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