How can I disable "Save Video As..." from a browser's right-click menu to prevent clients from downloading a video?
Are there more complete solutions that prevent the client from accessing a file path directly?
You can't.
That's because that's what browsers were designed to do: Serve content. But you can make it harder to download.
Convenient "Solution"
I'd just upload my video to a third-party video site, like YouTube or Vimeo. They have good video management tools, optimizes playback to the device, and they make efforts in preventing their videos from being ripped with zero effort on your end.
Workaround 1, Disabling "The Right Click"
You could disable the contextmenu event, aka "the right click". That would prevent your regular skiddie from blatantly ripping your video by right clicking and Save As. But then they could just disable JS and get around this or find the video source via the browser's debugger. Plus this is bad UX. There are lots of legitimate things in a context menu than just Save As.
Workaround 2, Video Player Libraries
Use custom video player libraries. Most of them implement video players that customize the context menu to your liking. So you don't get the default browser context menu. And if ever they do serve a menu item similar to Save As, you can disable it. But again, this is a JS workaround. Weaknesses are similar to Workaround 1.
Workaround 3, HTTP Live Streaming
Another way to do it is to serve the video using HTTP Live Streaming. What it essentially does is chop up the video into chunks and serve it one after the other. This is how most streaming sites serve video. So even if you manage to Save As, you only save a chunk, not the whole video. It would take a bit more effort to gather all the chunks and stitch them using some dedicated software.
Workaround 4, Painting on Canvas
Another technique is to paint <video> on <canvas>. In this technique, with a bit of JavaScript, what you see on the page is a <canvas> element rendering frames from a hidden <video>. And because it's a <canvas>, the context menu will use an <img>'s menu, not a <video>'s. You'll get a Save Image As instead of a Save Video As.
Workaround 5, CSRF Tokens
You could also use CSRF tokens to your advantage. You'd have your sever send down a token on the page. You then use that token to fetch your video. Your server checks to see if it's a valid token before it serves the video, or get an HTTP 401. The idea is that you can only ever get a video by having a token which you can only ever get if you came from the page, not directly visiting the video url.
This is a simple solution for those wishing to simply remove the right-click "save" option from the html5 videos
$(document).ready(function(){
$('#videoElementID').bind('contextmenu',function() { return false; });
});
Yes, you can do this in three steps:
Place the files you want to protect in a subdirectory of the directory where your code is running.
www.foo.com/player.html www.foo.com/videos/video.mp4
Save a file in that subdirectory named ".htaccess" and add the lines below.
www.foo.com/videos/.htaccess
#Contents of .htaccess
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^http://foo.com/.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www.foo.com/.*$ [NC]
RewriteRule .(mp4|mp3|avi)$ - [F]
Now the source link is useless, but we still need to make sure any user attempting to download the file cannot be directly served the file.
For a more complete solution, now serve the video with a flash player (or html canvas) and never link to the video directly. To just remove the right click menu, add to your HTML:
<body oncontextmenu="return false;">
The Result:
www.foo.com/player.html will correctly play video, but if you visit www.foo.com/videos/video.mp4:
Error Code 403: FORBIDDEN
This will work for direct download, cURL, hotlinking, you name it.
This is a complete answer to the two questions asked and not an answer to the question: "can I stop a user from downloading a video they have already downloaded."
Simple answer,
YOU CAN'T
If they are watching your video, they have it already
You can slow them down but can't stop them.
The best way that I usually use is very simple, I fully disable context menu in the whole page, pure html+javascript:
<body oncontextmenu="return false;">
That's it! I do that because you can always see the source by right click.
Ok, you say: "I can use directly the browser view source" and it's true but we start from the fact that you CAN'T stop downloading html5 videos.
As a client-side developer I recommend to use blob URL,
blob URL is a client-side URL which refers to a binary object
<video id="id" width="320" height="240" type='video/mp4' controls > </video>
in HTML leave your video src blank,
and in JS fetch the video file using AJAX, make sure the response type is blob
window.onload = function() {
var xhr = new XMLHttpRequest();
xhr.open('GET', 'mov_bbb.mp4', true);
xhr.responseType = 'blob'; //important
xhr.onload = function(e) {
if (this.status == 200) {
console.log("loaded");
var blob = this.response;
var video = document.getElementById('id');
video.oncanplaythrough = function() {
console.log("Can play through video without stopping");
URL.revokeObjectURL(this.src);
};
video.src = URL.createObjectURL(blob);
video.load();
}
};
xhr.send();
}
Note: This method is not recommended for large file
EDIT
Use cross-origin blocking and header token checking to prevent direct downloading.
