getroute: allow caller to specify maximum hops.

This is required for routeboost.

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

gossipd/gossip_wire.csv

@@ -35,6 +35,7 @@ gossip_getroute_request,,fuzz,double
 gossip_getroute_request,,num_excluded,u16
 gossip_getroute_request,,excluded,num_excluded*struct short_channel_id
 gossip_getroute_request,,excluded_dir,num_excluded*bool
+gossip_getroute_request,,max_hops,u32
 
 gossip_getroute_reply,3106
 gossip_getroute_reply,,num_hops,u16

gossipd/gossipd.c

@@ -1867,6 +1867,7 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 	u64 msatoshi;
 	u32 final_cltv;
 	u16 riskfactor;
+	u32 max_hops;
 	u8 *out;
 	struct route_hop *hops;
 	double fuzz;
@@ -1883,7 +1884,8 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 					      &source, &destination,
 					      &msatoshi, &riskfactor,
 					      &final_cltv, &fuzz,
-					      &excluded, &excluded_dir))
+					      &excluded, &excluded_dir,
+					      &max_hops))
 		master_badmsg(WIRE_GOSSIP_GETROUTE_REQUEST, msg);
 
 	status_trace("Trying to find a route from %s to %s for %"PRIu64" msatoshi",
@@ -1893,7 +1895,7 @@ static struct io_plan *getroute_req(struct io_conn *conn, struct daemon *daemon,
 	/* routing.c does all the hard work; can return NULL. */
 	hops = get_route(tmpctx, daemon->rstate, &source, &destination,
 			 msatoshi, riskfactor, final_cltv,
-			 fuzz, siphash_seed(), excluded, excluded_dir);
+			 fuzz, siphash_seed(), excluded, excluded_dir, max_hops);
 
 	out = towire_gossip_getroute_reply(NULL, hops);
 	daemon_conn_send(daemon->master, take(out));

gossipd/routing.c

@@ -377,7 +377,8 @@ static bool hc_can_carry(const struct half_chan *hc, u64 requiredcap)
 static void bfg_one_edge(struct node *node,
 			 struct chan *chan, int idx,
 			 double riskfactor,
-			 double fuzz, const struct siphash_seed *base_seed)
+			 double fuzz, const struct siphash_seed *base_seed,
+			 size_t max_hops)
 {
 	size_t h;
 	double fee_scale = 1.0;
@@ -394,7 +395,7 @@ static void bfg_one_edge(struct node *node,
 		fee_scale = 1.0 + (2.0 * fuzz * h / UINT64_MAX) - fuzz;
 	}
 
-	for (h = 0; h < ROUTING_MAX_HOPS; h++) {
+	for (h = 0; h < max_hops; h++) {
 		struct node *src;
 		/* FIXME: Bias against smaller channels. */
 		u64 fee;
@@ -450,6 +451,7 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 	   const struct pubkey *from, const struct pubkey *to, u64 msatoshi,
 	   double riskfactor,
 	   double fuzz, const struct siphash_seed *base_seed,
+	   size_t max_hops,
 	   u64 *fee)
 {
 	struct chan **route;
@@ -486,6 +488,11 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 		return NULL;
 	}
 
+	if (max_hops > ROUTING_MAX_HOPS) {
+		status_info("find_route: max_hops huge amount %zu", max_hops);
+		return NULL;
+	}
+
 	/* Reset all the information. */
 	clear_bfg(rstate->nodes);
 
@@ -494,7 +501,7 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 	src->bfg[0].total = msatoshi;
 	src->bfg[0].risk = 0;
 
