URL Decoding in PHP not working as supposed to be - php

I am trying to decode this URL string using PHP's urldecode function:
urldecode("%3CR201810579707%3E%20%3C20180828%3E%20%3C20180912%3E%20%3C1033.00%3E%20%3CY%3E%20%3C0.00%21NA%3E");
This is supposed to output...
<R201810579707> <20180828> <20180912> <1033.00> <Y> <0.00!NA>
...but instead is ouptutting this
<20180828> <20180912> <1033.00> <0.00!NA>
I've tested the string in a php online decoder with great success, but can't seem to do this operation server side. Any ideas?

If you're printing the result on a web page, the angle brackets will be treated as tag delimiters. You can display it literally by calling htmlentities():
echo htmlentities(urldecode("%3CR201810579707%3E%20%3C20180828%3E%20%3C20180912%3E%20%3C1033.00%3E%20%3CY%3E%20%3C0.00%21NA%3E"));

Related

PHP Escape a string if it hasn't already been escaped with entities

I'm using a 3rd party API that seems to return its data with the entity codes already in there. Such as The Lion’s Pride.
If I print the string as-is from the API it renders just fine in the browser (in the example above it would put in an apostrophe). However, I can't trust that the API will always use the entities in the future so I want to use something like htmlentities or htmlspecialchars myself before I print it. The problem with this is that it will encode the ampersand in the entity code again and the end result will be The Lion&#8217;s Pride in the HTML source which doesn't render anything user friendly.
How can I use htmlentities or htmlspecialchars only if it hasn't already been used on the string? Is there a built-in way to detect if entities are already present in the string?
No one seems to be answering your actual question, so I will
How can I use htmlentities or htmlspecialchars only if it hasn't already been used on the string? Is there a built-in way to detect if entities are already present in the string?
It's impossible. What if I'm making an educational post about HTML entities and I want to actually print this on the screen:
The Lion&#8217;s Pride
... it would need to be encoded as...
The Lion&amp&semi;&num;8217&semi;s Pride
But what if that was the actual string we wanted to print on the string ? ... and so on.
Bottom line is, you have to know what you've been given and work from there – which is where the advice from the other answers comes in – which is still just a workaround.
What if they give you double-encoded strings? What if they start wrapping the html-encoded strings in XML? And then wrap that in JSON? ... And then the JSON is converted to binary strings? the possibilities are endless.
It's not impossible for the API you depend on to suddenly switch the output type, but it's also a pretty big violation of the original contract with your users. To some extent, you have to put some trust in the API to do what it says it's going to do. Unit/Integration tests make up the rest of the trust.
And because you could never write a program that works for any possible change they could make, it's senseless to try to anticipate any change at all.
Decode the string, then re-encode the entities. (Using html_entity_decode())
$string = htmlspecialchars(html_entity_decode($string));
https://eval.in/662095
There is NO WAY to do what you ask for!
You must know what kind of data is the service giving back.
Anything else would be guessing.
Example:
what if the service is giving back & but is not escaping ?
you would guess it IS escaping so you would wrongly interpret as & while the correct value is &
I think the best solution, is first to decode all html entities/special chars from the original string, and then html encode the string again.
That way you will end up with a correctly encoded string, no matter if the original string was encoded or not.
You also have the option of using htmlspecialchars_decode();
$string = htmlspecialchars_decode($string);
It's already in htmlentities:
php > echo htmlentities('Hi&mom', ENT_HTML5, ini_get('default_charset'), false);
Hi&mom
php > echo htmlentities('Hi&mom', ENT_HTML5, ini_get('default_charset'), true);
Hi&amp&semi;mom
Just use the [optional]4th argument to NOT double-encode.

php string not usable in method file_get_contents($var)

I have a method that scrapes data from a url and returns that as a string variable. Currently the method is working if i put in my own url, but when i insert a generated url it doesnt work.
e.g.
The following string is working if I insert it into a variable, and pass it:
http://www.rijkswaterstaat.nl/apps/geoservices/rwsnl/awd.php?mode=html&projecttype=windsnelheden_en_windstoten&category=1&loc=ZBWI&net=LMW
But this string is being generated by another source. The result of my attempt to fetch it is (var_dump()):
string(154) "http://www.rijkswaterstaat.nl/apps/geoservices/rwsnl/awd.php?mode=html&projecttype=windsnelheden_en_windstoten&category=1&loc=ZBWI&net=LMW"
The string is only 138 characters, however it prints string(158). I think this has something to do with the fact it is not working, but i'm not even sure...
Does anyone have any idea how to clean this up? I have found other questions with the question why var_dump() is showing another value then the length of the string, and that had something to do with unvisible characters, but no real solution is given anywhere.
Thx
154-138 = 16
You have 4 & in the string
& HTML encoded is &
So your string seems to be HTML encoded - in the browser you don't see the encoding unless you "View Source".
You can use html_entity_decode() to decode the string or, if possible, make sure that you get a string that is not encoded for HTML output in the first place.

