common: generic routine to turn listpeerchannels into gossmap local updates.

This is more thorough than the minimal one required for getroute(), including the feerates
and cltv deltas.

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

common/Makefile

@@ -39,6 +39,7 @@ COMMON_SRC_NOGEN :=				\
 	common/fp16.c				\
 	common/gossip_store.c			\
 	common/gossmap.c			\
+	common/gossmods_listpeerchannels.c	\
 	common/hash_u5.c			\
 	common/hmac.c				\
 	common/hsm_encryption.c			\

common/gossmods_listpeerchannels.c

@@ -0,0 +1,158 @@
+#include "config.h"
+#include <ccan/err/err.h>
+#include <common/gossmap.h>
+#include <common/gossmods_listpeerchannels.h>
+#include <common/node_id.h>
+#include <plugins/libplugin.h>
+
+void gossmod_add_localchan(struct gossmap_localmods *mods,
+			   const struct node_id *self,
+			   const struct node_id *peer,
+			   const struct short_channel_id_dir *scidd,
+			   struct amount_msat min,
+			   struct amount_msat max,
+			   struct amount_msat fee_base,
+			   u32 fee_proportional,
+			   u32 cltv_delta,
+			   bool enabled,
+			   const char *buf UNUSED,
+			   const jsmntok_t *chantok UNUSED,
+			   void *cbarg UNUSED)
+{
+	/* FIXME: features? */
+	gossmap_local_addchan(mods, self, peer, &scidd->scid, NULL);
+
+	gossmap_local_updatechan(mods, &scidd->scid, min, max,
+				 fee_base.millisatoshis, /* Raw: gossmap */
+				 fee_proportional,
+				 cltv_delta,
+				 enabled,
+				 scidd->dir);
+}
+
+struct gossmap_localmods *
+gossmods_from_listpeerchannels_(const tal_t *ctx,
+				const struct node_id *self,
+				const char *buf,
+				const jsmntok_t *toks,
+				void (*cb)(struct gossmap_localmods *mods,
+					   const struct node_id *self,
+					   const struct node_id *peer,
+					   const struct short_channel_id_dir *scidd,
+					   struct amount_msat min,
+					   struct amount_msat max,
+					   struct amount_msat fee_base,
+					   u32 fee_proportional,
+					   u32 cltv_delta,
+					   bool enabled,
+					   const char *buf,
+					   const jsmntok_t *chantok,
+					   void *cbarg),
+				void *cbarg)
+{
+	struct gossmap_localmods *mods = gossmap_localmods_new(ctx);
+	const jsmntok_t *channels, *channel;
+	size_t i;
+
+	channels = json_get_member(buf, toks, "channels");
+	json_for_each_arr(i, channel, channels) {
+		struct short_channel_id_dir scidd;
+		struct short_channel_id alias;
+		bool enabled;
+		struct node_id dst;
+		struct amount_msat spendable, receivable, fee_base[NUM_SIDES], htlc_min[NUM_SIDES], htlc_max[NUM_SIDES];
+		u32 fee_proportional[NUM_SIDES], cltv_delta[NUM_SIDES];
+		const char *state, *err;
+
+		/* scid/direction and alias may not exist. */
+		scidd.scid.u64 = 0;
+		alias.u64 = 0;
+
+		/* We do this to note if we have no remote update. */
+		fee_proportional[REMOTE] = -1U;
+
+		err = json_scan(tmpctx, buf, channel,
+				"{short_channel_id?:%,"
+				"direction?:%,"
+				"spendable_msat?:%,"
+				"receivable_msat?:%,"
+				"peer_connected:%,"
+				"state:%,"
+				"peer_id:%,"
+				"updates?:{"
+				 "local"
+				 ":{fee_base_msat:%,"
+				 "fee_proportional_millionths:%,"
+				 "htlc_minimum_msat:%,"
+				 "htlc_maximum_msat:%,"
+				 "cltv_expiry_delta:%},"
+				 "remote?"
+				 ":{fee_base_msat:%,"
+				 "fee_proportional_millionths:%,"
+				 "htlc_minimum_msat:%,"
+				 "htlc_maximum_msat:%,"
+				 "cltv_expiry_delta:%}},"
+				"alias?:{local:%}}",
+				JSON_SCAN(json_to_short_channel_id, &scidd.scid),
+				JSON_SCAN(json_to_int, &scidd.dir),
+				JSON_SCAN(json_to_msat, &spendable),
+				JSON_SCAN(json_to_msat, &receivable),
+				JSON_SCAN(json_to_bool, &enabled),
+				JSON_SCAN_TAL(tmpctx, json_strdup, &state),
+				JSON_SCAN(json_to_node_id, &dst),
+				JSON_SCAN(json_to_msat, &fee_base[LOCAL]),
+				JSON_SCAN(json_to_u32, &fee_proportional[LOCAL]),
+				JSON_SCAN(json_to_msat, &htlc_min[LOCAL]),
+				JSON_SCAN(json_to_msat, &htlc_max[LOCAL]),
+				JSON_SCAN(json_to_u32, &cltv_delta[LOCAL]),
+				JSON_SCAN(json_to_msat, &fee_base[REMOTE]),
+				JSON_SCAN(json_to_u32, &fee_proportional[REMOTE]),
+				JSON_SCAN(json_to_msat, &htlc_min[REMOTE]),
+				JSON_SCAN(json_to_msat, &htlc_max[REMOTE]),
+				JSON_SCAN(json_to_u32, &cltv_delta[REMOTE]),
+				JSON_SCAN(json_to_short_channel_id, &alias));
+		if (err) {
+			errx(1, "Bad listpeerchannels.channels %zu: %s",
+			     i, err);
+		}
+
+		/* Use alias if no scid.  Note: if alias is set, direction is present */
+		if (scidd.scid.u64 == 0 && alias.u64 != 0)
+			scidd.scid = alias;
+
+		/* Unusable if no scid (yet) */
+		if (scidd.scid.u64 == 0)
+			continue;
+
+		/* Disable if in bad state (it's already false if not connected) */
+		if (!streq(state, "CHANNELD_NORMAL")
+		      && !streq(state, "CHANNELD_AWAITING_SPLICE"))
+			enabled = false;
+
+		/* Cut htlc max to spendable. */
+		if (amount_msat_less(spendable, htlc_max[LOCAL]))
+			htlc_max[LOCAL] = spendable;
+
+		/* We add both directions */
+		cb(mods, self, &dst, &scidd, htlc_min[LOCAL], htlc_max[LOCAL],
+		   fee_base[LOCAL], fee_proportional[LOCAL], cltv_delta[LOCAL],
+		   enabled, buf, channel, cbarg);
+
+		/* If we didn't have a remote update, it's not usable yet */
+		if (fee_proportional[REMOTE] == -1U)
+			continue;
+
+		scidd.dir = !scidd.dir;
+
+		/* Cut htlc max to receivable. */
+		if (amount_msat_less(receivable, htlc_max[REMOTE]))
+			htlc_max[REMOTE] = receivable;
+
+		cb(mods, self, &dst, &scidd, htlc_min[REMOTE], htlc_max[REMOTE],
+		   fee_base[REMOTE], fee_proportional[REMOTE], cltv_delta[REMOTE],
+		   enabled, buf, channel, cbarg);
+	}
+
+	return mods;
+}
+

common/gossmods_listpeerchannels.h

@@ -0,0 +1,74 @@
+#ifndef LIGHTNING_COMMON_GOSSMODS_LISTPEERCHANNELS_H
+#define LIGHTNING_COMMON_GOSSMODS_LISTPEERCHANNELS_H
+#include "config.h"
+#include <bitcoin/short_channel_id.h>
+#include <ccan/typesafe_cb/typesafe_cb.h>
+#include <common/amount.h>
+#include <common/json_parse_simple.h>
+
+struct node_id;
+
+/**
+ * gossmods_from_listpeerchannels: create gossmap_localmods from `listpeerchannels`
+ * @ctx: context to allocate return from
+ * @buf: the JSON buffer from listpeerchannels
+ * @toks: the JSON tokens
+ * @cb: optional per-channel callback.
+ * @cbarg: arg for @cb.
+ *
+ * This constructs a set of modifications you can apply to your gossmap to include
+ * local (esp. private) channels.  You can also have an optional per-channel callback
+ * for special effects.
+ */
+struct gossmap_localmods *gossmods_from_listpeerchannels_(const tal_t *ctx,
+							  const struct node_id *self,
+							  const char *buf,
+							  const jsmntok_t *toks,
+							  void (*cb)(struct gossmap_localmods *mods,
+								     const struct node_id *self_,
+								     const struct node_id *peer,
+								     const struct short_channel_id_dir *scidd,
+								     struct amount_msat min,
+								     struct amount_msat max,
+								     struct amount_msat fee_base,
+								     u32 fee_proportional,
+								     u32 cltv_delta,
+								     bool enabled,
+								     const char *buf_,
+								     const jsmntok_t *chantok,
+								     void *cbarg_),
+							  void *cbarg);
+
+#define gossmods_from_listpeerchannels(ctx, self, buf, toks, cb, cbarg) \
+	gossmods_from_listpeerchannels_((ctx), (self), (buf), (toks), \
+					typesafe_cb_preargs(void, void *, (cb), (cbarg), \
+							    struct gossmap_localmods *, \
+							    const struct node_id *, \
+							    const struct node_id *, \
+							    const struct short_channel_id_dir *, \
+							    struct amount_msat,	\
+							    struct amount_msat,	\
+							    struct amount_msat,	\
+							    u32,	\
+							    u32,	\
+							    bool,	\
+							    const char *, \
+							    const jsmntok_t *), \
+					(cbarg))
+
+/* Callback which simply adds to gossmap. */
+void gossmod_add_localchan(struct gossmap_localmods *mods,
+			   const struct node_id *self,
+			   const struct node_id *peer,
+			   const struct short_channel_id_dir *scidd,
+			   struct amount_msat min,
+			   struct amount_msat max,
+			   struct amount_msat fee_base,
+			   u32 fee_proportional,
+			   u32 cltv_delta,
+			   bool enabled,
+			   const char *buf UNUSED,
+			   const jsmntok_t *chantok UNUSED,
+			   void *cbarg UNUSED);
+
+#endif /* LIGHTNING_COMMON_GOSSMODS_LISTPEERCHANNELS_H */

