lib.rs

// This file is part of Substrate.

// Copyright (C) 2017-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! I/O host interface for substrate runtime.

#![warn(missing_docs)]

#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(not(feature = "std"), feature(alloc_error_handler))]

#![cfg_attr(feature = "std",
   doc = "Substrate runtime standard library as compiled when linked with Rust's standard library.")]
#![cfg_attr(not(feature = "std"),
   doc = "Substrate's runtime standard library as compiled without Rust's standard library.")]

use sp_std::vec::Vec;

#[cfg(feature = "std")]
use sp_std::ops::Deref;

#[cfg(feature = "std")]
use tracing;

#[cfg(feature = "std")]
use sp_core::{
	crypto::Pair,
	traits::{TaskExecutorExt, RuntimeSpawnExt},
	offchain::{OffchainDbExt, OffchainWorkerExt, TransactionPoolExt},
	hexdisplay::HexDisplay,
	storage::ChildInfo,
};
#[cfg(feature = "std")]
use sp_keystore::{KeystoreExt, SyncCryptoStore};

use sp_core::{
	OpaquePeerId, crypto::KeyTypeId, ed25519, sr25519, ecdsa, H256, LogLevel, LogLevelFilter,
	offchain::{
		Timestamp, HttpRequestId, HttpRequestStatus, HttpError, StorageKind, OpaqueNetworkState,
	},
};

#[cfg(feature = "std")]
use sp_trie::{TrieConfiguration, trie_types::Layout};

use sp_runtime_interface::{runtime_interface, Pointer};
use sp_runtime_interface::pass_by::{PassBy, PassByCodec};

use codec::{Encode, Decode};

#[cfg(feature = "std")]
use sp_externalities::{ExternalitiesExt, Externalities};

#[cfg(feature = "std")]
mod batch_verifier;

#[cfg(feature = "std")]
use batch_verifier::BatchVerifier;

const LOG_TARGET: &str = "runtime::io";

/// Error verifying ECDSA signature
#[derive(Encode, Decode)]
pub enum EcdsaVerifyError {
	/// Incorrect value of R or S
	BadRS,
	/// Incorrect value of V
	BadV,
	/// Invalid signature
	BadSignature,
}

/// The outcome of calling `storage_kill`. Returned value is the number of storage items
/// removed from the trie from making the `storage_kill` call.
#[derive(PassByCodec, Encode, Decode)]
pub enum KillChildStorageResult {
	/// No key remains in the child trie.
	AllRemoved(u32),
	/// At least one key still resides in the child trie due to the supplied limit.
	SomeRemaining(u32),
}

/// Interface for accessing the storage from within the runtime.
#[runtime_interface]
pub trait Storage {
	/// Returns the data for `key` in the storage or `None` if the key can not be found.
	fn get(&self, key: &[u8]) -> Option<Vec<u8>> {
		self.storage(key).map(|s| s.to_vec())
	}

	/// Get `key` from storage, placing the value into `value_out` and return the number of
	/// bytes that the entry in storage has beyond the offset or `None` if the storage entry
	/// doesn't exist at all.
	/// If `value_out` length is smaller than the returned length, only `value_out` length bytes
	/// are copied into `value_out`.
	fn read(&self, key: &[u8], value_out: &mut [u8], value_offset: u32) -> Option<u32> {
		self.storage(key).map(|value| {
			let value_offset = value_offset as usize;
			let data = &value[value_offset.min(value.len())..];
			let written = std::cmp::min(data.len(), value_out.len());
			value_out[..written].copy_from_slice(&data[..written]);
			data.len() as u32
		})
	}

	/// Set `key` to `value` in the storage.
	fn set(&mut self, key: &[u8], value: &[u8]) {
		self.set_storage(key.to_vec(), value.to_vec());
	}

	/// Clear the storage of the given `key` and its value.
	fn clear(&mut self, key: &[u8]) {
		self.clear_storage(key)
	}

	/// Check whether the given `key` exists in storage.
	fn exists(&self, key: &[u8]) -> bool {
		self.exists_storage(key)
	}

	/// Clear the storage of each key-value pair where the key starts with the given `prefix`.
	fn clear_prefix(&mut self, prefix: &[u8]) {
		Externalities::clear_prefix(*self, prefix)
	}

