htlc: Allow for exactly min_final_cltv_expiry cltv delta

We are announcing that we are willing to accept incoming payments with
current_height + min_final_cltv_expiry + slack, assuming that the
sender adds some slack. In particular we'd reject the payment if
slack=0 which is allowed by the spec.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/peer_htlcs.c

@@ -359,9 +359,9 @@ static void handle_localpay(struct htlc_in *hin,
 	 * If the `cltv_expiry` is too low, the final node MUST fail the HTLC:
 	 */
 	if (get_block_height(ld->topology) + ld->config.cltv_final
-	    >= cltv_expiry) {
+	    > cltv_expiry) {
 		log_debug(hin->key.peer->log,
-			  "Expiry cltv %u too close to current %u + %u",
+			  "Expiry cltv too soon %u < %u + %u",
 			  cltv_expiry,
 			  get_block_height(ld->topology),
 			  ld->config.cltv_final);

tests/test_lightningd.py

@@ -299,7 +299,7 @@ class LightningDTests(BaseLightningDTests):
         assert b11['description'] == 'description'
         assert b11['expiry'] == 3600
         assert b11['payee'] == l1.info['id']
-        
+
     def test_connect(self):
         l1,l2 = self.connect()
 
@@ -329,9 +329,9 @@ class LightningDTests(BaseLightningDTests):
         # BOLT #11:
         # > ### Please make a donation of any amount using payment_hash 0001020304050607080900010203040506070809000102030405060708090102 to me @03e7156ae33b0a208d0744199163177e909e80176e55d97a2f221ede0f934dd9ad
         # > lnbc1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqdpl2pkx2ctnv5sxxmmwwd5kgetjypeh2ursdae8g6twvus8g6rfwvs8qun0dfjkxaq8rkx3yf5tcsyz3d73gafnh3cax9rn449d9p5uxz9ezhhypd0elx87sjle52x86fux2ypatgddc6k63n7erqz25le42c4u4ecky03ylcqca784w
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `1`: Bech32 separator
         # * `pvjluez`: timestamp (1496314658)
@@ -350,13 +350,13 @@ class LightningDTests(BaseLightningDTests):
         assert b11['description'] == 'Please consider supporting this project'
         assert b11['expiry'] == 3600
         assert b11['payee'] == '03e7156ae33b0a208d0744199163177e909e80176e55d97a2f221ede0f934dd9ad'
-        
+
         # BOLT #11:
         # > ### Please send $3 for a cup of coffee to the same peer, within 1 minute
         # > lnbc2500u1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqdq5xysxxatsyp3k7enxv4jsxqzpuaztrnwngzn3kdzw5hydlzf03qdgm2hdq27cqv3agm2awhz5se903vruatfhq77w3ls4evs3ch9zw97j25emudupq63nyw24cg27h2rspfj9srp
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `2500u`: amount (2500 micro-bitcoin)
         # * `1`: Bech32 separator
@@ -382,9 +382,9 @@ class LightningDTests(BaseLightningDTests):
         # BOLT #11:
         # > ### Now send $24 for an entire list of things (hashed)
         # > lnbc20m1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqscc6gd6ql3jrc5yzme8v4ntcewwz5cnw92tz0pc8qcuufvq7khhr8wpald05e92xw006sq94mg8v2ndf4sefvf9sygkshp5zfem29trqq2yxxz7
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -405,9 +405,9 @@ class LightningDTests(BaseLightningDTests):
 
