We Keep Coding

Convert From Base64 String C# [duplicate]

This is an odd (to me anyway) query string problem.
I'm using a installation tool that has web serial number validation. Basically the install passes a users email and serial number to a web page (or a controller method for MVC) and that takes the query string arguments and does magic to validate the installation.
One of the arguments is the email address passed in the query string.
I recently has a user who used ‘+’ email addressing to purchase a subscription. All worked well until he went to install the product and had to get past the validation screen.
After doing some digging I found that instead of receiving
‘joe+foo#gmail.com’
The validation code receives
‘joe foo#gmail.com’
Of course the space ruins the validation attempt as his email address is now wrong.
I've spoken with the install tool company (Advanced Installer, best install tool on the planet) and they claim (and I believe them) that the email is sent correctly.
So that leaves me at how do I get the asp.net mvc querystring parser do to the right thing for that particular argument and pass the string with the '+' to the contoller method ?
It's asp.net mvc 5 if it matters.
Thanks for any help you can spare.
UPDATE
The problem is with the sending, not the reception. the plus sign ends up unencoded so it translate to a space= when it get handled by the query string parser.
So what I am looking for is a way to customize the query string parser for that particular URL (and only that URL).
The shortcut to a fix is to replace spaces with a plus sign in the email arg. Simple, but I hate that kind of hackery in my code I;d prefer to have it use a customized parser to that if I need it else where I can just plug it in any way it goes.
You can customize just about everything else in asp.net mvc so I was wondering if there was a way to do the query string pasring in some custom fashion.

Assuming you are calling the URL from javascript, instead of doing this:
url += "?email=" + email;
Encode the value like this:
url += "?email=" + encodeURIComponent(email);
If you are calling the URL from the server, then:
string encodedEmail = Server.UrlEncode(email);
UPDATE
If you can't change where the URL is getting called, then you don't have any other option than:
HttpUtility.UrlEncode(Request.QueryString["email"]);
or:
email = email.Replace(' ', '+');

It looks like I'm going to have to go with my hack solution of swapping space for a plus sign in that particular query string parameter. Not the ideal solution in my way of thinking, but it will do the trick.

How to convert a string to html attribute value as interpreted by a browser in C#

I need to validate user input for an href on the server side and need to make sure only http:// and https:// are allowed as a protocol (if specified at all.) The objective is to eliminate possible malicious code like javascript:... or anything alike.
What makes it difficult is the number of ways the colon could be encoded in such string e.g. :, &#58, :, &#x0003A , :. I'd like to transform the value and see it as the browsers do before they render the page.
One option could be building a DOM document using AngleSharp as it does the perfect job when parsing attributes. Then I could retrieve the value and validate it but it seems somewhat of an overkill to build the whole DOM tree just to parse one value. Is there a way to use AngleSharp to parse just an attribute value? Or is there a lib which I could use just for this task?
I also found this question, but the method used in there does not really parse the URIs the way browsers do.

You want the HtmlDecode() method. You may need to add a reference to the project to use it.

Pass URL with single quote and ampersand in Outlook using a .NET website

I have a web page that uses a webmail service to send emails. This is on an company intranet using a Microsoft Exchange server. My website created an email with a link to an image handler on my website. In my code, I can print some debug messages and I see:
<img src='http://tav.target.com/VIBEHandler.ashx?id=z064441_45975&type=Amazing'/>
But in the email, when I view the source code, I see this:
<img src="http://tav.target.com/VIBEHandler.ashx?id=z064441_45975&type=Amazing"/>
My single quotes changed to double quotes (no big deal).
&
changed to
&
This causes the URL to not work and images appear as the red "x", indicating a missing image.
How can I preserve my URL?

Your 3rd party emailing service might be converting your HTML document to a valid XML document for compatibility reasons.
http://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references
Basically, in XML, an ampersand character represents and XML entity, and can not be used unless you place the text within a CDATA node. Your 3rd party service seems to just be converting the & to & , which would work to safely display the value, but doesn't do too much for a URL.
http://www.w3schools.com/xml/xml_cdata.asp
If I were in your situation, I would URL encode the image URL when generating the HTML document that is being sent out. This way, it is both a proper link, and a valid XML string.
HttpUtility.UrlEncode(myUrlString);
http://msdn.microsoft.com/en-us/library/4fkewx0t%28v=vs.110%29.aspx
Hope this helps!

