Struct frame_metadata_hash_extension::CheckMetadataHash

pub struct CheckMetadataHash<T> { /* private fields */ }

Extension for optionally verifying the metadata hash.

The metadata hash is cryptographical representation of the runtime metadata. This metadata hash is build as described in RFC78. This metadata hash should give users the confidence that what they build with an online wallet is the same they are signing with their offline wallet and then applying on chain. To ensure that the online wallet is not tricking the offline wallet into decoding and showing an incorrect extrinsic, the offline wallet will include the metadata hash into the additional signed data and the runtime will then do the same. If the metadata hash doesn’t match, the signature verification will fail and thus, the transaction will be rejected. The RFC contains more details on how it works.

The extension adds one byte (the mode) to the size of the extrinsic. This one byte is controlling if the metadata hash should be added to the signed data or not. Mode 0 means that the metadata hash is not added and thus, None is added to the signed data. Mode 1 means that the metadata hash is added and thus, Some(metadata_hash) is added to the signed data. Further values of mode are reserved for future changes.

The metadata hash is read from the environment variable RUNTIME_METADATA_HASH. This environment variable is for example set by the substrate-wasm-builder when the feature for generating the metadata hash is enabled. If the environment variable is not set and mode = 1 is passed, the transaction is rejected with UnknownTransaction::CannotLookup.

Implementations

impl<T> CheckMetadataHash<T>

pub fn new(enable: bool) -> Self

Creates new SignedExtension to check metadata hash.

pub fn new_with_custom_hash(metadata_hash: [u8; 32]) -> Self

Create an instance that uses the given metadata_hash.

This is useful for testing the extension.

Trait Implementations

impl<T: Clone> Clone for CheckMetadataHash<T>

fn clone(&self) -> CheckMetadataHash<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for CheckMetadataHash<T>

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Decode for CheckMetadataHash<T>

where PhantomData<T>: Decode,

fn decode<__CodecInputEdqy: Input>( __codec_input_edqy: &mut __CodecInputEdqy, ) -> Result<Self, Error>

Attempt to deserialise the value from input.

fn decode_into<I>( input: &mut I, dst: &mut MaybeUninit<Self>, ) -> Result<DecodeFinished, Error>

where I: Input,

Attempt to deserialize the value from input into a pre-allocated piece of memory.

fn skip<I>(input: &mut I) -> Result<(), Error>

where I: Input,

Attempt to skip the encoded value from input.

fn encoded_fixed_size() -> Option<usize>

Returns the fixed encoded size of the type.

impl<T> Encode for CheckMetadataHash<T>

where PhantomData<T>: Encode,

fn size_hint(&self) -> usize

If possible give a hint of expected size of the encoding.

fn encode_to<__CodecOutputEdqy: Output + ?Sized>( &self, __codec_dest_edqy: &mut __CodecOutputEdqy, )

Convert self to a slice and append it to the destination.

fn encode(&self) -> Vec<u8>

Convert self to an owned vector.

fn using_encoded<R, F>(&self, f: F) -> R

where F: FnOnce(&[u8]) -> R,

Convert self to a slice and then invoke the given closure with it.

fn encoded_size(&self) -> usize

Calculates the encoded size.

impl<T: PartialEq> PartialEq for CheckMetadataHash<T>

fn eq(&self, other: &CheckMetadataHash<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: Config + Send + Sync> SignedExtension for CheckMetadataHash<T>

type AccountId = <T as Config>::AccountId

The type which encodes the sender identity.

type Call = <T as Config>::RuntimeCall

The type which encodes the call to be dispatched.

type AdditionalSigned = Option<[u8; 32]>

Any additional data that will go into the signed payload. This may be created dynamically from the transaction using the additional_signed function.

type Pre = ()

The type that encodes information that can be passed from pre_dispatch to post-dispatch.

const IDENTIFIER: &'static str = "CheckMetadataHash"

Unique identifier of this signed extension.

fn additional_signed( &self, ) -> Result<Self::AdditionalSigned, TransactionValidityError>

Construct any additional data that should be in the signed payload of the transaction. Can also perform any pre-signature-verification checks and return an error if needed.

fn pre_dispatch( self, who: &Self::AccountId, call: &Self::Call, info: &DispatchInfoOf<Self::Call>, len: usize, ) -> Result<Self::Pre, TransactionValidityError>

Do any pre-flight stuff for a signed transaction.

fn validate( &self, _who: &Self::AccountId, _call: &Self::Call, _info: &<Self::Call as Dispatchable>::Info, _len: usize, ) -> Result<ValidTransaction, TransactionValidityError>

Validate a signed transaction for the transaction queue.

fn validate_unsigned( _call: &Self::Call, _info: &<Self::Call as Dispatchable>::Info, _len: usize, ) -> Result<ValidTransaction, TransactionValidityError>

Validate an unsigned transaction for the transaction queue.

fn pre_dispatch_unsigned( call: &Self::Call, info: &<Self::Call as Dispatchable>::Info, len: usize, ) -> Result<(), TransactionValidityError>

Do any pre-flight stuff for a unsigned transaction.

fn post_dispatch( _pre: Option<Self::Pre>, _info: &<Self::Call as Dispatchable>::Info, _post_info: &<Self::Call as Dispatchable>::PostInfo, _len: usize, _result: &Result<(), DispatchError>, ) -> Result<(), TransactionValidityError>

Do any post-flight stuff for an extrinsic.

fn metadata() -> Vec<SignedExtensionMetadata>

Returns the metadata for this signed extension.

impl<T> TypeInfo for CheckMetadataHash<T>

where PhantomData<T>: TypeInfo + 'static, T: 'static,

type Identity = CheckMetadataHash<T>

The type identifying for which type info is provided.

fn type_info() -> Type

Returns the static type identifier for Self.

impl<T> EncodeLike for CheckMetadataHash<T>

where PhantomData<T>: Encode,

impl<T: Eq> Eq for CheckMetadataHash<T>

impl<T> StructuralPartialEq for CheckMetadataHash<T>