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Document the solution to the WebView request proxy issue

#Programming357
AI Translation
This post is translated from Chinese into English through AI.View Original
AI-generated summary
The product needs to support user binding with Steam, but due to restrictions, a webview proxy is needed to access the Steam community. On iOS, the WKURLSchemeHandler protocol is used to handle custom schemes and a hook method is used to bypass limitations. On Android, a setProxy method is called when entering the webview and a revertProxy method is called when exiting.
image

Previously received product requirements needed to support user binding to Steam. Due to well-known reasons, we cannot directly access the Steam Community, so we need to proxy Steam requests within the webview.

iOS#

On iOS, Apple added the WKURLSchemeHandler protocol to WKWebView, which allows adding handling methods for custom schemes. We can proxy requests in the startURLSchemeTask method.

@implementation CustomURLSchemeHandler
-(instancetype)init {
  self.holdUrlSchemeTasks = [[NSMutableDictionary alloc] init];
  return self;
}

- (void)webView:(nonnull WKWebView *)webView startURLSchemeTask:(nonnull id<WKURLSchemeTask>)urlSchemeTask {
  _holdUrlSchemeTasks[urlSchemeTask.description] = @YES;
  NSURLRequest *request = urlSchemeTask.request;
  NSURLSessionConfiguration *configuration = NSURLSessionConfiguration.defaultSessionConfiguration;

    // Set proxy
    NSDictionary *connectionProxyDictionary = @{
      (NSString *)kCFNetworkProxiesHTTPEnable: [NSNumber numberWithInt: 1],
      (NSString *)kCFNetworkProxiesHTTPProxy: self.server,
      (NSString *)kCFNetworkProxiesHTTPPort: self.port,
      @"HTTPSEnable": [NSNumber numberWithInt: 1],
      @"HTTPSProxy": self.server,
      @"HTTPSPort": self.port,
    };
    [configuration setConnectionProxyDictionary:connectionProxyDictionary];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];

    NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
      if(![self->_holdUrlSchemeTasks[urlSchemeTask.description] boolValue]) {
        return;
      }
      if(error) {
        [urlSchemeTask didFailWithError:error];
      } else {
        [urlSchemeTask didReceiveResponse:response];
        [urlSchemeTask didReceiveData:data];
        [urlSchemeTask didFinish];
      }
    }];
  

  [task resume];
}

- (void)webView:(nonnull WKWebView *)webView stopURLSchemeTask:(nonnull id<WKURLSchemeTask>)urlSchemeTask {
  _holdUrlSchemeTasks[urlSchemeTask.description] = @NO;
}

- (void)URLSession:(NSURLSession *)session
              task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)response
        newRequest:(NSURLRequest *)request
 completionHandler:(void (^)(NSURLRequest *))completionHandler
{
  // Handle redirection
  // Requests intercepted by WKURLSchemeHandler do not support URL redirection, need to handle it manually
  completionHandler(nil);
}
@end

However, this protocol can only handle custom schemes, while schemes like https are already handled by default. Therefore, we need to bypass the restriction using a hook method.

@implementation WKWebView (SchemeHandle)

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        SEL originalSelector = @selector(handlesURLScheme:);
        SEL swizzledSelector = @selector(cdz_handlesURLScheme:);
        Method originalMethod = class_getClassMethod(self, originalSelector);
        Method swizzledMethod = class_getClassMethod(self, swizzledSelector);
        method_exchangeImplementations(originalMethod, swizzledMethod);

    });
}

+ (BOOL)cdz_handlesURLScheme:(NSString *)urlScheme {
    if ([urlScheme isEqualToString:@"http"] || [urlScheme isEqualToString:@"https"]) {
        return NO;
    }
    return [self handlesURLScheme:urlScheme];
}

@end

Finally, set the handler in WKWebviewConfiguration

WKWebViewConfiguration *wkWebViewConfig = [WKWebViewConfiguration new];
CustomURLSchemeHandler *handler = [CustomURLSchemeHandler new];
[wkWebViewConfig setURLSchemeHandler:handler forURLScheme:@"https"];
[wkWebViewConfig setURLSchemeHandler:handler forURLScheme:@"http"];