	/// Append the encoded `value` to the storage item at `key`.
	///
	/// The storage item needs to implement [`EncodeAppend`](codec::EncodeAppend).
	///
	/// # Warning
	///
	/// If the storage item does not support [`EncodeAppend`](codec::EncodeAppend) or
	/// something else fails at appending, the storage item will be set to `[value]`.
	fn append(&mut self, key: &[u8], value: Vec<u8>) {
		self.storage_append(key.to_vec(), value);
	}

	/// "Commit" all existing operations and compute the resulting storage root.
	///
	/// The hashing algorithm is defined by the `Block`.
	///
	/// Returns a `Vec<u8>` that holds the SCALE encoded hash.
	fn root(&mut self) -> Vec<u8> {
		self.storage_root()
	}

	/// "Commit" all existing operations and get the resulting storage change root.
	/// `parent_hash` is a SCALE encoded hash.
	///
	/// The hashing algorithm is defined by the `Block`.
	///
	/// Returns `Some(Vec<u8>)` which holds the SCALE encoded hash or `None` when
	/// changes trie is disabled.
	fn changes_root(&mut self, parent_hash: &[u8]) -> Option<Vec<u8>> {
		self.storage_changes_root(parent_hash)
			.expect("Invalid `parent_hash` given to `changes_root`.")
	}

	/// Get the next key in storage after the given one in lexicographic order.
	fn next_key(&mut self, key: &[u8]) -> Option<Vec<u8>> {
		self.next_storage_key(&key)
	}

	/// Start a new nested transaction.
	///
	/// This allows to either commit or roll back all changes that are made after this call.
	/// For every transaction there must be a matching call to either `rollback_transaction`
	/// or `commit_transaction`. This is also effective for all values manipulated using the
	/// `DefaultChildStorage` API.
	///
	/// # Warning
	///
	/// This is a low level API that is potentially dangerous as it can easily result
	/// in unbalanced transactions. For example, FRAME users should use high level storage
	/// abstractions.
	fn start_transaction(&mut self) {
		self.storage_start_transaction();
	}

	/// Rollback the last transaction started by `start_transaction`.
	///
	/// Any changes made during that transaction are discarded.
	///
	/// # Panics
	///
	/// Will panic if there is no open transaction.
	fn rollback_transaction(&mut self) {
		self.storage_rollback_transaction()
			.expect("No open transaction that can be rolled back.");
	}

	/// Commit the last transaction started by `start_transaction`.
	///
	/// Any changes made during that transaction are committed.
	///
	/// # Panics
	///
	/// Will panic if there is no open transaction.
	fn commit_transaction(&mut self) {
		self.storage_commit_transaction()
			.expect("No open transaction that can be committed.");
	}
}

/// Interface for accessing the child storage for default child trie,
/// from within the runtime.
#[runtime_interface]
pub trait DefaultChildStorage {
	/// Get a default child storage value for a given key.
	///
	/// Parameter `storage_key` is the unprefixed location of the root of the child trie in the parent trie.
	/// Result is `None` if the value for `key` in the child storage can not be found.
	fn get(
		&self,
		storage_key: &[u8],
		key: &[u8],
	) -> Option<Vec<u8>> {
		let child_info = ChildInfo::new_default(storage_key);
		self.child_storage(&child_info, key).map(|s| s.to_vec())
	}

	/// Allocation efficient variant of `get`.
	///
	/// Get `key` from child storage, placing the value into `value_out` and return the number
	/// of bytes that the entry in storage has beyond the offset or `None` if the storage entry
	/// doesn't exist at all.
	/// If `value_out` length is smaller than the returned length, only `value_out` length bytes
	/// are copied into `value_out`.
	fn read(
		&self,
		storage_key: &[u8],
		key: &[u8],
		value_out: &mut [u8],
		value_offset: u32,
	) -> Option<u32> {
		let child_info = ChildInfo::new_default(storage_key);
		self.child_storage(&child_info, key)
			.map(|value| {
				let value_offset = value_offset as usize;
				let data = &value[value_offset.min(value.len())..];
				let written = std::cmp::min(data.len(), value_out.len());
				value_out[..written].copy_from_slice(&data[..written]);
				data.len() as u32
			})
	}

	/// Set a child storage value.
	///
	/// Set `key` to `value` in the child storage denoted by `storage_key`.
	fn set(
		&mut self,
		storage_key: &[u8],
		key: &[u8],
		value: &[u8],
	) {
		let child_info = ChildInfo::new_default(storage_key);
		self.set_child_storage(&child_info, key.to_vec(), value.to_vec());
	}

	/// Clear a child storage key.
	///
	/// For the default child storage at `storage_key`, clear value at `key`.
	fn clear(
		&mut self,
		storage_key: &[u8],
		key: &[u8],
	) {
		let child_info = ChildInfo::new_default(storage_key);
		self.clear_child_storage(&child_info, key);
	}

	/// Clear an entire child storage.
	///
	/// If it exists, the child storage for `storage_key`
	/// is removed.
	fn storage_kill(
		&mut self,
		storage_key: &[u8],
	) {
		let child_info = ChildInfo::new_default(storage_key);
		self.kill_child_storage(&child_info, None);
	}

	/// Clear a child storage key.
	///
	/// Deletes all keys from the overlay and up to `limit` keys from the backend if
	/// it is set to `Some`. No limit is applied when `limit` is set to `None`.
	///
	/// The limit can be used to partially delete a child trie in case it is too large
	/// to delete in one go (block).
	///
	/// It returns a boolean false iff some keys are remaining in
	/// the child trie after the functions returns.
	///
	/// # Note
	///
	/// Please note that keys that are residing in the overlay for that child trie when
	/// issuing this call are all deleted without counting towards the `limit`. Only keys
	/// written during the current block are part of the overlay. Deleting with a `limit`
	/// mostly makes sense with an empty overlay for that child trie.
	///
	/// Calling this function multiple times per block for the same `storage_key` does
	/// not make much sense because it is not cumulative when called inside the same block.
	/// Use this function to distribute the deletion of a single child trie across multiple
	/// blocks.
	#[version(2)]
	fn storage_kill(&mut self, storage_key: &[u8], limit: Option<u32>) -> bool {
		let child_info = ChildInfo::new_default(storage_key);
		let (all_removed, _num_removed) = self.kill_child_storage(&child_info, limit);
		all_removed
	}

	/// Clear a child storage key.
	///
	/// Deletes all keys from the overlay and up to `limit` keys from the backend if
	/// it is set to `Some`. No limit is applied when `limit` is set to `None`.
	///
	/// The limit can be used to partially delete a child trie in case it is too large
	/// to delete in one go (block).
	///
	/// It returns a boolean false iff some keys are remaining in
	/// the child trie after the functions returns. Also returns a `u32` with
	/// the number of keys removed from the process.
	///
	/// # Note
	///
	/// Please note that keys that are residing in the overlay for that child trie when
	/// issuing this call are all deleted without counting towards the `limit`. Only keys
	/// written during the current block are part of the overlay. Deleting with a `limit`
	/// mostly makes sense with an empty overlay for that child trie.
	///
	/// Calling this function multiple times per block for the same `storage_key` does
	/// not make much sense because it is not cumulative when called inside the same block.
	/// Use this function to distribute the deletion of a single child trie across multiple
	/// blocks.
	#[version(3)]
	fn storage_kill(&mut self, storage_key: &[u8], limit: Option<u32>) -> KillChildStorageResult {
		let child_info = ChildInfo::new_default(storage_key);
		let (all_removed, num_removed) = self.kill_child_storage(&child_info, limit);
		match all_removed {
			true => KillChildStorageResult::AllRemoved(num_removed),
			false => KillChildStorageResult::SomeRemaining(num_removed),
		}
	}

	/// Check a child storage key.
	///
	/// Check whether the given `key` exists in default child defined at `storage_key`.
	fn exists(
		&self,
		storage_key: &[u8],
		key: &[u8],
	) -> bool {
		let child_info = ChildInfo::new_default(storage_key);
		self.exists_child_storage(&child_info, key)
	}

	/// Clear child default key by prefix.
	///
	/// Clear the child storage of each key-value pair where the key starts with the given `prefix`.
	fn clear_prefix(
		&mut self,
		storage_key: &[u8],
		prefix: &[u8],
	) {
		let child_info = ChildInfo::new_default(storage_key);
		self.clear_child_prefix(&child_info, prefix);
	}

	/// Default child root calculation.
	///
	/// "Commit" all existing operations and compute the resulting child storage root.
	/// The hashing algorithm is defined by the `Block`.
	///
	/// Returns a `Vec<u8>` that holds the SCALE encoded hash.
	fn root(
		&mut self,
		storage_key: &[u8],
	) -> Vec<u8> {
		let child_info = ChildInfo::new_default(storage_key);
		self.child_storage_root(&child_info)
	}

