Re: [regext] Comments to the feedback about epp-over-http

[Mario Loffredo <[e-mail]>]

Hi James,

thanks for ypur quick reply.

Please find my comments below.

Il 25/03/2022 16:45, Gould, James ha scritto:
>
> Mario,
>
> For #4 “Cookie vs. HTTP Connection”, you asked the question “can you 
> further clarify why we should opt for establishing the cookie at setup 
> of the connection and how should it be possible? For example, what 
> kind of request should be used to start the HTTP connection?”.
>
> I implemented pluggable transports in the Verisign EPP SDK, which 
> included HTTP, HTTPS, TCP, and TLS. The Verisign EPP SDK does include 
> a client interface as well as a server stub implementation, so I was 
> able to see the transports from both sides.  Support for HTTP and 
> HTTPS was removed once we stopped supporting EPP over HTTP.  The 
> cookie is setup at the time of the HTTP or HTTPS connection.  There is 
> no “request” that is used to start the HTTP connection, just like the 
> case for TCP and TLS.  A network connection is made, which includes 
> the underlying TLS handshake in the case of HTTPS and TLS and the 
> cookie is setup for HTTP and HTTPS, and then the EPP application 
> protocol rides on top of it.
>
It seems to me a very low-level implementation.

Sorry but I stiil don't understand how cookies are returned. They should 
be returned in an HTTP response that doesn't correspond to an HTTP 
request. Correct?

If so, it seems to me uncompliant with what is stated in the first 
paragraph of Section 2.1 of RFC7230:

    HTTP is a stateless request/response protocol that operates by
    exchanging messages (Section 3  <https://www.rfc-editor.org/rfc/rfc7230#section-3>) across a reliable transport- or
    session-layer "connection" (Section 6  <https://www.rfc-editor.org/rfc/rfc7230#section-6>).*An HTTP "client" is a program that establishes a connection to a server 
for the purpose of sending one or more HTTP requests.*   *An HTTP "server" is a program that accepts connections in order to 
service HTTP requests by sending HTTP responses.*

Anyway, the approach normally followed by every HTTP implementer 
leverages the services provided by an application server that 
incorporates an HTTP server.

You don't need to manage HTTP connections, HTTP resquest/response 
marhsalling/unmarshalling and other low-level details. You just need to 
focus on the core of your server.

Similarly, on the other side side, after having configured an HTTP 
client instance, a client simply builds and sends an HTTP request, and  
then receives and processes an HTTP response.

> If there is a HTTP transport for EPP, then it should be purely a 
> transport and not intermingle with the application protocol.  There is 
> no need to directly tie a HTTP session with the established EPP 
> session.  By keeping them separate, it makes it much easier for the 
> client and the server to have pluggable transports, where the 
> processing of the EPP commands including the hello, login, and logout 
> treat the transport as simply a connection with no intermingling of 
> session management.
>
If it means that you have to reimplement what has commonly been used for 
years, it isn't clear to me how it could be much easier. On the 
contrary, it seems to me much trickier, especially if you implement 
EPP-over-HTTP from scratch.

If the goal is using the same approach for mapping every transport layer 
without considering the peculiarites of each transport protocol and the 
technology the implementers are accostumed to use to deal with them, it 
doesn't make sense to me.

For example, I cannot figure out how HTTP load balancing could support 
your solution.