If the video is delivered via an API; Use a different http method (PUT / POST) instead of 'GET'
PHP sends the html5 video tag together with a session where the key is a random string and the value is the filename.
ini_set('session.use_cookies',1);
session_start();
$ogv=uniqid();
$_SESSION[$ogv]='myVideo.ogv';
$webm=uniqid();
$_SESSION[$webm]='myVideo.webm';
echo '<video autoplay="autoplay">'
.'<source src="video.php?video='.$ogv.' type="video/ogg">'
.'<source src="video.php?video='.$webm.' type="video/webm">'
.'</video>';
Now PHP is asked to send the video. PHP recovers the filename; deletes the session and sends the video instantly. Additionally all the 'no cache' and mime-type headers must be present.
ini_set('session.use_cookies',1);
session_start();
$file='myhiddenvideos/'.$_SESSION[$_GET['video']];
$_SESSION=array();
$params = session_get_cookie_params();
setcookie(session_name(),'', time()-42000,$params["path"],$params["domain"],
$params["secure"], $params["httponly"]);
if(!file_exists($file) or $file==='' or !is_readable($file)){
header('HTTP/1.1 404 File not found',true);
exit;
}
readfile($file);
exit:
Now if the user copy the url in a new tab or use the context menu he will have no luck.
We could make that not so easy by hiding context menu, like this:
<video oncontextmenu="return false;" controls>
<source src="https://yoursite.com/yourvideo.mp4" >
</video>
You can use
<video src="..." ... controlsList="nodownload">
https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/controlsList
It doesn't prevent saving the video, but it does remove the download button and the "Save as" option in the context menu.
We ended up using AWS CloudFront with expiring URLs. The video will load, but by the time the user right clicks and chooses Save As the video url they initially received has expired. Do a search for CloudFront Origin Access Identity.
Producing the video url requires a key pair which can be created in the AWS CLI. FYI this is not my code but it works great!
$resource = 'http://cdn.yourwebsite.com/videos/yourvideourl.mp4';
$timeout = 4;
//This comes from key pair you generated for cloudfront
$keyPairId = "AKAJSDHFKASWERASDF";
$expires = time() + $timeout; //Time out in seconds
$json = '{"Statement":[{"Resource":"'.$resource.'","Condition" {"DateLessThan":{"AWS:EpochTime":'.$expires.'}}}]}';
//Read Cloudfront Private Key Pair
$fp=fopen("/absolute/path/to/your/cloudfront_privatekey.pem","r");
$priv_key=fread($fp,8192);
fclose($fp);
//Create the private key
$key = openssl_get_privatekey($priv_key);
if(!$key)
{
echo "<p>Failed to load private key!</p>";
return;
}
//Sign the policy with the private key
if(!openssl_sign($json, $signed_policy, $key, OPENSSL_ALGO_SHA1))
{
echo '<p>Failed to sign policy: '.openssl_error_string().'</p>';
return;
}
//Create url safe signed policy
$base64_signed_policy = base64_encode($signed_policy);
$signature = str_replace(array('+','=','/'), array('-','_','~'), $base64_signed_policy);
//Construct the URL
$url = $resource.'?Expires='.$expires.'&Signature='.$signature.'&Key-Pair-Id='.$keyPairId;
return '<div class="videowrapper" ><video autoplay controls style="width:100%!important;height:auto!important;"><source src="'.$url.'" type="video/mp4">Your browser does not support the video tag.</video></div>';
You can at least stop the the non-tech savvy people from using the right-click context menu to download your video. You can disable the context menu for any element using the oncontextmenu attribute.
oncontextmenu="return false;"
This works for the body element (whole page) or just a single video using it inside the video tag.
<video oncontextmenu="return false;" controls>...</video>
First of all realise it is impossible to completely prevent a video being downloaded, all you can do is make it more difficult. I.e. you hide the source of the video.
A web browser temporarily downloads the video in a buffer, so if could prevent download you would also be preventing the video being viewed as well.
You should also know that <1% of the total population of the world will be able to understand the source code making it rather safe anyway. That does not mean you should not hide it in the source as well - you should.
