Closes #2160 First part of [Extrinsic Horizon](https://github.com/paritytech/polkadot-sdk/issues/2415) Introduces a new trait `TransactionExtension` to replace `SignedExtension`. Introduce the idea of transactions which obey the runtime's extensions and have according Extension data (né Extra data) yet do not have hard-coded signatures. Deprecate the terminology of "Unsigned" when used for transactions/extrinsics owing to there now being "proper" unsigned transactions which obey the extension framework and "old-style" unsigned which do not. Instead we have __*General*__ for the former and __*Bare*__ for the latter. (Ultimately, the latter will be phased out as a type of transaction, and Bare will only be used for Inherents.) Types of extrinsic are now therefore: - Bare (no hardcoded signature, no Extra data; used to be known as "Unsigned") - Bare transactions (deprecated): Gossiped, validated with `ValidateUnsigned` (deprecated) and the `_bare_compat` bits of `TransactionExtension` (deprecated). - Inherents: Not gossiped, validated with `ProvideInherent`. - Extended (Extra data): Gossiped, validated via `TransactionExtension`. - Signed transactions (with a hardcoded signature). - General transactions (without a hardcoded signature). `TransactionExtension` differs from `SignedExtension` because: - A signature on the underlying transaction may validly not be present. - It may alter the origin during validation. - `pre_dispatch` is renamed to `prepare` and need not contain the checks present in `validate`. - `validate` and `prepare` is passed an `Origin` rather than a `AccountId`. - `validate` may pass arbitrary information into `prepare` via a new user-specifiable type `Val`. - `AdditionalSigned`/`additional_signed` is renamed to `Implicit`/`implicit`. It is encoded *for the entire transaction* and passed in to each extension as a new argument to `validate`. This facilitates the ability of extensions to acts as underlying crypto. There is a new `DispatchTransaction` trait which contains only default function impls and is impl'ed for any `TransactionExtension` impler. It provides several utility functions which reduce some of the tedium from using `TransactionExtension` (indeed, none of its regular functions should now need to be called directly). Three transaction version discriminator ("versions") are now permissible: - 0b000000100: Bare (used to be called "Unsigned"): contains Signature or Extra (extension data). After bare transactions are no longer supported, this will strictly identify an Inherents only. - 0b100000100: Old-school "Signed" Transaction: contains Signature and Extra (extension data). - 0b010000100: New-school "General" Transaction: contains Extra (extension data), but no Signature. For the New-school General Transaction, it becomes trivial for authors to publish extensions to the mechanism for authorizing an Origin, e.g. through new kinds of key-signing schemes, ZK proofs, pallet state, mutations over pre-authenticated origins or any combination of the above. ## Code Migration ### NOW: Getting it to build Wrap your `SignedExtension`s in `AsTransactionExtension`. This should be accompanied by renaming your aggregate type in line with the new terminology. E.g. Before: ```rust /// The SignedExtension to the basic transaction logic. pub type SignedExtra = ( /* snip */ MySpecialSignedExtension, ); /// Unchecked extrinsic type as expected by this runtime. pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, SignedExtra>; ``` After: ```rust /// The extension to the basic transaction logic. pub type TxExtension = ( /* snip */ AsTransactionExtension<MySpecialSignedExtension>, ); /// Unchecked extrinsic type as expected by this runtime. pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, RuntimeCall, Signature, TxExtension>; ``` You'll also need to alter any transaction building logic to add a `.into()` to make the conversion happen. E.g. Before: ```rust fn construct_extrinsic( /* snip */ ) -> UncheckedExtrinsic { let extra: SignedExtra = ( /* snip */ MySpecialSignedExtension::new(/* snip */), ); let payload = SignedPayload::new(call.clone(), extra.clone()).unwrap(); let signature = payload.using_encoded(|e| sender.sign(e)); UncheckedExtrinsic::new_signed( /* snip */ Signature::Sr25519(signature), extra, ) } ``` After: ```rust fn construct_extrinsic( /* snip */ ) -> UncheckedExtrinsic { let tx_ext: TxExtension = ( /* snip */ MySpecialSignedExtension::new(/* snip */).into(), ); let payload = SignedPayload::new(call.clone(), tx_ext.clone()).unwrap(); let signature = payload.using_encoded(|e| sender.sign(e)); UncheckedExtrinsic::new_signed( /* snip */ Signature::Sr25519(signature), tx_ext, ) } ``` ### SOON: Migrating to `TransactionExtension` Most `SignedExtension`s can be trivially converted to become a `TransactionExtension`. There are a few things to know. - Instead of a single trait like `SignedExtension`, you should now implement two traits individually: `TransactionExtensionBase` and `TransactionExtension`. - Weights are now a thing and must be provided via the new function `fn weight`. #### `TransactionExtensionBase` This trait takes care of anything which is not dependent on types specific to your runtime, most notably `Call`. - `AdditionalSigned`/`additional_signed` is renamed to `Implicit`/`implicit`. - Weight must be returned by implementing the `weight` function. If your extension is associated with a pallet, you'll probably want