TunnelKit comes with a simplified Swift/Obj-C implementation of the [OpenVPN®][dep-openvpn] protocol, whose crypto layer is built on top of [OpenSSL 1.1.1][dep-openssl].
The library therefore supports compression framing, just not newer compression. Remember to match server-side compression and framing, otherwise the client will shut down with an error. E.g. if server has `comp-lzo no`, client must use `compressionFraming = .compLZO`.
TunnelKit offers a user-friendly API to the modern [WireGuard®][dep-wireguard] protocol.
### Manual Xcode steps
If you add any `TunnelKitWireGuard*` Swift package to the "Link with binary libraries" section of your app or tunnel extension, you are bound to hit this error:
```
ld: library not found for -lwg-go
```
because part of the WireGuardKit package is based on `make`, which SwiftPM doesn't support yet.
Therefore, make sure to follow the steps below for proper integration:
- Copy `Scripts/build_wireguard_go_bridge.sh` somewhere in your project.
- In Xcode, click File -> New -> Target. Switch to "Other" tab and choose "External Build System".
- Type a name for your target.
- Open the "Info" tab and replace `/usr/bin/make` with `$(PROJECT_DIR)/path/to/build_wireguard_go_bridge.sh` in "Build Tool".
- Switch to "Build Settings" and find SDKROOT. Type in `macosx` if you target macOS, or type in `iphoneos` if you target iOS.
- Locate your tunnel extension target and switch to "Build Phases" tab.
- Locate "Dependencies" section and hit "+" to add the target you have just created.
Make sure to set "Enable Bitcode" (iOS) to NO, otherwise the library [would not be able to link OpenSSL][about-pr-bitcode] (OpenVPN) and the `wg-go` bridge (WireGuard).
Recent versions of Xcode (latest is 13.1) have an issue where the "Frameworks" directory is replicated inside application extensions. This is not a blocker during development, but will prevent your archive from being validated against App Store Connect due to the following error:
ERROR ITMS-90206: "Invalid Bundle. The bundle at '*.appex' contains disallowed file 'Frameworks'."
You will need to add a "Run Script" phase to your main app target where you manually remove the offending folder, i.e.:
Make sure to also update the following constants in the `*ViewController.swift` files, according to your developer account and your target bundle identifiers:
The library is split into several modules, in order to decouple the low-level protocol implementation from the platform-specific bridging, namely the [NetworkExtension][ne-home] VPN framework.
Full documentation of the public interface is available and can be generated by opening the package in Xcode and running "Build Documentation" (Xcode 13).
This component includes convenient classes to control the VPN tunnel from your app without the NetworkExtension headaches. Have a look at `VPNProvider` implementations:
Here you find `NativeProvider`, a generic way to manage a VPN profile based on the native IPSec/IKEv2 protocols. Just wrap a `NEVPNProtocolIPSec` or `NEVPNProtocolIKEv2` object in a `NetworkExtensionVPNConfiguration` and use it to install or connect to the VPN.
As seen in [libsignal-protocol-c][license-signal]:
> Additional Permissions For Submission to Apple App Store: Provided that you are otherwise in compliance with the GPLv3 for each covered work you convey (including without limitation making the Corresponding Source available in compliance with Section 6 of the GPLv3), the Author also grants you the additional permission to convey through the Apple App Store non-source executable versions of the Program as incorporated into each applicable covered work as Executable Versions only under the Mozilla Public License version 2.0 (https://www.mozilla.org/en-US/MPL/2.0/).
