IIS: fix dead Host header fallback (r->hostname == NULL can never be true)

[A13501350]

Summary

Fixes the Host header fallback being dead code in the IIS module.

r->hostname is set from ConvertUTF16ToUTF8(req->CookedUrl.pHost, ...) (line 840). That helper never returns NULL — on NULL/empty input, zero converted bytes, or conversion failure it returns the literal "" (mymodule.cpp:180-184, :199-202, :226-229); on success it returns a pool-allocated buffer. So r->hostname is always non-NULL, and if(r->hostname == NULL) at line 843 was never true, silently skipping the Host header fallback.

Now the check also triggers on an empty string, so when the request URI carries no host (ordinary HTTP/1.1 GET /path + Host: header) the host is taken from the Host header as intended.

Fixes

Closes #3621

Changed location

• iis/mymodule.cpp:843 — if(r->hostname == NULL) → if(r->hostname == NULL || r->hostname[0] == '\0')

The helper's contract is intentionally left unchanged so the other callers (path_info, args) are unaffected.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 159d3c3a-9f22-4d8b-8d8d-ffc7208c44de

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
1 Accepted issue

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube Cloud