how to detect .flv download URL? - javascript

im just interested how firefox plugins like DownloadHelper, is able to automatically find .flv URL

There are a bunch of possible approaches and DownloadHelper seems to implement a couple of them. If you extract the .xpi file (which is a ZIP file) and look in the components folder, you'll see a bunch of different handlers for getting videos. I haven't looked at it thoroughly but you'll notice that dhYoutubeProbe.js basically extracts the video ID from the DOM and then plugs that into a standard YouTube URL pattern for fetching FLVs.
dhNetworkProbe seems to implement a more sneaky and interesting approach - it monitors the browser cache and/or HTTP requests for transfers of media files to get the underlying file's URL.
You could also look at how Firebug or similar monitor HTTP requests and responses. Playing an FLV via Flash player logs to Firebug like any other (non-streaming) request.

Related

Preventing user to see video URL in HTML?

I have an web page where users can view videos.
But the problem is when I inspect the page, it shows the video url.
So is there any idea how we can hide video source like youtube and other videos portal ?
There is no way to hide the video URL entirely without resorting to browser plugins. You can obscure it though, but in most cases they won't be worth it.
Using Media Source Extensions you can deliver segments of video data using obscured urls. And the URL won't be immediately visible in the source of the page. This is similar to what Youtube or Netflix does but requires massive engineering work on the backend. This is also the technique used to play MEPG-DASH with e.g. dash.js or shaka-player.
Set it using Javascript, so it's not viewable with view source, it won't help with inspecting though.
If your issue is people copying the stream URL and using it in their own players, then you might look at protecting it with some sort of tokens security. This is supported by almost any CDN out there, and there are plenty of open source systems to do it in most programming languages.
Lastly, if the issue is that you don't want anyone to copy the content, you can apply DRM protection. One of the easiest and straightforward ways to get started with that, might be using Azure Media Services.

How to extract buffered data from HTML5 <video> element using blob

It has been a long time for people trying to download videos from those sites not allowing them to do, and now they are using the HTML5 element with blob: URL created from MediaSource. Anyway whatever the source is, the video is buffered
and played in the browser so the data must be somewhere.
There are solutions like https://superuser.com/questions/1033563/how-to-download-video-with-blob-url, which is kind of useful for those sites not strictly protected, not working in the extreme case.
So here let's assume that all scripts are strictly obfuscated with network transmission encrypted, and how should we extract the data buffered to be displayed.
Solutions are not limited, except from reimplementing a browser myself.
Edit
The scenario seem like Youtube a lot, but it is impossible to trace anything through the heavily obfuscated script neither the encrypted network transmission.

Javascript - List files being dowloaded by web browser

in the context you access a website, the browser dowload all required files (static files : CSS, scripts) or via AJAX. OK. You can see the dowload process in realtime using the Network tab in your devtools browser.
My question is : is it possible to "listen" to a file being dowloaded using JavaScript as the browser does in the Network tab ?
A concrete example would be to show the user what the browser is being dowloaded in from my website.
While searching over the Internet, I'v seen it's possible to overload xhr native functions : Add a "hook" to all AJAX requests on a page
Nevertheless, I don't think images and CSS download will trigger xhr function because the browser processes in it's own way.
I'm keen to hear the community about it.
Thanks in advance !
If you are explicitly downloading resources in your JavaScript code, you can inject hooks to track the AJAX requests, as per your message above. You can alternatively use the Resource Timing API to track network timing information of your requests, which is nice.
However, it is not possible to see the Network information of resources out of your control, as it requires access to the browser engine.
It is possible to get such information using a Chrome Extension, as an API exists that opens you up to this information. See chrome.devtools.network.

Writing and downloading files clientside crossbrowser

I have a program where the user does some actions (i.e. clicking on several buttons). I want to record their clicks and the buttons that they click to allow the user to then download a text file with a record of their clicks when they click a separate "download" button. I looked at the File-system APIs for HTML 5, but they seemed to not have cross-browser support. I would ideally like to have this entire file generation and download scheme be entirely client-side, but I am open to server-side ideas as well.
TL;DR: Essentially I'm looking for an equivalent to Java's FileWriter, FileReader, ObjectOutputStream, and ObjectInputStream within Vanilla JS or jQuery (would like to stay away from php, but I'll use it as a last option).
Also, why don't all browsers support the filesystem api? (I'm guessing that it would make MSWord and Pages go out of business with all the open source clientside text editors that could come out.)
Unfortunately the HTML5-File-system is no longer a part of the spec, long story short FF refused to implement because they claimed everything you could do in the File-System API was doable in the HTML5 Indexeddb (which was mostly true). Please see this blog post for more on why FF didn't implement. I do not know IE's story. (I may have exagerated why FireFox didn't implement, I'm still bummed because you cannot actually do everything in indexeddb that you can do in the noew "Chrome File-system API")
Typically if two of those three browsers implement a spec, it stays in the spec. Otherwise that spec gets orphaned. However, I'm fairly certain a large reason the file-system api didn't take off is because of the IndexedDB API (caniuse IndexedDB) really took off when both specs were introduced. If you want cross browser support, check this api out.
That all said if you are still set on the file-system api some developers wrote a nice wrapper around the IndexedDB, the File-system api wouldn't actually supply you with a stream anyway. You would have to keep appending events to a given file given a fileWriter object. you'd then have to read the entire file and send to the server via an ajax request and then downloaded from the server once successfully uploaded.
The better route would be to use the IndexedDB apiwhich as stated on developer.mozilla
Open a database.
Create an object store in upgrading database.
Start a transaction and make a request to do some database operation, like adding or retrieving data.
Wait for the operation to complete by listening to the right kind of DOM event.
Do something
with the results (which can be found on the request object).
Here are a couple tutorials on the IndexedDB.
https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API/Using_IndexedDB
http://www.html5rocks.com/en/tutorials/indexeddb/todo/
As for giving the user that file, as mentioned briefly before you would have to upload the file to the server and download upon the "download" request. Unfortunately you have to trick the user into giving them the data already on their machine. Anyway, hope this all helps.

