Rename folder: primitives/sr-primitives -> primitives/runtime (#4280)

* primitives/sr-primitives -> primitives/runtime

* update

substrate/primitives/runtime/src/curve.rs

@@ -0,0 +1,166 @@
+// Copyright 2019 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/>.
+
+//! Provides some utilities to define a piecewise linear function.
+
+use crate::{Perbill, traits::{SimpleArithmetic, SaturatedConversion}};
+use core::ops::Sub;
+
+/// Piecewise Linear function in [0, 1] -> [0, 1].
+#[derive(PartialEq, Eq, primitives::RuntimeDebug)]
+pub struct PiecewiseLinear<'a> {
+	/// Array of points. Must be in order from the lowest abscissas to the highest.
+	pub points: &'a [(Perbill, Perbill)],
+	/// The maximum value that can be returned.
+	pub maximum: Perbill,
+}
+
+fn abs_sub<N: Ord + Sub<Output=N> + Clone>(a: N, b: N) -> N where {
+	a.clone().max(b.clone()) - a.min(b)
+}
+
+impl<'a> PiecewiseLinear<'a> {
+	/// Compute `f(n/d)*d` with `n <= d`. This is useful to avoid loss of precision.
+	pub fn calculate_for_fraction_times_denominator<N>(&self, n: N, d: N) -> N where
+		N: SimpleArithmetic + Clone
+	{
+		let n = n.min(d.clone());
+
+		if self.points.len() == 0 {
+			return N::zero()
+		}
+
+		let next_point_index = self.points.iter()
+			.position(|p| n < p.0 * d.clone());
+
+		let (prev, next) = if let Some(next_point_index) = next_point_index {
+			if let Some(previous_point_index) = next_point_index.checked_sub(1) {
+				(self.points[previous_point_index], self.points[next_point_index])
+			} else {
+				// There is no previous points, take first point ordinate
+				return self.points.first().map(|p| p.1).unwrap_or_else(Perbill::zero) * d
+			}
+		} else {
+			// There is no next points, take last point ordinate
+			return self.points.last().map(|p| p.1).unwrap_or_else(Perbill::zero) * d
+		};
+
+		let delta_y = multiply_by_rational_saturating(
+			abs_sub(n.clone(), prev.0 * d.clone()),
+			abs_sub(next.1.deconstruct(), prev.1.deconstruct()),
+			// Must not saturate as prev abscissa > next abscissa
+			next.0.deconstruct().saturating_sub(prev.0.deconstruct()),
+		);
+
+		// If both substration are same sign then result is positive
+		if (n > prev.0 * d.clone()) == (next.1.deconstruct() > prev.1.deconstruct()) {
+			(prev.1 * d).saturating_add(delta_y)
+		// Otherwise result is negative
+		} else {
+			(prev.1 * d).saturating_sub(delta_y)
+		}
+	}
+}
+
+// Compute value * p / q.
+// This is guaranteed not to overflow on whatever values nor lose precision.
+// `q` must be superior to zero.
+fn multiply_by_rational_saturating<N>(value: N, p: u32, q: u32) -> N
+	where N: SimpleArithmetic + Clone
+{
+	let q = q.max(1);
+
+	// Mul can saturate if p > q
+	let result_divisor_part = (value.clone() / q.into()).saturating_mul(p.into());
+
+	let result_remainder_part = {
+		let rem = value % q.into();
+
+		// Fits into u32 because q is u32 and remainder < q
+		let rem_u32 = rem.saturated_into::<u32>();
+
+		// Multiplication fits into u64 as both term are u32
+		let rem_part = rem_u32 as u64 * p as u64 / q as u64;
+
+		// Can saturate if p > q
+		rem_part.saturated_into::<N>()
+	};
+
+	// Can saturate if p > q
+	result_divisor_part.saturating_add(result_remainder_part)
+}
+
+#[test]
+fn test_multiply_by_rational_saturating() {
+	use std::convert::TryInto;
+
+	let div = 100u32;
+	for value in 0..=div {
+		for p in 0..=div {
+			for q in 1..=div {
+				let value: u64 = (value as u128 * u64::max_value() as u128 / div as u128)
+					.try_into().unwrap();
+				let p = (p as u64 * u32::max_value() as u64 / div as u64)
+					.try_into().unwrap();
+				let q = (q as u64 * u32::max_value() as u64 / div as u64)
+					.try_into().unwrap();
+
+				assert_eq!(
+					multiply_by_rational_saturating(value, p, q),
+					(value as u128 * p as u128 / q as u128)
+						.try_into().unwrap_or(u64::max_value())
+				);
+			}
+		}
+	}
+}
+
+#[test]
+fn test_calculate_for_fraction_times_denominator() {
+	use std::convert::TryInto;
+
+	let curve = PiecewiseLinear {
+		points: &[
+			(Perbill::from_parts(0_000_000_000), Perbill::from_parts(0_500_000_000)),
+			(Perbill::from_parts(0_500_000_000), Perbill::from_parts(1_000_000_000)),
+			(Perbill::from_parts(1_000_000_000), Perbill::from_parts(0_000_000_000)),
+		],
+		maximum: Perbill::from_parts(1_000_000_000),
+	};
+
+	pub fn formal_calculate_for_fraction_times_denominator(n: u64, d: u64) -> u64 {
+		if n <= Perbill::from_parts(0_500_000_000) * d.clone() {
+			n + d / 2
+		} else {
+			(d as u128 * 2 - n as u128 * 2).try_into().unwrap()
+		}
+	}
+
+	let div = 100u32;
+	for d in 0..=div {
+		for n in 0..=d {
+			let d: u64 = (d as u128 * u64::max_value() as u128 / div as u128)
+				.try_into().unwrap();
+			let n: u64 = (n as u128 * u64::max_value() as u128 / div as u128)
+				.try_into().unwrap();
+
+			let res = curve.calculate_for_fraction_times_denominator(n, d);
+			let expected = formal_calculate_for_fraction_times_denominator(n, d);
+
+			assert!(abs_sub(res, expected) <= 1);
+		}
+	}
+}

substrate/primitives/runtime/src/generic/block.rs

@@ -0,0 +1,112 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of a block and associated items.
+
+#[cfg(feature = "std")]
+use std::fmt;
+
+#[cfg(feature = "std")]
+use serde::{Deserialize, Serialize};
+
+use rstd::prelude::*;
+use primitives::RuntimeDebug;
+use crate::codec::{Codec, Encode, Decode};
+use crate::traits::{self, Member, Block as BlockT, Header as HeaderT, MaybeSerialize};
+use crate::Justification;
+
+/// Something to identify a block.
+#[derive(PartialEq, Eq, Clone, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize))]
+#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
+#[cfg_attr(feature = "std", serde(deny_unknown_fields))]
+pub enum BlockId<Block: BlockT> {
+	/// Identify by block header hash.
+	Hash(<<Block as BlockT>::Header as HeaderT>::Hash),
+	/// Identify by block number.
+	Number(<<Block as BlockT>::Header as HeaderT>::Number),
+}
+
+impl<Block: BlockT> BlockId<Block> {
+	/// Create a block ID from a hash.
+	pub fn hash(hash: Block::Hash) -> Self {
+		BlockId::Hash(hash)
+	}
+
+	/// Create a block ID from a number.
+	pub fn number(number: <Block::Header as HeaderT>::Number) -> Self {
+		BlockId::Number(number)
+	}
+}
+
+impl<Block: BlockT> Copy for BlockId<Block> {}
+
+#[cfg(feature = "std")]
+impl<Block: BlockT> fmt::Display for BlockId<Block> {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write!(f, "{:?}", self)
+	}
+}
+
+/// Abstraction over a substrate block.
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
+#[cfg_attr(feature = "std", serde(deny_unknown_fields))]
+pub struct Block<Header, Extrinsic: MaybeSerialize> {
+	/// The block header.
+	pub header: Header,
+	/// The accompanying extrinsics.
+	pub extrinsics: Vec<Extrinsic>,
+}
+
+impl<Header, Extrinsic: MaybeSerialize> traits::Block for Block<Header, Extrinsic>
+where
+	Header: HeaderT,
+	Extrinsic: Member + Codec + traits::Extrinsic,
+{
+	type Extrinsic = Extrinsic;
+	type Header = Header;
+	type Hash = <Self::Header as traits::Header>::Hash;
+
+	fn header(&self) -> &Self::Header {
+		&self.header
+	}
+	fn extrinsics(&self) -> &[Self::Extrinsic] {
+		&self.extrinsics[..]
+	}
+	fn deconstruct(self) -> (Self::Header, Vec<Self::Extrinsic>) {
+		(self.header, self.extrinsics)
+	}
+	fn new(header: Self::Header, extrinsics: Vec<Self::Extrinsic>) -> Self {
+		Block { header, extrinsics }
+	}
+	fn encode_from(header: &Self::Header, extrinsics: &[Self::Extrinsic]) -> Vec<u8> {
+		(header, extrinsics).encode()
+	}
+}
+
+/// Abstraction over a substrate block and justification.
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
+#[cfg_attr(feature = "std", serde(deny_unknown_fields))]
+pub struct SignedBlock<Block> {
+	/// Full block.
+	pub block: Block,
+	/// Block justification.
+	pub justification: Option<Justification>,
+}

substrate/primitives/runtime/src/generic/checked_extrinsic.rs

@@ -0,0 +1,90 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of an extrinsic that has passed the verification
+//! stage.
+
+use crate::traits::{
+	self, Member, MaybeDisplay, SignedExtension, Dispatchable,
+};
+#[allow(deprecated)]
+use crate::traits::ValidateUnsigned;
+use crate::transaction_validity::TransactionValidity;
+
+/// Definition of something that the external world might want to say; its
+/// existence implies that it has been checked and is good, particularly with
+/// regards to the signature.
+#[derive(PartialEq, Eq, Clone, primitives::RuntimeDebug)]
+pub struct CheckedExtrinsic<AccountId, Call, Extra> {
+	/// Who this purports to be from and the number of extrinsics have come before
+	/// from the same signer, if anyone (note this is not a signature).
+	pub signed: Option<(AccountId, Extra)>,
+
+	/// The function that should be called.
+	pub function: Call,
+}
+
+impl<AccountId, Call, Extra, Origin, Info> traits::Applyable for
+	CheckedExtrinsic<AccountId, Call, Extra>
+where
+	AccountId: Member + MaybeDisplay,
+	Call: Member + Dispatchable<Origin=Origin>,
+	Extra: SignedExtension<AccountId=AccountId, Call=Call, DispatchInfo=Info>,
+	Origin: From<Option<AccountId>>,
+	Info: Clone,
+{
+	type AccountId = AccountId;
+	type Call = Call;
+	type DispatchInfo = Info;
+
+	fn sender(&self) -> Option<&Self::AccountId> {
+		self.signed.as_ref().map(|x| &x.0)
+	}
+
+	#[allow(deprecated)] // Allow ValidateUnsigned
+	fn validate<U: ValidateUnsigned<Call = Self::Call>>(
+		&self,
+		info: Self::DispatchInfo,
+		len: usize,
+	) -> TransactionValidity {
+		if let Some((ref id, ref extra)) = self.signed {
+			Extra::validate(extra, id, &self.function, info.clone(), len)
+		} else {
+			let valid = Extra::validate_unsigned(&self.function, info, len)?;
+			let unsigned_validation = U::validate_unsigned(&self.function)?;
+			Ok(valid.combine_with(unsigned_validation))
+		}
+	}
+
+	#[allow(deprecated)] // Allow ValidateUnsigned
+	fn apply<U: ValidateUnsigned<Call=Self::Call>>(
+		self,
+		info: Self::DispatchInfo,
+		len: usize,
+	) -> crate::ApplyExtrinsicResult {
+		let (maybe_who, pre) = if let Some((id, extra)) = self.signed {
+			let pre = Extra::pre_dispatch(extra, &id, &self.function, info.clone(), len)?;
+			(Some(id), pre)
+		} else {
+			let pre = Extra::pre_dispatch_unsigned(&self.function, info.clone(), len)?;
+			U::pre_dispatch(&self.function)?;
+			(None, pre)
+		};
+		let res = self.function.dispatch(Origin::from(maybe_who));
+		Extra::post_dispatch(pre, info.clone(), len);
+		Ok(res.map_err(Into::into))
+	}
+}