Android#

Android adopts a more compatible way to proxy requests, calling setProxy when entering the webview and revertProxy when exiting.

public class ProxySetting {
  private static final String TAG = "ProxySetting";
  private static final String APPLICATION_NAME = "android.app.Application";

  public static boolean setProxy(WebView webView, String str, int i) {
    if (Build.VERSION.SDK_INT <= 15) {
      return setProxyICS(webView, str, i);
    } else if (Build.VERSION.SDK_INT <= 18) {
      return setProxyJB(webView, str, i);
    } else {
      return setProxyKKPlus(webView, str, i);
    }
  }

  public static boolean revertProxy(WebView webview) {
    if (Build.VERSION.SDK_INT <= 15) {
      return revertProxyICS(webview);
    } else if (Build.VERSION.SDK_INT <= 18) {
      return revertProxyJB(webview);
    } else {
      return revertProxyKKPlus(webview);
    }
  }

  private static boolean setProxyICS(WebView webView, String str, int i) {
    try {
      Class.forName("android.webkit.JWebCoreJavaBridge").getDeclaredMethod("updateProxy", Class.forName("android.net.ProxyProperties")).invoke(getFieldValueSafely(Class.forName("android.webkit.BrowserFrame").getDeclaredField("sJavaBridge"), getFieldValueSafely(Class.forName("android.webkit.WebViewCore").getDeclaredField("mBrowserFrame"), getFieldValueSafely(Class.forName("android.webkit.WebView").getDeclaredField("mWebViewCore"), webView))), Class.forName("android.net.ProxyProperties").getConstructor(String.class, Integer.TYPE, String.class).newInstance(str, Integer.valueOf(i), null));
      return true;
    } catch (Exception unused) {
      return false;
    }
  }

  private static boolean revertProxyICS(WebView webview) {
    try {
      Log.d(TAG, "Setting proxy with 4.0 API.");
      Class jwcjb = Class.forName("android.webkit.JWebCoreJavaBridge");
      Class params[] = new Class[1];
      params[0] = Class.forName("android.net.ProxyProperties");
      Method updateProxyInstance = jwcjb.getDeclaredMethod("updateProxy", params);

      Class wv = Class.forName("android.webkit.WebView");
      Field mWebViewCoreField = wv.getDeclaredField("mWebViewCore");
      Object mWebViewCoreFieldInstance = getFieldValueSafely(mWebViewCoreField, webview);

      Class wvc = Class.forName("android.webkit.WebViewCore");
      Field mBrowserFrameField = wvc.getDeclaredField("mBrowserFrame");
      Object mBrowserFrame = getFieldValueSafely(mBrowserFrameField, mWebViewCoreFieldInstance);

      Class bf = Class.forName("android.webkit.BrowserFrame");
      Field sJavaBridgeField = bf.getDeclaredField("sJavaBridge");
      Object sJavaBridge = getFieldValueSafely(sJavaBridgeField, mBrowserFrame);

      Class ppclass = Class.forName("android.net.ProxyProperties");
      Class pparams[] = new Class[3];
      pparams[0] = String.class;
      pparams[1] = int.class;
      pparams[2] = String.class;
      Constructor ppcont = ppclass.getConstructor(pparams);

      Object o = null;
      updateProxyInstance.invoke(sJavaBridge, o);

      Log.d(TAG, "Setting proxy with 4.0 API successful!");
      return true;
    } catch (Exception ex) {
      Log.e(TAG, "failed to set HTTP proxy: " + ex);
      return false;
    }
  }

