gossipd: parse and respect optional htlc_maximum_msat

If another channel has set the optional `htlc_maximum_msat` field,
we should correctly parse that field and respect it when drawing up
routes for payments.

Makefile

@@ -9,7 +9,7 @@ CCANDIR := ccan
 
 # Where we keep the BOLT RFCs
 BOLTDIR := ../lightning-rfc/
-BOLTVERSION := 0891374d47ddffa64c5a2e6ad151247e3d6b7a59
+BOLTVERSION := b6ae60d24138a3601561fbc1c9d82d983595ae4f
 
 -include config.vars
 

gossipd/gossip_constants.h

@@ -23,6 +23,16 @@
 #define ROUTING_FLAGS_DIRECTION (1 << 0)
 #define ROUTING_FLAGS_DISABLED  (1 << 1)
 
+/* BOLT #7:
+ *
+ * The `message_flags` bitfield is used to indicate the presence of optional
+ * fields in the `channel_update` message:
+ * | Bit Position  | Name                      | Field                |
+ * | ------------- | ------------------------- | -------------------- |
+ * | 0             | `option_channel_htlc_max` | `htlc_maximum_msat`  |
+ */
+#define ROUTING_OPT_HTLC_MAX_MSAT (1 << 0)
+
 /* BOLT #7:
  *
  * - MUST NOT send `announcement_signatures` messages until `funding_locked`

gossipd/routing.c

@@ -361,6 +361,15 @@ static u64 risk_fee(u64 amount, u32 delay, double riskfactor)
 	return 1 + amount * delay * riskfactor;
 }
 
+/* Check that we can fit through this channel's indicated
+ * maximum_ and minimum_msat requirements.
+ */
+static bool hc_can_carry(const struct half_chan *hc, u64 requiredcap)
+{
+	return hc->htlc_maximum_msat >= requiredcap &&
+		hc->htlc_minimum_msat <= requiredcap;
+}
+
 /* We track totals, rather than costs.  That's because the fee depends
  * on the current amount passing through. */
 static void bfg_one_edge(struct node *node,
@@ -398,13 +407,9 @@ static void bfg_one_edge(struct node *node,
 		risk = node->bfg[h].risk +
 		       risk_fee(requiredcap, c->delay, riskfactor);
 
-		if (requiredcap > chan->satoshis * 1000) {
-			/* Skip this edge if the channel has insufficient
-			 * capacity to route the required amount */
-			continue;
-		} else if (requiredcap < c->htlc_minimum_msat) {
-			/* Skip a channels if it indicated that it won't route
-			 * the requeuested amount. */
+		if (!hc_can_carry(c, requiredcap)) {
+			/* Skip a channel if it indicated that it won't route
+			 * the requested amount. */
 			continue;
 		} else if (requiredcap >= MAX_MSATOSHI) {
 			SUPERVERBOSE("...extreme %"PRIu64
@@ -1009,12 +1014,14 @@ static void set_connection_values(struct chan *chan,
 				  u8 message_flags,
 				  u8 channel_flags,
 				  u64 timestamp,
-				  u32 htlc_minimum_msat)
+				  u64 htlc_minimum_msat,
+				  u64 htlc_maximum_msat)
 {
 	struct half_chan *c = &chan->half[idx];
 
 	c->delay = delay;
 	c->htlc_minimum_msat = htlc_minimum_msat;
+	c->htlc_maximum_msat = htlc_maximum_msat;
 	c->base_fee = base_fee;
 	c->proportional_fee = proportional_fee;
 	c->message_flags = message_flags;
@@ -1051,15 +1058,17 @@ bool routing_add_channel_update(struct routing_state *rstate,
 	u64 htlc_minimum_msat;
 	u32 fee_base_msat;
 	u32 fee_proportional_millionths;
+	u64 htlc_maximum_msat;
 	struct bitcoin_blkid chain_hash;
 	struct chan *chan;
 	u8 direction;
 
-	if (!fromwire_channel_update(update, &signature, &chain_hash,
+	if (!fromwire_channel_update_option_channel_htlc_max(update, &signature, &chain_hash,
 				     &short_channel_id, &timestamp,
 				     &message_flags, &channel_flags,
 				     &expiry, &htlc_minimum_msat, &fee_base_msat,
-				     &fee_proportional_millionths))
+				     &fee_proportional_millionths,
+				     &htlc_maximum_msat))
 		return false;
 	chan = get_channel(rstate, &short_channel_id);
 	if (!chan)
@@ -1069,7 +1078,8 @@ bool routing_add_channel_update(struct routing_state *rstate,
 	set_connection_values(chan, direction, fee_base_msat,
 			      fee_proportional_millionths, expiry,
 			      message_flags, channel_flags,
-			      timestamp, htlc_minimum_msat);
+			      timestamp, htlc_minimum_msat,
+			      htlc_maximum_msat);
 
 	/* Replace any old one. */
 	tal_free(chan->half[direction].channel_update);

gossipd/routing.h

@@ -29,6 +29,9 @@ struct half_chan {
 	/* Minimum number of msatoshi in an HTLC */
 	u32 htlc_minimum_msat;
 
