## Describe your changes
`isValidAccessToken` only decodes the JWT payload and checks the
audience
claim, but its name suggested full token validation. Rename it to
`validateTokenAudience` and document what it does: a client-side
audience/shape
check on a token just obtained from the IdP over TLS. Token authenticity
is
enforced server-side by the management server, which verifies the
signature
against the IdP's JWKS (`shared/auth/jwt/validator.go`) on every
request.
Also harden the parser: a non-empty token lacking the three-part JWT
structure
caused an index-out-of-range panic (`strings.Split(token, ".")[1]`); the
shape
is now validated first. `parseEmailFromIDToken` is documented as
best-effort UX
data (login hint/display), never used for authorization. Added tests for
audience matching, malformed tokens, and the panic regression.
Changes:
- Rename `isValidAccessToken` → `validateTokenAudience`; document that
it does
not verify the signature and that authenticity is enforced server-side.
- Fix an index-out-of-range panic on a non-empty token lacking JWT
structure
(`strings.Split(token, ".")[1]`) by validating the three-part shape
first.
- Document `parseEmailFromIDToken` as best-effort/unverified, used only
for the
login-hint/display UX, never for an authorization decision.
- Add `util_test.go` covering audience matching (string and array),
missing
audience, malformed payloads, and the panic regression.
## Issue ticket number and link
Internal cleanup: rename a misleadingly-named client-side helper and
harden JWT
parsing against malformed input (`client/internal/auth/util.go`).
## Stack
- `0.74.7-branch` - ⚠️ No PR associated with branch <!--
branch-stack -->
- \#6806 :point\_left:
### Checklist
- [x] Is it a bug fix
- [ ] Is a typo/documentation fix
- [ ] Is a feature enhancement
- [ ] It is a refactor
- [x] Created tests that fail without the change (if possible)
> By submitting this pull request, you confirm that you have read and
agree to the terms of the [Contributor License
Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md).
## Documentation
Select exactly one:
- [ ] I added/updated documentation for this change
- [x] Documentation is **not needed** for this change (explain why)
Internal client-side helper rename plus a panic hardening fix. No public
API,
gRPC, CLI/service flag, or configuration change; token authenticity
enforcement
(server-side JWKS verification) is unchanged.
### Docs PR URL (required if "docs added" is checked)
Paste the PR link from <https://github.com/netbirdio/docs> here:
N/A
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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **Bug Fixes**
- Improved access-token audience validation during device and PKCE
authentication flows.
- Malformed tokens now return clear validation errors instead of risking
runtime failures.
- Added support for validating both string and array audience claims.
- **Tests**
- Added coverage for malformed tokens, invalid claims, missing
audiences, and panic prevention.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
The use of reflection should generally be minimized in Go code because
it can make the code less readable, less type-safe, and potentially slower.
In this particular case we can simply rely on type switch.
* shutdown the pkce server on user cancellation
* Refactor openURL to exclusively manage authentication flow instructions and browser launching
* Refactor authentication flow initialization based on client OS
The NewOAuthFlow method now first checks the operating system and if it is a non-desktop Linux, it opts for Device Code Flow. PKCEFlow is tried first and if it fails, then it falls back on Device Code Flow. If both unsuccessful, the authentication process halts and error messages have been updated to provide more helpful feedback for troubleshooting authentication errors
* Replace log-based Linux desktop check with process check
To verify if a Linux OS is running a desktop environment in the Authentication utility, the log-based method that checks the XDG_CURRENT_DESKTOP env has been replaced with a method that checks directly if either X or Wayland display server processes are running. This method is more reliable as it directly checks for the display server process rather than relying on an environment variable that may not be set in all desktop environments.
* Refactor PKCE Authorization Flow to improve server handling
* refactor check for linux running desktop environment
* Improve server shutdown handling and encapsulate handlers with new server multiplexer
The changes enhance the way the server shuts down by specifying a context with timeout of 5 seconds, adding a safeguard to ensure the server halts even on potential hanging requests. Also, the server's root handler is now encapsulated within a new ServeMux instance, to support multiple registrations of a path
Enhance the user experience by enabling authentication to Netbird using Single Sign-On (SSO) with any Identity Provider (IDP) provider. Current client offers this capability through the Device Authorization Flow, however, is not widely supported by many IDPs, and even some that do support it do not provide a complete verification URL.
To address these challenges, this pull request enable Authorization Code Flow with Proof Key for Code Exchange (PKCE) for client logins, which is a more widely adopted and secure approach to facilitate SSO with various IDP providers.