Best,

Mario

> -- 
>
> JG
>
>
>
>
> *James Gould
> *Fellow Engineer
> [e-mail] 
> <applewebdata://13890C55-AAE8-4BF3-A6CE-B4BA42740803/[e-mail]>
>
> 703-948-3271
> 12061 Bluemont Way
> Reston, VA 20190
>
> Verisign.com <http://verisigninc.com/>
>
> *From: *regext <[e-mail]> on behalf of Mario Loffredo 
> <[e-mail]>
> *Date: *Friday, March 25, 2022 at 11:01 AM
> *To: *"[e-mail]" <[e-mail]>
> *Subject: *[EXTERNAL] [regext] Comments to the feedback about 
> epp-over-http
>
> Hi folks,
>
> here are in the following some comments grouped by subject to last 
> meeting's feedback about EPP-over-HTTP:
>
> *1) Draft title*
>
> Ulrich suggested to call the document EPP-over-HTTPS.
>
> I replied that the name was assigned to be consistent with RFC5734, 
> i.e. EPP-over-TCP.
>
> SImilarly to RFC5734, the draft states, first in the abstract and then 
> in the security considerations, that TLS is required.
>
> That being said, the authors don't object to renaming the dcocument 
> EPP-over-HTTPS if the WG agrees.
>
> *2)  Cookies*
>
> Jim (Reed) asked why cookies should be used in this case.
>
> The reasons why we have used session cookiea are that they represent a 
> standard method (RFC6265), well known to the community of REST service 
> implementers, largely used and natively supported by libraries and 
> frameworks on both client and server side. For example, it is the same 
> method used by rdap-openid to map an RDAP session and tie it to an 
> access token :-)
>
> .it and .pl have been using this method since the beginning and the 
> registrars, after being informed that they had to enable cookies in 
> their HTTP clients, have no longer complained about cookie management.
>
> In addition, the implementation of such a method doesn't  introduce 
> any change to the EPP core spec. Indeed, it preserves EPP comands 
> semantics and doesn't mix the application layer with the transport layer.
>
> I would like to say that, regarding the clear distinction between 
> those layers, this proposal is even better than RFC5734 as every EPP 
> response is returned by the server as a consequence of receiving an 
> EPP request.
>
> On the contrary, in RFC5734, an EPP <greeting> is returned to the 
> client after the TCP connection has been established so, at least in 
> this case, the**two layers get mixed.
>
> Which method other than session cookie shoud be used instead ?
>
> *3)   Security Considerations*
>
> Ulirch recommended to review the security considerations by inheriting 
> those from TLS WG about which versions and ciphers of TLS to use.
>
> Thanks a lot for the heads up, Ulrich. Surely, we'll do.
>
> Gavin noted that, unlike EPP-over-TCP, this draft states that client 
> IP address check is optional.
>
> As a matter of fact, it is stated as recommended.
>
> Anyway, the authors don't object to changing it into an absolute 
> rquirement if the WG agrees.
>
> *4)  Cookie vs. HTTP Connection*
>
> One comment from James in the chat is about establishing the cookie at 
> setup of the connection and not linking it to the EPP Login command.
>
> James, can you further clarify why we should opt for establishing the 
> cookie at setup of the connection and how shoudl it be possible? For 
> example, what kind of request should be used to start the HTTP connection?
>
> IMO, an HTTP session is something that is inherently unlinked to the 
> HTTP connections.
>
> HTTP connections can be broken but sessions don't get lost.
>
> Programmatically, REST implementers are in charge of processing HTTP 
> requests and building responses rather than managing HTTP connections, 
> which is instead delegated to the application servers.
>
> Finally, I would like to outline that Section 2.9.1 of RFC5730 states 
> that an EPP session starts with a Login command and the mechanism 
> described by RFC6265 lets (I'm quoting here) "the servers maintain a 
> stateful session over the mostly stateless HTTP protocol". As a 
> consequence, it seems much more practical to start the EPP/HTTP 
> session as a result of a Login command.
>
> *5) EPP/HTTP Sessions vs. HTTP3 Connections*
>
> Ulrich remarked that, in HTTP3, it is possible to have multiple 
> sessions on an HTTP connection.
>
> This is valid also for the other HTTP versions.
>
> In fact, an HTTP connection can be kept alive and, over it, a client 
> could submit multiple login-commands-logout sequences.
>
> This is quite usual for a smart client managing a pool of HTTP 
> connections.
>
> Instead, It is unlikely but not impossible to come across HTTP 
> connections supporting multiple concurrent sessions.
>
> What should be the possible drawbacks for a server in allowing the 
> scenarios above?
>
> *6) Client authentication in HTTP3*
>
> Another note pointed out that HTTP3 client authentication requirements 
> are different from this draft and they need to be reconciled.
>
> Think that it could be sufficient to add to the security 
> considerations some text similar to what is included in section 4.4 
> "Peer authentication" of RFC 9001 "Using TLS to secure QUIC":
>
>     A client MUST authenticate the identity of the server.  This
>     typically involves verification that the identity of the server is
>     included in a certificate and that the certificate is issued by a
>     trusted entity (see for example [RFC2818  <https://secure-web.cisco.com/1tkPqD6aAMfTp6t6KppHDGdn0xpgOWSMeCqwZR-hs9Duph9SiceA0vCbaJJVqywNzcZscc6vUZkCPH9lCdtXq_nVJ3OfnNMz-XTQvhBuSBLsXa0VfO5ZNrGo47fSin8GRaQOWRSvSQP_7vRecBdddhF6L0Yqx3KcxAGpvdxpFCsPhLcd5bm-aVy3vTko6TfGBlohe2XEw3bwUmH-u56ZuZz50CUXUqA3YDFgBENAwPrLBjwdDxwgG1JFVGPZF_LEQ/https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc2818>]).
>
> The draft has only considered the optional use of a certificate on 
> server side (not on client side). In doing that, the draft is 
> consistent with another sentence in the same paragraph of RFC9001:
>
>     A server MAY request that the client authenticate during the
>     handshake.  A server MAY refuse a connection if the client is unable
>     to authenticate when requested.
>
> Would it address the feedback?
>
> That's all for now.
>
> Hope I did not miss anything.
>
> Thanks a lot for your interest and feedback.
>
> Looking forward to your further comments.
>
> Best,
>
> Mario
>
> -- 
> Dr. Mario Loffredo
> Technological Unit “Digital Innovation”
> Institute of Informatics and Telematics (IIT)
> National Research Council (CNR)
> via G. Moruzzi 1, I-56124 PISA, Italy
> Phone: [phone]
> Web:http://www.iit.cnr.it/mario.loffredo  <http://secure-web.cisco.com/1Af0lIvD4wj2TkngfEVwrFVEVRozLiVIU2m1Gi1AH1GN4-eWP-IREXsOLCh8OJ03YAxRNYqVCPHQSwgj-tMCyzvN3jokOBTIBx4-5n1pJdiRXxl-ShJCaHkCjGNPa8EA5qw4kPjkxIrFAy1qOTcPFhieqdc_xyu8yisYoXzily9ozVw3GZaUtkKrLnmnDJhlFv2LRTCTnw913LzH8bX-hB6FpPlyFi_0v2_H1NFCgZYjuu4pgUeOeIqQJRQwtzNLS/http%3A%2F%2Fwww.iit.cnr.it%2Fmario.loffredo>

-- 
Dr. Mario Loffredo
Technological Unit “Digital Innovation”
Institute of Informatics and Telematics (IIT)
National Research Council (CNR)
via G. Moruzzi 1, I-56124 PISA, Italy
Phone: [phone]
Web:http://www.iit.cnr.it/mario.loffredo