connectd: Pass the init_featurebits down to connectd and use in init

The `init_featurebits` are computed at startup, and then cached
indefinitely. They are then used whenever a new `init` handshake is performed.

We could add a new message to push updates to `connectd` whenever a plugin is
added or removed, but that's up for discussion.

connectd/connect_wire.csv

@@ -15,6 +15,8 @@ msgdata,connectctl_init,dev_allow_localhost,bool,
 msgdata,connectctl_init,use_dns,bool,
 msgdata,connectctl_init,tor_password,wirestring,
 msgdata,connectctl_init,use_v3_autotor,bool,
+msgdata,connectctl_init,init_featurebits_len,u16,
+msgdata,connectctl_init,init_featurebits,u8,init_featurebits_len
 
 # Connectd->master, here are the addresses I bound, can announce.
 msgtype,connectctl_init_reply,2100

connectd/connectd.c

@@ -154,6 +154,9 @@ struct daemon {
 
 	/* Allow to define the default behavior of tor services calls*/
 	bool use_v3_autotor;
+
+	/* featurebits that we support internally, and via plugins */
+	u8 *init_featurebits;
 };
 
 /* Peers we're trying to reach: we iterate through addrs until we succeed
@@ -472,7 +475,8 @@ static struct io_plan *handshake_in_success(struct io_conn *conn,
 	struct node_id id;
 	node_id_from_pubkey(&id, id_key);
 	status_peer_debug(&id, "Connect IN");
-	return peer_exchange_initmsg(conn, daemon, cs, &id, addr);
+	return peer_exchange_initmsg(conn, daemon, cs, &id, addr,
+				     daemon->init_featurebits);
 }
 
 /*~ When we get a connection in we set up its network address then call
@@ -532,7 +536,8 @@ static struct io_plan *handshake_out_success(struct io_conn *conn,
 	node_id_from_pubkey(&id, key);
 	connect->connstate = "Exchanging init messages";
 	status_peer_debug(&id, "Connect OUT");
-	return peer_exchange_initmsg(conn, connect->daemon, cs, &id, addr);
+	return peer_exchange_initmsg(conn, connect->daemon, cs, &id, addr,
+				     connect->daemon->init_featurebits);
 }
 
 struct io_plan *connection_out(struct io_conn *conn, struct connecting *connect)
@@ -1210,7 +1215,7 @@ static struct io_plan *connect_init(struct io_conn *conn,
 		&proxyaddr, &daemon->use_proxy_always,
 		&daemon->dev_allow_localhost, &daemon->use_dns,
 		&tor_password,
-		&daemon->use_v3_autotor)) {
+		&daemon->use_v3_autotor, &daemon->init_featurebits)) {
 		/* This is a helper which prints the type expected and the actual
 		 * message, then exits (it should never be called!). */
 		master_badmsg(WIRE_CONNECTCTL_INIT, msg);

connectd/peer_exchange_initmsg.c

@@ -155,7 +155,8 @@ struct io_plan *peer_exchange_initmsg(struct io_conn *conn,
 				      struct daemon *daemon,
 				      const struct crypto_state *cs,
 				      const struct node_id *id,
-				      const struct wireaddr_internal *addr)
+				      const struct wireaddr_internal *addr,
+				      const u8 *init_featurebits)
 {
 	/* If conn is closed, forget peer */
 	struct peer *peer = tal(conn, struct peer);
@@ -200,7 +201,7 @@ struct io_plan *peer_exchange_initmsg(struct io_conn *conn,
 	 * from now on they'll all go in initfeatures. */
 	peer->msg = towire_init(NULL,
 				get_offered_globalinitfeatures(tmpctx),
-				get_offered_initfeatures(tmpctx),
+				init_featurebits,
 				tlvs);
 	status_peer_io(LOG_IO_OUT, &peer->id, peer->msg);
 	peer->msg = cryptomsg_encrypt_msg(peer, &peer->cs, take(peer->msg));

connectd/peer_exchange_initmsg.h

@@ -1,6 +1,7 @@
 #ifndef LIGHTNING_CONNECTD_PEER_EXCHANGE_INITMSG_H
 #define LIGHTNING_CONNECTD_PEER_EXCHANGE_INITMSG_H
 #include "config.h"
+#include <ccan/short_types/short_types.h>
 
 struct crypto_state;
 struct daemon;
@@ -13,6 +14,7 @@ struct io_plan *peer_exchange_initmsg(struct io_conn *conn,
 				      struct daemon *daemon,
 				      const struct crypto_state *cs,
 				      const struct node_id *id,
-				      const struct wireaddr_internal *addr);
+				      const struct wireaddr_internal *addr,
+				      const u8 *init_featurebits);
 
 #endif /* LIGHTNING_CONNECTD_PEER_EXCHANGE_INITMSG_H */

lightningd/connect_control.c

@@ -337,7 +337,7 @@ static void connect_init_done(struct subd *connectd,
 int connectd_init(struct lightningd *ld)
 {
 	int fds[2];
-	u8 *msg;
+	u8 *msg, *init_features;
 	int hsmfd;
 	struct wireaddr_internal *wireaddrs = ld->proposed_wireaddr;
 	enum addr_listen_announce *listen_announce = ld->proposed_listen_announce;
@@ -362,6 +362,12 @@ int connectd_init(struct lightningd *ld)
 		*listen_announce = ADDR_LISTEN_AND_ANNOUNCE;
 	}
 
+	init_features =
+	    featurebits_or(tmpctx,
+			   take(plugins_collect_featurebits(
+			       tmpctx, ld->plugins, PLUGIN_FEATURES_INIT)),
+			   take(get_offered_initfeatures(tmpctx)));
+
 	msg = towire_connectctl_init(
 	    tmpctx, chainparams,
 	    &ld->id,
@@ -370,7 +376,7 @@ int connectd_init(struct lightningd *ld)
 	    ld->proxyaddr, ld->use_proxy_always || ld->pure_tor_setup,
 	    IFDEV(ld->dev_allow_localhost, false), ld->config.use_dns,
 	    ld->tor_service_password ? ld->tor_service_password : "",
-	    ld->config.use_v3_autotor);
+	    ld->config.use_v3_autotor, init_features);
 
 	subd_req(ld->connectd, ld->connectd, take(msg), -1, 0,
 		 connect_init_done, NULL);