Remove split tunnel interface if split tunneling is disabled

[MarkusPettersson98]

In the current split tunnel design, the split tunnel interface is never destroyed once it has been created. This PR removes the split tunnel interface when split tunneling is disabled, since any potential issues with split tunneling should not affect anyone who disables the feature.

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This change is 

[linear]

DES-1130 Remove split tunnel utun when split tunneling is disabled

[dlon]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @MarkusPettersson98)

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talpid-core/src/split_tunnel/macos/mod.rs line 435 at r1 (raw file):

                vpn_interface,
            } if paths.is_empty() => {
                drop(tun_handle);

We should shut these down gracefully rather than just drop them. See Self::shutdown(). That could probably be called here.

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talpid-core/src/split_tunnel/macos/mod.rs line 512 at r1 (raw file):

                match tun_handle
                    .set_interfaces(default_interface, Some(vpn_interface.clone()))

vpn_interface is shadowed by the old/existing value here.

[MarkusPettersson98]

Reviewable status: 2 of 3 files reviewed, 2 unresolved discussions (waiting on @dlon)

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talpid-core/src/split_tunnel/macos/mod.rs line 435 at r1 (raw file):

Previously, dlon (David Lönnhager) wrote…

We should shut these down gracefully rather than just drop them. See Self::shutdown(). That could probably be called here.

Done

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talpid-core/src/split_tunnel/macos/mod.rs line 512 at r1 (raw file):

Previously, dlon (David Lönnhager) wrote…

vpn_interface is shadowed by the old/existing value here.

Done

[dlon]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[dlon]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @MarkusPettersson98)

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talpid-core/src/split_tunnel/macos/mod.rs line 505 at r2 (raw file):

                                process,
                                tun_handle,
                                vpn_interface,

Previously, the state wasn't altered when failing, but now it seems to receive the new VPN interface. It could probably become out of sync with tun, so might be best to keep the old behavior.

[MarkusPettersson98]

Reviewable status: 2 of 3 files reviewed, 1 unresolved discussion (waiting on @dlon)

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talpid-core/src/split_tunnel/macos/mod.rs line 505 at r2 (raw file):

Previously, dlon (David Lönnhager) wrote…

Previously, the state wasn't altered when failing, but now it seems to receive the new VPN interface. It could probably become out of sync with tun, so might be best to keep the old behavior.

Ah yes, that's a fair point. Reverted that change, so now the old VPN interface is kept upon failure.

[dlon]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved