ja*: Fix preserve logic to check for any header in fingerprint group#12811
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bneradt merged 1 commit intoapache:masterfrom Jan 29, 2026
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Pull request overview
Updates the JA3 and JA4 fingerprint plugins’ --preserve behavior to operate at the “fingerprint group” level (skip adding all related headers if any already exist), preventing mixed upstream/downstream fingerprint header sets.
Changes:
- JA3 plugin: add group-level “any JA3 header exists” check before adding JA3 headers.
- JA4 plugin: add
--preserveoption plus group-level “any JA4 header exists” check before adding JA4 headers. - Tests/gold files updated to validate group-level preserve behavior for both plugins.
Reviewed changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| plugins/ja3_fingerprint/ja3_fingerprint.cc | Implements group-level preserve logic for JA3 header set. |
| plugins/experimental/ja4_fingerprint/plugin.cc | Adds --preserve option parsing and group-level preserve logic for JA4 headers. |
| tests/gold_tests/pluginTest/ja4_fingerprint/ja4_fingerprint.test.py | Adds test coverage for JA4 --preserve behavior. |
| tests/gold_tests/pluginTest/ja4_fingerprint/ja4_fingerprint.replay.yaml | Extends replay scenarios to validate JA4 preserve cases. |
| tests/gold_tests/pluginTest/ja3_fingerprint/ja3_fingerprint.test.py | Adjusts JA3 test assertions for group-level preserve behavior. |
| tests/gold_tests/pluginTest/ja3_fingerprint/ja3_fingerprint_global.replay.yaml | Updates expected JA3 header presence/absence under preserve. |
| tests/gold_tests/pluginTest/ja3_fingerprint/modify-incoming-proxy.gold | Updates expected internal proxy header output for modify-incoming + preserve. |
| tests/gold_tests/pluginTest/ja3_fingerprint/modify-sent-proxy-remap.gold | Updates expected internal proxy header output for remap configuration. |
| tests/gold_tests/pluginTest/ja3_fingerprint/modify-sent-proxy-global.gold | New gold file for global-plugin internal proxy header output expectations. |
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tests/gold_tests/pluginTest/ja3_fingerprint/ja3_fingerprint.test.py
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jasmine-nahrain
previously approved these changes
Jan 27, 2026
Problem: When --preserve was enabled and a request passed through multiple proxies, each header was checked individually. This could result in mismatched fingerprint data - for example, x-ja3-raw being added by a downstream proxy while x-ja3-sig was preserved from an upstream proxy. Solution: The JA3 and JA4 fingerprint plugins now check if ANY header in a fingerprint group exists before adding headers. If any header in the group exists, ALL headers in that group are skipped. Changes: - ja3_fingerprint: Added group-level checks for JA3 headers - ja4_fingerprint: Added --preserve option and group-level check for JA4 headers - Updated tests to verify group-level preserve behavior
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Problem:
When --preserve was enabled and a request passed through multiple proxies, each header was checked individually. This could result in mismatched fingerprint data - for example, x-ja3-raw being added by a downstream proxy while x-ja3-sig was preserved from an upstream proxy.
Solution:
The JA3 and JA4 fingerprint plugins now check if ANY header in a fingerprint group exists before adding headers. If any header in the group exists, ALL headers in that group are skipped.
Changes: