http_client: Restore behavior for dummy http client

[cosmo0920]

Previously, we can use dummy http client wihtout upstream connections.
This is using in out_es plugin's test case for response format checking.

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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

• Bug Fixes
  • Improved null-handling in HTTP client connection setup to prevent crashes when an associated upstream connection is absent; ensures safe initialization for dummy clients.

[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: 2b7beda3-8869-4124-bf4d-6a2989b717b1

📥 Commits

Reviewing files that changed from the base of the PR and between 2e5ba09 and 26242ef.

📒 Files selected for processing (1)

• src/flb_http_client.c

🚧 Files skipped from review as they are similar to previous changes (1)

• src/flb_http_client.c

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📝 Walkthrough

Walkthrough

create_http_client() now treats u_conn as nullable. All reads/writes of u_conn->net or u_conn->upstream->base.net are guarded by if (u_conn). For NULL u_conn the code sets original_net_setup = NULL and zero-initializes request_net_setup to avoid dereferences.

Changes

Cohort / File(s)	Summary
HTTP Client Null Safety src/flb_http_client.c	Guarded accesses to u_conn in create_http_client(); only read u_conn->net / u_conn->upstream->base.net and assign c->u_conn->net when u_conn is non-NULL. For dummy-client (u_conn == NULL) set original_net_setup = NULL and zero-init request_net_setup.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• edsiper
• koleini
• fujimotos

Poem

🐇 I sniffed a null where pointers would creep,
So now I check first before taking a leap.
Net setups stay tidy, no segfaulting night,
Dummy clients rest easy — everything's right. 🎉

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: restoring support for a dummy HTTP client without upstream connections in the http_client module.

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✨ 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 cosmo0920-restore-http-dummy-client-behavior

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[coderabbitai]

🧹 Nitpick comments (1)

src/flb_http_client.c (1)

1019-1039: De-duplicate this connection-binding path.

This null-handling fix looks correct, but it now lives beside a second copy of the same u_conn/net setup in http_client_bind_connection(). That split is likely why the dummy-client path drifted here in the first place. Please extract the shared binding logic so both call sites stay in sync, and reformat the new if/else blocks to the repo’s next-line brace style.

As per coding guidelines, **/*.{c,cpp}: Always use braces for if/else/while/do blocks, with opening braces on the next line.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/flb_http_client.c` around lines 1019 - 1039, Extract the duplicated
u_conn/net binding logic into a single static helper function (e.g.,
bind_request_net_setup or http_client_set_net_binding) that takes the
flb_http_client pointer c and struct flb_upstream_conn *u_conn, moves the null
checks currently around c->u_conn, c->original_net_setup and
c->request_net_setup into that helper, and returns/sets up the dummy-client path
when u_conn is NULL; then replace both call sites (the current new block and
http_client_bind_connection()) to call this helper so they stay in sync,
preserve the exact behavior for the u_conn->net vs u_conn->upstream cases, and
reformat all if/else/while blocks to use next-line opening braces per repo
style.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/flb_http_client.c`:
- Around line 1019-1039: Extract the duplicated u_conn/net binding logic into a
single static helper function (e.g., bind_request_net_setup or
http_client_set_net_binding) that takes the flb_http_client pointer c and struct
flb_upstream_conn *u_conn, moves the null checks currently around c->u_conn,
c->original_net_setup and c->request_net_setup into that helper, and
returns/sets up the dummy-client path when u_conn is NULL; then replace both
call sites (the current new block and http_client_bind_connection()) to call
this helper so they stay in sync, preserve the exact behavior for the
u_conn->net vs u_conn->upstream cases, and reformat all if/else/while blocks to
use next-line opening braces per repo style.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: be5b7fb2-62d1-4499-ba03-757ef1d3d94a

📥 Commits

Reviewing files that changed from the base of the PR and between 63ed88e and 2e5ba09.

📒 Files selected for processing (1)

• src/flb_http_client.c