WCF FaultCode MustUnderstand = 1 .net 4.0 - wcf

Question

How do I change my wcf service to be able to accept mustunderstand = 1?
This is a scenario where I have to change the service to be able to accept a request from the client. The client sends mustunderstand =1 in the header.
The service is configured to use basichttpBinding
<security mode="TransportWithMessageCredential">
<message clientCredentialType="UserName"/>
<transport clientCredentialType="None"></transport>
</security>
Using soap UI I insert the following username token into the header
<wsse:Security soapenv:mustUnderstand="1" xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<wsse:UsernameToken wsu:Id="UsernameToken-2684C13EA73A35131015516775308851">
<wsse:Username>username</wsse:Username>
<wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">password</wsse:Password>
</wsse:UsernameToken>
</wsse:Security>
I can reproduce the issue on soap UI when I insert this token in the wcf service request. This is the error
<FaultMsgRec>
<ErrCode>100</ErrCode>
<ErrCat>Error</ErrCat>
<ErrDesc>An unsecured or incorrectly secured fault was received from the other party. See the inner FaultException for the fault code and detail.--> The header 'Security' from the namespace 'http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd' was not understood by the recipient of this message, causing the message to not be processed. This error typically indicates that the sender of this message has enabled a communication protocol that the receiver cannot process. Please ensure that the configuration of the client's binding is consistent with the service's binding. </ErrDesc>
</FaultMsgRec>
Since I have control over the wcf service I can go and add ValidateMustUnderstand = false in the service behavior.
Just like it is explained in the link
https://learn.microsoft.com/en-us/dotnet/api/system.servicemodel.description.mustunderstandbehavior.validatemustunderstand?view=netframework-4.7.2
Once I add this to the service behavior the error disappears.
But I don't want to turn off validation on the header especially if its a username, password. What should I do to allow mustunderstand=1? Am I missing something that the service doesn't automatically process mustunderstand=1 by default. I know there is code to be written on the client in order to sent a 0 in the header.
I am using message contracts in my wcf service not data contract. I understand that for certain properties I can go and add attributes like this link
https://learn.microsoft.com/en-us/dotnet/api/system.servicemodel.messageheaderattribute.mustunderstand?view=netframework-4.7.2. But I am not adding to any properties. I am just adding it to the first linke in soapenv:mustunderstand=1
Please help!.
Thank you

Answer 1

Not sure whether this could solve your problem. But you could try to add your header in web.config.
<endpoint address="http://ws-wuxipc-5077:4000/calculator" binding="basicHttpBinding"
contract="ServiceInterface.ICalculatorService" name="cal">
<headers>
<Security xmlns="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" >
<wsse:UsernameToken xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<wsse:Username>
</wsse:Username>
<wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordDigest">monMonDePasse</wsse:Password>
<wsse:Nonce>sdsdsdlojhfdsdM5Nw==</wsse:Nonce>
<wsu:Created>2019-01-21T6:17:34Z</wsu:Created>
</wsse:UsernameToken>
</Security>
</headers>
</endpoint>
Or you could add header using code.
using (ChannelFactory<ICalculatorService> ChannelFactory = new ChannelFactory<ICalculatorService>("cal"))
{
ICalculatorService employeeService = ChannelFactory.CreateChannel();
using (OperationContextScope scope = new OperationContextScope((IContextChannel)employeeService))
{
System.Xml.XmlDocument document = new XmlDocument();
XmlElement element = document.CreateElement("wsse", "UsernameToken", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
XmlElement newChild = null;
newChild = document.CreateElement("wsse", "Username", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
newChild.InnerText = "finance";
element.AppendChild(newChild);
newChild = document.CreateElement("wsse", "password", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
newChild.SetAttribute("Type", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordDigest");
newChild.InnerText = "387";
element.AppendChild(newChild);
MessageHeader messageHeader = MessageHeader.CreateHeader("security", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd", element, false); // here is mustunderstood is set to false
OperationContext.Current.OutgoingMessageHeaders.Add(messageHeader);
}
Console.Read();
}