The best solution we could come up with is to use a single variable with multiple values separated with an underscore. This eliminates the need for the '&' symbol entirely and makes everything happy and compatible.
The URL is basically a link to an image handler so we can include images in emails without the use of attachments, shared drives, etc. The image handler can also do things like merge images together to create a single image (WAY better than trying to overlap images in emails which almost NEVER works). I simply added some code to the image handler that can check for and dissect the "meta-variable" in my URL.
http://sample.com?var=ONE_TWO_THREE
http://sample.com?var1=ONE&var2=TWO&var3=THREE
The URL now looks more clean and can have as many variables as I want so long as I put everything in the exact correct order, read it all in using the same sequence, don't miss anything, and document everything well. I COULD go one step farther and specify what each variable means:
http://sample.com?var=first-Nicolai_last-Dutka_age-34_etc-foobar
But that just tells the whole world what all my variables mean! Hypothetically, I could do:
http://sample.com?var=24154#kja&nl897q45pjkh8&&^HJ435
Then it would be up to me to determine where the breaking points are to bust that up into the variables:
24151, kja*, n1897, 45, etc
Of course, I'm not going to be that complex and will likely just stick to:
http://sample.com?var=ONE_TWO_THREE
Enjoy!

C# Equivalent for stringByAddingPercentEscapesUsingEncoding?

I'm trying to find a way to mimic the behavior of stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding from the iPhone, using C# (for Windows Phone).
I don't know anything about iPhone programming, and a web search for that doesn't seem to provide any document pages that might explain what it actually does to help me figure out how to mimic it. I mean, I can see that it "percent escapes" a string using an encoding, but I can't find any examples of what it does to confirm that the output I would be getting is correct. Is it just a simple URL Encode?

I'm not pretty sure if I understood your question, but HttpUtility.UrlEncode might be what you're looking for. At MSDN you'll find it's definition and examples.
Update: this is the official doc from Apple, regarding the iOS method you mentioned.

try this for urls
var uri = new Uri (url);
var nsurl = new NSUrl (uri.GetComponents (UriComponents.HttpRequestUrl, UriFormat.UriEscaped));
UIApplication.SharedApplication.OpenUrl (nsurl);

Though this question is very old, but for those still looking for an answer: HttpUtility.UrlPathEncode is the C# equivalent of stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding] in Objective C. This is what one should use while composing email etc. in mobile apps / iOS / iPhone app (Xamarin). The difference between HttpUtility.UrlEncode and HttpUtility.UrlPathEncode is -
The UrlEncode method converts each space character to a plus character (+). The UrlPathEncode method converts each space character into the string "%20", which represents a space in hexadecimal notation. Use the UrlPathEncode method when you encode the path portion of a URL in order to guarantee a consistent decoded URL, regardless of which platform or browser performs the decoding.
Also, though the MSDN docs recommend to use UrlEncode instead of UrlPathEncode, only latter is what will work in the referenced scenario.
[Update] Doesn't work same in Android (Xamarin), if you have encoded strings, you'd need to decode them back using HttpUtility.UrlDecode.

passing and getting too large query string in asp.net

i integrating with an software, where they sending their document to my url with too large query string value. i.e. more than 75000 char for a parameter. i am in a R&D phase to check whether integration is works. i came to know that browsers will limit the query string. i want to get their document into to my server. i google but not get the answer. the url is in following fashion
Http:\\myurl?document=thierdocument in base64 encoded format
guide me to overcome the problem

This is not going to work. The query string is limited to a few thousand characters depending on the browser (i.e. 2083 characters for IE). Use a HTTP POST instead and put the document in binary format in the body of the request.
The main idea of a URL was to be a Uniform Resource Locator, not to pass all the data as part of the URL itself. You cannot work around the browser limits on URLs (neither should you arguably) - an alternative could be passing the document id in form of a number or Guid, then looking up that document to process as part of your page.

My suggestion is to move the data from query string, to post form.
My suggestion is to move the data from query string, to post form.
Why ?
one reason is the the url data, including your big string, is used to know if the page is going to cached by the browser or not. So I think that browser him self have a problem remeber this big string.
other reason is that this url is travel as it is, a big one, and is very possible to not reach the target.
The 2083 charatercs in IE I think that is refered only on URL, not on the included data.

You will have to do it using POST query.
Taken from What is the limit on QueryString / GET / URL parameters?
The spec for URL length does not dictate a minimum or maximum URL
length, but implementation varies by browser. On Windows: Opera
supports ~4050 characters, IE 4.0+ supports exactly 2083 characters,
Netscape 3 -> 4.78 support up to 8192 characters before causing errors
on shut-down, and Netscape 6 supports ~2000 before causing errors on
start-up.