Add a reversible IP interface metric boundary to `lanparty-client-route`. The
crate can now read an IPv4 or IPv6 interface metric snapshot and temporarily set
a manual interface metric with an RAII guard that restores the previous metric
and automatic-metric state on drop.
This prepares the TAP metric handling without wiring policy into the Windows
client yet. Default-route disabling is captured in snapshots for diagnostics and
future decisions, but this slice deliberately changes only `UseAutomaticMetric`
and `Metric`.
Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- cargo check -p lanparty-client-route --target x86_64-pc-windows-msvc
- cargo clippy -p lanparty-client-route --target x86_64-pc-windows-msvc --all-targets -- -D warnings
- git diff --check
Refs: PLAN.md
Refs: https://learn.microsoft.com/en-us/windows-hardware/drivers/network/initializeipinterfaceentry
Refs: https://learn.microsoft.com/en-us/windows/win32/api/netioapi/nf-netioapi-setipinterfaceentry
Add a small route-crate API that resolves a Windows network adapter GUID into
its interface LUID and index. The TAP adapter discovery already gives us the
NetCfgInstanceId GUID, and the route/metric work needs the corresponding IP
interface identity before it can safely inspect or adjust TAP metrics.
The implementation keeps GUID parsing local and dependency-free, then delegates
the actual identity lookup to Windows IP Helper calls. Non-Windows builds expose
the same API shape with a clear unsupported-platform error.
Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- cargo check -p lanparty-client-route --target x86_64-pc-windows-msvc
- cargo clippy -p lanparty-client-route --target x86_64-pc-windows-msvc --all-targets -- -D warnings
- git diff --check
Refs: PLAN.md
Add the first route-table mutation API to `lanparty-client-route`. Given the
pre-TAP best-route snapshot, the crate can now create a host route for the relay
IP on that same interface and return an RAII guard that deletes the route when
it is dropped.
The route row is initialized with `InitializeIpForwardEntry`, uses a /32 or
/128 destination prefix for the relay IP, preserves the pre-TAP interface
index/LUID, and uses the remembered next hop or an on-link unspecified next hop
when Windows reported no gateway. The guard tracks whether creation actually
succeeded so pure row-construction tests and failed creates do not try to delete
routes they did not install.
This remains a crate-level boundary only. The Windows client still reports the
pre-TAP route but does not yet hold a pin across TAP activation; that is the
next integration slice.
Test Plan:
- cargo fmt --check
- cargo test -p lanparty-client-route
- cargo clippy -p lanparty-client-route --all-targets -- -D warnings
- cargo check -p lanparty-client-route --target x86_64-pc-windows-msvc
- cargo clippy -p lanparty-client-route --target x86_64-pc-windows-msvc --all-targets -- -D warnings
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- git diff --check
Refs: PLAN.md
Refs: https://learn.microsoft.com/en-us/windows-hardware/drivers/network/createipforwardentry2
Refs: https://learn.microsoft.com/en-us/windows-hardware/drivers/network/initializeipforwardentry
Add `lanparty-client-route` as the Win32 boundary for route-table work. The
first API is intentionally read-only: `best_route_to` wraps `GetBestRoute2`
and returns the selected source address, next hop, route prefix, interface
index/LUID, and route metric for a relay destination IP.
This keeps the route-protection work separate from the QUIC client binary, so
we can typecheck the Windows IP Helper calls on this Linux host without pulling
in the `ring` build path that currently blocks full Windows binary checks.
Actual route pinning and metric mutation remain later slices.
Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- cargo check -p lanparty-client-route --target x86_64-pc-windows-msvc
- cargo clippy -p lanparty-client-route --target x86_64-pc-windows-msvc -- -D warnings
- git diff --check
Refs: PLAN.md
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