I'm playing with the spotify play button and try to make it display an arbitrary set of tracks, that I'm giving as a comma-separated list of IDs.
It works well most of the time, but it can happen that the button is not properly rendered, and displays the Spotify Developer Page instead, like shown here: http://xben.free.fr/spotify/
I feel like it happens when using an important number of tracks (more than 80).
Has one of you experienced the same problem, or know if there is a limitation? I went through the doc and it only mentions a 1000 tracks restriction when using an existing playlist.
Yes, it is known limitation that trackset uris can not be longer than around 80 tracks (depending on your trackset title).
The reasoning for the arbitrary limit goes something like this: It is the longest possible url that you can send to older IE browsers. We want it to work the same across all browsers. If it doesn't work in one, it shouldn't work in the others either.
Two problems however.
The way it is implemented, just setting suhosin.get.max_value_length = 2048 in php conf. If it is too big, suhosin will just drop the parameter, making the request look like https://embed.spotify.com which will redirect to the developer site. Not the best of error messages. We will fix.
The limit should be documented. We will fix. Maybe even raise the limit and tell people to be vary of certain browsers.
(I work at Spotify)
Related
I would like to know if there is a way to prevent the use of userscripts on my browser game site?
Many use Greasemonkey to have advantages over other players, and I would like a way to disable these scripts.
I found this old article, "How To Disable Greasemonkey On Your Web Site", but it's from 2005 and doesn't seem to work.
Combating a smart scripter is tough. They have the upper hand since their script can touch the page before your server does, and can block or replace just about anything. See this answer to a very similar question.
Your smartest, and most cost-effective countermeasure is to sanction the users who are "gaming" the game. Attack the burglar, not the lock-pick.
If you insist in a tech war with your users, nothing you do will block everybody, but you can make them work for it.
Here are some things you can do make life harder for scripters:
Frequently change the structure of the page, especially element ID's and CSS class names. If you can, periodically insert or remove elements, so that the key <div> is not always the 3rd one in the second <table>, for example.
Every time you make a change, monitor your logs for users who get a sudden decrease in performance or usage -- for however many hours or days it takes them to adapt their scripts.
Likewise, frequently change your javascript filenames, and change the names of any variables or functions that the scripter may use.
Write your click and keyboard event-handlers to only work for trusted events, for browsers that support it.
You can put key text, including countdown timers, in images with unpredictable names. Making it hard for the script to detect key events. Needing to do OCR ramps up the skill-level required by a Greasemonkey scriptwriter, considerably. (At least for now.)
If you move the key game action into Flash, it becomes an order of magnitude harder to script for. They may even have to reverse engineer your flash and replace it with one that has scriptable hooks. Switching to Flash will annoy and drive off users (like me), though.
See that answer for more but, again, the best and most cost-effective approach is to sanction the offending user(s). Be sure that your Terms of Service specifically forbids what they are doing, though.
As addition to Brock Adams' own answer, here's couple methods for finding a possible scripter.
Timed function that checks DOM tree and search for added elements that are not your code's creation, or look for missing elements.
Primarily finds scripter who alters UI, yet haven't read/understood the game's js-source.
Client-side.
"Missing element"-search may get false positives from people who use something like AdBlock Plus. Not really false positive, if aim is to rank them out, too.
Inspect cookie content and look for hints of user added content.
If scripter has to transfer information from page/session to another, and has/knows no other method, he may attempt to use cookies for this.
Inspect query/hash in URL for content not added by your code.
It's possible to try to transfer information to other pages by altering links.
Hash-content (# in URL) is accessible only client-side.
Inspect session/localStorage.
Client-side.
Disable access thru anonymizing services, like anonym.to.
Circumventable, but makes life harder for people using unwanted online-tools.
Allow access to game-page only if referer is correct, otherwise redirect to login-page.
Another method to limit access to game-pages from outside sources.
If you want to be a pain, kill active session when redirecting.
