lightningd: don't send other messages until we've received version.

This avoids subdaemons complaining about malformed messages from us, or doing the completely wrong thing, if they are really the wrong version. Signed-off-by: Rusty Russell <[email protected]>
ElementsProject · Apr 24, 2021 · f97a51c · f97a51c
1 parent 7b56b2b
commit f97a51c
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Showing 2 changed files with 15 additions and 1 deletion.
diff --git a/lightningd/subd.c b/lightningd/subd.c
@@ -419,6 +419,11 @@ static bool handle_version(struct subd *sd, const u8 *msg)
 		io_break(sd->ld);
 		return false;
 	}
+
+	sd->rcvd_version = true;
+	/* In case there are outgoing msgs, we can send now. */
+	msg_wake(sd->outq);
+
 	return true;
 }
 
@@ -605,10 +610,15 @@ static void destroy_subd(struct subd *sd)
 
 static struct io_plan *msg_send_next(struct io_conn *conn, struct subd *sd)
 {
-	const u8 *msg = msg_dequeue(sd->outq);
+	const u8 *msg;
 	int fd;
 
+	/* Don't send if we haven't read version! */
+	if (!sd->rcvd_version)
+		return msg_queue_wait(conn, sd->outq, msg_send_next, sd);
+
 	/* Nothing to do?  Wait for msg_enqueue. */
+	msg = msg_dequeue(sd->outq);
 	if (!msg)
 		return msg_queue_wait(conn, sd->outq, msg_send_next, sd);
 
@@ -702,6 +712,7 @@ static struct subd *new_subd(struct lightningd *ld,
 	tal_add_destructor(sd, destroy_subd);
 	list_head_init(&sd->reqs);
 	sd->channel = channel;
+	sd->rcvd_version = false;
 	if (node_id)
 		sd->node_id = tal_dup(sd, struct node_id, node_id);
 	else

diff --git a/lightningd/subd.h b/lightningd/subd.h
@@ -32,6 +32,9 @@ struct subd {
 	/* If we are associated with a single channel, this points to it. */
 	void *channel;
 
+	/* Have we received the version msg yet?  Don't send until we do. */
+	bool rcvd_version;
+
 	/* For logging */
 	struct log *log;
 	const struct node_id *node_id;