	/// Child storage key iteration.
	///
	/// Get the next key in storage after the given one in lexicographic order in child storage.
	fn next_key(
		&mut self,
		storage_key: &[u8],
		key: &[u8],
	) -> Option<Vec<u8>> {
		let child_info = ChildInfo::new_default(storage_key);
		self.next_child_storage_key(&child_info, key)
	}
}

/// Interface that provides trie related functionality.
#[runtime_interface]
pub trait Trie {
	/// A trie root formed from the iterated items.
	fn blake2_256_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
		Layout::<sp_core::Blake2Hasher>::trie_root(input)
	}

	/// A trie root formed from the enumerated items.
	fn blake2_256_ordered_root(input: Vec<Vec<u8>>) -> H256 {
		Layout::<sp_core::Blake2Hasher>::ordered_trie_root(input)
	}

	/// A trie root formed from the iterated items.
	fn keccak_256_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
		Layout::<sp_core::KeccakHasher>::trie_root(input)
	}

	/// A trie root formed from the enumerated items.
	fn keccak_256_ordered_root(input: Vec<Vec<u8>>) -> H256 {
		Layout::<sp_core::KeccakHasher>::ordered_trie_root(input)
	}

	/// Verify trie proof
	fn blake2_256_verify_proof(root: H256, proof: &[Vec<u8>], key: &[u8], value: &[u8]) -> bool {
		sp_trie::verify_trie_proof::<Layout<sp_core::Blake2Hasher>, _, _, _>(
			&root,
			proof,
			&[(key, Some(value))],
		).is_ok()
	}

	/// Verify trie proof
	fn keccak_256_verify_proof(root: H256, proof: &[Vec<u8>], key: &[u8], value: &[u8]) -> bool {
		sp_trie::verify_trie_proof::<Layout<sp_core::KeccakHasher>, _, _, _>(
			&root,
			proof,
			&[(key, Some(value))],
		).is_ok()
	}
}

/// Interface that provides miscellaneous functions for communicating between the runtime and the node.
#[runtime_interface]
pub trait Misc {
	// NOTE: We use the target 'runtime' for messages produced by general printing functions, instead
	// of LOG_TARGET.

	/// Print a number.
	fn print_num(val: u64) {
		log::debug!(target: "runtime", "{}", val);
	}

	/// Print any valid `utf8` buffer.
	fn print_utf8(utf8: &[u8]) {
		if let Ok(data) = std::str::from_utf8(utf8) {
			log::debug!(target: "runtime", "{}", data)
		}
	}

	/// Print any `u8` slice as hex.
	fn print_hex(data: &[u8]) {
		log::debug!(target: "runtime", "{}", HexDisplay::from(&data));
	}

	/// Extract the runtime version of the given wasm blob by calling `Core_version`.
	///
	/// Returns `None` if calling the function failed for any reason or `Some(Vec<u8>)` where
	/// the `Vec<u8>` holds the SCALE encoded runtime version.
	///
	/// # Performance
	///
	/// This function may be very expensive to call depending on the wasm binary. It may be
	/// relatively cheap if the wasm binary contains version information. In that case, uncompression
	/// of the wasm blob is the dominating factor.
	///
	/// If the wasm binary does not have the version information attached, then a legacy mechanism
	/// may be involved. This means that a runtime call will be performed to query the version.
	///
	/// Calling into the runtime may be incredible expensive and should be approached with care.
	fn runtime_version(&mut self, wasm: &[u8]) -> Option<Vec<u8>> {
		use sp_core::traits::ReadRuntimeVersionExt;

		let mut ext = sp_state_machine::BasicExternalities::default();

		match self
			.extension::<ReadRuntimeVersionExt>()
			.expect("No `ReadRuntimeVersionExt` associated for the current context!")
			.read_runtime_version(wasm, &mut ext)
		{
			Ok(v) => Some(v),
			Err(err) => {
				log::debug!(
					target: LOG_TARGET,
					"cannot read version from the given runtime: {}",
					err,
				);
				None
			}
		}
	}
}

/// Interfaces for working with crypto related types from within the runtime.
#[runtime_interface]
pub trait Crypto {
	/// Returns all `ed25519` public keys for the given key id from the keystore.
	fn ed25519_public_keys(&mut self, id: KeyTypeId) -> Vec<ed25519::Public> {
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::ed25519_public_keys(keystore, id)
	}

