1 package org.ldk.batteries;
3 import org.ldk.impl.bindings;
4 import org.ldk.structs.*;
6 import java.io.IOException;
7 import java.net.SocketAddress;
8 import java.net.StandardSocketOptions;
9 import java.nio.ByteBuffer;
10 import java.nio.channels.SelectionKey;
11 import java.nio.channels.Selector;
12 import java.nio.channels.ServerSocketChannel;
13 import java.nio.channels.SocketChannel;
14 import java.util.concurrent.Callable;
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 // When we are told by LDK to disconnect, we can't return to LDK until we are sure
24 // won't call any more read/write PeerManager functions with the same connection.
25 // This is set to true if we're in such a condition (with disconnect checked
26 // before with the Peer monitor lock held) and false when we can return.
27 boolean block_disconnect_socket = false;
31 // Android's java.nio implementation has a big lock inside the selector, preventing any concurrent access to it.
32 // This appears to largely defeat the entire purpose of java.nio, but we work around it here by explicitly checking
33 // for an Android environment and passing any selector access on any thread other than our internal one through
34 // do_selector_action, which wakes up the selector before accessing it.
35 private static boolean IS_ANDROID;
37 IS_ANDROID = System.getProperty("java.vendor").toLowerCase().contains("android");
39 private boolean wakeup_selector = false;
40 private interface SelectorCall {
41 void meth() throws IOException;
43 private void do_selector_action(SelectorCall meth) throws IOException {
45 wakeup_selector = true;
46 this.selector.wakeup();
47 synchronized (this.selector) {
49 wakeup_selector = false;
56 private Peer setup_socket(SocketChannel chan) throws IOException {
57 chan.configureBlocking(false);
58 // Lightning tends to send a number of small messages back and forth between peers quickly, which Nagle is
59 // particularly bad at handling, so we disable it here.
60 chan.setOption(StandardSocketOptions.TCP_NODELAY, true);
63 this.socket_id = this.socket_id + 1;
64 our_id = this.socket_id;
67 final Peer peer = new Peer();
68 SocketDescriptor descriptor = SocketDescriptor.new_impl(new SocketDescriptor.SocketDescriptorInterface() {
70 public long send_data(byte[] data, boolean resume_read) {
73 do_selector_action(() -> peer.key.interestOps(peer.key.interestOps() | SelectionKey.OP_READ));
75 long written = chan.write(ByteBuffer.wrap(data));
76 if (written != data.length) {
77 do_selector_action(() -> peer.key.interestOps(peer.key.interestOps() | SelectionKey.OP_WRITE));
80 } catch (IOException e) {
81 // Most likely the socket is disconnected, let the background thread handle it.
87 public void disconnect_socket() {
89 do_selector_action(() -> {
91 peer.key.channel().close();
93 } catch (IOException ignored) { }
95 while (peer.block_disconnect_socket) {
98 } catch (InterruptedException ignored) { }
102 @Override public boolean eq(SocketDescriptor other_arg) { return other_arg.hash() == our_id; }
103 @Override public long hash() { return our_id; }
105 peer.descriptor = descriptor;
109 PeerManager peer_manager;
111 final Selector selector;
113 volatile boolean shutdown = false;
116 * Constructs a new peer handler, spawning a thread to monitor for socket events.
117 * The background thread will call the PeerManager's timer_tick_occured() function for you on an appropriate schedule.
119 * @param manager The LDK PeerManager which connection data will be provided to.
120 * @throws IOException If an internal java.nio error occurs.