You should not disable right click, and even less you should display a message saying "You cannot save this video for copyright reasons. Sorry about that.". As suggested in this answer.
This can be very annoying and confusing for the user. Apart from that; if they disable JavaScript on their browser they will be able to right click and save anyway.
Here is a CSS trick you could use:
video {
pointer-events: none;
}
CSS cannot be turned off in browser, protecting your video without actually disabling right click. However one problem is that controls cannot be enabled either, in other words they must be set to false. If you are going to inplament your own Play/Pause function or use an API that has buttons separate to the video tag then this is a feasible option.
controls also has a download button so using it is not such a good idea either.
Here is a JSFiddle example.
If you are going to disable right click using JavaScript then also store the source of the video in JavaScript as well. That way if the user disables JavaScript (allowing right click) the video will not load (it also hides the video source a little better).
From TxRegex answer:
<video oncontextmenu="return false;" controls>
<source type="video/mp4" id="video">
</video>
Now add the video via JavaScript:
document.getElementById("video").src = "https://www.w3schools.com/html/mov_bbb.mp4";
Functional JSFiddle
Another way to prevent right click involves using the embed tag. This is does not however provide the controls to run the video so they would need to be inplamented in JavaScript:
<embed src="https://www.w3schools.com/html/mov_bbb.mp4"></embed>
well, you can't protect it 100% but you can make it harder. these methods that I'm explaining, I faced them during studying protection methods in PluralSight and BestDotNetTraining. nevertheless, none of these methods stopped me from downloading what I want, but I had a hard time to curate the downloader to pass their protection.
In addition to other mentioned methods to disable the context menu. the user still is able to use third-party tools like InternetDownload manager or other similar software to download the videos. the protection method that I'm explaining here is to mitigate those 3rd party software.
the requirement of all of these methods is to block a user when you identify someone is downloading your videos. in this way they are able to download only one or two videos only before you banned them from accessing to your website.
disclaimer
I will not accept any responsibility if someone abuses these methods or use it to harm others or the websites that I mentioned as an example. it's just for sharing knowledge to help you to protect your intellectual product.
generate links with an expiry
the requirement for this is to create a download link per user. that one can easily be handled by azure blob storage or amazon s3. you can create a download link with twice of the video length expiry timestamp. then you need to capture that video link and the time that is requested. this is necessary for the next method. the catch for this method is you are generating the download link when the user click the play button.
on play button event you will send a request to the server and get the link and update the source.
throttle the video request rate
then you monitor how fast the user request for the second video. if the user request for a download link too fast, then you block them right away. you can't put this threshold too big because you can mistakenly block users that are just browsing or skimming through the videos.
Enable HTTP Range
use some js library like videojs to play your video, also you need to return an AcceptRange in your header. Azure blob storage supports this out of the box. this way the browser starts to download the video chunk by chunk. usually, 32byte by 32byte. then you need to listen to videojs timeupdate change and update your server about the percentage that the video is watched. the percentage that the video is watched can't be more than the percentage that video is delivered. and if you are delivering a video content without receiving any percentage change, then you can block the user. because for sure they are downloading.
implementing this is tricky because the user can skip the video forward or backwards so be conscious about this when you are implementing this.
this is how BestDotnetTraining is handling the timeupdate
myPlayer.ready(function () {
//var player = this;
this.src({
type: "video/mp4",
src: videoURL
});
if (videoId) {
myPlayer.play();
this.on('timeupdate', function () {
var currentPercent = parseInt(100 * myPlayer.currentTime() / myPlayer.duration());//calcualte as percentage
if (currentPercent % 5 == 0) {
//send percentage to server
SaveVideoDurationWatched(currentPercent, videoId);
}
});
}
});
anyway, the user is able to work around this by using some download method that downloads a file through streaming. almost c# do it out of the box and for nodejs, you can use request module. then you need to start a stopWatch, listen to a package received and compare the total byte received compare to the total size. this way you can calculate a percentage and the time spent to get that amount of percentage. then use the Thread.Sleep() or something like that to delay the thread the amount that you have to wait if you watch the video normally. also before the sleep the user can call the server and update the percentage that is received. so the server thinks that the user is actually watching a video.
