feat(ios): add http(s) proxy/scheme

This adds a new URLSchemeHandler which can proxy http(s) requests to external servers.
This is useful for some CORS issues and webview bugs that affect the use of cookies in CORS requests via XHR and fetch.
For that reason cookies will be synced between proxied requests on the native layer and the webview.

Author: NiklasMerz

src/ios/IONAssetHandler.h

@@ -5,6 +5,7 @@
 
 @property (nonatomic, strong) NSString * basePath;
 @property (nonatomic, strong) NSString * scheme;
+@property (nonatomic) Boolean isRunning;
 
 -(void)setAssetPath:(NSString *)assetPath;
 - (instancetype)initWithBasePath:(NSString *)basePath andScheme:(NSString *)scheme;

src/ios/IONAssetHandler.m

@@ -19,14 +19,72 @@ - (instancetype)initWithBasePath:(NSString *)basePath andScheme:(NSString *)sche
 
 - (void)webView:(WKWebView *)webView startURLSchemeTask:(id <WKURLSchemeTask>)urlSchemeTask
 {
+    self.isRunning = true;
+    Boolean loadFile = true;
     NSString * startPath = @"";
     NSURL * url = urlSchemeTask.request.URL;
-    NSString * stringToLoad = url.path;
+    NSDictionary * header = urlSchemeTask.request.allHTTPHeaderFields;
+    NSMutableString * stringToLoad = [NSMutableString string];
+    [stringToLoad appendString:url.path];
     NSString * scheme = url.scheme;
+    NSString * method = urlSchemeTask.request.HTTPMethod;
+    NSData * body = urlSchemeTask.request.HTTPBody;
+    NSData * data;
+    NSInteger statusCode;
 
     if ([scheme isEqualToString:self.scheme]) {
         if ([stringToLoad hasPrefix:@"/_app_file_"]) {
             startPath = [stringToLoad stringByReplacingOccurrencesOfString:@"/_app_file_" withString:@""];
+        } else if ([stringToLoad hasPrefix:@"/_http_proxy_"]||[stringToLoad hasPrefix:@"/_https_proxy_"]) {
+            if(url.query) {
+                [stringToLoad appendString:@"?"];
+                [stringToLoad appendString:url.query];
+            }
+            loadFile = false;
+            startPath = [stringToLoad stringByReplacingOccurrencesOfString:@"/_http_proxy_" withString:@"http://"];
+            startPath = [startPath stringByReplacingOccurrencesOfString:@"/_https_proxy_" withString:@"https://"];
+            NSURL * requestUrl = [NSURL URLWithString:startPath];
+            WKWebsiteDataStore* dataStore = [WKWebsiteDataStore defaultDataStore];
+            WKHTTPCookieStore* cookieStore = dataStore.httpCookieStore;
+            NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
+            [request setHTTPMethod:method];
+            [request setURL:requestUrl];
+            if (body) {
+                [request setHTTPBody:body];
+            }
+            [request setAllHTTPHeaderFields:header];
+            [request setHTTPShouldHandleCookies:YES];
+            
+            [[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
+                if(error) {
+                    NSLog(@"Proxy error: %@", error);
+                }
+                
+                // set cookies to WKWebView
+                NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)response;
+                if(httpResponse) {
+                    NSArray* cookies = [NSHTTPCookie cookiesWithResponseHeaderFields:[httpResponse allHeaderFields] forURL:response.URL];
+                    [[NSHTTPCookieStorage sharedHTTPCookieStorage] setCookies:cookies forURL:httpResponse.URL mainDocumentURL:nil];
+                    cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies];
+                    
+                    for (NSHTTPCookie* c in cookies)
+                    {
+                        dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
+                            //running in background thread is necessary because setCookie otherwise fails
+                            dispatch_async(dispatch_get_main_queue(), ^(void){
+                                [cookieStore setCookie:c completionHandler:nil];
+                            });
+                        });
+                    };
+                }
+
+                // Do not use urlSchemeTask if it has been closed in stopURLSchemeTask
+                if(self.isRunning) {
+                    [urlSchemeTask didReceiveResponse:response];
+                    [urlSchemeTask didReceiveData:data];
+                    [urlSchemeTask didFinish];
+                }
+            }] resume];
         } else {
             startPath = self.basePath;
             if ([stringToLoad isEqualToString:@""] || [url.pathExtension isEqualToString:@""]) {
@@ -37,29 +95,31 @@ - (void)webView:(WKWebView *)webView startURLSchemeTask:(id <WKURLSchemeTask>)ur
         }
     }
 
-    NSData * data = [[NSData alloc] initWithContentsOfFile:startPath];
-    NSInteger statusCode = 200;
-    if (!data) {
-        statusCode = 404;
-    }
-    NSURL * localUrl = [NSURL URLWithString:url.absoluteString];
-    NSString * mimeType = [self getMimeType:url.pathExtension];
-    id response = nil;
-    if (data && [self isMediaExtension:url.pathExtension]) {
-        response = [[NSURLResponse alloc] initWithURL:localUrl MIMEType:mimeType expectedContentLength:data.length textEncodingName:nil];
-    } else {
-        NSDictionary * headers = @{ @"Content-Type" : mimeType, @"Cache-Control": @"no-cache"};
-        response = [[NSHTTPURLResponse alloc] initWithURL:localUrl statusCode:statusCode HTTPVersion:nil headerFields:headers];
+    if(loadFile) {
+        data = [[NSData alloc] initWithContentsOfFile:startPath];
+        statusCode = 200;
+        if (!data) {
+            statusCode = 404;
+        }
+        NSURL * localUrl = [NSURL URLWithString:url.absoluteString];
+        NSString * mimeType = [self getMimeType:url.pathExtension];
+        id response = nil;
+        if (data && [self isMediaExtension:url.pathExtension]) {
+            response = [[NSURLResponse alloc] initWithURL:localUrl MIMEType:mimeType expectedContentLength:data.length textEncodingName:nil];
+        } else {
+            NSDictionary * headers = @{ @"Content-Type" : mimeType, @"Cache-Control": @"no-cache"};
+            response = [[NSHTTPURLResponse alloc] initWithURL:localUrl statusCode:statusCode HTTPVersion:nil headerFields:headers];
+        }
+        
+        [urlSchemeTask didReceiveResponse:response];
+        [urlSchemeTask didReceiveData:data];
+        [urlSchemeTask didFinish];
     }
-    
-    [urlSchemeTask didReceiveResponse:response];
-    [urlSchemeTask didReceiveData:data];
-    [urlSchemeTask didFinish];
-
 }
 
 - (void)webView:(nonnull WKWebView *)webView stopURLSchemeTask:(nonnull id<WKURLSchemeTask>)urlSchemeTask
 {
+    self.isRunning = false;
     NSLog(@"stop");
 }
 

src/www/util.js

@@ -11,6 +11,12 @@ var WebView = {
     if (url.startsWith('file://')) {
       return window.WEBVIEW_SERVER_URL + url.replace('file://', '/_app_file_');
     }
+    if (url.startsWith('http://')) {
+      return window.WEBVIEW_SERVER_URL + url.replace('http://', '/_http_proxy_');
+    }
+    if (url.startsWith('https://')) {
+      return window.WEBVIEW_SERVER_URL + url.replace('https://', '/_https_proxy_');
+    }
     if (url.startsWith('content://')) {
       return window.WEBVIEW_SERVER_URL + url.replace('content:/', '/_app_content_');
     }