substrate/primitives/runtime/src/generic/digest.rs

@@ -0,0 +1,376 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of a digest.
+
+#[cfg(feature = "std")]
+use serde::{Deserialize, Serialize};
+
+use rstd::prelude::*;
+
+use crate::ConsensusEngineId;
+use crate::codec::{Decode, Encode, Input, Error};
+use primitives::RuntimeDebug;
+
+/// Generic header digest.
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct Digest<Hash: Encode + Decode> {
+	/// A list of logs in the digest.
+	pub logs: Vec<DigestItem<Hash>>,
+}
+
+impl<Item: Encode + Decode> Default for Digest<Item> {
+	fn default() -> Self {
+		Digest { logs: Vec::new(), }
+	}
+}
+
+impl<Hash: Encode + Decode> Digest<Hash> {
+	/// Get reference to all digest items.
+	pub fn logs(&self) -> &[DigestItem<Hash>] {
+		&self.logs
+	}
+
+	/// Push new digest item.
+	pub fn push(&mut self, item: DigestItem<Hash>) {
+		self.logs.push(item);
+	}
+
+	/// Pop a digest item.
+	pub fn pop(&mut self) -> Option<DigestItem<Hash>> {
+		self.logs.pop()
+	}
+
+	/// Get reference to the first digest item that matches the passed predicate.
+	pub fn log<T: ?Sized, F: Fn(&DigestItem<Hash>) -> Option<&T>>(&self, predicate: F) -> Option<&T> {
+		self.logs().iter()
+			.filter_map(predicate)
+			.next()
+	}
+
+	/// Get a conversion of the first digest item that successfully converts using the function.
+	pub fn convert_first<T, F: Fn(&DigestItem<Hash>) -> Option<T>>(&self, predicate: F) -> Option<T> {
+		self.logs().iter()
+			.filter_map(predicate)
+			.next()
+	}
+}
+
+
+/// Digest item that is able to encode/decode 'system' digest items and
+/// provide opaque access to other items.
+#[derive(PartialEq, Eq, Clone, RuntimeDebug)]
+pub enum DigestItem<Hash> {
+	/// System digest item that contains the root of changes trie at given
+	/// block. It is created for every block iff runtime supports changes
+	/// trie creation.
+	ChangesTrieRoot(Hash),
+
+	/// A pre-runtime digest.
+	///
+	/// These are messages from the consensus engine to the runtime, although
+	/// the consensus engine can (and should) read them itself to avoid
+	/// code and state duplication. It is erroneous for a runtime to produce
+	/// these, but this is not (yet) checked.
+	PreRuntime(ConsensusEngineId, Vec<u8>),
+
+	/// A message from the runtime to the consensus engine. This should *never*
+	/// be generated by the native code of any consensus engine, but this is not
+	/// checked (yet).
+	Consensus(ConsensusEngineId, Vec<u8>),
+
+	/// Put a Seal on it. This is only used by native code, and is never seen
+	/// by runtimes.
+	Seal(ConsensusEngineId, Vec<u8>),
+
+	/// Some other thing. Unsupported and experimental.
+	Other(Vec<u8>),
+}
+
+#[cfg(feature = "std")]
+impl<Hash: Encode> serde::Serialize for DigestItem<Hash> {
+	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: serde::Serializer {
+		self.using_encoded(|bytes| {
+			primitives::bytes::serialize(bytes, seq)
+		})
+	}
+}
+
+#[cfg(feature = "std")]
+impl<'a, Hash: Decode> serde::Deserialize<'a> for DigestItem<Hash> {
+	fn deserialize<D>(de: D) -> Result<Self, D::Error> where
+		D: serde::Deserializer<'a>,
+	{
+		let r = primitives::bytes::deserialize(de)?;
+		Decode::decode(&mut &r[..])
+			.map_err(|e| serde::de::Error::custom(format!("Decode error: {}", e)))
+	}
+}
+
+/// A 'referencing view' for digest item. Does not own its contents. Used by
+/// final runtime implementations for encoding/decoding its log items.
+#[derive(PartialEq, Eq, Clone, RuntimeDebug)]
+pub enum DigestItemRef<'a, Hash: 'a> {
+	/// Reference to `DigestItem::ChangesTrieRoot`.
+	ChangesTrieRoot(&'a Hash),
+	/// A pre-runtime digest.
+	///
+	/// These are messages from the consensus engine to the runtime, although
+	/// the consensus engine can (and should) read them itself to avoid
+	/// code and state duplication.  It is erroneous for a runtime to produce
+	/// these, but this is not (yet) checked.
+	PreRuntime(&'a ConsensusEngineId, &'a Vec<u8>),
+	/// A message from the runtime to the consensus engine. This should *never*
+	/// be generated by the native code of any consensus engine, but this is not
+	/// checked (yet).
+	Consensus(&'a ConsensusEngineId, &'a Vec<u8>),
+	/// Put a Seal on it. This is only used by native code, and is never seen
+	/// by runtimes.
+	Seal(&'a ConsensusEngineId, &'a Vec<u8>),
+	/// Any 'non-system' digest item, opaque to the native code.
+	Other(&'a Vec<u8>),
+}
+
+/// Type of the digest item. Used to gain explicit control over `DigestItem` encoding
+/// process. We need an explicit control, because final runtimes are encoding their own
+/// digest items using `DigestItemRef` type and we can't auto-derive `Decode`
+/// trait for `DigestItemRef`.
+#[repr(u32)]
+#[derive(Encode, Decode)]
+pub enum DigestItemType {
+	ChangesTrieRoot = 2,
+	PreRuntime = 6,
+	Consensus = 4,
+	Seal = 5,
+	Other = 0,
+}
+
+/// Type of a digest item that contains raw data; this also names the consensus engine ID where
+/// applicable. Used to identify one or more digest items of interest.
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum OpaqueDigestItemId<'a> {
+	/// Type corresponding to DigestItem::PreRuntime.
+	PreRuntime(&'a ConsensusEngineId),
+	/// Type corresponding to DigestItem::Consensus.
+	Consensus(&'a ConsensusEngineId),
+	/// Type corresponding to DigestItem::Seal.
+	Seal(&'a ConsensusEngineId),
+	/// Some other (non-prescribed) type.
+	Other,
+}
+
+impl<Hash> DigestItem<Hash> {
+	/// Returns a 'referencing view' for this digest item.
+	pub fn dref<'a>(&'a self) -> DigestItemRef<'a, Hash> {
+		match *self {
+			DigestItem::ChangesTrieRoot(ref v) => DigestItemRef::ChangesTrieRoot(v),
+			DigestItem::PreRuntime(ref v, ref s) => DigestItemRef::PreRuntime(v, s),
+			DigestItem::Consensus(ref v, ref s) => DigestItemRef::Consensus(v, s),
+			DigestItem::Seal(ref v, ref s) => DigestItemRef::Seal(v, s),
+			DigestItem::Other(ref v) => DigestItemRef::Other(v),
+		}
+	}
+
+	/// Returns `Some` if the entry is the `ChangesTrieRoot` entry.
+	pub fn as_changes_trie_root(&self) -> Option<&Hash> {
+		self.dref().as_changes_trie_root()
+	}
+
+	/// Returns `Some` if this entry is the `PreRuntime` entry.
+	pub fn as_pre_runtime(&self) -> Option<(ConsensusEngineId, &[u8])> {
+		self.dref().as_pre_runtime()
+	}
+
+	/// Returns `Some` if this entry is the `Consensus` entry.
+	pub fn as_consensus(&self) -> Option<(ConsensusEngineId, &[u8])> {
+		self.dref().as_consensus()
+	}
+
+	/// Returns `Some` if this entry is the `Seal` entry.
+	pub fn as_seal(&self) -> Option<(ConsensusEngineId, &[u8])> {
+		self.dref().as_seal()
+	}
+
+	/// Returns Some if `self` is a `DigestItem::Other`.
+	pub fn as_other(&self) -> Option<&[u8]> {
+		match *self {
+			DigestItem::Other(ref v) => Some(&v[..]),
+			_ => None,
+		}
+	}
+
+	/// Returns the opaque data contained in the item if `Some` if this entry has the id given.
+	pub fn try_as_raw(&self, id: OpaqueDigestItemId) -> Option<&[u8]> {
+		self.dref().try_as_raw(id)
+	}
+
+	/// Returns the data contained in the item if `Some` if this entry has the id given, decoded
+	/// to the type provided `T`.
+	pub fn try_to<T: Decode>(&self, id: OpaqueDigestItemId) -> Option<T> {
+		self.dref().try_to::<T>(id)
+	}
+}
+
+impl<Hash: Encode> Encode for DigestItem<Hash> {
+	fn encode(&self) -> Vec<u8> {
+		self.dref().encode()
+	}
+}
+
+impl<Hash: Encode> codec::EncodeLike for DigestItem<Hash> {}
+
+impl<Hash: Decode> Decode for DigestItem<Hash> {
+	#[allow(deprecated)]
+	fn decode<I: Input>(input: &mut I) -> Result<Self, Error> {
+		let item_type: DigestItemType = Decode::decode(input)?;
+		match item_type {
+			DigestItemType::ChangesTrieRoot => Ok(DigestItem::ChangesTrieRoot(
+				Decode::decode(input)?,
+			)),
+			DigestItemType::PreRuntime => {
+				let vals: (ConsensusEngineId, Vec<u8>) = Decode::decode(input)?;
+				Ok(DigestItem::PreRuntime(vals.0, vals.1))
+			},
+			DigestItemType::Consensus => {
+				let vals: (ConsensusEngineId, Vec<u8>) = Decode::decode(input)?;
+				Ok(DigestItem::Consensus(vals.0, vals.1))
+			}
+			DigestItemType::Seal => {
+				let vals: (ConsensusEngineId, Vec<u8>) = Decode::decode(input)?;
+				Ok(DigestItem::Seal(vals.0, vals.1))
+			},
+			DigestItemType::Other => Ok(DigestItem::Other(
+				Decode::decode(input)?,
+			)),
+		}
+	}
+}
+
+impl<'a, Hash> DigestItemRef<'a, Hash> {
+	/// Cast this digest item into `ChangesTrieRoot`.
+	pub fn as_changes_trie_root(&self) -> Option<&'a Hash> {
+		match *self {
+			DigestItemRef::ChangesTrieRoot(ref changes_trie_root) => Some(changes_trie_root),
+			_ => None,
+		}
+	}
+
+	/// Cast this digest item into `PreRuntime`
+	pub fn as_pre_runtime(&self) -> Option<(ConsensusEngineId, &'a [u8])> {
+		match *self {
+			DigestItemRef::PreRuntime(consensus_engine_id, ref data) => Some((*consensus_engine_id, data)),
+			_ => None,
+		}
+	}
+
+	/// Cast this digest item into `Consensus`
+	pub fn as_consensus(&self) -> Option<(ConsensusEngineId, &'a [u8])> {
+		match *self {
+			DigestItemRef::Consensus(consensus_engine_id, ref data) => Some((*consensus_engine_id, data)),
+			_ => None,
+		}
+	}
+
+	/// Cast this digest item into `Seal`
+	pub fn as_seal(&self) -> Option<(ConsensusEngineId, &'a [u8])> {
+		match *self {
+			DigestItemRef::Seal(consensus_engine_id, ref data) => Some((*consensus_engine_id, data)),
+			_ => None,
+		}
+	}
+
+	/// Cast this digest item into `PreRuntime`
+	pub fn as_other(&self) -> Option<&'a [u8]> {
+		match *self {
+			DigestItemRef::Other(ref data) => Some(data),
+			_ => None,
+		}
+	}
+
+	/// Try to match this digest item to the given opaque item identifier; if it matches, then
+	/// return the opaque data it contains.
+	pub fn try_as_raw(&self, id: OpaqueDigestItemId) -> Option<&'a [u8]> {
+		match (id, self) {
+			(OpaqueDigestItemId::Consensus(w), &DigestItemRef::Consensus(v, s)) |
+				(OpaqueDigestItemId::Seal(w), &DigestItemRef::Seal(v, s)) |
+				(OpaqueDigestItemId::PreRuntime(w), &DigestItemRef::PreRuntime(v, s))
+				if v == w => Some(&s[..]),
+			(OpaqueDigestItemId::Other, &DigestItemRef::Other(s)) => Some(&s[..]),
+			_ => None,
+		}
+	}
+
+	/// Try to match this digest item to the given opaque item identifier; if it matches, then
+	/// try to cast to the given datatype; if that works, return it.
+	pub fn try_to<T: Decode>(&self, id: OpaqueDigestItemId) -> Option<T> {
+		self.try_as_raw(id).and_then(|mut x| Decode::decode(&mut x).ok())
+	}
+}
+
+impl<'a, Hash: Encode> Encode for DigestItemRef<'a, Hash> {
+	fn encode(&self) -> Vec<u8> {
+		let mut v = Vec::new();
+
+		match *self {
+			DigestItemRef::ChangesTrieRoot(changes_trie_root) => {
+				DigestItemType::ChangesTrieRoot.encode_to(&mut v);
+				changes_trie_root.encode_to(&mut v);
+			},
+			DigestItemRef::Consensus(val, data) => {
+				DigestItemType::Consensus.encode_to(&mut v);
+				(val, data).encode_to(&mut v);
+			},
+			DigestItemRef::Seal(val, sig) => {
+				DigestItemType::Seal.encode_to(&mut v);
+				(val, sig).encode_to(&mut v);
+			},
+			DigestItemRef::PreRuntime(val, data) => {
+				DigestItemType::PreRuntime.encode_to(&mut v);
+				(val, data).encode_to(&mut v);
+			},
+			DigestItemRef::Other(val) => {
+				DigestItemType::Other.encode_to(&mut v);
+				val.encode_to(&mut v);
+			},
+		}
+
+		v
+	}
+}
+
+impl<'a, Hash: Encode> codec::EncodeLike for DigestItemRef<'a, Hash> {}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn should_serialize_digest() {
+		let digest = Digest {
+			logs: vec![
+				DigestItem::ChangesTrieRoot(4),
+				DigestItem::Other(vec![1, 2, 3]),
+				DigestItem::Seal(*b"test", vec![1, 2, 3])
+			],
+		};
+
+		assert_eq!(
+			::serde_json::to_string(&digest).unwrap(),
+			r#"{"logs":["0x0204000000","0x000c010203","0x05746573740c010203"]}"#
+		);
+	}
+}

substrate/primitives/runtime/src/generic/era.rs

@@ -0,0 +1,206 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of an unchecked (pre-verification) extrinsic.
+
+#[cfg(feature = "std")]
+use serde::{Serialize, Deserialize};
+
+use crate::codec::{Decode, Encode, Input, Output, Error};
+
+/// Era period
+pub type Period = u64;
+
+/// Era phase
+pub type Phase = u64;
+
+/// An era to describe the longevity of a transaction.
+#[derive(PartialEq, Eq, Clone, Copy, primitives::RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub enum Era {
+	/// The transaction is valid forever. The genesis hash must be present in the signed content.
+	Immortal,
+
+	/// Period and phase are encoded:
+	/// - The period of validity from the block hash found in the signing material.
+	/// - The phase in the period that this transaction's lifetime begins (and, importantly,
+	/// implies which block hash is included in the signature material). If the `period` is
+	/// greater than 1 << 12, then it will be a factor of the times greater than 1<<12 that
+	/// `period` is.
+	Mortal(Period, Phase),
+}
+
+/*
+E.g. with period == 4:
+0         10        20        30        40
+0123456789012345678901234567890123456789012
+             |...|
+   authored -/   \- expiry
+phase = 1
+n = Q(current - phase, period) + phase
+*/
+impl Era {
+	/// Create a new era based on a period (which should be a power of two between 4 and 65536 inclusive)
+	/// and a block number on which it should start (or, for long periods, be shortly after the start).
+	pub fn mortal(period: u64, current: u64) -> Self {
+		let period = period.checked_next_power_of_two()
+			.unwrap_or(1 << 16)
+			.max(4)
+			.min(1 << 16);
+		let phase = current % period;
+		let quantize_factor = (period >> 12).max(1);
+		let quantized_phase = phase / quantize_factor * quantize_factor;
+
+		Era::Mortal(period, quantized_phase)
+	}
+
+	/// Create an "immortal" transaction.
+	pub fn immortal() -> Self {
+		Era::Immortal
+	}
+
+	/// `true` if this is an immortal transaction.
+	pub fn is_immortal(&self) -> bool {
+		match self {
+			Era::Immortal => true,
+			_ => false,
+		}
+	}
+
+	/// Get the block number of the start of the era whose properties this object
+	/// describes that `current` belongs to.
+	pub fn birth(self, current: u64) -> u64 {
+		match self {
+			Era::Immortal => 0,
+			Era::Mortal(period, phase) => (current.max(phase) - phase) / period * period + phase,
+		}
+	}
+
+	/// Get the block number of the first block at which the era has ended.
+	pub fn death(self, current: u64) -> u64 {
+		match self {
+			Era::Immortal => u64::max_value(),
+			Era::Mortal(period, _) => self.birth(current) + period,
+		}
+	}
+}
+
+impl Encode for Era {
+	fn encode_to<T: Output>(&self, output: &mut T) {
+		match self {
+			Era::Immortal => output.push_byte(0),
+			Era::Mortal(period, phase) => {
+				let quantize_factor = (*period as u64 >> 12).max(1);
+				let encoded = (period.trailing_zeros() - 1).max(1).min(15) as u16 | ((phase / quantize_factor) << 4) as u16;
+				output.push(&encoded);
+			}
+		}
+	}
+}
+
+impl codec::EncodeLike for Era {}
+
+impl Decode for Era {
+	fn decode<I: Input>(input: &mut I) -> Result<Self, Error> {
+		let first = input.read_byte()?;
+		if first == 0 {
+			Ok(Era::Immortal)
+		} else {
+			let encoded = first as u64 + ((input.read_byte()? as u64) << 8);
+			let period = 2 << (encoded % (1 << 4));
+			let quantize_factor = (period >> 12).max(1);
+			let phase = (encoded >> 4) * quantize_factor;
+			if period >= 4 && phase < period {
+				Ok(Era::Mortal(period, phase))
+			} else {
+				Err("Invalid period and phase".into())
+			}
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn immortal_works() {
+		let e = Era::immortal();
+		assert_eq!(e.birth(0), 0);
+		assert_eq!(e.death(0), u64::max_value());
+		assert_eq!(e.birth(1), 0);
+		assert_eq!(e.death(1), u64::max_value());
+		assert_eq!(e.birth(u64::max_value()), 0);
+		assert_eq!(e.death(u64::max_value()), u64::max_value());
+		assert!(e.is_immortal());
+
+		assert_eq!(e.encode(), vec![0u8]);
+		assert_eq!(e, Era::decode(&mut&[0u8][..]).unwrap());
+	}
+
+	#[test]
+	fn mortal_codec_works() {
+		let e = Era::mortal(64, 42);
+		assert!(!e.is_immortal());
+
+		let expected = vec![5 + 42 % 16 * 16, 42 / 16];
+		assert_eq!(e.encode(), expected);
+		assert_eq!(e, Era::decode(&mut&expected[..]).unwrap());
+	}
+
+	#[test]
+	fn long_period_mortal_codec_works() {
+		let e = Era::mortal(32768, 20000);
+
+		let expected = vec![(14 + 2500 % 16 * 16) as u8, (2500 / 16) as u8];
+		assert_eq!(e.encode(), expected);
+		assert_eq!(e, Era::decode(&mut&expected[..]).unwrap());
+	}
+
+	#[test]
+	fn era_initialization_works() {
+		assert_eq!(Era::mortal(64, 42), Era::Mortal(64, 42));
+		assert_eq!(Era::mortal(32768, 20000), Era::Mortal(32768, 20000));
+		assert_eq!(Era::mortal(200, 513), Era::Mortal(256, 1));
+		assert_eq!(Era::mortal(2, 1), Era::Mortal(4, 1));
+		assert_eq!(Era::mortal(4, 5), Era::Mortal(4, 1));
+	}
+
+	#[test]
+	fn quantized_clamped_era_initialization_works() {
+		// clamp 1000000 to 65536, quantize 1000001 % 65536 to the nearest 4
+		assert_eq!(Era::mortal(1000000, 1000001), Era::Mortal(65536, 1000001 % 65536 / 4 * 4));
+	}
+
+	#[test]
+	fn mortal_birth_death_works() {
+		let e = Era::mortal(4, 6);
+		for i in 6..10 {
+			assert_eq!(e.birth(i), 6);
+			assert_eq!(e.death(i), 10);
+		}
+
+		// wrong because it's outside of the (current...current + period) range
+		assert_ne!(e.birth(10), 6);
+		assert_ne!(e.birth(5), 6);
+	}
+
+	#[test]
+	fn current_less_than_phase() {
+		// should not panic
+		Era::mortal(4, 3).birth(1);
+	}
+}

