[Tx ext stage 2: 1/4] Add TransactionSource as argument in TransactionExtension::validate

[gui1117]

Meta

This PR is part of 4 PR:

• [Tx ext stage 2: 1/4] Add TransactionSource as argument in TransactionExtension::validate #6323
• [Tx ext stage 2: 2/4] Introduce #[pallet::authorize(...)] macro attribute and AuthorizeCall system transaction extension #6324
• [Tx ext stage 2: 3/4] use #[pallet::authorize(...)] to migrate unsigned in system: tasks + apply_authorized_call #6325
• [Tx ext stage 2: 4/4] use #[pallet::authorize(...)] to migrate all unsigned in polkadot-sdk #6326

Description

One goal of transaction extension is to get rid or unsigned transactions.
But unsigned transaction validation has access to the TransactionSource.

The source is used for unsigned transactions that the node trust and don't want to pay upfront.
Instead of using transaction source we could do: the transaction is valid if it is signed by the block author, conceptually it should work, but it doesn't look so easy.

This PR add TransactionSource to the validate function for transaction extensions

[lexnv]

outside of this PR: I think we'll also need:

/// Versions for which this Transaction Extension is applicable.
const VERSIONS: &'static [u8]

I could handle this in my metadata update PR

[georgepisaltu]

I don't think we'll do it that way but rather a list of versions supported in the current TxExtension definition, which would end up being an enum like structure for each supported version. But in this format, it would not be on the TransactionExtension trait definition, but on the ExtrinsicMetadata definition, as in one for the big, tuple extension of the runtime.

[bkchr]

@lexnv what you mean by this?

[lexnv]

I've created a new PR for frame-metadata to add a few minor changes. The ExtrinsicMetadata looks like:

pub struct ExtrinsicMetadata<T: Form = MetaForm> {
	/// Extrinsic versions.
	pub versions: Vec<u8>,
	/// The type of the address that signs the extrinsic
	pub address_ty: T::Type,
	/// The type of the extrinsic's signature.
	pub signature_ty: T::Type,
	/// A mapping of supported transaction extrinsic versions to their respective transaction extension indexes.
	///
	/// For each supported version number, list the indexes, in order, of the extensions used.
	pub transaction_extensions_by_version: BTreeMap<u8, Vec<u32>>,
	/// The transaction extensions in the order they appear in the extrinsic.
	pub transaction_extensions: Vec<TransactionExtensionMetadata<T>>,
}

• (1) ExtrinsicMetadata::versions should be [4 (legacy), 5 (new format)]. This can be done by changing the ExtrinsicMetadata trait

• (2) TransactionExtensionMetadata are grouped by their extension version (currently only version 0u8 is supported). But in the future we might have multiple transaction extension versions which have different tx extensions and possibly different order of encoding

I wanted to get the information from (2) available for collection in metadata 🤔 Just to double check is my understanding of (2) correct? 🙏

[gui1117]

I think (1) is correct to me.

in (2) you mean that a transaction extension like CheckWeight will be valid for a predefined set of version? This is not the correct level. The runtime is defining multiple version of transaction extension set.

So a runtime can have:

• Transaction extensions version 33: CheckWeight + Payment.
• Transaction extensions version 34: CheckWeight + Payment + CheckMetadataVersion.
• Transaction extensions version 35: Payment.

Then an extrinsic can choose one transaction extensions version.

I believe the syntax will be something a bit like: (syntax can be different)

type UncheckedExtrinsic = UncheckedExtrinsic<Address, Signature, ((const 33, TxExtensionV33), (const 34, TxExtensionV34), (const 35, TxExtensionV35))>

type TxExtensionV33 = (CheckWeight, Payment);

//etc...

[bkchr]

Yeah 1 and 2 make sense. However, I still don't get the initial comment. Maybe what Guillaume has written above makes it more clear. The version is in the runtime and not in the extension. If we need to change extensions, we need to give them a new name.

[lexnv]

LGTM!

[paritytech-cmd-bot-polkadot-sdk]

Created backport PR for stable2407:

• [stable2407] Backport #6323 #6471 with remaining conflicts!

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-6323-to-stable2407
git worktree add --checkout .worktree/backport-6323-to-stable2407 backport-6323-to-stable2407
cd .worktree/backport-6323-to-stable2407
git reset --hard HEAD^
git cherry-pick -x 8e3d929623d43398ed3ab8c9ca813aff32588011
git push --force-with-lease

[paritytech-cmd-bot-polkadot-sdk]

Created backport PR for stable2409:

• [stable2409] Backport #6323 #6472 with remaining conflicts!

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-6323-to-stable2409
git worktree add --checkout .worktree/backport-6323-to-stable2409 backport-6323-to-stable2409
cd .worktree/backport-6323-to-stable2409
git reset --hard HEAD^
git cherry-pick -x 8e3d929623d43398ed3ab8c9ca813aff32588011
git push --force-with-lease