	/// Generate an `ed22519` key for the given key type using an optional `seed` and
	/// store it in the keystore.
	///
	/// The `seed` needs to be a valid utf8.
	///
	/// Returns the public key.
	fn ed25519_generate(&mut self, id: KeyTypeId, seed: Option<Vec<u8>>) -> ed25519::Public {
		let seed = seed.as_ref().map(|s| std::str::from_utf8(&s).expect("Seed is valid utf8!"));
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::ed25519_generate_new(keystore, id, seed)
			.expect("`ed25519_generate` failed")
	}

	/// Sign the given `msg` with the `ed25519` key that corresponds to the given public key and
	/// key type in the keystore.
	///
	/// Returns the signature.
	fn ed25519_sign(
		&mut self,
		id: KeyTypeId,
		pub_key: &ed25519::Public,
		msg: &[u8],
	) -> Option<ed25519::Signature> {
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::sign_with(keystore, id, &pub_key.into(), msg)
			.ok()
			.flatten()
			.map(|sig| ed25519::Signature::from_slice(sig.as_slice()))
	}

	/// Verify `ed25519` signature.
	///
	/// Returns `true` when the verification was successful.
	fn ed25519_verify(
		sig: &ed25519::Signature,
		msg: &[u8],
		pub_key: &ed25519::Public,
	) -> bool {
		ed25519::Pair::verify(sig, msg, pub_key)
	}

	/// Register a `ed25519` signature for batch verification.
	///
	/// Batch verification must be enabled by calling [`start_batch_verify`].
	/// If batch verification is not enabled, the signature will be verified immediatley.
	/// To get the result of the batch verification, [`finish_batch_verify`]
	/// needs to be called.
	///
	/// Returns `true` when the verification is either successful or batched.
	fn ed25519_batch_verify(
		&mut self,
		sig: &ed25519::Signature,
		msg: &[u8],
		pub_key: &ed25519::Public,
	) -> bool {
		self.extension::<VerificationExt>().map(
			|extension| extension.push_ed25519(sig.clone(), pub_key.clone(), msg.to_vec())
		).unwrap_or_else(|| ed25519_verify(sig, msg, pub_key))
	}

	/// Verify `sr25519` signature.
	///
	/// Returns `true` when the verification was successful.
	#[version(2)]
	fn sr25519_verify(
		sig: &sr25519::Signature,
		msg: &[u8],
		pub_key: &sr25519::Public,
	) -> bool {
		sr25519::Pair::verify(sig, msg, pub_key)
	}

	/// Register a `sr25519` signature for batch verification.
	///
	/// Batch verification must be enabled by calling [`start_batch_verify`].
	/// If batch verification is not enabled, the signature will be verified immediatley.
	/// To get the result of the batch verification, [`finish_batch_verify`]
	/// needs to be called.
	///
	/// Returns `true` when the verification is either successful or batched.
	fn sr25519_batch_verify(
		&mut self,
		sig: &sr25519::Signature,
		msg: &[u8],
		pub_key: &sr25519::Public,
	) -> bool {
		self.extension::<VerificationExt>().map(
			|extension| extension.push_sr25519(sig.clone(), pub_key.clone(), msg.to_vec())
		).unwrap_or_else(|| sr25519_verify(sig, msg, pub_key))
	}

	/// Start verification extension.
	fn start_batch_verify(&mut self) {
		let scheduler = self.extension::<TaskExecutorExt>()
			.expect("No task executor associated with the current context!")
			.clone();

		self.register_extension(VerificationExt(BatchVerifier::new(scheduler)))
			.expect("Failed to register required extension: `VerificationExt`");
	}

	/// Finish batch-verification of signatures.
	///
	/// Verify or wait for verification to finish for all signatures which were previously
	/// deferred by `sr25519_verify`/`ed25519_verify`.
	///
	/// Will panic if no `VerificationExt` is registered (`start_batch_verify` was not called).
	fn finish_batch_verify(&mut self) -> bool {
		let result = self.extension::<VerificationExt>()
			.expect("`finish_batch_verify` should only be called after `start_batch_verify`")
			.verify_and_clear();

		self.deregister_extension::<VerificationExt>()
			.expect("No verification extension in current context!");

		result
	}

	/// Returns all `sr25519` public keys for the given key id from the keystore.
	fn sr25519_public_keys(&mut self, id: KeyTypeId) -> Vec<sr25519::Public> {
		let keystore = &*** self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::sr25519_public_keys(keystore, id)
	}

