Add negative leak test for iOS

[niklasberglund]

Adds basic leak tests which makes sure that traffic to a specific host goes through tunnel. There's a lot of room for improvement in how the window for packet capture is determined. Since local APIs cannot be accessed once connected to a relay the packet capture is started before connecting to relay, and stopped after disconnecting. Then a few seconds is trimmed from the beginning and end of the packet capture in order to not get any packet capture from when the tunnel connection was not up.

The changes in this PR can be tested by running the end to end tests testNoLeak and testShouldLeak.

Note: there's a known issue with the traffic generation. After setting up a tunnel connection all the connections for dummy traffic are blocked.

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This change is 

[niklasberglund]

Reviewable status: 0 of 13 files reviewed, 1 unresolved discussion (waiting on @pinkisemils)

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ios/MullvadVPNUITests/Networking/StreamCollection.swift line 160 at r1 (raw file):

        }

        return DateInterval(start: startDate!, end: endDate!)

Left some illegal force unwrapping in this function which should probably be fixed 👮

[niklasberglund]

Reviewable status: 0 of 13 files reviewed, 2 unresolved discussions (waiting on @pinkisemils)

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ios/MullvadVPNUITests/Base/BaseUITestCase.swift line 110 at r1 (raw file):

        let springboard = XCUIApplication(bundleIdentifier: "com.apple.springboard")

        if springboard.buttons["Allowi"].waitForExistence(timeout: Self.shortTimeout) {

Typo "Allowi"

[niklasberglund]

Reviewable status: 0 of 13 files reviewed, 3 unresolved discussions (waiting on @pinkisemils)

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ios/MullvadVPN.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved line 0 at r1 (raw file):
Restore 😄

[pinkisemils]

Reviewed 3 of 13 files at r1, 7 of 11 files at r2, 3 of 5 files at r3, all commit messages.
Reviewable status: 11 of 15 files reviewed, 5 unresolved discussions (waiting on @niklasberglund)

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ios/MullvadVPNUITests/LeakTests.swift line 87 at r3 (raw file):

        let capturedStreams = stopPacketCapture()
        LeakCheck.assertNoLeaks(streams: capturedStreams, rules: [NoTrafficToHostLeakRule(host: targetIPAddress)])

assertNoLeaks implies that it shouldn't leak, no? Or am I reading this wrong? :)

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ios/MullvadVPNUITests/Base/BaseUITestCase.swift line 225 at r3 (raw file):

            // If there's a an active session due to cancelled/failed test run make sure to end it
            if packetCaptureSessionIsActive {

S

[pinkisemils]

Reviewed 1 of 13 files at r1, 1 of 5 files at r3.
Reviewable status: 13 of 15 files reviewed, 5 unresolved discussions (waiting on @niklasberglund)

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ios/MullvadVPNUITests/Networking/Networking.swift line 32 at r3 (raw file):

class Networking {
    static func getIPAddress() throws -> String {
        var ipAddress: String

We actually have an API now to get the correct IP address here, there are devices in the office where en0 is not the WiFi interface. A simple GET on /own-ip will return the IP of the device.

[niklasberglund]

Reviewable status: 7 of 18 files reviewed, 3 unresolved discussions (waiting on @pinkisemils)

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ios/MullvadVPNUITests/LeakTests.swift line 87 at r3 (raw file):

Previously, pinkisemils (Emīls Piņķis) wrote…

assertNoLeaks implies that it shouldn't leak, no? Or am I reading this wrong? :)

Haha yes you're right. Fixed

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ios/MullvadVPNUITests/Base/BaseUITestCase.swift line 225 at r3 (raw file):

Previously, pinkisemils (Emīls Piņķis) wrote…

S

Did you mean to write something more? 😊

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ios/MullvadVPNUITests/Networking/Networking.swift line 32 at r3 (raw file):

Previously, pinkisemils (Emīls Piņķis) wrote…

We actually have an API now to get the correct IP address here, there are devices in the office where en0 is not the WiFi interface. A simple GET on /own-ip will return the IP of the device.

Nice, using it instead now. There was a function to get IP address using the API in FirewallClient but I created a super class TestRouterAPIClient which all other "clients" inherit from. Moved the get IP address function to there because it's not firewall specific.