filter_geoip2: fix lookup key comparison by sbruder · Pull Request #12237 · fluent/fluent-bit

sbruder · 2026-08-05T20:10:50Z

This patch fixes the problem that when a key with the same prefix as the lookup key existed, the filter could choose the wrong one, as the comparison was limited to the length of the specified lookup key.

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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.

Output prior to the change

Attachments:

$ echo '{"address": "8.8.8.8", "bddress_type": "ipv4"}'"\n"'{"address": "8.8.8.8", "address_type": "ipv4"}' | podman run --rm -i -v /tmp/dbip-asn-lite.mmdb:/tmp/dbip-asn-lite.mmdb fluent-bit /fluent-bit/bin/fluent-bit -i stdin -F geoip2 -m "*" -p database=/tmp/dbip-asn-lite.mmdb -p lookup_key=address -p record="address_asn address %{autonomous_system_number}" -o stdout
Fluent Bit v5.1.0
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


[2026/08/05 20:07:05.750] [ info] [fluent bit] version=5.1.0, commit=fe293d4270, pid=1
[2026/08/05 20:07:05.751] [ info] [storage] ver=1.5.4, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2026/08/05 20:07:05.751] [ info] [simd    ] SSE2
[2026/08/05 20:07:05.751] [ info] [cmetrics] version=2.2.1
[2026/08/05 20:07:05.751] [ info] [ctraces ] version=0.7.1
[2026/08/05 20:07:05.751] [ info] [input:stdin:stdin.0] initializing
[2026/08/05 20:07:05.751] [ info] [input:stdin:stdin.0] storage_strategy='memory' (memory only)
[2026/08/05 20:07:05.751] [ info] [sp] stream processor started
[2026/08/05 20:07:05.751] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2026/08/05 20:07:05.751] [ info] [output:stdout:stdout.0] worker #0 started
[2026/08/05 20:07:05.768] [error] [filter:geoip2:geoip2.0] getaddrinfo failed: Name or service not known
[2026/08/05 20:07:05.768] [ warn] [input:stdin:stdin.0] end of file (stdin closed by remote end)
[2026/08/05 20:07:05.768] [ warn] [engine] service will shutdown in max 5 seconds
[2026/08/05 20:07:05.768] [ info] [engine] pausing all inputs..
[0] stdin.0: [[1785960425.768110083, {}], {"address"=>"8.8.8.8", "bddress_type"=>"ipv4", "address_asn"=>15169}]
[1] stdin.0: [[1785960425.768117527, {}], {"address"=>"8.8.8.8", "address_type"=>"ipv4", "address_asn"=>nil}]
[2026/08/05 20:07:06.562] [ info] [engine] service has stopped (0 pending tasks)
[2026/08/05 20:07:06.562] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2026/08/05 20:07:06.562] [ info] [output:stdout:stdout.0] thread worker #0 stopped

Output after the change

$ echo '{"address": "8.8.8.8", "bddress_type": "ipv4"}'"\n"'{"address": "8.8.8.8", "address_type": "ipv4"}' | podman run --rm -i -v /tmp/dbip-asn-lite.mmdb:/tmp/dbip-asn-lite.mmdb fluent-bit /fluent-bit/bin/fluent-bit -i stdin -F geoip2 -m "*" -p database=/tmp/dbip-asn-lite.mmdb -p lookup_key=address -p record="address_asn address %{autonomous_system_number}" -o stdout 
Fluent Bit v5.1.0
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


[2026/08/05 20:08:31.055] [ info] [fluent bit] version=5.1.0, commit=fe293d4270, pid=1
[2026/08/05 20:08:31.056] [ info] [storage] ver=1.5.4, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2026/08/05 20:08:31.056] [ info] [simd    ] SSE2
[2026/08/05 20:08:31.056] [ info] [cmetrics] version=2.2.1
[2026/08/05 20:08:31.056] [ info] [ctraces ] version=0.7.1
[2026/08/05 20:08:31.056] [ info] [input:stdin:stdin.0] initializing
[2026/08/05 20:08:31.056] [ info] [input:stdin:stdin.0] storage_strategy='memory' (memory only)
[2026/08/05 20:08:31.056] [ info] [sp] stream processor started
[2026/08/05 20:08:31.056] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2026/08/05 20:08:31.056] [ info] [output:stdout:stdout.0] worker #0 started
[2026/08/05 20:08:31.068] [ warn] [input:stdin:stdin.0] end of file (stdin closed by remote end)
[2026/08/05 20:08:31.068] [ warn] [engine] service will shutdown in max 5 seconds
[2026/08/05 20:08:31.068] [ info] [engine] pausing all inputs..
[0] stdin.0: [[1785960511.068764694, {}], {"address"=>"8.8.8.8", "bddress_type"=>"ipv4", "address_asn"=>15169}]
[1] stdin.0: [[1785960511.068769403, {}], {"address"=>"8.8.8.8", "address_type"=>"ipv4", "address_asn"=>15169}]
[2026/08/05 20:08:31.561] [ info] [engine] service has stopped (0 pending tasks)
[2026/08/05 20:08:31.562] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2026/08/05 20:08:31.562] [ info] [output:stdout:stdout.0] thread worker #0 stopped