the calculation will be something like this, for example, if you calculate that you received 1 per cent so far, then you can calculate the amount that you should wait to sleep the download thread. in this way you can't download a video faster than what it's actual length is. if a video is 24 min. it will takes 24 min to download it. (plus the threshold we put in the first method)
original video length 24 minute
24 min *60000 = 1,440,000 miliseconds
1,440,000 % 100 = 14,400 milisecond is needed to download one percent
check the browser agent
when you are serving a webpage and serving the video link or accepting the progress update request you can look at the browser agent. if it's different then ban the user.
just be aware that some old browser doesn't pass this information. so you should ignore this when there is no browser agent in both video request and webpage request. but if one request has it and another one doesn't, then you should ban the user.
to work around this the user can set the browser agent header manually same as the headless browser that they are using to capture the download link.
check the referer header
when the referer is something other than your host URL or the page URL that you are serving the video, you can ban the user, because they put the download link in another tab or another application. even you can do that for the progress update request.
the requirement for this is to has a mapping of video and the page that shows that video. you can create some convention or pattern to understand what the URL should be, it's up to your design.
to work around it the user can set the referrer header manually equal to the download page URL when downloading the videos.
Calculate the time between request
if you receive so many requests that the time between them is the same, then you should block the user. you should put this to capture how much is time between the video link generation request. if they are the same (plus/minus some threshold) and it happens more than a number of times, then you can ban the user. because if there is a bot that is going to crawl your website or videos, then usually they have the same sleep time between their request. so if you receive each request, for example, every 1.3(plus/mins some deviation) minutes. then you raise an alarm. for this, you can use some statistic calculation to know the deviation between the requests.
to workaround this, the user can put a random sleep time between the requests.
sample code
I have a repo PluralSight-Downloader that is doing it halfway. I created this repo almost 5 years ago. because I wrote it for study purpose and own personal use only, the repo isn't received any update so far and I'm not going to update or make it easy to work with. it's just an example of how it can be done.
The
<body oncontextmenu="return false;">
no longer works. Chrome and Opera as of June 2018 has a submenu on the timeline to allow straight download, so user doesn't need to right click to download that video. Interestingly Firefox and Edge don't have this ...
Using a service such as Vimeo: Sign in Vimeo > Goto Video > Settings > Privacy > Mark as Secured, and also select embed domains. Once the embed domains are set, it will not allow anyone to embed the video or display it from the browser unless connecting from the domains specified. So, if you have a page that is secured on your server which loads the Vimeo player in iframe, this makes it pretty difficult to get around.
+1 simple and cross-browser way:
You can also put transparent picture over the video with css z-index and opacity.
So users will see "save picture as" instead of "save video" in context menu.
Here's what I did:
function noRightClick() {
alert("You cannot save this video for copyright reasons. Sorry about that.");
}
<body oncontextmenu="noRightClick();">
<video>
<source src="http://calumchilds.com/videos/big_buck_bunny.mp4" type="video/mp4">
</video>
</body>
This also works for images, text and pretty much anything. However, you can still access the "Inspect" and the "View source" tool through keyboard shortcuts. (As the answer at the top says, you can't stop it entirely.) But you can try to put barriers up to stop them.
Here's a complete solution for disabling download including right click > Save as... in the context menu:
<video oncontextmenu="return false;" controlsList="nodownload">
</video>
Short Answer: Encrypt the link like youtube does, don't know how than ask youtube/google of how they do it. (Just in case you want to get straight into the point.)
I would like to point out to anyone that this is possible because youtube does it and if they can so can any other website and it isn't from the browser either because I tested it on a couple browsers such as microsoft edge and internet explorer and so there is a way to disable it and seen that people still say it...I tries looking for an answer because if youtube can than there has to be a way and the only way to see how they do it is if someone looked into the scripts of youtube which I am doing now. I also checked to see if it was a custom context menu as well and it isn't because the context menu is over flowing the inspect element and I mean like it is over it and I looked and it never creates a new class and also it is impossible to actually access inspect element with javascript so it can't be. You can tell when it double right-click a youtube video that it pops up the context menu for chrome. Besides...youtube wouldn't add that function in. I am doing research and looking through the source of youtube so I will be back if I find the answer...if anyone says you can't than, well they didn't do research like I have. The only way to download youtube videos is through a video download.
