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

   1 package org.ldk.batteries;
   2
   3 import org.ldk.impl.bindings;
   4 import org.ldk.structs.*;
   5
   6 import java.io.IOException;
   7 import java.lang.reflect.Field;
   8 import java.util.LinkedList;
   9 import java.net.SocketAddress;
  10 import java.net.StandardSocketOptions;
  11 import java.nio.Buffer;
  12 import java.nio.ByteBuffer;
  13 import java.nio.channels.*;
  14
  15 /**
  16  * A NioPeerHandler maps LDK's PeerHandler to Java's NIO I/O interface. It spawns a single background thread which
  17  * processes socket events and provides the data to LDK for decryption and processing.
  18  */
  19 public class NioPeerHandler {
  20     private static class Peer {
  21         SocketDescriptor descriptor;
  22         long descriptor_raw_pointer;
  23         SelectionKey key;
  24     }
  25
  26     // Android's java.nio implementation has a big lock inside the selector, preventing any concurrent access to it.
  27     // This appears to largely defeat the entire purpose of java.nio, but we work around it here by explicitly checking
  28     // for an Android environment and passing any selector access on any thread other than our internal one through
  29     // do_selector_action, which wakes up the selector before accessing it.
  30     private static boolean IS_ANDROID;
  31     static {
  32         IS_ANDROID = System.getProperty("java.vendor").toLowerCase().contains("android");
  33     }
  34     private boolean wakeup_selector = false;
  35     private interface SelectorCall {
  36         void meth() throws IOException;
  37     }
  38     private void do_selector_action(SelectorCall meth) throws IOException {
  39         if (IS_ANDROID) {
  40             wakeup_selector = true;
  41             this.selector.wakeup();
  42             synchronized (this.selector) {
  43                 meth.meth();
  44                 wakeup_selector = false;
  45             }
  46         } else {
  47             meth.meth();
  48         }
  49     }
  50
  51     static private Field CommonBasePointer;
  52     static {
  53         try {
  54             Class c = PeerManager.class.getSuperclass();
  55             CommonBasePointer = c.getDeclaredField("ptr");
  56             CommonBasePointer.setAccessible(true);
  57             long _dummy_check = CommonBasePointer.getLong(Ping.of((short)0, (short)0));
  58         } catch (NoSuchFieldException | IllegalAccessException e) {
  59             throw new IllegalArgumentException(
  60                     "We currently use reflection to access protected fields as Java has no reasonable access controls", e);
  61         }
  62     }
  63
  64     private Peer setup_socket(SocketChannel chan) throws IOException {
  65         chan.configureBlocking(false);
  66         // Lightning tends to send a number of small messages back and forth between peers quickly, which Nagle is
  67         // particularly bad at handling, so we disable it here.
  68         chan.setOption(StandardSocketOptions.TCP_NODELAY, true);
  69         long our_id;
  70         synchronized (this) {
  71             this.socket_id = this.socket_id + 1;
  72             our_id = this.socket_id;
  73         }
  74
  75         final Peer peer = new Peer();
  76         SocketDescriptor descriptor = SocketDescriptor.new_impl(new SocketDescriptor.SocketDescriptorInterface() {
  77             @Override
  78             public long send_data(byte[] data, boolean resume_read) {
  79                 try {
  80                     long written = chan.write(ByteBuffer.wrap(data));
  81                     if (written != data.length) {
  82                         do_selector_action(() -> peer.key.interestOps(
  83                                                         (peer.key.interestOps() | SelectionKey.OP_WRITE) & (~SelectionKey.OP_READ)));
  84                     } else if (resume_read) {
  85                         do_selector_action(() -> peer.key.interestOps(
  86                                                         (peer.key.interestOps() | SelectionKey.OP_READ) & (~SelectionKey.OP_WRITE)));
  87                                         }
  88                     return written;
  89                 } catch (IOException e) {
  90                     // Most likely the socket is disconnected, let the background thread handle it.
