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Refactor witness_version and is_witness_program 

These two functions are related. We cannot, by definition, get the
witness version from a script that is not a witness program but
currently the code is not linking these two things.

Refactor by doing:

- Move the check of the witness program bip rules to `witness_version`
- Call `witness_version().is_some()` in the predicate

Improve the docs while we are at it to include the bip text in the
rustdoc. Note I didn't bother referencing the segwit bip number, this
bip text is pretty well known.
This commit is contained in:
Tobin C. Harding 2024-03-22 07:07:07 +11:00
parent dac552b436
commit dec05b63e9
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GPG Key ID: 40BF9E4C269D6607
1 changed files with 28 additions and 18 deletions
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46
bitcoin/src/blockdata/script/borrowed.rs
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@ -165,9 +165,35 @@ impl Script {
}
/// Returns witness version of the script, if any, assuming the script is a `scriptPubkey`.
///
/// # Returns
///
/// The witness version if this script is found to conform to the SegWit rules:
///
/// > A scriptPubKey (or redeemScript as defined in BIP16/P2SH) that consists of a 1-byte
/// > push opcode (for 0 to 16) followed by a data push between 2 and 40 bytes gets a new
/// > special meaning. The value of the first push is called the "version byte". The following
/// > byte vector pushed is called the "witness program".
#[inline]
pub fn witness_version(&self) -> Option<WitnessVersion> {
self.0.first().and_then(|opcode| WitnessVersion::try_from(Opcode::from(*opcode)).ok())
let script_len = self.0.len();
if !(4..=42).contains(&script_len) {
return None;
}
let ver_opcode = Opcode::from(self.0[0]); // Version 0 or PUSHNUM_1-PUSHNUM_16
let push_opbyte = self.0[1]; // Second byte push opcode 2-40 bytes
if push_opbyte < OP_PUSHBYTES_2.to_u8() || push_opbyte > OP_PUSHBYTES_40.to_u8()
{
return None;
}
// Check that the rest of the script has the correct size
if script_len - 2 != push_opbyte as usize {
return None;
}
WitnessVersion::try_from(ver_opcode).ok()
}
/// Checks whether a script pubkey is a P2SH output.
@ -293,23 +319,7 @@ impl Script {
/// Checks whether a script pubkey is a Segregated Witness (segwit) program.
#[inline]
pub fn is_witness_program(&self) -> bool {
// A scriptPubKey (or redeemScript as defined in BIP16/P2SH) that consists of a 1-byte
// push opcode (for 0 to 16) followed by a data push between 2 and 40 bytes gets a new
// special meaning. The value of the first push is called the "version byte". The following
// byte vector pushed is called the "witness program".
let script_len = self.0.len();
if !(4..=42).contains(&script_len) {
return false;
}
let ver_opcode = Opcode::from(self.0[0]); // Version 0 or PUSHNUM_1-PUSHNUM_16
let push_opbyte = self.0[1]; // Second byte push opcode 2-40 bytes
WitnessVersion::try_from(ver_opcode).is_ok()
&& push_opbyte >= OP_PUSHBYTES_2.to_u8()
&& push_opbyte <= OP_PUSHBYTES_40.to_u8()
// Check that the rest of the script has the correct size
&& script_len - 2 == push_opbyte as usize
}
pub fn is_witness_program(&self) -> bool { self.witness_version().is_some() }
/// Checks whether a script pubkey is a P2WSH output.
#[inline]