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add comments (#806)
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@asiniscalchi
asiniscalchi authored Oct 7, 2024
1 parent cc2054c commit 892d8d9
Showing 1 changed file with 68 additions and 40 deletions.
108 changes: 68 additions & 40 deletions runtime/laos/src/configs/xcm_config.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,58 +40,54 @@ use xcm_builder::{
use xcm_executor::XcmExecutor;

parameter_types! {
// Represents the location of the Relay Chain (parent in the XCM hierarchy).
pub const RelayLocation: Location = Location::parent();
// Optional network identifier for the Relay Chain; set to `None` for default behavior.
pub const RelayNetwork: Option<NetworkId> = None;
// Defines the origin for messages coming from the Relay Chain.
pub RelayChainOrigin: RuntimeOrigin = cumulus_pallet_xcm::Origin::Relay.into();
// For the real deployment, it is recommended to set `RelayNetwork` according to the relay chain
// and prepend `UniversalLocation` with `GlobalConsensus(RelayNetwork::get())`.
// Universal location for the parachain in the network topology.
// For production, consider setting `RelayNetwork` and using `GlobalConsensus`.
pub UniversalLocation: InteriorLocation = Parachain(ParachainInfo::parachain_id().into()).into();
}

/// Type for specifying how a `MultiLocation` can be converted into an `AccountId`. This is used
/// when determining ownership of accounts for asset transacting and when attempting to use XCM
/// `Transact` in order to determine the dispatch Origin.
/// Converts a `MultiLocation` into an `AccountId`.
/// Used for asset ownership and dispatching `Transact` instructions.
pub type LocationToAccountId = (
// The parent (Relay-chain) origin converts to the parent `AccountId`.
// Converts the parent (Relay Chain) location into the parent `AccountId`.
ParentIsPreset<AccountId>,
// Sibling parachain origins convert to AccountId via the `ParaId::into`.
// Converts sibling parachain locations into `AccountId` via `ParaId::into()`.
SiblingParachainConvertsVia<Sibling, AccountId>,
// Straight up local `AccountId20` origins just alias directly to `AccountId`.
// Directly aliases `AccountId20` locations to the local `AccountId`.
AccountKey20Aliases<RelayNetwork, AccountId>,
);

/// Means for transacting assets on this chain.
/// Handles asset transactions on this chain.
pub type LocalAssetTransactor = FungibleAdapter<
// Use this currency:
// Uses the Balances pallet as the fungible asset handler.
Balances,
// Use this currency when it is a fungible asset matching the given location or name:
// Recognizes assets that are concrete representations of the Relay Chain's location.
IsConcrete<RelayLocation>,
// Do a simple pun to convert an AccountId20 Location into a native chain account ID:
// Converts `MultiLocation` into local `AccountId` for asset operations.
LocationToAccountId,
// Our chain's account ID type (we can't get away without mentioning it explicitly):
// Specifies the local `AccountId` type.
AccountId,
// We don't track any teleports.
// Teleportation of assets is not tracked or allowed.
(),
>;

/// This is the type we use to convert an (incoming) XCM origin into a local `Origin` instance,
/// ready for dispatching a transaction with Xcm's `Transact`. There is an `OriginKind` which can
/// biases the kind of local `Origin` it will become.
/// Converts incoming XCM origins into local `Origin` instances for dispatching transactions.
pub type XcmOriginToTransactDispatchOrigin = (
// Sovereign account converter; this attempts to derive an `AccountId` from the origin location
// using `LocationToAccountId` and then turn that into the usual `Signed` origin. Useful for
// foreign chains who want to have a local sovereign account on this chain which they control.
// Converts a sovereign account from the origin location into a local `Signed` origin.
SovereignSignedViaLocation<LocationToAccountId, RuntimeOrigin>,
// Native converter for Relay-chain (Parent) location; will convert to a `Relay` origin when
// recognized.
// Converts the Relay Chain (Parent) location into a native `Relay` origin.
RelayChainAsNative<RelayChainOrigin, RuntimeOrigin>,
// Native converter for sibling Parachains; will convert to a `SiblingPara` origin when
// recognized.
// Converts sibling parachain locations into a native `SiblingParachain` origin.
SiblingParachainAsNative<cumulus_pallet_xcm::Origin, RuntimeOrigin>,
// Native signed account converter; this just converts an `AccountId20` origin into a normal
// `RuntimeOrigin::Signed` origin of the same 20-byte value.
// Converts `AccountId20` from the origin into a local `Signed` origin with the same 20-byte
// key.
SignedAccountKey20AsNative<RelayNetwork, RuntimeOrigin>,
// Xcm origins can be represented natively under the Xcm pallet's Xcm origin.
// Passes through XCM origins as native XCM pallet origins.
XcmPassthrough<RuntimeOrigin>,
);

