fix: use Foundation Lib for executing pac

Author: Rushabhshroff

ios/Classes/SwiftFlutterSystemProxyPlugin.swift

@@ -11,28 +11,77 @@ public class SwiftFlutterSystemProxyPlugin: NSObject, FlutterPlugin {
   public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
     switch call.method {
     case "getDeviceProxy":
-      let systemProxySettings = CFNetworkCopySystemProxySettings()?.takeUnretainedValue() ?? [:] as CFDictionary
-      result(systemProxySettings as NSDictionary)
-      break
-    case "executePAC":
-      let systemProxySettings = CFNetworkCopySystemProxySettings()?.takeUnretainedValue() ?? [:] as CFDictionary
-      let proxyDict = systemProxySettings as NSDictionary
-      if(proxyDict.value(forKey:"ProxyAutoConfigEnable")as! Bool){
-        let args = call.arguments as! NSDictionary
-        let url = args.value(forKey:"url") as! String
-        let host = args.value(forKey:"host") as! String
-        let js = args.value(forKey:"js") as! String
-        let jsEngine:JSContext = JSContext()
-        jsEngine.evaluateScript(js)
-        let fn = "FindProxyForURL(\"" + url + "\",\""+host+"\")"
-        let proxy = jsEngine.evaluateScript(fn)
-        result(proxy?.toString())
-      }else{
-        result("DIRECT")
-      }
+      let args = call.arguments as! NSDictionary
+      let url = args.value(forKey:"url") as! String
+      var dict:[String:Any] = [:]
+      findProxyFromEnvironment(url: url,callback: { host, port in 
+        dict["host"] = host 
+        dict["port"] = port
+        result(dict)
+      })
       break
     default:
       result(FlutterMethodNotImplemented)
     }
   }
+
+  func findProxyFromEnvironment(url: String,callback: @escaping (_ host:String?,_ port:Int?)->Void) {
+        let proxConfigDict = CFNetworkCopySystemProxySettings()?.takeUnretainedValue() as NSDictionary?
+        if(proxConfigDict != nil){
+            if(proxConfigDict!["ProxyAutoConfigEnable"] as? Int == 1){
+                let pacUrl = proxConfigDict!["ProxyAutoConfigURLString"] as? String
+                let pacContent = proxConfigDict!["ProxyAutoConfigJavaScript"] as? String
+                if(pacContent != nil){
+                    self.handlePacContent(pacContent: pacContent! as String, url: url, callback: callback)
+                }
+                downloadPac(pacUrl: pacUrl!, callback: { pacContent,error in
+                    
+                    if(error != nil){
+                        callback(nil,nil)
+                    }else{
+                        self.handlePacContent(pacContent: pacContent!, url: url, callback: callback)
+                    }
+                })
+            } else if (proxConfigDict!["HTTPEnable"] as? Int == 1){
+                callback((proxConfigDict!["HTTPProxy"] as? String),(proxConfigDict!["HTTPPort"] as? Int))
+            } else if ( proxConfigDict!["HTTPSEnable"] as? Int == 1){
+                callback((proxConfigDict!["HTTPSProxy"] as? String),(proxConfigDict!["HTTPSPort"] as? Int))
+            } else {
+                callback(nil,nil)
+            }
+        }
+    }
+    
+    func handlePacContent(pacContent: String,url: String, callback:(_ host:String?,_ port:Int?)->Void){
+        let proxies = CFNetworkCopyProxiesForAutoConfigurationScript(pacContent as CFString, CFURLCreateWithString(kCFAllocatorDefault, url as CFString, nil), nil)!.takeUnretainedValue() as? [[CFString: Any]] ?? [];
+        if(proxies.count > 0){
+            let proxy = proxies.first{$0[kCFProxyTypeKey] as! CFString == kCFProxyTypeHTTP || $0[kCFProxyTypeKey] as! CFString == kCFProxyTypeHTTPS}
+            if(proxy != nil){
+                let host = proxy?[kCFProxyHostNameKey] ?? nil
+                let port = proxy?[kCFProxyPortNumberKey] ?? nil
+                callback(host as? String,port as? Int)
+            }else{
+               callback(nil,nil)
+            }
+        }else{
+            callback(nil,nil)
+        }
+    }
+    
+    
+    func downloadPac(pacUrl:String, callback:@escaping (_ pacContent:String?,_ error: Error?)->Void) {
+        var pacContent:String = ""
+        let config = URLSessionConfiguration.default
+        config.connectionProxyDictionary = [AnyHashable: Any]()
+        let session = URLSession.init(configuration: config,delegate: nil,delegateQueue: OperationQueue.current)
+        session.dataTask(with: URL(string: pacUrl)!, completionHandler: { data, response, error in
+            if(error != nil){
+                callback(nil,error)
+            }
+            pacContent = String(bytes: data!,encoding: String.Encoding.utf8)!
+            callback(pacContent,nil)
+        }).resume()
+
+    }
+
 }