  91                     return 0;
  92                 }
  93             }
  94
  95             @Override
  96             public void disconnect_socket() {
  97                 try {
  98                     do_selector_action(() -> {
  99                         peer.key.cancel();
 100                         peer.key.channel().close();
 101                     });
 102                 } catch (IOException ignored) { }
 103             }
 104             @Override public boolean eq(SocketDescriptor other_arg) { return other_arg.hash() == our_id; }
 105             @Override public long hash() { return our_id; }
 106         });
 107         peer.descriptor = descriptor;
 108         try {
 109             peer.descriptor_raw_pointer = CommonBasePointer.getLong(descriptor);
 110         } catch (IllegalAccessException e) {
 111             throw new IllegalArgumentException(
 112                     "We currently use reflection to access protected fields as Java has no reasonable access controls", e);
 113         }
 114         return peer;
 115     }
 116
 117     PeerManager peer_manager;
 118     Thread io_thread;
 119     final Selector selector;
 120     long socket_id;
 121     volatile boolean shutdown = false;
 122
 123     /**
 124      * Constructs a new peer handler, spawning a thread to monitor for socket events.
 125      *
 126      * @param manager The LDK PeerManager which connection data will be provided to.
 127      * @throws IOException If an internal java.nio error occurs.
 128      */
 129     public NioPeerHandler(PeerManager manager) throws IOException {
 130         this.peer_manager = manager;
 131         this.selector = Selector.open();
 132         io_thread = new Thread(() -> {
 133             int BUF_SZ = 16 * 1024;
 134             byte[] max_buf_byte_object = new byte[BUF_SZ];
 135             ByteBuffer buf = ByteBuffer.allocate(BUF_SZ);
 136
 137             long peer_manager_raw_pointer;
 138             try {
 139                 peer_manager_raw_pointer = CommonBasePointer.getLong(this.peer_manager);
 140             } catch (IllegalAccessException e) {
 141                 throw new RuntimeException(e);
 142             }
 143             while (true) {
 144                 try {
 145                     if (IS_ANDROID) {
 146                         while (true) {
 147                             synchronized (this.selector) {
 148                                 if (!wakeup_selector) {
 149                                     this.selector.select(1000);
 150                                     break;
 151                                 }
 152                             }
 153                         }
 154                     } else {
 155                         this.selector.select(1000);
 156                     }
 157                 } catch (IOException ignored) {
 158                     System.err.println("java.nio threw an unexpected IOException. Stopping PeerHandler thread!");
 159                     return;
 160                 }
 161                 if (shutdown) return;
 162                 if (Thread.interrupted()) return;
 163                 for (SelectionKey key : this.selector.selectedKeys()) {
 164                     try {
 165                         if ((key.interestOps() & SelectionKey.OP_ACCEPT) != 0) {
 166                             if (key.isAcceptable()) {
 167                                 SocketChannel chan;
 168                                 try {
 169                                     chan = ((ServerSocketChannel) key.channel()).accept();
 170                                 } catch (IOException ignored) {
 171                                     key.cancel();
 172                                     continue;
 173                                 }
 174                                 if (chan == null) continue;
 175                                 try {
 176                                     Peer peer = setup_socket(chan);
 177                                     peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer);
 178                                     Result_NonePeerHandleErrorZ res = this.peer_manager.new_inbound_connection(peer.descriptor);
 179                                     if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_Err) {
 180                                                                                 peer.descriptor.disconnect_socket();
 181                                                                         }
 182                                 } catch (IOException ignored) { }
 183                             }
 184                             continue; // There is no attachment so the rest of the loop is useless
 185                         }
 186                         Peer peer = (Peer) key.attachment();
 187                         try {
 188                             if (key.isValid() && (key.interestOps() & SelectionKey.OP_WRITE) != 0 && key.isWritable()) {
 189                                 Result_NonePeerHandleErrorZ res = this.peer_manager.write_buffer_space_avail(peer.descriptor);
 190                                 if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_Err) {
