Add rudimentary NetworkSettings generation

Apple/NetworkExtension/NetworkSettingsConverter.swift

@@ -0,0 +1,56 @@
+//
+//  NetworkSettingsConverter.swift
+//  NetworkExtension
+//
+//  Created by Jett Chen on 2023/7/7.
+//
+
+import Foundation
+import NetworkExtension
+
+public struct TunCrateNetworkSettings {
+    let addr: Int64
+    let netmask: Int64
+    let mtu: Int32
+}
+
+extension TunCrateNetworkSettings {
+    var decodedIPv4Addr: String? {
+        return decodeIPv4(addr)
+    }
+
+    var decodedIPv4Netmask: String? {
+        return decodeIPv4(netmask)
+    }
+
+    var decodedMTU: Int? {
+        return mtu >= 0 ? Int(mtu) : nil
+    }
+
+    private func decodeIPv4(_ addr: Int64) -> String? {
+        if addr < 0 {
+            return nil
+        }
+        let bytes = (
+            UInt8((addr & 0xFF000000) >> 24),
+            UInt8((addr & 0x00FF0000) >> 16),
+            UInt8((addr & 0x0000FF00) >> 8),
+            UInt8(addr & 0x000000FF)
+        )
+        return "\(bytes.0).\(bytes.1).\(bytes.2).\(bytes.3)"
+    }
+    
+    func generateNetworkSettings() -> NEPacketTunnelNetworkSettings {
+            let neSettings = NEPacketTunnelNetworkSettings()
+
+            if let addr = decodedIPv4Addr, let netmask = decodedIPv4Netmask {
+                neSettings.ipv4Settings = NEIPv4Settings(addresses: [addr], subnetMasks: [netmask])
+            }
+            if let mtuValue = decodedMTU {
+                neSettings.mtu = NSNumber(value: mtuValue)
+            }
+            return neSettings
+        }
+
+}
+

Apple/NetworkExtension/PacketTunnelProvider.swift

@@ -4,7 +4,9 @@ import OSLog
 
 class PacketTunnelProvider: NEPacketTunnelProvider {
     let logger = Logger(subsystem: "com.hackclub.burrow", category: "General")
+    
     override func startTunnel(options: [String: NSObject]?, completionHandler: @escaping (Error?) -> Void) {
+        libburrow.initialize_oslog()
         let fild = libburrow.retrieve()
         if fild == -1 {
             // Not sure if this is the right way to return an error
@@ -17,6 +19,8 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
             completionHandler(err)
         }
         logger.info("fd: \(fild)")
+        let networkSettings = genNetSec(fild: fild)
+        logger.info("Network Settings: - ipv4:\(networkSettings.ipv4Settings) -mtu: \(networkSettings.mtu)")
         completionHandler(nil)
     }
 
@@ -24,6 +28,14 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         completionHandler()
     }
 
+    func genNetSec(fild: Int32) -> NEPacketTunnelNetworkSettings {
+        logger.debug("getting Network settings with fild \(fild) ...")
+        let settings = libburrow.getNetworkSettings(fild)
+        logger.debug("genNetSec Called: \n ipv4: \(settings.ipv4_addr) \n netmask: \(settings.ipv4_netmask) \n mtu: \(settings.mtu)")
+        let tNetworksettings = TunCrateNetworkSettings(addr: settings.ipv4_addr, netmask: settings.ipv4_netmask, mtu: settings.mtu)
+        return tNetworksettings.generateNetworkSettings()
+    }
+
     override func handleAppMessage(_ messageData: Data, completionHandler: ((Data?) -> Void)?) {
         if let handler = completionHandler {
             handler(messageData)

Apple/NetworkExtension/libburrow/libburrow.h

@@ -1 +1,11 @@
+#include <stdint.h>
 int retrieve();
+
+typedef struct {
+    int64_t ipv4_addr;
+    int64_t ipv4_netmask;
+    int32_t mtu;
+} NetWorkSettings;
+
+NetWorkSettings getNetworkSettings(int);
+void initialize_oslog();