System.DirectoryServices.Protocols - FastConcurrentBind does not work on linux

[null-d3v]

Description

LdapSessionOptions.FastConcurrentBind() does not work on linux.

Valid or invalid credentials will result in the following:

System.DirectoryServices.Protocols.LdapException: The LDAP server returned an unknown error.
    at System.DirectoryServices.Protocols.ErrorChecking.CheckAndSetLdapError(Int32 error)
    at System.DirectoryServices.Protocols.LdapSessionOptions.FastConcurrentBind()

Sample:

var connection = new LdapConnection(
    new LdapDirectoryIdentifier(
        LdapOptions.Server),
    credential,
    AuthType.Negotiate);

connection.SessionOptions.ProtocolVersion = 3;

userConnection.SessionOptions
    .FastConcurrentBind();

Configuration

• .NET 5.0.0-preview.820414.8
• aspnet:5.0-alpine docker image
• x86_64
• libldap 2.4
• Windows Server 2019 DC

Regression

The exact code is functional when executing from the docker container's Windows host.

[ericstj]

I believe this is known to not work:

runtime/src/libraries/Common/src/Interop/Interop.Ldap.cs

Line 85 in c0b87c7

LDAP_OPT_FAST_CONCURRENT_BIND = 0x41, // Not Supported in Linux

The option doesn't appear to be known by libldap. I think the right place to file this request would be https://github.com/openldap/openldap/.

@joperezr do you agree?