Subject: [Sip] Case sensitivity of user name - why RFC 3261 is more strict then RFC 2543 [RESEND]

From: Avshalom Houri <[email-masked]>
Date: Fri, 10 Mar 2006 12:49:05 +0200

Unless I am completely missing something I think that it is an important 
issue.
RFC 3261 seem to imply that user name in SIP is case sensitive while email 
and even RFC 2543
do not impose this restriction.
Unless implementations ignore RFC 3261 in this case there may be a usage 
issue.
Most SIP implementations are connected to email systems and users are used 
to write the user name in a free way
without regarding case. When a user put a name in e.g. a dialogue box for 
INVITE I am not sure that we can expect that
the user will match the way that the other user will register in their 
proxy.

Can someone clarify this issue?

Below are excerpts from the relevant RFCs:

RFC 2543 (section 2, page 24) allows for: 

   SIP URLs are case-insensitive, so that for example the two URLs 
   sip:[email-masked] and SIP:[email-masked] are equivalent.  All 
   URL parameters are included when comparing SIP URLs for equality. 

That is RFC 2543 does not care about the case of the user name.

RFC 3261 says in section 19.14: 

   SIP:[email-masked];Transport=udp             (different usernames) 
   sip:[email-masked];Transport=UDP

That is we are having a stricter rules for user name comparison. 

Does anyone remember why it was done? I could not find a reference to this 
in 
the list of changes from RFC 2543 at the end of RFC 3261. 

In email as far as I know user names are NOT case sensitive. RFC 821 only 
says: 

   Commands and replies are not case sensitive.  That is, a command or 
   reply word may be upper case, lower case, or any mixture of upper and 
   lower case.  Note that this is not true of mailbox user names.  For 
   some hosts the user name is case sensitive, and SMTP implementations 
   must take case to preserve the case of user names as they appear in 
   mailbox arguments.  Host names are not case sensitive. 

So for email servers need only to preserve the name casing. 

Thanks
--Avshalom

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---

From: Avshalom Houri <[email-masked]>
Date: Sun, 12 Mar 2006 07:06:23 +0200

The email RFC does not specify if the user name in the email should be 
case sensitive or not but says
that the case should be preserved in order to accommodate hosts where the 
user name is case sensitive.

Current practice in email is that I can write the user name in what case I 

choose and it will reach to the
user.

So what is the current practice in SIP? Do implementations ignore RFC 
3261? I also could not find
anything about backward compatibility to RFC 2543 who says that user names 

are case insensitive.

Thanks
--Avshalom

Avshalom Houri/Haifa/IBM@IBMIL 
10/03/2006 12:49 PM

To
[email-masked]
cc

Subject
[Sip] Case sensitivity of user name - why RFC 3261 is more strict then RFC 
2543 [RESEND]

Thanks 
--Avshalom