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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot 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.
// Polkadot 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 Polkadot. If not, see <http://www.gnu.org/licenses/>.
//! Support data structures for `Location`, primarily the `Junction` datatype.
use super::Location;
pub use crate::v4::{BodyId, BodyPart};
use crate::{
v4::{Junction as OldJunction, NetworkId as OldNetworkId},
VersionedLocation,
};
use bounded_collections::{BoundedSlice, BoundedVec, ConstU32};
use codec::{self, Decode, Encode, MaxEncodedLen};
use hex_literal::hex;
use scale_info::TypeInfo;
use serde::{Deserialize, Serialize};
/// A single item in a path to describe the relative location of a consensus system.
///
/// Each item assumes a pre-existing location as its context and is defined in terms of it.
#[derive(
Copy,
Clone,
Eq,
PartialEq,
Ord,
PartialOrd,
Encode,
Decode,
Debug,
TypeInfo,
MaxEncodedLen,
Serialize,
Deserialize,
)]
pub enum Junction {
/// An indexed parachain belonging to and operated by the context.
///
/// Generally used when the context is a Polkadot Relay-chain.
Parachain(#[codec(compact)] u32),
/// A 32-byte identifier for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// Generally used when the context is a Substrate-based chain.
AccountId32 { network: Option<NetworkId>, id: [u8; 32] },
/// An 8-byte index for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// May be used when the context is a Frame-based chain and includes e.g. an indices pallet.
AccountIndex64 {
network: Option<NetworkId>,
#[codec(compact)]
index: u64,
},
/// A 20-byte identifier for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// May be used when the context is an Ethereum or Bitcoin chain or smart-contract.
AccountKey20 { network: Option<NetworkId>, key: [u8; 20] },
/// An instanced, indexed pallet that forms a constituent part of the context.
///
/// Generally used when the context is a Frame-based chain.
PalletInstance(u8),
/// A non-descript index within the context location.
///
/// Usage will vary widely owing to its generality.
///
/// NOTE: Try to avoid using this and instead use a more specific item.
GeneralIndex(#[codec(compact)] u128),
/// A nondescript array datum, 32 bytes, acting as a key within the context
/// location.
///
/// Usage will vary widely owing to its generality.
///
/// NOTE: Try to avoid using this and instead use a more specific item.
// Note this is implemented as an array with a length rather than using `BoundedVec` owing to
// the bound for `Copy`.
GeneralKey { length: u8, data: [u8; 32] },
/// The unambiguous child.
///
/// Not currently used except as a fallback when deriving context.
OnlyChild,
/// A pluralistic body existing within consensus.
///
/// Typical to be used to represent a governance origin of a chain, but could in principle be
/// used to represent things such as multisigs also.
Plurality { id: BodyId, part: BodyPart },
/// A global network capable of externalizing its own consensus. This is not generally
/// meaningful outside of the universal level.
GlobalConsensus(NetworkId),
}
/// The genesis hash of the Westend testnet. Used to identify it.
pub const WESTEND_GENESIS_HASH: [u8; 32] =
hex!["e143f23803ac50e8f6f8e62695d1ce9e4e1d68aa36c1cd2cfd15340213f3423e"];
/// The genesis hash of the Rococo testnet. Used to identify it.
pub const ROCOCO_GENESIS_HASH: [u8; 32] =
hex!["6408de7737c59c238890533af25896a2c20608d8b380bb01029acb392781063e"];
/// Dummy genesis hash used instead of defunct networks like Wococo (and soon Rococo).
pub const DUMMY_GENESIS_HASH: [u8; 32] = [0; 32];
/// A global identifier of a data structure existing within consensus.
///
/// Maintenance note: Networks with global consensus and which are practically bridgeable within the
/// Polkadot ecosystem are given preference over explicit naming in this enumeration.
#[derive(
Copy,
Clone,
Eq,
PartialEq,
Ord,
PartialOrd,
Encode,
Decode,
Debug,
TypeInfo,
MaxEncodedLen,
Serialize,
Deserialize,
)]
pub enum NetworkId {
/// Network specified by the first 32 bytes of its genesis block.
ByGenesis([u8; 32]),
/// Network defined by the first 32-bytes of the hash and number of some block it contains.
ByFork { block_number: u64, block_hash: [u8; 32] },
/// The Polkadot mainnet Relay-chain.
Polkadot,
/// The Kusama canary-net Relay-chain.
Kusama,
/// An Ethereum network specified by its chain ID.
Ethereum {
/// The EIP-155 chain ID.
#[codec(compact)]
chain_id: u64,
},
/// The Bitcoin network, including hard-forks supported by Bitcoin Core development team.
BitcoinCore,
/// The Bitcoin network, including hard-forks supported by Bitcoin Cash developers.
BitcoinCash,
/// The Polkadot Bulletin chain.
