Unverified Commit 669a6edf authored by Gavin Wood's avatar Gavin Wood Committed by GitHub
Browse files

Introduce plurality XCM locations (#2846)

* Introduce plurality XCM locations

* Add RelayedFrom
parent e4f5ade5
Pipeline #133424 failed with stages
in 20 minutes and 20 seconds
......@@ -32,6 +32,41 @@ pub enum NetworkId {
Kusama,
}
/// An identifier of a pluralistic body.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Encode, Decode, Debug)]
pub enum BodyId {
/// The only body in its context.
Unit,
/// A named body.
Named(Vec<u8>),
/// An indexed body.
// TODO: parity-scale-codec#262: Change to be a tuple.
Index { #[codec(compact)] id: u32 },
/// The unambiguous executive body (for Polkadot, this would be the Polkadot council).
Executive,
/// The unambiguous technical body (for Polkadot, this would be the Technical Committee).
Technical,
/// The unambiguous legislative body (for Polkadot, this could be considered the opinion of a majority of
/// lock-voters).
Legislative,
/// The unambiguous judicial body (this doesn't exist on Polkadot, but if it were to get a "grand oracle", it
/// may be considered as that).
Judicial,
}
/// A part of a pluralistic body.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Encode, Decode, Debug)]
pub enum BodyPart {
/// The body's declaration, under whatever means it decides.
Voice,
/// A given number of members of the body.
Members { #[codec(compact)] count: u32 },
/// No less than the given proportion of members of the body.
AtLeastProportion { #[codec(compact)] nom: u32, #[codec(compact)] denom: u32 },
/// More than than the given proportion of members of the body.
MoreThanProportion { #[codec(compact)] nom: u32, #[codec(compact)] denom: u32 },
}
/// 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.
......@@ -85,21 +120,30 @@ pub enum Junction {
///
/// Not currently used except as a fallback when deriving ancestry.
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 },
}
impl Junction {
pub fn is_sub_consensus(&self) -> bool {
/// Returns true if this junction can be considered an interior part of its context. This is generally `true`,
/// except for the `Parent` item.
pub fn is_interior(&self) -> bool {
match self {
Junction::Parent => false,
Junction::Parachain { .. } |
Junction::AccountId32 { .. } |
Junction::AccountIndex64 { .. } |
Junction::AccountKey20 { .. } |
Junction::PalletInstance { .. } |
Junction::GeneralIndex { .. } |
Junction::GeneralKey(..) |
Junction::OnlyChild => true,
Junction::Parachain { .. }
| Junction::AccountId32 { .. }
| Junction::AccountIndex64 { .. }
| Junction::AccountKey20 { .. }
| Junction::PalletInstance { .. }
| Junction::GeneralIndex { .. }
| Junction::GeneralKey(..)
| Junction::OnlyChild
| Junction::Plurality { .. }
=> true,
}
}
}
......@@ -227,6 +227,20 @@ pub enum Xcm<Call> {
#[codec(compact)] sender: u32,
#[codec(compact)] recipient: u32,
},
/// A message to indicate that the embedded XCM is actually arriving on behalf of some consensus
/// location within the origin.
///
/// Safety: No concerns.
///
/// Kind: *Instruction*
///
/// Errors:
#[codec(index = 10)]
RelayedFrom {
who: MultiLocation,
message: alloc::boxed::Box<Xcm<Call>>,
},
}
impl<Call> From<Xcm<Call>> for VersionedXcm<Call> {
......@@ -268,7 +282,9 @@ impl<Call> Xcm<Call> {
HrmpChannelClosing { initiator, sender, recipient}
=> HrmpChannelClosing { initiator, sender, recipient},
Transact { origin_type, require_weight_at_most, call}
=> Transact { origin_type, require_weight_at_most, call: call.into() }
=> Transact { origin_type, require_weight_at_most, call: call.into() },
RelayedFrom { who, message }
=> RelayedFrom { who, message: alloc::boxed::Box::new((*message).into()) },
}
}
}
......
......@@ -539,6 +539,23 @@ impl MultiLocation {
}
}
/// Mutate `self` so that it is suffixed with `prefix`. The correct normalised form is returned, removing any
/// internal `Parent`s.
///
/// Does not modify `self` and returns `Err` with `prefix` in case of overflow.
pub fn append_with(&mut self, suffix: MultiLocation) -> Result<(), MultiLocation> {
let mut prefix = suffix;
core::mem::swap(self, &mut prefix);
match self.prepend_with(prefix) {
Ok(()) => Ok(()),
Err(prefix) => {
let mut suffix = prefix;
core::mem::swap(self, &mut suffix);
Err(suffix)
}
}
}
/// Mutate `self` so that it is prefixed with `prefix`. The correct normalised form is returned, removing any
/// internal `Parent`s.
///
......@@ -566,6 +583,12 @@ impl MultiLocation {
}
Ok(())
}
/// Returns true iff `self` is an interior location. For this it may not contain any `Junction`s for which
/// `Junction::is_interior` returns `false`. This
pub fn is_interior(&self) -> bool {
self.iter().all(Junction::is_interior)
}
}
impl From<MultiLocation> for VersionedMultiLocation {
......
......@@ -182,6 +182,14 @@ impl<Config: config::Config> XcmExecutor<Config> {
Config::ResponseHandler::on_response(origin, query_id, response);
None
}
(origin, Xcm::RelayedFrom { who, message }) => {
ensure!(who.is_interior(), XcmError::EscalationOfPrivilege);
let mut origin = origin;
origin.append_with(who).map_err(|_| XcmError::MultiLocationFull)?;
let surplus = Self::do_execute_xcm(origin, top_level, *message, weight_credit, None, trader)?;
total_surplus = total_surplus.saturating_add(surplus);
None
}
_ => Err(XcmError::UnhandledXcmMessage)?, // Unhandled XCM message.
};
......
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