Custom justification verification (#979)

* custom justification verification * is_ancestor -> ensure_descendant * PrecommitIsNotCommitDescendant * Update primitives/header-chain/src/justification.rs Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com> Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>
2026-04-26 02:57:57 +00:00 · 2021-05-31 21:58:45 +03:00
parent 6301ae0636
commit 700d63672b
5 changed files with 484 additions and 127 deletions
@@ -0,0 +1,317 @@
+// Copyright 2020-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Tests inside this module are made to ensure that our custom justification verification
+//! implementation works exactly as `fn finality_grandpa::validate_commit`.
+//!
+//! Some of tests in this module may partially duplicate tests from `justification.rs`,
+//! but their purpose is different.
+
+use assert_matches::assert_matches;
+use bp_header_chain::justification::{verify_justification, Error, GrandpaJustification};
+use bp_test_utils::{
+	header_id, make_justification_for_header, signed_precommit, test_header, Account, JustificationGeneratorParams,
+	ALICE, BOB, CHARLIE, DAVE, EVE, TEST_GRANDPA_SET_ID,
+};
+use finality_grandpa::voter_set::VoterSet;
+use sp_finality_grandpa::{AuthorityId, AuthorityWeight};
+use sp_runtime::traits::Header as HeaderT;
+
+type TestHeader = sp_runtime::testing::Header;
+type TestHash = <TestHeader as HeaderT>::Hash;
+type TestNumber = <TestHeader as HeaderT>::Number;
+
+/// Implementation of `finality_grandpa::Chain` that is used in tests.
+struct AncestryChain(bp_header_chain::justification::AncestryChain<TestHeader>);
+
+impl AncestryChain {
+	fn new(ancestry: &[TestHeader]) -> Self {
+		Self(bp_header_chain::justification::AncestryChain::new(ancestry))
+	}
+}
+
+impl finality_grandpa::Chain<TestHash, TestNumber> for AncestryChain {
+	fn ancestry(&self, base: TestHash, block: TestHash) -> Result<Vec<TestHash>, finality_grandpa::Error> {
+		let mut route = Vec::new();
+		let mut current_hash = block;
+		loop {
+			if current_hash == base {
+				break;
+			}
+			match self.0.parents.get(&current_hash).cloned() {
+				Some(parent_hash) => {
+					current_hash = parent_hash;
+					route.push(current_hash);
+				}
+				_ => return Err(finality_grandpa::Error::NotDescendent),
+			}
+		}
+		route.pop(); // remove the base
+
+		Ok(route)
+	}
+}
+
+/// Get a full set of accounts.
+fn full_accounts_set() -> Vec<(Account, AuthorityWeight)> {
+	vec![(ALICE, 1), (BOB, 1), (CHARLIE, 1), (DAVE, 1), (EVE, 1)]
+}
+
+/// Get a full set of GRANDPA authorities.
+fn full_voter_set() -> VoterSet<AuthorityId> {
+	VoterSet::new(full_accounts_set().iter().map(|(id, w)| (AuthorityId::from(*id), *w))).unwrap()
+}
+
+/// Get a minimal set of accounts.
+fn minimal_accounts_set() -> Vec<(Account, AuthorityWeight)> {
+	// there are 5 accounts in the full set => we need 2/3 + 1 accounts, which results in 4 accounts
+	vec![(ALICE, 1), (BOB, 1), (CHARLIE, 1), (DAVE, 1)]
+}
+
+/// Get a minimal subset of GRANDPA authorities that have enough cumulative vote weight to justify a header finality.
+pub fn minimal_voter_set() -> VoterSet<AuthorityId> {
+	VoterSet::new(
+		minimal_accounts_set()
+			.iter()
+			.map(|(id, w)| (AuthorityId::from(*id), *w)),
+	)
+	.unwrap()
+}
+
+/// Make a valid GRANDPA justification with sensible defaults.
+pub fn make_default_justification(header: &TestHeader) -> GrandpaJustification<TestHeader> {
+	make_justification_for_header(JustificationGeneratorParams {
+		header: header.clone(),
+		authorities: minimal_accounts_set(),
+		..Default::default()
+	})
+}
+
+// the `finality_grandpa::validate_commit` function has two ways to report an unsuccessful
+// commit validation:
+//
+// 1) to return `Err()` (which only may happen if `finality_grandpa::Chain` implementation
+//    returns an error);
+// 2) to return `Ok(validation_result) if validation_result.ghost().is_none()`.
+//
+// Our implementation would just return error in both cases.
