NE: Write log to file

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

WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift

@@ -2,6 +2,7 @@
 // Copyright © 2018 WireGuard LLC. All Rights Reserved.
 
 import NetworkExtension
+import Foundation
 import os.log
 
 enum PacketTunnelProviderError: Error {
@@ -11,6 +12,8 @@ enum PacketTunnelProviderError: Error {
     case coultNotSetNetworkSettings
 }
 
+private var logFileHandle: FileHandle?
+
 /// A packet tunnel provider object.
 class PacketTunnelProvider: NEPacketTunnelProvider {
 
@@ -35,7 +38,11 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
     }
 
     func startTunnel(with tunnelConfiguration: TunnelConfiguration, completionHandler startTunnelCompletionHandler: @escaping (Error?) -> Void) {
-        os_log("Starting tunnel", log: OSLog.default, type: .info)
+
+        // Configure logging
+        configureLogger()
+
+        wg_log(.info, "Starting tunnel")
 
         // Resolve endpoint domains
 
@@ -44,8 +51,8 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         do {
             resolvedEndpoints = try DNSResolver.resolveSync(endpoints: endpoints)
         } catch DNSResolverError.dnsResolutionFailed(let hostnames) {
-            os_log("Starting tunnel failed: DNS resolution failure for %{public}d hostnames (%{public}s)", log: OSLog.default,
-                   type: .error, hostnames.count, hostnames.joined(separator: ", "))
+            wg_log(.error, "Starting tunnel failed: DNS resolution failure")
+            wg_log(.error, "Hostnames for which DNS resolution failed: \(hostnames.joined(separator: ", "))")
             ErrorNotifier.notify(PacketTunnelProviderError.dnsResolutionFailure(hostnames: hostnames), from: self)
             startTunnelCompletionHandler(PacketTunnelProviderError.dnsResolutionFailure(hostnames: hostnames))
             return
@@ -62,11 +69,9 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
 
         // Bring up wireguard-go backend
 
-        configureLogger()
-
         let fd = packetFlow.value(forKeyPath: "socket.fileDescriptor") as! Int32
         if fd < 0 {
-            os_log("Starting tunnel failed: Could not determine file descriptor", log: OSLog.default, type: .error)
+            wg_log(.error, "Starting tunnel failed: Could not determine file descriptor")
             ErrorNotifier.notify(PacketTunnelProviderError.couldNotStartWireGuard, from: self)
             startTunnelCompletionHandler(PacketTunnelProviderError.couldNotStartWireGuard)
             return
@@ -76,7 +81,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         let handle = connect(interfaceName: tunnelConfiguration.interface.name, settings: wireguardSettings, fd: fd)
 
         if handle < 0 {
-            os_log("Starting tunnel failed: Could not start WireGuard", log: OSLog.default, type: .error)
+            wg_log(.error, "Starting tunnel failed: Could not start WireGuard")
             ErrorNotifier.notify(PacketTunnelProviderError.couldNotStartWireGuard, from: self)
             startTunnelCompletionHandler(PacketTunnelProviderError.couldNotStartWireGuard)
             return
@@ -89,7 +94,8 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         let networkSettings: NEPacketTunnelNetworkSettings = packetTunnelSettingsGenerator.generateNetworkSettings()
         setTunnelNetworkSettings(networkSettings) { (error) in
             if let error = error {
-                os_log("Starting tunnel failed: Error setting network settings: %s", log: OSLog.default, type: .error, error.localizedDescription)
+                wg_log(.error, "Starting tunnel failed: Error setting network settings.")
+                wg_log(.error, "Error from setTunnelNetworkSettings: \(error.localizedDescription)")
                 ErrorNotifier.notify(PacketTunnelProviderError.coultNotSetNetworkSettings, from: self)
                 startTunnelCompletionHandler(PacketTunnelProviderError.coultNotSetNetworkSettings)
             } else {
@@ -100,14 +106,34 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
 
     /// Begin the process of stopping the tunnel.
     override func stopTunnel(with reason: NEProviderStopReason, completionHandler: @escaping () -> Void) {
-        os_log("Stopping tunnel", log: OSLog.default, type: .info)
+        wg_log(.info, "Stopping tunnel")
         if let handle = wgHandle {
             wgTurnOff(handle)
         }
+        if let fileHandle = logFileHandle {
+            fileHandle.closeFile()
+        }
         completionHandler()
     }
 
     private func configureLogger() {
+
+        // Setup writing the log to a file
+        if let networkExtensionLogFileURL = FileManager.networkExtensionLogFileURL {
+            let fileManager = FileManager.default
+            let filePath = networkExtensionLogFileURL.path
+            fileManager.createFile(atPath: filePath, contents: nil) // Create the file if it doesn't already exist
+            if let fileHandle = FileHandle(forWritingAtPath: filePath) {
+                logFileHandle = fileHandle
+            } else {
+                os_log("Can't open log file for writing. Log is not saved to file.", log: OSLog.default, type: .error)
+                logFileHandle = nil
+            }
+        } else {
+            os_log("Can't obtain log file URL. Log is not saved to file.", log: OSLog.default, type: .error)
+        }
+
+        // Setup WireGuard logger
         wgSetLogger { (level, msgCStr) in
             let logType: OSLogType
             switch level {
@@ -121,7 +147,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
                 logType = .default
             }
             let msg = (msgCStr != nil) ? String(cString: msgCStr!) : ""
-            os_log("%{public}s", log: OSLog.default, type: logType, msg)
+            wg_log(logType, msg)
         }
     }
 
@@ -130,6 +156,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
             return wgTurnOn(nameGoStr, settingsGoStr, fd)
         }
     }
+
 }
 
 private func withStringsAsGoStrings<R>(_ str1: String, _ str2: String, closure: (gostring_t, gostring_t) -> R) -> R {
@@ -141,3 +168,45 @@ private func withStringsAsGoStrings<R>(_ str1: String, _ str2: String, closure:
         }
     }
 }
+
+private func wg_log(_ type: OSLogType, _ msg: StaticString) {
+    // Write to os log
+    os_log(msg, log: OSLog.default, type: type)
+    // Write to file log
+    let msgString: String = msg.withUTF8Buffer { (ptr: UnsafeBufferPointer<UInt8>) -> String in
+        return String(decoding: ptr, as: UTF8.self)
+    }
+    file_log(type: type, message: msgString)
+}
+
+private func wg_log(_ type: OSLogType, _ msg: String) {
+    // Write to os log
+    os_log("%{public}s", log: OSLog.default, type: type, msg)
+    // Write to file log
+    file_log(type: type, message: msg)
+}
+
+private func file_log(type: OSLogType, message: String) {
+    var msgLine = type.toMessagePrefix() + message
+    if (msgLine.last! != "\n") {
+        msgLine.append("\n")
+    }
+    let data = msgLine.data(using: .utf8)
+    if let data = data, let logFileHandle = logFileHandle {
+        logFileHandle.write(data)
+        logFileHandle.synchronizeFile()
+    }
+}
+
+extension OSLogType {
+    func toMessagePrefix() -> String {
+        switch (self) {
+            case .debug: return "Debug: "
+            case .info: return "Info: "
+            case .error: return "Error: "
+            case .fault: return "Fault: "
+        default:
+            return "Unknown: "
+        }
+    }
+}