Using C# Regular expression to replace XML element

Question

I'm writing some code that handles logging xml data and I would like to be able to replace the content of certain elements (eg passwords) in the document. I'd rather not serialize and parse the document as my code will be handling a variety of schemas.

Sample input documents:

doc #1:

   <user>
       <userid>jsmith</userid>
       <password>myPword</password>
    </user>

doc #2:

<secinfo>
       <ns:username>jsmith</ns:username>
       <ns:password>myPword</ns:password>
 </secinfo>

What I'd like my output to be:

output doc #1:

<user>
       <userid>jsmith</userid>
       <password>XXXXX</password>
 </user>

output doc #2:

<secinfo>
       <ns:username>jsmith</ns:username>
       <ns:password>XXXXX</ns:password>
 </secinfo>

Since the documents I'll be processing could have a variety of schemas, I was hoping to come up with a nice generic regular expression solution that could find elements with password in them and mask the content accordingly.

Can I solve this using regular expressions and C# or is there a more efficient way?

Answer 1

Here is what I came up with when I went with XMLDocument, it may not be as slick as XSLT, but should be generic enough to handle a variety of documents:

            //input is a String with some valid XML
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(input);
            XmlNodeList nodeList = doc.SelectNodes("//*");

            foreach (XmlNode node in nodeList)
            {
                if (node.Name.ToUpper().Contains("PASSWORD"))
                {
                    node.InnerText = "XXXX";
                }
                else if (node.Attributes.Count > 0)
                {
                    foreach (XmlAttribute a in node.Attributes)
                    {
                        if (a.LocalName.ToUpper().Contains("PASSWORD"))
                        {
                            a.InnerText = "XXXXX";
                        }
                    }
                }    
            }