	/// Generate an `sr22519` key for the given key type using an optional seed and
	/// store it in the keystore.
	///
	/// The `seed` needs to be a valid utf8.
	///
	/// Returns the public key.
	fn sr25519_generate(&mut self, id: KeyTypeId, seed: Option<Vec<u8>>) -> sr25519::Public {
		let seed = seed.as_ref().map(|s| std::str::from_utf8(&s).expect("Seed is valid utf8!"));
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::sr25519_generate_new(keystore, id, seed)
			.expect("`sr25519_generate` failed")
	}

	/// Sign the given `msg` with the `sr25519` key that corresponds to the given public key and
	/// key type in the keystore.
	///
	/// Returns the signature.
	fn sr25519_sign(
		&mut self,
		id: KeyTypeId,
		pub_key: &sr25519::Public,
		msg: &[u8],
	) -> Option<sr25519::Signature> {
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::sign_with(keystore, id, &pub_key.into(), msg)
			.ok()
			.flatten()
			.map(|sig| sr25519::Signature::from_slice(sig.as_slice()))
	}

	/// Verify an `sr25519` signature.
	///
	/// Returns `true` when the verification in successful regardless of
	/// signature version.
	fn sr25519_verify(sig: &sr25519::Signature, msg: &[u8], pubkey: &sr25519::Public) -> bool {
		sr25519::Pair::verify_deprecated(sig, msg, pubkey)
	}

	/// Returns all `ecdsa` public keys for the given key id from the keystore.
	fn ecdsa_public_keys(&mut self, id: KeyTypeId) -> Vec<ecdsa::Public> {
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::ecdsa_public_keys(keystore, id)
	}

	/// Generate an `ecdsa` key for the given key type using an optional `seed` and
	/// store it in the keystore.
	///
	/// The `seed` needs to be a valid utf8.
	///
	/// Returns the public key.
	fn ecdsa_generate(&mut self, id: KeyTypeId, seed: Option<Vec<u8>>) -> ecdsa::Public {
		let seed = seed.as_ref().map(|s| std::str::from_utf8(&s).expect("Seed is valid utf8!"));
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::ecdsa_generate_new(keystore, id, seed)
			.expect("`ecdsa_generate` failed")
	}

	/// Sign the given `msg` with the `ecdsa` key that corresponds to the given public key and
	/// key type in the keystore.
	///
	/// Returns the signature.
	fn ecdsa_sign(
		&mut self,
		id: KeyTypeId,
		pub_key: &ecdsa::Public,
		msg: &[u8],
	) -> Option<ecdsa::Signature> {
		let keystore = &***self.extension::<KeystoreExt>()
			.expect("No `keystore` associated for the current context!");
		SyncCryptoStore::sign_with(keystore, id, &pub_key.into(), msg)
			.ok()
			.flatten()
			.map(|sig| ecdsa::Signature::from_slice(sig.as_slice()))
	}

	/// Verify `ecdsa` signature.
	///
	/// Returns `true` when the verification was successful.
	fn ecdsa_verify(
		sig: &ecdsa::Signature,
		msg: &[u8],
		pub_key: &ecdsa::Public,
	) -> bool {
		ecdsa::Pair::verify(sig, msg, pub_key)
	}

	/// Register a `ecdsa` signature for batch verification.
	///
	/// Batch verification must be enabled by calling [`start_batch_verify`].
	/// If batch verification is not enabled, the signature will be verified immediatley.
	/// To get the result of the batch verification, [`finish_batch_verify`]
	/// needs to be called.
	///
	/// Returns `true` when the verification is either successful or batched.
	fn ecdsa_batch_verify(
		&mut self,
		sig: &ecdsa::Signature,
		msg: &[u8],
		pub_key: &ecdsa::Public,
	) -> bool {
		self.extension::<VerificationExt>().map(
			|extension| extension.push_ecdsa(sig.clone(), pub_key.clone(), msg.to_vec())
		).unwrap_or_else(|| ecdsa_verify(sig, msg, pub_key))
	}

	/// Verify and recover a SECP256k1 ECDSA signature.
	///
	/// - `sig` is passed in RSV format. V should be either `0/1` or `27/28`.
	/// - `msg` is the blake2-256 hash of the message.
	///
	/// Returns `Err` if the signature is bad, otherwise the 64-byte pubkey
	/// (doesn't include the 0x04 prefix).
	fn secp256k1_ecdsa_recover(
		sig: &[u8; 65],
		msg: &[u8; 32],
	) -> Result<[u8; 64], EcdsaVerifyError> {
		let rs = secp256k1::Signature::parse_slice(&sig[0..64])
			.map_err(|_| EcdsaVerifyError::BadRS)?;
		let v = secp256k1::RecoveryId::parse(if sig[64] > 26 { sig[64] - 27 } else { sig[64] } as u8)
			.map_err(|_| EcdsaVerifyError::BadV)?;
		let pubkey = secp256k1::recover(&secp256k1::Message::parse(msg), &rs, &v)
			.map_err(|_| EcdsaVerifyError::BadSignature)?;
		let mut res = [0u8; 64];
		res.copy_from_slice(&pubkey.serialize()[1..65]);
		Ok(res)
	}

