CODEWITHSUNDEEP
.netentitieshtml-entities
anon
anon

Reputation:

Alternative to System.Web.HttpUtility.HtmlEncode/Decode?

Is there any 'slimmer' alternative to the System.Web.HttpUtility.HtmlEncode/.Decode functions in .net 3.5 (sp1)? A separate library is fine.. or even 'wanted', at least something that does not pull in a 'whole new world' of dependencies that System.Web requires.

I only want to convert a normal string into its xml/xhtml compliant equivalent (& back).

Upvotes: 5

Views: 10197

Answers (6)

Thom Schumacher
Thom Schumacher

Reputation: 1583

same thing as @marco except the language is powershell

function Invoke-HTMLEncode
{ #https://stackoverflow.com/questions/2779594/alternative-to-system-web-httputility-htmlencode-decode

  param($string)
  if([string]::isNullorEmpty($string))
  { 
   $return = $null
  }
  $result = [system.text.stringbuilder]::new($string.length)
  foreach($ch in $string.ToCharArray()) 
  {
    if([byte][char]$ch -le [byte][char]'>')
    {
     switch ($ch)
     {
       '<' {
         $result.append("&lt;") | out-null
         break;
       }
       '>' {
        $result.append("&gt;")| out-null
        break;
      }
      '"' {
        $result.append("&quot;")| out-null
        break;
      }
      '&'{
        $result.append("&amp;")| out-null
        break;
      }
      default {
        $result.append($ch)| out-null
        break;
      }
     } 
    }
    elseif([byte][char]$ch -ge 160 -and [byte][char]$ch -lt 256)
    {
      #result.Append("&#").Append(((int)ch).ToString(CultureInfo.InvariantCulture)).Append(';');
      $result.append("&#").append(([byte][char]$ch).toString([System.Globalization.CultureInfo]::InvariantCulture)).append(';') | out-null
    }
    else
    {
      $result.Append($ch) | out-null
    }
  }
  $result.ToString()
}

Upvotes: 0

Marco
Marco

Reputation: 6675

For HTML, if using .NET Framework 4.0's System.Net.WebUtility not a viable solution, you could use this:

string HtmlEncode(string s)
{
    if (s == null)
    {
        return null;
    }

    var result = new StringBuilder(s.Length);

    foreach (char ch in s)
    {
        if (ch <= '>')
        {
            switch (ch)
            {
                case '<':
                    result.Append("&lt;");
                    break;

                case '>':
                    result.Append("&gt;");
                    break;

                case '"':
                    result.Append("&quot;");
                    break;

                case '\'':
                    result.Append("&#39;");
                    break;

                case '&':
                    result.Append("&amp;");
                    break;

                default:
                    result.Append(ch);
                    break;
            }
        }
        else if (ch >= 160 && ch < 256)
        {
            result.Append("&#").Append(((int)ch).ToString(CultureInfo.InvariantCulture)).Append(';');
        }
        else
        {
            result.Append(ch);
        }
    }

    return result.ToString();
}

Reson of implementation:

Doing a lot of Replace() on a string would be very inneficient, especially on large strings.

Disclaimer:

This solution was inspired by using JetBrains dotPeek on the .NET Framework 4.0 System assembly.

Upvotes: 4

user90843
user90843

Reputation:

In .NET Framework 4.0, System.Net.WebUtility.HtmlEncode perhaps? Do note that this class is located in System.dll and not System.Web.dll.

Upvotes: 27

Josef Pfleger
Josef Pfleger

Reputation: 74557

Although encoding might seem simple, I strongly recommend to use a library that is in wide-spread use to minimize the risk of security vulnerabilities. Microsoft's Anti-Cross Site Scripting Library provides methods for Html/Xml/Javascript escaping and the respective attribute escapes and should cover most of your web needs.

Upvotes: 1

munissor
munissor

Reputation: 3785

If possible you can "borrow" the HttpUtility class from Mono code and compile it directly a your utility assembly.

Upvotes: 1

Guffa
Guffa

Reputation: 700720

For XML you just have to encode the characters that have a special meaning, so you could get away with something simple like:

public static string XmlEncode(string value) {
  return value
    .Replace("<", "&lt;")
    .Replace(">", "&gt;")
    .Replace("\"", "&quot;")
    .Replace("'", "&apos;")
    .Replace("&", "&amp;");
}

public static string XmlDecode(string value) {
  return value
    .Replace("&lt;", "<")
    .Replace("&gt;", ">")
    .Replace("&quot;", "\"")
    .Replace("&apos;", "'")
    .Replace("&amp;", "&");
}

Upvotes: 5

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