gossipd: handle receipt of modern onion message.

And wire it through to the hook; update the plugins to recognize
modern vs obs2 onions.

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

gossipd/gossipd.c

@@ -458,6 +458,7 @@ static u8 *handle_obs2_onion_message(struct peer *peer, const u8 *msg)
 		towire_tlvstream_raw(&omsg, om->fields);
 		daemon_conn_send(peer->daemon->master,
 				 take(towire_gossipd_got_onionmsg_to_us(NULL,
+							true, /* obs2 */
 							&alias, self_id,
 							reply_blinding,
 							first_node_id,
@@ -527,7 +528,148 @@ static struct io_plan *onionmsg_req(struct io_conn *conn, struct daemon *daemon,
 /* Peer sends an onion msg. */
 static u8 *handle_onion_message(struct peer *peer, const u8 *msg)
 {
-	/* FIXME! */
+	enum onion_wire badreason;
+	struct onionpacket *op;
+	struct pubkey blinding, ephemeral;
+	struct route_step *rs;
+	u8 *onion;
+	struct tlv_onionmsg_payload *om;
+	struct secret ss, onion_ss;
+	const u8 *cursor;
+	size_t max, maxlen;
+
+	/* Ignore unless explicitly turned on. */
+	if (!feature_offered(peer->daemon->our_features->bits[NODE_ANNOUNCE_FEATURE],
+			     OPT_ONION_MESSAGES))
+		return NULL;
+
+	/* FIXME: ratelimit! */
+	if (!fromwire_onion_message(msg, msg, &blinding, &onion))
+		return towire_warningfmt(peer, NULL, "Bad onion_message");
+
+	/* We unwrap the onion now. */
+	op = parse_onionpacket(tmpctx, onion, tal_bytelen(onion), &badreason);
+	if (!op) {
+		status_peer_debug(&peer->id, "onion msg: can't parse onionpacket: %s",
+				  onion_wire_name(badreason));
+		return NULL;
+	}
+
+	ephemeral = op->ephemeralkey;
+	if (!unblind_onion(&blinding, ecdh, &ephemeral, &ss)) {
+		status_peer_debug(&peer->id, "onion msg: can't unblind onionpacket");
+		return NULL;
+	}
+
+	/* Now get onion shared secret and parse it. */
+	ecdh(&ephemeral, &onion_ss);
+	rs = process_onionpacket(tmpctx, op, &onion_ss, NULL, 0, false);
+	if (!rs) {
+		status_peer_debug(&peer->id,
+				  "onion msg: can't process onionpacket ss=%s",
+				  type_to_string(tmpctx, struct secret, &onion_ss));
+		return NULL;
+	}
+
+	/* The raw payload is prepended with length in the modern onion. */
+	cursor = rs->raw_payload;
+	max = tal_bytelen(rs->raw_payload);
+	maxlen = fromwire_bigsize(&cursor, &max);
+	if (!cursor) {
+		status_peer_debug(&peer->id, "onion msg: Invalid hop payload %s",
+				  tal_hex(tmpctx, rs->raw_payload));
+		return NULL;
+	}
+	if (maxlen > max) {
+		status_peer_debug(&peer->id, "onion msg: overlong hop payload %s",
+				  tal_hex(tmpctx, rs->raw_payload));
+		return NULL;
+	}