NOTE: All client-side functions can be circumvented by scripter who understands the code.
NOTE: Usage of these requires some wisdom and good planning. If doing things wrong, then with client-side stuff you risk of kicking users' browsers on knees or DDoSing your own server. Or you may end up banning least half of the userbase after an update on your own code, if you use too much automation.
Here's one of my scripts. It could definitely still use some work, but the framework is there (though you may need to wrap everything in a big function to make variables private)
var secureElements,secureTags,secureTagLoop,secureLoop,var secureReporter = secureAnalyzationFunction = 0;
function analyze(secureAnalyzation){
if(secureAnalyzation.indexOf("function ")!=-1){
secureAnalyzationFunction = secureAnalyzation.substring(secureAnalyzation.indexOf("function ")+9,secureAnalyzation.indexOf("()"));
secureAnalyzationFunction = secureAnalyzationFunction+"=undefined;";
eval(secureAnalyzationFunction);
}
}
function secure(){
var secureTags = ["script","link","meta","canvas"];
for(secureTagLoop=0;secureTagLoop!=secureTags.length;secureTagLoop++){
secureElements = document.getElementsByTagName(secureTags[secureTagLoop]);
for(secureLoop=0;secureLoop!=secureElements.length;secureLoop++){
if(secureElements[secureLoop].outerHTML.indexOf("verified")==-1){
analyze(secureElements[secureLoop].outerHTML);
secureElements[secureLoop].parentElement.removeChild(secureElements[secureLoop]);
secureLoop--;
secureReporter++;
console.log("Deleted "+secureReporter+" foreign elements.")
}
}
}
}
window.onload = function() {
secure();
setInterval(secure,1500);
};
Can someone identify ONE WEB PAGE where <meta property="og:audio:artist"> and <meta property="og:audio:album"> are actually working to set the Artist and Album when sharing the URL of the page?
I have been banging away at http://www.coises.com/songs/sfcarol.htm for hours, trying every permutation of order of META tags, XML tag formats (even though it’s an HTML page), etc. (Note: though I have a home-grown share button on the page, I’m talking about sharing the URL of the page in the status box on Facebook itself as the test case.)
All I can get is that all words in the title are capitalized, even though it isn’t specified that way, and the Artist and Album are always Unknown. (For another song/page, "8/9/95", even the title won’t show.) The description also doesn’t show when doing the share, though it does show in the posted story.
I tried searching, and I tried places like ReverbNation and SoundCloud, but nobody seems to use the og:audio tags. (For videos, copying the way YouTube does it appears to work perfectly, http://www.coises.com/songs/risingup.htm being an example.) If I could see just one working example, I suspect I could figure it out.
My own song pages (e.g., http://www.coises.com/songs/floodplain.htm and most other song pages on my site) are now working examples.
It turns out the problem was simple: og:audio:artist and og:audio:album do not work unless og:audio:title is also supplied. I had assumed that would default to og:title; it seems it must be explicitly specified.
The linter still says the og:audio:{title|artist|album} tags are not allowed, but they work.
Those OG tags still seem to be in beta. below I've included the linter results for five different websites that facebook is in partnership with.
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fmog.com%2Fm%2Ftrack%2F57587005
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.deezer.com%2Fmusic%2Ftrack%2F6461440
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.rhapsody.com%2Fartist%2Ftrombone-shorty%2Falbum%2Ffor-true
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.vevo.com%2Fwatch%2Fj-cole-featuring-trey-songz-j-cole-1%2Fcant-get-enough%2FUSQX91101318
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fopen.spotify.com%2Ftrack%2F3ssX20QT5c3nA9wk78V1LQ
I see this referenced a lot: http://ajaxify.com/run/crossframe/
And I noticed now it's no longer working for the IFRAME (child) to change the parents hash.
I've been spending a few hours trying various things wondering why this isn't working anymore -- then I finally realized that the example I originally based it on was down too.
