plugins/libplugin-pay: hack in blinded path support.

We simply take the first one, and route to the start of that.  Then we
append the blinded path to the onion construction.

Signed-off-by: Rusty Russell <[email protected]>

plugins/Makefile

@@ -172,7 +172,7 @@ ALL_PROGRAMS += $(C_PLUGINS)
 # Make all plugins depend on all plugin headers, for simplicity.
 $(PLUGIN_ALL_OBJS): $(PLUGIN_ALL_HEADER)
 
-plugins/pay: $(PLUGIN_PAY_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) common/gossmap.o common/fp16.o common/route.o common/dijkstra.o common/bolt12.o common/bolt12_merkle.o wire/bolt12$(EXP)_wiregen.o bitcoin/block.o
+plugins/pay: $(PLUGIN_PAY_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) common/gossmap.o common/fp16.o common/route.o common/dijkstra.o common/bolt12.o common/bolt12_merkle.o wire/bolt12$(EXP)_wiregen.o bitcoin/block.o common/blindedpay.o common/blindedpath.o common/hmac.o common/blinding.o common/onion_encode.o
 
 plugins/autoclean: $(PLUGIN_AUTOCLEAN_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS)
 
@@ -188,7 +188,7 @@ plugins/txprepare: $(PLUGIN_TXPREPARE_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_O
 
 plugins/bcli: $(PLUGIN_BCLI_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS)
 
-plugins/keysend: wire/tlvstream.o wire/onion$(EXP)_wiregen.o $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) common/gossmap.o common/fp16.o common/route.o common/dijkstra.o
+plugins/keysend: wire/tlvstream.o wire/onion$(EXP)_wiregen.o $(PLUGIN_KEYSEND_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_PAY_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS) common/gossmap.o common/fp16.o common/route.o common/dijkstra.o common/blindedpay.o common/blindedpath.o common/hmac.o common/blinding.o common/onion_encode.o
 $(PLUGIN_KEYSEND_OBJS): $(PLUGIN_PAY_LIB_HEADER)
 
 plugins/spenderp: bitcoin/block.o bitcoin/preimage.o bitcoin/psbt.o common/psbt_open.o wire/peer${EXP}_wiregen.o $(PLUGIN_SPENDER_OBJS) $(PLUGIN_LIB_OBJS) $(PLUGIN_COMMON_OBJS) $(JSMN_OBJS)

plugins/keysend.c

@@ -174,6 +174,8 @@ static struct command_result *json_keysend(struct command *cmd, const char *buf,
 	p->destination = tal_steal(p, destination);
 	p->payment_secret = NULL;
 	p->payment_metadata = NULL;
+	p->blindedpath = NULL;
+	p->blindedpay = NULL;
 	p->amount = *msat;
 	p->routes = tal_steal(p, hints);
 	// 22 is the Rust-Lightning default and the highest minimum we know of.

plugins/libplugin-pay.c

@@ -1,6 +1,7 @@
 #include "config.h"
 #include <ccan/array_size/array_size.h>
 #include <ccan/tal/str/str.h>
+#include <common/blindedpay.h>
 #include <common/dijkstra.h>
 #include <common/gossmap.h>
 #include <common/json_stream.h>
@@ -1662,6 +1663,33 @@ static void payment_add_hop_onion_payload(struct payment *p,
 	}
 }
 