+
+	om = tlv_onionmsg_payload_new(msg);
+	if (!fromwire_onionmsg_payload(&cursor, &maxlen, om)) {
+		status_peer_debug(&peer->id, "onion msg: invalid onionmsg_payload %s",
+				  tal_hex(tmpctx, rs->raw_payload));
+		return NULL;
+	}
+
+	if (rs->nextcase == ONION_END) {
+		struct pubkey *reply_blinding, *first_node_id, me, alias;
+		const struct onionmsg_path **reply_path;
+		struct secret *self_id;
+		u8 *omsg;
+
+		if (!pubkey_from_node_id(&me, &peer->daemon->id)) {
+			status_broken("Failed to convert own id");
+			return NULL;
+		}
+
+		/* Final enctlv is actually optional */
+		if (!om->encrypted_data_tlv) {
+			alias = me;
+			self_id = NULL;
+		} else if (!decrypt_final_enctlv(tmpctx, &blinding, &ss,
+						 om->encrypted_data_tlv, &me, &alias,
+						 &self_id)) {
+			status_peer_debug(&peer->id,
+					  "onion msg: failed to decrypt enctlv"
+					  " %s", tal_hex(tmpctx, om->encrypted_data_tlv));
+			return NULL;
+		}
+
+		if (om->reply_path) {
+			first_node_id = &om->reply_path->first_node_id;
+			reply_blinding = &om->reply_path->blinding;
+			reply_path = cast_const2(const struct onionmsg_path **,
+						 om->reply_path->path);
+		} else {
+			first_node_id = NULL;
+			reply_blinding = NULL;
+			reply_path = NULL;
+		}
+
+		/* We re-marshall here by policy, before handing to lightningd */
+		omsg = tal_arr(tmpctx, u8, 0);
+		towire_tlvstream_raw(&omsg, om->fields);
+		daemon_conn_send(peer->daemon->master,
+				 take(towire_gossipd_got_onionmsg_to_us(NULL,
+							false, /* !obs2 */
+							&alias, self_id,
+							reply_blinding,
+							first_node_id,
+							reply_path,
+							omsg)));
+	} else {
+		struct pubkey next_node, next_blinding;
+		struct peer *next_peer;
+		struct node_id next_node_id;
+
+		/* This fails as expected if no enctlv. */
+		if (!decrypt_enctlv(&blinding, &ss, om->encrypted_data_tlv, &next_node,
+					 &next_blinding)) {
+			status_peer_debug(&peer->id,
+					  "onion msg: invalid enctlv %s",
+					  tal_hex(tmpctx, om->encrypted_data_tlv));
+			return NULL;
+		}
+
+		/* FIXME: Handle short_channel_id! */
+		node_id_from_pubkey(&next_node_id, &next_node);
+		next_peer = find_peer(peer->daemon, &next_node_id);
+		if (!next_peer) {
+			status_peer_debug(&peer->id,
+					  "onion msg: unknown next peer %s",
+					  type_to_string(tmpctx,
+							 struct pubkey,
+							 &next_node));
+			return NULL;
+		}
+		queue_peer_msg(next_peer,
+			       take(towire_onion_message(NULL,
+							 &next_blinding,
+							 serialize_onionpacket(tmpctx, rs->next))));
+	}
+
 	return NULL;
 }
 

