Function sp_state_machine::create_proof_check_backend

pub fn create_proof_check_backend<H>(
    root: H::Out,
    proof: StorageProof
) -> Result<TrieBackend<MemoryDB<H>, H>, Box<dyn Error>>where
    H: Hasher,
    H::Out: Codec,

Create a backend used for checking the proof, using H as hasher.

proof and root must match, i.e. root must be the correct root of proof nodes.

Examples found in repository

src/lib.rs (line 604)

	pub fn execution_proof_check<H, Exec, Spawn>(
		root: H::Out,
		proof: StorageProof,
		overlay: &mut OverlayedChanges,
		exec: &Exec,
		spawn_handle: Spawn,
		method: &str,
		call_data: &[u8],
		runtime_code: &RuntimeCode,
	) -> Result<Vec<u8>, Box<dyn Error>>
	where
		H: Hasher + 'static,
		Exec: CodeExecutor + Clone + 'static,
		H::Out: Ord + 'static + codec::Codec,
		Spawn: SpawnNamed + Send + 'static,
	{
		let trie_backend = create_proof_check_backend::<H>(root, proof)?;
		execution_proof_check_on_trie_backend::<_, _, _>(
			&trie_backend,
			overlay,
			exec,
			spawn_handle,
			method,
			call_data,
			runtime_code,
		)
	}

	/// Check execution proof on proving backend, generated by `prove_execution` call.
	pub fn execution_proof_check_on_trie_backend<H, Exec, Spawn>(
		trie_backend: &TrieBackend<MemoryDB<H>, H>,
		overlay: &mut OverlayedChanges,
		exec: &Exec,
		spawn_handle: Spawn,
		method: &str,
		call_data: &[u8],
		runtime_code: &RuntimeCode,
	) -> Result<Vec<u8>, Box<dyn Error>>
	where
		H: Hasher,
		H::Out: Ord + 'static + codec::Codec,
		Exec: CodeExecutor + Clone + 'static,
		Spawn: SpawnNamed + Send + 'static,
	{
		StateMachine::<_, H, Exec>::new(
			trie_backend,
			overlay,
			exec,
			method,
			call_data,
			Extensions::default(),
			runtime_code,
			spawn_handle,
		)
		.execute_using_consensus_failure_handler(always_untrusted_wasm())
	}

	/// Generate storage read proof.
	pub fn prove_read<B, H, I>(backend: B, keys: I) -> Result<StorageProof, Box<dyn Error>>
	where
		B: AsTrieBackend<H>,
		H: Hasher,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let trie_backend = backend.as_trie_backend();
		prove_read_on_trie_backend(trie_backend, keys)
	}

	/// State machine only allows a single level
	/// of child trie.
	pub const MAX_NESTED_TRIE_DEPTH: usize = 2;

	/// Multiple key value state.
	/// States are ordered by root storage key.
	#[derive(PartialEq, Eq, Clone)]
	pub struct KeyValueStates(pub Vec<KeyValueStorageLevel>);

	/// A key value state at any storage level.
	#[derive(PartialEq, Eq, Clone)]
	pub struct KeyValueStorageLevel {
		/// State root of the level, for
		/// top trie it is as an empty byte array.
		pub state_root: Vec<u8>,
		/// Storage of parents, empty for top root or
		/// when exporting (building proof).
		pub parent_storage_keys: Vec<Vec<u8>>,
		/// Pair of key and values from this state.
		pub key_values: Vec<(Vec<u8>, Vec<u8>)>,
	}

	impl<I> From<I> for KeyValueStates
	where
		I: IntoIterator<Item = (Vec<u8>, (Vec<(Vec<u8>, Vec<u8>)>, Vec<Vec<u8>>))>,
	{
		fn from(b: I) -> Self {
			let mut result = Vec::new();
			for (state_root, (key_values, storage_paths)) in b.into_iter() {
				result.push(KeyValueStorageLevel {
					state_root,
					key_values,
					parent_storage_keys: storage_paths,
				})
			}
			KeyValueStates(result)
		}
	}

	impl KeyValueStates {
		/// Return total number of key values in states.
		pub fn len(&self) -> usize {
			self.0.iter().fold(0, |nb, state| nb + state.key_values.len())
		}

