From 2077805384eb8f19aa96fcbd4a2beaa9f806845e Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Thu, 14 Oct 2021 21:32:40 -0700
Subject: [PATCH] fix: correctly encode multihashes with serde
The number of digest bytes written needs to match the size.
See the upstream issue here: https://github.com/multiformats/rust-multihash/pull/140
All credit goes to @koushiro. My one change is to not allocate.
---
src/multihash.rs | 40 ++++++++++++++++++++++++++++++----------
1 file changed, 30 insertions(+), 10 deletions(-)
diff --git a/src/multihash.rs b/src/multihash.rs
index 55f4fde..f8636a0 100644
--- a/src/multihash.rs
+++ b/src/multihash.rs
@@ -194,11 +194,9 @@ impl<const S: usize> parity_scale_codec::Encode for Multihash<S> {
&self,
dest: &mut EncOut,
) {
- let mut digest = [0; S];
- digest.copy_from_slice(&self.digest);
self.code.encode_to(dest);
self.size.encode_to(dest);
- digest.encode_to(dest);
+ dest.write(self.digest());
}
}
@@ -210,11 +208,17 @@ impl<const S: usize> parity_scale_codec::Decode for Multihash<S> {
fn decode<DecIn: parity_scale_codec::Input>(
input: &mut DecIn,
) -> Result<Self, parity_scale_codec::Error> {
- Ok(Multihash {
+ let mut mh = Multihash {
code: parity_scale_codec::Decode::decode(input)?,
size: parity_scale_codec::Decode::decode(input)?,
- digest: <[u8; S]>::decode(input)?,
- })
+ digest: [0; S],
+ };
+ if mh.size as usize > S {
+ Err(parity_scale_codec::Error::from("invalid size"))
+ } else {
+ input.read(&mut mh.digest[..mh.size as usize])?;
+ Ok(mh)
+ }
}
}
@@ -318,15 +322,31 @@ mod tests {
#[test]
#[cfg(feature = "scale-codec")]
fn test_scale() {
+ use crate::{Hasher, Sha2_256};
use parity_scale_codec::{
Decode,
Encode,
};
- let mh = Multihash::<32>::default();
- let bytes = mh.encode();
- let mh2: Multihash<32> = Decode::decode(&mut &bytes[..]).unwrap();
- assert_eq!(mh, mh2);
+ let mh1 = Multihash::<32>::wrap(
+ Code::Sha2_256.into(),
+ Sha2_256::digest(b"hello world").as_ref(),
+ )
+ .unwrap();
+ // println!("mh1: code = {}, size = {}, digest = {:?}", mh1.code(), mh1.size(), mh1.digest());
+ let mh1_bytes = mh1.encode();
+ // println!("Multihash<32>: {}", hex::encode(&mh1_bytes));
+ let mh2: Multihash<32> = Decode::decode(&mut &mh1_bytes[..]).unwrap();
+ assert_eq!(mh1, mh2);
+
+ let mh3: Multihash<64> = Code::Sha2_256.digest(b"hello world");
+ // println!("mh3: code = {}, size = {}, digest = {:?}", mh3.code(), mh3.size(), mh3.digest());
+ let mh3_bytes = mh3.encode();
+ // println!("Multihash<64>: {}", hex::encode(&mh3_bytes));
+ let mh4: Multihash<64> = Decode::decode(&mut &mh3_bytes[..]).unwrap();
+ assert_eq!(mh3, mh4);
+
+ assert_eq!(mh1_bytes, mh3_bytes);
}
#[test]