IIS rewrite rule to check for querystring and add it if its not there

REMOVED NON RELEVANT INFO AND EDITED

SO if you are using IIS7 download the URL Rewrite Module. All the instructions and info you need are included at that link.

Hope that helps.

My solution would be use conditions for that. By matching the conditions against the {QUERY_STRING} you can use back references to use them in the redirect URL.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="Redirect" stopProcessing="true">
                    <match url="(.*)" />
                    <conditions trackAllCaptures="true">
                        <add input="{QUERY_STRING}" pattern="&amp;?(beta=[^&amp;]+)&amp;?" />
                        <add input="{QUERY_STRING}" pattern="&amp;?(gamma=[^&amp;]+)&amp;?" />
                        <add input="{REQUEST_URI}" pattern="^/redirect" negate="true" />
                    </conditions>
                    <action type="Redirect" url="/redirect?{C:1}&amp;{C:2}" appendQueryString="false" redirectType="Found" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

The only possible problem with this solution might be (depending on what you want) is that the redirect will only happen if both the beta and gamma query string variables are present in the query string. If they are not, the redirect will not happen.

The redirect rule matches against any URL ((.*)). If needed, you can change that. I've also added an extra condition to not have the rule match against the redirect URL itself which would otherwise cause the redirect URL to be redirected itself.