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[Identity] Add authenticated gRPC service
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Authored by jon on Jul 6 2023, 2:09 PM.
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Details

Summary

Add another grpc service for authenticated requests.
This differs from the existing service by having an interceptor
which will fail if authentication did not succeed.

Test Plan

N/A. Implementation in later diff.
This is meant to be more of a design review.

Diff Detail

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Harbormaster returned this revision to the author for changes because remote builds failed.Jul 6 2023, 2:23 PM
Harbormaster failed remote builds in B20780: Diff 28459!

so basically just passing the token, user id, and device id as metadata instead of message fields?

bartek added 1 blocking reviewer(s): varun.
In D8434#249580, @varun wrote:

so basically just passing the token, user id, and device id as metadata instead of message fields?

Yeah looks so and I really like this idea

varun requested changes to this revision.Jul 11 2023, 11:17 AM

rather than creating a new .proto file, can we just add the interceptor to the existing .proto?

services/identity/src/grpc_services/authenticated.rs
4 ↗(On Diff #28554)

i'm not sure i understand this comment. why do we need the client module here at all?

50 ↗(On Diff #28554)

also not sure i understand this comment. do you mean it must be run synchronously?

73 ↗(On Diff #28554)

seems weird to return Empty from the client module instead of something from the auth_proto module

This revision now requires changes to proceed.Jul 11 2023, 11:17 AM
jon added inline comments.
services/identity/src/grpc_services/authenticated.rs
4 ↗(On Diff #28554)

Because when importing from other proto files, tonic will reflect the structure of imported structs based on their protobuf package paths. In this case we need Empty and PreKey from the identity.client protobuf package, and tonic will refer to this as client::Empty and client::PreKey in rust.

Would like like to reword the comment?

// This must be named client, because generated code from the authenticated protobuf file
// references message structs from the client protobuf file with the client:: namespace

I decided to just change the comment, as the current comment doesn't seem to be satisfactory.

50 ↗(On Diff #28554)

auth_intercept can't be async (otherwise the types don't match). So new_db_client.verify_access_token which is async can't be awaited normally. Instead I have to do this work around which involves tokio pinning the action on the current thread.

Handle::block_on is the only way I'm aware to get around an explicit .await.

50 ↗(On Diff #28554)

I reworded the comment to be more clear.

73 ↗(On Diff #28554)

I don't think so, there' will be others around key management that should be shared as well in the future.

Eventually I would like to see:

  • identity.proto -> shared messages used between both the unauthenticated and authenticated services (Empty, PreKey, IdentityKeyInfo)
  • identity_client.proto RPCs and structs specific for unauthenticated clients
  • identity_authenticated.proto RPCs and structs specific for authenticated clients.

Also reduce the size of the individual proto files. identity_client is already ~360 lines long.

jon marked 3 inline comments as done.

Address feedback

varun requested changes to this revision.EditedJul 13 2023, 11:54 AM

i don't love that we block on verify_access_token in the interceptor function. would rather use a tower layer instead of a tonic interceptor to call the code asynchronously, or just call an authenticate helper function at the start of each service method

This revision now requires changes to proceed.Jul 13 2023, 11:54 AM

i don't love that we block on verify_access_token in the interceptor function. would rather use a tower layer instead of a tonic interceptor to call the code asynchronously,

We need to verify the access token, I don't see how we can get around blocking the request until we made the determination for passing the request through.

Also, looking at the tower example code, I'm not sure if it's a strict improvement anymore, looks like there still a few oddities to get the middleware to play nicely: https://github.com/hyperium/tonic/blob/master/examples/src/tower/server.rs

or just call an authenticate helper function at the start of each service method

From the perspective of the calling client, this would still be the same amount of time. Real difference is whether you want the handler to be aware of it.

I think the issue of awaiting for DDB can be mitigated by using some type of LRU cache. I'm assuming in the future that authenticating devices are likely going to burst with requests (e.g. fan-out of X3DH messages).

This revision is now accepted and ready to land.Jul 20 2023, 10:01 AM
This revision was automatically updated to reflect the committed changes.