122 public NioPeerHandler(PeerManager manager) throws IOException {
123 this.peer_manager = manager;
124 this.selector = Selector.open();
125 io_thread = new Thread(() -> {
126 ByteBuffer buf = ByteBuffer.allocate(8192);
127 long lastTimerTick = System.currentTimeMillis();
132 synchronized (this.selector) {
133 if (!wakeup_selector) {
134 this.selector.select(1000);
140 this.selector.select(1000);
142 } catch (IOException ignored) {
143 System.err.println("java.nio threw an unexpected IOException. Stopping PeerHandler thread!");
146 if (shutdown) return;
147 if (Thread.interrupted()) return;
148 for (SelectionKey key : this.selector.selectedKeys()) {
149 if ((key.interestOps() & SelectionKey.OP_ACCEPT) != 0) {
150 if (key.isAcceptable()) {
153 chan = ((ServerSocketChannel) key.channel()).accept();
154 } catch (IOException ignored) {
158 if (chan == null) continue;
160 Peer peer = setup_socket(chan);
161 Result_NonePeerHandleErrorZ res = this.peer_manager.new_inbound_connection(peer.descriptor);
162 if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_OK) {
163 peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer);
165 } catch (IOException ignored) { }
167 continue; // There is no attachment so the rest of the loop is useless
169 Peer peer = (Peer) key.attachment();
170 synchronized (peer) {
171 peer.block_disconnect_socket = true;
174 if (key.isValid() && (key.interestOps() & SelectionKey.OP_WRITE) != 0 && key.isWritable()) {
175 Result_NonePeerHandleErrorZ res = this.peer_manager.write_buffer_space_avail(peer.descriptor);
176 if (res instanceof Result_NonePeerHandleErrorZ.Result_NonePeerHandleErrorZ_Err) {
177 key.channel().close();
181 if (key.isValid() && (key.interestOps() & SelectionKey.OP_READ) != 0 && key.isReadable()) {
183 int read = ((SocketChannel) key.channel()).read(buf);
185 this.peer_manager.socket_disconnected(peer.descriptor);
187 } else if (read > 0) {
189 byte[] read_bytes = new byte[read];
190 buf.get(read_bytes, 0, read);
191 Result_boolPeerHandleErrorZ res = this.peer_manager.read_event(peer.descriptor, read_bytes);
192 if (res instanceof Result_boolPeerHandleErrorZ.Result_boolPeerHandleErrorZ_OK) {
193 if (((Result_boolPeerHandleErrorZ.Result_boolPeerHandleErrorZ_OK) res).res) {
194 key.interestOps(key.interestOps() & (~SelectionKey.OP_READ));
197 key.channel().close();
202 } catch (IOException ignored) {
203 try { key.channel().close(); } catch (IOException ignored2) { }
205 peer_manager.socket_disconnected(peer.descriptor);
207 synchronized (peer) {
208 peer.block_disconnect_socket = false;
212 if (lastTimerTick < System.currentTimeMillis() - 30 * 1000) {
213 peer_manager.timer_tick_occurred();
214 lastTimerTick = System.currentTimeMillis();
216 peer_manager.process_events();
218 }, "NioPeerHandler NIO Thread");
223 * Connect to a peer given their node id and socket address. Blocks until a connection is established (or returns
224 * IOException) and then the connection handling runs in the background.
226 * @param their_node_id A valid 33-byte public key representing the peer's Lightning Node ID. If this is invalid,
227 * undefined behavior (read: Segfault, etc) may occur.
228 * @param remote The socket address to connect to.
229 * @param timeout_ms The amount of time, in milliseconds, up to which we will wait for connection to complete.
230 * @throws IOException If connecting to the remote endpoint fails or internal java.nio errors occur.
232 public void connect(byte[] their_node_id, SocketAddress remote, int timeout_ms) throws IOException {
233 SocketChannel chan = SocketChannel.open();
234 chan.configureBlocking(false);
235 Selector open_selector = Selector.open();
236 chan.register(open_selector, SelectionKey.OP_CONNECT);
237 if (!chan.connect(remote)) {
238 open_selector.select(timeout_ms);
240 if (!chan.finishConnect()) { // Note that this may throw its own IOException if we failed for another reason
241 throw new IOException("Timed out");
243 Peer peer = setup_socket(chan);
244 Result_CVec_u8ZPeerHandleErrorZ res = this.peer_manager.new_outbound_connection(their_node_id, peer.descriptor);
245 if (res instanceof Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) {
246 byte[] initial_bytes = ((Result_CVec_u8ZPeerHandleErrorZ.Result_CVec_u8ZPeerHandleErrorZ_OK) res).res;
247 if (chan.write(ByteBuffer.wrap(initial_bytes)) != initial_bytes.length) {
248 throw new IOException("We assume TCP socket buffer is at least a single packet in length");
250 do_selector_action(() -> peer.key = chan.register(this.selector, SelectionKey.OP_READ, peer));
252 throw new IOException("LDK rejected outbound connection. This likely shouldn't ever happen.");
257 * Binds a listening socket to the given address, accepting incoming connections and handling them on the background
260 * @param socket_address The address to bind the listening socket to.
261 * @throws IOException if binding the listening socket fail.
263 public void bind_listener(SocketAddress socket_address) throws IOException {
264 ServerSocketChannel listen_channel = ServerSocketChannel.open();
265 listen_channel.bind(socket_address);
266 listen_channel.configureBlocking(false);
267 do_selector_action(() -> listen_channel.register(this.selector, SelectionKey.OP_ACCEPT));
271 * Interrupt the background thread, stopping all peer handling. Disconnection events to the PeerHandler are not made,
272 * potentially leaving the PeerHandler in an inconsistent state.
274 public void interrupt() {
279 } catch (InterruptedException ignored) { }
283 * Calls process_events on the PeerManager immediately. Normally process_events is polled regularly to check for new
284 * messages which need to be sent, but you can interrupt the poll and check immediately by calling this function.
286 public void check_events() {