bolt4

commit 465574655161f2e2bd196b3d7b863c8e916cce16
parent b5939c2e8d40e1a2a840b87dd2859ea836c664fb
Author: Jared Tobin <jared@jtobin.io>
Date:   Sun, 19 Apr 2026 12:27:03 +0800

lib: use shared ShortChannelId from ppad-bolt1

Replace the 3-field ShortChannelId record with the Word64 newtype
from BOLT1.Prim. Re-export the type and its accessors
(scidBlockHeight, scidTxIndex, scidOutputIndex, scidWord64).
Simplify encode/decode to use the Word64 representation directly.

Diffstat:
M
lib/Lightning/Protocol/BOLT4/Codec.hs
 | 
40
+++++++++++++---------------------------
M
lib/Lightning/Protocol/BOLT4/Types.hs
 | 
16
+++++++++-------

2 files changed, 22 insertions(+), 34 deletions(-)
diff --git a/lib/Lightning/Protocol/BOLT4/Codec.hs b/lib/Lightning/Protocol/BOLT4/Codec.hs
@@ -46,7 +46,7 @@ module Lightning.Protocol.BOLT4.Codec (
   , decodeWord32TU
   ) where
 
-import Data.Bits (shiftL, shiftR, (.&.))
+import Data.Bits (shiftL)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Builder as B
 import qualified Data.ByteString.Lazy as BL
@@ -225,39 +225,25 @@ parseHopPayload = go emptyHop
 
 -- ShortChannelId -----------------------------------------------------------
 
--- | Encode ShortChannelId to 8 bytes.
--- Format: 3 bytes block || 3 bytes tx || 2 bytes output (all BE)
+-- | Encode ShortChannelId to 8 bytes big-endian.
 encodeShortChannelId :: ShortChannelId -> BS.ByteString
-encodeShortChannelId (ShortChannelId !blk !tx !out) = toStrict $
-  -- Block height: 3 bytes
-  B.word8 (fromIntegral (blk `shiftR` 16) .&. 0xFF) <>
-  B.word8 (fromIntegral (blk `shiftR` 8) .&. 0xFF) <>
-  B.word8 (fromIntegral blk .&. 0xFF) <>
-  -- Tx index: 3 bytes
-  B.word8 (fromIntegral (tx `shiftR` 16) .&. 0xFF) <>
-  B.word8 (fromIntegral (tx `shiftR` 8) .&. 0xFF) <>
-  B.word8 (fromIntegral tx .&. 0xFF) <>
-  -- Output index: 2 bytes
-  B.word16BE out
+encodeShortChannelId !sci = toStrict (B.word64BE (scidWord64 sci))
 {-# INLINE encodeShortChannelId #-}
 
--- | Decode ShortChannelId from 8 bytes.
+-- | Decode ShortChannelId from 8 bytes big-endian.
 decodeShortChannelId :: BS.ByteString -> Maybe ShortChannelId
 decodeShortChannelId !bs
   | BS.length bs /= 8 = Nothing
   | otherwise =
-      let !b0 = fromIntegral (BS.index bs 0) :: Word32
-          !b1 = fromIntegral (BS.index bs 1) :: Word32
-          !b2 = fromIntegral (BS.index bs 2) :: Word32
-          !blk = (b0 `shiftL` 16) + (b1 `shiftL` 8) + b2
-          !t0 = fromIntegral (BS.index bs 3) :: Word32
-          !t1 = fromIntegral (BS.index bs 4) :: Word32
-          !t2 = fromIntegral (BS.index bs 5) :: Word32
-          !tx = (t0 `shiftL` 16) + (t1 `shiftL` 8) + t2
-          !o0 = fromIntegral (BS.index bs 6) :: Word16
-          !o1 = fromIntegral (BS.index bs 7) :: Word16
-          !out = (o0 `shiftL` 8) + o1
-      in  Just (ShortChannelId blk tx out)
+      let !w = (fromIntegral (BS.index bs 0) `shiftL` 56)
+            + (fromIntegral (BS.index bs 1) `shiftL` 48)
+            + (fromIntegral (BS.index bs 2) `shiftL` 40)
+            + (fromIntegral (BS.index bs 3) `shiftL` 32)
+            + (fromIntegral (BS.index bs 4) `shiftL` 24)
+            + (fromIntegral (BS.index bs 5) `shiftL` 16)
+            + (fromIntegral (BS.index bs 6) `shiftL` 8)
+            +  fromIntegral (BS.index bs 7) :: Word64
+      in  Just (ShortChannelId w)
 {-# INLINE decodeShortChannelId #-}
 
 -- Failure messages ---------------------------------------------------------
diff --git a/lib/Lightning/Protocol/BOLT4/Types.hs b/lib/Lightning/Protocol/BOLT4/Types.hs
@@ -16,6 +16,11 @@ module Lightning.Protocol.BOLT4.Types (
     OnionPacket(..)
   , HopPayload(..)
   , ShortChannelId(..)
+  , shortChannelId
+  , scidBlockHeight
+  , scidTxIndex
+  , scidOutputIndex
+  , scidWord64
   , PaymentData(..)
   , TlvRecord(..)
 
@@ -67,6 +72,10 @@ import Data.Bits ((.&.), (.|.))
 import qualified Data.ByteString as BS
 import Data.Word (Word8, Word16, Word32, Word64)
 import GHC.Generics (Generic)
+import Lightning.Protocol.BOLT1.Prim
+  ( ShortChannelId(..), shortChannelId
+  , scidBlockHeight, scidTxIndex, scidOutputIndex, scidWord64
+  )
 
 -- Packet types -------------------------------------------------------------
 
@@ -89,13 +98,6 @@ data HopPayload = HopPayload
   , hpUnknownTlvs    :: ![TlvRecord]            -- ^ Unknown types
   } deriving (Eq, Show, Generic)
 
--- | Short channel ID (8 bytes): block height, tx index, output index.
-data ShortChannelId = ShortChannelId
-  { sciBlockHeight :: {-# UNPACK #-} !Word32  -- ^ 3 bytes in encoding
-  , sciTxIndex     :: {-# UNPACK #-} !Word32  -- ^ 3 bytes in encoding
-  , sciOutputIndex :: {-# UNPACK #-} !Word16  -- ^ 2 bytes in encoding
-  } deriving (Eq, Show, Generic)
-
 -- | Payment data for final hop (TLV type 8).
 data PaymentData = PaymentData
   { pdPaymentSecret :: !BS.ByteString         -- ^ 32 bytes