Can anybody confirm?
-
-
I need to use a cross domain iframe to take care of an order upload form that our shopping cart doesn't support, and I need the form to return an order ID to the parent, so that I can associate the data between the two servers.
Any recommendations or directions to head in would be appreciated.
I'm not looking for a shortcut or somebody to do my work. I've been reading all day... I just need a nudge in the right direction.
Thanks!
It is partly browser-specific. For instance, some browsers don't allow a nested child frame (iframe within an iframe) to change its parent's fragment. See this blog entry. But the basic functionality still works in recent browsers. This demo, which has an iframe change its parent, and vice versa (single level) works fine in Firefox 3.5.9 and Chrome 5.0.375.99.
The demo you gave also works both ways in that version of Firefox. It doesn't allow the child to change the parent in Chrome. The main difference seems to be that the working one uses parent.location, while the broken one uses parent.window.location.hash.
The best solution for recent browsers is postMessage. If necessary, you can also use a server proxy.
I wish to block ALL my content from any users using an ad-blocking browser extension (ie. Adblock Plus for Firefox, Adthwart for Chrome).
How can I acheive this? Is there a server-side solution? Client-side?
Edit 1
This question regards the detection of ad-blocking browser extensions:
Detecting AdBlocking software?
I'm concerned with post-detection action.
Edit 2
A duplicate question was asked after mine, so I thought I'd link to it here:
Prevent Adblock Users from Accessing Website?
To detect if the user is blocking ads, all you have to do is find a function in the ad javascript and try testing for it. It doesn't matter what method they're using to block the ad. Here's what it looks like for Google Adsense ads:
if(typeof(window.google_render_ad)=="undefined")
{
//They're blocking ads, do something else.
}
This method is outlined here: http://www.metamorphosite.com/detect-web-popup-blocker-software-adblock-spam
It's like trying to block users from reading your contents while standing rather then while sitting. It's silly, and it's likely to drive visitors off your site. The last time i saw a "you're using adblock, that hurt web developing bla bla" i jst blocked that div with the element hiding helper. It was fun i admit. Most sites are almost unreadable as now, with flashing ads and pale contents. A good quantity of ads are, also, malevolent, disguised as part of the site they're in takes the user to bad places.
That's why you should not. If you still want to, bad news, you can't. As long as i can write $('.ad').hide() in my console, nobody can stop me from adblocking something. I sometimes give up when ads divs have a very generic class, id, or they haven't any, so that it's difficult to target them with the adblock element hiding helper (of course if they are not in the lists, in that case i dont even know they exists). So the best you can do probably is give to ads a class of .content or something you use also in other parts of the site. It's not much, but it' all you can do. And just because you can, it does not mean you should. The web marketing model have to change, and it will.
That I know of this is not directly possible. Most add blockers work by locking at the URLs that are being "requested" and either blocking directly, or looking at the content/mime-type and blocking based on that.
You might be able to do something by looking for signs of the adblocker, but this will be difficult at best.
Although I love my adblocker, it's about answering questions. You could check if an url that would normally be blocked by an adblocker is reachable, and continue only if that image/bla in question is loaded. otherwise, you just don't.
How can we restrict a user from saving the page?
Please provide some tips to disable File->Save and View Source options
EDIT: Obviously it can't be done, and probably shouldn't be attempted. But possibly a more interesting variant on this question is how can we make is sufficiently hard for a user to save a page in a usable format such that it is not worth their while doing so? The question doesn't pose a value, but say we were protecting an article subscription site where the user is paying a few hundred dollars per annum for continued access to text.
Since the page has been sent to the client, there will always be a way to get that information. Trying to stop a user from doing this will only frustrate them.
The only way to have a user not be able to save a file is to not send it to them.