Expand All @@ -102,26 +98,41 @@ parameter_types! {
pub const MaxAssetsIntoHolding: u32 = 64;
}

// Defines a struct representing either the Parent (Relay Chain) or its Executive plurality.
pub struct ParentOrParentsExecutivePlurality;
impl Contains<Location> for ParentOrParentsExecutivePlurality {
fn contains(location: &Location) -> bool {
matches!(location.unpack(), (1, []) | (1, [Plurality { id: BodyId::Executive, .. }]))
// Checks if the location matches either:
// - The Parent location (Relay Chain).
// - The Executive body of the Parent.
matches!(
location.unpack(),
(1, []) // Matches the Parent location.
| (1, [Plurality { id: BodyId::Executive, .. }]) /* Matches Parent's
* Executive plurality. */
)
}
}

pub type Barrier = TrailingSetTopicAsId<
// Converts trailing topics into IDs for message tracking.
DenyThenTry<
DenyReserveTransferToRelayChain,
// Denies specific operations first, then tries others if denied.
DenyReserveTransferToRelayChain, /* Denies reserve asset transfers to the Relay Chain
* for security reasons. */
(
TakeWeightCredit,
TakeWeightCredit, // Consumes the weight credit from the XCM message.
WithComputedOrigin<
// Computes the execution origin for authorization.
(
// Allows paid execution from any top-level XCM origin.
AllowTopLevelPaidExecutionFrom<Everything>,
// Allows free execution (unpaid) from the parent or its executive plurality.
AllowExplicitUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
// ^^^ Parent and its exec plurality get free execution
// ^^^ Parent and its executive plurality get free execution.
),
UniversalLocation,
ConstU32<8>,
UniversalLocation, // Universal location used for origin matching.
ConstU32<8>, // Maximum depth for recursive origin resolution.
>,
),
>,
Expand All @@ -131,21 +142,27 @@ pub struct XcmConfig;
impl xcm_executor::Config for XcmConfig {
type RuntimeCall = RuntimeCall;
type XcmSender = XcmRouter;
// How to withdraw and deposit an asset.
// Handles asset operations like deposit and withdrawal.
type AssetTransactor = LocalAssetTransactor;
// Converts XCM origins to local dispatch origins.
type OriginConverter = XcmOriginToTransactDispatchOrigin;
// Identifies which assets are considered reserve assets.
type IsReserve = NativeAsset;
type IsTeleporter = (); // Teleporting is disabled.
type UniversalLocation = UniversalLocation;
// Filters and allows XCM messages based on security policies.
type Barrier = Barrier;
// Calculates the weight (execution cost) of XCM messages.
type Weigher = FixedWeightBounds<UnitWeightCost, RuntimeCall, MaxInstructions>;
// Converts weight fees into asset payments and handles fee charging.
type Trader = UsingComponents<
<Runtime as pallet_transaction_payment::Config>::WeightToFee,
RelayLocation,
AccountId,
Balances,
ToAuthor<Runtime>,
>;
// Handles responses from XCM messages.
type ResponseHandler = PolkadotXcm;
type AssetTrap = PolkadotXcm;
type AssetClaims = PolkadotXcm;
Expand All @@ -158,48 +175,55 @@ impl xcm_executor::Config for XcmConfig {
type MessageExporter = ();
type UniversalAliases = Nothing;
type CallDispatcher = RuntimeCall;
// Allows all calls to be dispatched via XCM.
type SafeCallFilter = Everything;
type Aliasers = Nothing;
// Ensures transactional integrity during XCM execution.
type TransactionalProcessor = FrameTransactionalProcessor;
type HrmpNewChannelOpenRequestHandler = ();
type HrmpChannelAcceptedHandler = ();
type HrmpChannelClosingHandler = ();
}