 191                                     key.channel().close();
 192                                     key.cancel();
 193                                 }
 194                             }
 195                             if (key.isValid() && (key.interestOps() & SelectionKey.OP_READ) != 0 && key.isReadable()) {
 196                                 ((Buffer)buf).clear();
 197                                 int read = ((SocketChannel) key.channel()).read(buf);
 198                                 if (read == -1) {
 199                                     this.peer_manager.socket_disconnected(peer.descriptor);
 200                                     key.cancel();
 201                                 } else if (read > 0) {
 202                                     ((Buffer)buf).flip();
 203                                     // This code is quite hot during initial network graph sync, so we go a ways out of
 204                                     // our way to avoid object allocations that'll make the GC sweat later -
 205                                     // * when we're hot, we'll likely often be reading the full buffer, so we keep
 206                                     //   around a full-buffer-sized byte array to reuse across reads,
 207                                     // * We use the manual memory management call logic directly in bindings instead of
 208                                     //   the nice "human-readable" wrappers. This puts us at risk of memory issues,
 209                                     //   so we indirectly ensure compile fails if the types change by writing the
 210                                     //   "human-readable" form of the same code in the dummy function below.
 211                                     byte[] read_bytes;
 212                                     if (read == BUF_SZ) {
 213                                         read_bytes = max_buf_byte_object;
 214                                     } else {
 215                                         read_bytes = new byte[read];
 216                                     }
 217                                     buf.get(read_bytes, 0, read);
 218                                     long read_result_pointer = bindings.PeerManager_read_event(
 219                                             peer_manager_raw_pointer, peer.descriptor_raw_pointer, read_bytes);
 220                                     if (bindings.CResult_boolPeerHandleErrorZ_is_ok(read_result_pointer)) {
 221                                         if (bindings.LDKCResult_boolPeerHandleErrorZ_get_ok(read_result_pointer)) {
 222                                             key.interestOps(key.interestOps() & (~SelectionKey.OP_READ));
 223                                         }
 224                                     } else {
 225                                         key.channel().close();
 226                                         key.cancel();
 227                                     }
 228                                     bindings.CResult_boolPeerHandleErrorZ_free(read_result_pointer);
 229                                 }
 230                             }
 231                         } catch (IOException ignored) {
 232                             try { key.channel().close(); } catch (IOException ignored2) { }
 233                             key.cancel();
 234                             peer_manager.socket_disconnected(peer.descriptor);
 235                         }
 236                     } catch (CancelledKeyException e) {
 237                         try { key.channel().close(); } catch (IOException ignored) { }
 238                         // The key is only cancelled when we have notified the PeerManager that the socket is closed, so
 239                         // no need to do anything here with the PeerManager.
 240                     }
 241                 }
 242                 peer_manager.process_events();
 243             }
 244         }, "NioPeerHandler NIO Thread");
 245         io_thread.start();
 246     }
 247
 248     // Ensure the types used in the above manual code match what they were when the code was written.
 249     // Ensure the above manual bindings.* code changes if this fails to compile.
 250     private void dummy_check_return_type_matches_manual_memory_code_above(Peer peer) {
 251         byte[] read_bytes = new byte[32];
 252         Result_boolPeerHandleErrorZ res = this.peer_manager.read_event(peer.descriptor, read_bytes);
 253     }
 254
 255     /**
 256      * Connect to a peer given their node id and socket address. Blocks until a connection is established (or returns
 257      * IOException) and then the connection handling runs in the background.
 258      *
 259      * @param their_node_id A valid 33-byte public key representing the peer's Lightning Node ID. If this is invalid,
 260      *                      undefined behavior (read: Segfault, etc) may occur.
 261      * @param remote The socket address to connect to.
 262      * @param timeout_ms The amount of time, in milliseconds, up to which we will wait for connection to complete.