While the best answer is "Don't do this," there are ways to make it more difficult for them. And since the point of this site is actually answer the question even if it's bad, here is the best way:
First you'll need to have the page open in a new window where you turn off the address bar and toolbar and everything else. That will make it so the user can't easily get to the File menu at all. To do this you'll need a "splash" page that the user loads to and then when they click a link, it opens the popup that serves the main content of your page. Details on how to create popups without things like the toolbar are here:
http://blazonry.com/javascript/windows.php
Then you'll want to add some javascript to each page that prevents the user from right clicking. Here is one method:
http://javascript.about.com/library/blnoright.htm
Finally, if it's your Javascript code that you don't want to be seen, then obfuscating your code is a pretty effective way to do that. They can still see the code if they have much know-how, but the obfuscated code would be a gigantic pain to actually interpret. There are lots of obfuscators out there; here is a free web-based one:
http://www.javascriptobfuscator.com/
This is far from foolproof. It will stop all "casual" users, but any power user will probably be able to easily figure out a way around it. Still if the idea is to at least prevent a good majority of it then this should suffice.
Update for updated question:
To address your new expanded question, I would say the best way to accomplish what you're saying is to use a format that supports DRM. Adobe Acrobat would probably be the best choice because almost everyone has the reader installed. You can prevent PDF files from being saved to the computer so that they can only be loaded from the webpage by a logged in user. The user could still do a screen capture of the document itself which I don't believe is preventable (unless Adobe Reader has some security in place for this, which they might) but it should be sufficient security for most uses.
Don't do it.
Seriously, if the user can see the page in their browser they can see the source code and/or save it to their computer.
You are fighting a losing battle here.
What about the browser's cache? It can be saved from there.
What about a print screen? That could also save the page.
The only way to prevent a user from saving something is to not show it to them in the first place.
It's really a waste of time and resources to try and do this in html as any method you use can be trivially circumvented.
Instead I would use some other technology to display the data - you can never get around a screen capture. but if you're for instance displaying text and you want to make it hard for the use to save that text for use elsewhere then possible options include
PDF - which can disable save and print. There are extensions to most popular web languages that will write a pdf on the fly. Indeed you might be as well just to go down the DRM route with Adobe and embed a document
Flash - most probably via Flex which could be used to write a general-purpose app to display text and images. The advantage of Flash is that it's easier to set up links than pdf.
Or something else, a custom java applet, or even a vrml plugin and display the text in 3D!
In all cases you could display text against a disruptive background to make OCR more difficult, and images could be watermarked. However nothing is going to stop a determined and resourceful viewer, although you can possibly make it sufficiently hard that it's not worth their time.
The least you can do is... the content is generated dynamically by Javascript. In that way, they cannot simply save it. Of course, in FX, they can still view the generated code and then copy&paste. however, normally people cannot save the page.
It shouldn't be an issue, but if you really don't want a user from seeing your code (javascript, css or html) for some reason, than you could use some obfuscation tool which makes the code less readable.
Try javascript "encoding" and obfuscation.
Something like
if(document.location == 'mydomain.com') {
content = getAjax('mycontent.xml');
// content will hold something like 72, 94, 81, 99, ... - encoded ASCII codes
document.write(String.fromCharCode(content));
}
It will always be possible to save the page, but for non-technical guys it will be harder to make it work.
There are 2 protections
domain name
converting ASCII
It's only pseudocode, but I think you get the idea.
add these to code sets in script tag
document.addEventListener('contextmenu', function (e) {
e.preventDefault();
});
document.onkeydown = function (e) {
return false;
};
I'd like to add one more method which, imho, is hard to circumvent: Ctrl+S! (for me, Apple+S)
how can we make is sufficiently hard for a user to save a page in a usable format such that it is not worth their while doing so
Nothing hard: add on every page: "Personal property of John Stealer, company Zetabeta, paid with credit card 756890987654, billing address ..., subscription expires 12/20".
This is an "extended text format" that I just invented... it has an amazing property: though it looks like a regular text, user is much less willing to print it out and give to others...