Sending HTML string via POST to PHP. Get weird characters when ECHOing it out

So I am making a simple script where I send a HTML string via POST to PHP and when I try to echo it out it gets encoded with some weird characters
The string Im sending:
'Yo <i>whats up</i>'
What I get when I echo it out with PHP
Yo+%3Ci%3Ewhats+up%3C%2Fi%3E
What is going on here? Is there some PHP method I can use to revert it back to the original HTML string?
You want to use
echo htmlspecialchars(urldecode('Yo+%3Ci%3Ewhats+up%3C%2Fi%3E'));
The reason is that your data gets x-www-form-urlencoded for posting. So on the server-side, you have to decode it again - that's what urldecode() does.
htmlspecialchars() prevents your HTML-Tags to be rendered as such so they are just displayed as a string (if that's what you want).
So, in an HTML context, echo urldecode('Yo+%3Ci%3Ewhats+up%3C%2Fi%3E'); would output
Yo whats up
And if you also wrap it with htmlspecialchars(), your output would be
Yo <i>whats up</i>
again.
It looks like your post string is being encoded for url.
you can use urldecode to remove these characters
echo urldecode($_POST['string']);

Allow certain characters to pass through $_GET?

I wrote a script that when you enter a textbox, it will open an invisible iframe to a .php file with $_GET of what they wrote into the textbox.
However, for example, if I type: '<3' in it, this is what happens.
PHP determins that the $_GET[s] is blank! Users cant put a simple <3 symbol without getting that error.
Another problem is quotes, if I write any quotes, it will end the entire SRC property.
What should I do? Should I do something with javascript, or even PHP? Please let me know!
Thanks!
Use urlencode to encode the inputted string into a valid one for URL use.
Also be very cautious when allowing user input into your PHP script through the URL. Make sure you do proper checks/sanitization, especially if database operations are involved.
It looks like your iframe is generated by JavaScript, so all those answers that include PHP functions are useless. The data isn't even reaching PHP, so how can any PHP function hope to help?
Instead, try using urlencode from PHPJS, since none of JS's functions really handle all cases well, and this makes it easy for you to use PHP's urldecode to retrieve the data.
You need to encode that character as <.
Regarding double quotes, you can use this trick.
attr='Your string can "contain double quotes"'
or
attr="Your string can 'contain double quotes'"
but while specifying variable=values in url, you don't need to user double quotes, you can directly assign the values.
like
url="test.php?var1=123&var2=345"
rest about sending the <3 characters, you can check for url encoding in javascript & PHP whichever applicable!

Ampersand problem in XML when creating a URL String

I am working with an XML feed that has, as one of it's nodes, a URL string similar to the following:
http://aflite.co.uk/track/?aid=13414&mid=32532&dl=http://www.google.com/&aref=chris
I understand that ampersands cause a lot of problems in XML and should be escaped by using & instead of a naked &. I therefore changed the php to read as follows:
<node><?php echo ('http://aflite.co.uk/track/?aid=13414&mid=32532&dl=http://www.google.com/&aref=chris'); ?></node>
However when this generates the XML feed, the string appears with the full &
and so the actual URL does not work. Apologies if this is a very basic misunderstanding but some guidance would be great.
I've also tried using %26 instead of & but still getting the same problem.
If you are inserting something into XML/HTML you should always use the htmlspecialchars function. this will escape your strings into correct XML syntax.
but you are running into a second problem.
your have added a second url to the first one.
this need also escaped into url syntax.
for this you need to use urlencode.
<node><?php echo htmlspecialchars('http://aflite.co.uk/track/?aid=13414&mid=32532&aref=chris&dl='.urlencode('http://www.google.com/')); ?></node>
& is correct for escaping ampersands in an XML document. The example you've given should work.
You state that it doesn't work, but you haven't stated what application you're using, or in what way it doesn't work. What exactly happens when you click the link? Do the & strings end up in the browser's URL field? If that's the case, it sounds like a fault with the software you've viewing the XML with. Have you tried looking at the XML in another application to see if the problem is consistent?
To answer the final part of your question: %26 would definitely not work for you -- this would be what you'd use if your URL parameters needed to contain ampersands. Say for example in aref=chris, if the name chris were to an ampersand (lets say the username was chris&bob), then that ampersand would need to be escaped using %26 so that the URL parser didn't see it as starting a new URL parameter.
Hope that helps.

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