VPN: Bring up the tunnel

The app figures out all settings and passes them in the
'options' parameter of startTunnel().

The network extension just takes them as is and just plugs the supplied
values into the right places.

Signed-off-by: Roopesh Chander <roop@roopc.net>

2 files changed, 183 insertions, 1 deletions

diff --git a/WireGuard/WireGuard/VPN/PacketTunnelOptionsGenerator.swift b/WireGuard/WireGuard/VPN/PacketTunnelOptionsGenerator.swift
new file mode 100644
index 0000000..e3ecb3c
--- /dev/null
+++ b/WireGuard/WireGuard/VPN/PacketTunnelOptionsGenerator.swift
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: MIT
+// Copyright © 2018 WireGuard LLC. All rights reserved.
+
+import Foundation
+import Network
+
+class PacketTunnelOptionsGenerator {
+    static func generateOptions(from tc: TunnelConfiguration,
+                                withResolvedEndpoints resolvedEndpoints: [Endpoint?]) -> [String:NSObject] {
+        var options: [String:NSObject] = [:]
+
+        // Interface name
+
+        options[.interfaceName] = tc.interface.name as NSObject
+
+        // WireGuard settings
+
+        var wgSettings = ""
+        let privateKey = tc.interface.privateKey.hexEncodedString()
+        wgSettings.append("private_key=\(privateKey)\n")
+        if let listenPort = tc.interface.listenPort {
+            wgSettings.append("listen_port=\(listenPort)\n")
+        }
+        if (tc.peers.count > 0) {
+            wgSettings.append("replace_peers=true\n")
+        }
+        assert(tc.peers.count == resolvedEndpoints.count)
+        for (i, peer) in tc.peers.enumerated() {
+            wgSettings.append("public_key=\(peer.publicKey.hexEncodedString())\n")
+            if let preSharedKey = peer.preSharedKey {
+                wgSettings.append("preshared_key=\(preSharedKey.hexEncodedString())\n")
+            }
+            if let endpoint = resolvedEndpoints[i] {
+                if case .name(_, _) = endpoint.host { assert(false, "Endpoint is not resolved") }
+                wgSettings.append("endpoint=\(endpoint.stringRepresentation())\n")
+            }
+            let persistentKeepAlive = peer.persistentKeepAlive ?? 0
+            wgSettings.append("persistent_keepalive_interval=\(persistentKeepAlive)\n")
+            if (!peer.allowedIPs.isEmpty) {
+                wgSettings.append("replace_allowed_ips=true\n")
+                for ip in peer.allowedIPs {
+                    wgSettings.append("allowed_ip=\(ip.stringRepresentation())\n")
+                }
+            }
+        }
+
+        options[.wireguardSettings] = wgSettings as NSObject
+
+        // Remote address
+
+        let remoteAddress: String
+        if let firstEndpoint = resolvedEndpoints.compactMap({ $0 }).first {
+            switch (firstEndpoint.host) {
+            case .ipv4(let address):
+                remoteAddress = "\(address)"
+            case .ipv6(let address):
+                remoteAddress = "\(address)"
+            default:
+                fatalError("Endpoint must be resolved")
+            }
+        } else {
+            // We don't have any peer with an endpoint
+            remoteAddress = ""
+        }
+
+        options[.remoteAddress] = remoteAddress as NSObject
+
+        // DNS
+
+        options[.dnsServers] = tc.interface.dns.map { $0.stringRepresentation() } as NSObject
+
+        // MTU
+
+        options[.mtu] = NSNumber(value: tc.interface.mtu ?? 0) // 0 implies auto-MTU
+
+        // Addresses from interface addresses
+
+        var ipv4Addresses: [String] = []
+        var ipv4SubnetMasks: [String] = []
+
+        var ipv6Addresses: [String] = []
+        var ipv6NetworkPrefixLengths: [NSNumber] = []
+
+        for addressRange in tc.interface.addresses {
+            if (addressRange.address is IPv4Address) {
+                ipv4Addresses.append("\(addressRange.address)")
+                ipv4SubnetMasks.append(ipv4SubnetMaskString(of: addressRange))
+            } else if (addressRange.address is IPv6Address) {
+                ipv6Addresses.append("\(addressRange.address)")
+                ipv6NetworkPrefixLengths.append(NSNumber(value: addressRange.networkPrefixLength))
+            }
+        }
+
+        options[.ipv4Addresses] = ipv4Addresses as NSObject
+        options[.ipv4SubnetMasks] = ipv4SubnetMasks as NSObject
+
+        options[.ipv6Addresses] = ipv6Addresses as NSObject