 263      * @throws IOException If connecting to the remote endpoint fails or internal java.nio errors occur.
 264      */
 265     public void connect(byte[] their_node_id, SocketAddress remote, int timeout_ms) throws IOException {
 266         SocketChannel chan = SocketChannel.open();
 267         chan.configureBlocking(false);
 268         Selector open_selector = Selector.open();
 269         chan.register(open_selector, SelectionKey.OP_CONNECT);
 270         if (!chan.connect(remote)) {
 271             open_selector.select(timeout_ms);
 272         }
 273         if (!chan.finishConnect()) { // Note that this may throw its own IOException if we failed for another reason
 274             throw new IOException("Timed out");
 275         }
 276         Peer peer = setup_socket(chan);
 277         do_selector_action(() -> peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer));
 278         Result_CVec_u8ZPeerHandleErrorZ res = this.peer_manager.new_outbound_connection(their_node_id, peer.descriptor);
 279         if (res instanceof  Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) {
 280             byte[] initial_bytes = ((Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) res).res;
 281             if (chan.write(ByteBuffer.wrap(initial_bytes)) != initial_bytes.length) {
 282                 peer.descriptor.disconnect_socket();
 283                 this.peer_manager.socket_disconnected(peer.descriptor);
 284                 throw new IOException("We assume TCP socket buffer is at least a single packet in length");
 285             }
 286         } else {
 287             peer.descriptor.disconnect_socket();
 288             throw new IOException("LDK rejected outbound connection. This likely shouldn't ever happen.");
 289         }
 290     }
 291
 292     /**
 293      * Disconnects any connections currently open with the peer with the given node id.
 294      *
 295      * @param their_node_id must be a valid 33-byte public key
 296      */
 297     public void disconnect(byte[] their_node_id) {
 298         this.peer_manager.disconnect_by_node_id(their_node_id, false);
 299     }
 300
 301     /**
 302      * Before shutdown, we have to ensure all of our listening sockets are closed manually, as they appear
 303      * to otherwise remain open and lying around on OSX (though no other platform).
 304      */
 305     private LinkedList<ServerSocketChannel> listening_sockets = new LinkedList();
 306     /**
 307      * Binds a listening socket to the given address, accepting incoming connections and handling them on the background
 308      * thread.
 309      *
 310      * @param socket_address The address to bind the listening socket to.
 311      * @throws IOException if binding the listening socket fail.
 312      */
 313     public void bind_listener(SocketAddress socket_address) throws IOException {
 314         ServerSocketChannel listen_channel = ServerSocketChannel.open();
 315         listen_channel.setOption(StandardSocketOptions.SO_REUSEADDR, true);
 316         listen_channel.bind(socket_address);
 317         listen_channel.configureBlocking(false);
 318         do_selector_action(() -> listen_channel.register(this.selector, SelectionKey.OP_ACCEPT));
 319         synchronized(listening_sockets) {
 320             listening_sockets.add(listen_channel);
 321         }
 322     }
 323
 324     /**
 325      * Interrupt the background thread, stopping all peer handling. Disconnection events to the PeerHandler are not made,
 326      * potentially leaving the PeerHandler in an inconsistent state.
 327      */
 328     public void interrupt() {
 329         shutdown = true;
 330         selector.wakeup();
 331         try {
 332             io_thread.join();
 333         } catch (InterruptedException ignored) { }
 334         synchronized(listening_sockets) {
 335             try {
 336                 selector.close();
 337                 for (ServerSocketChannel chan : listening_sockets) {
 338                     chan.close();
 339                 }
 340             } catch (IOException ignored) {}
 341         }
 342     }
 343
 344     /**
 345      * Calls process_events on the PeerManager immediately. Normally process_events is polled regularly to check for new
 346      * messages which need to be sent, but you can interrupt the poll and check immediately by calling this function.
 347      */
 348     public void check_events() {
 349         selector.wakeup();
 350     }
 351 }