/// No local origins on this chain are allowed to dispatch XCM sends/executions.
/// Disallows local origins from dispatching XCM sends/executions.
pub type LocalOriginToLocation = SignedToAccountId20<RuntimeOrigin, AccountId, RelayNetwork>;

/// The means for routing XCM messages which are not for local execution into the right message
/// queues.
/// Routes XCM messages to the appropriate message queues.
pub type XcmRouter = xcm_builder::WithUniqueTopic<(
// Two routers - use UMP to communicate with the relay chain:
// Uses UMP (Upward Message Passing) to communicate with the Relay Chain (Parent).
cumulus_primitives_utility::ParentAsUmp<crate::ParachainSystem, (), ()>,
// ..and XCMP to communicate with the sibling chains.
// Uses XCMP (Cross-Chain Message Passing) to communicate with sibling parachains.
crate::XcmpQueue,
)>;

impl pallet_xcm::Config for Runtime {
type RuntimeEvent = RuntimeEvent;
// Determines which origins are allowed to send XCM messages.
type SendXcmOrigin = EnsureXcmOrigin<RuntimeOrigin, LocalOriginToLocation>;
type XcmRouter = XcmRouter;
// Determines which origins are allowed to execute XCM messages.
type ExecuteXcmOrigin = EnsureXcmOrigin<RuntimeOrigin, LocalOriginToLocation>;
type XcmExecuteFilter = Nothing;
type XcmExecutor = XcmExecutor<XcmConfig>;
type XcmTeleportFilter = Nothing;
// Allows all reserve asset transfers.
type XcmReserveTransferFilter = Everything;
// Calculates the weight of XCM messages.
type Weigher = FixedWeightBounds<UnitWeightCost, RuntimeCall, MaxInstructions>;
type UniversalLocation = UniversalLocation;
type RuntimeOrigin = RuntimeOrigin;
type RuntimeCall = RuntimeCall;
const VERSION_DISCOVERY_QUEUE_SIZE: u32 = 100;
// ^ Override for AdvertisedXcmVersion default
// ^ Overrides the default size for version discovery queue.
type AdvertisedXcmVersion = pallet_xcm::CurrentXcmVersion;
type Currency = Balances;
type CurrencyMatcher = ();
type TrustedLockers = ();
// Converts `MultiLocation` to local `AccountId`.
type SovereignAccountOf = LocationToAccountId;
type MaxLockers = ConstU32<8>;
type WeightInfo = pallet_xcm::TestWeightInfo;
// Only the root account has administrative privileges.
type AdminOrigin = EnsureRoot<AccountId>;
type MaxRemoteLockConsumers = ConstU32<0>;
type RemoteLockConsumerIdentifier = ();
Expand All @@ -210,9 +234,11 @@ impl cumulus_pallet_xcm::Config for Runtime {
type XcmExecutor = XcmExecutor<XcmConfig>;
}

/// Converts a local `Signed` origin into a `MultiLocation` using `AccountId20`.
pub struct SignedToAccountId20<RuntimeOrigin, AccountId, Network>(
PhantomData<(RuntimeOrigin, AccountId, Network)>,
);

impl<
RuntimeOrigin: OriginTrait + Clone,
AccountId: Into<[u8; 20]>,
Expand All @@ -224,6 +250,8 @@ where
{
fn try_convert(o: RuntimeOrigin) -> Result<Location, RuntimeOrigin> {
o.try_with_caller(|caller| match caller.try_into() {
// Converts a `Signed` origin into a `MultiLocation::AccountKey20` with the same account
// key.
Ok(SystemRawOrigin::Signed(who)) =>
Ok(Junction::AccountKey20 { network: Network::get(), key: who.into() }.into()),
Ok(other) => Err(other.into()),
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