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