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rust-bitcoin-unsafe-fast
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Use `PushDataLenLen` to improve confidence 

Script parsing is composed of several functions which implicitly rely on
various properties. Adding a type that restricts the valid values makes
local review easier.
This commit is contained in:
Martin Habovstiak 2023-02-18 12:18:26 +01:00
parent bb2c7ec790
commit 26fc4152ec
1 changed files with 14 additions and 5 deletions
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19
bitcoin/src/blockdata/script/instruction.rs
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@ -78,8 +78,8 @@ impl<'a> Instructions<'a> {
}
}
pub(super) fn next_push_data_len(&mut self, len: usize, min_push_len: usize) -> Option<Result<Instruction<'a>, Error>> {
let n = match read_uint_iter(&mut self.data, len) {
pub(super) fn next_push_data_len(&mut self, len: PushDataLenLen, min_push_len: usize) -> Option<Result<Instruction<'a>, Error>> {
let n = match read_uint_iter(&mut self.data, len as usize) {
Ok(n) => n,
// We do exhaustive matching to not forget to handle new variants if we extend
// `UintError` type.
@ -98,6 +98,15 @@ impl<'a> Instructions<'a> {
}
}
/// Allowed length of push data length.
///
/// This makes it easier to prove correctness of `next_push_data_len`.
pub(super) enum PushDataLenLen {
One = 1,
Two = 2,
Four = 4,
}
impl<'a> Iterator for Instructions<'a> {
type Item = Result<Instruction<'a>, Error>;
@ -130,13 +139,13 @@ impl<'a> Iterator for Instructions<'a> {
}
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA1) => {
self.next_push_data_len(1, 76)
self.next_push_data_len(PushDataLenLen::One, 76)
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA2) => {
self.next_push_data_len(2, 0x100)
self.next_push_data_len(PushDataLenLen::Two, 0x100)
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA4) => {
self.next_push_data_len(4, 0x10000)
self.next_push_data_len(PushDataLenLen::Four, 0x10000)
}
// Everything else we can push right through
_ => {