commit be56ba50a3acba8c0ae26e333ff0a2df5c43da6a
parent 504f23fcd6f6fef6f095176073375d9494d381f1
Author: Jared Tobin <jared@jtobin.io>
Date: Sat, 10 Oct 2026 13:23:01 +0400
lib, test: identify closes by txid
identify_close compared the legacy serialization of each commitment
with the bytes found on chain. A broadcast commitment is a signed
segwit transaction, so the bytes never matched and a real close went
unrecognised. It now parses the on-chain transaction and compares
txids. The signature is unchanged.
Tests rebuild the BOLT #3 Appendix C commitment with bolt3 and
identify the signed vector as both a local and a remote close.
Diffstat:
2 files changed, 162 insertions(+), 36 deletions(-)
diff --git a/lib/Lightning/Protocol/BOLT5/Detect.hs b/lib/Lightning/Protocol/BOLT5/Detect.hs
@@ -39,16 +39,17 @@ import Lightning.Protocol.BOLT5.Types
-- | Identify the type of channel close from a transaction that
-- spends the funding output.
--
--- Compares the on-chain transaction bytes against the known
--- local and remote commitment transaction serializations
--- (stripped/unsigned) to determine whether it's a local or
--- remote commitment close.
+-- Parses the on-chain transaction and compares its txid against
+-- the txids of the known local and remote commitment
+-- transactions. Comparing txids rather than bytes means the
+-- signed (segwit) serialization found on chain matches the
+-- unsigned commitment.
--
--- Returns 'Nothing' if the transaction doesn't match either
--- commitment. Mutual close and revoked commitment detection
--- require additional checks by the caller (e.g. comparing
--- closing tx format, checking a secret store for older
--- commitment numbers).
+-- Returns 'Nothing' if the bytes don't parse as a transaction or
+-- the transaction doesn't match either commitment. Mutual close
+-- and revoked commitment detection require additional checks by
+-- the caller (e.g. comparing closing tx format, checking a secret
+-- store for older commitment numbers).
identify_close
:: CommitmentTx
-- ^ Our local commitment tx.
@@ -59,13 +60,15 @@ identify_close
-> Maybe CloseType
identify_close !localCommitTx !remoteCommitTx
!onChainBytes =
- let !localBytes = encode_tx_for_signing localCommitTx
- !remoteBytes = encode_tx_for_signing remoteCommitTx
- in if localBytes == Just onChainBytes
- then Just LocalCommitClose
- else if remoteBytes == Just onChainBytes
- then Just RemoteCommitClose
- else Nothing
+ case BT.from_bytes onChainBytes of
+ Nothing -> Nothing
+ Just !onChainTx ->
+ let !onChainTxid = Just (BT.txid onChainTx)
+ in if commitment_txid localCommitTx == onChainTxid
+ then Just LocalCommitClose
+ else if commitment_txid remoteCommitTx == onChainTxid
+ then Just RemoteCommitClose
+ else Nothing
-- output classification ----------------------------------------------
diff --git a/test/Main.hs b/test/Main.hs
@@ -8,7 +8,7 @@ import Bitcoin.Prim.Tx.Sighash (SighashType(..))
import qualified Crypto.Hash.SHA256 as SHA256
import qualified Data.ByteString as BS
import Data.List.NonEmpty (NonEmpty(..))
-import Data.Word (Word8)
+import Data.Word (Word8, Word32, Word64)
import Lightning.Protocol.BOLT3 hiding
(txout_value, txout_script)
import Lightning.Protocol.BOLT3.Types (Pubkey(..), PaymentHash(..))
@@ -200,6 +200,125 @@ dummyRemoteCommitTx = CommitmentTx
vecPaymentHash :: Word8 -> PaymentHash
vecPaymentHash b = PaymentHash (SHA256.hash (BS.replicate 32 b))
+-- | Decode a hex string.
+unhex :: BS.ByteString -> Maybe BS.ByteString
+unhex bs
+ | odd (BS.length bs) = Nothing
+ | otherwise = BS.pack <$> go (BS.unpack bs)
+ where
+ go (a:b:rest) = (:) <$> byte a b <*> go rest
+ go _ = Just []
+ byte a b = (\hi lo -> hi * 16 + lo) <$> nibble a <*> nibble b
+ nibble c
+ | c >= 0x30 && c <= 0x39 = Just (c - 0x30)
+ | c >= 0x61 && c <= 0x66 = Just (c - 0x57)
+ | otherwise = Nothing
+
+-- | An Appendix C HTLC, given its direction, amount (msat), expiry
+-- and preimage byte.
