gossmap: add callback for gossipd to see dying messages.

diff --git a/common/gossmap.c b/common/gossmap.c
index d0bb948f..45ea204b 100644
--- a/common/gossmap.c
+++ b/common/gossmap.c
@@ -641,8 +641,47 @@ static void node_announcement(struct gossmap *map, u64 nann_off)
 		n->nann_off = nann_off;
 }
 
+static bool report_dying_cb(struct gossmap *map,
+			    u64 dying_off,
+			    u16 msglen,
+			    void (*dyingcb)(struct short_channel_id scid,
+					    u32 blockheight,
+					    u64 offset,
+					    void *cb_arg),
+			    void *cb_arg)
+{
+	struct short_channel_id scid;
+	u32 blockheight;
+	u8 *msg;
+
+	msg = tal_arr(NULL, u8, msglen);
+	map_copy(map, dying_off, msg, msglen);
+
+	if (!fromwire_gossip_store_chan_dying(msg, &scid, &blockheight)) {
+		map->logcb(map->cbarg,
+			   LOG_BROKEN,
+			   "Invalid chan_dying message @%"PRIu64
+			   "/%"PRIu64": %s",
+			   dying_off, map->map_size, msglen,
+			   tal_hex(tmpctx, msg));
+		tal_free(msg);
+		return false;
+	}
+	tal_free(msg);
+
+	dyingcb(scid, blockheight, dying_off, cb_arg);
+	return true;
+}
+
 /* Mutual recursion */
-static bool map_catchup(struct gossmap *map, bool must_be_clean, bool *changed);
+static bool map_catchup(struct gossmap *map,
+			void (*dyingcb)(struct short_channel_id scid,
+					u32 blockheight,
+					u64 offset,
+					void *cb_arg),
+			void *cb_arg,
+			bool must_be_clean,
+			bool *changed);
 
 static void init_map_structs(struct gossmap *map)
 {
@@ -724,7 +763,7 @@ static bool reopen_store(struct gossmap *map, u64 ended_off)
 	map->generation++;
 
 	/* Now do reload. */
-	map_catchup(map, false, &changed);
+	map_catchup(map, NULL, NULL, false, &changed);
 	return changed;
 }
 
@@ -744,7 +783,14 @@ static bool csum_matches(const struct gossmap *map,
 }
 
 /* Returns false only if must_be_clean is true. */
-static bool map_catchup(struct gossmap *map, bool must_be_clean, bool *changed)
+static bool map_catchup(struct gossmap *map,
+			void (*dyingcb)(struct short_channel_id scid,
+					u32 blockheight,
+					u64 offset,
+					void *cb_arg),
+			void *cb_arg,
+			bool must_be_clean,
+			bool *changed)
 {
 	size_t reclen, num_bad_cupdates = 0;
 
@@ -830,6 +876,8 @@ static bool map_catchup(struct gossmap *map, bool must_be_clean, bool *changed)
 			/* We absorbed this in add_channel; ignore */
 			continue;
 		} else if (type == WIRE_GOSSIP_STORE_CHAN_DYING) {
+			if (dyingcb && !report_dying_cb(map, off, msglen, dyingcb, cb_arg))
+				return false;
 			/* We don't really care until it's deleted */
 			continue;
 		} else if (type == WIRE_GOSSIP_STORE_UUID) {
@@ -856,7 +904,13 @@ static bool map_catchup(struct gossmap *map, bool must_be_clean, bool *changed)
 	return true;
 }
 
-static bool load_gossip_store(struct gossmap *map, bool must_be_clean)
+static bool load_gossip_store(struct gossmap *map,
+			      void (*dyingcb)(struct short_channel_id scid,
+					      u32 blockheight,
+					      u64 offset,
+					      void *cb_arg),
+			      void *cb_arg,
+			      bool must_be_clean)
 {
 	bool updated;
 
@@ -880,7 +934,7 @@ static bool load_gossip_store(struct gossmap *map, bool must_be_clean)
 	init_map_structs(map);
 
 	map->map_end = 1;
-	return map_catchup(map, must_be_clean, &updated);
+	return map_catchup(map, dyingcb, cb_arg, must_be_clean, &updated);
 }
 
 static void destroy_map(struct gossmap *map)
@@ -1292,7 +1346,7 @@ bool gossmap_refresh(struct gossmap *map)
 		}
 	}
 
-	map_catchup(map, false, &changed);
+	map_catchup(map, NULL, NULL, false, &changed);
 	return changed;
 }
 