substrate/primitives/runtime/src/generic/header.rs

@@ -0,0 +1,199 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of a block header.
+
+#[cfg(feature = "std")]
+use serde::{Deserialize, Serialize};
+use crate::codec::{Decode, Encode, Codec, Input, Output, HasCompact, EncodeAsRef, Error};
+use crate::traits::{
+	self, Member, SimpleArithmetic, SimpleBitOps, Hash as HashT,
+	MaybeSerializeDeserialize, MaybeSerialize, MaybeDisplay,
+};
+use crate::generic::Digest;
+use primitives::U256;
+use rstd::{
+	convert::TryFrom,
+	fmt::Debug,
+};
+
+/// Abstraction over a block header for a substrate chain.
+#[derive(PartialEq, Eq, Clone, primitives::RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
+#[cfg_attr(feature = "std", serde(deny_unknown_fields))]
+pub struct Header<Number: Copy + Into<U256> + TryFrom<U256>, Hash: HashT> {
+	/// The parent hash.
+	pub parent_hash: Hash::Output,
+	/// The block number.
+	#[cfg_attr(feature = "std", serde(
+		serialize_with = "serialize_number",
+		deserialize_with = "deserialize_number"))]
+	pub number: Number,
+	/// The state trie merkle root
+	pub state_root: Hash::Output,
+	/// The merkle root of the extrinsics.
+	pub extrinsics_root: Hash::Output,
+	/// A chain-specific digest of data useful for light clients or referencing auxiliary data.
+	pub digest: Digest<Hash::Output>,
+}
+
+#[cfg(feature = "std")]
+pub fn serialize_number<S, T: Copy + Into<U256> + TryFrom<U256>>(
+	val: &T, s: S,
+) -> Result<S::Ok, S::Error> where S: serde::Serializer {
+	let u256: U256 = (*val).into();
+	serde::Serialize::serialize(&u256, s)
+}
+
+#[cfg(feature = "std")]
+pub fn deserialize_number<'a, D, T: Copy + Into<U256> + TryFrom<U256>>(
+	d: D,
+) -> Result<T, D::Error> where D: serde::Deserializer<'a> {
+	let u256: U256 = serde::Deserialize::deserialize(d)?;
+	TryFrom::try_from(u256).map_err(|_| serde::de::Error::custom("Try from failed"))
+}
+
+impl<Number, Hash> Decode for Header<Number, Hash> where
+	Number: HasCompact + Copy + Into<U256> + TryFrom<U256>,
+	Hash: HashT,
+	Hash::Output: Decode,
+{
+	fn decode<I: Input>(input: &mut I) -> Result<Self, Error> {
+		Ok(Header {
+			parent_hash: Decode::decode(input)?,
+			number: <<Number as HasCompact>::Type>::decode(input)?.into(),
+			state_root: Decode::decode(input)?,
+			extrinsics_root: Decode::decode(input)?,
+			digest: Decode::decode(input)?,
+		})
+	}
+}
+
+impl<Number, Hash> Encode for Header<Number, Hash> where
+	Number: HasCompact + Copy + Into<U256> + TryFrom<U256>,
+	Hash: HashT,
+	Hash::Output: Encode,
+{
+	fn encode_to<T: Output>(&self, dest: &mut T) {
+		dest.push(&self.parent_hash);
+		dest.push(&<<<Number as HasCompact>::Type as EncodeAsRef<_>>::RefType>::from(&self.number));
+		dest.push(&self.state_root);
+		dest.push(&self.extrinsics_root);
+		dest.push(&self.digest);
+	}
+}
+
+impl<Number, Hash> codec::EncodeLike for Header<Number, Hash> where
+	Number: HasCompact + Copy + Into<U256> + TryFrom<U256>,
+	Hash: HashT,
+	Hash::Output: Encode,
+{}
+
+impl<Number, Hash> traits::Header for Header<Number, Hash> where
+	Number: Member + MaybeSerializeDeserialize + Debug + rstd::hash::Hash + MaybeDisplay +
+		SimpleArithmetic + Codec + Copy + Into<U256> + TryFrom<U256>,
+	Hash: HashT,
+	Hash::Output: Default + rstd::hash::Hash + Copy + Member +
+		MaybeSerialize + Debug + MaybeDisplay + SimpleBitOps + Codec,
+{
+	type Number = Number;
+	type Hash = <Hash as HashT>::Output;
+	type Hashing = Hash;
+
+	fn number(&self) -> &Self::Number { &self.number }
+	fn set_number(&mut self, num: Self::Number) { self.number = num }
+
+	fn extrinsics_root(&self) -> &Self::Hash { &self.extrinsics_root }
+	fn set_extrinsics_root(&mut self, root: Self::Hash) { self.extrinsics_root = root }
+
+	fn state_root(&self) -> &Self::Hash { &self.state_root }
+	fn set_state_root(&mut self, root: Self::Hash) { self.state_root = root }
+
+	fn parent_hash(&self) -> &Self::Hash { &self.parent_hash }
+	fn set_parent_hash(&mut self, hash: Self::Hash) { self.parent_hash = hash }
+
+	fn digest(&self) -> &Digest<Self::Hash> { &self.digest }
+
+	fn digest_mut(&mut self) -> &mut Digest<Self::Hash> {
+		#[cfg(feature = "std")]
+		log::debug!(target: "header", "Retrieving mutable reference to digest");
+		&mut self.digest
+	}
+
+	fn new(
+		number: Self::Number,
+		extrinsics_root: Self::Hash,
+		state_root: Self::Hash,
+		parent_hash: Self::Hash,
+		digest: Digest<Self::Hash>,
+	) -> Self {
+		Header {
+			number,
+			extrinsics_root,
+			state_root,
+			parent_hash,
+			digest,
+		}
+	}
+}
+
+impl<Number, Hash> Header<Number, Hash> where
+	Number: Member + rstd::hash::Hash + Copy + MaybeDisplay + SimpleArithmetic + Codec + Into<U256> + TryFrom<U256>,
+	Hash: HashT,
+	Hash::Output: Default + rstd::hash::Hash + Copy + Member + MaybeDisplay + SimpleBitOps + Codec,
+ {
+	/// Convenience helper for computing the hash of the header without having
+	/// to import the trait.
+	pub fn hash(&self) -> Hash::Output {
+		Hash::hash_of(self)
+	}
+}
+
+#[cfg(all(test, feature = "std"))]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn should_serialize_numbers() {
+		fn serialize(num: u128) -> String {
+			let mut v = vec![];
+			{
+				let mut ser = serde_json::Serializer::new(std::io::Cursor::new(&mut v));
+				serialize_number(&num, &mut ser).unwrap();
+			}
+			String::from_utf8(v).unwrap()
+		}
+
+		assert_eq!(serialize(0), "\"0x0\"".to_owned());
+		assert_eq!(serialize(1), "\"0x1\"".to_owned());
+		assert_eq!(serialize(u64::max_value() as u128), "\"0xffffffffffffffff\"".to_owned());
+		assert_eq!(serialize(u64::max_value() as u128 + 1), "\"0x10000000000000000\"".to_owned());
+	}
+
+	#[test]
+	fn should_deserialize_number() {
+		fn deserialize(num: &str) -> u128 {
+			let mut der = serde_json::Deserializer::new(serde_json::de::StrRead::new(num));
+			deserialize_number(&mut der).unwrap()
+		}
+
+		assert_eq!(deserialize("\"0x0\""), 0);
+		assert_eq!(deserialize("\"0x1\""), 1);
+		assert_eq!(deserialize("\"0xffffffffffffffff\""), u64::max_value() as u128);
+		assert_eq!(deserialize("\"0x10000000000000000\""), u64::max_value() as u128 + 1);
+	}
+}

substrate/primitives/runtime/src/generic/mod.rs

@@ -0,0 +1,62 @@
+// Copyright 2017-2019 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/>.
+
+// tag::description[]
+//! Generic implementations of Extrinsic/Header/Block.
+// end::description[]
+
+mod unchecked_extrinsic;
+mod era;
+mod checked_extrinsic;
+mod header;
+mod block;
+mod digest;
+#[cfg(test)]
+mod tests;
+
+pub use self::unchecked_extrinsic::{UncheckedExtrinsic, SignedPayload};
+pub use self::era::{Era, Phase};
+pub use self::checked_extrinsic::CheckedExtrinsic;
+pub use self::header::Header;
+pub use self::block::{Block, SignedBlock, BlockId};
+pub use self::digest::{
+	Digest, DigestItem, DigestItemRef, OpaqueDigestItemId
+};
+
+use crate::codec::Encode;
+use rstd::prelude::*;
+
+fn encode_with_vec_prefix<T: Encode, F: Fn(&mut Vec<u8>)>(encoder: F) -> Vec<u8> {
+	let size = ::rstd::mem::size_of::<T>();
+	let reserve = match size {
+		0..=0b00111111 => 1,
+		0..=0b00111111_11111111 => 2,
+		_ => 4,
+	};
+	let mut v = Vec::with_capacity(reserve + size);
+	v.resize(reserve, 0);
+	encoder(&mut v);
+
+	// need to prefix with the total length to ensure it's binary compatible with
+	// Vec<u8>.
+	let mut length: Vec<()> = Vec::new();
+	length.resize(v.len() - reserve, ());
+	length.using_encoded(|s| {
+		v.splice(0..reserve, s.iter().cloned());
+	});
+
+	v
+}

substrate/primitives/runtime/src/generic/tests.rs

@@ -0,0 +1,60 @@
+// Copyright 2017-2019 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/>.
+
+//! Tests for the generic implementations of Extrinsic/Header/Block.
+
+use crate::codec::{Decode, Encode};
+use primitives::H256;
+use super::DigestItem;
+
+#[test]
+fn system_digest_item_encoding() {
+	let item = DigestItem::ChangesTrieRoot::<H256>(H256::default());
+	let encoded = item.encode();
+	assert_eq!(encoded, vec![
+		// type = DigestItemType::ChangesTrieRoot
+		2,
+		// trie root
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+		0, 0, 0, 0,
+	]);
+
+	let decoded: DigestItem<H256> = Decode::decode(&mut &encoded[..]).unwrap();
+	assert_eq!(item, decoded);
+}
+
+#[test]
+fn non_system_digest_item_encoding() {
+	let item = DigestItem::Other::<H256>(vec![10, 20, 30]);
+	let encoded = item.encode();
+	assert_eq!(encoded, vec![
+		// type = DigestItemType::Other
+		0,
+		// length of other data
+		12,
+		// authorities
+		10, 20, 30,
+	]);
+
+	let decoded: DigestItem<H256> = Decode::decode(&mut &encoded[..]).unwrap();
+	assert_eq!(item, decoded);
+}