Okay...I did research and my research stays that you can disable it except there is no javascript to it...you have to be able to encrypt the links to the video for you to be able to disable it because I think any browser won't show it if it can't find it and when I opened a youtube video link it showed as this "blob:https://www.youtube.com/e5c4808e-297e-451f-80da-3e838caa1275" without quotes so it is encrypting it so it cannot be saved...you need to know php for that but like the answer you picked out of making it harder, youtube makes it the hardest of heavy encrypting it, you need to be an advance php programmer but if you don't know that than take the person you picked as best answer of making it hard to download it...but if you know php than heavy encrypt the video link so it only is able to be read on yours...I don't know how to explain how they do it but they did and there is a way. The way youtube Encrypts there videos is quite smart so if you want to know how to than just ask youtube/google of how they do it...hope this helps for you although you already picked a best answer. So encrypting the link is best in short terms.
controlsList Prevent action such as download begin fullscreen without adding any other JavaScript function
<video width="400" controlsList="nofullscreen nodownload" controls>
Try this for disable download Video options
<video src="" controls controlsList="nodownload"></video>
It seems like streaming the video through websocket is a viable option, as in stream the frames and draw them on a canvas sort of thing.
Video streaming over websockets using JavaScript
I think that would provide another level of protection making it more difficult for the client to acquire the video and of course solve your problem with "Save video as..." right-click context menu option ( overkill ?! ).
If you are looking for a complete solution/plugin, I've found this very useful
https://github.com/mediaelement/mediaelement
Prevent HTML5 video from being downloaded (right-click saved)
<video type="video/mp4" width="330" height="300" controlsList="nodownload" oncontextmenu="return false;" controls></video>
You can't.
For example, people can use some APIfor example desktopCapture, getUserMedia that
allows users to record screen, window, tab.
People can use it and write it to the canvas and then concatenate all the chunks together to get the video,
So there is no way to stop them from downloading the video if they really want it.
I found a good answer to a similar problem, using PHP instead of JavaScript for better security.
I want to play test.mp4 in the user's browser using the browser's default player (just as though URL/test.mp4 had been clicked on a Web page), but requiring a password, which is either supplied by the user or internally by software.
Here is a brief sketch of the idea. It starts with the user going to (running) a program I wrote called secure.php to play test.mp4.
The file test.mp4 is in a subdirectory ("secureSubdirectory") that contains a .htaccess containing "Require all denied". This immediately prevents any direct access through a URL.
When secure.php is run, it supplies a password (or queries the user for a password), then does a POST to itself that includes the password, verifies it using a salt, using the PHP commands:
$Hash=base64_encode(hash_hmac("sha256",$Pwd,$Salt,true));
$HashesAreSame=hash_equals($Hash,$GoalHash);
then tests for test.mp4 existing, and executes the following PHP code to return the test.mp4 file as a byte stream to the user's browser:
header("Content-Type: video/mp4");
echo file_get_contents("secureSubdirectory/$path");
exit;
The video shows as expected. If I then right-click on the page showing the video and try saving the video, the resulting file will just contain an error string, like "Error: password not found", since test.mp4 is being queried using the plain secure.php URL, not through POST with the correct password.
Of course, you can obtain the response payload (the video bytes) using the Network option of the browser debugging tools, but this could be prevented by the PHP program or the .htaccess file if the browser provided an option to prevent access to the debugging tools.
I can't imagine a failure case, but I'd be very interested if one exists, as simple but perfect authorization is a very rare thing. (Note that, since this method relies on a password, associating it with the user is not a secure way to authenticate, since the user can accidentally or deliberately publish or share the password.)
#Clayton-Graul had what I was looking for, except I needed the CoffeeScript version for a site using AngularJS. Just in case you need that too, here's what you put in the AngularJS controller in question:
# This is how to we do JQuery ready() dom stuff
$ ->
# let's hide those annoying download video options.
# of course anyone who knows how can still download
# the video, but hey... more power to 'em.
$('#my-video').bind 'contextmenu', ->
false
"strange things are afoot at the circle k" (it's true)
Everything you see in the browser is downloaded content. The question being alluded to is how to save that content in the browser. To view content, client browsers download from content servers and make it available locally.
One solution becoming popular is to save (ephemeral) content in browser only, and for a limited time, in a way that cannot be saved directly. Blobs are one implementation of this with the added benefit of reducing bandwidth & storage overheads, since the content is stored in binary objects.
The short expiry of content makes persistent storage almost impossible to ordinary users since new content is displayed before user can attempt to save expired content.
