transport: reject malformed method paths before tap

[sainiranjannallam]

This rejects malformed HTTP/2 method paths in the server transport before invoking InTapHandle. The server already returns Unimplemented for malformed method names before application handlers; validating at transport time keeps tap hooks from observing non-canonical method strings.

The malformed-method regression test now installs an InTapHandle and asserts invalid method paths are rejected without invoking it.

Tests:

• go test ./test -run Test/MalformedMethodPath -count=1
• go test ./test -run 'Test/(MalformedMethodPath|Tap)$' -count=1
• go test ./internal/transport -run 'Test/(HeadersHTTPStatusGRPCStatus|HeadersCausingStreamError)' -count=1

RELEASE NOTES:

• transport: Reject malformed method names before invoking tap handlers.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: sainiranjannallam / name: Sai Niranjan Nallam (6456c4d)

[sainiranjannallam]

Ready for review. EasyCLA is passing now; the only completed failing check is PR validation waiting on a Type: label.

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.06%. Comparing base (b58f32d) to head (f9f665d).
⚠️ Report is 19 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/transport/http2_server.go	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9150      +/-   ##
==========================================
- Coverage   83.18%   83.06%   -0.12%     
==========================================
  Files         418      418              
  Lines       33709    33716       +7     
==========================================
- Hits        28041    28007      -34     
- Misses       4248     4276      +28     
- Partials     1420     1433      +13     

Files with missing lines	Coverage Δ
internal/transport/http2_server.go	90.35% <71.42%> (-0.16%)	⬇️

... and 30 files with indirect coverage changes

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[easwars]

What is the reasoning behind this PR? Why should the tap handlers not see these malformed paths?

[easwars]

FYI, I'm discussing with other gRPC maintainers on what the ideal approach would be to handle this.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.