From 4901136cfe2e50e66b3e999c1fbcec5e618ba4b5 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Wed, 5 May 2021 02:47:42 +0000
Subject: [PATCH] Broadcast node_announcements regularly.

---
 README.md   |  6 +++++-
 src/cli.rs  | 35 +++++++++++++++++++++++++++++++++--
 src/main.rs | 22 +++++++++++++++++++++-
 3 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 5dda263..5b42054 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ git clone git@github.com:lightningdevkit/ldk-sample.git
 ## Usage
 ```
 cd ldk-sample
-cargo run <bitcoind-rpc-username>:<bitcoind-rpc-password>@<bitcoind-rpc-host>:<bitcoind-rpc-port> <ldk_storage_directory_path> [<ldk-peer-listening-port>] [bitcoin-network]
+cargo run <bitcoind-rpc-username>:<bitcoind-rpc-password>@<bitcoind-rpc-host>:<bitcoind-rpc-port> <ldk_storage_directory_path> [<ldk-peer-listening-port>] [bitcoin-network] [announced-listen-addr announced-node-name]
 ```
 `bitcoind`'s RPC username and password likely can be found through `cat ~/.bitcoin/.cookie`.
 
@@ -17,6 +17,10 @@ cargo run <bitcoind-rpc-username>:<bitcoind-rpc-password>@<bitcoind-rpc-host>:<b
 
 `ldk-peer-listening-port`: defaults to 9735.
 
+`announced-listen-addr` and `announced-node-name`: default to nothing, disabling any public announcements of this node.
+`announced-listen-addr` can be set to an IPv4 or IPv6 address to announce that as a publicly-connectable address for this node.
+`announced-node-name` can be any string up to 32 bytes in length, representing this node's alias.
+
 ## License
 
 Licensed under either:
diff --git a/src/cli.rs b/src/cli.rs
index 34987a8..f762fe5 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -9,6 +9,7 @@ use bitcoin::secp256k1::key::PublicKey;
 use lightning::chain;
 use lightning::chain::keysinterface::KeysManager;
 use lightning::ln::features::InvoiceFeatures;
+use lightning::ln::msgs::NetAddress;
 use lightning::ln::{PaymentHash, PaymentSecret};
 use lightning::routing::network_graph::NetGraphMsgHandler;
 use lightning::routing::router;
@@ -18,7 +19,7 @@ use lightning_invoice::{utils, Currency, Invoice};
 use std::env;
 use std::io;
 use std::io::{BufRead, Write};
-use std::net::{SocketAddr, ToSocketAddrs};
+use std::net::{IpAddr, SocketAddr, ToSocketAddrs};
 use std::ops::Deref;
 use std::path::Path;
 use std::str::FromStr;
@@ -33,12 +34,14 @@ pub(crate) struct LdkUserInfo {
 	pub(crate) bitcoind_rpc_host: String,
 	pub(crate) ldk_storage_dir_path: String,
 	pub(crate) ldk_peer_listening_port: u16,
+	pub(crate) ldk_announced_listen_addr: Option<NetAddress>,
+	pub(crate) ldk_announced_node_name: [u8; 32],
 	pub(crate) network: Network,
 }
 
 pub(crate) fn parse_startup_args() -> Result<LdkUserInfo, ()> {
 	if env::args().len() < 3 {
-		println!("ldk-tutorial-node requires 3 arguments: `cargo run <bitcoind-rpc-username>:<bitcoind-rpc-password>@<bitcoind-rpc-host>:<bitcoind-rpc-port> ldk_storage_directory_path [<ldk-incoming-peer-listening-port>] [bitcoin-network]`");
+		println!("ldk-tutorial-node requires 3 arguments: `cargo run <bitcoind-rpc-username>:<bitcoind-rpc-password>@<bitcoind-rpc-host>:<bitcoind-rpc-port> ldk_storage_directory_path [<ldk-incoming-peer-listening-port>] [bitcoin-network] [announced-listen-addr announced-node-name]`");
 		return Err(());
 	}
 	let bitcoind_rpc_info = env::args().skip(1).next().unwrap();
@@ -84,6 +87,32 @@ pub(crate) fn parse_startup_args() -> Result<LdkUserInfo, ()> {
 		Some(_) => panic!("Unsupported network provided. Options are: `regtest`, `testnet`"),
 		None => Network::Testnet,
 	};
+
+	let ldk_announced_listen_addr = match env::args().skip(arg_idx + 1).next().as_ref() {
+		Some(s) => match IpAddr::from_str(s) {
+			Ok(IpAddr::V4(a)) => {
+				Some(NetAddress::IPv4 { addr: a.octets(), port: ldk_peer_listening_port })
+			}
+			Ok(IpAddr::V6(a)) => {
+				Some(NetAddress::IPv6 { addr: a.octets(), port: ldk_peer_listening_port })
+			}
+			Err(_) => panic!("Failed to parse announced-listen-addr into an IP address"),
+		},
+		None => None,
+	};
+
+	let ldk_announced_node_name = match env::args().skip(arg_idx + 2).next().as_ref() {
+		Some(s) => {
+			if s.len() > 32 {
+				panic!("Node Alias can not be longer than 32 bytes");
+			}
+			let mut bytes = [0; 32];
+			bytes[..s.len()].copy_from_slice(s.as_bytes());
+			bytes
+		}
+		None => [0; 32],
+	};
+
 	Ok(LdkUserInfo {
 		bitcoind_rpc_username,
 		bitcoind_rpc_password,
@@ -91,6 +120,8 @@ pub(crate) fn parse_startup_args() -> Result<LdkUserInfo, ()> {
 		bitcoind_rpc_port,
 		ldk_storage_dir_path,
 		ldk_peer_listening_port,
+		ldk_announced_listen_addr,
+		ldk_announced_node_name,
 		network,
 	})
 }
diff --git a/src/main.rs b/src/main.rs
index f51528b..31fb84e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -577,6 +577,26 @@ async fn start_ldk() {
 		Err(e) => println!("ERROR: errored reading channel peer info from disk: {:?}", e),
 	}
 
+	// Regularly broadcast our node_announcement. This is only required (or possible) if we have
+	// some public channels, and is only useful if we have public listen address(es) to announce.
+	// In a production environment, this should occur only after the announcement of new channels
+	// to avoid churn in the global network graph.
+	let chan_manager = Arc::clone(&channel_manager);
+	let network = args.network;
+	if args.ldk_announced_listen_addr.is_some() {
+		tokio::spawn(async move {
+			let mut interval = tokio::time::interval(Duration::from_secs(60));
+			loop {
+				interval.tick().await;
+				chan_manager.broadcast_node_announcement(
+					[0; 3],
+					args.ldk_announced_node_name,
+					vec![args.ldk_announced_listen_addr.as_ref().unwrap().clone()],
+				);
+			}
+		});
+	}
+
 	// Start the CLI.
 	cli::poll_for_user_input(
 		peer_manager.clone(),
@@ -588,7 +608,7 @@ async fn start_ldk() {
 		event_ntfn_sender,
 		ldk_data_dir.clone(),
 		logger.clone(),
-		args.network,
+		network,
 	)
 	.await;
 }
-- 
2.39.5