Add method for getting permitted plugins

[rekmarks]

There's no dedicated way for domains to check if a plugin is installed and permitted. We should add an external wallet_ RPC method to check whether a plugin is installed, and potentially get metadata about e.g. the version and so on.

This suggestion did not originally contain the "permitted" condition. We should not let external domains poll for plugins without having permissions to them.

This method will either be an entirely new wallet_getPlugins RPC method or a modification of the soon-to-be-implemented wallet_installPlugins method.

[danfinlay]

This could be a privacy leak. When is it valuable to detect a plugin without just asking permission to interact with it?

[rekmarks]

This suggestion originally came from @oed. The goal is for consumers of our API to have a means of checking whether a plugin is installed without initiating the installation or permission request flow. This would enable better UX, e.g. by not displaying the Connect button if the plugin is already installed.

Always reinstalling the plugin when the permission for it is requested is (as discussed internally) a stopgap measure. However, using wallet_requestPermissions to check if a plugin is installed would still re-request the permission for the plugin. Whether we'll change that behavior in the necessary timeframe or at all is an open question.

Furthermore, in the future we'll want to let API consumers know what version of a plugin is installed, and we'll need something like wallet_getPluginManifest to accomplish that. Alternatively, we could add that information to the plugin permission itself, but that seems like poor separation of concerns.

Finally, this would not cause any privacy leaks because we already allow API consumers to call wallet_getPermissions.

[oed]

@danfinlay Right now when you ask for permission the install plugin is always displayed. If in the future that is only displayed if you have not yet been granted permission I think that would be fine as well. At least for my use case.

[danfinlay]

Right now when you ask for permission the install plugin is always displayed. If in the future that is only displayed if you have not yet been granted permission I think that would be fine as well. At least for my use case.

Yes I agree this is fine. We could already easily do a check: If the plugin is installed, only ask the user to connect to it. Right now we always re-install really just as a developer convenience feature, but we should probably replace it as soon as we have a reasonable plugin-update mechanism (maybe the mm-plugin serve API could host a websocket that notifies it to reload for now).

Furthermore, in the future we'll want to let API consumers know what version of a plugin is installed

I'm not certain how we'll address this, but it may be more like a dependency graph: Let dapps/plugins specify the versions they want. Maybe updates are always hosted at new addresses, or maybe we define a special wallet-plugin ENS content type that includes a map of versions, so that a plugin origin can specify a variety of versions that can be referenced.

[oed]

Yes I agree this is fine. We could already easily do a check: If the plugin is installed, only ask the user to connect to it.

This is fine if: The user is only asked the first time they use app A that uses plugin B. The second time the user comes to app A they should not have to reaffirm that app A can use plugin B (it's fine if there is some timeout here).

[awalias]

what is currently the best way to check whether a user has previously granted a given permission for the current domain?

[rekmarks]

@awalias I'll make sure this is added to the Wiki where appropriate but for now:

• We follow the spec we've made for permissions: EIP 2255

• To know whether you have a certain permission, send a wallet_getPermissions request and search over the returned array of permissions objects.

  • The permission name is indicated by the parentCapability field.
  • You can also attempt to call the corresponding method. If you don't have the permission, an EIP 1193 Unauthorized error will be returned, with error.code === 4100.
  • These methods will not tell you if you've previously granted the permission and it's later been removed.

• If you need to know if you've previously granted the permission at all - even if it's been removed - you have to keep track of that information.

Does this answer your question?

Edit: updated wiki: https://github.com/MetaMask/metamask-snaps-beta/wiki/Plugin-and-Dapp-Permissions

[awalias]

thanks @rekmarks , I eventually got wallet_getPermissions to work - my problem was that simply having import Web3 from 'web3'; (web3@1.2.4) in react was causing the ethereum.send with wallet_getPermissions to return undefined. I'm assuming it does something to the provider, but definitely not playing nice together atm. I switched to ethers.js for now and seems to be working ok.

[rekmarks]

This issue has been updated to say that plugins must be "installed and permitted" in order to be returned by the yet-to-be-implemented wallet_getPlugins method.

There's also a world where we modify the soon-to-be-implemented wallet_installPlugins to include a force: boolean parameter which will attempt to force plugin reinstallation. If that parameter is false and the plugin is already installed, that can just return data about the plugin. wallet_getPlugins seems nice to have for completeness, though.