askrene: change getroutes amount and delay values

In the previous implementation getroutes would provide for every i-th
hop the value of the amount and delay which correspond to the (i-1)-th
HTLC. This commit changes that, instead the i-th hop contains the value
of the amount and delay of the i-th HTLC.

Changelog-Changed: askrene: getroutes outputs contains for each hop the correct amount and delay values.

Signed-off-by: Lagrang3 <lagrang3@protonmail.com>

Author: Lagrang3

contrib/msggen/msggen/schema.json

@@ -16190,7 +16190,7 @@
                       "delay": {
                         "type": "u32",
                         "description": [
-                          "The total CLTV expected by the node at the start of this hop."
+                          "The total CLTV on this hop's HTLC."
                         ]
                       }
                     }
@@ -16241,14 +16241,14 @@
                   {
                     "short_channel_id_dir": "109x1x1/1",
                     "next_node_id": "nodeid020202020202020202020202020202020202020202020202020202020202",
-                    "amount_msat": 1250026,
-                    "delay": 12
+                    "amount_msat": 1250013,
+                    "delay": 6
                   },
                   {
                     "short_channel_id_dir": "123x1x1/0",
                     "next_node_id": "nodeid030303030303030303030303030303030303030303030303030303030303",
-                    "amount_msat": 1250013,
-                    "delay": 6
+                    "amount_msat": 1250000,
+                    "delay": 0
                   }
                 ]
               }

doc/schemas/lightning-getroutes.json

@@ -155,7 +155,7 @@
                   "delay": {
                     "type": "u32",
                     "description": [
-                      "The total CLTV expected by the node at the start of this hop."
+                      "The total CLTV on this hop's HTLC."
                     ]
                   }
                 }
@@ -206,14 +206,14 @@
               {
                 "short_channel_id_dir": "109x1x1/1",
                 "next_node_id": "nodeid020202020202020202020202020202020202020202020202020202020202",
-                "amount_msat": 1250026,
-                "delay": 12
+                "amount_msat": 1250013,
+                "delay": 6
               },
               {
                 "short_channel_id_dir": "123x1x1/0",
                 "next_node_id": "nodeid030303030303030303030303030303030303030303030303030303030303",
-                "amount_msat": 1250013,
-                "delay": 6
+                "amount_msat": 1250000,
+                "delay": 0
               }
             ]
           }

plugins/askrene/askrene.c

@@ -526,6 +526,8 @@ static const char *get_routes(const tal_t *ctx,
 			struct gossmap_node *far_end;
 			const struct half_chan *h = flow_edge(flows[i], j);
 
+			rh->amount = msat;
+			rh->delay = delay;
 			if (!amount_msat_add_fee(&msat, h->base_fee, h->proportional_fee))
 				plugin_err(rq->plugin, "Adding fee to amount");
 			delay += h->delay;
@@ -534,8 +536,6 @@ static const char *get_routes(const tal_t *ctx,
 			rh->direction = flows[i]->dirs[j];
 			far_end = gossmap_nth_node(rq->gossmap, flows[i]->path[j], !flows[i]->dirs[j]);
 			gossmap_node_get_id(rq->gossmap, far_end, &rh->node_id);
-			rh->amount = msat;
-			rh->delay = delay;
 		}
 		(*amounts)[i] = flows[i]->delivers;
 		rq_log(tmpctx, rq, LOG_INFORM, "Flow %zu/%zu: %s",

plugins/xpay/xpay.c

@@ -127,12 +127,8 @@ struct hop {
 	struct pubkey next_node;
 	/* Via this channel */
 	struct short_channel_id_dir scidd;
-	/* This is amount the node needs (including fees) */
-	struct amount_msat amount_in;
 	/* ... to send this amount */
 	struct amount_msat amount_out;
-	/* This is the delay, including delay across node */
-	u32 cltv_value_in;
 	/* This is the delay, out from node. */
 	u32 cltv_value_out;
 };
@@ -347,14 +343,14 @@ static struct amount_msat initial_sent(const struct attempt *attempt)
 {
 	if (tal_count(attempt->hops) == 0)
 		return attempt->delivers;
-	return attempt->hops[0].amount_in;
+	return attempt->hops[0].amount_out;
 }
 
 static u32 initial_cltv_delta(const struct attempt *attempt)
 {
 	if (tal_count(attempt->hops) == 0)
 		return attempt->payment->final_cltv;
-	return attempt->hops[0].cltv_value_in;
+	return attempt->hops[0].cltv_value_out;
 }
 
 /* The current attempt is the first to succeed: we assume all the ones
@@ -776,7 +772,7 @@ static struct amount_msat total_fees_being_sent(const struct payment *payment)
 		if (tal_count(attempt->hops) == 0)
 			continue;
 		if (!amount_msat_sub(&fee,
-				     attempt->hops[0].amount_in,
+				     attempt->hops[0].amount_out,
 				     attempt->delivers))
 			abort();
 		if (!amount_msat_accumulate(&sum, fee))
@@ -1053,16 +1049,12 @@ static struct command_result *getroutes_done(struct command *aux_cmd,
 					",delay:%}",
 					JSON_SCAN(json_to_short_channel_id_dir,
 						  &hop->scidd),
-					JSON_SCAN(json_to_msat, &hop->amount_in),
+					JSON_SCAN(json_to_msat, &hop->amount_out),
 					JSON_SCAN(json_to_pubkey, &hop->next_node),
-					JSON_SCAN(json_to_u32, &hop->cltv_value_in));
+					JSON_SCAN(json_to_u32, &hop->cltv_value_out));
 			if (err)
 				plugin_err(aux_cmd->plugin, "Malformed routes: %s",
 					   err);
-			if (j > 0) {
-				hops[j-1].amount_out = hop->amount_in;
-				hops[j-1].cltv_value_out = hop->cltv_value_in;
-			}
 		}
 		hops[j-1].amount_out = delivers;
 		hops[j-1].cltv_value_out = payment->final_cltv;