Addressing a race condition in the Wireguard Tunnel manager

[alexlovelltroy]

Description

This pull request improves the thread-safety and reliability of the InterfaceManager in the wgtunnel package, especially under concurrent operations. The main changes include fixing a concurrency bug in IP allocation, ensuring the internal peers map cannot be mutated by callers, and adding comprehensive tests for these scenarios.

Thread safety and concurrency fixes:

• Changed IpForPeer to use a write lock (Lock instead of RLock) to prevent race conditions when allocating and storing peer IPs concurrently.
• Updated GetPeers to return a copy of the internal peers map using maps.Copy, ensuring callers cannot mutate the internal state. [1] [2]

Testing improvements:

• Added pkg/wgtunnel/tunnels_test.go with tests for concurrent IP allocation (TestIpForPeerConcurrentAllocations) and for verifying that GetPeers returns a safe copy (TestGetPeersReturnsCopy).

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• I have updated the relevant documentation (CLI examples, man pages, README, other docs, etc.)
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Dependency update

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[travisbcotton]

I think this is fine. Approved outside the linting failures