substrate/primitives/runtime/src/generic/unchecked_extrinsic.rs

@@ -0,0 +1,409 @@
+// Copyright 2017-2019 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/>.
+
+//! Generic implementation of an unchecked (pre-verification) extrinsic.
+
+use rstd::{fmt, prelude::*};
+use runtime_io::hashing::blake2_256;
+use codec::{Decode, Encode, EncodeLike, Input, Error};
+use crate::{
+	traits::{self, Member, MaybeDisplay, SignedExtension, Checkable, Extrinsic, IdentifyAccount},
+	generic::CheckedExtrinsic, transaction_validity::{TransactionValidityError, InvalidTransaction},
+};
+
+const TRANSACTION_VERSION: u8 = 4;
+
+/// A extrinsic right from the external world. This is unchecked and so
+/// can contain a signature.
+#[derive(PartialEq, Eq, Clone)]
+pub struct UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Extra: SignedExtension
+{
+	/// The signature, address, number of extrinsics have come before from
+	/// the same signer and an era describing the longevity of this transaction,
+	/// if this is a signed extrinsic.
+	pub signature: Option<(Address, Signature, Extra)>,
+	/// The function that should be called.
+	pub function: Call,
+}
+
+impl<Address, Call, Signature, Extra: SignedExtension>
+	UncheckedExtrinsic<Address, Call, Signature, Extra>
+{
+	/// New instance of a signed extrinsic aka "transaction".
+	pub fn new_signed(
+		function: Call,
+		signed: Address,
+		signature: Signature,
+		extra: Extra
+	) -> Self {
+		UncheckedExtrinsic {
+			signature: Some((signed, signature, extra)),
+			function,
+		}
+	}
+
+	/// New instance of an unsigned extrinsic aka "inherent".
+	pub fn new_unsigned(function: Call) -> Self {
+		UncheckedExtrinsic {
+			signature: None,
+			function,
+		}
+	}
+}
+
+impl<Address, Call, Signature, Extra: SignedExtension> Extrinsic
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+{
+	type Call = Call;
+
+	type SignaturePayload = (
+		Address,
+		Signature,
+		Extra,
+	);
+
+	fn is_signed(&self) -> Option<bool> {
+		Some(self.signature.is_some())
+	}
+
+	fn new(function: Call, signed_data: Option<Self::SignaturePayload>) -> Option<Self> {
+		Some(if let Some((address, signature, extra)) = signed_data {
+			UncheckedExtrinsic::new_signed(function, address, signature, extra)
+		} else {
+			UncheckedExtrinsic::new_unsigned(function)
+		})
+	}
+}
+
+impl<Address, AccountId, Call, Signature, Extra, Lookup>
+	Checkable<Lookup>
+for
+	UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Address: Member + MaybeDisplay,
+	Call: Encode + Member,
+	Signature: Member + traits::Verify,
+	<Signature as traits::Verify>::Signer: IdentifyAccount<AccountId=AccountId>,
+	Extra: SignedExtension<AccountId=AccountId>,
+	AccountId: Member + MaybeDisplay,
+	Lookup: traits::Lookup<Source=Address, Target=AccountId>,
+{
+	type Checked = CheckedExtrinsic<AccountId, Call, Extra>;
+
+	fn check(self, lookup: &Lookup) -> Result<Self::Checked, TransactionValidityError> {
+		Ok(match self.signature {
+			Some((signed, signature, extra)) => {
+				let signed = lookup.lookup(signed)?;
+				let raw_payload = SignedPayload::new(self.function, extra)?;
+				if !raw_payload.using_encoded(|payload| {
+					signature.verify(payload, &signed)
+				}) {
+					return Err(InvalidTransaction::BadProof.into())
+				}
+
+				let (function, extra, _) = raw_payload.deconstruct();
+				CheckedExtrinsic {
+					signed: Some((signed, extra)),
+					function,
+				}
+			}
+			None => CheckedExtrinsic {
+				signed: None,
+				function: self.function,
+			},
+		})
+	}
+}
+
+/// A payload that has been signed for an unchecked extrinsics.
+///
+/// Note that the payload that we sign to produce unchecked extrinsic signature
+/// is going to be different than the `SignaturePayload` - so the thing the extrinsic
+/// actually contains.
+pub struct SignedPayload<Call, Extra: SignedExtension>((
+	Call,
+	Extra,
+	Extra::AdditionalSigned,
+));
+
+impl<Call, Extra> SignedPayload<Call, Extra> where
+	Call: Encode,
+	Extra: SignedExtension,
+{
+	/// Create new `SignedPayload`.
+	///
+	/// This function may fail if `additional_signed` of `Extra` is not available.
+	pub fn new(call: Call, extra: Extra) -> Result<Self, TransactionValidityError> {
+		let additional_signed = extra.additional_signed()?;
+		let raw_payload = (call, extra, additional_signed);
+		Ok(Self(raw_payload))
+	}
+
+	/// Create new `SignedPayload` from raw components.
+	pub fn from_raw(call: Call, extra: Extra, additional_signed: Extra::AdditionalSigned) -> Self {
+		Self((call, extra, additional_signed))
+	}
+
+	/// Deconstruct the payload into it's components.
+	pub fn deconstruct(self) -> (Call, Extra, Extra::AdditionalSigned) {
+		self.0
+	}
+}
+
+impl<Call, Extra> Encode for SignedPayload<Call, Extra> where
+	Call: Encode,
+	Extra: SignedExtension,
+{
+	/// Get an encoded version of this payload.
+	///
+	/// Payloads longer than 256 bytes are going to be `blake2_256`-hashed.
+	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+		self.0.using_encoded(|payload| {
+			if payload.len() > 256 {
+				f(&blake2_256(payload)[..])
+			} else {
+				f(payload)
+			}
+		})
+	}
+}
+
+impl<Call, Extra> EncodeLike for SignedPayload<Call, Extra>
+where
+	Call: Encode,
+	Extra: SignedExtension,
+{}
+
+impl<Address, Call, Signature, Extra> Decode
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Address: Decode,
+	Signature: Decode,
+	Call: Decode,
+	Extra: SignedExtension,
+{
+	fn decode<I: Input>(input: &mut I) -> Result<Self, Error> {
+		// This is a little more complicated than usual since the binary format must be compatible
+		// with substrate's generic `Vec<u8>` type. Basically this just means accepting that there
+		// will be a prefix of vector length (we don't need
+		// to use this).
+		let _length_do_not_remove_me_see_above: Vec<()> = Decode::decode(input)?;
+
+		let version = input.read_byte()?;
+
+		let is_signed = version & 0b1000_0000 != 0;
+		let version = version & 0b0111_1111;
+		if version != TRANSACTION_VERSION {
+			return Err("Invalid transaction version".into());
+		}
+
+		Ok(UncheckedExtrinsic {
+			signature: if is_signed { Some(Decode::decode(input)?) } else { None },
+			function: Decode::decode(input)?,
+		})
+	}
+}
+
+impl<Address, Call, Signature, Extra> Encode
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Address: Encode,
+	Signature: Encode,
+	Call: Encode,
+	Extra: SignedExtension,
+{
+	fn encode(&self) -> Vec<u8> {
+		super::encode_with_vec_prefix::<Self, _>(|v| {
+			// 1 byte version id.
+			match self.signature.as_ref() {
+				Some(s) => {
+					v.push(TRANSACTION_VERSION | 0b1000_0000);
+					s.encode_to(v);
+				}
+				None => {
+					v.push(TRANSACTION_VERSION & 0b0111_1111);
+				}
+			}
+			self.function.encode_to(v);
+		})
+	}
+}
+
+impl<Address, Call, Signature, Extra> EncodeLike
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Address: Encode,
+	Signature: Encode,
+	Call: Encode,
+	Extra: SignedExtension,
+{}
+
+#[cfg(feature = "std")]
+impl<Address: Encode, Signature: Encode, Call: Encode, Extra: SignedExtension> serde::Serialize
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+{
+	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: ::serde::Serializer {
+		self.using_encoded(|bytes| seq.serialize_bytes(bytes))
+	}
+}
+
+impl<Address, Call, Signature, Extra> fmt::Debug
+	for UncheckedExtrinsic<Address, Call, Signature, Extra>
+where
+	Address: fmt::Debug,
+	Call: fmt::Debug,
+	Extra: SignedExtension,
+{
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write!(
+			f,
+			"UncheckedExtrinsic({:?}, {:?})",
+			self.signature.as_ref().map(|x| (&x.0, &x.2)),
+			self.function,
+		)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use runtime_io::hashing::blake2_256;
+	use crate::codec::{Encode, Decode};
+	use crate::traits::{SignedExtension, IdentifyAccount, IdentityLookup};
+	use serde::{Serialize, Deserialize};
+
+	type TestContext = IdentityLookup<u64>;
+
+	#[derive(Eq, PartialEq, Clone, Copy, Debug, Serialize, Deserialize, Encode, Decode)]
+	pub struct TestSigner(pub u64);
+	impl From<u64> for TestSigner { fn from(x: u64) -> Self { Self(x) } }
+	impl From<TestSigner> for u64 { fn from(x: TestSigner) -> Self { x.0 } }
+	impl IdentifyAccount for TestSigner {
+		type AccountId = u64;
+		fn into_account(self) -> u64 { self.into() }
+	}
+
+	#[derive(Eq, PartialEq, Clone, Debug, Serialize, Deserialize, Encode, Decode)]
+	struct TestSig(u64, Vec<u8>);
+	impl traits::Verify for TestSig {
+		type Signer = TestSigner;
+		fn verify<L: traits::Lazy<[u8]>>(&self, mut msg: L, signer: &u64) -> bool {
+			signer == &self.0 && msg.get() == &self.1[..]
+		}
+	}
+
+	type TestAccountId = u64;
+	type TestCall = Vec<u8>;
+
+	const TEST_ACCOUNT: TestAccountId = 0;
+
+	// NOTE: this is demonstration. One can simply use `()` for testing.
+	#[derive(Debug, Encode, Decode, Clone, Eq, PartialEq, Ord, PartialOrd)]
+	struct TestExtra;
+	impl SignedExtension for TestExtra {
+		type AccountId = u64;
+		type Call = ();
+		type AdditionalSigned = ();
+		type DispatchInfo = ();
+		type Pre = ();
+
+		fn additional_signed(&self) -> rstd::result::Result<(), TransactionValidityError> { Ok(()) }
+	}
+
+	type Ex = UncheckedExtrinsic<TestAccountId, TestCall, TestSig, TestExtra>;
+	type CEx = CheckedExtrinsic<TestAccountId, TestCall, TestExtra>;
+
+	#[test]
+	fn unsigned_codec_should_work() {
+		let ux = Ex::new_unsigned(vec![0u8; 0]);
+		let encoded = ux.encode();
+		assert_eq!(Ex::decode(&mut &encoded[..]), Ok(ux));
+	}
+
+	#[test]
+	fn signed_codec_should_work() {
+		let ux = Ex::new_signed(
+			vec![0u8; 0],
+			TEST_ACCOUNT,
+			TestSig(TEST_ACCOUNT, (vec![0u8; 0], TestExtra).encode()),
+			TestExtra
+		);
+		let encoded = ux.encode();
+		assert_eq!(Ex::decode(&mut &encoded[..]), Ok(ux));
+	}
+
+	#[test]
+	fn large_signed_codec_should_work() {
+		let ux = Ex::new_signed(
+			vec![0u8; 0],
+			TEST_ACCOUNT,
+			TestSig(TEST_ACCOUNT, (vec![0u8; 257], TestExtra)
+				.using_encoded(blake2_256)[..].to_owned()),
+			TestExtra
+		);
+		let encoded = ux.encode();
+		assert_eq!(Ex::decode(&mut &encoded[..]), Ok(ux));
+	}
+
+	#[test]
+	fn unsigned_check_should_work() {
+		let ux = Ex::new_unsigned(vec![0u8; 0]);
+		assert!(!ux.is_signed().unwrap_or(false));
+		assert!(<Ex as Checkable<TestContext>>::check(ux, &Default::default()).is_ok());
+	}
+
+	#[test]
+	fn badly_signed_check_should_fail() {
+		let ux = Ex::new_signed(
+			vec![0u8; 0],
+			TEST_ACCOUNT,
+			TestSig(TEST_ACCOUNT, vec![0u8; 0]),
+			TestExtra,
+		);
+		assert!(ux.is_signed().unwrap_or(false));
+		assert_eq!(
+			<Ex as Checkable<TestContext>>::check(ux, &Default::default()),
+			Err(InvalidTransaction::BadProof.into()),
+		);
+	}
+
+	#[test]
+	fn signed_check_should_work() {
+		let ux = Ex::new_signed(
+			vec![0u8; 0],
+			TEST_ACCOUNT,
+			TestSig(TEST_ACCOUNT, (vec![0u8; 0], TestExtra).encode()),
+			TestExtra,
+		);
+		assert!(ux.is_signed().unwrap_or(false));
+		assert_eq!(
+			<Ex as Checkable<TestContext>>::check(ux, &Default::default()),
+			Ok(CEx { signed: Some((TEST_ACCOUNT, TestExtra)), function: vec![0u8; 0] }),
+		);
+	}
+
+	#[test]
+	fn encoding_matches_vec() {
+		let ex = Ex::new_unsigned(vec![0u8; 0]);
+		let encoded = ex.encode();
+		let decoded = Ex::decode(&mut encoded.as_slice()).unwrap();
+		assert_eq!(decoded, ex);
+		let as_vec: Vec<u8> = Decode::decode(&mut encoded.as_slice()).unwrap();
+		assert_eq!(as_vec.encode(), encoded);
+	}
+}