	/// Verify and recover a SECP256k1 ECDSA signature.
	///
	/// - `sig` is passed in RSV format. V should be either `0/1` or `27/28`.
	/// - `msg` is the blake2-256 hash of the message.
	///
	/// Returns `Err` if the signature is bad, otherwise the 33-byte compressed pubkey.
	fn secp256k1_ecdsa_recover_compressed(
		sig: &[u8; 65],
		msg: &[u8; 32],
	) -> Result<[u8; 33], EcdsaVerifyError> {
		let rs = secp256k1::Signature::parse_slice(&sig[0..64])
			.map_err(|_| EcdsaVerifyError::BadRS)?;
		let v = secp256k1::RecoveryId::parse(if sig[64] > 26 { sig[64] - 27 } else { sig[64] } as u8)
			.map_err(|_| EcdsaVerifyError::BadV)?;
		let pubkey = secp256k1::recover(&secp256k1::Message::parse(msg), &rs, &v)
			.map_err(|_| EcdsaVerifyError::BadSignature)?;
		Ok(pubkey.serialize_compressed())
	}
}

/// Interface that provides functions for hashing with different algorithms.
#[runtime_interface]
pub trait Hashing {
	/// Conduct a 256-bit Keccak hash.
	fn keccak_256(data: &[u8]) -> [u8; 32] {
		sp_core::hashing::keccak_256(data)
	}

	/// Conduct a 512-bit Keccak hash.
	fn keccak_512(data: &[u8]) -> [u8; 64] {
		sp_core::hashing::keccak_512(data)
	}

	/// Conduct a 256-bit Sha2 hash.
	fn sha2_256(data: &[u8]) -> [u8; 32] {
		sp_core::hashing::sha2_256(data)
	}

	/// Conduct a 128-bit Blake2 hash.
	fn blake2_128(data: &[u8]) -> [u8; 16] {
		sp_core::hashing::blake2_128(data)
	}

	/// Conduct a 256-bit Blake2 hash.
	fn blake2_256(data: &[u8]) -> [u8; 32] {
		sp_core::hashing::blake2_256(data)
	}

	/// Conduct four XX hashes to give a 256-bit result.
	fn twox_256(data: &[u8]) -> [u8; 32] {
		sp_core::hashing::twox_256(data)
	}

	/// Conduct two XX hashes to give a 128-bit result.
	fn twox_128(data: &[u8]) -> [u8; 16] {
		sp_core::hashing::twox_128(data)
	}

	/// Conduct two XX hashes to give a 64-bit result.
	fn twox_64(data: &[u8]) -> [u8; 8] {
		sp_core::hashing::twox_64(data)
	}
}

/// Interface that provides transaction indexing API.
#[runtime_interface]
pub trait TransactionIndex {
	/// Add transaction index. Returns indexed content hash.
	fn index(&mut self, extrinsic: u32, size: u32, context_hash: [u8; 32]) {
		self.storage_index_transaction(extrinsic, &context_hash, size);
	}

	/// Conduct a 512-bit Keccak hash.
	fn renew(&mut self, extrinsic: u32, context_hash: [u8; 32]) {
		self.storage_renew_transaction_index(extrinsic, &context_hash);
	}
}

/// Interface that provides functions to access the Offchain DB.
#[runtime_interface]
pub trait OffchainIndex {
	/// Write a key value pair to the Offchain DB database in a buffered fashion.
	fn set(&mut self, key: &[u8], value: &[u8]) {
		self.set_offchain_storage(key, Some(value));
	}

	/// Remove a key and its associated value from the Offchain DB.
	fn clear(&mut self, key: &[u8]) {
		self.set_offchain_storage(key, None);
	}
}

#[cfg(feature = "std")]
sp_externalities::decl_extension! {
	/// Batch verification extension to register/retrieve from the externalities.
	pub struct VerificationExt(BatchVerifier);
}