gossipd/gossipd_wire.csv

@@ -75,6 +75,7 @@ msgtype,gossipd_new_blockheight,3026
 msgdata,gossipd_new_blockheight,blockheight,u32,
 
 msgtype,gossipd_got_onionmsg_to_us,3145
+msgdata,gossipd_got_onionmsg_to_us,obs2,bool,
 msgdata,gossipd_got_onionmsg_to_us,node_alias,pubkey,
 msgdata,gossipd_got_onionmsg_to_us,self_id,?secret,
 msgdata,gossipd_got_onionmsg_to_us,reply_blinding,?pubkey,

lightningd/onion_message.c

@@ -21,7 +21,9 @@ struct onion_message_hook_payload {
 	struct pubkey *reply_first_node;
 	struct pubkey *our_alias;
 
-	struct tlv_obs2_onionmsg_payload *om;
+	/* Exactly one of these is set! */
+	struct tlv_onionmsg_payload *om;
+	struct tlv_obs2_onionmsg_payload *obs2_om;
 };
 
 static void json_add_blindedpath(struct json_stream *stream,
@@ -61,28 +63,55 @@ static void onion_message_serialize(struct onion_message_hook_payload *payload,
 	}
 
 	/* Common convenience fields */
-	if (payload->om->invoice_request)
-		json_add_hex_talarr(stream, "invoice_request",
-				    payload->om->invoice_request);
-	if (payload->om->invoice)
-		json_add_hex_talarr(stream, "invoice", payload->om->invoice);
+	if (payload->obs2_om) {
+		json_add_bool(stream, "obs2", true);
+		if (payload->obs2_om->invoice_request)
+			json_add_hex_talarr(stream, "invoice_request",
+					    payload->obs2_om->invoice_request);
+		if (payload->obs2_om->invoice)
+			json_add_hex_talarr(stream, "invoice", payload->obs2_om->invoice);
 
-	if (payload->om->invoice_error)
-		json_add_hex_talarr(stream, "invoice_error",
-				    payload->om->invoice_error);
+		if (payload->obs2_om->invoice_error)
+			json_add_hex_talarr(stream, "invoice_error",
+					    payload->obs2_om->invoice_error);
 
-	json_array_start(stream, "unknown_fields");
-	for (size_t i = 0; i < tal_count(payload->om->fields); i++) {
-		if (payload->om->fields[i].meta)
-			continue;
-		json_object_start(stream, NULL);
-		json_add_u64(stream, "number", payload->om->fields[i].numtype);
-		json_add_hex(stream, "value",
-			     payload->om->fields[i].value,
-			     payload->om->fields[i].length);
-		json_object_end(stream);
+		json_array_start(stream, "unknown_fields");
+		for (size_t i = 0; i < tal_count(payload->obs2_om->fields); i++) {
+			if (payload->obs2_om->fields[i].meta)
+				continue;
+			json_object_start(stream, NULL);
+			json_add_u64(stream, "number", payload->obs2_om->fields[i].numtype);
+			json_add_hex(stream, "value",
+				     payload->obs2_om->fields[i].value,
+				     payload->obs2_om->fields[i].length);
+			json_object_end(stream);
+		}
+		json_array_end(stream);
+	} else {
+		json_add_bool(stream, "obs2", false);
+		if (payload->om->invoice_request)
+			json_add_hex_talarr(stream, "invoice_request",
+					    payload->om->invoice_request);
+		if (payload->om->invoice)
+			json_add_hex_talarr(stream, "invoice", payload->om->invoice);
+
+		if (payload->om->invoice_error)
+			json_add_hex_talarr(stream, "invoice_error",
+					    payload->om->invoice_error);
+
+		json_array_start(stream, "unknown_fields");
+		for (size_t i = 0; i < tal_count(payload->om->fields); i++) {
+			if (payload->om->fields[i].meta)
+				continue;
+			json_object_start(stream, NULL);
+			json_add_u64(stream, "number", payload->om->fields[i].numtype);
+			json_add_hex(stream, "value",
+				     payload->om->fields[i].value,
+				     payload->om->fields[i].length);
+			json_object_end(stream);
+		}
+		json_array_end(stream);
 	}
-	json_array_end(stream);
 	json_object_end(stream);
 }
 
@@ -113,14 +142,15 @@ void handle_onionmsg_to_us(struct lightningd *ld, const u8 *msg)
 	struct onion_message_hook_payload *payload;
 	u8 *submsg;
 	struct secret *self_id;
+	bool obs2;
 	size_t submsglen;
 	const u8 *subptr;
 
 	payload = tal(ld, struct onion_message_hook_payload);
-	payload->om = tlv_obs2_onionmsg_payload_new(payload);
 	payload->our_alias = tal(payload, struct pubkey);
 
 	if (!fromwire_gossipd_got_onionmsg_to_us(payload, msg,
+						 &obs2,
 						 payload->our_alias,
 						 &self_id,
 						 &payload->reply_blinding,
@@ -139,12 +169,25 @@ void handle_onionmsg_to_us(struct lightningd *ld, const u8 *msg)
 
