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.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.*;
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.
19 public class NioPeerHandler {
20 private static class Peer {
21 SocketDescriptor descriptor;
22 long descriptor_raw_pointer;
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;
32 IS_ANDROID = System.getProperty("java.vendor").toLowerCase().contains("android");
34 private boolean wakeup_selector = false;
35 private interface SelectorCall {
36 void meth() throws IOException;
38 private void do_selector_action(SelectorCall meth) throws IOException {
40 wakeup_selector = true;
41 this.selector.wakeup();
42 synchronized (this.selector) {
44 wakeup_selector = false;
51 static private Field CommonBasePointer;
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);
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);
71 this.socket_id = this.socket_id + 1;
72 our_id = this.socket_id;
75 final Peer peer = new Peer();
76 SocketDescriptor descriptor = SocketDescriptor.new_impl(new SocketDescriptor.SocketDescriptorInterface() {
78 public long send_data(byte[] data, boolean resume_read) {
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)));
89 } catch (IOException e) {
90 // Most likely the socket is disconnected, let the background thread handle it.
96 public void disconnect_socket() {
98 do_selector_action(() -> {
100 peer.key.channel().close();
102 } catch (IOException ignored) { }
104 @Override public boolean eq(SocketDescriptor other_arg) { return other_arg.hash() == our_id; }
105 @Override public long hash() { return our_id; }
107 peer.descriptor = descriptor;
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);
117 PeerManager peer_manager;
119 final Selector selector;
121 volatile boolean shutdown = false;
124 * Constructs a new peer handler, spawning a thread to monitor for socket events.
126 * @param manager The LDK PeerManager which connection data will be provided to.
127 * @throws IOException If an internal java.nio error occurs.
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);
137 long peer_manager_raw_pointer;
139 peer_manager_raw_pointer = CommonBasePointer.getLong(this.peer_manager);
140 } catch (IllegalAccessException e) {
141 throw new RuntimeException(e);
147 synchronized (this.selector) {
148 if (!wakeup_selector) {
149 this.selector.select(1000);
155 this.selector.select(1000);
157 } catch (IOException ignored) {
158 System.err.println("java.nio threw an unexpected IOException. Stopping PeerHandler thread!");
161 if (shutdown) return;
162 if (Thread.interrupted()) return;
163 for (SelectionKey key : this.selector.selectedKeys()) {
165 if ((key.interestOps() & SelectionKey.OP_ACCEPT) != 0) {
166 if (key.isAcceptable()) {
169 chan = ((ServerSocketChannel) key.channel()).accept();
170 } catch (IOException ignored) {
174 if (chan == null) continue;
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();
182 } catch (IOException ignored) { }
184 continue; // There is no attachment so the rest of the loop is useless
186 Peer peer = (Peer) key.attachment();
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();
195 if (key.isValid() && (key.interestOps() & SelectionKey.OP_READ) != 0 && key.isReadable()) {
196 ((Buffer)buf).clear();
197 int read = ((SocketChannel) key.channel()).read(buf);
199 this.peer_manager.socket_disconnected(peer.descriptor);
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.
212 if (read == BUF_SZ) {
213 read_bytes = max_buf_byte_object;
215 read_bytes = new byte[read];
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));
225 key.channel().close();
228 bindings.CResult_boolPeerHandleErrorZ_free(read_result_pointer);
231 } catch (IOException ignored) {
232 try { key.channel().close(); } catch (IOException ignored2) { }
234 peer_manager.socket_disconnected(peer.descriptor);
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.
242 peer_manager.process_events();
244 }, "NioPeerHandler NIO Thread");
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);
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.
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.
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);
273 if (!chan.finishConnect()) { // Note that this may throw its own IOException if we failed for another reason
274 throw new IOException("Timed out");
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");
287 peer.descriptor.disconnect_socket();
288 throw new IOException("LDK rejected outbound connection. This likely shouldn't ever happen.");
293 * Disconnects any connections currently open with the peer with the given node id.
295 * @param their_node_id must be a valid 33-byte public key
297 public void disconnect(byte[] their_node_id) {
298 this.peer_manager.disconnect_by_node_id(their_node_id, false);
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).
305 private LinkedList<ServerSocketChannel> listening_sockets = new LinkedList();
307 * Binds a listening socket to the given address, accepting incoming connections and handling them on the background
310 * @param socket_address The address to bind the listening socket to.
311 * @throws IOException if binding the listening socket fail.
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);
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.
328 public void interrupt() {
333 } catch (InterruptedException ignored) { }
334 synchronized(listening_sockets) {
337 for (ServerSocketChannel chan : listening_sockets) {
340 } catch (IOException ignored) {}
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.
348 public void check_events() {