         # > ### The same, on testnet, with a fallback address mk2QpYatsKicvFVuTAQLBryyccRXMUaGHP
         # > lntb20m1pvjluezhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqspp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqfpp3x9et2e20v6pu37c5d9vax37wxq72un98kmzzhznpurw9sgl2v0nklu2g4d0keph5t7tj9tcqd8rexnd07ux4uv2cjvcqwaxgj7v4uwn5wmypjd5n69z2xm3xgksg28nwht7f6zspwp3f9t
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lntb`: prefix, lightning on bitcoin testnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -428,12 +428,12 @@ class LightningDTests(BaseLightningDTests):
         assert b11['payee'] == '03e7156ae33b0a208d0744199163177e909e80176e55d97a2f221ede0f934dd9ad'
         assert b11['fallback']['type'] == 'P2PKH'
         assert b11['fallback']['addr'] == 'mk2QpYatsKicvFVuTAQLBryyccRXMUaGHP'
-        
+
         # > ### On mainnet, with fallback address 1RustyRX2oai4EYYDpQGWvEL62BBGqN9T with extra routing info to go via nodes 029e03a901b85534ff1e92c43c74431f7ce72046060fcf7a95c37e148f78c77255 then 039e03a901b85534ff1e92c43c74431f7ce72046060fcf7a95c37e148f78c77255
         # > lnbc20m1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqsfpp3qjmp7lwpagxun9pygexvgpjdc4jdj85fr9yq20q82gphp2nflc7jtzrcazrra7wwgzxqc8u7754cdlpfrmccae92qgzqvzq2ps8pqqqqqqqqqqqq9qqqvpeuqafqxu92d8lr6fvg0r5gv0heeeqgcrqlnm6jhphu9y00rrhy4grqszsvpcgpy9qqqqqqqqqqqq7qqzqfnlkwydm8rg30gjku7wmxmk06sevjp53fmvrcfegvwy7d5443jvyhxsel0hulkstws7vqv400q4j3wgpk4crg49682hr4scqvmad43cqd5m7tf
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -470,12 +470,12 @@ class LightningDTests(BaseLightningDTests):
         assert b11['routes'][0][1]['short_channel_id'] == '197637:395016:2314'
         assert b11['routes'][0][1]['fee'] == 30
         assert b11['routes'][0][1]['cltv_expiry_delta'] == 4
-        
+
         # > ### On mainnet, with fallback (P2SH) address 3EktnHQD7RiAE6uzMj2ZifT9YgRrkSgzQX
         # > lnbc20m1pvjluezhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqspp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqfppj3a24vwu6r8ejrss3axul8rxldph2q7z9kmrgvr7xlaqm47apw3d48zm203kzcq357a4ls9al2ea73r8jcceyjtya6fu5wzzpe50zrge6ulk4nvjcpxlekvmxl6qcs9j3tz0469gq5g658y
-        # 
+        #
         # Breakdown:
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -499,7 +499,7 @@ class LightningDTests(BaseLightningDTests):
 
         # > ### On mainnet, with fallback (P2WPKH) address bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
         # > lnbc20m1pvjluezhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqspp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqfppqw508d6qejxtdg4y5r3zarvary0c5xw7kepvrhrm9s57hejg0p662ur5j5cr03890fa7k2pypgttmh4897d3raaq85a293e9jpuqwl0rnfuwzam7yr8e690nd2ypcq9hlkdwdvycqa0qza8
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -507,7 +507,7 @@ class LightningDTests(BaseLightningDTests):
         # * `p`: payment hash...
         # * `f`: tagged field: fallback address.
         # * `pp`: `data_length` (`p` = 1. 1 * 32 + 1 == 33)
-        # * `q`: 0, so witness version 0.  
+        # * `q`: 0, so witness version 0.
         # * `qw508d6qejxtdg4y5r3zarvary0c5xw7k`: 160 bits = P2WPKH.
         # * `h`: tagged field: hash of description...
         # * `gw6tk8z0p0qdy9ulggx65lvfsg3nxxhqjxuf2fvmkhl9f4jc74gy44d5ua9us509prqz3e7vjxrftn3jnk7nrglvahxf7arye5llphgq`: signature
@@ -524,7 +524,7 @@ class LightningDTests(BaseLightningDTests):
 
         # > ### On mainnet, with fallback (P2WSH) address bc1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qccfmv3
         # > lnbc20m1pvjluezhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqspp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqfp4qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3q28j0v3rwgy9pvjnd48ee2pl8xrpxysd5g44td63g6xcjcu003j3qe8878hluqlvl3km8rm92f5stamd3jw763n3hck0ct7p8wwj463cql26ava
-        # 
+        #
         # * `lnbc`: prefix, lightning on bitcoin mainnet
         # * `20m`: amount (20 milli-bitcoin)
         # * `1`: Bech32 separator
@@ -1426,12 +1426,12 @@ class LightningDTests(BaseLightningDTests):
         #    B
         #   / \
         #  /   \
-        # A     C 
+        # A     C
         #  \   /
         #   \ /
         #    D
         # ```
-        # 
+        #
         # Each advertises the following `cltv_expiry_delta` on its end of every
         # channel:
         #
@@ -1482,7 +1482,7 @@ class LightningDTests(BaseLightningDTests):
             'Received channel_update for channel {}\\(1\\)'.format(c2)])
 
