http_client_http2: bracket IPv6 authority hosts

[edsiper]

fixes #11895

Fix HTTP/2 :authority generation for IPv6 literal hosts by formatting
unbracketed IPv6 addresses as [host]:port.

Root Cause

The HTTP/2 client built request->authority by appending :<port> directly to
request->host. For IPv6 literals this produced invalid authority values such
as ::1:4317, which strict HTTP/2 servers reject. The older HTTP/1 Host header
path already handled IPv6 bracketing, but the newer HTTP/2 request path did not.

Changes

• Add IPv6 literal detection in src/flb_http_client_http2.c.
• Format HTTP/2 authority as [ipv6]:port for unbracketed IPv6 literals.
• Add an out_opentelemetry integration scenario using IPv6 loopback and HTTP/2.
• Add a focused raw HTTP/2 test receiver that asserts the emitted :authority.

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

Summary by CodeRabbit

• Improvements

  • Better IPv6 address handling and authority header formatting for HTTP/2 requests
  • Improved Windows socket compatibility for the HTTP/2 client

• Tests

  • Added IPv6 HTTP/2 integration tests for OpenTelemetry logging (validates :authority and path)
  • Added test dependency: h2 (pinned to 4.1.0)

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: d72db934-8266-454d-a00e-b11cbdcec6e2

📥 Commits

Reviewing files that changed from the base of the PR and between 4fe85f0 and a7e5c40.

📒 Files selected for processing (4)

• src/flb_http_client_http2.c
• tests/integration/requirements.txt
• tests/integration/scenarios/out_opentelemetry/config/out_otel_http2_ipv6_logs.yaml
• tests/integration/scenarios/out_opentelemetry/tests/test_out_opentelemetry_001.py

✅ Files skipped from review due to trivial changes (1)

• tests/integration/requirements.txt

🚧 Files skipped from review as they are similar to previous changes (2)

• tests/integration/scenarios/out_opentelemetry/config/out_otel_http2_ipv6_logs.yaml
• src/flb_http_client_http2.c

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📝 Walkthrough

Walkthrough

Adds IPv6-literal detection and authority formatting for HTTP/2 requests, replaces inline authority construction in the request commit path with the new helper, and adds an integration test (with h2) that verifies bracketed IPv6 :authority on the IPv6 loopback.

Changes

IPv6 HTTP/2 Authority Header Formatting

Layer / File(s)	Summary
IPv6 authority format helpers in HTTP/2 client src/flb_http_client_http2.c	Adds Windows socket headers and implements http2_is_ipv6_literal() to detect IPv6 literals (supports %zone) and http2_request_set_authority() to allocate/format request->authority as host:port or [host]:port with error handling.
Apply authority helpers in request commit src/flb_http_client_http2.c	Replaces manual request->authority construction in flb_http2_request_commit() with http2_request_set_authority(request), removes the temporary sds_result variable, and adds early failure handling for allocation/format errors.
IPv6 HTTP/2 OTLP integration test tests/integration/requirements.txt, tests/integration/scenarios/out_opentelemetry/config/out_otel_http2_ipv6_logs.yaml, tests/integration/scenarios/out_opentelemetry/tests/test_out_opentelemetry_001.py	Adds h2==4.1.0, a YAML test scenario targeting ::1:<port>, an IPv6-capable HTTP/2 OTLP receiver/service wrapper, and a test that asserts /v1/logs path and :authority equals [::1]:<port>.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested reviewers

• cosmo0920

Poem

🐰 IPv6 brackets, now in place!
Six colons wrapped with grace,
Authority headers, RFC-compliant and bright,
HTTP/2 flows now set it right! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 4.55% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'http_client_http2: bracket IPv6 authority hosts' accurately describes the main change—fixing HTTP/2 authority header generation for IPv6 addresses by adding bracketing.
Linked Issues check	✅ Passed	The PR successfully addresses all requirements from issue #11895: IPv6 literal detection, RFC-compliant bracketed authority formatting, and comprehensive test coverage via IPv6 HTTP/2 integration tests.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to issue #11895: HTTP/2 client IPv6 authority formatting, supporting infrastructure (test requirements, test configuration), and validation tests.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch http2-ipv6-authority-11895

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 Infer (1.2.0)

src/flb_http_client_http2.c

src/flb_http_client_http2.c:29:10: fatal error: 'fluent-bit/flb_info.h' file not found
29 | #include <fluent-bit/flb_info.h>
| ^~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
Error: the following clang command did not run successfully:
/opt/infer-linux-x86_64-v1.2.0/lib/infer/facebook-clang-plugins/clang/install/bin/clang-18
@/tmp/coderabbit-infer/a7e5c4044c6a1706fa03447cff2474c276e83c52-b6489214243af2c2/tmp/clang_command_.tmp.918197.txt
++Contents of '/tmp/coderabbit-infer/a7e5c4044c6a1706fa03447cff2474c276e83c52-b6489214243af2c2/tmp/clang_command_.tmp.918197.txt':
"-cc1" "-load"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../../facebook-clang-plugins/libtooling/build/FacebookClangPlugin.dylib"
"-add-plugin" "BiniouASTExporter" "-plugin-arg-BiniouASTExporter" "-"
"-plugin-arg-BiniouASTExporter" "PREPEND_CURRENT_DIR=1"
"-plugin-arg-BiniouASTExporter" "MAX_STRING_SIZE=65535" "-cc1" "-triple"
"x86_64-unknown-linux-gnu" "-emit-obj" "-

... [truncated 746 characters] ...

r-linux-x86_64-v1.2.0/lib/infer/facebook-clang-plugins/clang/install/lib/clang/18/include"
"-internal-isystem" "/usr/local/include" "-internal-isystem"
"/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
"-internal-externc-isystem" "/usr/include/x86_64-linux-gnu"
"-internal-externc-isystem" "/include" "-internal-externc-isystem"
"/usr/include" "-Wno-ignored-optimization-argument" "-Wno-everything"
"-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf"
"-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o"
"/tmp/coderabbit-infer/b6489214243af2c2/file.o" "-x" "c"
"src/flb_http_client_http2.c" "-O0" "-fno-builtin" "-include"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../lib/clang_wrappers/global_defines.h"
"-Wno-everything"

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/flb_http_client_http2.c`:
- Around line 109-123: The IPv6 scoped address handling currently strips the
zone when constructing host_for_authority by copying only the part before '%'
into address_buffer; instead, validate the IPv6 address using the substring
before '%' (using inet_pton on address_buffer) but preserve the original scoped
host (the full host string containing '%' and the scope id) when assigning
*host_for_authority so the emitted :authority keeps the scope suffix. Apply the
same change in the other symmetric block that performs the same
inet_pton/host_for_authority assignment (the second occurrence using
zone_id/host_length/address_buffer/inet_pton/host_for_authority).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a01409cb-bb33-4287-991e-938a58ac62bf

📥 Commits

Reviewing files that changed from the base of the PR and between 4cb3476 and 9e4217d.

📒 Files selected for processing (4)

• src/flb_http_client_http2.c
• tests/integration/requirements.txt
• tests/integration/scenarios/out_opentelemetry/config/out_otel_http2_ipv6_logs.yaml
• tests/integration/scenarios/out_opentelemetry/tests/test_out_opentelemetry_001.py