net/dns: align Apple resolver scoping with search-domain behavior

Browse Source

Apple tunnels derive global search domains from match domains. Scope
simple iOS and sandboxed macOS configurations to the full MagicDNS route
set; keep custom split resolvers and uncovered forward/PTR records behind
a primary resolver. Respect scoping controls and reject unsafe fallback
when base DNS cannot be read.

Add mode-selection and reverse-coverage tests for both Apple platforms.

RELNOTE: Fix MagicDNS routing and split-DNS search scoping on Apple clients.

Updates tailscale/corp#48693

Change-Id: I50b5641db466f77c19f911255748e12a10d0a5fe
Signed-off-by: James Tucker <james@tailscale.com>

...

This commit is contained in:

500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f