		/// Update last keys accessed from this state.
		pub fn update_last_key(
			&self,
			stopped_at: usize,
			last: &mut SmallVec<[Vec<u8>; 2]>,
		) -> bool {
			if stopped_at == 0 || stopped_at > MAX_NESTED_TRIE_DEPTH {
				return false
			}
			match stopped_at {
				1 => {
					let top_last =
						self.0.get(0).and_then(|s| s.key_values.last().map(|kv| kv.0.clone()));
					if let Some(top_last) = top_last {
						match last.len() {
							0 => {
								last.push(top_last);
								return true
							},
							2 => {
								last.pop();
							},
							_ => (),
						}
						// update top trie access.
						last[0] = top_last;
						return true
					} else {
						// No change in top trie accesses.
						// Indicates end of reading of a child trie.
						last.truncate(1);
						return true
					}
				},
				2 => {
					let top_last =
						self.0.get(0).and_then(|s| s.key_values.last().map(|kv| kv.0.clone()));
					let child_last =
						self.0.last().and_then(|s| s.key_values.last().map(|kv| kv.0.clone()));

					if let Some(child_last) = child_last {
						if last.is_empty() {
							if let Some(top_last) = top_last {
								last.push(top_last)
							} else {
								return false
							}
						} else if let Some(top_last) = top_last {
							last[0] = top_last;
						}
						if last.len() == 2 {
							last.pop();
						}
						last.push(child_last);
						return true
					} else {
						// stopped at level 2 so child last is define.
						return false
					}
				},
				_ => (),
			}
			false
		}
	}

	/// Generate range storage read proof, with child tries
	/// content.
	/// A size limit is applied to the proof with the
	/// exception that `start_at` and its following element
	/// are always part of the proof.
	/// If a key different than `start_at` is a child trie root,
	/// the child trie content will be included in the proof.
	pub fn prove_range_read_with_child_with_size<B, H>(
		backend: B,
		size_limit: usize,
		start_at: &[Vec<u8>],
	) -> Result<(StorageProof, u32), Box<dyn Error>>
	where
		B: AsTrieBackend<H>,
		H: Hasher,
		H::Out: Ord + Codec,
	{
		let trie_backend = backend.as_trie_backend();
		prove_range_read_with_child_with_size_on_trie_backend(trie_backend, size_limit, start_at)
	}

	/// Generate range storage read proof, with child tries
	/// content.
	/// See `prove_range_read_with_child_with_size`.
	pub fn prove_range_read_with_child_with_size_on_trie_backend<S, H>(
		trie_backend: &TrieBackend<S, H>,
		size_limit: usize,
		start_at: &[Vec<u8>],
	) -> Result<(StorageProof, u32), Box<dyn Error>>
	where
		S: trie_backend_essence::TrieBackendStorage<H>,
		H: Hasher,
		H::Out: Ord + Codec,
	{
		if start_at.len() > MAX_NESTED_TRIE_DEPTH {
			return Err(Box::new("Invalid start of range."))
		}

		let recorder = sp_trie::recorder::Recorder::default();
		let proving_backend =
			TrieBackendBuilder::wrap(trie_backend).with_recorder(recorder.clone()).build();
		let mut count = 0;

		let mut child_roots = HashSet::new();
		let (mut child_key, mut start_at) = if start_at.len() == 2 {
			let storage_key = start_at.get(0).expect("Checked length.").clone();
			if let Some(state_root) = proving_backend
				.storage(&storage_key)
				.map_err(|e| Box::new(e) as Box<dyn Error>)?
			{
				child_roots.insert(state_root);
			} else {
				return Err(Box::new("Invalid range start child trie key."))
			}

			(Some(storage_key), start_at.get(1).cloned())
		} else {
			(None, start_at.get(0).cloned())
		};

		loop {
			let (child_info, depth) = if let Some(storage_key) = child_key.as_ref() {
				let storage_key = PrefixedStorageKey::new_ref(storage_key);
				(
					Some(match ChildType::from_prefixed_key(storage_key) {
						Some((ChildType::ParentKeyId, storage_key)) =>
							ChildInfo::new_default(storage_key),
						None => return Err(Box::new("Invalid range start child trie key.")),
					}),
					2,
				)
			} else {
				(None, 1)
			};

			let start_at_ref = start_at.as_ref().map(AsRef::as_ref);
			let mut switch_child_key = None;
			let mut first = start_at.is_some();
			let completed = proving_backend
				.apply_to_key_values_while(
					child_info.as_ref(),
					None,
					start_at_ref,
					|key, value| {
						if first &&
							start_at_ref
								.as_ref()
								.map(|start| &key.as_slice() > start)
								.unwrap_or(true)
						{
							first = false;
						}

						if first {
							true
						} else if depth < MAX_NESTED_TRIE_DEPTH &&
							sp_core::storage::well_known_keys::is_child_storage_key(
								key.as_slice(),
							) {
							count += 1;
							if !child_roots.contains(value.as_slice()) {
								child_roots.insert(value);
								switch_child_key = Some(key);
								false
							} else {
								// do not add two child trie with same root
								true
							}
						} else if recorder.estimate_encoded_size() <= size_limit {
							count += 1;
							true
						} else {
							false
						}
					},
					false,
				)
				.map_err(|e| Box::new(e) as Box<dyn Error>)?;

			if switch_child_key.is_none() {
				if depth == 1 {
					break
				} else if completed {
					start_at = child_key.take();
				} else {
					break
				}
			} else {
				child_key = switch_child_key;
				start_at = None;
			}
		}

		let proof = proving_backend
			.extract_proof()
			.expect("A recorder was set and thus, a storage proof can be extracted; qed");
		Ok((proof, count))
	}

	/// Generate range storage read proof.
	pub fn prove_range_read_with_size<B, H>(
		backend: B,
		child_info: Option<&ChildInfo>,
		prefix: Option<&[u8]>,
		size_limit: usize,
		start_at: Option<&[u8]>,
	) -> Result<(StorageProof, u32), Box<dyn Error>>
	where
		B: AsTrieBackend<H>,
		H: Hasher,
		H::Out: Ord + Codec,
	{
		let trie_backend = backend.as_trie_backend();
		prove_range_read_with_size_on_trie_backend(
			trie_backend,
			child_info,
			prefix,
			size_limit,
			start_at,
		)
	}

	/// Generate range storage read proof on an existing trie backend.
	pub fn prove_range_read_with_size_on_trie_backend<S, H>(
		trie_backend: &TrieBackend<S, H>,
		child_info: Option<&ChildInfo>,
		prefix: Option<&[u8]>,
		size_limit: usize,
		start_at: Option<&[u8]>,
	) -> Result<(StorageProof, u32), Box<dyn Error>>
	where
		S: trie_backend_essence::TrieBackendStorage<H>,
		H: Hasher,
		H::Out: Ord + Codec,
	{
		let recorder = sp_trie::recorder::Recorder::default();
		let proving_backend =
			TrieBackendBuilder::wrap(trie_backend).with_recorder(recorder.clone()).build();
		let mut count = 0;
		proving_backend
			.apply_to_key_values_while(
				child_info,
				prefix,
				start_at,
				|_key, _value| {
					if count == 0 || recorder.estimate_encoded_size() <= size_limit {
						count += 1;
						true
					} else {
						false
					}
				},
				false,
			)
			.map_err(|e| Box::new(e) as Box<dyn Error>)?;

		let proof = proving_backend
			.extract_proof()
			.expect("A recorder was set and thus, a storage proof can be extracted; qed");
		Ok((proof, count))
	}

	/// Generate child storage read proof.
	pub fn prove_child_read<B, H, I>(
		backend: B,
		child_info: &ChildInfo,
		keys: I,
	) -> Result<StorageProof, Box<dyn Error>>
	where
		B: AsTrieBackend<H>,
		H: Hasher,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let trie_backend = backend.as_trie_backend();
		prove_child_read_on_trie_backend(trie_backend, child_info, keys)
	}

	/// Generate storage read proof on pre-created trie backend.
	pub fn prove_read_on_trie_backend<S, H, I>(
		trie_backend: &TrieBackend<S, H>,
		keys: I,
	) -> Result<StorageProof, Box<dyn Error>>
	where
		S: trie_backend_essence::TrieBackendStorage<H>,
		H: Hasher,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let proving_backend =
			TrieBackendBuilder::wrap(trie_backend).with_recorder(Default::default()).build();
		for key in keys.into_iter() {
			proving_backend
				.storage(key.as_ref())
				.map_err(|e| Box::new(e) as Box<dyn Error>)?;
		}

		Ok(proving_backend
			.extract_proof()
			.expect("A recorder was set and thus, a storage proof can be extracted; qed"))
	}

	/// Generate storage read proof on pre-created trie backend.
	pub fn prove_child_read_on_trie_backend<S, H, I>(
		trie_backend: &TrieBackend<S, H>,
		child_info: &ChildInfo,
		keys: I,
	) -> Result<StorageProof, Box<dyn Error>>
	where
		S: trie_backend_essence::TrieBackendStorage<H>,
		H: Hasher,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let proving_backend =
			TrieBackendBuilder::wrap(trie_backend).with_recorder(Default::default()).build();
		for key in keys.into_iter() {
			proving_backend
				.child_storage(child_info, key.as_ref())
				.map_err(|e| Box::new(e) as Box<dyn Error>)?;
		}

		Ok(proving_backend
			.extract_proof()
			.expect("A recorder was set and thus, a storage proof can be extracted; qed"))
	}

	/// Check storage read proof, generated by `prove_read` call.
	pub fn read_proof_check<H, I>(
		root: H::Out,
		proof: StorageProof,
		keys: I,
	) -> Result<HashMap<Vec<u8>, Option<Vec<u8>>>, Box<dyn Error>>
	where
		H: Hasher + 'static,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let proving_backend = create_proof_check_backend::<H>(root, proof)?;
		let mut result = HashMap::new();
		for key in keys.into_iter() {
			let value = read_proof_check_on_proving_backend(&proving_backend, key.as_ref())?;
			result.insert(key.as_ref().to_vec(), value);
		}
		Ok(result)
	}

	/// Check storage range proof with child trie included, generated by
	/// `prove_range_read_with_child_with_size` call.
	///
	/// Returns key values contents and the depth of the pending state iteration
	/// (0 if completed).
	pub fn read_range_proof_check_with_child<H>(
		root: H::Out,
		proof: StorageProof,
		start_at: &[Vec<u8>],
	) -> Result<(KeyValueStates, usize), Box<dyn Error>>
	where
		H: Hasher + 'static,
		H::Out: Ord + Codec,
	{
		let proving_backend = create_proof_check_backend::<H>(root, proof)?;
		read_range_proof_check_with_child_on_proving_backend(&proving_backend, start_at)
	}

	/// Check child storage range proof, generated by `prove_range_read_with_size` call.
	pub fn read_range_proof_check<H>(
		root: H::Out,
		proof: StorageProof,
		child_info: Option<&ChildInfo>,
		prefix: Option<&[u8]>,
		count: Option<u32>,
		start_at: Option<&[u8]>,
	) -> Result<(Vec<(Vec<u8>, Vec<u8>)>, bool), Box<dyn Error>>
	where
		H: Hasher + 'static,
		H::Out: Ord + Codec,
	{
		let proving_backend = create_proof_check_backend::<H>(root, proof)?;
		read_range_proof_check_on_proving_backend(
			&proving_backend,
			child_info,
			prefix,
			count,
			start_at,
		)
	}

	/// Check child storage read proof, generated by `prove_child_read` call.
	pub fn read_child_proof_check<H, I>(
		root: H::Out,
		proof: StorageProof,
		child_info: &ChildInfo,
		keys: I,
	) -> Result<HashMap<Vec<u8>, Option<Vec<u8>>>, Box<dyn Error>>
	where
		H: Hasher + 'static,
		H::Out: Ord + Codec,
		I: IntoIterator,
		I::Item: AsRef<[u8]>,
	{
		let proving_backend = create_proof_check_backend::<H>(root, proof)?;
		let mut result = HashMap::new();
		for key in keys.into_iter() {
			let value = read_child_proof_check_on_proving_backend(
				&proving_backend,
				child_info,
				key.as_ref(),
			)?;
			result.insert(key.as_ref().to_vec(), value);
		}
		Ok(result)
	}