Add thin binary merkle tree wrapper implementing Codec (#1581)

* add our own version of binary-merkle-tree

* update Cargo.lock

* update version and add licence header

Author: clangenb

Cargo.lock

@@ -3178,6 +3178,15 @@ dependencies = [
  "yasna 0.3.1",
 ]
 
+[[package]]
+name = "itp-binary-merkle-tree"
+version = "0.8.0"
+dependencies = [
+ "binary-merkle-tree",
+ "parity-scale-codec",
+ "serde 1.0.193",
+]
+
 [[package]]
 name = "itp-component-container"
 version = "0.8.0"

Cargo.toml

@@ -18,6 +18,7 @@ members = [
     "core/rpc-server",
     "core/tls-websocket-server",
     "core-primitives/attestation-handler",
+    "core-primitives/binary-merkle-tree",
     "core-primitives/import-queue",
     "core-primitives/component-container",
     "core-primitives/enclave-api",

core-primitives/binary-merkle-tree/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "itp-binary-merkle-tree"
+version = "0.8.0"
+edition = "2021"
+
+[dependencies]
+parity-scale-codec = { version = "3.0.0", default-features = false, features = ["derive"], package = "parity-scale-codec" }
+serde = { version = "1.0", default-features = false, features = ["derive", "alloc"] }
+
+binary-merkle-tree = { default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.42" }
+
+[features]
+std = [
+    "parity-scale-codec/std",
+    "serde/std",
+    "binary-merkle-tree/std",
+]

core-primitives/binary-merkle-tree/src/lib.rs

@@ -0,0 +1,67 @@
+/*
+	Copyright 2021 Integritee AG and Supercomputing Systems AG
+	Copyright (C) 2017-2019 Baidu, Inc. All Rights Reserved.
+
+	Licensed under the Apache License, Version 2.0 (the "License");
+	you may not use this file except in compliance with the License.
+	You may obtain a copy of the License at
+
+		http://www.apache.org/licenses/LICENSE-2.0
+
+	Unless required by applicable law or agreed to in writing, software
+	distributed under the License is distributed on an "AS IS" BASIS,
+	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+	See the License for the specific language governing permissions and
+	limitations under the License.
+
+*/
+
+// Todo: I think we can upstream the codec change, then we can delete this crate.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(not(feature = "std"))]
+extern crate alloc;
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
+
+use parity_scale_codec::{Decode, Encode};
+use serde::{Deserialize, Serialize};
+
+// re-export the original one implementing all the merkle/logic.
+pub use binary_merkle_tree::{merkle_proof, merkle_root, verify_proof, MerkleProof};
+
+/// Custom Merkle proof that implements codec
+/// The difference to the original one is that implements the scale-codec and that the fields contain u32 instead of usize.
+#[derive(Debug, PartialEq, Eq, Decode, Encode, Deserialize, Serialize)]
+pub struct MerkleProofWithCodec<H, L> {
+	/// Root hash of generated merkle tree.
+	pub root: H,
+	/// Proof items (does not contain the leaf hash, nor the root obviously).
+	///
+	/// This vec contains all inner node hashes necessary to reconstruct the root hash given the
+	/// leaf hash.
+	pub proof: Vec<H>,
+	/// Number of leaves in the original tree.
+	///
+	/// This is needed to detect a case where we have an odd number of leaves that "get promoted"
+	/// to upper layers.
+	pub number_of_leaves: u64,
+	/// Index of the leaf the proof is for (0-based).
+	pub leaf_index: u64,
+	/// Leaf content.
+	pub leaf: L,
+}
+
+impl<H, L> From<MerkleProof<H, L>> for MerkleProofWithCodec<H, L> {
+	fn from(source: MerkleProof<H, L>) -> Self {
+		Self {
+			root: source.root,
+			proof: source.proof,
+			// usize as u64 can't panic
+			number_of_leaves: source.number_of_leaves as u64,
+			leaf_index: source.leaf_index as u64,
+			leaf: source.leaf,
+		}
+	}
+}