+
+#[test]
+fn same_result_when_precommit_target_has_lower_number_than_commit_target() {
+	let mut justification = make_default_justification(&test_header(1));
+	// the number of header in precommit (0) is lower than number of header in commit (1)
+	justification.commit.precommits[0].precommit.target_number = 0;
+
+	// our implementation returns an error
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Err(Error::PrecommitIsNotCommitDescendant),
+	);
+	// original implementation returns empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(None)
+	);
+}
+
+#[test]
+fn same_result_when_precommit_target_is_not_descendant_of_commit_target() {
+	let not_descendant = test_header::<TestHeader>(10);
+	let mut justification = make_default_justification(&test_header(1));
+	// the route from header of commit (1) to header of precommit (10) is missing from
+	// the votes ancestries
+	justification.commit.precommits[0].precommit.target_number = *not_descendant.number();
+	justification.commit.precommits[0].precommit.target_hash = not_descendant.hash();
+	justification.votes_ancestries.push(not_descendant);
+
+	// our implementation returns an error
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Err(Error::PrecommitIsNotCommitDescendant),
+	);
+	// original implementation returns empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(None)
+	);
+}
+
+#[test]
+fn same_result_when_justification_contains_duplicate_vote() {
+	let mut justification = make_default_justification(&test_header(1));
+	// the justification may contain exactly the same vote (i.e. same precommit and same signature)
+	// multiple times && it isn't treated as an error by original implementation
+	justification
+		.commit
+		.precommits
+		.push(justification.commit.precommits[0].clone());
+	justification
+		.commit
+		.precommits
+		.push(justification.commit.precommits[0].clone());
+
+	// our implementation succeeds
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Ok(()),
+	);
+	// original implementation returns non-empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(Some(_))
+	);
+}
+
+#[test]
+fn same_result_when_authority_equivocates_once_in_a_round() {
+	let mut justification = make_default_justification(&test_header(1));
+	// the justification original implementation allows authority to submit two different
+	// votes in a single round, of which only first is 'accepted'
+	justification.commit.precommits.push(signed_precommit::<TestHeader>(
+		&ALICE,
+		header_id::<TestHeader>(1),
+		justification.round,
+		TEST_GRANDPA_SET_ID,
+	));
+
+	// our implementation succeeds
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Ok(()),
+	);
+	// original implementation returns non-empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(Some(_))
+	);
+}
+
+#[test]
+fn same_result_when_authority_equivocates_twice_in_a_round() {
+	let mut justification = make_default_justification(&test_header(1));
+	// there's some code in the original implementation that should return an error when
+	// same authority submits more than two different votes in a single round:
+	// https://github.com/paritytech/finality-grandpa/blob/6aeea2d1159d0f418f0b86e70739f2130629ca09/src/lib.rs#L473
+	// but there's also a code that prevents this from happening:
+	// https://github.com/paritytech/finality-grandpa/blob/6aeea2d1159d0f418f0b86e70739f2130629ca09/src/round.rs#L287
+	// => so now we are also just ignoring all votes from the same authority, except the first one
+	justification.commit.precommits.push(signed_precommit::<TestHeader>(
+		&ALICE,
+		header_id::<TestHeader>(1),
+		justification.round,
+		TEST_GRANDPA_SET_ID,
+	));
+	justification.commit.precommits.push(signed_precommit::<TestHeader>(
+		&ALICE,
+		header_id::<TestHeader>(1),
+		justification.round,
+		TEST_GRANDPA_SET_ID,
+	));
+
+	// our implementation succeeds
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Ok(()),
+	);
+	// original implementation returns non-empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(Some(_))
+	);
+}
+
+#[test]
+fn same_result_when_there_are_not_enough_cumulative_weight_to_finalize_commit_target() {
+	// just remove one authority from the minimal set and we shall not reach the threshold
+	let mut authorities_set = minimal_accounts_set();
+	authorities_set.pop();
+	let justification = make_justification_for_header(JustificationGeneratorParams {
+		header: test_header(1),
+		authorities: authorities_set,
+		..Default::default()
+	});
+
+	// our implementation returns an error
+	assert_eq!(
+		verify_justification::<TestHeader>(
+			header_id::<TestHeader>(1),
+			TEST_GRANDPA_SET_ID,
+			&full_voter_set(),
+			&justification,
+		),
+		Err(Error::TooLowCumulativeWeight),
+	);
+	// original implementation returns empty GHOST
+	assert_matches!(
+		finality_grandpa::validate_commit(
+			&justification.commit,
+			&full_voter_set(),
+			&AncestryChain::new(&justification.votes_ancestries),
+		)
+		.map(|result| result.ghost().cloned()),
+		Ok(None)
+	);
+}