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