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Relax witness size checking #103

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Relax witness size checking #103

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df89776
wire: remove erroneous witness size check in wire parsing
Roasbeef Oct 10, 2022
c96645c
wire: increase max witness items per input
ellemouton Nov 1, 2022
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20 changes: 11 additions & 9 deletions wire/msgtx.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,17 +96,18 @@ const (

// maxWitnessItemsPerInput is the maximum number of witness items to
// be read for the witness data for a single TxIn. This number is
// derived using a possble lower bound for the encoding of a witness
// derived using a possible lower bound for the encoding of a witness
// item: 1 byte for length + 1 byte for the witness item itself, or two
// bytes. This value is then divided by the currently allowed maximum
// "cost" for a transaction.
maxWitnessItemsPerInput = 500000
// "cost" for a transaction. We use this for an upper bound for the
// buffer and consensus makes sure that the weight of a transaction
// cannot be more than 4000000.
maxWitnessItemsPerInput = 4_000_000

// maxWitnessItemSize is the maximum allowed size for an item within
// an input's witness data. This number is derived from the fact that
// for script validation, each pushed item onto the stack must be less
// than 10k bytes.
maxWitnessItemSize = 11000
// an input's witness data. This value is bounded by the largest
// possible block size, post segwit v1 (taproot).
maxWitnessItemSize = 4_000_000
)

// TxFlagMarker is the first byte of the FLAG field in a bitcoin tx
Expand Down Expand Up @@ -588,8 +589,9 @@ func (msg *MsgTx) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) error
// item itself.
txin.Witness = make([][]byte, witCount)
for j := uint64(0); j < witCount; j++ {
txin.Witness[j], err = readScript(r, pver,
maxWitnessItemSize, "script witness item")
txin.Witness[j], err = readScript(
r, pver, maxWitnessItemSize, "script witness item",
)
if err != nil {
returnScriptBuffers()
return err
Expand Down