+	/* Maximum number of msatoshis in an HTLC */
+	u64 htlc_maximum_msat;
+
 	/* Flags as specified by the `channel_update`s, among other
 	 * things indicated direction wrt the `channel_id` */
 	u8 channel_flags;

gossipd/test/run-bench-find_route.c

@@ -65,6 +65,9 @@ bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNE
 /* Generated stub for fromwire_channel_update */
 bool fromwire_channel_update(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
+/* Generated stub for fromwire_channel_update_option_channel_htlc_max */
+bool fromwire_channel_update_option_channel_htlc_max(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED, u64 *htlc_maximum_msat UNNEEDED)
+{ fprintf(stderr, "fromwire_channel_update_option_channel_htlc_max called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_local_add_channel */
 bool fromwire_gossip_local_add_channel(const void *p UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *remote_node_id UNNEEDED, u64 *satoshis UNNEEDED)
 { fprintf(stderr, "fromwire_gossip_local_add_channel called!\n"); abort(); }

gossipd/test/run-find_route-specific.c

@@ -29,6 +29,9 @@ bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNE
 /* Generated stub for fromwire_channel_update */
 bool fromwire_channel_update(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
+/* Generated stub for fromwire_channel_update_option_channel_htlc_max */
+bool fromwire_channel_update_option_channel_htlc_max(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED, u64 *htlc_maximum_msat UNNEEDED)
+{ fprintf(stderr, "fromwire_channel_update_option_channel_htlc_max called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_local_add_channel */
 bool fromwire_gossip_local_add_channel(const void *p UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *remote_node_id UNNEEDED, u64 *satoshis UNNEEDED)
 { fprintf(stderr, "fromwire_gossip_local_add_channel called!\n"); abort(); }
@@ -126,8 +129,9 @@ get_or_make_connection(struct routing_state *rstate,
 	/* Make sure it's seen as initialized (update non-NULL). */
 	chan->half[idx].channel_update = (void *)chan;
 	chan->half[idx].htlc_minimum_msat = 0;
+	chan->half[idx].htlc_maximum_msat = satoshis * 1000;
 
-	return &chan->half[pubkey_idx(from_id, to_id)];
+	return &chan->half[idx];
 }
 
 static bool channel_is_between(const struct chan *chan,
@@ -151,7 +155,7 @@ int main(void)
 	static const struct bitcoin_blkid zerohash;
 	struct half_chan *nc;
 	struct routing_state *rstate;
-	struct pubkey a, b, c;
+	struct pubkey a, b, c, d;
 	u64 fee;
 	struct chan **route;
 	const double riskfactor = 1.0 / BLOCKS_PER_YEAR / 10000;
@@ -169,6 +173,9 @@ int main(void)
 	pubkey_from_hexstr("02ea622d5c8d6143f15ed3ce1d501dd0d3d09d3b1c83a44d0034949f8a9ab60f06",
 			   strlen("02ea622d5c8d6143f15ed3ce1d501dd0d3d09d3b1c83a44d0034949f8a9ab60f06"),
 			   &c);
+	pubkey_from_hexstr("02cca6c5c966fcf61d121e3a70e03a1cd9eeeea024b26ea666ce974d43b242e636",
+			   strlen("02cca6c5c966fcf61d121e3a70e03a1cd9eeeea024b26ea666ce974d43b242e636"),
+			   &d);
 
 	rstate = new_routing_state(tmpctx, &zerohash, &a, 0);
 
@@ -226,11 +233,31 @@ int main(void)
 	route = find_route(tmpctx, rstate, &a, &c, 999999, riskfactor, 0.0, NULL, &fee);
 	assert(!route);
 
-	/* This should fail to returns a route because it is smaller than these
+	/* 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);
 	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}, */
+	nc = get_or_make_connection(rstate, &a, &d, "6991:2:1", 1000);
+	nc->base_fee = 0;
+	nc->proportional_fee = 0;
+	nc->delay = 5;
+	nc->channel_flags = 0;
+	nc->message_flags = 1;
+	nc->last_timestamp = 1504064344;
+	nc->htlc_minimum_msat = 100;
+	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);
+	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);
+	assert(!route);
+
 	tal_free(tmpctx);
 	secp256k1_context_destroy(secp256k1_ctx);
 	return 0;

