eap Mailing List: Re: Re: Issue 281: Backward compatibility problem

[Jari Arkko (jari.arkko]

Bernard, Farid,

> > 2) Modify the grammar to allow the NAIRealms to be placed 
> >    anywhere after displayable message.
>
> I'd prefer this.  It's more consistent with RFC 3748, as well 
> as existing implementations.

I would prefer #2 as well.

> identity-request-data = [ displayable-string ] %0x00 [ Network-Info ]   
>
> displayable-string    = *CHAR
>
> Network-Info          = *OCTET ["," "NAIRealms=" realm-list "," ] *OCTET

The general approach is correct, but I'd prefer making the
NAIRealms data start with either directly after the NUL character
or after a comma -- not always with a comma. How about this:

Network-Info     =   "NAIRealms=" realm-list
Network-Info     =/  1*OCTET ",NAIRealms=" realm-list
Network-Info     =/  "NAIRealms=" realm-list "," 1*OCTET
Network-Info     =/  1*OCTET ",NAIRealms=" realm-list "," 1*OCTET

Note that this still allows multiple %0x00's to be present
at various places. For instance, the following would all be
legal

    foo\0NAIRealms=snaap.com
    bar\0NAIRealms=fryyp.com\0\0\0\0
    foobar\0\0\0\0,NAIRealms=example.com
    \0APQuality=0,NAIRealms=arkko.com

> realm-list            = realm /
>                         ( realm-list ";" realm )
>
> The "OCTET" and "CHAR" rules are defined in [RFC2234] and the "realm"
> rule is defined in [rfc2486bis].
>
> A sample hex dump of an EAP-Request/Identity packet is shown below.
>
>       01                        ; Code: Request
>       00                        ; Identifier: 0
>       00 43                     ; Length: 67 octets
>       01                        ; Type: Identity
>       48 65 6c 6c 6f 00 2C 4e   ; "Hello\0,NAIRealms=example.com;mnc014.
>       41 49 52 65 61 6c 6d 73   ; mcc310.3gppnetwork.org,"
>       3d 69 73 70 2e 65 78 61
>       6d 70 6c 65 2e 63 6f 6d
>       3b 6d 6e 63 30 31 34 2e
>       6d 63 63 33 31 30 2e 33
>       67 70 70 6e 65 74 77 6f
>       72 6b 2e 6f 72 67 2C

Ok otherwise but I'd prefer getting rid of the "," after
"\0".

> The Network-Info can contain NAIRealms list in addition to proprietary
> information. The proprietary information can be placed before or after
> NAIRealms list.  To extract NAIRelams list, an implementation can parse
> the data after a NUL and look for "NAIRealms=" and then check whether
> the previous character was a comma.  Once "NAIRealms=" immediately
> followed by a comma is found, the implementation can read the realms
> until it encounters a comma character.

Slightly revised:

  The Network-Info can contain NAIRealms list in addition to proprietary
  information. The proprietary information can be placed before or after
  NAIRealms list.  To extract NAIRelams list, an implementation either
  finds the "NAIRealms=" immediately after the NUL or seeks forward to
  find ",NAIRealms" somewhere in the string. The realms data ends either
  at first "," or at the end of the string, whichever comes first.

--Jari