-	for (runs = 0; runs < ROUTING_MAX_HOPS; runs++) {
+	for (runs = 0; runs < max_hops; runs++) {
 		SUPERVERBOSE("Run %i", runs);
 		/* Run through every edge. */
 		for (n = node_map_first(rstate->nodes, &it);
@@ -518,14 +525,15 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 					continue;
 				}
 				bfg_one_edge(n, chan, idx,
-					     riskfactor, fuzz, base_seed);
+					     riskfactor, fuzz, base_seed,
+					     max_hops);
 				SUPERVERBOSE("...done");
 			}
 		}
 	}
 
 	best = 0;
-	for (i = 1; i <= ROUTING_MAX_HOPS; i++) {
+	for (i = 1; i <= max_hops; i++) {
 		if (dst->bfg[i].total < dst->bfg[best].total)
 			best = i;
 	}
@@ -1498,7 +1506,8 @@ struct route_hop *get_route(const tal_t *ctx, struct routing_state *rstate,
 			    u32 final_cltv,
 			    double fuzz, const struct siphash_seed *base_seed,
 			    const struct short_channel_id *excluded,
-			    const bool *excluded_dir)
+			    const bool *excluded_dir,
+			    size_t max_hops)
 {
 	struct chan **route;
 	u64 total_amount;
@@ -1523,7 +1532,7 @@ struct route_hop *get_route(const tal_t *ctx, struct routing_state *rstate,
 
 	route = find_route(ctx, rstate, source, destination, msatoshi,
 			   riskfactor / BLOCKS_PER_YEAR / 10000,
-			   fuzz, base_seed, &fee);
+			   fuzz, base_seed, max_hops, &fee);
 
 	/* Now restore the capacity. */
 	for (size_t i = 0; i < tal_count(excluded); i++) {

gossipd/routing.h

@@ -269,7 +269,8 @@ struct route_hop *get_route(const tal_t *ctx, struct routing_state *rstate,
 			    double fuzz,
 			    const struct siphash_seed *base_seed,
 			    const struct short_channel_id *excluded,
-			    const bool *excluded_dir);
+			    const bool *excluded_dir,
+			    size_t max_hops);
 /* Disable channel(s) based on the given routing failure. */
 void routing_failure(struct routing_state *rstate,
 		     const struct pubkey *erring_node,

gossipd/test/run-bench-find_route.c

@@ -261,6 +261,7 @@ int main(int argc, char *argv[])
 				   pseudorand(100000),
 				   riskfactor,
 				   0.75, &base_seed,
+				   ROUTING_MAX_HOPS,
 				   &fee);
 		num_success += (route != NULL);
 		tal_free(route);

gossipd/test/run-find_route-specific.c

@@ -222,7 +222,8 @@ int main(void)
 	nc->message_flags = 0;
 	nc->last_timestamp = 1504064344;
 
-	route = find_route(tmpctx, rstate, &a, &c, 100000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 100000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 2);
 	assert(channel_is_between(route[0], &a, &b));
@@ -230,17 +231,20 @@ int main(void)
 
 
 	/* We should not be able to find a route that exceeds our own capacity */
-	route = find_route(tmpctx, rstate, &a, &c, 1000001, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 1000001, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(!route);
 
 	/* Now test with a query that exceeds the channel capacity after adding
 	 * some fees */
-	route = find_route(tmpctx, rstate, &a, &c, 999999, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 999999, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(!route);
 
 	/* This should fail to return a route because it is smaller than these
 	 * htlc_minimum_msat on the last channel. */
-	route = find_route(tmpctx, rstate, &a, &c, 1, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 1, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(!route);
 
 	/* {'active': True, 'short_id': '6990:2:1/0', 'fee_per_kw': 10, 'delay': 5, 'message_flags': 1, 'htlc_maximum_msat': 500000, 'htlc_minimum_msat': 100, 'channel_flags': 0, 'destination': '02cca6c5c966fcf61d121e3a70e03a1cd9eeeea024b26ea666ce974d43b242e636', 'source': '03c173897878996287a8100469f954dd820fcd8941daed91c327f168f3329be0bf', 'last_update': 1504064344}, */
@@ -255,12 +259,14 @@ int main(void)
 	nc->htlc_maximum_msat = 500000; /* half capacity */
 