substrate/primitives/runtime/src/lib.rs

@@ -0,0 +1,685 @@
+// Copyright 2017-2019 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/>.
+
+//! Runtime Modules shared primitive types.
+
+#![warn(missing_docs)]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+// to allow benchmarking
+#![cfg_attr(feature = "bench", feature(test))]
+#[cfg(feature = "bench")] extern crate test;
+
+#[doc(hidden)]
+pub use codec;
+#[cfg(feature = "std")]
+#[doc(hidden)]
+pub use serde;
+#[doc(hidden)]
+pub use rstd;
+
+#[doc(hidden)]
+pub use paste;
+
+#[doc(hidden)]
+pub use app_crypto;
+
+#[cfg(feature = "std")]
+pub use primitives::storage::{StorageOverlay, ChildrenStorageOverlay};
+
+use rstd::prelude::*;
+use rstd::convert::TryFrom;
+use primitives::{crypto, ed25519, sr25519, ecdsa, hash::{H256, H512}};
+use codec::{Encode, Decode};
+
+pub mod curve;
+pub mod generic;
+pub mod offchain;
+#[cfg(feature = "std")]
+pub mod testing;
+pub mod traits;
+pub mod transaction_validity;
+pub mod random_number_generator;
+
+/// Re-export these since they're only "kind of" generic.
+pub use generic::{DigestItem, Digest};
+
+/// Re-export this since it's part of the API of this crate.
+pub use primitives::{TypeId, crypto::{key_types, KeyTypeId, CryptoType, AccountId32}};
+pub use app_crypto::{RuntimeAppPublic, BoundToRuntimeAppPublic};
+
+/// Re-export `RuntimeDebug`, to avoid dependency clutter.
+pub use primitives::RuntimeDebug;
+
+/// Re-export top-level arithmetic stuff.
+pub use arithmetic::{Perquintill, Perbill, Permill, Percent, Rational128, Fixed64};
+/// Re-export 128 bit helpers.
+pub use arithmetic::helpers_128bit;
+/// Re-export big_uint stuff.
+pub use arithmetic::biguint;
+
+pub use random_number_generator::RandomNumberGenerator;
+
+/// An abstraction over justification for a block's validity under a consensus algorithm.
+///
+/// Essentially a finality proof. The exact formulation will vary between consensus
+/// algorithms. In the case where there are multiple valid proofs, inclusion within
+/// the block itself would allow swapping justifications to change the block's hash
+/// (and thus fork the chain). Sending a `Justification` alongside a block instead
+/// bypasses this problem.
+pub type Justification = Vec<u8>;
+
+use traits::{Verify, Lazy};
+
+/// A module identifier. These are per module and should be stored in a registry somewhere.
+#[derive(Clone, Copy, Eq, PartialEq, Encode, Decode)]
+pub struct ModuleId(pub [u8; 8]);
+
+impl TypeId for ModuleId {
+	const TYPE_ID: [u8; 4] = *b"modl";
+}
+
+/// A String that is a `&'static str` on `no_std` and a `Cow<'static, str>` on `std`.
+#[cfg(feature = "std")]
+pub type RuntimeString = std::borrow::Cow<'static, str>;
+/// A String that is a `&'static str` on `no_std` and a `Cow<'static, str>` on `std`.
+#[cfg(not(feature = "std"))]
+pub type RuntimeString = &'static str;
+
+/// Create a const [`RuntimeString`].
+#[cfg(feature = "std")]
+#[macro_export]
+macro_rules! create_runtime_str {
+	( $y:expr ) => {{ std::borrow::Cow::Borrowed($y) }}
+}
+
+/// Create a const [`RuntimeString`].
+#[cfg(not(feature = "std"))]
+#[macro_export]
+macro_rules! create_runtime_str {
+	( $y:expr ) => {{ $y }}
+}
+
+#[cfg(feature = "std")]
+pub use serde::{Serialize, Deserialize, de::DeserializeOwned};
+use crate::traits::IdentifyAccount;
+
+/// Complex storage builder stuff.
+#[cfg(feature = "std")]
+pub trait BuildStorage: Sized {
+	/// Build the storage out of this builder.
+	fn build_storage(&self) -> Result<(StorageOverlay, ChildrenStorageOverlay), String> {
+		let mut storage = (Default::default(), Default::default());
+		self.assimilate_storage(&mut storage)?;
+		Ok(storage)
+	}
+	/// Assimilate the storage for this module into pre-existing overlays.
+	fn assimilate_storage(
+		&self,
+		storage: &mut (StorageOverlay, ChildrenStorageOverlay),
+	) -> Result<(), String>;
+}
+
+/// Something that can build the genesis storage of a module.
+#[cfg(feature = "std")]
+pub trait BuildModuleGenesisStorage<T, I>: Sized {
+	/// Create the module genesis storage into the given `storage` and `child_storage`.
+	fn build_module_genesis_storage(
+		&self,
+		storage: &mut (StorageOverlay, ChildrenStorageOverlay),
+	) -> Result<(), String>;
+}
+
+#[cfg(feature = "std")]
+impl BuildStorage for (StorageOverlay, ChildrenStorageOverlay) {
+	fn assimilate_storage(
+		&self,
+		storage: &mut (StorageOverlay, ChildrenStorageOverlay),
+	)-> Result<(), String> {
+		storage.0.extend(self.0.iter().map(|(k, v)| (k.clone(), v.clone())));
+		for (k, other_map) in self.1.iter() {
+			let k = k.clone();
+			if let Some(map) = storage.1.get_mut(&k) {
+				map.extend(other_map.iter().map(|(k, v)| (k.clone(), v.clone())));
+			} else {
+				storage.1.insert(k, other_map.clone());
+			}
+		}
+		Ok(())
+	}
+}
+
+/// Consensus engine unique ID.
+pub type ConsensusEngineId = [u8; 4];
+
+/// Signature verify that can work with any known signature types..
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+#[derive(Eq, PartialEq, Clone, Encode, Decode, RuntimeDebug)]
+pub enum MultiSignature {
+	/// An Ed25519 signature.
+	Ed25519(ed25519::Signature),
+	/// An Sr25519 signature.
+	Sr25519(sr25519::Signature),
+	/// An ECDSA/SECP256k1 signature.
+	Ecdsa(ecdsa::Signature),
+}
+
+impl From<ed25519::Signature> for MultiSignature {
+	fn from(x: ed25519::Signature) -> Self {
+		MultiSignature::Ed25519(x)
+	}
+}
+
+impl From<sr25519::Signature> for MultiSignature {
+	fn from(x: sr25519::Signature) -> Self {
+		MultiSignature::Sr25519(x)
+	}
+}
+
+impl From<ecdsa::Signature> for MultiSignature {
+	fn from(x: ecdsa::Signature) -> Self {
+		MultiSignature::Ecdsa(x)
+	}
+}
+
+impl Default for MultiSignature {
+	fn default() -> Self {
+		MultiSignature::Ed25519(Default::default())
+	}
+}
+
+/// Public key for any known crypto algorithm.
+#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub enum MultiSigner {
+	/// An Ed25519 identity.
+	Ed25519(ed25519::Public),
+	/// An Sr25519 identity.
+	Sr25519(sr25519::Public),
+	/// An SECP256k1/ECDSA identity (actually, the Blake2 hash of the pub key).
+	Ecdsa(ecdsa::Public),
+}
+
+impl Default for MultiSigner {
+	fn default() -> Self {
+		MultiSigner::Ed25519(Default::default())
+	}
+}
+
+/// NOTE: This implementations is required by `SimpleAddressDeterminator`,
+/// we convert the hash into some AccountId, it's fine to use any scheme.
+impl<T: Into<H256>> crypto::UncheckedFrom<T> for MultiSigner {
+	fn unchecked_from(x: T) -> Self {
+		ed25519::Public::unchecked_from(x.into()).into()
+	}
+}
+
+impl AsRef<[u8]> for MultiSigner {
+	fn as_ref(&self) -> &[u8] {
+		match *self {
+			MultiSigner::Ed25519(ref who) => who.as_ref(),
+			MultiSigner::Sr25519(ref who) => who.as_ref(),
+			MultiSigner::Ecdsa(ref who) => who.as_ref(),
+		}
+	}
+}
+
+impl traits::IdentifyAccount for MultiSigner {
+	type AccountId = AccountId32;
+	fn into_account(self) -> AccountId32 {
+		match self {
+			MultiSigner::Ed25519(who) => <[u8; 32]>::from(who).into(),
+			MultiSigner::Sr25519(who) => <[u8; 32]>::from(who).into(),
+			MultiSigner::Ecdsa(who) => runtime_io::hashing::blake2_256(who.as_ref()).into(),
+		}
+	}
+}
+
+impl From<ed25519::Public> for MultiSigner {
+	fn from(x: ed25519::Public) -> Self {
+		MultiSigner::Ed25519(x)
+	}
+}
+
+impl TryFrom<MultiSigner> for ed25519::Public {
+	type Error = ();
+	fn try_from(m: MultiSigner) -> Result<Self, Self::Error> {
+		if let MultiSigner::Ed25519(x) = m { Ok(x) } else { Err(()) }
+	}
+}
+
+impl From<sr25519::Public> for MultiSigner {
+	fn from(x: sr25519::Public) -> Self {
+		MultiSigner::Sr25519(x)
+	}
+}
+
+impl TryFrom<MultiSigner> for sr25519::Public {
+	type Error = ();
+	fn try_from(m: MultiSigner) -> Result<Self, Self::Error> {
+		if let MultiSigner::Sr25519(x) = m { Ok(x) } else { Err(()) }
+	}
+}
+
+impl From<ecdsa::Public> for MultiSigner {
+	fn from(x: ecdsa::Public) -> Self {
+		MultiSigner::Ecdsa(x)
+	}
+}
+
+impl TryFrom<MultiSigner> for ecdsa::Public {
+	type Error = ();
+	fn try_from(m: MultiSigner) -> Result<Self, Self::Error> {
+		if let MultiSigner::Ecdsa(x) = m { Ok(x) } else { Err(()) }
+	}
+}
+
+#[cfg(feature = "std")]
+impl std::fmt::Display for MultiSigner {
+	fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+		match *self {
+			MultiSigner::Ed25519(ref who) => write!(fmt, "ed25519: {}", who),
+			MultiSigner::Sr25519(ref who) => write!(fmt, "sr25519: {}", who),
+			MultiSigner::Ecdsa(ref who) => write!(fmt, "ecdsa: {}", who),
+		}
+	}
+}
+
+impl Verify for MultiSignature {
+	type Signer = MultiSigner;
+	fn verify<L: Lazy<[u8]>>(&self, mut msg: L, signer: &AccountId32) -> bool {
+		use primitives::crypto::Public;
+		match (self, signer) {
+			(MultiSignature::Ed25519(ref sig), who) => sig.verify(msg, &ed25519::Public::from_slice(who.as_ref())),
+			(MultiSignature::Sr25519(ref sig), who) => sig.verify(msg, &sr25519::Public::from_slice(who.as_ref())),
+			(MultiSignature::Ecdsa(ref sig), who) => {
+				let m = runtime_io::hashing::blake2_256(msg.get());
+				match runtime_io::crypto::secp256k1_ecdsa_recover_compressed(sig.as_ref(), &m) {
+					Ok(pubkey) =>
+						&runtime_io::hashing::blake2_256(pubkey.as_ref())
+							== <dyn AsRef<[u8; 32]>>::as_ref(who),
+					_ => false,
+				}
+			}
+		}
+	}
+}
+
+/// Signature verify that can work with any known signature types..
+#[derive(Eq, PartialEq, Clone, Default, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct AnySignature(H512);
+
+impl Verify for AnySignature {
+	type Signer = sr25519::Public;
+	fn verify<L: Lazy<[u8]>>(&self, mut msg: L, signer: &sr25519::Public) -> bool {
+		use primitives::crypto::Public;
+		let msg = msg.get();
+		sr25519::Signature::try_from(self.0.as_fixed_bytes().as_ref())
+			.map(|s| s.verify(msg, signer))
+			.unwrap_or(false)
+		|| ed25519::Signature::try_from(self.0.as_fixed_bytes().as_ref())
+			.map(|s| s.verify(msg, &ed25519::Public::from_slice(signer.as_ref())))
+			.unwrap_or(false)
+	}
+}
+
+impl From<sr25519::Signature> for AnySignature {
+	fn from(s: sr25519::Signature) -> Self {
+		AnySignature(s.into())
+	}
+}
+
+impl From<ed25519::Signature> for AnySignature {
+	fn from(s: ed25519::Signature) -> Self {
+		AnySignature(s.into())
+	}
+}
+
+impl From<DispatchError> for DispatchOutcome {
+	fn from(err: DispatchError) -> Self {
+		Err(err)
+	}
+}
+
+#[derive(Eq, PartialEq, Clone, Copy, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize))]
+/// Reason why a dispatch call failed
+pub struct DispatchError {
+	/// Module index, matching the metadata module index
+	pub module: Option<u8>,
+	/// Module specific error value
+	pub error: u8,
+	/// Optional error message.
+	#[codec(skip)]
+	pub message: Option<&'static str>,
+}
+
+impl DispatchError {
+	/// Create a new instance of `DispatchError`.
+	pub fn new(module: Option<u8>, error: u8, message: Option<&'static str>) -> Self {
+		Self {
+			module,
+			error,
+			message,
+		}
+	}
+}
+
+impl traits::Printable for DispatchError {
+	fn print(&self) {
+		"DispatchError".print();
+		if let Some(module) = self.module {
+			module.print();
+		}
+		self.error.print();
+		if let Some(msg) = self.message {
+			msg.print();
+		}
+	}
+}
+
+impl traits::ModuleDispatchError for &'static str {
+	fn as_u8(&self) -> u8 {
+		0
+	}
+
+	fn as_str(&self) -> &'static str {
+		self
+	}
+}
+
+impl From<&'static str> for DispatchError {
+	fn from(err: &'static str) -> DispatchError {
+		DispatchError::new(None, 0, Some(err))
+	}
+}
+
+/// This type specifies the outcome of dispatching a call to a module.
+///
+/// In case of failure an error specific to the module is returned.
+///
+/// Failure of the module call dispatching doesn't invalidate the extrinsic and it is still included
+/// in the block, therefore all state changes performed by the dispatched call are still persisted.
+///
+/// For example, if the dispatching of an extrinsic involves inclusion fee payment then these
+/// changes are going to be preserved even if the call dispatched failed.
+pub type DispatchOutcome = Result<(), DispatchError>;
+
+/// The result of applying of an extrinsic.
+///
+/// This type is typically used in the context of `BlockBuilder` to signal that the extrinsic
+/// in question cannot be included.
+///
+/// A block containing extrinsics that have a negative inclusion outcome is invalid. A negative
+/// result can only occur during the block production, where such extrinsics are detected and
+/// removed from the block that is being created and the transaction pool.
+///
+/// To rehash: every extrinsic in a valid block must return a positive `ApplyExtrinsicResult`.
+///
+/// Examples of reasons preventing inclusion in a block:
+/// - More block weight is required to process the extrinsic than is left in the block being built.
+///   This doesn't neccessarily mean that the extrinsic is invalid, since it can still be
+///   included in the next block if it has enough spare weight available.
+/// - The sender doesn't have enough funds to pay the transaction inclusion fee. Including such
+///   a transaction in the block doesn't make sense.
+/// - The extrinsic supplied a bad signature. This transaction won't become valid ever.
+pub type ApplyExtrinsicResult = Result<DispatchOutcome, transaction_validity::TransactionValidityError>;
+
+/// Verify a signature on an encoded value in a lazy manner. This can be
+/// an optimization if the signature scheme has an "unsigned" escape hash.
+pub fn verify_encoded_lazy<V: Verify, T: codec::Encode>(
+	sig: &V,
+	item: &T,
+	signer: &<V::Signer as IdentifyAccount>::AccountId
+) -> bool {
+	// The `Lazy<T>` trait expresses something like `X: FnMut<Output = for<'a> &'a T>`.
+	// unfortunately this is a lifetime relationship that can't
+	// be expressed without generic associated types, better unification of HRTBs in type position,
+	// and some kind of integration into the Fn* traits.
+	struct LazyEncode<F> {
+		inner: F,
+		encoded: Option<Vec<u8>>,
+	}
+
+	impl<F: Fn() -> Vec<u8>> traits::Lazy<[u8]> for LazyEncode<F> {
+		fn get(&mut self) -> &[u8] {
+			self.encoded.get_or_insert_with(&self.inner).as_slice()
+		}
+	}
+
+	sig.verify(
+		LazyEncode { inner: || item.encode(), encoded: None },
+		signer,
+	)
+}
+
+/// Helper macro for `impl_outer_config`
+#[macro_export]
+macro_rules! __impl_outer_config_types {
+	// Generic + Instance
+	(
+		$concrete:ident $config:ident $snake:ident { $instance:ident } < $ignore:ident >;
+		$( $rest:tt )*
+	) => {
+		#[cfg(any(feature = "std", test))]
+		pub type $config = $snake::GenesisConfig<$concrete, $snake::$instance>;
+		$crate::__impl_outer_config_types! { $concrete $( $rest )* }
+	};
+	// Generic
+	(
+		$concrete:ident $config:ident $snake:ident < $ignore:ident >;
+		$( $rest:tt )*
+	) => {
+		#[cfg(any(feature = "std", test))]
+		pub type $config = $snake::GenesisConfig<$concrete>;
+		$crate::__impl_outer_config_types! { $concrete $( $rest )* }
+	};
+	// No Generic and maybe Instance
+	(
+		$concrete:ident $config:ident $snake:ident $( { $instance:ident } )?;
+		$( $rest:tt )*
+	) => {
+		#[cfg(any(feature = "std", test))]
+		pub type $config = $snake::GenesisConfig;
+		$crate::__impl_outer_config_types! { $concrete $( $rest )* }
+	};
+	($concrete:ident) => ()
+}
+
+/// Implement the output "meta" module configuration struct,
+/// which is basically:
+/// pub struct GenesisConfig {
+/// 	rust_module_one: Option<ModuleOneConfig>,
+/// 	...
+/// }
+#[macro_export]
+macro_rules! impl_outer_config {
+	(
+		pub struct $main:ident for $concrete:ident {
+			$( $config:ident =>
+				$snake:ident $( $instance:ident )? $( <$generic:ident> )*, )*
+		}
+	) => {
+		$crate::__impl_outer_config_types! {
+			$concrete $( $config $snake $( { $instance } )? $( <$generic> )*; )*
+		}
+
+		$crate::paste::item! {
+			#[cfg(any(feature = "std", test))]
+			#[derive($crate::serde::Serialize, $crate::serde::Deserialize)]
+			#[serde(rename_all = "camelCase")]
+			#[serde(deny_unknown_fields)]
+			pub struct $main {
+				$(
+					pub [< $snake $(_ $instance )? >]: Option<$config>,
+				)*
+			}
+			#[cfg(any(feature = "std", test))]
+			impl $crate::BuildStorage for $main {
+				fn assimilate_storage(
+					&self,
+					storage: &mut ($crate::StorageOverlay, $crate::ChildrenStorageOverlay),
+				) -> std::result::Result<(), String> {
+					$(
+						if let Some(ref extra) = self.[< $snake $(_ $instance )? >] {
+							$crate::impl_outer_config! {
+								@CALL_FN
+								$concrete;
+								$snake;
+								$( $instance )?;
+								extra;
+								storage;
+							}
+						}
+					)*
+					Ok(())
+				}
+			}
+		}
+	};
+	(@CALL_FN
+		$runtime:ident;
+		$module:ident;
+		$instance:ident;
+		$extra:ident;
+		$storage:ident;
+	) => {
+		$crate::BuildModuleGenesisStorage::<$runtime, $module::$instance>::build_module_genesis_storage(
+			$extra,
+			$storage,
+		)?;
+	};
+	(@CALL_FN
+		$runtime:ident;
+		$module:ident;
+		;
+		$extra:ident;
+		$storage:ident;
+	) => {
+		$crate::BuildModuleGenesisStorage::<$runtime, $module::__InherentHiddenInstance>::build_module_genesis_storage(
+			$extra,
+			$storage,
+		)?;
+	}
+}
+
+/// Checks that `$x` is equal to `$y` with an error rate of `$error`.
+///
+/// # Example
+///
+/// ```rust
+/// # fn main() {
+/// sp_runtime::assert_eq_error_rate!(10, 10, 0);
+/// sp_runtime::assert_eq_error_rate!(10, 11, 1);
+/// sp_runtime::assert_eq_error_rate!(12, 10, 2);
+/// # }
+/// ```
+///
+/// ```rust,should_panic
+/// # fn main() {
+/// sp_runtime::assert_eq_error_rate!(12, 10, 1);
+/// # }
+/// ```
+#[macro_export]
+#[cfg(feature = "std")]
+macro_rules! assert_eq_error_rate {
+	($x:expr, $y:expr, $error:expr $(,)?) => {
+		assert!(
+			($x) >= (($y) - ($error)) && ($x) <= (($y) + ($error)),
+			"{:?} != {:?} (with error rate {:?})",
+			$x,
+			$y,
+			$error,
+		);
+	};
+}
+
+/// Simple blob to hold an extrinsic without committing to its format and ensure it is serialized
+/// correctly.
+#[derive(PartialEq, Eq, Clone, Default, Encode, Decode)]
+pub struct OpaqueExtrinsic(pub Vec<u8>);
+
+impl rstd::fmt::Debug for OpaqueExtrinsic {
+	#[cfg(feature = "std")]
+	fn fmt(&self, fmt: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
+		write!(fmt, "{}", primitives::hexdisplay::HexDisplay::from(&self.0))
+	}
+
+	#[cfg(not(feature = "std"))]
+	fn fmt(&self, _fmt: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
+		Ok(())
+	}
+}
+
+
+#[cfg(feature = "std")]
+impl ::serde::Serialize for OpaqueExtrinsic {
+	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: ::serde::Serializer {
+		codec::Encode::using_encoded(&self.0, |bytes| ::primitives::bytes::serialize(bytes, seq))
+	}
+}
+
+#[cfg(feature = "std")]
+impl<'a> ::serde::Deserialize<'a> for OpaqueExtrinsic {
+	fn deserialize<D>(de: D) -> Result<Self, D::Error> where D: ::serde::Deserializer<'a> {
+		let r = ::primitives::bytes::deserialize(de)?;
+		Decode::decode(&mut &r[..])
+			.map_err(|e| ::serde::de::Error::custom(format!("Decode error: {}", e)))
+	}
+}
+
+impl traits::Extrinsic for OpaqueExtrinsic {
+	type Call = ();
+	type SignaturePayload = ();
+}
+
+/// Print something that implements `Printable` from the runtime.
+pub fn print(print: impl traits::Printable) {
+	print.print();
+}
+
+#[cfg(test)]
+mod tests {
+	use crate::DispatchError;
+	use codec::{Encode, Decode};
+
+	#[test]
+	fn opaque_extrinsic_serialization() {
+		let ex = super::OpaqueExtrinsic(vec![1, 2, 3, 4]);
+		assert_eq!(serde_json::to_string(&ex).unwrap(), "\"0x1001020304\"".to_owned());
+	}
+
+	#[test]
+	fn dispatch_error_encoding() {
+		let error = DispatchError {
+			module: Some(1),
+			error: 2,
+			message: Some("error message"),
+		};
+		let encoded = error.encode();
+		let decoded = DispatchError::decode(&mut &encoded[..]).unwrap();
+		assert_eq!(encoded, vec![1, 1, 2]);
+		assert_eq!(
+			decoded,
+			DispatchError {
+				module: Some(1),
+				error: 2,
+				message: None,
+			},
+		);
+	}
+}

