Feat/add ping idp provider

[jadiaconu]

Description

This pull request adds support for Ping Identity as an OIDC provider. The changes introduce the detection and handling of Ping providers throughout the OIDC parser and ID generation logic, and improve claim extraction from JWTs to handle Ping’s conventions.

Ping Identity support:

• Added PingProviderName constant and logic to detect Ping providers based on hostname suffixes in pkg/oidc/provider.go and pkg/oidc/parser.go. [1] [2] [3]
• Introduced PingScheme for ID generation and updated the provider-to-scheme mapping in internal/node/id_generator.go. [1] [2]

OIDC claim extraction improvements:

• Enhanced JWT subject extraction to fall back to cid or client_id claims if sub is missing, improving compatibility with Ping and similar providers in pkg/oidc/parser.go.

Code consistency:

• Refactored constants for cache settings in pkg/oidc/parser.go to use a grouped const block for clarity.

Type of Change

• Bugfix
• New Feature
• Breaking Change
• Refactor
• Documentation
• Other (please describe)

Checklist

• I have read the contributing guidelines
• Existing issues have been referenced (where applicable)
• I have verified this change is not present in other open pull requests
• Functionality is documented
• All code style checks pass
• New code contribution is covered by automated tests
• All new and existing tests pass

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[Copilot]

Pull request overview

This PR adds support for Ping Identity as an OIDC provider, introducing detection logic for Ping domains and enhancing JWT claim extraction to support alternative subject claims (cid, client_id) as fallbacks.

Changes:

• Added Ping Identity provider detection and ID generation scheme
• Enhanced JWT claim extraction to support cid and client_id as fallback subject claims
• Refactored constant declarations for improved code organization

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
pkg/oidc/provider.go	Adds isPing() function to detect Ping Identity providers based on hostname suffixes
pkg/oidc/parser.go	Adds PingProviderName constant, refactors cache constants into grouped block, and enhances subject claim extraction with fallback logic
internal/node/id_generator.go	Adds PingScheme constant and mapping for Ping provider in ID generation

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[Copilot]

The new PingProviderName case in the switch statement lacks test coverage. The existing tests in id_service_test.go cover other providers like DuoProviderName and SelfProviderName, but there's no test case verifying that Ping provider generates IDs with the "PING-" prefix. Consider adding a test similar to TestGenerateID_Should_Not_Return_Errors but using oidc.PingProviderName to verify the ID generation for Ping providers.