 	/* This should route correctly at the max_msat level */
-	route = find_route(tmpctx, rstate, &a, &d, 500000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &d, 500000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 
 	/* This should fail to return a route because it's larger than the
 	 * htlc_maximum_msat on the last channel. */
-	route = find_route(tmpctx, rstate, &a, &d, 500001, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &d, 500001, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(!route);
 
 	tal_free(tmpctx);

gossipd/test/run-find_route.c

@@ -222,7 +222,8 @@ int main(void)
 	/* A<->B */
 	add_connection(rstate, &a, &b, 1, 1, 1);
 
-	route = find_route(tmpctx, rstate, &a, &b, 1000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &b, 1000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 1);
 	assert(fee == 0);
@@ -237,7 +238,8 @@ int main(void)
 	status_trace("C = %s", type_to_string(tmpctx, struct pubkey, &c));
 	add_connection(rstate, &b, &c, 1, 1, 1);
 
-	route = find_route(tmpctx, rstate, &a, &c, 1000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 1000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 2);
 	assert(fee == 1);
@@ -252,7 +254,8 @@ int main(void)
 	add_connection(rstate, &d, &c, 0, 2, 1);
 
 	/* Will go via D for small amounts. */
-	route = find_route(tmpctx, rstate, &a, &c, 1000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 1000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 2);
 	assert(channel_is_between(route[0], &a, &d));
@@ -260,7 +263,8 @@ int main(void)
 	assert(fee == 0);
 
 	/* Will go via B for large amounts. */
-	route = find_route(tmpctx, rstate, &a, &c, 3000000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 3000000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 2);
 	assert(channel_is_between(route[0], &a, &b));
@@ -269,7 +273,8 @@ int main(void)
 
 	/* Make B->C inactive, force it back via D */
 	get_connection(rstate, &b, &c)->channel_flags |= ROUTING_FLAGS_DISABLED;
-	route = find_route(tmpctx, rstate, &a, &c, 3000000, riskfactor, 0.0, NULL, &fee);
+	route = find_route(tmpctx, rstate, &a, &c, 3000000, riskfactor, 0.0, NULL,
+			   ROUTING_MAX_HOPS, &fee);
 	assert(route);
 	assert(tal_count(route) == 2);
 	assert(channel_is_between(route[0], &a, &d));

lightningd/gossip_control.c

@@ -327,6 +327,7 @@ static struct command_result *json_getroute(struct command *cmd,
 	double *riskfactor;
 	struct short_channel_id *excluded;
 	bool *excluded_dir;
+	u32 *max_hops;
 
 	/* Higher fuzz means that some high-fee paths can be discounted
 	 * for an even larger value, increasing the scope for route
@@ -343,6 +344,8 @@ static struct command_result *json_getroute(struct command *cmd,
 		   p_opt_def("fromid", param_pubkey, &source, ld->id),
 		   p_opt_def("fuzzpercent", param_percent, &fuzz, 5.0),
 		   p_opt("exclude", param_array, &excludetok),
+		   p_opt_def("maxhops", param_number, &max_hops,
+			     ROUTING_MAX_HOPS),
 		   NULL))
 		return command_param_failed();
 
@@ -378,7 +381,8 @@ static struct command_result *json_getroute(struct command *cmd,
 	u8 *req = towire_gossip_getroute_request(cmd, source, destination,
 						 *msatoshi, *riskfactor * 1000,
 						 *cltv, fuzz,
-						 excluded, excluded_dir);
+						 excluded, excluded_dir,
+						 *max_hops);
 	subd_req(ld->gossip, ld->gossip, req, -1, 0, json_getroute_reply, cmd);
 	return command_still_pending(cmd);
 }

lightningd/payalgo.c

@@ -557,7 +557,8 @@ static struct command_result *json_pay_try(struct pay *pay)
 					     pay->msatoshi + overpayment,
 					     pay->riskfactor,
 					     pay->min_final_cltv_expiry,
-					     &pay->fuzz, NULL, NULL);
+					     &pay->fuzz, NULL, NULL,
+					     ROUTING_MAX_HOPS);
 	subd_req(pay->try_parent, cmd->ld->gossip, req, -1, 0, json_pay_getroute_reply, pay);
 
 	return NULL;