substrate/primitives/runtime/src/offchain/http.rs

@@ -0,0 +1,606 @@
+// Copyright 2019 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/>.
+
+//! A high-level helpers for making HTTP requests from Offchain Workers.
+//!
+//! `sp-io` crate exposes a low level methods to make and control HTTP requests
+//! available only for Offchain Workers. Those might be hard to use
+//! and usually that level of control is not really necessary.
+//! This module aims to provide high-level wrappers for those APIs
+//! to simplify making HTTP requests.
+//!
+//!
+//! Example:
+//! ```rust,no_run
+//! use sp_runtime::offchain::http::Request;
+//!
+//! // initiate a GET request to localhost:1234
+//! let request: Request = Request::get("http://localhost:1234");
+//! let pending = request
+//! 	.add_header("X-Auth", "hunter2")
+//! 	.send()
+//! 	.unwrap();
+//!
+//! // wait for the response indefinitely
+//! let mut response = pending.wait().unwrap();
+//!
+//! // then check the headers
+//! let mut headers = response.headers().into_iter();
+//! assert_eq!(headers.current(), None);
+//!
+//! // and collect the body
+//! let body = response.body();
+//! assert_eq!(body.clone().collect::<Vec<_>>(), b"1234".to_vec());
+//! assert_eq!(body.error(), &None);
+//! ```
+
+use rstd::str;
+use rstd::prelude::Vec;
+#[cfg(not(feature = "std"))]
+use rstd::prelude::vec;
+use primitives::RuntimeDebug;
+use primitives::offchain::{
+	Timestamp,
+	HttpRequestId as RequestId,
+	HttpRequestStatus as RequestStatus,
+	HttpError,
+};
+
+/// Request method (HTTP verb)
+#[derive(Clone, PartialEq, Eq, RuntimeDebug)]
+pub enum Method {
+	/// GET request
+	Get,
+	/// POST request
+	Post,
+	/// PUT request
+	Put,
+	/// PATCH request
+	Patch,
+	/// DELETE request
+	Delete,
+	/// Custom verb
+	Other(&'static str),
+}
+
+impl AsRef<str> for Method {
+	fn as_ref(&self) -> &str {
+		match *self {
+			Method::Get => "GET",
+			Method::Post => "POST",
+			Method::Put => "PUT",
+			Method::Patch => "PATCH",
+			Method::Delete => "DELETE",
+			Method::Other(m) => m,
+		}
+	}
+}
+
+mod header {
+	use super::*;
+
+	/// A header type.
+	#[derive(Clone, PartialEq, Eq, RuntimeDebug)]
+	pub struct Header {
+		name: Vec<u8>,
+		value: Vec<u8>,
+	}
+
+	impl Header {
+		/// Creates new header given it's name and value.
+		pub fn new(name: &str, value: &str) -> Self {
+			Header {
+				name: name.as_bytes().to_vec(),
+				value: value.as_bytes().to_vec(),
+			}
+		}
+
+		/// Returns the name of this header.
+		pub fn name(&self) -> &str {
+			// Header keys are always produced from `&str` so this is safe.
+			// we don't store them as `Strings` to avoid bringing `alloc::String` to rstd
+			// or here.
+			unsafe { str::from_utf8_unchecked(&self.name) }
+		}
+
+		/// Returns the value of this header.
+		pub fn value(&self) -> &str {
+			// Header values are always produced from `&str` so this is safe.
+			// we don't store them as `Strings` to avoid bringing `alloc::String` to rstd
+			// or here.
+			unsafe { str::from_utf8_unchecked(&self.value) }
+		}
+	}
+}
+
+/// An HTTP request builder.
+#[derive(Clone, PartialEq, Eq, RuntimeDebug)]
+pub struct Request<'a, T = Vec<&'static [u8]>> {
+	/// Request method
+	pub method: Method,
+	/// Request URL
+	pub url: &'a str,
+	/// Body of the request
+	pub body: T,
+	/// Deadline to finish sending the request
+	pub deadline: Option<Timestamp>,
+	/// Request list of headers.
+	headers: Vec<header::Header>,
+}
+
+impl<T: Default> Default for Request<'static, T> {
+	fn default() -> Self {
+		Request {
+			method: Method::Get,
+			url: "http://localhost",
+			headers: Vec::new(),
+			body: Default::default(),
+			deadline: None,
+		}
+	}
+}
+
+impl<'a> Request<'a> {
+	/// Start a simple GET request
+	pub fn get(url: &'a str) -> Self {
+		Self::new(url)
+	}
+}
+
+impl<'a, T> Request<'a, T> {
+	/// Create new POST request with given body.
+	pub fn post(url: &'a str, body: T) -> Self {
+		let req: Request = Request::default();
+
+		Request {
+			url,
+			body,
+			method: Method::Post,
+			headers: req.headers,
+			deadline: req.deadline,
+		}
+	}
+}
+
+impl<'a, T: Default> Request<'a, T> {
+	/// Create new Request builder with given URL and body.
+	pub fn new(url: &'a str) -> Self {
+		Request::default().url(url)
+	}
+
+	/// Change the method of the request
+	pub fn method(mut self, method: Method) -> Self {
+		self.method = method;
+		self
+	}
+
+	/// Change the URL of the request.
+	pub fn url(mut self, url: &'a str) -> Self {
+		self.url = url;
+		self
+	}
+
+	/// Set the body of the request.
+	pub fn body(mut self, body: T) -> Self {
+		self.body = body;
+		self
+	}
+
+	/// Add a header.
+	pub fn add_header(mut self, name: &str, value: &str) -> Self {
+		self.headers.push(header::Header::new(name, value));
+		self
+	}
+
+	/// Set the deadline of the request.
+	pub fn deadline(mut self, deadline: Timestamp) -> Self {
+		self.deadline = Some(deadline);
+		self
+	}
+}
+
+impl<'a, I: AsRef<[u8]>, T: IntoIterator<Item=I>> Request<'a, T> {
+	/// Send the request and return a handle.
+	///
+	/// Err is returned in case the deadline is reached
+	/// or the request timeouts.
+	pub fn send(self) -> Result<PendingRequest, HttpError> {
+		let meta = &[];
+
+		// start an http request.
+		let id = runtime_io::offchain::http_request_start(
+			self.method.as_ref(),
+			self.url,
+			meta,
+		).map_err(|_| HttpError::IoError)?;
+
+		// add custom headers
+		for header in &self.headers {
+			runtime_io::offchain::http_request_add_header(
+				id,
+				header.name(),
+				header.value(),
+			).map_err(|_| HttpError::IoError)?
+		}
+
+		// write body
+		for chunk in self.body {
+			runtime_io::offchain::http_request_write_body(id, chunk.as_ref(), self.deadline)?;
+		}
+
+		// finalise the request
+		runtime_io::offchain::http_request_write_body(id, &[], self.deadline)?;
+
+		Ok(PendingRequest {
+			id,
+		})
+	}
+}
+
+/// A request error
+#[derive(Clone, PartialEq, Eq, RuntimeDebug)]
+pub enum Error {
+	/// Deadline has been reached.
+	DeadlineReached,
+	/// Request had timed out.
+	IoError,
+	/// Unknown error has been ecountered.
+	Unknown,
+}
+
+/// A struct representing an uncompleted http request.
+#[derive(PartialEq, Eq, RuntimeDebug)]
+pub struct PendingRequest {
+	/// Request ID
+	pub id: RequestId,
+}
+
+/// A result of waiting for a pending request.
+pub type HttpResult = Result<Response, Error>;
+
+impl PendingRequest {
+	/// Wait for the request to complete.
+	///
+	/// NOTE this waits for the request indefinitely.
+	pub fn wait(self) -> HttpResult {
+		match self.try_wait(None) {
+			Ok(res) => res,
+			Err(_) => panic!("Since `None` is passed we will never get a deadline error; qed"),
+		}
+	}
+
+	/// Attempts to wait for the request to finish,
+	/// but will return `Err` in case the deadline is reached.
+	pub fn try_wait(self, deadline: impl Into<Option<Timestamp>>) -> Result<HttpResult, PendingRequest> {
+		Self::try_wait_all(vec![self], deadline).pop().expect("One request passed, one status received; qed")
+	}
+
+	/// Wait for all provided requests.
+	pub fn wait_all(requests: Vec<PendingRequest>) -> Vec<HttpResult> {
+		Self::try_wait_all(requests, None)
+			.into_iter()
+			.map(|r| match r {
+				Ok(r) => r,
+				Err(_) => panic!("Since `None` is passed we will never get a deadline error; qed"),
+			})
+			.collect()
+	}
+
+	/// Attempt to wait for all provided requests, but up to given deadline.
+	///
+	/// Requests that are complete will resolve to an `Ok` others will return a `DeadlineReached` error.
+	pub fn try_wait_all(
+		requests: Vec<PendingRequest>,
+		deadline: impl Into<Option<Timestamp>>
+	) -> Vec<Result<HttpResult, PendingRequest>> {
+		let ids = requests.iter().map(|r| r.id).collect::<Vec<_>>();
+		let statuses = runtime_io::offchain::http_response_wait(&ids, deadline.into());
+
+		statuses
+			.into_iter()
+			.zip(requests.into_iter())
+			.map(|(status, req)| match status {
+				RequestStatus::DeadlineReached => Err(req),
+				RequestStatus::IoError => Ok(Err(Error::IoError)),
+				RequestStatus::Invalid => Ok(Err(Error::Unknown)),
+				RequestStatus::Finished(code) => Ok(Ok(Response::new(req.id, code))),
+			})
+			.collect()
+	}
+}
+
+/// A HTTP response.
+#[derive(RuntimeDebug)]
+pub struct Response {
+	/// Request id
+	pub id: RequestId,
+	/// Response status code
+	pub code: u16,
+	/// A collection of headers.
+	headers: Option<Headers>,
+}
+
+impl Response {
+	fn new(id: RequestId, code: u16) -> Self {
+		Self {
+			id,
+			code,
+			headers: None,
+		}
+	}
+
+	/// Retrieve the headers for this response.
+	pub fn headers(&mut self) -> &Headers {
+		if self.headers.is_none() {
+			self.headers = Some(
+				Headers { raw: runtime_io::offchain::http_response_headers(self.id) },
+			);
+		}
+		self.headers.as_ref().expect("Headers were just set; qed")
+	}
+
+	/// Retrieve the body of this response.
+	pub fn body(&self) -> ResponseBody {
+		ResponseBody::new(self.id)
+	}
+}
+
+/// A buffered byte iterator over response body.
+///
+/// Note that reading the body may return `None` in following cases:
+/// 1. Either the deadline you've set is reached (check via `#error`;
+///	   In such case you can resume the reader by setting a new deadline)
+/// 2. Or because of IOError. In such case the reader is not resumable and will keep
+///    returning `None`.
+/// 3. The body has been returned. The reader will keep returning `None`.
+#[derive(Clone)]
+pub struct ResponseBody {
+	id: RequestId,
+	error: Option<HttpError>,
+	buffer: [u8; 4096],
+	filled_up_to: Option<usize>,
+	position: usize,
+	deadline: Option<Timestamp>,
+}
+
+#[cfg(feature = "std")]
+impl std::fmt::Debug for ResponseBody {
+	fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+		fmt.debug_struct("ResponseBody")
+			.field("id", &self.id)
+			.field("error", &self.error)
+			.field("buffer", &self.buffer.len())
+			.field("filled_up_to", &self.filled_up_to)
+			.field("position", &self.position)
+			.field("deadline", &self.deadline)
+			.finish()
+	}
+}
+
+impl ResponseBody {
+	fn new(id: RequestId) -> Self {
+		ResponseBody {
+			id,
+			error: None,
+			buffer: [0_u8; 4096],
+			filled_up_to: None,
+			position: 0,
+			deadline: None,
+		}
+	}
+
+	/// Set the deadline for reading the body.
+	pub fn deadline(&mut self, deadline: impl Into<Option<Timestamp>>) {
+		self.deadline = deadline.into();
+		self.error = None;
+	}
+
+	/// Return an error that caused the iterator to return `None`.
+	///
+	/// If the error is `DeadlineReached` you can resume the iterator by setting
+	/// a new deadline.
+	pub fn error(&self) -> &Option<HttpError> {
+		&self.error
+	}
+}
+
+impl Iterator for ResponseBody {
+	type Item = u8;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		if self.error.is_some() {
+			return None;
+		}
+
+		if self.filled_up_to.is_none() {
+			let result = runtime_io::offchain::http_response_read_body(
+				self.id,
+				&mut self.buffer,
+				self.deadline);
+			match result {
+				Err(e) => {
+					self.error = Some(e);
+					return None;
+				}
+				Ok(0) => {
+					return None;
+				}
+				Ok(size) => {
+					self.position = 0;
+					self.filled_up_to = Some(size as usize);
+				}
+			}
+		}
+
+		if Some(self.position) == self.filled_up_to {
+			self.filled_up_to = None;
+			return self.next();
+		}
+
+		let result = self.buffer[self.position];
+		self.position += 1;
+		Some(result)
+	}
+}
+
+/// A collection of Headers in the response.
+#[derive(Clone, PartialEq, Eq, RuntimeDebug)]
+pub struct Headers {
+	/// Raw headers
+	pub raw: Vec<(Vec<u8>, Vec<u8>)>,
+}
+
+impl Headers {
+	/// Retrieve a single header from the list of headers.
+	///
+	/// Note this method is linearly looking from all the headers
+	/// comparing them with the needle byte-by-byte.
+	/// If you want to consume multiple headers it's better to iterate
+	/// and collect them on your own.
+	pub fn find(&self, name: &str) -> Option<&str> {
+		let raw = name.as_bytes();
+		for &(ref key, ref val) in &self.raw {
+			if &**key == raw {
+				return str::from_utf8(&val).ok()
+			}
+		}
+		None
+	}
+
+	/// Convert this headers into an iterator.
+	pub fn into_iter(&self) -> HeadersIterator {
+		HeadersIterator { collection: &self.raw, index: None }
+	}
+}
+
+/// A custom iterator traversing all the headers.
+#[derive(Clone, RuntimeDebug)]
+pub struct HeadersIterator<'a> {
+	collection: &'a [(Vec<u8>, Vec<u8>)],
+	index: Option<usize>,
+}
+
+impl<'a> HeadersIterator<'a> {
+	/// Move the iterator to the next position.
+	///
+	/// Returns `true` is `current` has been set by this call.
+	pub fn next(&mut self) -> bool {
+		let index = self.index.map(|x| x + 1).unwrap_or(0);
+		self.index = Some(index);
+		index < self.collection.len()
+	}
+
+	/// Returns current element (if any).
+	///
+	/// Note that you have to call `next` prior to calling this
+	pub fn current(&self) -> Option<(&str, &str)> {
+		self.collection.get(self.index?)
+			.map(|val| (str::from_utf8(&val.0).unwrap_or(""), str::from_utf8(&val.1).unwrap_or("")))
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use runtime_io::TestExternalities;
+	use primitives::offchain::{
+		OffchainExt,
+		testing,
+	};
+
+	#[test]
+	fn should_send_a_basic_request_and_get_response() {
+		let (offchain, state) = testing::TestOffchainExt::new();
+		let mut t = TestExternalities::default();
+		t.register_extension(OffchainExt::new(offchain));
+
+		t.execute_with(|| {
+			let request: Request = Request::get("http://localhost:1234");
+			let pending = request
+				.add_header("X-Auth", "hunter2")
+				.send()
+				.unwrap();
+			// make sure it's sent correctly
+			state.write().fulfill_pending_request(
+				0,
+				testing::PendingRequest {
+					method: "GET".into(),
+					uri: "http://localhost:1234".into(),
+					headers: vec![("X-Auth".into(), "hunter2".into())],
+					sent: true,
+					..Default::default()
+				},
+				b"1234".to_vec(),
+				None,
+			);
+
+			// wait
+			let mut response = pending.wait().unwrap();
+
+			// then check the response
+			let mut headers = response.headers().into_iter();
+			assert_eq!(headers.current(), None);
+			assert_eq!(headers.next(), false);
+			assert_eq!(headers.current(), None);
+
+			let body = response.body();
+			assert_eq!(body.clone().collect::<Vec<_>>(), b"1234".to_vec());
+			assert_eq!(body.error(), &None);
+		})
+	}
+
+	#[test]
+	fn should_send_a_post_request() {
+		let (offchain, state) = testing::TestOffchainExt::new();
+		let mut t = TestExternalities::default();
+		t.register_extension(OffchainExt::new(offchain));
+
+		t.execute_with(|| {
+			let pending = Request::default()
+				.method(Method::Post)
+				.url("http://localhost:1234")
+				.body(vec![b"1234"])
+				.send()
+				.unwrap();
+			// make sure it's sent correctly
+			state.write().fulfill_pending_request(
+				0,
+				testing::PendingRequest {
+					method: "POST".into(),
+					uri: "http://localhost:1234".into(),
+					body: b"1234".to_vec(),
+					sent: true,
+					..Default::default()
+				},
+				b"1234".to_vec(),
+				Some(("Test".to_owned(), "Header".to_owned())),
+			);
+
+			// wait
+			let mut response = pending.wait().unwrap();
+
+			// then check the response
+			let mut headers = response.headers().into_iter();
+			assert_eq!(headers.current(), None);
+			assert_eq!(headers.next(), true);
+			assert_eq!(headers.current(), Some(("Test", "Header")));
+
+			let body = response.body();
+			assert_eq!(body.clone().collect::<Vec<_>>(), b"1234".to_vec());
+			assert_eq!(body.error(), &None);
+		})
+	}
+}

