# Permission System 2.0
## Background
This PR migrates the extension permission system to [the new `PermissionController`](https://github.com/MetaMask/snaps-skunkworks/tree/main/packages/controllers/src/permissions).
The original permission system, based on [`rpc-cap`](https://github.com/MetaMask/rpc-cap), introduced [`ZCAP-LD`](https://w3c-ccg.github.io/zcap-ld/)-like permissions to our JSON-RPC stack.
We used it to [implement](https://github.com/MetaMask/metamask-extension/pull/7004) what we called "LoginPerSite" in [version 7.7.0](https://github.com/MetaMask/metamask-extension/releases/tag/v7.7.0) of the extension, which enabled the user to choose which accounts, if any, should be exposed to each dapp.
While that was a worthwhile feature in and of itself, we wanted a permission _system_ in order to enable everything we are going to with Snaps.
Unfortunately, the original permission system was difficult to use, and necessitated the creation of the original `PermissionsController` (note the "s"), which was more or less a wrapper for `rpc-cap`.
With this PR, we shake off the yoke of the original permission system, in favor of the modular, self-contained, ergonomic, and more mature permission system 2.0.
Note that [the `PermissionController` readme](https://github.com/MetaMask/snaps-skunkworks/tree/main/packages/controllers/src/permissions/README.md) explains how the new permission system works.
The `PermissionController` and `SubjectMetadataController` are currently shipped via `@metamask/snap-controllers`. This is a temporary state of affairs, and we'll move them to `@metamask/controllers` once they've landed in prod.
## Changes in Detail
First, the changes in this PR are not as big as they seem. Roughly half of the additions in this PR are fixtures in the test for the new migration (number 68), and a significant portion of the remaining ~2500 lines are due to find-and-replace changes in other test fixtures and UI files.
- The extension `PermissionsController` has been deleted, and completely replaced with the new `PermissionController` from [`@metamask/snap-controllers`](https://www.npmjs.com/package/@metamask/snap-controllers).
- The original `PermissionsController` "domain metadata" functionality is now managed by the new `SubjectMetadataController`, also from [`@metamask/snap-controllers`](https://www.npmjs.com/package/@metamask/snap-controllers).
- The permission activity and history log controller has been renamed `PermissionLogController` and has its own top-level state key, but is otherwise functionally equivalent to the existing implementation.
- Migration number 68 has been added to account for the new state changes.
- The tests in `app/scripts/controllers/permissions` have been migrated from `mocha` to `jest`.
Reviewers should focus their attention on the following files:
- `app/scripts/`
- `metamask-controller.js`
- This is where most of the integration work for the new `PermissionController` occurs.
Some functions that were internal to the original controller were moved here.
- `controllers/permissions/`
- `selectors.js`
- These selectors are for `ControllerMessenger` selector subscriptions. The actual subscriptions occur in `metamask-controller.js`. See the `ControllerMessenger` implementation for details.
- `specifications.js`
- The caveat and permission specifications are required by the new `PermissionController`, and are used to specify the `eth_accounts` permission and its JSON-RPC method implementation.
See the `PermissionController` readme for details.
- `migrations/068.js`
- The new state should be cross-referenced with the controllers that manage it.
The accompanying tests should also be thoroughly reviewed.
Some files may appear new but have just moved and/or been renamed:
- `app/scripts/lib/rpc-method-middleware/handlers/request-accounts.js`
- This was previously implemented in `controllers/permissions/permissionsMethodMiddleware.js`.
- `test/mocks/permissions.js`
- A truncated version of `test/mocks/permission-controller.js`.
Co-authored-by: Mark Stacey <markjstacey@gmail.com>
* Specify type before parameter name
Various JSDoc `@param` entries were specified as `name {type}` rather
than `{type} name`.
A couple of `@return` entries have been given types as well.
* Use JSDoc optional syntax rather than Closure syntax
* Use @returns rather than @return
* Use consistent built-in type capitalization
Primitive types are lower-case, and Object is upper-case.