+static void payment_add_blindedpath(const tal_t *ctx,
+				    struct createonion_hop *hops,
+				    const struct blinded_path *bpath,
+				    struct amount_msat final_amt,
+				    u32 final_cltv)
+{
+	/* It's a bit of a weird API for us, so we convert it back to
+	 * the struct tlv_tlv_payload */
+	u8 **tlvs = blinded_onion_hops(tmpctx, final_amt, final_cltv, bpath);
+
+	for (size_t i = 0; i < tal_count(tlvs); i++) {
+		const u8 *cursor = tlvs[i];
+		size_t max = tal_bytelen(tlvs[i]);
+		/* First one has to use real node_id */
+		if (i == 0)
+			node_id_from_pubkey(&hops[i].pubkey,
+					    &bpath->first_node_id);
+		else
+			node_id_from_pubkey(&hops[i].pubkey,
+					    &bpath->path[i]->blinded_node_id);
+
+		/* Length is prepended, discard that first! */
+		fromwire_bigsize(&cursor, &max);
+		hops[i].tlv_payload = fromwire_tlv_tlv_payload(ctx, &cursor, &max);
+	}
+}
+
 static void payment_compute_onion_payloads(struct payment *p)
 {
 	struct createonion_request *cr;
@@ -1690,7 +1718,9 @@ static void payment_compute_onion_payloads(struct payment *p)
 	cr->assocdata = tal_arr(cr, u8, 0);
 	towire_sha256(&cr->assocdata, p->payment_hash);
 	cr->session_key = NULL;
-	cr->hops = tal_arr(cr, struct createonion_hop, tal_count(p->route));
+	cr->hops = tal_arr(cr, struct createonion_hop,
+			   tal_count(p->route)
+			   + (root->blindedpath ? tal_count(root->blindedpath->path) - 1: 0));
 
 	/* Non-final hops */
 	for (size_t i = 0; i < hopcount - 1; i++) {
@@ -1704,14 +1734,27 @@ static void payment_compute_onion_payloads(struct payment *p)
 					      &p->route[i].scid));
 	}
 
-	/* Final hop */
-	payment_add_hop_onion_payload(
-	    p, &cr->hops[hopcount - 1], &p->route[hopcount - 1],
-	    &p->route[hopcount - 1], true,
-	    root->payment_secret, root->payment_metadata);
-	tal_append_fmt(&routetxt, "%s",
-		       type_to_string(tmpctx, struct short_channel_id,
-				      &p->route[hopcount - 1].scid));
+	/* If we're headed to a blinded path, connect that now. */
+	if (root->blindedpath) {
+		payment_add_blindedpath(cr->hops, cr->hops + hopcount - 1,
+					root->blindedpath,
+					root->blindedfinalamount,
+					root->blindedfinalcltv);
+		tal_append_fmt(&routetxt, "%s -> blinded path (%zu hops)",
+			       type_to_string(tmpctx, struct short_channel_id,
+					      &p->route[hopcount-1].scid),
+			       tal_count(root->blindedpath->path));
+	} else {
+		/* Final hop */
+		payment_add_hop_onion_payload(
+			p, &cr->hops[hopcount - 1], &p->route[hopcount - 1],
+			&p->route[hopcount - 1], true,
+			root->payment_secret,
+			root->payment_metadata);
+		tal_append_fmt(&routetxt, "%s",
+			       type_to_string(tmpctx, struct short_channel_id,
+					      &p->route[hopcount - 1].scid));
+	}
 
 	paymod_log(p, LOG_DBG,
 		   "Created outgoing onion for route: %s", routetxt);

plugins/libplugin-pay.h

@@ -188,6 +188,12 @@ struct payment {
 	/* Payment metadata, from the invoice if any. */
 	u8 *payment_metadata;
 
+	/* Blinded path (for bolt12) */
+	struct blinded_path *blindedpath;
+	struct blinded_payinfo *blindedpay;
+	struct amount_msat blindedfinalamount;
+	u32 blindedfinalcltv;
+
 	u64 groupid;
 	u32 partid;
 	u32 next_partid;

plugins/pay.c

@@ -1024,6 +1024,9 @@ static struct command_result *json_pay(struct command *cmd,
 	p = payment_new(cmd, cmd, NULL /* No parent */, paymod_mods);
 	p->invstring = tal_steal(p, b11str);
 	p->description = tal_steal(p, description);
+	/* Overridded by bolt12 if present */
+	p->blindedpath = NULL;
+	p->blindedpay = NULL;
 
 	if (!bolt12_has_prefix(b11str)) {
 		b11 =
@@ -1085,7 +1088,9 @@ static struct command_result *json_pay(struct command *cmd,
 			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "experimental-offers disabled");
 
