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How to decode HTML entities using jQuery?
(20 answers)
Closed 8 years ago.
We are doing an AJAX call to retrieve from database. Since our clients may use different languages we encode everything into Unicode to store in the database (saves worrying about collations and such). Now when we fetch such content to be displayed in an input text field it is displaying the Unicode codes. Checked the HTML 4 documentation for input and value is a CDATA which tells me those unicode should be displayed as their character.
From the screen shot attached you can see this is not the case, I'm wondering if there is a way to "force" this behavior.
Since our clients may use different languages we encode everything into ascii to store in the database (saves worrying about collations and such).
IMHO storing html entities into the database is a very bad approach. I would strongly recommend you using UTF-8 encoding everywhere. This is what will save you from worrying about collations and such.
You're passing a JavaScript string full of &#...; numeric character references. JavaScript strings are not HTML-encoded, so your code really does make a JS string containing an ampersand, a hash, and so on.
When you set it as an input's DOM value (val()) naturally those ampersands will still be there. DOM properties are plain strings, not markup. You only need to HTML-encode strings in JavaScript if you intend to make markup out of them for use with innerHTML/html().
So the PHP should not HTML-encode content that isn't going be to inserted into HTML. Use json_encode() to create JavaScript string literals:
$('#js_global_status_input').val(<?php echo json_encode($status_value); ?>);
Related
I'm trying to identify the difference between encodeForHTMLAttribute and encodeForJavaScript. Still, I couldn't find a scenario where untrusted data is used as javascript data values, which broke the code when escaped with encodeForHTMLAttribute, but works securely after escaped using encodeForJavaScript.
I know that for all javascript, its recommended to use encodeForJavaScript. But I like to see the difference.
The answer to your question is boring: The fact is that passing an HTML Entity encoded string to JavaScript is largely an unspecified operation.* JavaScript expects data passed to it to be escaped for JavaScript, with the exception of some API methods, it has no idea what you're sending it.
HTML and JavaScript are different languages. If you'll note, they both have different reserved characters--some the same, meaning they each have reserved characters that make up the language that have to be treated specially when using them in that language.
The correct way to ensure that javascript will always treat incoming code as data, is to escape for JavaScript. Passing it an HTMLEntity encoded String, might work, but we have to say might because that behavior is unspecified. One reason that the question I linked at the beginning partially answers your question is that it is common for JavaScript frameworks to DO that kind of processing on your input... so you better be sure that if that happens, the data is appropriately escaped for JavaScript. Otherwise it will unwrap your HTMLEntity encoding, render and execute script code.
I saved the damning part for last: You can write legal JavaScript with only six characters. And none of these characters are commonly escaped by HTML encoders. Here's an entire guide on using JavaScript escaping like this to evade XSS filters. And for proof that it works, look here.
Or run it yourself in an HTML file on your computer:
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However, if you escape what's between the <script> tags for Javascript... it will be treated purely as data and will not be executed.
*Except for those JavaScript functions that are designed to take HTML-encoded strings as input.
I am using salesforce PHP toolkit in order to insert values of javascript functions (Just in order to document functions I am using, not for execution in salesforce) inside a custom object I have.
In my PHP function I am saving a string like:
(function(d,f){var b={src:(d.location.protocol=="https:"?"https:":"http:")...
after I insert this string using SF API, The result I see in the field is:
(function(d,f){var b={src:(d.location.protocol=="https:"?"...
As you can see, salesforce has added special characters to my string.
I haven't found anyway to pass that.
Any idea's?
The solution was to remove the htmlspecialchars from the string. I didn't think that SF would accept the string without because you could not echo the string without it as well (Due to special characters in my string). But it seems that it does pass the parameter without any issue. I'd be happy to understand that if anyone understands.
I'm trying to determine the best practices for storing and displaying user input in MongoDB. Obviously, in SQL databases, all user input needs to be encoded to prevent injection attacks. However, my understanding is that with MongoDB we need to be more worried about XSS attacks, so does user input need to be encoded on the server before being stored in mongo? Or, is it enough to simply encode the string immediately before it is displayed on the client side using a template library like handlebars?
Here's the flow I'm talking about:
On the client side, user updates their name to "<script>alert('hi');</script>".
Does this need to be escaped to "<script>alert('hi');</script>" before sending it to the server?
The updated string is passed to the server in a JSON document via an ajax request.
The server stores the string in mongodb under "user.name".
Does the server need to escape the string in the same way just to be safe? Would it have to first un-escape the string before fully escaping so as to not double up on the '&'?
Later, user info is requested by client, and the name string is sent in JSON ajax response.
Immediately before display, user name is encoded using something like _.escape(name).
Would this flow display the correct information and be safe from XSS attacks? What about about unicode characters like Chinese characters?
This also could change how text search would need to be done, as the search term may need to be encoded before starting the search if all user text is encoded.
Thanks a lot!
Does this need to be escaped to "<script>alert('hi');</script>" before sending it to the server?
No, it has to be escaped like that just before it ends up in an HTML page - step (5) above.
The right type of escaping has to be applied when text is injected into a new surrounding context. That means you HTML-encode data at the moment you include it in an HTML page. Ideally you are using a modern templating system that will do that escaping for you automatically.