Related
I am new to php. I am having anchor links each will play a video in new tab after clicking on it.
So the problem is: If anyone knows the exact url of video, they can paste that url in browser and can watch the video, which should not happen. But currently this is the issue I am having.
I knew that we can do this by checking with sessions, but not understanding in a programmatic approach. I tried in other way using html5 video links too, but has no luck that way either.
Kindly provide me some great solution for my above issue.
Below are the video anchor links :
MyVideo1
MyVideo2
MyVideo3
Some time ago I programmed a webpage which can stream videos for logged in users. I didn't made a direct link reference to the video file, I put the video files in a private directory not accessible via browser which is readable by the PHP files. Then the links to the video files were all looking like this: <a href='stream.php?id=[id]'>Video</a> where the id is a randomly generated string which is saved and valid for a limited time. So when someone has this link to the stream.php script he cannot use it as the id will be invalid at a later time. And the php script just takes the mp4 file out of the private directory and puts it to output. It's also possible to make the stream.php script able to handle jumps during watching the video.
Is it possible to put PHP code into raw images?
For example:
http://gifsec.com/wp-content/uploads/GIF/2014/05/GIF-When-white-guys-dance.gif
If you go to that url you'll just see the raw image on a white page. Is it possible to somehow put code into this raw page? For example, you may want to put Google analytics tracking into raw image files so you can track people on reddit sharing raw files.
Not that I know of, what you may want to consider is having people share the link to that file so they can download it and then put code into the page that link redirects to that tracks or counts visitors. Tracking the visitor is harder and leads into ethical issues, so I would just set up google analytics and put their code into that page.
No,
http://gifsec.com/wp-content/uploads/GIF/2014/05/GIF-When-white-guys-dance.gif
is a resource on your server. that URL simply directs the browser to where the image is stored on the server.
to achieve what you want. simply create a page and include the image into
http://gifsec.com/GIF-When-white-guys-dance
<img src=''> on this page you can then add your Google analytic code.
Images are transferred from server to browser with binary encoding. this is why it will not work how you are thinking
You can hide anything you want in an image file. This is called steganography. The problem is that the code won't be executed unless it's uploaded to a server that is specifically set up to extract and run it.
It's not silly, just difficult. What you would have to do is use a PHP script to process it back. As such, your dance.gif would become dance.php and you would link to that. It will add some overhead to your server to do this so just be aware, however, this would allow you to track it via PHP. You could then import that data into Google Analytics at a later date.
Here's some pseudo code (we'll call this dance.php)
<?php
//Insert some tracking here, like a Database INSERT statement
$img = imagecreatefromgif('/path/to/dance.gif');
header('Content-Type: image/gif');
imagegif($image);
imagedestroy($image);
Then in your HTML
<img src="dance.php">
What you need is called pixel tracking also called web bug.
Take a look at this answer:
https://stackoverflow.com/a/13079838/797495
Now, I am encountering some difficulties when I have to scan or crawl a video URL link. This web page is using the Flash-based technology to embed the video and stream video.
In order to understand more clearly, this is a link example:
http://vnexpress.net/gl/the-gioi/tu-lieu/2012/11/bai-phat-bieu-thua-nhan-that-bai-cua-romney/
The above link has below content (HTML code for Flash embedded video):
<div id="flashContent" style="text-align:center;width:100%;">
<span id="FlashPlayer79237" class="Normal" align="center">Bạn cần cài Flash Player để xem được Clip này.</span>
</div>
In this above article, there is a above video. However, when I tried to scan or crawl the content, the video could not run properly (because it could not load correct video link) and only show Install Flash Player plugin words (Certainly, the real web page needs to run some Javascript script or Flash script to obtain the real video link and stream this video for users)
Therefore, how can I render Flash and Javascript script through PHP or ASP.NET or Java? How can I get the correct video link when I crawl the web page? In this case, how can I obtain the correct Flash embedded video (HTML code)?
Thank you so much.
Before I answer, I want to make a note that if you need this information to do anything shady... please don't.
Disclaimer aside, for that particular site it is relatively easy.
The flashvars param (which is probably put there by Javascript) contains a value called xmlPath, which is a url encoded path (relative to their domain name). If you grab that and decode it, you get something like:
/Service/FlashVideo/PlayListVideoPage.asp?id=79237&f=108&t=1
which points to
http://vnexpress.net/Service/FlashVideo/PlayListVideoPage.asp?id=79237&f=108&t=1
If you read that, it's an XML file which contains the URL of the actual video.