How can a Chrome extension save many files to a user-specified directory?

I'm working on a Chrome extension to be used as an internal tool. Its required behavior is:
As a page action, enable an address bar icon when looking at certain intranet pages.
when the user clicks the icon, identify all files of a certain media type (say, .jpg) on the page, and
silently save them all to a directory on the user's local drive.
This question has been asked before, but the answer then was "use NPAPI", and NPAPI is now derelict.
So, what is the currently available way to achieve this? The ones I've looked at are:
The chrome.FileSystem API --- but this does not save files in any user-accessible location. Instead the stored files are hidden behind obfuscated names in an undocumented directory. User requires that the files be stored under their original names in an accessible directory.
The HTML5 download attribute, by creating a data: URL and programmatically clicking it. This pops up a "save as..." dialog for each file, which is unacceptable when there are a hundred assets on a single page. User requires that the files be downloaded without further interaction beyond the single icon click.
The Chrome Download API, but that is only available in the beta and dev channels. User requires this extension work with mainstream Chrome.
Use the Native Messaging API by creating a small .exe that simply saves a file to disk, and then pass the .jpg as a blob to it. This seems very cumbersome and I am not even sure how to reliably pass large blobs to EXEs like that.
Is there another approach I can try?
You've done quite a lot of research. Indeed, regular web pages cannot write to the user's filesystem without any plugins or extensions. Also, the HTML5 Filesystem API only provides access to a virtual filesystem, as you've observed.
However, you are confusing the chrome.fileSystem API with the HTML5 FileSystem API. Unlike the HTML FileSystem API, Chrome's fileSystem (app) API can directly write to the user's filesystem (e.g. ~/Documents or %USERPROFILE%\Documents), specified by the user.
This API is only available to Chrome apps, not extensions. This is not a problem, especially since you're developing an internal tool, because you can install the app and extension, and use message passing to communicate between the extension (page action) and app (file system access) (example).
About chrome.downloads: Since your extension is internal, you can probably force users to get on the beta/dev channel in order to use this API. The only limitation of this API is that the files will be saved in (a subdirectory of) the user-defined Downloads folder.
EDIT: The chrome.downloads API is now avaiable in all channels, including the stable branch (since Chrome 31).
I am afraid that you have done your homework, meaning you looked at all possible alternatives.
The best way to achieve exactly what you want, would be (as you mentioned) using a supporting native app and communicating through Native Messaging. BTW, since bandwidth is rarely a problem on intranets, you might find it simpler to pass the resources (e.g. images) URLs and have the app download and save them.
(Yes, it will be more cumbersome than simply developing an extension, but one's got to do what they've got to do, right ?)
On the other hand, if you are willing to sacrifice a little bit of user's experience over simplicity of development, I suggest combining the HTML5 goodies (that allow you to create and download a file locally) with a JS zipping library (e.g. JSZip), so the user only has to download a single zip file (and is only prompted once). BTW, if the user wishes, he/she can choose to always download the files without prompting (but you knew that already).
Use the Native Messaging App idea.
The native app is cumbersome and a pain to write because documentation is poor, and unless you get the JSON formatting exactly correct on both ends you will not see anything in a console because stdin and stdout are taken over.
But, you will be happier when it is done because you can use standard tools (e.g., Windows Explorer, a hex editor, TeamViewer...) to view, move, and delete files, and otherwise see what is going on. Chrome's sand-boxed file system works, but seems to now be a dead-end (no other browsers have picked it up). No one is likely to develop third-party tools for it. Of course you probably don't need tools once everything is working, but until then, debugging is a nightmare because you need to write code (and quite a lot of code) just to track what files are in what directories, file versions, remaining disk space...
Another solution for internal (or may be non-internal) usage is to connect to a websocket server, local or remote.
You can put it in both background.js or content.js (use wss:// for https://)
var ws = new WebSocket('ws://echo.websocket.org');
// var ws = new WebSocket('ws://127.0.0.1:9000');
ws.onmessage = function(res) {
console.log('received data:', res.data);
};
ws.onopen = function() {
ws.send('hello');
};

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