substrate/primitives/runtime/src/offchain/mod.rs

@@ -0,0 +1,19 @@
+// Copyright 2019 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/>.
+
+//! A collection of higher lever helpers for offchain calls.
+
+pub mod http;

substrate/primitives/runtime/src/random_number_generator.rs

@@ -0,0 +1,103 @@
+// Copyright 2017-2019 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/>.
+
+//! A simple pseudo random number generator that allows a stream of random numbers to be efficiently
+//! created from a single initial seed hash.
+
+use codec::{Encode, Decode};
+use crate::traits::{Hash, TrailingZeroInput};
+
+/// Pseudo-random number streamer. This retains the state of the random number stream. It's as
+/// secure as the combination of the seed with which it is constructed and the hash function it uses
+/// to cycle elements.
+///
+/// It can be saved and later reloaded using the Codec traits.
+///
+/// Example:
+/// ```
+/// use sp_runtime::traits::{Hash, BlakeTwo256};
+/// use sp_runtime::RandomNumberGenerator;
+/// let random_seed = BlakeTwo256::hash(b"Sixty-nine");
+/// let mut rng = <RandomNumberGenerator<BlakeTwo256>>::new(random_seed);
+/// assert_eq!(rng.pick_u32(100), 59);
+/// assert_eq!(rng.pick_item(&[1, 2, 3]), Some(&1));
+/// ```
+///
+/// This can use any cryptographic `Hash` function as the means of entropy-extension, and avoids
+/// needless extensions of entropy.
+///
+/// If you're persisting it over blocks, be aware that the sequence will start to repeat. This won't
+/// be a practical issue unless you're using tiny hash types (e.g. 64-bit) and pulling hundred of
+/// megabytes of data from it.
+#[derive(Encode, Decode)]
+pub struct RandomNumberGenerator<Hashing: Hash> {
+	current: Hashing::Output,
+	offset: u32,
+}
+
+impl<Hashing: Hash> RandomNumberGenerator<Hashing> {
+	/// A new source of random data.
+	pub fn new(seed: Hashing::Output) -> Self {
+		Self {
+			current: seed,
+			offset: 0,
+		}
+	}
+
+	fn offset(&self) -> usize { self.offset as usize }
+
+	/// Returns a number at least zero, at most `max`.
+	pub fn pick_u32(&mut self, max: u32) -> u32 {
+		let needed = (4 - max.leading_zeros() / 8) as usize;
+		let top = ((1 << (needed as u64 * 8)) / ((max + 1) as u64) * ((max + 1) as u64) - 1) as u32;
+		loop {
+			if self.offset() + needed > self.current.as_ref().len() {
+				// rehash
+				self.current = Hashing::hash(self.current.as_ref());
+				self.offset = 0;
+			}
+			let data = &self.current.as_ref()[self.offset()..self.offset() + needed];
+			self.offset += needed as u32;
+			let raw = u32::decode(&mut TrailingZeroInput::new(data)).unwrap_or(0);
+			if raw <= top {
+				break if max < u32::max_value() {
+					raw % (max + 1)
+				} else {
+					raw
+				}
+			}
+		}
+	}
+
+	/// Returns a number at least zero, at most `max`.
+	///
+	/// This returns a `usize`, but internally it only uses `u32` so avoid consensus problems.
+	pub fn pick_usize(&mut self, max: usize) -> usize {
+		self.pick_u32(max as u32) as usize
+	}
+
+	/// Pick a random element from an array of `items`.
+	///
+	/// This is guaranteed to return `Some` except in the case that the given array `items` is
+	/// empty.
+	pub fn pick_item<'a, T>(&mut self, items: &'a [T]) -> Option<&'a T> {
+		if items.is_empty() {
+			None
+		} else {
+			Some(&items[self.pick_usize(items.len() - 1)])
+		}
+	}
+}

substrate/primitives/runtime/src/testing.rs

@@ -0,0 +1,368 @@
+// Copyright 2017-2019 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/>.
+
+//! Testing utilities.
+
+use serde::{Serialize, Serializer, Deserialize, de::Error as DeError, Deserializer};
+use std::{fmt::Debug, ops::Deref, fmt, cell::RefCell};
+use crate::codec::{Codec, Encode, Decode};
+use crate::traits::{
+	self, Checkable, Applyable, BlakeTwo256, OpaqueKeys,
+	SignedExtension, Dispatchable,
+};
+#[allow(deprecated)]
+use crate::traits::ValidateUnsigned;
+use crate::{generic, KeyTypeId, ApplyExtrinsicResult};
+pub use primitives::{H256, sr25519};
+use primitives::{crypto::{CryptoType, Dummy, key_types, Public}, U256};
+use crate::transaction_validity::{TransactionValidity, TransactionValidityError};
+
+/// Authority Id
+#[derive(Default, PartialEq, Eq, Clone, Encode, Decode, Debug, Hash, Serialize, Deserialize, PartialOrd, Ord)]
+pub struct UintAuthorityId(pub u64);
+
+impl From<u64> for UintAuthorityId {
+	fn from(id: u64) -> Self {
+		UintAuthorityId(id)
+	}
+}
+
+impl From<UintAuthorityId> for u64 {
+	fn from(id: UintAuthorityId) -> u64 {
+		id.0
+	}
+}
+
+impl UintAuthorityId {
+	/// Convert this authority id into a public key.
+	pub fn to_public_key<T: Public>(&self) -> T {
+		let bytes: [u8; 32] = U256::from(self.0).into();
+		T::from_slice(&bytes)
+	}
+}
+
+impl CryptoType for UintAuthorityId {
+	type Pair = Dummy;
+}
+
+impl AsRef<[u8]> for UintAuthorityId {
+	fn as_ref(&self) -> &[u8] {
+		// Unsafe, i know, but it's test code and it's just there because it's really convenient to
+		// keep `UintAuthorityId` as a u64 under the hood.
+		unsafe {
+			std::slice::from_raw_parts(&self.0 as *const u64 as *const _, std::mem::size_of::<u64>())
+		}
+	}
+}
+
+thread_local! {
+	/// A list of all UintAuthorityId keys returned to the runtime.
+	static ALL_KEYS: RefCell<Vec<UintAuthorityId>> = RefCell::new(vec![]);
+}
+
+impl UintAuthorityId {
+	/// Set the list of keys returned by the runtime call for all keys of that type.
+	pub fn set_all_keys<T: Into<UintAuthorityId>>(keys: impl IntoIterator<Item=T>) {
+		ALL_KEYS.with(|l| *l.borrow_mut() = keys.into_iter().map(Into::into).collect())
+	}
+}
+
+impl app_crypto::RuntimeAppPublic for UintAuthorityId {
+	const ID: KeyTypeId = key_types::DUMMY;
+
+	type Signature = u64;
+
+	fn all() -> Vec<Self> {
+		ALL_KEYS.with(|l| l.borrow().clone())
+	}
+
+	fn generate_pair(_: Option<Vec<u8>>) -> Self {
+		use rand::RngCore;
+		UintAuthorityId(rand::thread_rng().next_u64())
+	}
+
+	fn sign<M: AsRef<[u8]>>(&self, msg: &M) -> Option<Self::Signature> {
+		let mut signature = [0u8; 8];
+		msg.as_ref().iter()
+			.chain(std::iter::repeat(&42u8))
+			.take(8)
+			.enumerate()
+			.for_each(|(i, v)| { signature[i] = *v; });
+
+		Some(u64::from_le_bytes(signature))
+	}
+
+	fn verify<M: AsRef<[u8]>>(&self, msg: &M, signature: &Self::Signature) -> bool {
+		let mut msg_signature = [0u8; 8];
+		msg.as_ref().iter()
+			.chain(std::iter::repeat(&42))
+			.take(8)
+			.enumerate()
+			.for_each(|(i, v)| { msg_signature[i] = *v; });
+
+		u64::from_le_bytes(msg_signature) == *signature
+	}
+}
+
+impl OpaqueKeys for UintAuthorityId {
+	type KeyTypeIdProviders = ();
+
+	fn key_ids() -> &'static [KeyTypeId] {
+		&[key_types::DUMMY]
+	}
+
+	fn get_raw(&self, _: KeyTypeId) -> &[u8] {
+		self.as_ref()
+	}
+
+	fn get<T: Decode>(&self, _: KeyTypeId) -> Option<T> {
+		self.using_encoded(|mut x| T::decode(&mut x)).ok()
+	}
+}
+
+impl crate::BoundToRuntimeAppPublic for UintAuthorityId {
+	type Public = Self;
+}
+
+/// Digest item
+pub type DigestItem = generic::DigestItem<H256>;
+
+/// Header Digest
+pub type Digest = generic::Digest<H256>;
+
+/// Block Header
+#[derive(PartialEq, Eq, Clone, Serialize, Debug, Encode, Decode, Default)]
+#[serde(rename_all = "camelCase")]
+#[serde(deny_unknown_fields)]
+pub struct Header {
+	/// Parent hash
+	pub parent_hash: H256,
+	/// Block Number
+	pub number: u64,
+	/// Post-execution state trie root
+	pub state_root: H256,
+	/// Merkle root of block's extrinsics
+	pub extrinsics_root: H256,
+	/// Digest items
+	pub digest: Digest,
+}
+
+impl traits::Header for Header {
+	type Number = u64;
+	type Hashing = BlakeTwo256;
+	type Hash = H256;
+
+	fn number(&self) -> &Self::Number { &self.number }
+	fn set_number(&mut self, num: Self::Number) { self.number = num }
+
+	fn extrinsics_root(&self) -> &Self::Hash { &self.extrinsics_root }
+	fn set_extrinsics_root(&mut self, root: Self::Hash) { self.extrinsics_root = root }
+
+	fn state_root(&self) -> &Self::Hash { &self.state_root }
+	fn set_state_root(&mut self, root: Self::Hash) { self.state_root = root }
+
+	fn parent_hash(&self) -> &Self::Hash { &self.parent_hash }
+	fn set_parent_hash(&mut self, hash: Self::Hash) { self.parent_hash = hash }
+
+	fn digest(&self) -> &Digest { &self.digest }
+	fn digest_mut(&mut self) -> &mut Digest { &mut self.digest }
+
+	fn new(
+		number: Self::Number,
+		extrinsics_root: Self::Hash,
+		state_root: Self::Hash,
+		parent_hash: Self::Hash,
+		digest: Digest,
+	) -> Self {
+		Header {
+			number,
+			extrinsics_root,
+			state_root,
+			parent_hash,
+			digest,
+		}
+	}
+}
+
+impl Header {
+	/// A new header with the given number and default hash for all other fields.
+	pub fn new_from_number(number: <Self as traits::Header>::Number) -> Self {
+		Self {
+			number,
+			..Default::default()
+		}
+	}
+}
+
+impl<'a> Deserialize<'a> for Header {
+	fn deserialize<D: Deserializer<'a>>(de: D) -> Result<Self, D::Error> {
+		let r = <Vec<u8>>::deserialize(de)?;
+		Decode::decode(&mut &r[..])
+			.map_err(|e| DeError::custom(format!("Invalid value passed into decode: {}", e.what())))
+	}
+}
+
+/// An opaque extrinsic wrapper type.
+#[derive(PartialEq, Eq, Clone, Debug, Encode, Decode)]
+pub struct ExtrinsicWrapper<Xt>(Xt);
+
+impl<Xt> traits::Extrinsic for ExtrinsicWrapper<Xt> {
+	type Call = ();
+	type SignaturePayload = ();
+
+	fn is_signed(&self) -> Option<bool> {
+		None
+	}
+}
+
+impl<Xt: Encode> serde::Serialize for ExtrinsicWrapper<Xt> {
+	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: ::serde::Serializer {
+		self.using_encoded(|bytes| seq.serialize_bytes(bytes))
+	}
+}
+
+impl<Xt> From<Xt> for ExtrinsicWrapper<Xt> {
+	fn from(xt: Xt) -> Self {
+		ExtrinsicWrapper(xt)
+	}
+}
+
+impl<Xt> Deref for ExtrinsicWrapper<Xt> {
+	type Target = Xt;
+
+	fn deref(&self) -> &Self::Target {
+		&self.0
+	}
+}
+
+/// Testing block
+#[derive(PartialEq, Eq, Clone, Serialize, Debug, Encode, Decode)]
+pub struct Block<Xt> {
+	/// Block header
+	pub header: Header,
+	/// List of extrinsics
+	pub extrinsics: Vec<Xt>,
+}
+
+impl<Xt: 'static + Codec + Sized + Send + Sync + Serialize + Clone + Eq + Debug + traits::Extrinsic> traits::Block
+	for Block<Xt>
+{
+	type Extrinsic = Xt;
+	type Header = Header;
+	type Hash = <Header as traits::Header>::Hash;
+
+	fn header(&self) -> &Self::Header {
+		&self.header
+	}
+	fn extrinsics(&self) -> &[Self::Extrinsic] {
+		&self.extrinsics[..]
+	}
+	fn deconstruct(self) -> (Self::Header, Vec<Self::Extrinsic>) {
+		(self.header, self.extrinsics)
+	}
+	fn new(header: Self::Header, extrinsics: Vec<Self::Extrinsic>) -> Self {
+		Block { header, extrinsics }
+	}
+	fn encode_from(header: &Self::Header, extrinsics: &[Self::Extrinsic]) -> Vec<u8> {
+		(header, extrinsics).encode()
+	}
+}
+
+impl<'a, Xt> Deserialize<'a> for Block<Xt> where Block<Xt>: Decode {
+	fn deserialize<D: Deserializer<'a>>(de: D) -> Result<Self, D::Error> {
+		let r = <Vec<u8>>::deserialize(de)?;
+		Decode::decode(&mut &r[..])
+			.map_err(|e| DeError::custom(format!("Invalid value passed into decode: {}", e.what())))
+	}
+}
+
+/// Test transaction, tuple of (sender, call, signed_extra)
+/// with index only used if sender is some.
+///
+/// If sender is some then the transaction is signed otherwise it is unsigned.
+#[derive(PartialEq, Eq, Clone, Encode, Decode)]
+pub struct TestXt<Call, Extra>(pub Option<(u64, Extra)>, pub Call);
+
+impl<Call, Extra> Serialize for TestXt<Call, Extra> where TestXt<Call, Extra>: Encode {
+	fn serialize<S>(&self, seq: S) -> Result<S::Ok, S::Error> where S: Serializer {
+		self.using_encoded(|bytes| seq.serialize_bytes(bytes))
+	}
+}
+
+impl<Call, Extra> Debug for TestXt<Call, Extra> {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write!(f, "TestXt({:?}, ...)", self.0.as_ref().map(|x| &x.0))
+	}
+}
+
+impl<Call: Codec + Sync + Send, Context, Extra> Checkable<Context> for TestXt<Call, Extra> {
+	type Checked = Self;
+	fn check(self, _: &Context) -> Result<Self::Checked, TransactionValidityError> { Ok(self) }
+}
+impl<Call: Codec + Sync + Send, Extra> traits::Extrinsic for TestXt<Call, Extra> {
+	type Call = Call;
+	type SignaturePayload = (u64, Extra);
+
+	fn is_signed(&self) -> Option<bool> {
+		Some(self.0.is_some())
+	}
+
+	fn new(c: Call, sig: Option<Self::SignaturePayload>) -> Option<Self> {
+		Some(TestXt(sig, c))
+	}
+}
+
+impl<Origin, Call, Extra, Info> Applyable for TestXt<Call, Extra> where
+	Call: 'static + Sized + Send + Sync + Clone + Eq + Codec + Debug + Dispatchable<Origin=Origin>,
+	Extra: SignedExtension<AccountId=u64, Call=Call, DispatchInfo=Info>,
+	Origin: From<Option<u64>>,
+	Info: Clone,
+{
+	type AccountId = u64;
+	type Call = Call;
+	type DispatchInfo = Info;
+
+	fn sender(&self) -> Option<&Self::AccountId> { self.0.as_ref().map(|x| &x.0) }
+
+	/// Checks to see if this is a valid *transaction*. It returns information on it if so.
+	#[allow(deprecated)] // Allow ValidateUnsigned
+	fn validate<U: ValidateUnsigned<Call=Self::Call>>(
+		&self,
+		_info: Self::DispatchInfo,
+		_len: usize,
+	) -> TransactionValidity {
+		Ok(Default::default())
+	}
+
+	/// Executes all necessary logic needed prior to dispatch and deconstructs into function call,
+	/// index and sender.
+	#[allow(deprecated)] // Allow ValidateUnsigned
+	fn apply<U: ValidateUnsigned<Call=Self::Call>>(
+		self,
+		info: Self::DispatchInfo,
+		len: usize,
+	) -> ApplyExtrinsicResult {
+		let maybe_who = if let Some((who, extra)) = self.0 {
+			Extra::pre_dispatch(extra, &who, &self.1, info, len)?;
+			Some(who)
+		} else {
+			Extra::pre_dispatch_unsigned(&self.1, info, len)?;
+			None
+		};
+
+		Ok(self.1.dispatch(maybe_who.into()).map_err(Into::into))
+	}
+}

substrate/primitives/runtime/src/transaction_validity.rs

@@ -0,0 +1,247 @@
+// Copyright 2017-2019 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/>.
+
+//! Transaction validity interface.
+
+use rstd::prelude::*;
+use crate::codec::{Encode, Decode};
+use crate::RuntimeDebug;
+
+/// Priority for a transaction. Additive. Higher is better.
+pub type TransactionPriority = u64;
+
+/// Minimum number of blocks a transaction will remain valid for.
+/// `TransactionLongevity::max_value()` means "forever".
+pub type TransactionLongevity = u64;
+
+/// Tag for a transaction. No two transactions with the same tag should be placed on-chain.
+pub type TransactionTag = Vec<u8>;
+
+/// An invalid transaction validity.
+#[derive(Clone, PartialEq, Eq, Encode, Decode, Copy, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(serde::Serialize))]
+pub enum InvalidTransaction {
+	/// The call of the transaction is not expected.
+	Call,
+	/// General error to do with the inability to pay some fees (e.g. account balance too low).
+	Payment,
+	/// General error to do with the transaction not yet being valid (e.g. nonce too high).
+	Future,
+	/// General error to do with the transaction being outdated (e.g. nonce too low).
+	Stale,
+	/// General error to do with the transaction's proofs (e.g. signature).
+	BadProof,
+	/// The transaction birth block is ancient.
+	AncientBirthBlock,
+	/// The transaction would exhaust the resources of current block.
+	///
+	/// The transaction might be valid, but there are not enough resources left in the current block.
+	ExhaustsResources,
+	/// Any other custom invalid validity that is not covered by this enum.
+	Custom(u8),
+}
+
+impl InvalidTransaction {
+	/// Returns if the reason for the invalidity was block resource exhaustion.
+	pub fn exhausted_resources(&self) -> bool {
+		match self {
+			Self::ExhaustsResources => true,
+			_ => false,
+		}
+	}
+}
+
+impl From<InvalidTransaction> for &'static str {
+	fn from(invalid: InvalidTransaction) -> &'static str {
+		match invalid {
+			InvalidTransaction::Call => "Transaction call is not expected",
+			InvalidTransaction::Future => "Transaction will be valid in the future",
+			InvalidTransaction::Stale => "Transaction is outdated",
+			InvalidTransaction::BadProof => "Transaction has a bad signature",
+			InvalidTransaction::AncientBirthBlock => "Transaction has an ancient birth block",
+			InvalidTransaction::ExhaustsResources =>
+				"Transaction would exhausts the block limits",
+			InvalidTransaction::Payment =>
+				"Inability to pay some fees (e.g. account balance too low)",
+			InvalidTransaction::Custom(_) => "InvalidTransaction custom error",
+		}
+	}
+}
+
+/// An unknown transaction validity.
+#[derive(Clone, PartialEq, Eq, Encode, Decode, Copy, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(serde::Serialize))]
+pub enum UnknownTransaction {
+	/// Could not lookup some information that is required to validate the transaction.
+	CannotLookup,
+	/// No validator found for the given unsigned transaction.
+	NoUnsignedValidator,
+	/// Any other custom unknown validity that is not covered by this enum.
+	Custom(u8),
+}
+
+impl From<UnknownTransaction> for &'static str {
+	fn from(unknown: UnknownTransaction) -> &'static str {
+		match unknown {
+			UnknownTransaction::CannotLookup =>
+				"Could not lookup information required to validate the transaction",
+			UnknownTransaction::NoUnsignedValidator =>
+				"Could not find an unsigned validator for the unsigned transaction",
+			UnknownTransaction::Custom(_) => "UnknownTransaction custom error",
+		}
+	}
+}
+
+/// Errors that can occur while checking the validity of a transaction.
+#[derive(Clone, PartialEq, Eq, Encode, Decode, Copy, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(serde::Serialize))]
+pub enum TransactionValidityError {
+	/// The transaction is invalid.
+	Invalid(InvalidTransaction),
+	/// Transaction validity can't be determined.
+	Unknown(UnknownTransaction),
+}
+
+impl TransactionValidityError {
+	/// Returns `true` if the reason for the error was block resource exhaustion.
+	pub fn exhausted_resources(&self) -> bool {
+		match self {
+			Self::Invalid(e) => e.exhausted_resources(),
+			Self::Unknown(_) => false,
+		}
+	}
+}
+
+impl From<TransactionValidityError> for &'static str {
+	fn from(err: TransactionValidityError) -> &'static str {
+		match err {
+			TransactionValidityError::Invalid(invalid) => invalid.into(),
+			TransactionValidityError::Unknown(unknown) => unknown.into(),
+		}
+	}
+}
+
+impl From<InvalidTransaction> for TransactionValidityError {
+	fn from(err: InvalidTransaction) -> Self {
+		TransactionValidityError::Invalid(err)
+	}
+}
+
+impl From<UnknownTransaction> for TransactionValidityError {
+	fn from(err: UnknownTransaction) -> Self {
+		TransactionValidityError::Unknown(err)
+	}
+}
+
+/// Information on a transaction's validity and, if valid, on how it relates to other transactions.
+pub type TransactionValidity = Result<ValidTransaction, TransactionValidityError>;
+
+impl Into<TransactionValidity> for InvalidTransaction {
+	fn into(self) -> TransactionValidity {
+		Err(self.into())
+	}
+}
+
+impl Into<TransactionValidity> for UnknownTransaction {
+	fn into(self) -> TransactionValidity {
+		Err(self.into())
+	}
+}
+
+/// Information concerning a valid transaction.
+#[derive(Clone, PartialEq, Eq, Encode, Decode, RuntimeDebug)]
+pub struct ValidTransaction {
+	/// Priority of the transaction.
+	///
+	/// Priority determines the ordering of two transactions that have all
+	/// their dependencies (required tags) satisfied.
+	pub priority: TransactionPriority,
+	/// Transaction dependencies
+	///
+	/// A non-empty list signifies that some other transactions which provide
+	/// given tags are required to be included before that one.
+	pub requires: Vec<TransactionTag>,
+	/// Provided tags
+	///
+	/// A list of tags this transaction provides. Successfully importing the transaction
+	/// will enable other transactions that depend on (require) those tags to be included as well.
+	/// Provided and required tags allow Substrate to build a dependency graph of transactions
+	/// and import them in the right (linear) order.
+	pub provides: Vec<TransactionTag>,
+	/// Transaction longevity
+	///
+	/// Longevity describes minimum number of blocks the validity is correct.
+	/// After this period transaction should be removed from the pool or revalidated.
+	pub longevity: TransactionLongevity,
+	/// A flag indicating if the transaction should be propagated to other peers.
+	///
+	/// By setting `false` here the transaction will still be considered for
+	/// including in blocks that are authored on the current node, but will
+	/// never be sent to other peers.
+	pub propagate: bool,
+}
+
+impl Default for ValidTransaction {
+	fn default() -> Self {
+		ValidTransaction {
+			priority: 0,
+			requires: vec![],
+			provides: vec![],
+			longevity: TransactionLongevity::max_value(),
+			propagate: true,
+		}
+	}
+}
+
+impl ValidTransaction {
+	/// Combine two instances into one, as a best effort. This will take the superset of each of the
+	/// `provides` and `requires` tags, it will sum the priorities, take the minimum longevity and
+	/// the logic *And* of the propagate flags.
+	pub fn combine_with(mut self, mut other: ValidTransaction) -> Self {
+		ValidTransaction {
+			priority: self.priority.saturating_add(other.priority),
+			requires: { self.requires.append(&mut other.requires); self.requires },
+			provides: { self.provides.append(&mut other.provides); self.provides },
+			longevity: self.longevity.min(other.longevity),
+			propagate: self.propagate && other.propagate,
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn should_encode_and_decode() {
+		let v: TransactionValidity = Ok(ValidTransaction {
+			priority: 5,
+			requires: vec![vec![1, 2, 3, 4]],
+			provides: vec![vec![4, 5, 6]],
+			longevity: 42,
+			propagate: false,
+		});
+
+		let encoded = v.encode();
+		assert_eq!(
+			encoded,
+			vec![0, 5, 0, 0, 0, 0, 0, 0, 0, 4, 16, 1, 2, 3, 4, 4, 12, 4, 5, 6, 42, 0, 0, 0, 0, 0, 0, 0, 0]
+		);
+
+		// decode back
+		assert_eq!(TransactionValidity::decode(&mut &*encoded), Ok(v));
+	}
+}