Generating full xcmp proof (#132)

* comment for generating stage2

* Adding ability to grab ParaMerkleProof.. wasm trap error..

* fixing bug with paraId

* fixing proof generation

* small refactorings

* got stage4 and stage 3 proof generation setup

* adding small func and test for digest

* generating correct full proof

* final cleanup

pallets/xcmp_message_stuffer/src/lib.rs

@@ -31,19 +31,39 @@ pub trait XcmpMessageProvider<Hash> {
 	fn get_xcmp_messages(block_hash: Hash, para_id: ParaId) -> Self::XcmpMessages;
 }
 
+#[derive(Debug, PartialEq, Eq, Clone, Encode, Decode, TypeInfo)]
+pub struct ChannelMerkleProof {
+	pub root: H256,
+	pub proof: Vec<H256>,
+	pub num_leaves: u64,
+	pub leaf_index: u64,
+	pub leaf: H256,
+}
+
+impl Default for ChannelMerkleProof {
+	fn default() -> Self {
+		ChannelMerkleProof {
+			root: H256::zero(),
+			proof: Vec::new(),
+			num_leaves: 0u64,
+			leaf_index: 0u64,
+			leaf: H256::zero(),
+		}
+	}
+}
+
 type XcmpMessages<T, I> = <<T as crate::Config<I>>::XcmpDataProvider as XcmpMessageProvider<<T as frame_system::Config>::Hash>>::XcmpMessages;
 type MmrProof = Proof<H256>;
 type ChannelId = u64;
 type BinaryMerkleProof = ();
 
-
 #[derive(Debug, PartialEq, Eq, Clone, Encode, Decode, TypeInfo)]
 pub struct XcmpProof {
 	// TODO: Probably should rename each of these stages to some fancy name
 	// TODO: Remove tuples
 	pub stage_1: (MmrProof, Vec<EncodableOpaqueLeaf>),
 	pub stage_2: ParaMerkleProof,
-	pub stage_3: BinaryMerkleProof,
+	pub stage_3: ChannelMerkleProof,
 	pub stage_4: (MmrProof, Vec<EncodableOpaqueLeaf>),
 }
 
@@ -121,7 +141,6 @@ pub mod pallet {
 	#[pallet::call]
 	impl<T: Config<I>, I: 'static> Pallet<T, I> {
 
-		// TODO: This will
 		#[pallet::call_index(0)]
 		#[pallet::weight(Weight::from_parts(10_000, 0) + T::DbWeight::get().writes(1))]
 		pub fn submit_test_proof(origin: OriginFor<T>, mmr_proof: MmrProof, leaves: Vec<EncodableOpaqueLeaf>, channel_id: u64) -> DispatchResult {
@@ -216,6 +235,7 @@ pub mod pallet {
 			// Verify stage 2..
 			// grab ParaHeader root from stage_1_proof
 			// let para_header_root = Decode::decode(stage_1_leaves)
+			// Take Last leaf element as the para_header_root selected
 			// let (stage_2_proof, stage_2_leaves) = xcmp_proof.stage_2;
 
 			// These are different leaves they arent the MmrLeaves they are Binary Merkle Leaves
@@ -306,4 +326,13 @@ impl<T: Config<I>, I: 'static> LeafDataProvider for Pallet<T, I> {
 			parent_number_and_hash: ParentNumberAndHash::<T>::leaf_data(),
 		}
 	}
+}
+
+sp_api::decl_runtime_apis! {
+	/// API useful for BEEFY light clients.
+	pub trait ChannelMerkleApi
+	{
+		/// Return BinaryMerkle Proof for a particular parachains inclusion in ParaHeader tree
+		fn get_xcmp_channels_proof(channel_id: u64) -> Option<ChannelMerkleProof>;
+	}
 }

runtime/src/lib.rs

@@ -27,7 +27,9 @@ use sp_runtime::{
 
 use sp_consensus_beefy::mmr::MmrLeafVersion;
 
-use parity_scale_codec::Encode;
+use parity_scale_codec::{Encode, Decode};
+
+use polkadot_runtime_parachains::paras::{ParaMerkleProof, ParaLeaf};
 
 use sp_std::prelude::*;
 #[cfg(feature = "std")]
@@ -505,6 +507,28 @@ impl CollectXcmpChannelMmrRoots for XcmpChannelRootCollector {
 	}
 }
 
+use pallet_xcmp_message_stuffer::ChannelMerkleProof;
+pub struct ChannelMerkleProofGen;
+impl ChannelMerkleProofGen {
+	// TODO: Allow the channel_id to select the appropriate MMR and index of leaf
+	pub fn gen_merkle_proof(_channel_id: u64) -> Option<ChannelMerkleProof> {
+		let index_to_prove = 0;
+
+		let merkle_proof = binary_merkle_tree::merkle_proof::<mmr::Hashing, _, sp_core::H256>(
+			vec![MmrParaA::mmr_root_hash(), MmrParaB::mmr_root_hash()],
+			index_to_prove
+		);
+		let result_proof = ChannelMerkleProof {
+			root: merkle_proof.root,
+			proof: merkle_proof.proof,
+			num_leaves: merkle_proof.number_of_leaves as u64,
+			leaf_index: merkle_proof.leaf_index as u64,
+			leaf: merkle_proof.leaf,
+		};
+		Some(result_proof)
+	}
+}
+
 
 parameter_types! {
 	/// Version of the produced MMR leaf.
@@ -735,6 +759,12 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl pallet_xcmp_message_stuffer::ChannelMerkleApi<Block> for Runtime {
+		fn get_xcmp_channels_proof(channel_id: u64) -> Option<ChannelMerkleProof> {
+			ChannelMerkleProofGen::gen_merkle_proof(channel_id)
+		}
+	}
+
 	#[api_version(3)]
 	impl mmr::MmrApi<Block, mmr::Hash, BlockNumber> for Runtime {
 		fn mmr_root(mmr_id: u64) -> Result<mmr::Hash, mmr::Error> {

xcmp_relayer/Cargo.toml

@@ -11,6 +11,7 @@ runtime = { path = "../runtime", package = "parachain-template-runtime" }
 
 polkadot-runtime-parachains = { workspace = true }
 polkadot-parachain = { workspace = true }
+cumulus-primitives-core = { workspace = true }
 serde_json = { workspace = true }
 parity-scale-codec = { workspace = true }
 jsonrpsee = { workspace = true }
@@ -27,6 +28,7 @@ lazy_static = { workspace = true }
 sp-runtime = { workspace = true }
 sp-core = { workspace = true }
 sp-mmr-primitives = { workspace = true }
+sp-consensus-beefy = { workspace = true }
 
 subxt = { workspace = true }
 subxt-signer = { workspace = true }