opts: adds --announce-addr-discovered-port config option

This will give the user an option to set a custom port when using
discovered IPs for node_announcents. Without this, only the selected
networks default port can used.

Changelog-Added: Adds --announce-addr-discovered-port config option to set custom port for IP discovery.

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));