  private static boolean setProxyJB(WebView webView, String str, int i) {
    try {
      Object fieldValueSafely = getFieldValueSafely(Class.forName("android.webkit.BrowserFrame").getDeclaredField("sJavaBridge"), getFieldValueSafely(Class.forName("android.webkit.WebViewCore").getDeclaredField("mBrowserFrame"), getFieldValueSafely(Class.forName("android.webkit.WebViewClassic").getDeclaredField("mWebViewCore"), Class.forName("android.webkit.WebViewClassic").getDeclaredMethod("fromWebView", Class.forName("android.webkit.WebView")).invoke(null, webView))));
      Constructor<?> constructor = Class.forName("android.net.ProxyProperties").getConstructor(String.class, Integer.TYPE, String.class);
      Class.forName("android.webkit.JWebCoreJavaBridge").getDeclaredMethod("updateProxy", Class.forName("android.net.ProxyProperties")).invoke(fieldValueSafely, constructor.newInstance(str, Integer.valueOf(i), null));
      return true;
    } catch (Exception unused) {
      return false;
    }
  }

  private static boolean revertProxyJB(WebView webview) {
    Log.d(TAG, "revert proxy with 4.1 - 4.3 API.");
    try {
      Class wvcClass = Class.forName("android.webkit.WebViewClassic");
      Class wvParams[] = new Class[1];
      wvParams[0] = Class.forName("android.webkit.WebView");
      Method fromWebView = wvcClass.getDeclaredMethod("fromWebView", wvParams);
      Object webViewClassic = fromWebView.invoke(null, webview);

      Class wv = Class.forName("android.webkit.WebViewClassic");
      Field mWebViewCoreField = wv.getDeclaredField("mWebViewCore");
      Object mWebViewCoreFieldInstance = getFieldValueSafely(mWebViewCoreField, webViewClassic);

      Class wvc = Class.forName("android.webkit.WebViewCore");
      Field mBrowserFrameField = wvc.getDeclaredField("mBrowserFrame");
      Object mBrowserFrame = getFieldValueSafely(mBrowserFrameField, mWebViewCoreFieldInstance);

      Class bf = Class.forName("android.webkit.BrowserFrame");
      Field sJavaBridgeField = bf.getDeclaredField("sJavaBridge");
      Object sJavaBridge = getFieldValueSafely(sJavaBridgeField, mBrowserFrame);

      Class ppclass = Class.forName("android.net.ProxyProperties");
      Class pparams[] = new Class[3];
      pparams[0] = String.class;
      pparams[1] = int.class;
      pparams[2] = String.class;
      Constructor ppcont = ppclass.getConstructor(pparams);

      Class jwcjb = Class.forName("android.webkit.JWebCoreJavaBridge");
      Class params[] = new Class[1];
      params[0] = Class.forName("android.net.ProxyProperties");
      Method updateProxyInstance = jwcjb.getDeclaredMethod("updateProxy", params);

      Object o = null;
      updateProxyInstance.invoke(sJavaBridge, o);
    } catch (Exception ex) {
      Log.e(TAG, "Setting proxy with >= 4.1 API failed with error: " + ex.getMessage());
      return false;
    }

    Log.d(TAG, "revert proxy with 4.1 - 4.3 API successful!");
    return true;
  }

  private static boolean setProxyKKPlus(WebView webView, String host, int port) {
    Context appContext = webView.getContext().getApplicationContext();
    System.setProperty("http.proxyHost", host);
    System.setProperty("http.proxyPort", port + "");
    System.setProperty("https.proxyHost", host);
    System.setProperty("https.proxyPort", port + "");
    try {
      Field loadedApkField = Class.forName(APPLICATION_NAME).getField("mLoadedApk");
      loadedApkField.setAccessible(true);
      Object loadedApk = loadedApkField.get(appContext);