/// Interface that provides functions to access the offchain functionality.
///
/// These functions are being made available to the runtime and are called by the runtime.
#[runtime_interface]
pub trait Offchain {
	/// Returns if the local node is a potential validator.
	///
	/// Even if this function returns `true`, it does not mean that any keys are configured
	/// and that the validator is registered in the chain.
	fn is_validator(&mut self) -> bool {
		self.extension::<OffchainWorkerExt>()
			.expect("is_validator can be called only in the offchain worker context")
			.is_validator()
	}

	/// Submit an encoded transaction to the pool.
	///
	/// The transaction will end up in the pool.
	fn submit_transaction(&mut self, data: Vec<u8>) -> Result<(), ()> {
		self.extension::<TransactionPoolExt>()
			.expect("submit_transaction can be called only in the offchain call context with
				TransactionPool capabilities enabled")
			.submit_transaction(data)
	}

	/// Returns information about the local node's network state.
	fn network_state(&mut self) -> Result<OpaqueNetworkState, ()> {
		self.extension::<OffchainWorkerExt>()
			.expect("network_state can be called only in the offchain worker context")
			.network_state()
	}

	/// Returns current UNIX timestamp (in millis)
	fn timestamp(&mut self) -> Timestamp {
		self.extension::<OffchainWorkerExt>()
			.expect("timestamp can be called only in the offchain worker context")
			.timestamp()
	}

	/// Pause the execution until `deadline` is reached.
	fn sleep_until(&mut self, deadline: Timestamp) {
		self.extension::<OffchainWorkerExt>()
			.expect("sleep_until can be called only in the offchain worker context")
			.sleep_until(deadline)
	}

	/// Returns a random seed.
	///
	/// This is a truly random, non-deterministic seed generated by host environment.
	/// Obviously fine in the off-chain worker context.
	fn random_seed(&mut self) -> [u8; 32] {
		self.extension::<OffchainWorkerExt>()
			.expect("random_seed can be called only in the offchain worker context")
			.random_seed()
	}

	/// Sets a value in the local storage.
	///
	/// Note this storage is not part of the consensus, it's only accessible by
	/// offchain worker tasks running on the same machine. It IS persisted between runs.
	fn local_storage_set(&mut self, kind: StorageKind, key: &[u8], value: &[u8]) {
		self.extension::<OffchainDbExt>()
			.expect("local_storage_set can be called only in the offchain call context with
				OffchainDb extension")
			.local_storage_set(kind, key, value)
	}

	/// Remove a value from the local storage.
	///
	/// Note this storage is not part of the consensus, it's only accessible by
	/// offchain worker tasks running on the same machine. It IS persisted between runs.
	fn local_storage_clear(&mut self, kind: StorageKind, key: &[u8]) {
		self.extension::<OffchainDbExt>()
			.expect("local_storage_clear can be called only in the offchain call context with
				OffchainDb extension")
			.local_storage_clear(kind, key)
	}

	/// Sets a value in the local storage if it matches current value.
	///
	/// Since multiple offchain workers may be running concurrently, to prevent
	/// data races use CAS to coordinate between them.
	///
	/// Returns `true` if the value has been set, `false` otherwise.
	///
	/// Note this storage is not part of the consensus, it's only accessible by
	/// offchain worker tasks running on the same machine. It IS persisted between runs.
	fn local_storage_compare_and_set(
		&mut self,
		kind: StorageKind,
		key: &[u8],
		old_value: Option<Vec<u8>>,
		new_value: &[u8],
	) -> bool {
		self.extension::<OffchainDbExt>()
			.expect("local_storage_compare_and_set can be called only in the offchain call context
				with OffchainDb extension")
			.local_storage_compare_and_set(
				kind,
				key,
				old_value.as_ref().map(|v| v.deref()),
				new_value,
			)
	}

	/// Gets a value from the local storage.
	///
	/// If the value does not exist in the storage `None` will be returned.
	/// Note this storage is not part of the consensus, it's only accessible by
	/// offchain worker tasks running on the same machine. It IS persisted between runs.
	fn local_storage_get(&mut self, kind: StorageKind, key: &[u8]) -> Option<Vec<u8>> {
		self.extension::<OffchainDbExt>()
			.expect("local_storage_get can be called only in the offchain call context with
				OffchainDb extension")
			.local_storage_get(kind, key)
	}

	/// Initiates a http request given HTTP verb and the URL.
	///
	/// Meta is a future-reserved field containing additional, parity-scale-codec encoded parameters.
	/// Returns the id of newly started request.
	fn http_request_start(