public_key: Fix encoding and decoding extensions

[dgud]

Extensions was not looked up correctly they are split depending on extension structure, currently three different functions.

Clean up code in public_key to lookup the extensions before enc/decoding them so that all supported extensions will be available.

Also remove the type that where extensions and couldn't be called directly, SubjectAltName and FreshestCRL.

Test encode/decode all them.

Fixes #10404

[github-actions]

CT Test Results

  2 files   17 suites   6m 53s ⏱️
292 tests 286 ✅ 6 💤 0 ❌
308 runs  302 ✅ 6 💤 0 ❌

Results for commit 0de5a61.

♻️ This comment has been updated with latest results.

To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass.

See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally.

Artifacts

• Complete CT logs (Download Logs)
• HTML Documentation (Download HTML Docs)
• Windows Installer

// Erlang/OTP Github Action Bot

[Copilot]

Pull request overview

This PR refactors the certificate extension encoding and decoding logic in the public_key module to fix issues where extensions were not being looked up correctly. The changes unify extension handling through a cleaner lookup mechanism and add comprehensive test coverage for all supported extension types.

Key Changes

• Refactored der_encode/2 and der_decode/2 to use a two-tier lookup: first checking direct ASN.1 module mappings via get_asn1_module/1, then falling back to extension-specific handling via ext_oid/1
• Enhanced extension_id/1 to return a 4-tuple {Module, DecodeFunc, EncodeFunc, ExtensionName} containing all metadata needed for extension processing, enabling proper routing to the correct ASN.1 decoder/encoder functions
• Removed direct ASN.1 module mappings for SubjectAltName and FreshestCRL from get_asn1_module/1, allowing them to be handled exclusively through the extension infrastructure
• Added comprehensive test ext_encoding/1 that validates encode/decode round-trips for 22 different extension types

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/public_key/test/public_key_SUITE.erl	Added comprehensive test ext_encoding/1 covering 22 extension types and error handling for unknown types
lib/public_key/src/public_key.erl	Refactored der_encode/2 and der_decode/2 to use unified extension lookup, removed hardcoded extension type guards, added catch-all clause to get_asn1_module/1, and improved error reporting
lib/public_key/src/pubkey_cert_records.erl	Refactored extension_id/1 to return 4-tuple with module and function metadata, updated decode_extensions/2 and encode_extensions/1 to use new tuple structure

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.