rspec/rules/S5766/csharp/rule.adoc

include::../description.adoc[]

include::../ask-yourself.adoc[]

include::../recommended.adoc[]

== Sensitive Code Example

When a ``++serializable++`` class doesn't inherit from https://docs.microsoft.com/en-us/dotnet/api/system.runtime.serialization.iserializable?view=netframework-4.8[ISerializable] or https://docs.microsoft.com/fr-fr/dotnet/api/system.runtime.serialization.ideserializationcallback?view=netframework-4.8[IDeserializationCallback] types and has a constructor using its parameters in conditions:

----
[Serializable]
public class InternalUrl
{
    private string url;

    public InternalUrl(string tmpUrl) // Sensitive
    {       
       if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
       {
          url= "http://localhost/default";
       }
       else
       {
          url= tmpUrl;
       }
    }
}
----

When a class inherit from https://docs.microsoft.com/en-us/dotnet/api/system.runtime.serialization.iserializable?view=netframework-4.8[ISerializable] type, has a regular constructor using its parameters in conditions, but doesn't perform the same validation after deserialization:

----
[Serializable]
public class InternalUrl : ISerializable
{
    private string url;

    public InternalUrl(string tmpUrl) // Sensitive
    {
        if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
        {
            url= "http://localhost/default";
        }
        else 
        {
            url= tmpUrl;
        }
    }

    // special constructor used during deserialization
    protected InternalUrl(SerializationInfo info, StreamingContext context) // Sensitive
    {
       url= (string) info.GetValue("url", typeof(string));
       // the same validation as seen in the regular constructor is not performed
     }

    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
    {
        info.AddValue("url", url);
    }
}
----

When a class inherit from https://docs.microsoft.com/fr-fr/dotnet/api/system.runtime.serialization.ideserializationcallback?view=netframework-4.8[IDeserializationCallback] type, has a constructor using its parameters in conditions but the ``++IDeserializationCallback.OnDeserialization++`` method doesn't perform any conditional checks:

----
[Serializable]
public class InternalUrl : IDeserializationCallback
{
    private string url;

    public InternalUrl(string tmpUrl) // Sensitive
    {
        if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
        { 
            url= "http://localhost/default";
        }
        else 
        {
            url= tmpUrl;
        }
    }

    void IDeserializationCallback.OnDeserialization(object sender) // Sensitive
    {
       // the same validation as seen in the constructor is not performed
    }
}
----

== Compliant Solution

When using https://docs.microsoft.com/en-us/dotnet/api/system.runtime.serialization.iserializable?view=netframework-4.8[ISerializable] type to control deserialization, perform the same checks inside regular constructors than in the special constructor ``++SerializationInfo info, StreamingContext context++`` used during deserialization:

----
[Serializable]
public class InternalUrl : ISerializable
{
    private string url;

    public InternalUrl(string tmpUrl)
    {
        if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
        {
            url= "http://localhost/default";
        }
        else 
        {
            url= tmpUrl;
        }
    }

    // special constructor used during deserialization
    protected InternalUrl(SerializationInfo info, StreamingContext context)
    {
       string tmpUrl= (string) info.GetValue("url", typeof(string));

       if(!tmpUrl.StartsWith("http://localhost/") { // Compliant
          url= "http://localhost/default";
       }
       else {
          url= tmpUrl;
       }
     }

    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
    {
        info.AddValue("url", url);
    }
}
----

When using https://docs.microsoft.com/fr-fr/dotnet/api/system.runtime.serialization.ideserializationcallback?view=netframework-4.8[IDeserializationCallback] type to control deserialization, perform the same checks inside regular constructors than after deserialization with ``++IDeserializationCallback.OnDeserialization++`` method:

----
[Serializable]
public class InternalUrl : IDeserializationCallback
{
    private string url;

    public InternalUrl(string tmpUrl)
    {
       if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
       {
          url= "http://localhost/default";
       }
       else
       {
          url= tmpUrl;
       }
    }

    void IDeserializationCallback.OnDeserialization(object sender) // Compliant
    {
        if(!url.StartsWith("http://localhost/"))
        {
            url= "http://localhost/default";
        }
        else 
        {
        }
    }
}
----

include::../see.adoc[]