ipdiscovery: adds custom port parameter

doc/lightning-listconfigs.7.md

@@ -90,6 +90,7 @@ On success, an object is returned, containing:
 - **disable-dns** (boolean, optional): `true` if `disable-dns` was set in config or cmdline
 - **disable-ip-discovery** (boolean, optional): `true` if `disable-ip-discovery` was set in config or cmdline **deprecated, removal in v23.11**
 - **announce-addr-discovered** (string, optional): `true`/`false`/`auto` depending on how `announce-addr-discovered` was set in config or cmdline *(added v23.02)*
+- **announce-addr-discovered-port** (integer, optional): Sets the announced TCP port for dynamically discovered IPs. *(added v23.02)*
 - **encrypted-hsm** (boolean, optional): `true` if `encrypted-hsm` was set in config or cmdline
 - **rpc-file-mode** (string, optional): `rpc-file-mode` field from config or cmdline, or default
 - **log-level** (string, optional): `log-level` field from config or cmdline, or default
@@ -221,4 +222,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:9953b3545acb82bed816b86a65ba51ff4b043d3848c4a3ae460aa68db1a4b542)
+[comment]: # ( SHA256STAMP:2f325aa6ef0506dc627409e3253c8627c49a7d1749ea9dbf24a5baa0fc8c307c)

doc/lightningd-config.5.md

@@ -368,6 +368,11 @@ use the RPC call lightning-setchannel(7).
   Note: You also need to open TCP port 9735 on your router towords your node.
   Note: Will always be disabled if you use 'always-use-proxy'.
 
+* **announce-addr-discovered-port**
+  Sets the public TCP port to use for announcing dynamically discovered IPs.
+  If unset, this defaults to the selected networks lightning port,
+  which is 9735 on mainnet.
+
 ### Lightning channel and HTLC options
 
 * **large-channels**

doc/schemas/listconfigs.schema.json

@@ -253,6 +253,11 @@
       "description": "`true`/`false`/`auto` depending on how `announce-addr-discovered` was set in config or cmdline",
       "added": "v23.02"
     },
+    "announce-addr-discovered-port": {
+      "type": "integer",
+      "description": "Sets the announced TCP port for dynamically discovered IPs.",
+      "added": "v23.02"
+    },
     "encrypted-hsm": {
       "type": "boolean",
       "description": "`true` if `encrypted-hsm` was set in config or cmdline"

lightningd/lightningd.h

@@ -62,6 +62,9 @@ struct config {
 	/* Excplicitly turns 'on' or 'off' IP discovery feature. */
 	enum opt_autobool ip_discovery;
 
+	/* Public TCP port assumed for IP discovery. Defaults to chainparams. */
+	u32 ip_discovery_port;
+
 	/* Minimal amount of effective funding_satoshis for accepting channels */
 	u64 min_capacity_sat;
 

lightningd/options.c

@@ -846,6 +846,9 @@ static const struct config testnet_config = {
 	/* Excplicitly turns 'on' or 'off' IP discovery feature. */
 	.ip_discovery = OPT_AUTOBOOL_AUTO,
 
+	/* Public TCP port assumed for IP discovery. Defaults to chainparams. */
+	.ip_discovery_port = 0,
+
 	/* Sets min_effective_htlc_capacity - at 1000$/BTC this is 10ct */
 	.min_capacity_sat = 10000,
 
@@ -912,6 +915,9 @@ static const struct config mainnet_config = {
 	/* Excplicitly turns 'on' or 'off' IP discovery feature. */
 	.ip_discovery = OPT_AUTOBOOL_AUTO,
 
+	/* Public TCP port assumed for IP discovery. Defaults to chainparams. */
+	.ip_discovery_port = 0,
+
 	/* Sets min_effective_htlc_capacity - at 1000$/BTC this is 10ct */
 	.min_capacity_sat = 10000,
 
@@ -1223,6 +1229,9 @@ static void register_opts(struct lightningd *ld)
 	opt_register_arg("--announce-addr-discovered", opt_set_autobool_arg, opt_show_autobool,
 			 &ld->config.ip_discovery,
 			 "Explicitly turns IP discovery 'on' or 'off'.");
+	opt_register_arg("--announce-addr-discovered-port", opt_set_uintval,
+			 opt_show_uintval, &ld->config.ip_discovery_port,
+			 "Sets the public TCP port to use for announcing discovered IPs.");
 
 	opt_register_noarg("--offline", opt_set_offline, ld,
 			   "Start in offline-mode (do not automatically reconnect and do not accept incoming connections)");
@@ -1427,6 +1436,9 @@ void handle_early_opts(struct lightningd *ld, int argc, char *argv[])
 	else
 		ld->config = mainnet_config;
 
