lightningd/subdaemon: keep peer pointer for one-per-peer daemons.

This is really useful to map daemon back to peer.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/gossip_control.c

@@ -132,7 +132,7 @@ static enum subdaemon_status gossip_status(struct subdaemon *gossip,
 
 void gossip_init(struct lightningd *ld)
 {
-	ld->gossip = new_subdaemon(ld, ld, "lightningd_gossip",
+	ld->gossip = new_subdaemon(ld, ld, "lightningd_gossip", NULL,
 				   gossip_status_wire_type_name,
 				   gossip_control_wire_type_name,
 				   gossip_status, gossip_finished, -1);

lightningd/hsm_control.c

@@ -77,7 +77,7 @@ void hsm_init(struct lightningd *ld, bool newdir)
 {
 	bool create;
 
-	ld->hsm = new_subdaemon(ld, ld, "lightningd_hsm",
+	ld->hsm = new_subdaemon(ld, ld, "lightningd_hsm", NULL,
 				hsm_status_wire_type_name,
 				hsm_control_wire_type_name,
 				hsm_status, hsm_finished, -1);

lightningd/peer_control.c

@@ -162,8 +162,8 @@ static void peer_got_handshake_hsmfd(struct subdaemon *hsm, const u8 *msg,
 	}
 
 	/* Give handshake daemon the hsm fd. */
-	peer->owner = new_subdaemon(peer, peer->ld,
-				    "lightningd_handshake",
+	peer->owner = new_subdaemon(peer->ld, peer->ld,
+				    "lightningd_handshake", peer,
 				    handshake_status_wire_type_name,
 				    handshake_control_wire_type_name,
 				    NULL, NULL,
@@ -178,10 +178,6 @@ static void peer_got_handshake_hsmfd(struct subdaemon *hsm, const u8 *msg,
 	/* Peer struct longer owns fd. */
 	peer->fd = -1;
 
-	/* Now handshake owns peer: until it succeeds, peer vanishes
-	 * when it does. */
-	tal_steal(peer->owner, peer);
-
 	if (peer->id) {
 		req = towire_handshake_initiator_req(peer, &peer->ld->dstate.id,
 						     peer->id);
@@ -767,8 +763,8 @@ void peer_accept_open(struct peer *peer,
 	}
 
 	peer_set_condition(peer, "Starting opening daemon");
-	peer->owner = new_subdaemon(peer, ld,
-				    "lightningd_opening",
+	peer->owner = new_subdaemon(ld, ld,
+				    "lightningd_opening", peer,
 				    opening_status_wire_type_name,
 				    opening_control_wire_type_name,
 				    NULL, NULL,
@@ -780,7 +776,6 @@ void peer_accept_open(struct peer *peer,
 		tal_free(peer);
 		return;
 	}
-	tal_steal(peer->owner, peer);
 	/* We handed off peer fd */
 	peer->fd = -1;
 
@@ -831,8 +826,8 @@ static void gossip_peer_released(struct subdaemon *gossip,
 		      id, fc->peer->unique_id);
 
 	peer_set_condition(fc->peer, "Starting opening daemon");
-	fc->peer->owner = new_subdaemon(fc->peer, ld,
-					"lightningd_opening",
+	fc->peer->owner = new_subdaemon(fc->peer->ld, ld,
+					"lightningd_opening", fc->peer,
 					opening_status_wire_type_name,
 					opening_control_wire_type_name,
 					NULL, NULL,
@@ -841,15 +836,12 @@ static void gossip_peer_released(struct subdaemon *gossip,
 		log_unusual(ld->log, "Could not subdaemon opening: %s",
 			    strerror(errno));
 		peer_set_condition(fc->peer, "Failed to subdaemon opening");
-		tal_free(fc);
+		tal_free(fc->peer);
 		return;
 	}
 	/* They took our fd. */
 	fc->peer->fd = -1;
 
-	/* fc only lasts as long as this daemon does, for now. */
-	tal_steal(fc->peer->owner, fc);
-
 	channel_config(ld, &ours,
 		       &max_to_self_delay, &max_minimum_depth,
 		       &min_effective_htlc_capacity_msat);

lightningd/subdaemon.c

@@ -269,6 +269,7 @@ static void destroy_subdaemon(struct subdaemon *sd)
 struct subdaemon *new_subdaemon(const tal_t *ctx,
 				struct lightningd *ld,
 				const char *name,
+				struct peer *peer,
 				const char *(*statusname)(int status),
 				const char *(*reqname)(int req),
 				enum subdaemon_status (*statuscb)
@@ -312,6 +313,7 @@ struct subdaemon *new_subdaemon(const tal_t *ctx,
 	log_info(sd->log, "pid %u, statusfd %i, reqfd %i",
 		 sd->pid, status_fd, req_fd);
 
+	sd->peer = tal_steal(sd, peer);
 	return sd;
 }
 

lightningd/subdaemon.h

@@ -26,6 +26,9 @@ struct subdaemon {
 	/* Connection for requests if any (write, then read) */
 	struct io_conn *req_conn;
 
+	/* If we are associated with a single peer, this points to it. */
+	struct peer *peer;
+
 	/* For logging */
 	struct log *log;
 
@@ -48,6 +51,7 @@ struct subdaemon {
  * @ctx: context to allocate from
  * @ld: global state
  * @name: basename of daemon
+ * @peer: peer to take ownership of if non-NULL;
  * @statusname: function to get name from status messages
  * @reqname: function to get name from request messages, or NULL if no requests.
  * @statuscb: function to call when status message received (or NULL)
@@ -57,10 +61,13 @@ struct subdaemon {
  * @statuscb is called with fd == -1 when a status message is
  * received; if it returns STATUS_NEED_FD, we read an fd from the
  * daemon and call it again with that as the third arg.
+ *
+ * If this succeeds subdaemon owns @peer.
  */
 struct subdaemon *new_subdaemon(const tal_t *ctx,
 				struct lightningd *ld,
 				const char *name,
+				struct peer *peer,
 				const char *(*statusname)(int status),
 				const char *(*reqname)(int req),
 				enum subdaemon_status (*statuscb)