renepay: enable routing through blinded paths

Enable routing through blinded paths using fake channels in local
gossmods.

Changelog-None

Signed-off-by: Lagrang3 <[email protected]>

Author: Lagrang3

plugins/renepay/main.c

@@ -343,6 +343,7 @@ static struct command_result *json_pay(struct command *cmd, const char *buf,
 
 			pinfo->blinded_paths = NULL;
 			pinfo->blinded_payinfos = NULL;
+			payment->routing_destination = &pinfo->destination;
 		} else {
 			pinfo->payment_secret = NULL;
 			pinfo->routehints = NULL;
@@ -368,6 +369,18 @@ static struct command_result *json_pay(struct command *cmd, const char *buf,
 					max_final_cltv = final_cltv;
 			}
 			pinfo->final_cltv = max_final_cltv;
+			
+			/* When dealing with BOLT12 blinded paths we compute the
+			 * routing targeting a fake node to enable
+			 * multi-destination minimum-cost-flow. Every blinded
+			 * path entry node will be linked to this fake node
+			 * using fake channels as well. */
+			payment->routing_destination =
+			    tal(payment, struct node_id);
+			if (!node_id_from_hexstr(
+				"02""0000000000000000000000000000000000000000000000000000000000000001",
+				66, payment->routing_destination))
+				abort();
 		}
 
 		if (!payment_set_constraints(

plugins/renepay/mods.c

@@ -13,6 +13,7 @@
 #include <plugins/renepay/routebuilder.h>
 #include <plugins/renepay/routetracker.h>
 #include <unistd.h>
+#include <wire/bolt12_wiregen.h>
 
 #define INVALID_ID UINT32_MAX
 
@@ -515,7 +516,9 @@ REGISTER_PAYMENT_MODIFIER(refreshgossmap, refreshgossmap_cb);
 static void add_hintchan(struct payment *payment, const struct node_id *src,
 			 const struct node_id *dst, u16 cltv_expiry_delta,
 			 const struct short_channel_id scid, u32 fee_base_msat,
-			 u32 fee_proportional_millionths)
+			 u32 fee_proportional_millionths,
+			 const struct amount_msat *chan_htlc_min,
+			 const struct amount_msat *chan_htlc_max)
 {
 	assert(payment);
 	assert(payment->local_gossmods);
@@ -528,6 +531,12 @@ static void add_hintchan(struct payment *payment, const struct node_id *src,
 		struct short_channel_id_dir scidd;
 		/* We assume any HTLC is allowed */
 		struct amount_msat htlc_min = AMOUNT_MSAT(0), htlc_max = MAX_CAPACITY;
+
+		if (chan_htlc_min)
+			htlc_min = *chan_htlc_min;
+		if (chan_htlc_max)
+			htlc_max = *chan_htlc_max;
+
 		struct amount_msat fee_base = amount_msat(fee_base_msat);
 		bool enabled = true;
 		scidd.scid = scid;
@@ -604,7 +613,8 @@ static struct command_result *routehints_done(struct command *cmd UNUSED,
 			add_hintchan(payment, &r[j].pubkey, end,
 				     r[j].cltv_expiry_delta,
 				     r[j].short_channel_id, r[j].fee_base_msat,
-				     r[j].fee_proportional_millionths);
+				     r[j].fee_proportional_millionths,
+				     NULL, NULL);
 			end = &r[j].pubkey;
 		}
 	}
@@ -625,6 +635,8 @@ static struct command_result *routehints_done(struct command *cmd UNUSED,
 
 static struct command_result *routehints_cb(struct payment *payment)
 {
+	if (payment->payment_info.routehints == NULL)
+		return payment_continue(payment);
 	struct command *cmd = payment_command(payment);
 	assert(cmd);
 	struct out_req *req = jsonrpc_request_start(
@@ -636,6 +648,44 @@ static struct command_result *routehints_cb(struct payment *payment)
 
 REGISTER_PAYMENT_MODIFIER(routehints, routehints_cb);
 
+
+/*****************************************************************************
+ * blindedhints
+ *
+ * Similar to routehints but for bolt12 invoices: create fake channel that
+ * connect the blinded path entry point to the destination node.
+ */
+
+static struct command_result *blindedhints_cb(struct payment *payment)
+{
+	if (payment->payment_info.blinded_paths == NULL)
+		return payment_continue(payment);
+
+	struct payment_info *pinfo = &payment->payment_info;
+	struct short_channel_id scid;
+	struct node_id src;
+
+	for (size_t i = 0; i < tal_count(pinfo->blinded_paths); i++) {
+		const struct blinded_payinfo *payinfo =
+		    pinfo->blinded_payinfos[i];
+		const struct blinded_path *path = pinfo->blinded_paths[i];
+
+		scid.u64 = i; // a fake scid
+		node_id_from_pubkey(&src, &path->first_node_id.pubkey);
+
+		add_hintchan(payment, &src, payment->routing_destination,
+			     payinfo->cltv_expiry_delta, scid,
+			     payinfo->fee_base_msat,
+			     payinfo->fee_proportional_millionths,
+			     &payinfo->htlc_minimum_msat,
+			     &payinfo->htlc_maximum_msat);
+	}
+	return payment_continue(payment);
+}
+
+REGISTER_PAYMENT_MODIFIER(blindedhints, blindedhints_cb);
+
+
 /*****************************************************************************
  * compute_routes
  *
@@ -694,23 +744,30 @@ static struct command_result *compute_routes_cb(struct payment *payment)
 	 * better to pass computed_routes as a reference? */
 	routetracker->computed_routes = tal_free(routetracker->computed_routes);
 
