Refactor epoch changes to a separate crate (#4785)

* Init epoch changes module * Initial integration of new epoch changes module for BABE * Fix all initial compile errors * rename: digest -> digests * Fix babe tests * Bump impl_version * Fix more test issues * Remove test flag for tree It unfortunately won't work for multiple crates. * Update cargo lock * Fix duplicate parking_lot version * Add missing license header
2026-06-13 12:51:05 +00:00 · 2020-02-06 16:48:38 +01:00
parent c7a7197f97
commit 4df27e760e
15 changed files with 265 additions and 218 deletions
@@ -0,0 +1,281 @@
+// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Private implementation details of BABE digests.
+
+#[cfg(feature = "std")]
+use super::{BABE_ENGINE_ID, AuthoritySignature};
+#[cfg(not(feature = "std"))]
+use super::{VRF_OUTPUT_LENGTH, VRF_PROOF_LENGTH};
+use super::{AuthorityId, AuthorityIndex, SlotNumber, BabeAuthorityWeight};
+#[cfg(feature = "std")]
+use sp_runtime::{DigestItem, generic::OpaqueDigestItemId};
+#[cfg(feature = "std")]
+use std::fmt::Debug;
+use codec::{Decode, Encode};
+#[cfg(feature = "std")]
+use codec::{Codec, Input, Error};
+#[cfg(feature = "std")]
+use schnorrkel::{
+	SignatureError, errors::MultiSignatureStage,
+	vrf::{VRFProof, VRFOutput, VRF_OUTPUT_LENGTH, VRF_PROOF_LENGTH}
+};
+use sp_std::vec::Vec;
+
+
+/// A BABE pre-runtime digest. This contains all data required to validate a
+/// block and for the BABE runtime module. Slots can be assigned to a primary
+/// (VRF based) and to a secondary (slot number based).
+#[cfg(feature = "std")]
+#[derive(Clone, Debug)]
+pub enum PreDigest {
+	/// A primary VRF-based slot assignment.
+	Primary {
+		/// VRF output
+		vrf_output: VRFOutput,
+		/// VRF proof
+		vrf_proof: VRFProof,
+		/// Authority index
+		authority_index: super::AuthorityIndex,
+		/// Slot number
+		slot_number: SlotNumber,
+	},
+	/// A secondary deterministic slot assignment.
+	Secondary {
+		/// Authority index
+		authority_index: super::AuthorityIndex,
+		/// Slot number
+		slot_number: SlotNumber,
+	},
+}
+
+#[cfg(feature = "std")]
+impl PreDigest {
+	/// Returns the slot number of the pre digest.
+	pub fn authority_index(&self) -> AuthorityIndex {
+		match self {
+			PreDigest::Primary { authority_index, .. } => *authority_index,
+			PreDigest::Secondary { authority_index, .. } => *authority_index,
+		}
+	}
+
+	/// Returns the slot number of the pre digest.
+	pub fn slot_number(&self) -> SlotNumber {
+		match self {
+			PreDigest::Primary { slot_number, .. } => *slot_number,
+			PreDigest::Secondary { slot_number, .. } => *slot_number,
+		}
+	}
+
+	/// Returns the weight _added_ by this digest, not the cumulative weight
+	/// of the chain.
+	pub fn added_weight(&self) -> crate::BabeBlockWeight {
+		match self {
+			PreDigest::Primary { .. } => 1,
+			PreDigest::Secondary { .. } => 0,
+		}
+	}
+}
+
+/// A raw version of `BabePreDigest`, usable on `no_std`.
+#[derive(Copy, Clone, Encode, Decode)]
+pub enum RawPreDigest {
+	/// A primary VRF-based slot assignment.
+	#[codec(index = "1")]
+	Primary {
+		/// Authority index
+		authority_index: AuthorityIndex,
+		/// Slot number
+		slot_number: SlotNumber,
+		/// VRF output
+		vrf_output: [u8; VRF_OUTPUT_LENGTH],
+		/// VRF proof
+		vrf_proof: [u8; VRF_PROOF_LENGTH],
+	},
+	/// A secondary deterministic slot assignment.