gossipd/test/run-find_route.c

@@ -27,6 +27,9 @@ bool fromwire_channel_announcement(const tal_t *ctx UNNEEDED, const void *p UNNE
 /* Generated stub for fromwire_channel_update */
 bool fromwire_channel_update(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED)
 { fprintf(stderr, "fromwire_channel_update called!\n"); abort(); }
+/* Generated stub for fromwire_channel_update_option_channel_htlc_max */
+bool fromwire_channel_update_option_channel_htlc_max(const void *p UNNEEDED, secp256k1_ecdsa_signature *signature UNNEEDED, struct bitcoin_blkid *chain_hash UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, u32 *timestamp UNNEEDED, u8 *message_flags UNNEEDED, u8 *channel_flags UNNEEDED, u16 *cltv_expiry_delta UNNEEDED, u64 *htlc_minimum_msat UNNEEDED, u32 *fee_base_msat UNNEEDED, u32 *fee_proportional_millionths UNNEEDED, u64 *htlc_maximum_msat UNNEEDED)
+{ fprintf(stderr, "fromwire_channel_update_option_channel_htlc_max called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_local_add_channel */
 bool fromwire_gossip_local_add_channel(const void *p UNNEEDED, struct short_channel_id *short_channel_id UNNEEDED, struct pubkey *remote_node_id UNNEEDED, u64 *satoshis UNNEEDED)
 { fprintf(stderr, "fromwire_gossip_local_add_channel called!\n"); abort(); }
@@ -112,14 +115,15 @@ static void add_connection(struct routing_state *rstate,
 	struct short_channel_id scid;
 	struct half_chan *c;
 	struct chan *chan;
+	int satoshis = 100000;
 
 	/* Make a unique scid. */
 	memcpy(&scid, from, sizeof(scid) / 2);
 	memcpy((char *)&scid + sizeof(scid) / 2, to, sizeof(scid) / 2);
 
 	chan = get_channel(rstate, &scid);
 	if (!chan)
-		chan = new_chan(rstate, &scid, from, to, 100000);
+		chan = new_chan(rstate, &scid, from, to, satoshis);
 
 	c = &chan->half[pubkey_idx(from, to)];
 	/* Make sure it's seen as initialized (update non-NULL). */
@@ -129,6 +133,7 @@ static void add_connection(struct routing_state *rstate,
 	c->delay = delay;
 	c->channel_flags = get_channel_direction(from, to);
 	c->htlc_minimum_msat = 0;
+	c->htlc_maximum_msat = satoshis * 1000;
 }
 
 /* Returns chan connecting from and to: *idx set to refer

lightningd/test/run-invoice-select-inchan.c

@@ -71,7 +71,7 @@ void delay_then_reconnect(struct channel *channel UNNEEDED, u32 seconds_delay UN
 void   fatal(const char *fmt UNNEEDED, ...)
 { fprintf(stderr, "fatal called!\n"); abort(); }
 /* Generated stub for fromwire_connect_peer_connected */
-bool fromwire_connect_peer_connected(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct pubkey *id UNNEEDED, struct wireaddr_internal *addr UNNEEDED, struct crypto_state *crypto_state UNNEEDED, u8 **gfeatures UNNEEDED, u8 **lfeatures UNNEEDED)
+bool fromwire_connect_peer_connected(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct pubkey *id UNNEEDED, struct wireaddr_internal *addr UNNEEDED, struct crypto_state *crypto_state UNNEEDED, u8 **globalfeatures UNNEEDED, u8 **localfeatures UNNEEDED)
 { fprintf(stderr, "fromwire_connect_peer_connected called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_get_incoming_channels_reply */
 bool fromwire_gossip_get_incoming_channels_reply(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct route_info **route_info UNNEEDED)

wallet/test/run-wallet.c

@@ -83,7 +83,7 @@ bool fromwire_channel_offer_htlc_reply(const tal_t *ctx UNNEEDED, const void *p
 bool fromwire_channel_sending_commitsig(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, u64 *commitnum UNNEEDED, u32 *feerate UNNEEDED, struct changed_htlc **changed UNNEEDED, secp256k1_ecdsa_signature *commit_sig UNNEEDED, secp256k1_ecdsa_signature **htlc_sigs UNNEEDED)
 { fprintf(stderr, "fromwire_channel_sending_commitsig called!\n"); abort(); }
 /* Generated stub for fromwire_connect_peer_connected */
-bool fromwire_connect_peer_connected(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct pubkey *id UNNEEDED, struct wireaddr_internal *addr UNNEEDED, struct crypto_state *crypto_state UNNEEDED, u8 **gfeatures UNNEEDED, u8 **lfeatures UNNEEDED)
+bool fromwire_connect_peer_connected(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct pubkey *id UNNEEDED, struct wireaddr_internal *addr UNNEEDED, struct crypto_state *crypto_state UNNEEDED, u8 **globalfeatures UNNEEDED, u8 **localfeatures UNNEEDED)
 { fprintf(stderr, "fromwire_connect_peer_connected called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_resolve_channel_reply */
 bool fromwire_gossip_resolve_channel_reply(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct pubkey **keys UNNEEDED)

wire/gen_peer_wire_csv

@@ -149,6 +149,7 @@ channel_update,110,cltv_expiry_delta,2
 channel_update,112,htlc_minimum_msat,8
 channel_update,120,fee_base_msat,4
 channel_update,124,fee_proportional_millionths,4
+channel_update,128,htlc_maximum_msat,8,option_channel_htlc_max
 query_short_channel_ids,261
 query_short_channel_ids,0,chain_hash,32
 query_short_channel_ids,32,len,2