-		p->features = tal_steal(p, b12->features);
+		/* FIXME: We disable MPP for now */
+		/* p->features = tal_steal(p, b12->features); */
+		p->features = NULL;
 
 		if (!b12->node_id)
 			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
@@ -1109,8 +1114,33 @@ static struct command_result *json_pay(struct command *cmd,
 			return command_fail(
 			    cmd, JSONRPC2_INVALID_PARAMS,
 			    "recurring invoice requires a label");
-		/* FIXME payment_secret should be signature! */
-		{
+
+		/* BOLT-offers #12:
+		 * - MUST reject the invoice if `blindedpay` is not present.
+		 */
+		/* FIXME: We allow this for now. */
+
+		if (tal_count(b12->paths) != 0) {
+			/* BOLT-offers #12: - MUST reject the invoice if
+			 * `blindedpay` does not contain exactly one
+			 * `blinded_payinfo` per `blinded_path`.
+			 */
+			if (tal_count(b12->paths) != tal_count(b12->blindedpay)) {
+				return command_fail(
+					cmd, JSONRPC2_INVALID_PARAMS,
+					"Wrong blinding info: %zu paths, %zu payinfo",
+					tal_count(b12->paths),
+					tal_count(b12->blindedpay));
+			}
+
+			/* FIXME: do MPP across these!  We choose first one. */
+			p->blindedpath = tal_steal(p, b12->paths[0]);
+			p->blindedpay = tal_steal(p, b12->blindedpay[0]);
+
+			/* Set destination to introduction point */
+			node_id_from_pubkey(p->destination, &p->blindedpath->first_node_id);
+		} else {
+			/* FIXME payment_secret should be signature! */
 			struct sha256 merkle;
 
 			p->payment_secret = tal(p, struct secret);
@@ -1121,7 +1151,6 @@ static struct command_result *json_pay(struct command *cmd,
 		}
 		p->payment_metadata = NULL;
 		p->routes = NULL;
-		/* FIXME: paths! */
 		if (b12->cltv)
 			p->min_final_cltv_expiry = *b12->cltv;
 		else
@@ -1161,6 +1190,19 @@ static struct command_result *json_pay(struct command *cmd,
 		p->amount = *msat;
 	}
 
+	/* We replace real final values if we're using a blinded path */
+	if (p->blindedpath) {
+		p->blindedfinalcltv = p->min_final_cltv_expiry;
+		p->blindedfinalamount = p->amount;
+
+		p->min_final_cltv_expiry += p->blindedpay->cltv_expiry_delta;
+		if (!amount_msat_add_fee(&p->amount,
+					 p->blindedpay->fee_base_msat,
+					 p->blindedpay->fee_proportional_millionths))
+			return command_fail(cmd, PAY_ROUTE_TOO_EXPENSIVE,
+					    "This payment blinded path fee overflows!");
+	}
+
 	if (node_id_eq(&my_id, p->destination))
 		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "This payment is destined for ourselves. "

plugins/test/run-route-overlong.c

@@ -8,6 +8,12 @@
 #include <unistd.h>
 
 /* AUTOGENERATED MOCKS START */
+/* Generated stub for blinded_onion_hops */
+u8 **blinded_onion_hops(const tal_t *ctx UNNEEDED,
+			struct amount_msat final_amount UNNEEDED,
+			u32 final_cltv UNNEEDED,
+			const struct blinded_path *path UNNEEDED)
+{ fprintf(stderr, "blinded_onion_hops called!\n"); abort(); }
 /* Generated stub for command_finished */
 struct command_result *command_finished(struct command *cmd UNNEEDED, struct json_stream *response UNNEEDED)
 { fprintf(stderr, "command_finished called!\n"); abort(); }