* Separate param/return description with a dash
Fixed warnings:
```md
app/scripts/controllers/computed-balances.js
+ 35:27 warning Missing space before function parentheses space-before-function-paren
+ 41:14 warning 'address' is never reassigned. Use 'const' instead prefer-const
+ 61:9 warning 'updater' is never reassigned. Use 'const' instead prefer-const
+ 68:11 warning 'newState' is never reassigned. Use 'const' instead prefer-const
app/scripts/controllers/network.js
+ 104:29 warning Missing space before function parentheses space-before-function-paren
app/scripts/lib/createLoggerMiddleware.js
+ 4:32 warning Missing space before function parentheses space-before-function-paren
+ 15:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/createOriginMiddleware.js
+ 4:32 warning Missing space before function parentheses space-before-function-paren
+ 9:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/createProviderMiddleware.js
+ 5:34 warning Missing space before function parentheses space-before-function-paren
+ 13:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/events-proxy.js
+ 1:50 warning Missing space before function parentheses space-before-function-paren
+ 31:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/nodeify.js
+ 2:22 warning Missing space before function parentheses space-before-function-paren
+ 2:24 warning Missing space before opening brace space-before-blocks
+ 5:18 warning Missing space before function parentheses space-before-function-paren
+ 5:20 warning Missing space before opening brace space-before-blocks
app/scripts/lib/pending-balance-calculator.js
+ 16:19 warning Missing space before function parentheses space-before-function-paren
app/scripts/lib/pending-tx-tracker.js
+ 85:11 warning '||' should be placed at the end of the line operator-linebreak
+ 87:11 warning '||' should be placed at the end of the line operator-linebreak
+ 88:11 warning '||' should be placed at the end of the line operator-linebreak
+ 90:11 warning '||' should be placed at the end of the line operator-linebreak
+ 91:11 warning '||' should be placed at the end of the line operator-linebreak
app/scripts/lib/port-stream.js
+ 3:22 warning Missing space before function parentheses space-before-function-paren
+ 3:24 warning Missing space before opening brace space-before-blocks
app/scripts/lib/tx-gas-utils.js
+ 84:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/tx-state-history-helper.js
+ 12:37 warning Missing space before function parentheses space-before-function-paren
+ 23:30 warning Missing space before function parentheses space-before-function-paren
+ 30:23 warning Missing space before function parentheses space-before-function-paren
+ 35:28 warning Missing space before function parentheses space-before-function-paren
+ 41:2 warning Newline required at end of file but not found eol-last
app/scripts/lib/tx-state-manager.js
+ 94:13 warning 'value' is never reassigned. Use 'const' instead prefer-const
ui/app/reducers.js
+ 45:7 warning 'state' is never reassigned. Use 'const' instead prefer-const
+ 53:7 warning 'stateString' is never reassigned. Use 'const' instead prefer-const
ui/lib/tx-helper.js
+ 27:2 warning Newline required at end of file but not found eol-last
ui/app/components/account-dropdowns.js
+ 163:1 warning More than 2 blank lines not allowed no-multiple-empty-lines
ui/app/components/menu-droppo.js
+ 22:7 warning 'style' is never reassigned. Use 'const' instead prefer-const
ui/app/components/shapeshift-form.js
+ 135:11 warning '&&' should be placed at the end of the line operator-linebreak
ui/app/components/typed-message-renderer.js
+ 35:25 warning Missing space before function parentheses space-before-function-paren
+ 42:2 warning Newline required at end of file but not found eol-last
mascara/server/index.js
+ 11:42 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 12:36 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 13:33 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 14:40 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 20:29 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 21:29 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
+ 26:40 warning Use path.join() or path.resolve() instead of + to create paths no-path-concat
```
If a nodified method does not return a Promise, it will throw an error, like this:
```
Error in event handler for (unknown): Error: The function setSelectedAccount did not return a Promise, but was nodeified.
```
Mostly Fixes#893
A couple methods cache callbacks, and will require a larger refactor to fully denodeify.
Specifically, our methods involving web3 requests to sign a tx, sign a message, and approve or cancel either of those.
I think we should postpone those until the TxManager refactor, since it will likely handle this response caching itself.