+	/* Send get_routes a note that it should discard the last hop because we
+	 * are actually solving a multiple destinations problem. */
+	bool blinded_destination =
+	    payment->payment_info.blinded_paths != NULL;
+
 	// TODO: add an algorithm selector here
 	/* We let this return an unlikely path, as it's better to try  once than
 	 * simply refuse.  Plus, models are not truth! */
 	routetracker->computed_routes = get_routes(
 					    routetracker,
 					    &payment->payment_info,
 					    &pay_plugin->my_id,
-					    &payment->payment_info.destination,
+					    payment->routing_destination,
 					    pay_plugin->gossmap,
 					    pay_plugin->uncertainty,
 					    payment->disabledmap,
 					    remaining,
 					    feebudget,
 					    &payment->next_partid,
 					    payment->groupid,
+					    blinded_destination,
 					    &errcode,
 					    &err_msg);
+
 	/* Otherwise the error message remains a child of the routetracker. */
 	err_msg = tal_steal(tmpctx, err_msg);
 
@@ -1230,20 +1287,21 @@ void *payment_virtual_program[] = {
     /*6*/ OP_CALL, &getmychannels_pay_mod,
     /*8*/ OP_CALL, &refreshgossmap_pay_mod,
     /*10*/ OP_CALL, &routehints_pay_mod,
-    /*12*/OP_CALL, &channelfilter_pay_mod,
+    /*12*/ OP_CALL, &blindedhints_pay_mod,
+    /*14*/OP_CALL, &channelfilter_pay_mod,
     // TODO shadow_additions
     /* do */
-	    /*14*/ OP_CALL, &pendingsendpays_pay_mod,
-	    /*16*/ OP_CALL, &checktimeout_pay_mod,
-	    /*18*/ OP_CALL, &refreshgossmap_pay_mod,
-	    /*20*/ OP_CALL, &compute_routes_pay_mod,
-	    /*22*/ OP_CALL, &send_routes_pay_mod,
+	    /*16*/ OP_CALL, &pendingsendpays_pay_mod,
+	    /*18*/ OP_CALL, &checktimeout_pay_mod,
+	    /*20*/ OP_CALL, &refreshgossmap_pay_mod,
+	    /*22*/ OP_CALL, &compute_routes_pay_mod,
+	    /*24*/ OP_CALL, &send_routes_pay_mod,
 	    /*do*/
-		    /*24*/ OP_CALL, &sleep_pay_mod,
-		    /*26*/ OP_CALL, &collect_results_pay_mod,
+		    /*26*/ OP_CALL, &sleep_pay_mod,
+		    /*28*/ OP_CALL, &collect_results_pay_mod,
 	    /*while*/
-	    /*28*/ OP_IF, &nothaveresults_pay_cond, (void *)24,
+	    /*30*/ OP_IF, &nothaveresults_pay_cond, (void *)26,
     /* while */
-    /*31*/ OP_IF, &retry_pay_cond, (void *)14,
-    /*34*/ OP_CALL, &end_pay_mod, /* safety net, default failure if reached */
-    /*36*/ NULL};
+    /*33*/ OP_IF, &retry_pay_cond, (void *)16,
+    /*36*/ OP_CALL, &end_pay_mod, /* safety net, default failure if reached */
+    /*38*/ NULL};

plugins/renepay/payment.h

@@ -56,6 +56,10 @@ struct payment {
 	/* Localmods to apply to gossip_map for our own use. */
 	struct gossmap_localmods *local_gossmods;
 
+	/* Routes will be computed to reach this node, could be a fake node that
+	 * we use to handle multiple blinded paths. */
+	struct node_id *routing_destination;
+
 	struct disabledmap *disabledmap;
 
 	/* Flag to indicate wether we have collected enough results to make a

plugins/renepay/route.c

@@ -19,6 +19,7 @@ struct route *new_route(const tal_t *ctx, u32 groupid,
 
 	route->amount = amount;
 	route->amount_sent = amount_sent;
+	route->path_num = -1;
 	return route;
 }
 