 	submsglen = tal_bytelen(submsg);
 	subptr = submsg;
-	if (!fromwire_obs2_onionmsg_payload(&subptr,
-					    &submsglen, payload->om)) {
-		tal_free(payload);
-		log_broken(ld->log, "bad got_onionmsg_tous om: %s",
-			   tal_hex(tmpctx, msg));
-		return;
+	if (obs2) {
+		payload->om = NULL;
+		payload->obs2_om = tlv_obs2_onionmsg_payload_new(payload);
+		if (!fromwire_obs2_onionmsg_payload(&subptr,
+						    &submsglen, payload->obs2_om)) {
+			tal_free(payload);
+			log_broken(ld->log, "bad got_onionmsg_tous obs2 om: %s",
+				   tal_hex(tmpctx, msg));
+			return;
+		}
+	} else {
+		payload->obs2_om = NULL;
+		payload->om = tlv_onionmsg_payload_new(payload);
+		if (!fromwire_onionmsg_payload(&subptr, &submsglen, payload->om)) {
+			tal_free(payload);
+			log_broken(ld->log, "bad got_onionmsg_tous om: %s",
+				   tal_hex(tmpctx, msg));
+			return;
+		}
 	}
 	tal_free(submsg);
 

plugins/offers.c

@@ -140,7 +140,8 @@ static struct command_result *onion_message_modern_call(struct command *cmd,
 							const jsmntok_t *params)
 {
 	const jsmntok_t *om, *replytok, *invreqtok, *invtok;
-	struct tlv_obs2_onionmsg_payload_reply_path *reply_path;
+	struct tlv_obs2_onionmsg_payload_reply_path *obs2_reply_path = NULL;
+	struct tlv_onionmsg_payload_reply_path *reply_path = NULL;
 
 	if (!offers_enabled)
 		return command_hook_success(cmd);
@@ -148,21 +149,31 @@ static struct command_result *onion_message_modern_call(struct command *cmd,
 	om = json_get_member(buf, params, "onion_message");
 	replytok = json_get_member(buf, om, "reply_blindedpath");
 	if (replytok) {
-		reply_path = json_to_obs2_reply_path(cmd, buf, replytok);
-		if (!reply_path)
-			plugin_err(cmd->plugin, "Invalid reply path %.*s?",
-				   json_tok_full_len(replytok),
-				   json_tok_full(buf, replytok));
-	} else
-		reply_path = NULL;
+		bool obs2;
+		json_to_bool(buf, json_get_member(buf, om, "obs2"), &obs2);
+		if (obs2) {
+			obs2_reply_path = json_to_obs2_reply_path(cmd, buf, replytok);
+			if (!obs2_reply_path)
+				plugin_err(cmd->plugin, "Invalid obs2 reply path %.*s?",
+					   json_tok_full_len(replytok),
+					   json_tok_full(buf, replytok));
+		} else {
+			reply_path = json_to_reply_path(cmd, buf, replytok);
+			if (!reply_path)
+				plugin_err(cmd->plugin, "Invalid reply path %.*s?",
+					   json_tok_full_len(replytok),
+					   json_tok_full(buf, replytok));
+		}
+	}
 
 	invreqtok = json_get_member(buf, om, "invoice_request");
 	if (invreqtok) {
 		const u8 *invreqbin = json_tok_bin_from_hex(tmpctx, buf, invreqtok);
-		if (reply_path)
+		if (reply_path || obs2_reply_path)
 			return handle_invoice_request(cmd,
 						      invreqbin,
-						      reply_path);
+						      reply_path,
+						      obs2_reply_path);
 		else
 			plugin_log(cmd->plugin, LOG_DBG,
 				   "invoice_request without reply_path");
@@ -172,7 +183,7 @@ static struct command_result *onion_message_modern_call(struct command *cmd,
 	if (invtok) {
 		const u8 *invbin = json_tok_bin_from_hex(tmpctx, buf, invtok);
 		if (invbin)
-			return handle_invoice(cmd, invbin, reply_path);
+			return handle_invoice(cmd, invbin, reply_path, obs2_reply_path);
 	}
 
 	return command_hook_success(cmd);

plugins/offers_inv_hook.c

@@ -315,7 +315,8 @@ static struct command_result *listoffers_error(struct command *cmd,
 
 struct command_result *handle_invoice(struct command *cmd,
 				      const u8 *invbin,
-				      struct tlv_obs2_onionmsg_payload_reply_path *reply_path STEALS)
+				      struct tlv_onionmsg_payload_reply_path *reply_path STEALS,
+				      struct tlv_obs2_onionmsg_payload_reply_path *obs2_reply_path STEALS)
 {
 	size_t len = tal_count(invbin);
 	struct inv *inv = tal(cmd, struct inv);
@@ -324,8 +325,8 @@ struct command_result *handle_invoice(struct command *cmd,
 	int bad_feature;
 	struct sha256 m, shash;
 
-	inv->obs2_reply_path = tal_steal(inv, reply_path);
-	inv->reply_path = NULL;
+	inv->obs2_reply_path = tal_steal(inv, obs2_reply_path);
+	inv->reply_path = tal_steal(inv, reply_path);
 
 	inv->inv = tlv_invoice_new(cmd);
 	if (!fromwire_invoice(&invbin, &len, inv->inv)) {

plugins/offers_inv_hook.h

@@ -6,5 +6,6 @@
 /* We got an onionmessage with an invoice!  reply_path could be NULL. */
 struct command_result *handle_invoice(struct command *cmd,
 				      const u8 *invbin,
-				      struct tlv_obs2_onionmsg_payload_reply_path *reply_path STEALS);
+				      struct tlv_onionmsg_payload_reply_path *reply_path STEALS,
+				      struct tlv_obs2_onionmsg_payload_reply_path *obs2_reply_path STEALS);
 #endif /* LIGHTNING_PLUGINS_OFFERS_INV_HOOK_H */

plugins/offers_invreq_hook.c

@@ -833,15 +833,16 @@ static struct command_result *handle_offerless_request(struct command *cmd,
 
 struct command_result *handle_invoice_request(struct command *cmd,
 					      const u8 *invreqbin,
-					      struct tlv_obs2_onionmsg_payload_reply_path *reply_path)
+					      struct tlv_onionmsg_payload_reply_path *reply_path,
+					      struct tlv_obs2_onionmsg_payload_reply_path *obs2_reply_path)
 {
 	size_t len = tal_count(invreqbin);
 	struct invreq *ir = tal(cmd, struct invreq);
 	struct out_req *req;
 	int bad_feature;
 
-	ir->obs2_reply_path = tal_steal(ir, reply_path);
-	ir->reply_path = NULL;
+	ir->obs2_reply_path = tal_steal(ir, obs2_reply_path);
+	ir->reply_path = tal_steal(ir, reply_path);
 
 	ir->invreq = tlv_invoice_request_new(cmd);
 	if (!fromwire_invoice_request(&invreqbin, &len, ir->invreq)) {

plugins/offers_invreq_hook.h

@@ -8,5 +8,6 @@ extern u32 cltv_final;
 /* We got an onionmessage with an invreq! */
 struct command_result *handle_invoice_request(struct command *cmd,
 					      const u8 *invreqbin,
-					      struct tlv_obs2_onionmsg_payload_reply_path *reply_path STEALS);
+					      struct tlv_onionmsg_payload_reply_path *reply_path STEALS,
+					      struct tlv_obs2_onionmsg_payload_reply_path *obs2_reply_path STEALS);
 #endif /* LIGHTNING_PLUGINS_OFFERS_INVREQ_HOOK_H */