to do this via the pallet's existing benchmarking infrastructure. #### `TransactionExtension` Generally: - `pre_dispatch` is now `prepare` and you *should not reexecute the `validate` functionality in there*! - You don't get an account ID any more; you get an origin instead. If you need to presume an account ID, then you can use the trait function `AsSystemOriginSigner::as_system_origin_signer`. - You get an additional ticket, similar to `Pre`, called `Val`. This defines data which is passed from `validate` into `prepare`. This is important since you should not be duplicating logic from `validate` to `prepare`, you need a way of passing your working from the former into the latter. This is it. - This trait takes two type parameters: `Call` and `Context`. `Call` is the runtime call type which used to be an associated type; you can just move it to become a type parameter for your trait impl. `Context` is not currently used and you can safely implement over it as an unbounded type. - There's no `AccountId` associated type any more. Just remove it. Regarding `validate`: - You get three new parameters in `validate`; all can be ignored when migrating from `SignedExtension`. - `validate` returns a tuple on success; the second item in the tuple is the new ticket type `Self::Val` which gets passed in to `prepare`. If you use any information extracted during `validate` (off-chain and on-chain, non-mutating) in `prepare` (on-chain, mutating) then you can pass it through with this. For the tuple's last item, just return the `origin` argument. Regarding `prepare`: - This is renamed from `pre_dispatch`, but there is one change: - FUNCTIONALITY TO VALIDATE THE TRANSACTION NEED NOT BE DUPLICATED FROM `validate`!! - (This is different to `SignedExtension` which was required to run the same checks in `pre_dispatch` as in `validate`.) Regarding `post_dispatch`: - Since there are no unsigned transactions handled by `TransactionExtension`, `Pre` is always defined, so the first parameter is `Self::Pre` rather than `Option<Self::Pre>`. If you make use of `SignedExtension::validate_unsigned` or `SignedExtension::pre_dispatch_unsigned`, then: - Just use the regular versions of these functions instead. - Have your logic execute in the case that the `origin` is `None`. - Ensure your transaction creation logic creates a General Transaction rather than a Bare Transaction; this means having to include all `TransactionExtension`s' data. - `ValidateUnsigned` can still be used (for now) if you need to be able to construct transactions which contain none of the extension data, however these will be phased out in stage 2 of the Transactions Horizon, so you should consider moving to an extension-centric design. ## TODO - [x] Introduce `CheckSignature` impl of `TransactionExtension` to ensure it's possible to have crypto be done wholly in a `TransactionExtension`. - [x] Deprecate `SignedExtension` and move all uses in codebase to `TransactionExtension`. - [x] `ChargeTransactionPayment` - [x] `DummyExtension` - [x] `ChargeAssetTxPayment` (asset-tx-payment) - [x] `ChargeAssetTxPayment` (asset-conversion-tx-payment) - [x] `CheckWeight` - [x] `CheckTxVersion` - [x] `CheckSpecVersion` - [x] `CheckNonce` - [x] `CheckNonZeroSender` - [x] `CheckMortality` - [x] `CheckGenesis` - [x] `CheckOnlySudoAccount` - [x] `WatchDummy` - [x] `PrevalidateAttests` - [x] `GenericSignedExtension` - [x] `SignedExtension` (chain-polkadot-bulletin) - [x] `RefundSignedExtensionAdapter` - [x] Implement `fn weight` across the board. - [ ] Go through all pre-existing extensions which assume an account signer and explicitly handle the possibility of another kind of origin. - [x] `CheckNonce` should probably succeed in the case of a non-account origin. - [x] `CheckNonZeroSender` should succeed in the case of a non-account origin. - [x] `ChargeTransactionPayment` and family should fail in the case of a non-account origin. - [ ] - [x] Fix any broken tests. --------- Signed-off-by: georgepisaltu <george.pisaltu@parity.io> 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Basic Example Pallet
The Example: A simple example of a FRAME pallet demonstrating concepts, APIs and structures common to most FRAME runtimes.
Run cargo doc --package pallet-example-basic --open to view this pallet's documentation.
This pallet serves as an example and is not meant to be used in production.
Documentation Guidelines
- Documentation comments (i.e.
/// comment) - should accompany pallet functions and be restricted to the pallet interface, not the internals of the pallet implementation. Only state inputs, outputs, and a brief description that mentions whether calling it requires root, but without repeating the source code details. Capitalize the first word of each documentation comment and end it with a full stop. See Generic example of annotating source code with documentation comments - Self-documenting code - Try to refactor code to be self-documenting.
- Code comments - Supplement complex code with a brief explanation, not every line of code.
- Identifiers - surround by backticks (i.e.
INHERENT_IDENTIFIER,InherentType,u64) - Usage scenarios - should be simple doctests. The compiler should ensure they stay valid.
- Extended tutorials - should be moved to external files and refer to.
- Mandatory - include all of the sections/subsections where MUST is specified.
- Optional - optionally include sections/subsections where CAN is specified.