Valgrind output

$ echo '{"address": "8.8.8.8", "bddress_type": "ipv4"}'"\n"'{"address": "8.8.8.8", "address_type": "ipv4"}' | podman run --rm -i -v /tmp/dbip-asn-lite.mmdb:/tmp/dbip-asn-lite.mmdb fluent-bit valgrind --leak-check=full /fluent-bit/bin/fluent-bit -i stdin -F geoip2 -m "*" -p database=/tmp/dbip-asn-lite.mmdb -p lookup_key=address -p record="address_asn address %{autonomous_system_number}" -o stdout
==1== Memcheck, a memory error detector
==1== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al.
==1== Using Valgrind-3.24.0 and LibVEX; rerun with -h for copyright info
==1== Command: /fluent-bit/bin/fluent-bit -i stdin -F geoip2 -m * -p database=/tmp/dbip-asn-lite.mmdb -p lookup_key=address -p record=address_asn\ address\ %{autonomous_system_number} -o stdout
==1== 
Fluent Bit v5.1.0
* Copyright (C) 2015-2026 The Fluent Bit Authors
* Fluent Bit is a CNCF graduated project under the Fluent organization
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |  ___||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   _|___ \ | |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \|  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V //\__/ /\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)\___/


==1== Warning: client switching stacks?  SP change: 0x9114558 --> 0x64ab5c0
==1==          to suppress, use: --max-stackframe=46567320 or greater
==1== Warning: client switching stacks?  SP change: 0x64ab558 --> 0x9114558
==1==          to suppress, use: --max-stackframe=46567424 or greater
==1== Warning: client switching stacks?  SP change: 0x9114558 --> 0x64ab558
==1==          to suppress, use: --max-stackframe=46567424 or greater
==1==          further instances of this message will not be shown.
[0] stdin.0: [[1785960310.971641418, {}], {"address"=>"8.8.8.8", "bddress_type"=>"ipv4", "address_asn"=>15169}]
[1] stdin.0: [[1785960310.975738255, {}], {"address"=>"8.8.8.8", "address_type"=>"ipv4", "address_asn"=>15169}]
[2026/08/05 20:05:10.843] [ info] [fluent bit] version=5.1.0, commit=fe293d4270, pid=1
[2026/08/05 20:05:10.873] [ info] [storage] ver=1.5.4, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2026/08/05 20:05:10.874] [ info] [simd    ] SSE2
[2026/08/05 20:05:10.874] [ info] [cmetrics] version=2.2.1
[2026/08/05 20:05:10.875] [ info] [ctraces ] version=0.7.1
[2026/08/05 20:05:10.886] [ info] [input:stdin:stdin.0] initializing
[2026/08/05 20:05:10.887] [ info] [input:stdin:stdin.0] storage_strategy='memory' (memory only)
[2026/08/05 20:05:10.956] [ info] [sp] stream processor started
[2026/08/05 20:05:10.958] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2026/08/05 20:05:11.009] [ warn] [input:stdin:stdin.0] end of file (stdin closed by remote end)
[2026/08/05 20:05:11.017] [ warn] [engine] service will shutdown in max 5 seconds
[2026/08/05 20:05:11.018] [ info] [engine] pausing all inputs..
[2026/08/05 20:05:11.024] [ info] [output:stdout:stdout.0] worker #0 started
[2026/08/05 20:05:11.569] [ info] [engine] service has stopped (0 pending tasks)
[2026/08/05 20:05:11.580] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2026/08/05 20:05:11.583] [ info] [output:stdout:stdout.0] thread worker #0 stopped
==1== 
==1== HEAP SUMMARY:
==1==     in use at exit: 0 bytes in 0 blocks
==1==   total heap usage: 6,407 allocs, 6,407 frees, 1,355,693 bytes allocated
==1== 
==1== All heap blocks were freed -- no leaks are possible
==1== 
==1== For lists of detected and suppressed errors, rerun with: -s
==1== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Summary by CodeRabbit

Bug Fixes
- Improved GeoIP2 lookup matching to compare complete keys without regard to letter casing.
- Prevented partial or prefix matches from returning incorrect results.

This patch fixes the problem that when a key with the same prefix as the lookup key existed, the filter could choose the wrong one, as the comparison was limited to the length of the specified lookup key. Signed-off-by: Simon Bruder <simon@sbruder.de>

coderabbitai · 2026-08-05T20:11:14Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: 1e7cccaf-5439-4899-8ebf-8f812872fc4c

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Reviewing files that changed from the base of the PR and between fe293d4 and 637883d.

📒 Files selected for processing (1)

plugins/filter_geoip2/geoip2.c

📝 Walkthrough

Walkthrough

Changes

GeoIP2 lookup matching

Layer / File(s)	Summary
Update lookup key comparison `plugins/filter_geoip2/geoip2.c`	`prepare_lookup_keys` now uses `flb_sds_casecmp` for case-insensitive full-string matching instead of prefix matching.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Suggested reviewers: cosmo0920

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the lookup key comparison fix in the filter_geoip2 plugin.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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cosmo0920

Looks reasonable but can we add a test case for confirming regressions?

sbruder requested review from cosmo0920 and edsiper as code owners August 5, 2026 20:10

github-actions Bot added the docs-required label Aug 5, 2026

cosmo0920 reviewed Aug 6, 2026

View reviewed changes

sbruder temporarily deployed to pr August 6, 2026 02:20 — with GitHub Actions Inactive

sbruder temporarily deployed to pr August 6, 2026 02:53 — with GitHub Actions Inactive

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filter_geoip2: fix lookup key comparison - #12237

filter_geoip2: fix lookup key comparison#12237
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sbruder:filter-geoip2-fix-lookup-key-cmp

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sbruder commented Aug 5, 2026 •

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