@@ -1319,7 +1373,11 @@ struct gossmap *gossmap_load_(const tal_t *ctx,
 					    enum log_level level,
 					    const char *fmt,
 					    ...),
-			      void *cbarg)
+			      void (*dyingcb)(struct short_channel_id scid,
+					      u32 blockheight,
+					      u64 offset,
+					      void *cb_arg),
+			      void *cb_arg)
 {
 	map = tal(ctx, struct gossmap);
 	map->generation = 0;
@@ -1331,15 +1389,15 @@ struct gossmap *gossmap_load_(const tal_t *ctx,
 		map->logcb = logcb;
 	else
 		map->logcb = log_stderr;
-	map->cbarg = cbarg;
+	map->cbarg = cb_arg;
 	tal_add_destructor(map, destroy_map);
 
-	if (!load_gossip_store(map, expected_len != 0))
+	if (!load_gossip_store(map, dyingcb, cb_arg, expected_len != 0))
 		return tal_free(map);
 	if (expected_len != 0
 	    && (map->map_size != map->map_end
 		|| map->map_size != expected_len)) {
-		logcb(cbarg, LOG_BROKEN,
+		logcb(cb_arg, LOG_BROKEN,
 		      "gossip_store only processed %"PRIu64
 		      " bytes of %"PRIu64" (expected %"PRIu64")",
 		      map->map_end, map->map_size, expected_len);
diff --git a/common/gossmap.h b/common/gossmap.h
index 1b60a1fd..0c1a0425 100644
--- a/common/gossmap.h
+++ b/common/gossmap.h
@@ -46,17 +46,21 @@ struct gossmap_chan {
 					   enum log_level,		\
 					   const char *fmt,		\
 					   ...),			\
-		      (cbarg))
+		      NULL, (cbarg))
 
 /* If we're the author of the gossmap, it should have no redundant records, corruption, etc.
  * So this fails if that's not the case. */
-#define gossmap_load_initial(ctx, filename, expected_len, logcb, cbarg)	\
+#define gossmap_load_initial(ctx, filename, expected_len, logcb, dyingcb, cb_arg) \
 	gossmap_load_((ctx), (filename), (expected_len),			\
-		      typesafe_cb_postargs(void, void *, (logcb), (cbarg), \
+		      typesafe_cb_postargs(void, void *, (logcb), (cb_arg), \
 					   enum log_level,		\
 					   const char *fmt,		\
 					   ...),			\
-		      (cbarg))
+		      typesafe_cb_preargs(void, void *, (dyingcb), (cb_arg), \
+					  struct short_channel_id,	\
+					  u32,				\
+					  u64),				\
+		      (cb_arg))
 
 struct gossmap *gossmap_load_(const tal_t *ctx,
 			      const char *filename,
@@ -65,6 +69,10 @@ struct gossmap *gossmap_load_(const tal_t *ctx,
 					    enum log_level level,
 					    const char *fmt,
 					    ...),
+			      void (*dyingcb)(struct short_channel_id scid,
+					      u32 blockheight,
+					      u64 offset,
+					      void *cb_arg),
 			      void *cb_arg);
 
 /* Disable mmap.  Noop if already disabled. */
@@ -305,4 +313,5 @@ u64 gossmap_lengths(const struct gossmap *map, u64 *total);
 
 /* Debugging: connectd wants to enumerate fds */
 int gossmap_fd(const struct gossmap *map);
+
 #endif /* LIGHTNING_COMMON_GOSSMAP_H */
diff --git a/common/test/run-gossmap_canned.c b/common/test/run-gossmap_canned.c
index fd5af5e0..8ae7210d 100644
--- a/common/test/run-gossmap_canned.c
+++ b/common/test/run-gossmap_canned.c
@@ -19,6 +19,9 @@ bigsize_t fromwire_bigsize(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
 bool fromwire_channel_id(const u8 **cursor UNNEEDED, size_t *max UNNEEDED,
 			 struct channel_id *channel_id UNNEEDED)
 { fprintf(stderr, "fromwire_channel_id called!\n"); abort(); }
+/* Generated stub for fromwire_gossip_store_chan_dying */
+bool fromwire_gossip_store_chan_dying(const void *p UNNEEDED, struct short_channel_id *scid UNNEEDED, u32 *blockheight UNNEEDED)
+{ fprintf(stderr, "fromwire_gossip_store_chan_dying called!\n"); abort(); }
 /* Generated stub for sciddir_or_pubkey_from_node_id */
 bool sciddir_or_pubkey_from_node_id(struct sciddir_or_pubkey *sciddpk UNNEEDED,
 				    const struct node_id *node_id UNNEEDED)
diff --git a/common/test/run-gossmap_local.c b/common/test/run-gossmap_local.c
index b425710a..0575bcae 100644
--- a/common/test/run-gossmap_local.c
+++ b/common/test/run-gossmap_local.c
@@ -19,6 +19,9 @@ bigsize_t fromwire_bigsize(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
 bool fromwire_channel_id(const u8 **cursor UNNEEDED, size_t *max UNNEEDED,
 			 struct channel_id *channel_id UNNEEDED)
 { fprintf(stderr, "fromwire_channel_id called!\n"); abort(); }
+/* Generated stub for fromwire_gossip_store_chan_dying */
+bool fromwire_gossip_store_chan_dying(const void *p UNNEEDED, struct short_channel_id *scid UNNEEDED, u32 *blockheight UNNEEDED)
+{ fprintf(stderr, "fromwire_gossip_store_chan_dying called!\n"); abort(); }
 /* Generated stub for sciddir_or_pubkey_from_node_id */
 bool sciddir_or_pubkey_from_node_id(struct sciddir_or_pubkey *sciddpk UNNEEDED,
 				    const struct node_id *node_id UNNEEDED)
diff --git a/connectd/test/run-crc32_of_update.c b/connectd/test/run-crc32_of_update.c
index 85521395..62c3c5fe 100644
--- a/connectd/test/run-crc32_of_update.c
+++ b/connectd/test/run-crc32_of_update.c
@@ -10,12 +10,16 @@ int unused_main(int argc, char *argv[]);
 #include <common/memleak.h>
 #include <common/onionreply.h>
 #include <common/setup.h>
+#include <common/gossip_store_wiregen.h>
 #include <stdio.h>
 
