## Describe your changes
`getInterfaceIndex` in the iOS upstream DNS resolver dereferenced the
result of `net.InterfaceByName` before checking the error, so a missing
interface (e.g. during teardown or renaming) caused a nil-pointer panic
instead of a DNS client error.
The helper now returns a wrapped error before touching the interface;
the only caller, `GetClientPrivate`, already propagates the error.
The helper moved to an un-build-tagged file so it can be unit-tested on
host platforms while remaining available to the iOS build. Added a test
covering the missing-interface path. Verified with the new host test, an
iOS arm64 CGO compile, and `git diff --check`.
## Issue ticket number and link
N/A
## Stack
<!-- branch-stack -->
Standalone PR based on `main`.
### 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)
- [x] This change does **not** modify the public API, gRPC protocols,
functionality behavior, CLI / service flags, or introduce a new feature
— **OR** I have discussed it with the NetBird team beforehand (link the
issue / Slack thread in the description). See
[CONTRIBUTING.md](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTING.md#discuss-changes-with-the-netbird-team-first).
> 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 crash fix in the iOS DNS path; no user-facing behavior or
configuration changes.
### Docs PR URL (required if "docs added" is checked)
N/A
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved handling of network interface lookup failures with clearer
error messages that identify the affected interface.
* Added validation for network interface lookups, including reliable
error handling when an interface cannot be found.
* **Tests**
* Added coverage for both successful interface resolution and
missing-interface scenarios.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
* Make sure our iOS dialer does not get overwritten
* set dial timeout for both clients on ios
---------
Co-authored-by: Pascal Fischer <pascal@netbird.io>
* starting engine by passing file descriptor on engine start
* inject logger that does not compile
* logger and first client
* first working connection
* support for routes and working connection
* small refactor for better code quality in swift
* trying to add DNS
* fix
* updated
* fix route deletion
* trying to bind the DNS resolver dialer to an interface
* use dns.Client.Exchange
* fix metadata send on startup
* switching between client to query upstream
* fix panic on no dns response
* fix after merge changes
* add engine ready listener
* replace engine listener with connection listener
* disable relay connection for iOS until proxy is refactored into bind
* Extract private upstream for iOS and fix function headers for other OS
* Update mock Server
* Fix dns server and upstream tests
* Fix engine null pointer with mobile dependencies for other OS
* Revert back to disabling upstream on no response
* Fix some of the remarks from the linter
* Fix linter
* re-arrange duration calculation
* revert exported HostDNSConfig
* remove unused engine listener
* remove development logs
* refactor dns code and interface name propagation
* clean dns server test
* disable upstream deactivation for iOS
* remove files after merge
* fix dns server darwin
* fix server mock
* fix build flags
* move service listen back to initialize
* add wgInterface to hostManager initialization on android
* fix typo and remove unused function
* extract upstream exchange for ios and rest
* remove todo
* separate upstream logic to ios file
* Fix upstream test
* use interface and embedded struct for upstream
* set properly upstream client
* remove placeholder
* remove ios specific attributes
* fix upstream test
* merge ipc parser and wg configurer for mobile
* fix build annotation
* use json for DNS settings handover through gomobile
* add logs for DNS json string
* bring back check on ios for private upstream
* remove wrong (and unused) line
* fix wrongly updated comments on DNSSetting export
---------
Co-authored-by: Maycon Santos <mlsmaycon@gmail.com>
