invoice: Consider aliases too when selecting routehints

lightningd/channel.c

@@ -664,6 +664,18 @@ struct channel *find_channel_by_scid(const struct peer *peer,
 	return NULL;
 }
 
+struct channel *find_channel_by_alias(const struct peer *peer,
+				      const struct short_channel_id *alias,
+				      enum side side)
+{
+	struct channel *c;
+	list_for_each(&peer->channels, c, list) {
+		if (c->alias[side] && short_channel_id_eq(c->alias[side], alias))
+			return c;
+	}
+	return NULL;
+}
+
 void channel_set_last_tx(struct channel *channel,
 			 struct bitcoin_tx *tx,
 			 const struct bitcoin_signature *sig,

lightningd/channel.h

@@ -417,6 +417,11 @@ struct channel *find_channel_by_id(const struct peer *peer,
 struct channel *find_channel_by_scid(const struct peer *peer,
 				     const struct short_channel_id *scid);
 
+/* Find a channel by its alias, either local or remote. */
+struct channel *find_channel_by_alias(const struct peer *peer,
+				      const struct short_channel_id *alias,
+				      enum side side);
+
 void channel_set_last_tx(struct channel *channel,
 			 struct bitcoin_tx *tx,
 			 const struct bitcoin_signature *sig,

lightningd/routehint.c

@@ -106,6 +106,15 @@ routehint_candidates(const tal_t *ctx,
 
 		/* Check channel is in CHANNELD_NORMAL */
 		candidate.c = find_channel_by_scid(peer, &r->short_channel_id);
+
+		/* Try seeing if we should be using a remote alias
+		 * instead. The `listpeers` result may have returned
+		 * the REMOTE alias, because it is the only scid we
+		 * have, and it is mandatory once the channel is in
+		 * CHANNELD_NORMAL. */
+		if (!candidate.c)
+			candidate.c = find_channel_by_alias(peer, &r->short_channel_id, REMOTE);
+
 		if (!candidate.c) {
 			log_debug(ld->log, "%s: channel not found in peer %s",
 				  type_to_string(tmpctx,

lightningd/test/run-invoice-select-inchan.c

@@ -187,6 +187,11 @@ bool feature_negotiated(const struct feature_set *our_features UNNEEDED,
 /* Generated stub for featurebits_or */
 u8 *featurebits_or(const tal_t *ctx UNNEEDED, const u8 *f1 TAKES UNNEEDED, const u8 *f2 TAKES UNNEEDED)
 { fprintf(stderr, "featurebits_or called!\n"); abort(); }
+/* Generated stub for find_channel_by_alias */
+struct channel *find_channel_by_alias(const struct peer *peer UNNEEDED,
+				      const struct short_channel_id *alias UNNEEDED,
+				      enum side side UNNEEDED)
+{ fprintf(stderr, "find_channel_by_alias called!\n"); abort(); }
 /* Generated stub for find_channel_by_id */
 struct channel *find_channel_by_id(const struct peer *peer UNNEEDED,
 				   const struct channel_id *cid UNNEEDED)

plugins/libplugin-pay.c

@@ -3228,9 +3228,17 @@ static struct command_result *direct_pay_listpeers(struct command *cmd,
 			if (!streq(chan->state, "CHANNELD_NORMAL"))
 			    continue;
 
+			/* Must have either a local alias for zeroconf
+			 * channels or a final scid. */
+			assert(chan->alias[LOCAL] || chan->scid);
 			d->chan = tal(d, struct short_channel_id_dir);
-			d->chan->scid = *chan->scid;
-			d->chan->dir = *chan->direction;
+			if (chan->scid) {
+				d->chan->scid = *chan->scid;
+				d->chan->dir = *chan->direction;
+			} else {
+				d->chan->scid = *chan->alias[LOCAL];
+				d->chan->dir = 0; /* Don't care. */
+			}
 		}
 	}
 cont:

plugins/libplugin.c

@@ -1581,10 +1581,10 @@ static struct listpeers_channel *json_to_listpeers_channel(const tal_t *ctx,
 			*scidtok =
 			    json_get_member(buffer, tok, "short_channel_id"),
 			*dirtok = json_get_member(buffer, tok, "direction"),
-			*tmsattok =
-			    json_get_member(buffer, tok, "total_msat"),
+			*tmsattok = json_get_member(buffer, tok, "total_msat"),
 			*smsattok =
-			    json_get_member(buffer, tok, "spendable_msat");
+			    json_get_member(buffer, tok, "spendable_msat"),
+			*aliastok = json_get_member(buffer, tok, "alias");
 
 	if (privtok == NULL || privtok->type != JSMN_PRIMITIVE ||
 	    statetok == NULL || statetok->type != JSMN_STRING ||
@@ -1611,6 +1611,25 @@ static struct listpeers_channel *json_to_listpeers_channel(const tal_t *ctx,
 		chan->scid = NULL;
 		chan->direction = NULL;
 	}
+	if (aliastok != NULL) {
+		const jsmntok_t *loctok =
+				    json_get_member(buffer, aliastok, "local"),
+				*remtok =
+				    json_get_member(buffer, aliastok, "remote");
+		if (loctok) {
+			chan->alias[LOCAL] = tal(chan, struct short_channel_id);
+			json_to_short_channel_id(buffer, loctok,
+						 chan->alias[LOCAL]);
+		} else
+			chan->alias[LOCAL] = NULL;
+
+		if (remtok) {
+			chan->alias[REMOTE] = tal(chan, struct short_channel_id);
+			json_to_short_channel_id(buffer, loctok,
+						 chan->alias[REMOTE]);
+		} else
+			chan->alias[REMOTE] = NULL;
+	}
 
 	json_to_msat(buffer, tmsattok, &chan->total_msat);
 	json_to_msat(buffer, smsattok, &chan->spendable_msat);

plugins/libplugin.h

@@ -10,6 +10,7 @@
 #include <ccan/timer/timer.h>
 #include <common/errcode.h>
 #include <common/features.h>
+#include <common/htlc.h>
 #include <common/json.h>
 #include <common/json_command.h>
 #include <common/json_helpers.h>
@@ -318,6 +319,7 @@ struct listpeers_channel {
 	bool private;
 	struct bitcoin_txid funding_txid;
 	const char *state;
+	struct short_channel_id *alias[NUM_SIDES];
 	struct short_channel_id *scid;
 	int *direction;
 	struct amount_msat total_msat;