From: Alex Tang <altitude@cic.net>
Date: Wed, 4 Oct 95 13:20:55 PDT
To: sameer@c2.org (sameer)
Subject: Re: New Netscape bug (in version 1.12)
In-Reply-To: <199510041800.LAA07074@infinity.c2.org>
Message-ID: <199510042020.QAA01358@petrified.cic.net>
MIME-Version: 1.0
Content-Type: text/plain


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On Wed Oct  4 14:00:26 1995: you scribbled...
>
> > How do I decide what is too long?  For example, when tracking down buffer
> > overflow problems for the security patch, we found an undocumented
> > static buffer limit of 64 bytes for the hostname passed to gethostbyname()
> > on IRIX.  Before we stumbled across this problem, we had a discussion
> > about what length we should truncate host names to.  People thought
> > that 128 characters was a reasonable limit, but it turned out that it
> > was too long.
>
>
> 	Isn't there a resolver #define or something in limits.h called
> MAXHOSTNAMELEN ? Something like that? (Perhaps not, but that's what I
> recall..)

The DNS RFC specifies that the max hostname should be 255 characters, with
a 63 character limit for each segment of the name (RFC1035, section
2.3.4.)

- --> 2.3.4. Size limits
- -->
- --> Various objects and parameters in the DNS have size limits.  They are
- --> listed below.  Some could be easily changed, others are more
- --> fundamental.
- -->
- --> labels          63 octets or less
- -->
- --> names           255 octets or less

But, some older systems (SunOS4, and IRIX, amongst others) have the
MAXHSTNAMELEN defined as 64 characters, so this limits the max name to 64.
Solaris2 has MAXHOSTNAMELEN defined to 255 characters.
(the define is in sys/param.h for sunos and solaris).  

just a point of interest...

...alex...

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