+	#[codec(index = "2")]
+	Secondary {
+		/// Authority index
+		///
+		/// This is not strictly-speaking necessary, since the secondary slots
+		/// are assigned based on slot number and epoch randomness. But including
+		/// it makes things easier for higher-level users of the chain data to
+		/// be aware of the author of a secondary-slot block.
+		authority_index: AuthorityIndex,
+		/// Slot number
+		slot_number: SlotNumber,
+	},
+}
+
+impl RawPreDigest {
+	/// Returns the slot number of the pre digest.
+	pub fn slot_number(&self) -> SlotNumber {
+		match self {
+			RawPreDigest::Primary { slot_number, .. } => *slot_number,
+			RawPreDigest::Secondary { slot_number, .. } => *slot_number,
+		}
+	}
+}
+
+#[cfg(feature = "std")]
+impl Encode for PreDigest {
+	fn encode(&self) -> Vec<u8> {
+		let raw = match self {
+			PreDigest::Primary {
+				vrf_output,
+				vrf_proof,
+				authority_index,
+				slot_number,
+			} => {
+				RawPreDigest::Primary {
+					vrf_output: *vrf_output.as_bytes(),
+					vrf_proof: vrf_proof.to_bytes(),
+					authority_index: *authority_index,
+					slot_number: *slot_number,
+				}
+			},
+			PreDigest::Secondary {
+				authority_index,
+				slot_number,
+			} => {
+				RawPreDigest::Secondary {
+					authority_index: *authority_index,
+					slot_number: *slot_number,
+				}
+			},
+		};
+
+		codec::Encode::encode(&raw)
+	}
+}
+
+#[cfg(feature = "std")]
+impl codec::EncodeLike for PreDigest {}
+
+#[cfg(feature = "std")]
+impl Decode for PreDigest {
+	fn decode<R: Input>(i: &mut R) -> Result<Self, Error> {
+		let pre_digest = match Decode::decode(i)? {
+			RawPreDigest::Primary { vrf_output, vrf_proof, authority_index, slot_number } => {
+				// Verify (at compile time) that the sizes in babe_primitives are correct
+				let _: [u8; super::VRF_OUTPUT_LENGTH] = vrf_output;
+				let _: [u8; super::VRF_PROOF_LENGTH] = vrf_proof;
+
+				PreDigest::Primary {
+					vrf_proof: VRFProof::from_bytes(&vrf_proof).map_err(convert_error)?,
+					vrf_output: VRFOutput::from_bytes(&vrf_output).map_err(convert_error)?,
+					authority_index,
+					slot_number,
+				}
+			},
+			RawPreDigest::Secondary { authority_index, slot_number } => {
+				PreDigest::Secondary { authority_index, slot_number }
+			},
+		};
+
+		Ok(pre_digest)
+	}
+}
+
+/// Information about the next epoch. This is broadcast in the first block
+/// of the epoch.
+#[derive(Decode, Encode, Default, PartialEq, Eq, Clone, sp_runtime::RuntimeDebug)]
+pub struct NextEpochDescriptor {
+	/// The authorities.
+	pub authorities: Vec<(AuthorityId, BabeAuthorityWeight)>,
+
+	/// The value of randomness to use for the slot-assignment.
+	pub randomness: [u8; VRF_OUTPUT_LENGTH],
+}
+
+/// A digest item which is usable with BABE consensus.
+#[cfg(feature = "std")]
+pub trait CompatibleDigestItem: Sized {
+	/// Construct a digest item which contains a BABE pre-digest.
+	fn babe_pre_digest(seal: PreDigest) -> Self;
+
+	/// If this item is an BABE pre-digest, return it.
