gossipd: neaten insert_broadcast a little.

Suggested-by: @cdecker.

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

gossipd/broadcast.c

@@ -63,7 +63,7 @@ void insert_broadcast_nostore(struct broadcast_state *bstate,
 
 void insert_broadcast(struct broadcast_state **bstate,
 		      const u8 *msg,
-		      const struct amount_sat *channel_announce_sat,
+		      const u8 *addendum,
 		      struct broadcastable *bcast)
 {
 	u32 offset;
@@ -73,7 +73,7 @@ void insert_broadcast(struct broadcast_state **bstate,
 		u64 idx;
 
 		bcast->index = idx = gossip_store_add((*bstate)->gs, msg,
-						      channel_announce_sat);
+						      addendum);
 		if (!idx)
 			status_failed(STATUS_FAIL_INTERNAL_ERROR,
 				      "Could not add to gossip store: %s",

gossipd/broadcast.h

@@ -39,11 +39,12 @@ struct broadcast_state *new_broadcast_state(struct routing_state *rstate,
 /* Append a queued message for broadcast.  Must be explicitly deleted.
  * Also adds it to the gossip store.
  *
- * If it's a channel_announcement, channel_announce_sat must be set.
+ * If it's a channel_announcement, caller sets addendum to the
+ * WIRE_GOSSIP_STORE_CHANNEL_AMOUNT to immediately follow the announcement.
  */
 void insert_broadcast(struct broadcast_state **bstate,
 		      const u8 *msg,
-		      const struct amount_sat *channel_announce_sat,
+		      const u8 *addendum,
 		      struct broadcastable *bcast);
 
 /* Add to broadcast, but not store: for gossip store compaction. */

gossipd/gossip_store.c

@@ -201,33 +201,6 @@ struct gossip_store *gossip_store_new(struct routing_state *rstate)
 	return gs;
 }
 
-/**
- * Wrap the raw gossip message and write it to fd
- *
- * @param fd File descriptor to write the wrapped message into
- * @param gossip_msg The message to write
- * @param channel_announce_sat Amount iff gossip_msg is a channel_announcement
- * @param lenp The length to increase by amount written.
- * @return true if the message was written
- */
-static bool gossip_store_append(int fd,
-				const u8 *gossip_msg,
-				const struct amount_sat *channel_announce_sat,
-				u64 *lenp)
-{
-	if (!append_msg(fd, gossip_msg, lenp))
-		return false;
-
-	if (fromwire_peektype(gossip_msg) == WIRE_CHANNEL_ANNOUNCEMENT) {
-		/* This gives the channel amount. */
-		u8 *msg = towire_gossip_store_channel_amount(tmpctx,
-						     *channel_announce_sat);
-		if (!append_msg(fd, msg, lenp))
-			return false;
-	}
-	return true;
-}
-
 /* Copy a whole message from one gossip_store to another.  Returns
  * total msg length including header, or 0 on error. */
 static size_t copy_message(int in_fd, int out_fd, unsigned offset)
@@ -294,7 +267,7 @@ static bool add_local_unnannounced(int in_fd, int out_fd,
 
 		msg = towire_gossipd_local_add_channel(tmpctx, &c->scid,
 						       &peer->id, c->sat);
-		if (!gossip_store_append(out_fd, msg, NULL, len))
+		if (!append_msg(out_fd, msg, len))
 			return false;
 
 		for (size_t i = 0; i < 2; i++) {
@@ -495,19 +468,23 @@ bool gossip_store_maybe_compact(struct gossip_store *gs,
 }
 
 u64 gossip_store_add(struct gossip_store *gs, const u8 *gossip_msg,
-		     const struct amount_sat *channel_announce_sat)
+		     const u8 *addendum)
 {
 	u64 off = gs->len;
 
 	/* Should never get here during loading! */
 	assert(gs->writable);
 
-	if (!gossip_store_append(gs->fd, gossip_msg, channel_announce_sat,
-				 &gs->len)) {
+	if (!append_msg(gs->fd, gossip_msg, &gs->len)) {
 		status_broken("Failed writing to gossip store: %s",
 			      strerror(errno));
 		return 0;
 	}
+	if (addendum && !append_msg(gs->fd, addendum, &gs->len)) {
+		status_broken("Failed writing addendum to gossip store: %s",
+			      strerror(errno));
+		return 0;
+	}
 
 	gs->count++;
 	return off;
@@ -521,7 +498,7 @@ void gossip_store_add_channel_delete(struct gossip_store *gs,
 	/* Should never get here during loading! */
 	assert(gs->writable);
 
-	if (!gossip_store_append(gs->fd, msg, NULL, &gs->len))
+	if (!append_msg(gs->fd, msg, &gs->len))
 		status_failed(STATUS_FAIL_INTERNAL_ERROR,
 			      "Failed writing channel_delete to gossip store: %s",
 			      strerror(errno));

gossipd/gossip_store.h

@@ -27,10 +27,11 @@ struct gossip_store *gossip_store_new(struct routing_state *rstate);
 void gossip_store_load(struct routing_state *rstate, struct gossip_store *gs);
 
 /**
- * Add a gossip message to the gossip_store
+ * Add a gossip message to the gossip_store (and optional addendum)
  */
 u64 gossip_store_add(struct gossip_store *gs, const u8 *gossip_msg,
-		     const struct amount_sat *channel_announce_sat);
+		     const u8 *addendum);
+
 
 /**
  * Remember that we deleted a channel as a result of its outpoint being spent

gossipd/routing.c

@@ -14,6 +14,7 @@
 #include <common/wire_error.h>
 #include <common/wireaddr.h>
 #include <gossipd/gen_gossip_peerd_wire.h>
+#include <gossipd/gen_gossip_store.h>
 #include <gossipd/gen_gossip_wire.h>
 #include <inttypes.h>
 #include <wire/gen_peer_wire.h>
@@ -1334,10 +1335,12 @@ static void add_channel_announce_to_broadcast(struct routing_state *rstate,
 					      u32 timestamp,
 					      u32 index)
 {
+	u8 *addendum = towire_gossip_store_channel_amount(tmpctx, chan->sat);
+
 	chan->bcast.timestamp = timestamp;
 	/* 0, unless we're loading from store */
 	chan->bcast.index = index;
-	insert_broadcast(&rstate->broadcasts, channel_announce, &chan->sat,
+	insert_broadcast(&rstate->broadcasts, channel_announce, addendum,
 			 &chan->bcast);
 	rstate->local_channel_announced |= is_local_channel(rstate, chan);
 }