 286             io_thread.join();
 287         } catch (InterruptedException ignored) { }
 288     }
 289
 290     /**
 291      * Calls process_events on the PeerManager immediately. Normally process_events is polled regularly to check for new
 292      * messages which need to be sent, but you can interrupt the poll and check immediately by calling this function.
 293      */
 294     public void check_events() {
 295         selector.wakeup();
 296     }
 297 }