dijkstra: add chan pointer argument to path scoring.

For fuzz, we will need some fixed per-channel data (so we always fuzz
a channel the same way).

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

common/dijkstra.c

@@ -143,7 +143,8 @@ dijkstra_(const tal_t *ctx,
 			     void *arg),
 	  u64 (*path_score)(u32 distance,
 			    struct amount_msat cost,
-			    struct amount_msat risk),
+			    struct amount_msat risk,
+			    const struct gossmap_chan *c),
 	  void *arg)
 {
 	struct dijkstra *dij;
@@ -250,7 +251,7 @@ dijkstra_(const tal_t *ctx,
 			risk = risk_price(cost, riskfactor,
 					  cur_d->total_delay
 					  + c->half[!which_half].delay);
-			score = path_score(cur_d->distance + 1, cost, risk);
+			score = path_score(cur_d->distance + 1, cost, risk, c);
 			if (score >= d->score)
 				continue;
 

common/dijkstra.h

@@ -23,7 +23,8 @@ dijkstra_(const tal_t *ctx,
 			     void *arg),
 	  u64 (*path_score)(u32 distance,
 			    struct amount_msat cost,
-			    struct amount_msat risk),
+			    struct amount_msat risk,
+			    const struct gossmap_chan *c),
 	  void *arg);
 
 #define dijkstra(ctx, map, start, amount, riskfactor, channel_ok,	\

common/route.c

@@ -51,7 +51,8 @@ static u32 costs_to_score(struct amount_msat cost,
 /* Prioritize distance over costs */
 u64 route_score_shorter(u32 distance,
 			struct amount_msat cost,
-			struct amount_msat risk)
+			struct amount_msat risk,
+			const struct gossmap_chan *c UNUSED)
 {
 	return costs_to_score(cost, risk) + ((u64)distance << 32);
 }
@@ -59,7 +60,8 @@ u64 route_score_shorter(u32 distance,
 /* Prioritize costs over distance */
 u64 route_score_cheaper(u32 distance,
 			struct amount_msat cost,
-			struct amount_msat risk)
+			struct amount_msat risk,
+			const struct gossmap_chan *c UNUSED)
 {
 	return ((u64)costs_to_score(cost, risk) << 32) + distance;
 }

common/route.h

@@ -56,12 +56,14 @@ bool route_can_carry_even_disabled(const struct gossmap *map,
 /* Shortest path, with lower amount tiebreak */
 u64 route_score_shorter(u32 distance,
 			struct amount_msat cost,
-			struct amount_msat risk);
+			struct amount_msat risk,
+			const struct gossmap_chan *c UNUSED);
 
 /* Cheapest path, with shorter path tiebreak */
 u64 route_score_cheaper(u32 distance,
 			struct amount_msat cost,
-			struct amount_msat risk);
+			struct amount_msat risk,
+			const struct gossmap_chan *c UNUSED);
 
 /* Extract route tal_arr from completed dijkstra: NULL if none. */
 struct route_hop *route_from_dijkstra(const tal_t *ctx,