Disable CustomUserNamePasswordValidator for specific operation - wcf

Question

I am using a CustomUserNamePasswordValidator for my WCF web service. However, i am trying to add a IsAlive operation, which should be able to be called from clients, even when not authenticated.
For example, i want to be able to do a check, if a service is online and accessible on startup, so i can notify the user on missing inet connection or a not available service (due to maintenance).
I have code for all this already in place. What i am missing is how i can access the operation without passing a username and password.
I could probably just add a second service which allows anon access, but i'd really prefer to use the existing service.
The Validator is implemented like this (i ommited the actual checking code):
public sealed class MyCredentialValidator : UserNamePasswordValidator
{
public MyCredentialValidator ()
{
}
public override void Validate(string userName, string password)
{
Debug.WriteLine("MyCredentialValidator : Validate called.");
// do some checks
var isValid = CheckCredentials(userName, password)
if(!isValid)
{
throw new FaultException(...);
}
}
}
It is registered in the web.config like so:
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior name="SecureBehavior">
<serviceMetadata httpsGetEnabled="false"/>
<serviceDebug includeExceptionDetailInFaults="true"/>
<serviceCredentials>
<userNameAuthentication userNamePasswordValidationMode="Custom" customUserNamePasswordValidatorType="MyCredentialValidator,..."/>
</serviceCredentials>
</behavior>
</serviceBehaviors>
</behaviors>
<serviceHostingEnvironment multipleSiteBindingsEnabled="true"/>
<bindings>
<wsHttpBinding>
<binding name="SecureBinding" closeTimeout="00:10:00" openTimeout="00:10:00" receiveTimeout="00:10:00" sendTimeout="00:10:00" maxReceivedMessageSize="2147483647">
<security mode="TransportWithMessageCredential">
<message clientCredentialType="UserName"/>
</security>
<readerQuotas maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxStringContentLength="2147483647"/>
</binding>
</wsHttpBinding>
</bindings>
<services>
<service name="my service" behaviorConfiguration="SecureBehavior">
<endpoint address="" binding="wsHttpBinding" contract="my contract" bindingConfiguration="SecureBinding">
<identity>
<dns value="localhost"/>
</identity>
</endpoint>
<endpoint address="mex" binding="mexHttpsBinding" contract="IMetadataExchange"/>
</service>
</services>
</system.serviceModel>
client side configuration:
<system.serviceModel>
<bindings>
<wsHttpBinding>
<binding name="SecureBinding"
closeTimeout="00:10:00"
openTimeout="00:10:00"
receiveTimeout="00:10:00"
sendTimeout="00:10:00"
maxReceivedMessageSize="2147483647">
<security mode="TransportWithMessageCredential">
<message clientCredentialType="UserName"/>
</security>
<readerQuotas maxArrayLength="2147483647"
maxBytesPerRead="2147483647"
maxStringContentLength="2147483647"/>
</binding>
</wsHttpBinding>
</bindings>
<client>
<endpoint address="https://my service url"
contract="my contract"
binding="wsHttpBinding"
bindingConfiguration="SecureBinding"
name="secure" />
</client>
</system.serviceModel>
client side wcf call code:
var cf = new ChannelFactory<my contract>("secure");
using (IClientChannel channel = (IClientChannel)cf.CreateChannel())
{
channel.OperationTimeout = TimeSpan.FromSeconds(3);
bool success = false;
try
{
channel.Open();
result = ((my contract)channel).IsAlive();
channel.Close();
success = true;
}
finally
{
if (!success)
{
channel.Abort();
}
}
}

Answer 1

I have done something like this before,
depending on how you have integrated your custom validator in the wcf pipleline,
you could simply before you do the actual validation, which I guess returns something like true or false, you could check the incoming url or address and see if it is going to be going to your IsAlive operation, if that is the case, you could simply do a early return true.
Wcf has a few ways with which you can check what operation the client has called.
to be more accurate, I would need to know how you wrote your custom validator and where in the pipeline it integrates.