         # BOLT #7:
-        # 
+        #
         # If B were to send 4,999,999 millisatoshi directly to C, it wouldn't
         # charge itself a fee nor add its own `cltv_expiry_delta`, so it would
         # use C's requested `cltv_expiry` of 9.  We also assume it adds a
@@ -1510,14 +1510,14 @@ class LightningDTests(BaseLightningDTests):
         # If A were to send an 4,999,999 millisatoshi to C via B, it needs to
         # pay B the fee it specified in the B->C `channel_update`, calculated as
         # per [HTLC Fees](#htlc_fees):
-        # 
+        #
         # 200 + 4999999 * 2000 / 1000000 = 10199
-        # 
+        #
         # Similarly, it would need to add the `cltv_expiry` from B->C's
         # `channel_update` (20), plus C's requested minimum (9), plus 42 for the
         # "shadow route".  Thus the `update_add_htlc` message from A to B would
         # be:
-        # 
+        #
         #    * `amount_msat`: 5010198
         #    * `cltv_expiry`: current-block-height + 20 + 9 + 42
         #    * `onion_routing_packet`:
@@ -1566,7 +1566,7 @@ class LightningDTests(BaseLightningDTests):
 
         l2.daemon.wait_for_log('WIRE_GOSSIPCTL_HANDLE_PEER')
         l3.daemon.wait_for_log('WIRE_GOSSIPCTL_HANDLE_PEER')
-        
+
         c1 = self.fund_channel(l1, l2, 10**6)
         c2 = self.fund_channel(l2, l3, 10**6)
 
@@ -1631,9 +1631,9 @@ class LightningDTests(BaseLightningDTests):
         # Takes 6 blocks to timeout (cltv-final + 1), but we also give grace period of 1 block.
         bitcoind.rpc.generate(5 + 1)
         assert not l1.daemon.is_in_log('hit deadline')
-        bitcoind.rpc.generate(1)
+        bitcoind.rpc.generate(2)
 
-        l1.daemon.wait_for_log('Offered HTLC 0 SENT_ADD_ACK_REVOCATION cltv {} hit deadline'.format(bitcoind.rpc.getblockcount()-1))
+        l1.daemon.wait_for_log('Offered HTLC 0 SENT_ADD_ACK_REVOCATION cltv .* hit deadline')
         l1.daemon.wait_for_log('sendrawtx exit 0')
         l1.bitcoin.rpc.generate(1)
         l1.daemon.wait_for_log('-> ONCHAIND_OUR_UNILATERAL')
@@ -1668,12 +1668,12 @@ class LightningDTests(BaseLightningDTests):
         # l1 will drop to chain, not reconnect.
         l1.daemon.wait_for_log('dev_disconnect: -WIRE_REVOKE_AND_ACK')
 
-        # Deadline HTLC expity minus 1/2 cltv-expiry delta (rounded up) (== cltv - 3).  ctlv is 5+1.
+        # Deadline HTLC expiry minus 1/2 cltv-expiry delta (rounded up) (== cltv - 3).  ctlv is 5+1.
         bitcoind.rpc.generate(2)
         assert not l2.daemon.is_in_log('hit deadline')
-        bitcoind.rpc.generate(1)
+        bitcoind.rpc.generate(2)
 
-        l2.daemon.wait_for_log('Fulfilled HTLC 0 SENT_REMOVE_COMMIT cltv {} hit deadline'.format(bitcoind.rpc.getblockcount()+3))
+        l2.daemon.wait_for_log('Fulfilled HTLC 0 SENT_REMOVE_COMMIT cltv .* hit deadline')
         l2.daemon.wait_for_log('sendrawtx exit 0')
         l2.bitcoin.rpc.generate(1)
         l2.daemon.wait_for_log('-> ONCHAIND_OUR_UNILATERAL')