+vecHtlc :: HTLCDirection -> Word64 -> Word32 -> Word8 -> HTLC
+vecHtlc dir msat expiry b = HTLC
+ { htlc_direction = dir
+ , htlc_amount_msat = MilliSatoshi msat
+ , htlc_payment_hash = vecPaymentHash b
+ , htlc_cltv_expiry = CltvExpiry expiry
+ }
+
+vecHtlc1, vecHtlc5, vecHtlc6 :: HTLC
+vecHtlc1 = vecHtlc HTLCReceived 2000000 501 0x01
+vecHtlc5 = vecHtlc HTLCOffered 5000000 506 0x05
+vecHtlc6 = vecHtlc HTLCOffered 5000001 505 0x05
+
+-- | Appendix C keys for the local commitment (Appendix F uses the
+-- same keys).
+vecKeys :: Maybe CommitmentKeys
+vecKeys = do
+ rev <- key
+ "0212a140cd0c6539d07cd08dfe09984dec3251ea808b892efeac3ede9402bf2b19"
+ delayed <- key
+ "03fd5960528dc152014952efdb702a88f71e3c1653b2314431701ec77e57fde83c"
+ localHtlc <- key
+ "030d417a46946384f88d5f3337267c5e579765875dc4daca813e21734b140639e7"
+ remoteHtlc <- key
+ "0394854aa6eab5b2a8122cc726e9dded053a2184d88256816826d6231c068d4a5b"
+ localPayment <- key
+ "034f355bdcb7cc0af728ef3cceb9615d90684bb5b2ca5f859ab0f0b704075871aa"
+ remotePayment <- key
+ "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991"
+ localFunding <- key
+ "023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb"
+ remoteFunding <- key
+ "030e9f7b623d2ccc7c9bd44d66d5ce21ce504c0acf6385a132cec6d3c39fa711c1"
+ pure CommitmentKeys
+ { ck_revocation_pubkey = RevocationPubkey rev
+ , ck_local_delayed = LocalDelayedPubkey delayed
+ , ck_local_htlc = LocalHtlcPubkey localHtlc
+ , ck_remote_htlc = RemoteHtlcPubkey remoteHtlc
+ , ck_local_payment = LocalPubkey localPayment
+ , ck_remote_payment = RemotePubkey remotePayment
+ , ck_local_funding = FundingPubkey localFunding
+ , ck_remote_funding = FundingPubkey remoteFunding
+ }
+ where
+ key h = unhex h >>= pubkey
+
+-- | Rebuild an Appendix C/F local commitment with bolt3, given the
+-- feerate, channel features, to_local balance and HTLCs.
+vecCommitment
+ :: FeeratePerKw -> ChannelFeatures -> MilliSatoshi -> [HTLC]
+ -> Maybe CommitmentTx
+vecCommitment feerate features toLocal htlcs = do
+ keys <- vecKeys
+ fundingTxid <- mkTxId =<< unhex
+ "bef67e4e2fb9ddeeb3461973cd4c62abb35050b1add772995b820b584a488489"
+ cn <- commitment_number 42
+ localBp <- point =<< unhex
+ "034f355bdcb7cc0af728ef3cceb9615d90684bb5b2ca5f859ab0f0b704075871aa"
+ remoteBp <- point =<< unhex
+ "032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991"
+ pure $ build_commitment_tx CommitmentContext
+ { cc_funding_outpoint = OutPoint fundingTxid 0
+ , cc_commitment_number = cn
+ , cc_local_payment_bp = PaymentBasepoint localBp
+ , cc_remote_payment_bp = PaymentBasepoint remoteBp
+ , cc_to_self_delay = ToSelfDelay 144
+ , cc_dust_limit = DustLimit (Satoshi 546)
+ , cc_feerate = feerate
+ , cc_features = features
+ , cc_is_funder = True
+ , cc_to_local_msat = toLocal
+ , cc_to_remote_msat = MilliSatoshi 3000000000
+ , cc_htlcs = htlcs
+ , cc_keys = keys
+ }
+
+-- | The Appendix C commitment with two offered HTLCs sharing a
+-- payment hash and amount.
