Setting up URL Rewrite rule for a specific domain - iis

Question

For local dev testing, I need to catch all requests to www.somedomain.com/XXX (where X is the path), and send them on to localhost/somevdir/XXX.
I've added this to my HOSTS file (c:\windows\system32\drivers\etc):
127.0.0.1 www.mydomain.com
Then, in IIS8 (Windows 8), I've added a binding to my "Default Web Site" for the host www.mydomain.com. This works, I can now browse www.mydomain.com/test.html and see a test html page. My virtual dir is inside the Default web site. I then add a URL Rewrite URL to the web site for the last bit:
<rewrite>
<rules>
<rule name="mydomain.com" stopProcessing="true">
<match url="^www.mydomain.com/(.*)" />
<action type="Rewrite" url="localhost/MyVDir/{R:1}" logRewrittenUrl="true" />
</rule>
</rules>
</rewrite>
But - that doesn't work. I get a 404 so it looks the the match never happens. I've tried redirect and rewrite, and I've tried without the ^ in the regex and a few other regex tweaks. Can someone explain what I've done wrong?

Answer 1

I think the following should work:
<rule name="mydomain.com" stopProcessing="true">
<match url="(.*)" />
<conditions logicalGrouping="MatchAll">
<add input="{HTTP_HOST}" pattern="^(mydomain\.com|www\.mydomain\.com)$" />
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
</conditions>
<action type="Redirect" url="http://localhost/MyVDir/{R:1}" redirectType="Temporary" />
</rule>
The match on any URL makes sure the conditions are checked, and the HTTP_HOST server variable seems the most reliable way of checking the requested hostname. You could remove the REQUEST_FILENAME input condition, but it works as quite a nice sanity check to make sure static files are always served.

Answer 2

The following is better for catching both www. and non-www. versions of the domain so that you don't have to write the domain twice, which could possibly cause errors with being twice as likely to write a typo. (The parenthesis with the ? character means optional in regex terms.)
<rule name="mydomain.com" stopProcessing="true">
<match url="(.*)" />
<conditions logicalGrouping="MatchAll">
<add input="{HTTP_HOST}" pattern="^(www.)?mydomain\.com$" />
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
</conditions>
<action type="Redirect" url="http://localhost/MyVDir/{R:1}" redirectType="Temporary" />
</rule>