 /* AUTOGENERATED MOCKS START */
 /* Generated stub for fromwire_connectd_dev_set_max_scids_encode_size */
 bool fromwire_connectd_dev_set_max_scids_encode_size(const void *p UNNEEDED, u32 *max UNNEEDED)
 { fprintf(stderr, "fromwire_connectd_dev_set_max_scids_encode_size called!\n"); abort(); }
+/* Generated stub for fromwire_gossip_store_chan_dying */
+bool fromwire_gossip_store_chan_dying(const void *p UNNEEDED, struct short_channel_id *scid UNNEEDED, u32 *blockheight UNNEEDED)
+{ fprintf(stderr, "fromwire_gossip_store_chan_dying called!\n"); abort(); }
 /* Generated stub for get_gossmap */
 struct gossmap *get_gossmap(struct daemon *daemon UNNEEDED)
 { fprintf(stderr, "get_gossmap called!\n"); abort(); }
diff --git a/gossipd/gossmap_manage.c b/gossipd/gossmap_manage.c
index 4ae675d8..cc4c6264 100644
--- a/gossipd/gossmap_manage.c
+++ b/gossipd/gossmap_manage.c
@@ -464,7 +464,9 @@ static bool setup_gossmap(struct gossmap_manage *gm,
 	/* This actually loads it into memory, with strict checks. */
 	gm->raw_gossmap = gossmap_load_initial(gm, GOSSIP_STORE_FILENAME,
 					       expected_len,
-					       gossmap_logcb, daemon);
+					       gossmap_logcb,
+					       NULL,
+					       daemon);
 	if (!gm->raw_gossmap) {
 		gm->gs = tal_free(gm->gs);
 		return false;
diff --git a/gossipd/test/run-next_block_range.c b/gossipd/test/run-next_block_range.c
index 60b9530a..f4dae400 100644
--- a/gossipd/test/run-next_block_range.c
+++ b/gossipd/test/run-next_block_range.c
@@ -9,6 +9,7 @@
 #include <common/sciddir_or_pubkey.h>
 #include <common/setup.h>
 #include <common/wireaddr.h>
+#include <common/gossip_store_wiregen.h>
 #include <stdio.h>
 
 /* AUTOGENERATED MOCKS START */
@@ -19,6 +20,9 @@ struct peer *find_peer(struct daemon *daemon UNNEEDED, const struct node_id *id
 struct peer *first_random_peer(struct daemon *daemon UNNEEDED,
 			       struct peer_node_id_map_iter *it UNNEEDED)
 { fprintf(stderr, "first_random_peer called!\n"); abort(); }
+/* Generated stub for fromwire_gossip_store_chan_dying */
+bool fromwire_gossip_store_chan_dying(const void *p UNNEEDED, struct short_channel_id *scid UNNEEDED, u32 *blockheight UNNEEDED)
+{ fprintf(stderr, "fromwire_gossip_store_chan_dying called!\n"); abort(); }
 /* Generated stub for gossmap_manage_get_gossmap */
 struct gossmap *gossmap_manage_get_gossmap(struct gossmap_manage *gm UNNEEDED)
 { fprintf(stderr, "gossmap_manage_get_gossmap called!\n"); abort(); }