(Similarly if you include data in a JavaScript string literal in a <script> block, you have to JS-encode it; if you include data in in a stylesheet rule you have to CSS-encode it, and so on. If we were using SQL queries with data injected into their strings then we would need to do SQL-escaping, but luckily Mongo queries are typically done with JavaScript objects rather than a string language, so there is no escaping to worry about.)
The database is not an HTML context so HTML-encoding input data on the way to the database is not the right thing to do.
(There are also other sources of XSS than injections, most commonly unsafe URL schemes.)
The short answer is yes, you should still encode all user input.
Whenever you do string concatenation, you need to escape the data correctly. MongoDB supports converting Javascript queries to it's native query language expression in BSON. When doing this there are two contexts to be aware of:
Inside a Javascript string
Everywhere else
If you are concatenating user input outside a string, you really need to be careful. It's really hard to get the escaping right unless the datatype of the variable is an integer or similar where the possible values are known and limited.
The best practice would be to avoid string concatenation whenever possible. You can read more about how MongoDB addresses SQL-Injection here.
I'm making the transition from the Microsoft stack (i.e. WPF) to HTML5 so apologies in advance for the rather amateurish nature of this question.
The topic at hand is HTML encoding and decoding.
Consider an HTML5 app making AJAX calls to a C# back-end via HTTP. The server returns JSON-formatted data exclusively, always making sure to HTML-encode the JSON value fields using HttpUtility.HTMLEncode().
The HTML5 client performs the same process in reverse. All data posted to the server is HTML-decoded first using a simple JavaScript helper function.
All potentially displayable string data in my HTML5 app is stored and passed from place to place in its HTML-encoded form. This scheme is working well for me. But today I discovered HTML5 text boxes and in doing so, noticed something odd. Text boxes don't seem to like encoded text.
If I have a text box defined as such:
<input id="festus" type="text"/>
and update it as follows:
$("#festus").val(someEncodedString)
…the text box shows the actual codes that are embedded into someEncodedString instead of converting those codes to the appropriate characters. I was surprised by this behavior as I assumed that browsers perform the proper escape code interpretation for all DOM elements.
I've tried to abstract away the problem by writing a helper/wrapper for val() called val2():
$.prototype.val2=function(newVal){
return (newVal===undefined)
?iHub.Utils.encodeHTML(this.val()) //getting value
:this.val(iHub.Utils.decodeHTML(newVal)); //setting value
}
[iHub.Utils is a library of helper functions that I wrote]
The idea here is that val2() will appropriately encode the data retrieved from my text box when getting the value, and decode it prior to setting the value. This seems to work but I can't shake the feeling that I must have a fundamental misunderstanding of how encoding/decoding is supposed to work in HTML5.
Is it standard practice to encode/decode data when using text boxes? Are text boxes special somehow in so far as they, unlike other common elements like <p> and <select>, don't perform standard decoding when displaying an encoded input string?
Again, sorry if this is too basic. HTML5 and JavaScript are fairly new to me and my "Intro to HTML5"-type books don't really discuss this topic in any depth.
HTML encoding is for HTML documents. If you were including your value in the HTML document itself, e.g. <input value="10 > 5" />, you would encode it, to make sure that things like > in your value aren't confused with the > that closes the tag.
But when you use JavaScript to set a field's value, there's no room for confusion. You're not modifying a tag like <input.../>; you're modifying a JavaScript object. So you shouldn't HTML-encode the value. If you're using a string variable, like in your example, you don't need to do any encoding at all.
On the other hand, if you're using a string literal to specify the value, you need to encode it as a JavaScript string, e.g. by escaping the ' in $("#festus").val('can\'t'). This is exactly the same reason you do HTML encoding; to avoid confusion with the ' that closes the string.
The only time you'd do HTML-encoding in JavaScript is when you're using it to generate HTML code, e.g. el.innerHTML = '<input value="10 > 5" />';.
Because of this, I would suggest that you not HTML-encode strings in your AJAX responses or requests. Instead, avoid encoding until you're actually generating the kind of code that requires the encoding. So only HTML-encode strings when you're writing HTML, only JavaScript-encode strings when you're writing JavaScript, and so on.
I've got a <textarea> whose value is sent off to the server and stored in a database. This value is then later rendered on different pages in HTML.
What do I need to do to sanitize this? Just remove the HTML tags? (It's already SQL-injection safe because I'm using a stored procedure and parameters.)
Does anyone have a sanitize routine?
Do not sanitize input. Instead encode it when you output it. This is easy to enforce with the .net 4 features (<%: "" %>) or by code-reviewing.
Data should be stored in its native format. Human-readable text has as its native format just text, not some encoded version of it. You cannot easily manipulate encoded text (say doing highlighting of words or replaces).
Not encoding text in the database even saves a little storage space.
Sanitizing input is hard anyway. It is very hard to do more than just encoding everything. Blacklisting HTML tags is a certain way to forget something so don't do it.
Either remove the tags completely, or replace any special characters such as < and > with their HTML entities (<). Whatever server-side language you're using probably already has a function to do this. PHP's htmlspecialchars or strip_tags will do the trick, for example.