I'm not quite sure where that value is generated from. If you needed to do this fully server-side, you could use a headless browser to process it.
I'm currently trying to deliver MP4 video for use in HTML5 video (using video-js) via a PHP script for controlling video access. After some research I was able to get this working, with the help of the stackoverflow article found here. If I navigate to the PHP script, I can view the video as if I were viewing it via its absolute path (for instance localhost/myvideo.mp4 rather than localhost/myscript.php) in Firefox, Safari and IE. My problem is with Google Chrome, which simply shows a blacked out screen with a small media player in the centre, and does nothing.
I did try using a quick rewrite such as localhost/avideo.mp4 which routes to the PHP script, but unfortunately this didn't change anything.
Here's my script:
if (is_file($uri)) {
header('Content-Type: video/mp4');
if (isset($_SERVER['HTTP_RANGE'])) {
$this->rangeDownload($uri);
exit;
} else {
header("Content-Length: ".filesize($uri));
$this->readfile_chunked($uri);
exit;
}
} else {
//error
}
The rangeDownload method has been taken directly from appendix A of this link as suggested in the aforementioned stackoverflow article.
Maybe the problem is with the URL (more specifically, the extension). Normally, you would use Content-Disposition header, but I understand that this is not desirable when delivering content to mobiles.
Try using localhost/myscript.php/myvideo.mp4
It is important not to use the "Content-Disposition" HTTP header, since some phones refuse to accept content when using it.
By including the filename on the URL, you will trick the phone to think it's a real file and to accept it.
Now, when you send the download URL to the customer, you don't normally know yet what device the customer has, so you don't know what file formats the device will support. Therefore, you can't include the filename on that URL, and once again, you will need an intermediate download page. Once more, we will use a URL like:
http://wap.mydomain.tld/get.php/123456abcdef
This time, when the customer connects to download the content, the get.php script will not create a temporary file, but point to another script which streams the file contents.
Supposing the resultant content to download will be "image.jpg", the intermediate download page could point the customer to a URL like:
http://wap.mydomain.tld/download.php/123456abcdef/image.jpg
From ( http://mobiforge.com/developing/story/content-delivery-mobile-devices )
I understand you're using video-js but I recommend using html5media (also check out the github page for more info). I had to make videos available on a website for work and I tried a few things including video-js but html5media was the only one that I could get working in all browsers.
A side note that might help others: One of the requirements was that we hosted all files so that we wouldn't be reliant on third-party servers to serve JavaScript files or flash players, I can't remember if with video-js this was easy but I know with html5media we were able to download flowplayer and have everything on our servers.
And to generate the 3 recommend video formats (mp4, WebM and Theora) I used Miro Video Converter
I am playing with my little PHP project right now and I am struck with a question about how I should approach the image handling. As far as I know, it's either you host the image in your server or let the user provide the link. Given my application is on a shared hosting site, which one better? What are the risks?
User provided
You need to make sure the link is valid
You need to check the content of the link to confirm its an image
You need to be able to check the image on every load
You have to build your html to check the image is still available.
you would also have to confirm that the location of the image is a trusted location
if the image is not on a HTTPS Server and you are, then you can cause issues with browsers.
Self Hosted Image
You can make sure that the image is of the correct format.
You need to watch out for exploits such as GIF Exploit
You can manipulate the image with PHP Dynamically
You can check and validate sizes of images and store on file-system or DB
Requires more bandwidth
If images are dynamic then they can cause high CPU
I would suggest that you go for self hosted image, OR host images on another data centre such as an image host with an open API.
If you your worried about bandwidth then you can create an image upload system that upon upload it uses an image host API to send the image to an external source and then store the image id in the database along with post/user/entity.
