On 28.10.2015 17:42, Torsten Rieger wrote:
-----Ursprüngliche Nachricht-----
Von: Aurélien Terrestris [mailto:aterrest...@gmail.com]
Gesendet: Mittwoch, 28. Oktober 2015 16:45
An: Tomcat Users List <users@tomcat.apache.org>
Betreff: Re: AW: Suppress or replace WWW-Authorization header

You can choose between a pop-up or an HTML FORM

This one looks like this in web.xml :

   <login-config>
     <auth-method>FORM</auth-method>
     <realm-name>webapp global realm</realm-name>
     <form-login-config>
       <form-login-page>/login.jsp</form-login-page>
       <form-error-page>/error_login.jsp</form-error-page>
     </form-login-config>
   </login-config>




2015-10-28 16:28 GMT+01:00 Torsten Rieger <torsten.rie...@promatis.de>:

-----Ursprüngliche Nachricht-----
Von: Christopher Schultz [mailto:ch...@christopherschultz.net]
Gesendet: Mittwoch, 28. Oktober 2015 15:39
An: Tomcat Users List <users@tomcat.apache.org>
Betreff: Re: AW: Suppress or replace WWW-Authorization header

Torsten,

On 10/28/15 8:19 AM, Torsten Rieger wrote:
I have a legacy java-SOAP-client that only supports BASIC
authentication (send the Authorization: Basic... header) and a
AngularJS application that consumes a REST-service (also sending the
Authorization: Basic header).

The server supports two kinds of deployment: Standalone with an
embedded Jetty-server and as war-file for app-servers (most of them
are tomcat-server). I try to suppress the browser BASIC-login-dialog
for the REST-service-calls from AngularJS.
On Jetty I modify the 401-responses and replace the "WWW-Authenticate"
header by anything else than "BASIC" and that works, now I try to
find a solution for the deployment on tomcat servers.

Rewrite (unset header in responses) with an apache proxy in front of
the tomcat is unfortunately not a solution I can implement.

So I'm looking for a solution to remove or modify the headers in 401
responses on application server level.

So you just want to disable HTTP BASIC authentication? Why not just
remove the <auth-method> from web.xml and disable authentication entirely?

Are you saying that when you connect using a REST client, the client
shows a login dialog in a web browser? That sounds ... weird. The REST
client should see the WWW-Authenticate header and either (a) fail or
(b) re-try with credentials you have provided to it.

-chris

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No, container BASIC authentication should be enabled, the container
should handle the authentication, but the browser should not show his
ugly default login dialog when I request resources from the
REST-service with wrong credentials.
When the REST-client (web-application in the browser) receives a
failed login with a WWW-Authenticate header, the default dialog of the
browser will be shown... that’s what I want to suppress.

When I remove the (a) <login-config> or (b) <auth-method>  sending
requests with credentials will not work anymore (a: 403 forbidden; b:
deployment fails). But that's not a solution because the rest-service
should be still protected and I need to authenticate via "Authentication:
Basic ....."
header send credentials, but I don't want to show the ugly
browser-dialog to the users.

Using a AngularJS Client with REST-services based on tomcat should be
a common use-case, it could not be that I'm the first one who wants a
custom login-screen. :-/

-torsten



The Problem is then, that login via "Authorization: BASIC xyz==" will not
work anymore... the legacy client is not able to handle FORM based login :-/


Torsten, let me try again another way :

1)
>> Using a AngularJS Client with REST-services based on tomcat should be
>> a common use-case, it could not be that I'm the first one who wants a
>> custom login-screen. :-/

No, you probably are not.  But *this has nothing to do with Tomcat per se*.
Any other webserver, in the same circumstances, would send a 401 back, with a request for HTTP Basic authentication. If, at the server level, you configure that for this application, you want HTTP Basic authentication, then that is what you will get. It is not a choice of the server, it is something *imposed* by the HTTP protocol.

If you want something else to happen, but still have the client be authenticated for that application, then you have to change the authentication method required, at the server level. No way around it.

2) If the browser receives a 401 response header which indicates that the requested authentication method should be HTTP Basic, then it will popup its bultin HTTP Basic authentication popup dialog. There is no easy way around this either, because this behaviour is built-in into the code of all major browsers.
(Also because the HTTP protocol says that this is what the browser should do).
If you want this to be different, then you have to find a way to modify the browser-side logic, so that it does not do that. Doing this is possible, but not easy (see some of the other responses), and if not done correctly, it will be buggy and/or introduce security issues.

3) all the responses which I have seen so far on this thread, are technically correct considering the information which you have provided as to what you would like, and what your client-side application can/cannot do. But maybe here, we were all seeing the tree that you put in front of us, and for that reason not seeing the forest behind it.

4) Setting the server-side to do authentication in a different way than HTTP Basic, does not necessarily mean that your application cannot, overall, be authenticated.

The REST application on the server, presumably, does not care *how* the user is authenticated. It just wants an authenticated user, no matter how that happens. It gets the user-id from Tomcat (via request.getUser() or similar), *after* Tomcat has taken care of the authentication. The way in which Tomcat obtains this user-id is not the concern of the application. (At least, that is what a well-behaved application would do).

5) So let's do the authentication in another way, so that the client never even sees a 401 response from the server, and thus never pops up this dialog that you do not want to see.

At the server level, use the form-based authentication, like another poster here already suggested.
What would happen then is as follows :

a) the browser sends a first request to the REST app, un-authenticated.
b) the server sees that this is not authenticated, and sends back to the browser, a login form. Note that this is just a html page, that has nothing to do with the client-side application. (Note : you create this login form, and save it on the server. You just need to tell the server (in the web.xml of the REST application) where this login form is.)
c) the human client fills-in the login form, and his browser posts it back to 
the server.
This goes to another URL on the server (e.g. "/login"), that is *not* the REST 
application.
d) on the server, the login application at "/login" authenticates the user and creates a session, where this authenticated user-id is stored. It also sets the authenticated user-id in the Tomcat request structure, for later usage. The login application also prepares a "session-id" cookie, to be sent back to the browser (later), which points to this saved session on the server. e) The login application now redirects the browser, to the original URL that it was requesting, before all this authentication stuff took place.
That is the REST application.
f) now the REST application gets called, and it can retrieve the user-id from Tomcat, as promised. So it does its work, and sends back the response to the browser.
(Notice that there has never been a 401 response so far)
g) the browser gets the 1st response from the REST application. It also gets, at the same time, the session-id cookie that was added by the authentication part. h) if the browser now sends a second request to the REST application, this session-id cookie will be re-sent to the server also. i) the server now gets the new request, and the cookie. The server uses the cookie to retrieve the saved session, including the user-id in it. The server uses this to set the internal Tomcat user-id, and calls the REST application again. j) the REST application starts working, and retrieves the user-id from Tomcat. So it is happy, and sends back the next response. Tomcat takes care that with this next response, the session-id cookie header is sent again to the browser.
k) the browser sends another request to the server. Go to (h) above.

Notice : still no 401 Basic response header anywhere, so no browser-side Basic 
auth popup.
Notice also : the client-side application is never really involved in the authentication. So whatever it supports or not, is not relevant here.

Note that all the above supposes that the client application on the browser side, does not need to know that it is authenticated. But that is normally the case for client-side applications.

Last note : in the a-k explanation above, I have taken some liberties with the intimate details of how things happen on the server. I hope that the purists will forgive this bit of poetic and tutorial license. Hopefully, it should allow Torsten to get going along the right track, instead of pursuing mirages.



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