use gossip message directly

cumulus/network/src/lib.rs

@@ -22,31 +22,16 @@ use substrate_client::error::{Error as ClientError};
 use sr_primitives::traits::{Block as BlockT};
 use substrate_consensus_common::block_validation::{Validation, BlockAnnounceValidator};
 
-use polkadot_primitives::{
-	Hash as PHash, parachain::{CandidateReceipt, ValidatorIndex, ValidatorSignature, ValidatorId},
-};
-use polkadot_statement_table::Statement;
+use polkadot_primitives::parachain::ValidatorId;
+use polkadot_statement_table::{SignedStatement, Statement};
 use polkadot_validation::check_statement;
+use polkadot_network::gossip::{GossipStatement, GossipMessage};
 
 use codec::{Decode, Encode};
 
 use std::marker::PhantomData;
 
-/// Justification that a parachain block is the parachain block candidate of one of the relay chain
-/// validator.
-#[derive(Encode, Decode)]
-pub struct BlockCandidateJustification {
-	/// Receipt of the parachain block candidate of the signer.
-	candidate_receipt: CandidateReceipt,
-	/// Signer of `signature`.
-	signer: ValidatorIndex,
-	/// Signature of the Candidate statement with `candidate_receipt`.
-	signature: ValidatorSignature,
-	/// The parent block of which the candidate must be include.
-	relay_chain_parent_hash: PHash,
-}
-
-/// Validate that data is a valid justification form a relay-chain validator that the block is a
+/// Validate that data is a valid justification from a relay-chain validator that the block is a
 /// valid parachain-block candidate.
 pub struct JustifiedBlockAnnounceValidator<B> {
 	authorities: Vec<ValidatorId>,
@@ -66,34 +51,59 @@ impl<B: BlockT> BlockAnnounceValidator<B> for JustifiedBlockAnnounceValidator<B>
 	fn validate(&mut self, header: &B::Header, mut data: &[u8])
 		-> Result<Validation, Box<dyn std::error::Error + Send>>
 	{
-		let justification = BlockCandidateJustification::decode(&mut data)
+		// Check data is a gossip message.
+		let gossip_message = GossipMessage::decode(&mut data)
 			.map_err(|_| Box::new(ClientError::BadJustification(
-				"cannot decode block candidate justification".to_string()
+				"cannot decode block announced justification, must be a gossip message".to_string()
 			)) as Box<_>)?;
 
-		// Check the header in the candidate_receipt match header given header.
-		if header.encode() != justification.candidate_receipt.head_data.0 {
+		// Check message is a gossip statement.
+		let gossip_statement = match gossip_message {
+			GossipMessage::Statement(gossip_statement) => gossip_statement,
+			_ => return Err(Box::new(ClientError::BadJustification(
+				"block announced justification statement must be a gossip statement".to_string()
+			)) as Box<_>)
+		};
+
+		let GossipStatement {
+				relay_chain_leaf,
+				signed_statement: SignedStatement {
+					statement,
+					signature,
+					sender,
+				}
+		} = gossip_statement;
+
+		// Check that the signer is a legit validator.
+		let signer = self.authorities.get(sender as usize)
+			.ok_or_else(|| Box::new(ClientError::BadJustification(
+				"block accounced justification signer is a validator index out of bound".to_string()
+			)) as Box<_>)?;
+
+		// Check statement is correctly signed.
+		if !check_statement(
+			&statement,
+			&signature,
+			signer.clone(),
+			&relay_chain_leaf,
+		) {
 			return Err(Box::new(ClientError::BadJustification(
-				"block candidate header does not match its justification".to_string()
+				"block announced justification signature is invalid".to_string()
 			)) as Box<_>)
 		}
 
-		// Check that the signer is a legit validator.
-		let signer = self.authorities.get(justification.signer as usize)
-			.ok_or_else(|| Box::new(ClientError::BadJustification(
-				"block candidate justification signer is a validator index out of bound".to_string()
-			)) as Box<_>)?;
+		// Check statement is a candidate statement.
+		let candidate_receipt = match statement {
+			Statement::Candidate(candidate_receipt) => candidate_receipt,
+			_ => return Err(Box::new(ClientError::BadJustification(
+				"block announced justification statement must be a candidate statement".to_string()
+			)) as Box<_>)
+		};
 
-		// Check statement is signed.
-		let statement = Statement::Candidate(justification.candidate_receipt);
-		if !check_statement(
-			&statement,
-			&justification.signature,
-			signer.clone(),
-			&justification.relay_chain_parent_hash
-		) {
+		// Check the header in the candidate_receipt match header given header.
+		if header.encode() != candidate_receipt.head_data.0 {
 			return Err(Box::new(ClientError::BadJustification(
-				"block candidate justification signature is invalid".to_string()
+				"block announced header does not match the one justified".to_string()
 			)) as Box<_>)
 		}