@@ -32,7 +33,8 @@ struct route *new_route(const tal_t *ctx, u32 groupid,
 struct route *flow_to_route(const tal_t *ctx,
 			    u32 groupid, u32 partid, struct sha256 payment_hash,
 			    u32 final_cltv, struct gossmap *gossmap,
-			    struct flow *flow)
+			    struct flow *flow,
+			    bool blinded_destination)
 {
 	struct route *route =
 	    new_route(ctx, groupid, partid, payment_hash,
@@ -67,6 +69,12 @@ struct route *flow_to_route(const tal_t *ctx,
 	route->success_prob = flow->success_prob;
 	route->amount = route->hops[pathlen - 1].amount;
 	route->amount_sent = route->hops[0].amount;
+
+	if (blinded_destination) {
+		route->path_num = route->hops[pathlen - 1].scid.u64;
+		tal_arr_remove(&route->hops, pathlen - 1);
+	}
+
 	return route;
 
 function_fail:
@@ -85,7 +93,8 @@ struct route **flows_to_routes(const tal_t *ctx,
 	for (size_t i = 0; i < N; i++) {
 		routes[i] =
 		    flow_to_route(routes, groupid, partid++,
-				  payment_hash, final_cltv, gossmap, flows[i]);
+				  payment_hash, final_cltv, gossmap, flows[i],
+				  false);
 		if (!routes[i])
 			goto function_fail;
 	}

plugins/renepay/route.h

@@ -68,6 +68,9 @@ struct route {
 
 	/* result of waitsenday */
 	struct payment_result *result;
+
+	/* blinded path index if any */
+	int path_num;
 };
 
 static inline struct routekey routekey(const struct sha256 *hash, u64 groupid,
@@ -117,7 +120,8 @@ struct route *new_route(const tal_t *ctx, u32 groupid,
 struct route *flow_to_route(const tal_t *ctx,
 			    u32 groupid, u32 partid, struct sha256 payment_hash,
 			    u32 final_cltv, struct gossmap *gossmap,
-			    struct flow *flow);
+			    struct flow *flow,
+			    bool blinded_destination);
 
 struct route **flows_to_routes(const tal_t *ctx,
 			       u32 groupid, u32 partid,

plugins/renepay/routebuilder.c

@@ -140,6 +140,7 @@ struct route **get_routes(const tal_t *ctx,
 
 			  u64 *next_partid,
 			  u64 groupid,
+			  bool blinded_destination,
 
 			  enum jsonrpc_errcode *ecode,
 			  const char **fail)
@@ -297,7 +298,8 @@ struct route **get_routes(const tal_t *ctx,
 			struct route *r = flow_to_route(
 			    this_ctx, groupid, *next_partid,
 			    payment_info->payment_hash,
-			    payment_info->final_cltv, gossmap, flows[i]);
+			    payment_info->final_cltv, gossmap, flows[i],
+			    blinded_destination);
 
 			if (!r) {
 				tal_report_error(

plugins/renepay/routebuilder.h

@@ -23,6 +23,7 @@ struct route **get_routes(const tal_t *ctx,
 
 			  u64 *next_partid,
 			  u64 groupid,
+			  bool blinded_destination,
 
 			  enum jsonrpc_errcode *ecode,
 			  const char **fail);

plugins/renepay/test/run-bottleneck.c

@@ -263,6 +263,7 @@ int main(int argc, char *argv[])
 		/* feebudget */maxfee,
 		&next_partid,
 		groupid,
+		false,
 		&errcode,
 		&err_msg);
 

plugins/renepay/test/run-testflow.c

@@ -691,7 +691,7 @@ static void test_flow_to_route(void)
 	F->dirs[0]=0;
 	deliver = AMOUNT_MSAT(250000000);
 	F->amount = deliver;
-	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F);
+	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F, false);
 	assert(route);
 
 	assert(amount_msat_eq(route->hops[0].amount, deliver));
@@ -707,7 +707,7 @@ static void test_flow_to_route(void)
 	F->dirs[1]=0;
 	deliver = AMOUNT_MSAT(250000000);
 	F->amount=deliver;
-	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F);
+	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F, false);
 	assert(route);
 
 	assert(amount_msat_eq(route->hops[0].amount, amount_msat(250050016)));
@@ -725,7 +725,7 @@ static void test_flow_to_route(void)
 	F->dirs[2]=0;
 	deliver = AMOUNT_MSAT(250000000);
 	F->amount=deliver;
-	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F);
+	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F, false);
 	assert(route);
 
 	assert(amount_msat_eq(route->hops[0].amount, amount_msat(250087534)));
@@ -745,7 +745,7 @@ static void test_flow_to_route(void)
 	F->dirs[3]=0;
 	deliver = AMOUNT_MSAT(250000000);
 	F->amount=deliver;
-	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F);
+	route = flow_to_route(this_ctx, 1, 1, payment_hash, 0, gossmap, F, false);
 	assert(route);
 
 	assert(amount_msat_eq(route->hops[0].amount, amount_msat(250112544)));