gossmap_manage: new file for managing the gossip store.

This is a fair amount of code, but much is taken from
the old routing.c, with the difference that this uses
common/gossmap instead of our own structures.

The interfaces are fairly clear:

1. gossmap_manage_new - allocator
2. gossmap_manage_channel_announcement
   - handle new channel announcement msg
   - if too early, keeps it in early map
   - queues it, asks lightingd about UTXO.
3. gossmap_manage_handle_get_txout_reply
   - handle response from lightningd for above.
4. gossmap_manage_channel_update
   - handle channel_update message
   - may have to wait on pending channel_announcement
5. gossmap_manage_node_announcement
   - handle node_announcement msg
   - may have to wait on pending channel_announcement
6. gossmap_manage_new_block
   - see if early announces can now be processed.
7. gossmap_manage_channel_spent
   - lightningd tells us UTXO is spent
   - may prepare channel for closing in 12 blocks.
8. gossmap_manage_channel_dying
   - gossip_store load tells us channel was spent earlier.
   - like gossmap_manage_channel_spent, but maybe < 12.
9. gossmap_manage_get_gossmap
   - gossmap accessor: seeker and queries will need this.
10. gossmap_manage_new_peer
   - a new peer has connected, give them all our gossip.

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

gossipd/gossip_store.c

@@ -10,6 +10,7 @@
 #include <fcntl.h>
 #include <gossipd/gossip_store.h>
 #include <gossipd/gossip_store_wiregen.h>
+#include <gossipd/routing.h>
 #include <sys/stat.h>
 #include <sys/uio.h>
 #include <unistd.h>

gossipd/gossip_store.h

@@ -7,13 +7,14 @@
 #include <ccan/list/list.h>
 #include <ccan/short_types/short_types.h>
 #include <ccan/tal/tal.h>
-#include <gossipd/routing.h>
 
 /**
  * gossip_store -- On-disk storage related information
  */
 
 struct gossip_store;
+struct broadcastable;
+struct daemon;
 struct routing_state;
 
 struct gossip_store *gossip_store_new(struct daemon *daemon);

gossipd/gossmap_manage.h

@@ -0,0 +1,112 @@
+#ifndef LIGHTNING_GOSSIPD_GOSSMAP_MANAGE_H
+#define LIGHTNING_GOSSIPD_GOSSMAP_MANAGE_H
+#include "config.h"
+
+struct daemon;
+struct gossmap_manage;
+
+struct gossmap_manage *gossmap_manage_new(const tal_t *ctx,
+					  struct daemon *daemon);
+
+/**
+ * gossmap_manage_channel_announcement: process an incoming channel_announcement
+ * @ctx: tal context for return string
+ * @gm: the gossmap_manage context
+ * @announce: the channel_announcement message
+ * @source_peer: peer who sent this (NULL if it's from lightningd)
+ *
+ * Returns an error string if it wasn't redundant or included.
+ */
+const char *gossmap_manage_channel_announcement(const tal_t *ctx,
+						struct gossmap_manage *gm,
+						const u8 *announce TAKES,
+						const struct node_id *source_peer TAKES);
+
+
+/**
+ * gossmap_manage_handle_get_txout_reply: process a txout reply from lightningd
+ * @gm: the gossmap_manage context
+ * @msg: the message
+ *
+ * Since handle_channel_announcement asks lightning for utxos,
+ * it gets called back here.
+ */
+void gossmap_manage_handle_get_txout_reply(struct gossmap_manage *gm, const u8 *msg);
+
+/**
+ * gossmap_manage_channel_update: process an incoming channel_update
+ * @ctx: tal context for return string
+ * @gm: the gossmap_manage context
+ * @update: the channel_update message
+ * @source_peer: optional peer who sent this
+ *
+ * Returns an error string if it wasn't redundant or included.
+ */
+const char *gossmap_manage_channel_update(const tal_t *ctx,
+					  struct gossmap_manage *gm,
+					  const u8 *update TAKES,
+					  const struct node_id *source_peer TAKES);
+
+/**
+ * gossmap_manage_node_announcement: process an incoming node_announcement
+ * @ctx: tal context for return string allocation
+ * @gm: the gossmap_manage context
+ * @node_announcement: the node_announcement message
+ * @source_peer: optional peer who sent this
+ *
+ * Returns an error string if it wasn't redundant or included.
+ */
+const char *gossmap_manage_node_announcement(const tal_t *ctx,
+					     struct gossmap_manage *gm,
+					     const u8 *node_announcement TAKES,
+					     const struct node_id *source_peer TAKES);
+
+/**
+ * gossmap_manage_new_block: handle block height update.
+ * @gm: the gossmap_manage context
+ * @new_blockheight: the new blockheight
+ */
+void gossmap_manage_new_block(struct gossmap_manage *gm, u32 new_blockheight);
+
+/**
+ * gossmap_manage_channel_spent: handle an UTXO being spent
+ * @gm: the gossmap_manage context
+ * @blockheight: the blockheight it was spent at
+ * @scid: the short_channel_id
+ *
+ * lightningd tells us all the possible UTXOs spent every block: most
+ * don't match channels.
+ */
+void gossmap_manage_channel_spent(struct gossmap_manage *gm,
+				  u32 blockheight,
+				  struct short_channel_id scid);
+
+/**
+ * gossmap_manage_channel_dying: dying channel loaded from store.
+ * @gm: the gossmap_manage context
+ * @offset: the offset of the dying marker in the store.
+ * @deadline: the blockheight it is to expire
+ * @scid: the short_channel_id
+ *
+ * Returns false if this channel does not exist (already dead!).
+ */
+bool gossmap_manage_channel_dying(struct gossmap_manage *gm,
+				  u64 gossmap_offset,
+				  u32 deadline,
+				  struct short_channel_id scid);
+
+/**
+ * gossmap_manage_get_gossmap: get the (refreshed!) gossmap
+ * @gm: the gossmap_manage context
+ */
+struct gossmap *gossmap_manage_get_gossmap(struct gossmap_manage *gm);
+
+/**
+ * gossmap_manage_new_peer: send all our own gossip to this peer.
+ * @gm: the gossmap_manage context
+ * @peer: the node_id of the peer.
+ */
+void gossmap_manage_new_peer(struct gossmap_manage *gm,
+			     const struct node_id *peer);
+
+#endif /* LIGHTNING_GOSSIPD_GOSSMAP_MANAGE_H */