+	fn as_babe_pre_digest(&self) -> Option<PreDigest>;
+
+	/// Construct a digest item which contains a BABE seal.
+	fn babe_seal(signature: AuthoritySignature) -> Self;
+
+	/// If this item is a BABE signature, return the signature.
+	fn as_babe_seal(&self) -> Option<AuthoritySignature>;
+
+	/// If this item is a BABE epoch, return it.
+	fn as_next_epoch_descriptor(&self) -> Option<NextEpochDescriptor>;
+}
+
+#[cfg(feature = "std")]
+impl<Hash> CompatibleDigestItem for DigestItem<Hash> where
+	Hash: Debug + Send + Sync + Eq + Clone + Codec + 'static
+{
+	fn babe_pre_digest(digest: PreDigest) -> Self {
+		DigestItem::PreRuntime(BABE_ENGINE_ID, digest.encode())
+	}
+
+	fn as_babe_pre_digest(&self) -> Option<PreDigest> {
+		self.try_to(OpaqueDigestItemId::PreRuntime(&BABE_ENGINE_ID))
+	}
+
+	fn babe_seal(signature: AuthoritySignature) -> Self {
+		DigestItem::Seal(BABE_ENGINE_ID, signature.encode())
+	}
+
+	fn as_babe_seal(&self) -> Option<AuthoritySignature> {
+		self.try_to(OpaqueDigestItemId::Seal(&BABE_ENGINE_ID))
+	}
+
+	fn as_next_epoch_descriptor(&self) -> Option<NextEpochDescriptor> {
+		self.try_to(OpaqueDigestItemId::Consensus(&BABE_ENGINE_ID))
+			.and_then(|x: super::ConsensusLog| match x {
+				super::ConsensusLog::NextEpochData(n) => Some(n),
+				_ => None,
+			})
+	}
+}
+
+#[cfg(feature = "std")]
+fn convert_error(e: SignatureError) -> codec::Error {
+	use SignatureError::*;
+	use MultiSignatureStage::*;
+	match e {
+		EquationFalse => "Signature error: `EquationFalse`".into(),
+		PointDecompressionError => "Signature error: `PointDecompressionError`".into(),
+		ScalarFormatError => "Signature error: `ScalarFormatError`".into(),
+		NotMarkedSchnorrkel => "Signature error: `NotMarkedSchnorrkel`".into(),
+		BytesLengthError { .. } => "Signature error: `BytesLengthError`".into(),
+		MuSigAbsent { musig_stage: Commitment } =>
+			"Signature error: `MuSigAbsent` at stage `Commitment`".into(),
+		MuSigAbsent { musig_stage: Reveal } =>
+			"Signature error: `MuSigAbsent` at stage `Reveal`".into(),
+		MuSigAbsent { musig_stage: Cosignature } =>
+			"Signature error: `MuSigAbsent` at stage `Commitment`".into(),
+		MuSigInconsistent { musig_stage: Commitment, duplicate: true } =>
+			"Signature error: `MuSigInconsistent` at stage `Commitment` on duplicate".into(),
+		MuSigInconsistent { musig_stage: Commitment, duplicate: false } =>
+			"Signature error: `MuSigInconsistent` at stage `Commitment` on not duplicate".into(),
+		MuSigInconsistent { musig_stage: Reveal, duplicate: true } =>
+			"Signature error: `MuSigInconsistent` at stage `Reveal` on duplicate".into(),
+		MuSigInconsistent { musig_stage: Reveal, duplicate: false } =>
+			"Signature error: `MuSigInconsistent` at stage `Reveal` on not duplicate".into(),
+		MuSigInconsistent { musig_stage: Cosignature, duplicate: true } =>
+			"Signature error: `MuSigInconsistent` at stage `Cosignature` on duplicate".into(),
+		MuSigInconsistent { musig_stage: Cosignature, duplicate: false } =>
+			"Signature error: `MuSigInconsistent` at stage `Cosignature` on not duplicate".into(),
+	}
+}