      Field receiversField = Class.forName("android.app.LoadedApk").getDeclaredField("mReceivers");
      receiversField.setAccessible(true);
      ArrayMap receivers = (ArrayMap) receiversField.get(loadedApk);
      for (Object receiverMap : receivers.values()) {
        for (Object rec : ((ArrayMap) receiverMap).keySet()) {
          Class clazz = rec.getClass();
          if (clazz != null && clazz.getName().contains("ProxyChangeListener")) {
            Method onReceiveMethod = clazz.getDeclaredMethod("onReceive", Context.class, Intent.class);
            Intent intent = new Intent(Proxy.PROXY_CHANGE_ACTION);
            onReceiveMethod.invoke(rec, appContext, intent);
          }
        }
      }
      return true;
    } catch (ClassNotFoundException e) {
      StringWriter stringWriter = new StringWriter();
      e.printStackTrace(new PrintWriter(stringWriter));
      stringWriter.toString();
      return false;
    } catch (NoSuchFieldException e2) {
      StringWriter stringWriter2 = new StringWriter();
      e2.printStackTrace(new PrintWriter(stringWriter2));
      stringWriter2.toString();
      return false;
    } catch (IllegalAccessException e3) {
      StringWriter stringWriter3 = new StringWriter();
      e3.printStackTrace(new PrintWriter(stringWriter3));
      stringWriter3.toString();
      return false;
    } catch (IllegalArgumentException e4) {
      StringWriter stringWriter4 = new StringWriter();
      e4.printStackTrace(new PrintWriter(stringWriter4));
      stringWriter4.toString();
      return false;
    } catch (NoSuchMethodException e5) {
      StringWriter stringWriter5 = new StringWriter();
      e5.printStackTrace(new PrintWriter(stringWriter5));
      stringWriter5.toString();
      return false;
    } catch (InvocationTargetException e6) {
      StringWriter stringWriter6 = new StringWriter();
      e6.printStackTrace(new PrintWriter(stringWriter6));
      stringWriter6.toString();
      return false;
    }
  }

  public static boolean revertProxyKKPlus(WebView webView) {
    Context appContext = webView.getContext().getApplicationContext();
    Properties properties = System.getProperties();
    properties.remove("http.proxyHost");
    properties.remove("http.proxyPort");
    properties.remove("https.proxyHost");
    properties.remove("https.proxyPort");
    try {
      Field loadedApkField = Class.forName(APPLICATION_NAME).getField("mLoadedApk");
      loadedApkField.setAccessible(true);
      Object loadedApk = loadedApkField.get(appContext);
      Field receiversField = Class.forName("android.app.LoadedApk").getDeclaredField("mReceivers");
      receiversField.setAccessible(true);
      ArrayMap receivers = (ArrayMap) receiversField.get(loadedApk);
      for (Object receiverMap : receivers.values()) {
        for (Object rec : ((ArrayMap) receiverMap).keySet()) {
          Class clazz = rec.getClass();
          if (clazz != null && clazz.getName().contains("ProxyChangeListener")) {
            Method onReceiveMethod = clazz.getDeclaredMethod("onReceive", Context.class, Intent.class);
            Intent intent = new Intent(Proxy.PROXY_CHANGE_ACTION);
            onReceiveMethod.invoke(rec, appContext, intent);
          }
        }
      }
      return true;
    } catch (ClassNotFoundException e) {
      StringWriter stringWriter = new StringWriter();
      e.printStackTrace(new PrintWriter(stringWriter));
      stringWriter.toString();
      return false;
    } catch (NoSuchFieldException e2) {
      StringWriter stringWriter2 = new StringWriter();
      e2.printStackTrace(new PrintWriter(stringWriter2));
      stringWriter2.toString();
      return false;
    } catch (IllegalAccessException e3) {
      StringWriter stringWriter3 = new StringWriter();
      e3.printStackTrace(new PrintWriter(stringWriter3));
      stringWriter3.toString();
      return false;
    } catch (IllegalArgumentException e4) {
      StringWriter stringWriter4 = new StringWriter();
      e4.printStackTrace(new PrintWriter(stringWriter4));
      stringWriter4.toString();
      return false;
    } catch (NoSuchMethodException e5) {
      StringWriter stringWriter5 = new StringWriter();
      e5.printStackTrace(new PrintWriter(stringWriter5));
      stringWriter5.toString();
      return false;
    } catch (InvocationTargetException e6) {
      StringWriter stringWriter6 = new StringWriter();
      e6.printStackTrace(new PrintWriter(stringWriter6));
      stringWriter6.toString();
      return false;
    }
  }

  private static Object getFieldValueSafely(Field field, Object obj) throws IllegalArgumentException, IllegalAccessException {
    boolean isAccessible = field.isAccessible();
    field.setAccessible(true);
    Object obj2 = field.get(obj);
    field.setAccessible(isAccessible);
    return obj2;
  }
}
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