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From Bob DeRemer <bob.dere...@thingworx.com>
Subject RE: solution - RE: how to access HTTP response from jsr-356 ServerEndpointConfig.Configurator.modifyHandshake?
Date Tue, 10 Sep 2013 12:56:26 GMT


> -----Original Message-----
> From: André Warnier [mailto:aw@ice-sa.com]
> Sent: Tuesday, September 10, 2013 6:12 AM
> To: Tomcat Users List
> Subject: Re: solution - RE: how to access HTTP response from jsr-356
> ServerEndpointConfig.Configurator.modifyHandshake?
> 
> Bob DeRemer wrote:
> >
> >> -----Original Message-----
> >> From: Bob DeRemer [mailto:bob.deremer@thingworx.com]
> >> Sent: Monday, September 09, 2013 1:30 PM
> >> To: Tomcat Users List
> >> Subject: RE: how to access HTTP response from jsr-356
> >> ServerEndpointConfig.Configurator.modifyHandshake?
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: Niki Dokovski [mailto:nickytd@gmail.com]
> >>> Sent: Monday, September 09, 2013 1:11 PM
> >>> To: Tomcat Users List
> >>> Subject: Re: how to access HTTP response from jsr-356
> >>> ServerEndpointConfig.Configurator.modifyHandshake?
> >>>
> >>> On Mon, Sep 9, 2013 at 5:26 PM, Bob DeRemer
> >>> <bob.deremer@thingworx.com>wrote:
> >>>
> >>>>  Thanks for the direction on using the respective Client/Server
> >>>> EndpointConfig.Configurator plumbing to do a pre-connection AUTH.
> >>>> Unfortunately, I'm stuck on the server side when trying to actually
> >>>> modify the HTTP response result code from within the Configurator.
> >>>> It doesn't appear that the HandshakeResponse [or anything else that
> >>>> I could see] provides access to modify the actual HTTP response -
> >>>> setting it to
> >>> 403 if
> >>>> the AUTH fails.    In fact, from looking at the UpgradeUtil.doUpgrade,
it
> >>>> seems that the decision to upgrade has already been made by the
> >>>> time the modifyHandshake override gets called.
> >>>>
> >>> Yes the decision is'already made at that point. In this version of
> >>> the spec and current implementation, the only place to actully
> >>> provide different status code (aka 403) is when checkOrigin returns false.
> >>> http://docs.oracle.com/javaee/7/api/javax/websocket/server/ServerEnd
> >>> po
> >>> intC
> >>> onfig.Configurator.html#checkOrigin(java.lang.String)
> >>>
> >>> I don't know wether this works in your case, but for sure the next
> >>> spec revision could try to provide more application control in
> >> "modifyHandshake"
> >> checkOrigin would work if there was some way to gain access to the
> >> client supplied headers.  Is there any way for my checkOrigin method
> >> to get access to the calling request and associated HTTP headers?  If
> >> not, then I'm not sure how to perform a pre-connected AUTH check based
> on the current implementation.
> >>
> >> if there are any other suggestions, please LMK; meanwhile, I'll keep
> >> digging to see if there's another solution.
> >>
> >> Thx,bob
> >>
> >
> > After looking at the options available and going through the websocket
> protocol specification again, I've found a better solution for authenticating
> using a JSR-356 implementation than the original concept of using
> ServerEndpointConfig.Configurator.modifyHandshake.  The new approach still
> uses custom Client and Server EndpointConfig/Configurator instances to pass
> security information during the handshake, but instead of rejecting the
> handshake, it's cleaner to grab the security information in the OnOpen (from
> the ServerEndpointConfig) of the actual endpoint.  At this point, simply perform
> whatever AAA you wish - calling close with an appropriate CloseReason if AAA
> fails.
> >
> > With regard to DOS and opening websocket connections:
> >
> > The websocket protocol already prohibits multiple clients from being in the
> connecting/handshake phase at once, which already helps reduce the DOS
> surface area.  In addition, the client and/or server side implementations can
> add additional logic to prohibit the number of concurrent connections from the
> same client endpoint based on configuration.
> >
> > And, yes, once I get it done and tested, I'll write this up.
> >
> 
> Hi.
> I have been watching this a bit from the outside, and I am neither a Java nor a
> Tomcat nor a websocket expert.
> But I am wondering a bit if we are not here missing the forest for the trees, in
> the following sense :
> If I understand correctly the issue at hand, it would be about
> 1) preventing DoS attacks by "protecting" the websocket interface by a prior
> AAA phase
> 2) how to do this AAA phase
> 
> When I read through the JSR-356, it looks to me more concerned about what
> happens while the websocket connection is actually open, than about what
> precedes it.
> And when I read the websocket RFC-6455, it seems to me that at least in terms
> of the intent, the websocket connection is established - from the server point of
> view - when the server returns a 101 response status. And anything before that
> is part of the "initial handshake", which as far as I understand it is purely HTTP
> and includes anything to do with AAA.
> 
> See RFC-6455 :
> 
> 4.  Opening Handshake
> 4.1.  Client Requirements
> ...
>     12.  The request MAY include any other header fields, for example,
>          cookies [RFC6265] and/or authentication-related header fields
>          such as the |Authorization| header field [RFC2616], which are
>          processed according to documents that define them.
> 
>     Once the client's opening handshake has been sent, the client MUST
>     wait for a response from the server before sending any further data.
>     The client MUST validate the server's response as follows:
> 
>     1.  If the status code received from the server is not 101, the
>         client handles the response per HTTP [RFC2616] procedures.  In
>         particular, the client might perform authentication if it
>         receives a 401 status code; the server might redirect the client
>         using a 3xx status code (but clients are not required to follow
>         them), etc.  Otherwise, proceed as follows.
> 
> ...
> 
> In JSR-356, there is similarly :
> 
> 8.1 Authentication of Websockets
> This specification does not define a mechanism by which websockets
> themselves can be authenticated.  Rather, by building on the servlet defined
> security mechanism, a websocket that requires authentication must rely on the
> opening handshake request that seeks to initiate a connection to be previously
> authenticated. Typically, this will be performed by a Http authentication
> (perhaps basic or form-based) in the web application containing the websocket
> prior to the opening handshake to the websocket.
> 
> In other words, I am a bit confused as to why there would need to be a need for
> any websocket application to be able to either access the client-sent
> authentication headers, cookies etc.., or why it should be possible to the
> websocket application to trigger the sending of a HTTP 4xx response.
> 
> This should all already have happened at the initial HTTP handshake phase, and
> should not be a concern for the websocket interface itself.  It may be nice for
> the websocket application later on to have read access to the (or some)
> headers sent by the client during the initial handshake, but this does not look
> like a requirement.
> 
> Or am I in turn missing something ?
> 

Hi Andre,

I see what you mean and believe using an HTTP-based auth approach may work in some scenarios.
 I'm not sure if this would work in one of our primary scenarios, which is dealing with many
real-world devices that do not have a UI, so basic/form authentication isn't an option.  That
said, I will have to see if I can use a standard Filter approach in front of our websocket
endpoints.  If I can programmatically add an auth filter, then I may be able to perform the
auth check in the same manner as we do for our stand HTTP-based REST api.

Thx, bob
> 
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