Documentation Template:
Copy and paste this template from frame/examples/basic/src/lib.rs into file
frame/<INSERT_CUSTOM_PALLET_NAME>/src/lib.rs of your own custom pallet and complete it.
// Add heading with custom pallet name# <INSERT_CUSTOM_PALLET_NAME> Pallet
// Add simple description
// Include the following links that shows what trait needs to be implemented to use the pallet // and the supported dispatchables that are documented in the Call enum.
- [
<INSERT_CUSTOM_PALLET_NAME>::Config](https://docs.rs/pallet-example-basic/latest/pallet_example_basic/trait.Config.html) - [
Call](https://docs.rs/pallet-example-basic/latest/pallet_example_basic/enum.Call.html) - [
Module](https://docs.rs/pallet-example-basic/latest/pallet_example_basic/struct.Module.html)
## Overview
// Short description of pallet's purpose. // Links to Traits that should be implemented. // What this pallet is for. // What functionality the pallet provides. // When to use the pallet (use case examples). // How it is used. // Inputs it uses and the source of each input. // Outputs it produces.
## Terminology
// Add terminology used in the custom pallet. Include concepts, storage items, or actions that you think // deserve to be noted to give context to the rest of the documentation or pallet usage. The author needs to // use some judgment about what is included. We don't want a list of every storage item nor types - the user // can go to the code for that. For example, "transfer fee" is obvious and should not be included, but // "free balance" and "reserved balance" should be noted to give context to the pallet. // Please do not link to outside resources. The reference docs should be the ultimate source of truth.
## Goals
// Add goals that the custom pallet is designed to achieve.
### Scenarios
#### <INSERT_SCENARIO_NAME>
// Describe requirements prior to interacting with the custom pallet. // Describe the process of interacting with the custom pallet for this scenario and public API functions used.
## Interface
### Supported Origins
// What origins are used and supported in this pallet (root, signed, none)
// i.e. root when `ensure_root` used
// i.e. none when `ensure_none` used
// i.e. signed when `ensure_signed` used
`inherent` <INSERT_DESCRIPTION>
### Types
// Type aliases. Include any associated types and where the user would typically define them.
`ExampleType` <INSERT_DESCRIPTION>
// Reference documentation of aspects such as storageItems and dispatchable functions should only be
// included in the https://docs.rs Rustdocs for Substrate and not repeated in the README file.
### Dispatchable Functions
// A brief description of dispatchable functions and a link to the rustdoc with their actual documentation.
// MUST have link to Call enum // MUST have origin information included in function doc // CAN have more info up to the user
### Public Functions
// A link to the rustdoc and any notes about usage in the pallet, not for specific functions. // For example, in the Balances Pallet: "Note that when using the publicly exposed functions, // you (the runtime developer) are responsible for implementing any necessary checks // (e.g. that the sender is the signer) before calling a function that will affect storage."
// It is up to the writer of the respective pallet (with respect to how much information to provide).
#### Public Inspection functions - Immutable (getters)
// Insert a subheading for each getter function signature
##### `example_getter_name()`
// What it returns // Why, when, and how often to call it // When it could panic or error // When safety issues to consider
#### Public Mutable functions (changing state)
// Insert a subheading for each setter function signature
##### `example_setter_name(origin, parameter_name: T::ExampleType)`
// What state it changes // Why, when, and how often to call it // When it could panic or error // When safety issues to consider // What parameter values are valid and why
### Storage Items
// Explain any storage items included in this pallet
### Digest Items
// Explain any digest items included in this pallet
### Inherent Data
// Explain what inherent data (if any) is defined in the pallet and any other related types
### Events:
// Insert events for this pallet if any
### Errors:
// Explain what generates errors
## Usage
// Insert 2-3 examples of usage and code snippets that show how to // use <INSERT_CUSTOM_PALLET_NAME> Pallet in a custom pallet.
### Prerequisites
// Show how to include necessary imports for <INSERT_CUSTOM_PALLET_NAME> and derive
// your pallet configuration trait with the INSERT_CUSTOM_PALLET_NAME trait.
```rust use <INSERT_CUSTOM_PALLET_NAME>;
pub trait Config: <INSERT_CUSTOM_PALLET_NAME>::Config { } ```
### Simple Code Snippet
// Show a simple example (e.g. how to query a public getter function of <INSERT_CUSTOM_PALLET_NAME>)
### Example from FRAME
// Show a usage example in an actual runtime
// See: // - Substrate TCR https://github.com/parity-samples/substrate-tcr // - Substrate Kitties https://shawntabrizi.github.io/substrate-collectables-workshop/#/
## Genesis Config
## Dependencies
// Dependencies on other FRAME pallets and the genesis config should be mentioned, // but not the Rust Standard Library. // Genesis configuration modifications that may be made to incorporate this pallet // Interaction with other pallets
## Related Pallets
// Interaction with other pallets in the form of a bullet point list
## References
// Links to reference material, if applicable. For example, Phragmen, W3F research, etc. // that the implementation is based on.
License: MIT-0