DotNetNuke 4 Custom Authentication / Single Sign On

Updated on 8/12/2008 — It has come to my attention this solution stopped working with DotNetNuke 4.8. I believe it should work with 4.5 – 4.7. I don’t work with DNN anymore so I probably can’t be very helpful, but if someone else has written a newer post on the topic, I’d be happy to link there.

—

So I’ve been working with DotNetNuke as our portal solution at work. My first task was to plug in to the authentication scheme to make it use our existing user database. This seems like a simple request, and in the end it was.

My big problem was the lack of documentation. First of all there is very little experience out there with DNN4. Secondly, the other providers of SSO are either commercial or very confusing, especially for a Java-turned-C# developer like myself. So I thought I’d lay it out, because it’s not very hard.

First of all, I didn’t want to completely gut the entire system, because DNN provides a lot of nice role management stuff interally. So what I did was to write a go-between that transparantly creates DNN accounts if you can authenticate to our existing user database. I wrote a new Membership Provider that extends the AspNetMembershipProvider. Heres some code:

[csharp]
class MembershipProvider : AspNetMembershipProvider
{
public MembershipProvider(): base(){}

override public UserInfo UserLogin(int portalId, string username,
string password, string verificationCode,
ref UserLoginStatus loginStatus)
{
if (password == “!EXTERNAL_AUTH!”)
{ //protect the reserved word
loginStatus = UserLoginStatus.LOGIN_FAILURE;
return null;
}

//Ok first up if you can log into the portal that’s good enough for me
UserInfo dnnUser = base.UserLogin(portalId, username, password,
verificationCode, ref loginStatus);
log.Debug(“DNN Login status = ” + loginStatus.ToString() );
if ( loginStatus == UserLoginStatus.LOGIN_SUCCESS ||
loginStatus == UserLoginStatus.LOGIN_SUPERUSER )
return dnnUser;

//This user doesn’t exist in DNN
User u = null;
try
{
u = Internal.Login.Function(session, username, password);
}
catch (Exception ex)
{
log.Info(ex.StackTrace);
loginStatus = UserLoginStatus.LOGIN_FAILURE;
return null; //I hope this works.
}

//If we get here with no exception, the user is valid in the external database
//So try to log them in using the fake password
dnnUser = base.UserLogin(portalId, username, “!EXTERNAL_AUTH!”,
verificationCode, ref loginStatus);
if ( loginStatus == UserLoginStatus.LOGIN_SUCCESS ||
loginStatus == UserLoginStatus.LOGIN_SUPERUSER )
return dnnUser;

//Not in the DB, make a new user since they are authenticated
UserInfo newUser = new UserInfo();
newUser.DisplayName = “New User”;
newUser.Email = “email”;
newUser.PortalID = portalId;
newUser.Username = username;
newUser.IsSuperUser = false;
//This is an important part to be sure the user has our special password
UserMembership um = new UserMembership();
um.Password = “!EXTERNAL_AUTH!”;
um.Approved = true;
um.Username = username;
newUser.Membership = um;
base.CreateUser(ref newUser);
newUser.FirstName = “Unknown”;
newUser.LastName = “Unknown”;
base.UpdateUser(newUser);
//Try to log them in again
dnnUser = base.UserLogin(portalId, username, “!EXTERNAL_AUTH!”,
verificationCode, ref loginStatus);
if (loginStatus == UserLoginStatus.LOGIN_SUCCESS ||
loginStatus == UserLoginStatus.LOGIN_SUPERUSER)
return dnnUser;

throw new Exception(“FATAL: Unknown error mapping external login to DNN”);
}
}
[/csharp]

Then change the web.config to use your new MembershipProvider instead of the AspNetMembershipProvider. That’s really all there is to it.

It probably also wouldn’t be a bad idea to override some of the other functions like ChangePassword, DeleteUser, CreateUser, etc. depending on your situation.