+        options[.ipv6NetworkPrefixLengths] = ipv6NetworkPrefixLengths as NSObject
+
+        // Included routes from AllowedIPs
+
+        var ipv4IncludedRouteAddresses: [String] = []
+        var ipv4IncludedRouteSubnetMasks: [String] = []
+
+        var ipv6IncludedRouteAddresses: [String] = []
+        var ipv6IncludedRouteNetworkPrefixLengths: [NSNumber] = []
+
+        for peer in tc.peers {
+            for addressRange in peer.allowedIPs {
+                if (addressRange.address is IPv4Address) {
+                    ipv4IncludedRouteAddresses.append("\(addressRange.address)")
+                    ipv4IncludedRouteSubnetMasks.append(ipv4SubnetMaskString(of: addressRange))
+                } else if (addressRange.address is IPv6Address) {
+                    ipv6IncludedRouteAddresses.append("\(addressRange.address)")
+                    ipv6IncludedRouteNetworkPrefixLengths.append(NSNumber(value: addressRange.networkPrefixLength))
+                }
+            }
+        }
+
+        options[.ipv4IncludedRouteAddresses] = ipv4IncludedRouteAddresses as NSObject
+        options[.ipv4IncludedRouteSubnetMasks] = ipv4IncludedRouteSubnetMasks as NSObject
+
+        options[.ipv6IncludedRouteAddresses] = ipv6IncludedRouteAddresses as NSObject
+        options[.ipv6IncludedRouteNetworkPrefixLengths] = ipv6IncludedRouteNetworkPrefixLengths as NSObject
+
+        // Excluded routes from endpoints
+
+        var ipv4ExcludedRouteAddresses: [String] = []
+        var ipv4ExcludedRouteSubnetMasks: [String] = []
+
+        var ipv6ExcludedRouteAddresses: [String] = []
+        var ipv6ExcludedRouteNetworkPrefixLengths: [NSNumber] = []
+
+        for endpoint in resolvedEndpoints {
+            guard let endpoint = endpoint else { continue }
+            switch (endpoint.host) {
+            case .ipv4(let address):
+                ipv4ExcludedRouteAddresses.append("\(address)")
+                ipv4ExcludedRouteSubnetMasks.append("255.255.255.255") // A single IPv4 address
+            case .ipv6(let address):
+                ipv6ExcludedRouteAddresses.append("\(address)")
+                ipv6ExcludedRouteNetworkPrefixLengths.append(NSNumber(value: UInt8(128))) // A single IPv6 address
+            default:
+                fatalError()
+            }
+        }
+
+        options[.ipv4ExcludedRouteAddresses] = ipv4ExcludedRouteAddresses as NSObject
+        options[.ipv4ExcludedRouteSubnetMasks] = ipv4ExcludedRouteSubnetMasks as NSObject
+
+        options[.ipv6ExcludedRouteAddresses] = ipv6ExcludedRouteAddresses as NSObject
+        options[.ipv6ExcludedRouteNetworkPrefixLengths] = ipv6ExcludedRouteNetworkPrefixLengths as NSObject
+
+        return options
+    }
+
+    static func ipv4SubnetMaskString(of addressRange: IPAddressRange) -> String {
+        var n: UInt8 = addressRange.networkPrefixLength
+        assert(n <= 32)
+        var components: [UInt8] = []
+        while (n >= 8) {
+            components.append(255)
+            n = n - 8
+        }
+        if (n > 0) {
+            components.append(((1 << n) - 1) << (8 - n))
+        }
+        while (components.count < 4) {
+            components.append(0)
+        }
+        assert(components.count == 4)
+        return components.map { String($0) }.joined(separator: ".")
+    }
+}
+
+private extension Data {
+    func hexEncodedString() -> String {
+        return self.map { String(format: "%02x", $0) }.joined()
+    }
+}
diff --git a/WireGuard/WireGuard/VPN/TunnelsManager.swift b/WireGuard/WireGuard/VPN/TunnelsManager.swift
index 039862d..b4e8231 100644
--- a/WireGuard/WireGuard/VPN/TunnelsManager.swift
+++ b/WireGuard/WireGuard/VPN/TunnelsManager.swift
@@ -277,7 +277,9 @@ class TunnelContainer: NSObject {
             s.startObservingTunnelStatus()
             let session = (s.tunnelProvider.connection as! NETunnelProviderSession)
             do {
-                try session.startTunnel(options: [:]) // TODO: Provide options
+                let tunnelOptions = PacketTunnelOptionsGenerator.generateOptions(
+                    from: tunnelConfiguration, withResolvedEndpoints: endpoints)
+                try session.startTunnel(options: tunnelOptions)
             } catch (let error) {
                 os_log("Failed to activate tunnel: %{public}@", log: OSLog.default, type: .debug, "\(error)")
                 s.onActive = nil