PolkadotBulletin,
}
impl From<OldNetworkId> for Option<NetworkId> {
fn from(old: OldNetworkId) -> Self {
Some(NetworkId::from(old))
}
}
impl From<OldNetworkId> for NetworkId {
fn from(old: OldNetworkId) -> Self {
use OldNetworkId::*;
match old {
ByGenesis(hash) => Self::ByGenesis(hash),
ByFork { block_number, block_hash } => Self::ByFork { block_number, block_hash },
Polkadot => Self::Polkadot,
Kusama => Self::Kusama,
Westend => Self::ByGenesis(WESTEND_GENESIS_HASH),
Rococo => Self::ByGenesis(ROCOCO_GENESIS_HASH),
Wococo => Self::ByGenesis(DUMMY_GENESIS_HASH),
Ethereum { chain_id } => Self::Ethereum { chain_id },
BitcoinCore => Self::BitcoinCore,
BitcoinCash => Self::BitcoinCash,
PolkadotBulletin => Self::PolkadotBulletin,
}
}
}
impl From<NetworkId> for Junction {
fn from(n: NetworkId) -> Self {
Self::GlobalConsensus(n)
}
}
impl From<[u8; 32]> for Junction {
fn from(id: [u8; 32]) -> Self {
Self::AccountId32 { network: None, id }
}
}
impl From<BoundedVec<u8, ConstU32<32>>> for Junction {
fn from(key: BoundedVec<u8, ConstU32<32>>) -> Self {
key.as_bounded_slice().into()
}
}
impl<'a> From<BoundedSlice<'a, u8, ConstU32<32>>> for Junction {
fn from(key: BoundedSlice<'a, u8, ConstU32<32>>) -> Self {
let mut data = [0u8; 32];
data[..key.len()].copy_from_slice(&key[..]);
Self::GeneralKey { length: key.len() as u8, data }
}
}
impl<'a> TryFrom<&'a Junction> for BoundedSlice<'a, u8, ConstU32<32>> {
type Error = ();
fn try_from(key: &'a Junction) -> Result<Self, ()> {
match key {
Junction::GeneralKey { length, data } =>
BoundedSlice::try_from(&data[..data.len().min(*length as usize)]).map_err(|_| ()),
_ => Err(()),
}
}
}
impl From<[u8; 20]> for Junction {
fn from(key: [u8; 20]) -> Self {
Self::AccountKey20 { network: None, key }
}
}
impl From<u64> for Junction {
fn from(index: u64) -> Self {
Self::AccountIndex64 { network: None, index }
}
}
impl From<u128> for Junction {
fn from(id: u128) -> Self {
Self::GeneralIndex(id)
}
}
impl TryFrom<OldJunction> for Junction {
type Error = ();
fn try_from(value: OldJunction) -> Result<Self, ()> {
use OldJunction::*;
Ok(match value {
Parachain(id) => Self::Parachain(id),
AccountId32 { network: maybe_network, id } =>
Self::AccountId32 { network: maybe_network.map(|network| network.into()), id },
AccountIndex64 { network: maybe_network, index } =>
Self::AccountIndex64 { network: maybe_network.map(|network| network.into()), index },
AccountKey20 { network: maybe_network, key } =>
Self::AccountKey20 { network: maybe_network.map(|network| network.into()), key },
PalletInstance(index) => Self::PalletInstance(index),
GeneralIndex(id) => Self::GeneralIndex(id),
GeneralKey { length, data } => Self::GeneralKey { length, data },
OnlyChild => Self::OnlyChild,
Plurality { id, part } => Self::Plurality { id, part },
GlobalConsensus(network) => Self::GlobalConsensus(network.into()),
})
}
}
impl Junction {
/// Convert `self` into a `Location` containing 0 parents.
///
/// Similar to `Into::into`, except that this method can be used in a const evaluation context.
pub fn into_location(self) -> Location {
Location::new(0, [self])
}
/// Convert `self` into a `Location` containing `n` parents.
///
/// Similar to `Self::into_location`, with the added ability to specify the number of parent
/// junctions.
pub fn into_exterior(self, n: u8) -> Location {
Location::new(n, [self])
}
/// Convert `self` into a `VersionedLocation` containing 0 parents.
///
/// Similar to `Into::into`, except that this method can be used in a const evaluation context.
pub fn into_versioned(self) -> VersionedLocation {
self.into_location().into_versioned()
}
/// Remove the `NetworkId` value.
pub fn remove_network_id(&mut self) {
use Junction::*;
match self {
AccountId32 { ref mut network, .. } |
AccountIndex64 { ref mut network, .. } |
AccountKey20 { ref mut network, .. } => *network = None,
_ => {},
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use alloc::vec;
#[test]
fn junction_round_trip_works() {
let j = Junction::GeneralKey { length: 32, data: [1u8; 32] };
let k = Junction::try_from(OldJunction::try_from(j).unwrap()).unwrap();
assert_eq!(j, k);
let j = OldJunction::GeneralKey { length: 32, data: [1u8; 32] };
let k = OldJunction::try_from(Junction::try_from(j).unwrap()).unwrap();
assert_eq!(j, k);
let j = Junction::from(BoundedVec::try_from(vec![1u8, 2, 3, 4]).unwrap());
let k = Junction::try_from(OldJunction::try_from(j).unwrap()).unwrap();
assert_eq!(j, k);
let s: BoundedSlice<_, _> = (&k).try_into().unwrap();
assert_eq!(s, &[1u8, 2, 3, 4][..]);
let j = OldJunction::GeneralKey { length: 32, data: [1u8; 32] };
let k = OldJunction::try_from(Junction::try_from(j).unwrap()).unwrap();
assert_eq!(j, k);
}
}