Stack Overflow uses the ImgUr for there images,SO has already thought about what your thinking of and have chosen to store externally but upload locally, ImgUR returns data that can be stored, Example below:
<images>
<image>
<name>imgur</name>
<title/>
<caption/>
<hash>UrTHG</hash>
<deletehash>bzEkpCdHPL22Hlp</deletehash>
<datetime>2010-08-14 03:39:23</datetime>
<type>image/gif</type>
<animated>false</animated>
<width>314</width>
<height>115</height>
<size>4413</size>
<views>0</views>
<bandwidth>0</bandwidth>
</image>
<links>
<original>http://imgur.com/UrTHG.gif</original>
<imgur_page>http://imgur.com/UrTHG</imgur_page>
<delete_page>http://imgur.com/delete/bzEkpCdHPL22Hlp</delete_page>
<small_square>http://imgur.com/UrTHGs.jpg</small_square>
<large_thumbnail>http://imgur.com/UrTHGl.jpg</large_thumbnail>
</links>
</images>
This is great because, thumbnails such as small_square,large_thumbnail etc are pre-generated along with meta data such as size,width,height, views etc.
If your worried about CPU usage and server-load then you should revert to the section above regarding external data storage.
If your worried about CPU then you can manipulate the image via GD Libraries and then store a cached version on file-system, update over intervals if need me.
Another down pointer to having user linked images is that when the image is it can be a dynamic image and loggin user data such as what pages that suer is visiting, this one if the main reasons that when your on Facebook and you embed an entity such as a blog post, the images are downloaded and stored on Facebook's CDN, so that outside sources cant tell what and where an IP is.
This should help you decide.
As there has been some discussion about the risk of XSS, i thought i would clear something up a little.
If you choose to allow the user to give you a link to an image you would have to validate the image and not so much the content, the reason why this has to be done is because lets say the user entered the following image location.
javascript:alert('XSS');
If you do not sanitize via PHP with functions like htmlentities() and HTML Purifier library, after you store the above string in your database, when a user attempts to visit the page it would render like so:
<IMG SRC=" javascript:alert('XSS');">
So that every time the page renders you get a dialog box stating XSS, thi is called an XSS Atack, the atack then cauld add another image "url" / "code" that sends certain data such as SESSION ID's to another site that automatically goes to your site and collects data under that ID.
if an attacker entered the following url http://attacker.com/evil.js then the rendered content would be like so:
<IMG SRC="http://attacker.com/evil.js">
As this is an image tag then evil.js would not be processed as javascript, because thats not how the Document Object Model is built, this would be safe to users.
Links on Vulnerabilities
CSRF
XSS Examples
XSS Wiki
Windows Metafile Vuln
Cross Zone Scripting
One thing to be aware of if you are accepting URLs from your users and using them to build an <img> tag: you have to be careful to not be vulnerable to Cross Site Scripting (XSS) attacks, which is an attack where a malicious user is able to inject their own code into your website.
For instance, let's say your code looks like:
$img_url_from_user = $_POST['image_url']; // user inputs a URL in a form
echo '<img src="' . $img_url_from_user . '" />';
A malicious user comes to your form and fills it out:
Now when PHP gets that input and uses it for $img_url_from_user above, the resulting HTML the browser gets is
<img src="invalid.jpg" onerror="alert('attack!')" />
and when the page is loaded, you will see an alert (obviously an attacker can do much worse that this. For instance, they could collect cookies and then use an AJAX call to send the info to their own server). So you have to make sure you sanitize any input you get from your users!
Resources
What are the best practices for avoid xss attacks in a PHP site
Exotic XSS: The HTML Image Tag
I highly recommend pushing your image requests to imgur.com because it appears to be a very reliable image host that cropped up a while back to help support Reddit.com in their need for image hosting. Imgur will allow you to link to images they host and they are completely free. They aren't like tinypic or other sites that will block your images later on.
The only drawback I can see is if someone has a problem with you using a site that also hosts a lot of free porn. Totally your call if you want to go there. It's an open door and anyone can upload anything... but it's stable and reliable so I use it for all my image hosting needs.
One risk of having the app link-dependent is if the link dies, the image dies. One risk of keeping things on your server is, it's possible to disguise any content as an image file.
Another problem with using an external image URL is that (unless hotlinking is disabled on the server the url points to) you might be contributing to someone else's bandwidth problems because most users won't bother uploading the image to a free image hosting site by themselves if the image already exists somewhere in the internet.
Any time you display user-created content on a page, you need to treat it as though it's radioactive. This is a potential XSS vulnerability. Take a look at this cheat-sheet for examples. Some sample inputs that could compromise your users:
document.write('Gotcha!')
http://myserver.com/coolimage.png" onload="document.write('Gotcha!')
><a href=malicioussite.com>View user profile</a>