Support logging non-URLSession traffic (gRPC) and streamed request bodies

[ffittschen]

This issue proposes a few additions so Pulse can show traffic that doesn't go through URLSession, starting with grpc-swift-2 clients, and so it captures request bodies that URLSession streams. I opened the PRs below as drafts so we can agree on the approach here first.

Motivation

• gRPC over SwiftNIO doesn't show up. grpc-swift v2, like other SwiftNIO-based clients (Is there a way to get Pulse working with NIO. #291), never touches URLSession. The only public way to log such a task today is LoggerStore.storeRequest, which stores the task once it has finished and skips NetworkLogger's filters and redaction.
• swift-openapi-urlsession's request bodies are missing. Its default transport streams bodies through the task delegate's needNewBodyStream, so PulseProxy logs those requests without a body.

What I built

PulseGRPC is a small package with a grpc-swift v2 ClientInterceptor. It logs every RPC as a Pulse network task:

• a grpcs://host/package.Service/Method URL and the grpc label
• messages as JSON bodies
• metadata as headers, plus grpc-status
• the duration, sizes and timing, and a failure state.

It lives outside Pulse, so Pulse doesn't need to depend on grpc-swift-2. To fully function, it needs a few changes in Pulse, which I have outlined below.

Proposed changes (draft PRs)

What PulseGRPC needs

• Support logging network tasks that don't use URLSession #382: NetworkLogger.logTaskCreated(taskId:…) and logTaskCompleted(taskId:…), for tasks without a URLSessionTask. They're stateless and keyed by a task ID the caller provides. They go through send(_:), so filters, redaction and willHandleEvent apply. A second commit shows the descriptions of custom-domain errors instead of "Error" in the console, partway towards Improved NSURLError/custom network error support #341.

What swift-openapi-urlsession needs

• Capture upload request bodies in PulseProxy #383: capture the request bodies of uploads from data (uploadTask(with:from:), upload(for:from:)) and of streamed uploads (needNewBodyStream), which covers swift-openapi-urlsession. Builds on Fix URLSessionProxy async uploads ignoring the task delegate #381.

Fixes found along the way (each one stands on its own)

• Fix case-insensitive matching of sensitive headers #379: sensitiveHeaders matched case-sensitively, so a lowercase authorization didn't redact Authorization.
• Fix upload task response body size #380: upload tasks kept responseBodySize = -1.
• Fix URLSessionProxy async uploads ignoring the task delegate #381: URLSessionProxy's async uploads ignored the task delegate and stayed pending.

Not opened as PRs, but I have them ready if you want them:

• Docs for closeButtonHidden(_:) on consoles pushed onto a navigation stack. ConsoleView shows its close button whenever presentationMode.isPresented is true, and that's also true for pushed views, so they show a close button next to the back button.
• .scripts/build.sh ignores -s and build failures, so the iOS and tvOS CI jobs currently build nothing.

A possible follow-up I haven't written yet: contentType looks up headers["Content-Type"] case-sensitively, so a task logged through the new methods with HTTP/2-style lowercase content-type loses its content type, and PulseGRPC has to keep that one header capitalized.

None of the PRs touch CHANGELOG.md. Please let me know if I should add the entries or if you prefer to do that.

Design choices

Bodies are JSON

PulseGRPC stores protobuf messages as JSON with Content-Type: application/json. The viewer, search, sensitiveDataFields, export and Pulse Pro then work unchanged, and the protobuf content-type hooks keep their meaning.

No schema or protocol changes

Tasks are .dataTasks with a grpc:// or grpcs:// URL, a grpc label and a grpc-status header. TaskType, the Core Data model and the remote-logging protocol are untouched, so .pulse files, Pulse for Mac and Pulse Pro keep working.

A stateless API

An alternative is a handle-based API on top: startTask(...) -> TaskHandle with finish(...), a lock, and a deinit that logs an abandoned task as cancelled. It's harder to misuse, but it adds a public type with lifecycle rules. I'm happy to switch if you prefer that.

Streamed bodies use swizzling

In the style PulseProxy already uses: hooks on the app's delegate classes, once per class, and a tee on one shared thread. #383 lists the limitations.

Questions

1. Would you accept the two NetworkLogger methods, and are you happy with the names?
2. Should PulseGRPC stay a separate package that the README links to? Or would you rather have it in this repo as its own product, which would add grpc-swift-2 to Package.swift?
3. Is the amount of swizzling in Capture upload request bodies in PulseProxy #383 acceptable, or would you rather leave streamed bodies out?