+vecCommitSameHash :: Maybe CommitmentTx
+vecCommitSameHash = vecCommitment (FeeratePerKw 253)
+ (ChannelFeatures False) (MilliSatoshi 6987999999)
+ [vecHtlc1, vecHtlc5, vecHtlc6]
+
+-- | Appendix C: commitment tx with 3 htlc outputs, 2 offered
+-- having the same amount and preimage (signed).
+vecCCommitSameHash :: BS.ByteString
+vecCCommitSameHash =
+ "02000000000101bef67e4e2fb9ddeeb3461973cd4c62abb35050b1add772995b\
+ \820b584a488489000000000038b02b8005d007000000000000220020748eba94\
+ \4fedc8827f6b06bc44678f93c0f9e6078b35c6331ed31e75f8ce0c2d88130000\
+ \00000000220020305c12e1a0bc21e283c131cea1c66d68857d28b7b2fce0a6fb\
+ \c40c164852121b8813000000000000220020305c12e1a0bc21e283c131cea1c6\
+ \6d68857d28b7b2fce0a6fbc40c164852121bc0c62d0000000000160014cc1b07\
+ \838e387deacd0e5232e1e8b49f4c29e484a69f6a00000000002200204adb4e2f\
+ \00643db396dd120d4e7dc17625f5f2c11a40d857accc862d6b7dd80e04004730\
+ \4402200d10bf5bc5397fc59d7188ae438d80c77575595a2d488e41bd6363a810\
+ \cc8d72022012b57e714fbbfdf7a28c47d5b370cb8ac37c8545f596216e5b21e9\
+ \b236ef457c0147304402207d0870964530f97b62497b11153c551dca0a1e2268\
+ \15ef0a336651158da0f82402200f5378beee0e77759147b8a0a284decd11bfd2\
+ \bc55c8fafa41c134fe996d43c801475221023da092f6980e58d2c037173180e9\
+ \a465476026ee50f96695963e8efe436f54eb21030e9f7b623d2ccc7c9bd44d66\
+ \d5ce21ce504c0acf6385a132cec6d3c39fa711c152ae3e195220"
+
-- | Appendix C: HTLC-success tx for htlc #1 from the same
-- commitment (signed).
vecCHtlcSuccess1 :: BS.ByteString
@@ -386,27 +505,31 @@ detect_tests = testGroup "Detect" [
classify_tests :: TestTree
classify_tests = testGroup "Classify" [
- testCase "identify_close - local commit" $ do
- case encode_tx_for_signing dummyLocalCommitTx of
- Nothing -> assertFailure "encode failed"
- Just localBytes ->
- B5.identify_close
- dummyLocalCommitTx
- dummyRemoteCommitTx
- localBytes
- @?= Just B5.LocalCommitClose
-
- , testCase "identify_close - remote commit" $ do
- case encode_tx_for_signing dummyRemoteCommitTx of
- Nothing -> assertFailure "encode failed"
- Just remoteBytes ->
- B5.identify_close
- dummyLocalCommitTx
- dummyRemoteCommitTx
- remoteBytes
- @?= Just B5.RemoteCommitClose
+ testCase "identify_close - signed local commitment" $ do
+ commit <- assertJust "commitment" vecCommitSameHash
+ signed <- assertJust "hex" (unhex vecCCommitSameHash)
+ B5.identify_close commit dummyRemoteCommitTx signed
+ @?= Just B5.LocalCommitClose
+
+ , testCase "identify_close - signed remote commitment" $ do
+ commit <- assertJust "commitment" vecCommitSameHash
+ signed <- assertJust "hex" (unhex vecCCommitSameHash)
+ B5.identify_close dummyLocalCommitTx commit signed
+ @?= Just B5.RemoteCommitClose
+
+ , testCase "identify_close - unsigned commitment" $ do
+ commit <- assertJust "commitment" vecCommitSameHash
+ unsigned <- assertJust "encode" (encode_tx_for_signing commit)
+ B5.identify_close commit dummyRemoteCommitTx unsigned
+ @?= Just B5.LocalCommitClose
, testCase "identify_close - no match" $ do
+ signed <- assertJust "hex" (unhex vecCCommitSameHash)
+ B5.identify_close
+ dummyLocalCommitTx dummyRemoteCommitTx signed
+ @?= Nothing
+
+ , testCase "identify_close - unparseable" $ do
B5.identify_close
dummyLocalCommitTx
dummyRemoteCommitTx
