Vfrdtyky

I have an Android application (a webbrowser) which uses the default Webview to load webpages. By overloading the shouldInterceptRequest method I'm loading the page with the OkHTTP3 library.

I'm doing that because I want to inject JavaScript into each page before any Javascript is executed. This can't be done with evaluateJavascript because it is asynchronous and therefore there is no guarantee that the code will be executed first. This is the code for it:

override fun shouldInterceptRequest(view: WebView, request: WebResourceRequest): WebResourceResponse? {

    val httpRequestBuilder = Request.Builder()



    when (request.method) {

        "GET" -> httpRequestBuilder.get()

    }



    httpRequestBuilder.url(url)

    httpRequestBuilder.headers(Headers.of(request.requestHeaders))



    val httpRequest = httpRequestBuilder.build()

    val httpResponse = OkHttpClient().newCall(httpRequest).execute()

    httpResponse?.run {

        val contentType = body()?.contentType()

        val mime = contentType?.type() + "/" + contentType?.subtype()

        val encoding = contentType?.charset()?.name() ?: "utf-8"

        val message = if (message().isEmpty()) {

            "OK"

        } else {

            message()

        }

        val header = HashMap<String, String>()

        headers().toMultimap().forEach { entry ->

            header[entry.key] = entry.value[0]

        }

         val contentStream = if (contentType?.subtype() == "html") {

            object : InputStream() {

                val streams = arrayOf(

                    ByteArrayInputStream("<script type="text/javascript">".toByteArray()),

                    context.assets.open("MyJS.js"),

                    ByteArrayInputStream("</script>".toByteArray()),

                    body()?.byteStream()!!

                )

                var currentIndex = 0

                override fun read(): Int {

                    while (currentIndex < streams.size) {

                        val res = streams[currentIndex].read()

                        if (res != -1) {

                            return res

                        }

                        currentIndex++;

                    }

                    return -1;

                }

            }

        } else {

            body()?.byteStream()!!

        }



        return WebResourceResponse(mime, encoding, code(), message, header, contentStream)

}

The injected JavaScript essentially modifies some prototypes. Also it tries to inject itself into frames and iframes on the page to do the same modifications. This is the part of the script which injects itself:

(function() {

    var self = document.currentScript;

    var observer = new window.MutationObserver(function (changes) {

        for (var index = 0; index < changes.length; index++) {

            var change = changes[index];

            if (change.type == "childList") {

                for (var i = 0; i < change.addedNodes.length; i++) {

                    var node = change.addedNodes[i];

                    switch (node.nodeName) {

                        case "IFRAME":

                            var orig_sandbox = node.sandbox;

                            node.sandbox = "allow-scripts";

                            node.contentDocument.write("<script type="text/javascript">" + self.text + "<\/script>");

                            node.sandbox = orig_sandbox;

                            break;

                        case "FRAME":

                            node.contentDocument.write("<script type="text/javascript">" + self.text + "<\/script>");

                    }

                }

            }

        }

    });

    observer.observe(document.documentElement, {childList: true, subtree: true});

})();

The goal is to inject this JavaScript into frames which are not loaded from the network (which would be handled by the shouldInterceptRequest method anyway) but in frames which are not loaded from the network or created by other JavaScript.

Now I have the problem that this doesn't work. It is not injecting into the subframes.

Does anyone know any possibility to inject Javascript into such frames?