plugins/topology.c

@@ -6,6 +6,7 @@
 #include <ccan/tal/str/str.h>
 #include <common/dijkstra.h>
 #include <common/gossmap.h>
+#include <common/gossmods_listpeerchannels.h>
 #include <common/json_param.h>
 #include <common/json_stream.h>
 #include <common/memleak.h>
@@ -148,86 +149,6 @@ static struct command_result *try_route(struct command *cmd,
 	return command_finished(cmd, js);
 }
 
-static struct gossmap_localmods *
-gossmods_from_listpeerchannels(const tal_t *ctx,
-			       struct plugin *plugin,
-			       struct gossmap *gossmap,
-			       const char *buf,
-			       const jsmntok_t *toks)
-{
-	struct gossmap_localmods *mods = gossmap_localmods_new(ctx);
-	const jsmntok_t *channels, *channel;
-	size_t i;
-
-	channels = json_get_member(buf, toks, "channels");
-	json_for_each_arr(i, channel, channels) {
-		struct short_channel_id scid;
-		int dir;
-		bool connected;
-		struct node_id dst;
-		struct amount_msat capacity;
-		const char *state, *err;
-
-		/* scid/direction may not exist. */
-		scid.u64 = 0;
-		capacity = AMOUNT_MSAT(0);
-		err = json_scan(tmpctx, buf, channel,
-				"{short_channel_id?:%,"
-				"direction?:%,"
-				"spendable_msat?:%,"
-				"peer_connected:%,"
-				"state:%,"
-				"peer_id:%}",
-				JSON_SCAN(json_to_short_channel_id, &scid),
-				JSON_SCAN(json_to_int, &dir),
-				JSON_SCAN(json_to_msat, &capacity),
-				JSON_SCAN(json_to_bool, &connected),
-				JSON_SCAN_TAL(tmpctx, json_strdup, &state),
-				JSON_SCAN(json_to_node_id, &dst));
-		if (err) {
-			plugin_err(plugin,
-				   "Bad listpeerchannels.channels %zu: %s",
-				   i, err);
-		}
-
-		/* Unusable if no scid (yet) */
-		if (scid.u64 == 0)
-			continue;
-
-		/* Disable if in bad state, or disconnected */
-		if (!streq(state, "CHANNELD_NORMAL")
-		    && !streq(state, "CHANNELD_AWAITING_SPLICE")) {
-			goto disable;
-		}
-
-		if (!connected) {
-			goto disable;
-		}
-
-		/* FIXME: features? */
-		gossmap_local_addchan(mods, &local_id, &dst, &scid, NULL);
-		gossmap_local_updatechan(mods, &scid,
-					 AMOUNT_MSAT(0), capacity,
-					 /* We don't charge ourselves fees */
-					 0, 0, 0,
-					 true,
-					 dir);
-		continue;
-
-	disable:
-		/* Only apply fake "disabled" if channel exists */
-		if (gossmap_find_chan(gossmap, &scid)) {
-			gossmap_local_updatechan(mods, &scid,
-						 AMOUNT_MSAT(0), AMOUNT_MSAT(0),
-						 0, 0, 0,
-						 false,
-						 dir);
-		}
-	}
-
-	return mods;
-}
-
 static struct command_result *
 listpeerchannels_getroute_done(struct command *cmd,
 			       const char *buf,
@@ -239,11 +160,12 @@ listpeerchannels_getroute_done(struct command *cmd,
 	struct command_result *res;
 
 	/* Get local knowledge */
-	gossmap = get_gossmap();
+	mods = gossmods_from_listpeerchannels(tmpctx, &local_id,
-	mods = gossmods_from_listpeerchannels(tmpctx, cmd->plugin,
+					      buf, result,
-					      gossmap, buf, result);
+					      gossmod_add_localchan, NULL);
 
 	/* Overlay local knowledge for dijkstra */
+	gossmap = get_gossmap();
 	gossmap_apply_localmods(gossmap, mods);
 	res = try_route(cmd, gossmap, info);
 	gossmap_remove_localmods(gossmap, mods);