h3-proxy: fix callback return values, and a typo in tests

[vszakats]

• replace literal -1 with NGHTTP3_ERR_CALLBACK_FAILURE in nghttp3
  callback.
• replace NGHTTP3_ERR_CALLBACK_FAILURE with
  NGTCP2_ERR_CALLBACK_FAILURE in ngtcp2 callbacks.
• test_60_h3_proxy: fix non-critical typo in symbol.

Spotted by GitHub Code Quality

Follow-up to e78b1b3 #21153

[Copilot]

Pull request overview

This PR corrects error codes returned from nghttp3/ngtcp2 callbacks in the HTTP/3 proxy filter and fixes a small typo in an HTTP/3 proxy test, aligning behavior with the respective libraries’ expected callback-failure return values.

Changes:

• Replace a literal -1 with NGHTTP3_ERR_CALLBACK_FAILURE in an nghttp3 callback.
• Replace incorrect NGHTTP3_ERR_CALLBACK_FAILURE returns with NGTCP2_ERR_CALLBACK_FAILURE in ngtcp2 callbacks.
• Fix a typo in the test helper invocation (nghttps_fwd → nghttpx_fwd).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
lib/cf-h3-proxy.c	Uses the correct nghttp3/ngtcp2 callback failure constants for error returns.
tests/http/test_60_h3_proxy.py	Fixes a typo in _require_available(...) kwargs to reference nghttpx_fwd correctly.

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[testclutch]

Analysis of PR #21802 at c10adfba:

Test ../../tests/http/test_60_h3_proxy.py::TestH3ProxyFailure::test_60_02_connect_tunnel_fail[fail_h2_over_h3_proxytunnel] failed, which has NOT been flaky recently, so there could be a real issue in this PR. Note that this test has failed in 2 different CI jobs (the link just goes to one of them).

Test ../../tests/http/test_60_h3_proxy.py::TestH3ProxyFailure::test_60_02_connect_tunnel_fail[fail_h3_over_h2_proxytunnel] failed, but it has been permanently failing lately, so it's probably NOT a fault of the PR. Note that this test has failed in 4 different CI jobs (the link just goes to one of them).

Test ../../tests/http/test_60_h3_proxy.py::TestH3ProxyModeSelection::test_60_03_h3_target_auto_connect_udp[proxy_h3] failed, but it has been permanently failing lately, so it's probably NOT a fault of the PR. Note that this test has failed in 4 different CI jobs (the link just goes to one of them).

Generated by Testclutch