+	/* Set the ln_port given from chainparams */
+	ld->config.ip_discovery_port = chainparams->ln_port;
+
 	/* Now we can initialize wallet_dsn */
 	ld->wallet_dsn = tal_fmt(ld, "sqlite3://%s/lightningd.sqlite3",
 				 ld->config_netdir);

lightningd/peer_control.c

@@ -1305,18 +1305,11 @@ static void update_remote_addr(struct lightningd *ld,
 			       const struct wireaddr *remote_addr,
 			       const struct node_id peer_id)
 {
-	u16 public_port;
-
 	/* failsafe to prevent privacy leakage. */
 	if (ld->always_use_proxy ||
 	    ld->config.ip_discovery == OPT_AUTOBOOL_FALSE)
 		return;
 
-	/* Peers will have likey reported our dynamic outbound TCP port.
-	 * Best guess is that we use default port for the selected network,
-	 * until we add a commandline switch to override this. */
-	public_port = chainparams_get_ln_port(chainparams);
-
 	switch (remote_addr->type) {
 	case ADDR_TYPE_IPV4:
 		/* init pointers first time */
@@ -1334,7 +1327,7 @@ static void update_remote_addr(struct lightningd *ld,
 		if (wireaddr_eq_without_port(ld->remote_addr_v4, remote_addr)) {
 			ld->discovered_ip_v4 = tal_dup(ld, struct wireaddr,
 						       ld->remote_addr_v4);
-			ld->discovered_ip_v4->port = public_port;
+			ld->discovered_ip_v4->port = ld->config.ip_discovery_port;
 			subd_send_msg(ld->gossip, towire_gossipd_discovered_ip(
 							  tmpctx,
 							  ld->discovered_ip_v4));
@@ -1357,7 +1350,7 @@ static void update_remote_addr(struct lightningd *ld,
 		if (wireaddr_eq_without_port(ld->remote_addr_v6, remote_addr)) {
 			ld->discovered_ip_v6 = tal_dup(ld, struct wireaddr,
 						       ld->remote_addr_v6);
-			ld->discovered_ip_v6->port = public_port;
+			ld->discovered_ip_v6->port = ld->config.ip_discovery_port;
 			subd_send_msg(ld->gossip, towire_gossipd_discovered_ip(
 							  tmpctx,
 							  ld->discovered_ip_v6));

tests/test_connection.py

@@ -188,6 +188,58 @@ def test_remote_addr_disabled(node_factory, bitcoind):
     assert not l2.daemon.is_in_log("Update our node_announcement for discovered address")
 
 
+@pytest.mark.developer("needs DEVELOPER=1 for fast gossip and --dev-allow-localhost for local remote_addr")
+def test_remote_addr_port(node_factory, bitcoind):
+    """Check address discovery (BOLT1 #917) can be done with non-default TCP ports
+       We perform logic tests on L2, setup same as above:
+         l1 --> [l2] <-- l3
+    """
+    port = 1234
+    opts = {'dev-allow-localhost': None,
+            'may_reconnect': True,
+            'dev-no-reconnect': None,
+            'announce-addr-discovered-port': port}
+    l1, l2, l3 = node_factory.get_nodes(3, opts=[opts, opts, opts])
+
+    # Disable announcing local autobind addresses with dev-allow-localhost.
+    # We need to have l2 opts 'bind-addr' to the (generated) value of 'addr'.
+    # So we stop, set 'bind-addr' option, delete 'addr' and restart first.
+    l2.stop()
+    l2.daemon.opts['bind-addr'] = l2.daemon.opts['addr']
+    del l2.daemon.opts['addr']
+    l2.start()
+    assert len(l2.rpc.getinfo()['address']) == 0
+
+    # l1->l2
+    l2.rpc.connect(l1.info['id'], 'localhost', l1.port)
+    l2.daemon.wait_for_log("Peer says it sees our address as: 127.0.0.1:[0-9]{5}")
+    l1.fundchannel(l2)
+    bitcoind.generate_block(5)
+    l1.daemon.wait_for_log(f"Received node_announcement for node {l2.info['id']}")
+    # l2->l3
+    l2.rpc.connect(l3.info['id'], 'localhost', l3.port)
+    l2.daemon.wait_for_log("Peer says it sees our address as: 127.0.0.1:[0-9]{5}")
+    l2.fundchannel(l3)
+    bitcoind.generate_block(5)
+
+    # restart both and wait for channels to be ready
+    l1.restart()
+    l2.rpc.connect(l1.info['id'], 'localhost', l1.port)
+    l2.daemon.wait_for_log("Already have funding locked in")
+    l3.restart()
+    l2.rpc.connect(l3.info['id'], 'localhost', l3.port)
+    l2.daemon.wait_for_log("Already have funding locked in")
+
+    # if ip discovery would have been enabled, we would have send an updated
+    # node_annoucement by now. Check we didn't...
+    assert l2.daemon.wait_for_log("Update our node_announcement for discovered address")
+    info = l2.rpc.getinfo()
+    assert len(info['address']) == 1
+    assert info['address'][0]['type'] == 'ipv4'
+    assert info['address'][0]['address'] == '127.0.0.1'
+    assert info['address'][0]['port'] == port
+
+
 def test_connect_standard_addr(node_factory):
     """Test standard node@host:port address
     """