OpenSSH banner doesnot display multibyte characters like korean

[Bob Rasmussen]

I believe the standard multibyte encodings (Shift-JIS, Big-5, GBK, etc.) 
all avoid using bytes in the control character range (0x00 to 0x1F) for 
the second character.

Also, doesn't the SSH specification state that UTF-8 is the only allowable 
encoding for the banner?

On Tue, 27 Nov 2012, Roland Mainz wrote:

> On Tue, Nov 27, 2012 at 12:17 PM, balu chandra <balu9463 at gmail.com> wrote:
> > I did not come across any UTF8 implementation of strnvis.
> > Howver have modified strnvis() to display Multibyte char (tested the
> > fix with Korean char).
> > Though all calls to strnvis() could be extended to skip Multibyte char
> > this fix is limited to skipping only for Banner message(introduced a
> > flag for doing so).
> >
> > The fix is provided here for comments.
> >
> > [root at rhel62 bala]# diff -ur openssh6.1 openssh6.1_mod
> > diff -ur openssh6.1/openbsd-compat/vis.c openssh6.1_mod/openbsd-compat/vis.c
> > --- openssh6.1/openbsd-compat/vis.c     2012-11-27 16:12:23.986690241 +0530
> > +++ openssh6.1_mod/openbsd-compat/vis.c 2012-11-27 16:12:43.559859183 +0530
> [snip]
> 
> Erm... the problem with this code is that it is specific to UTF-8
> only... but there are other multibyte encodings which are still in
> common use (like ja_JP.PCK/ShiftJIS on Solaris/Linux, both are used
> and mandated by goverment customers) and GB18030 (which is a) "modern"
> (e.g. not "legacy" like some people call the EUC encodings) and b)
> mandatory in PRC[1] (China)).
> 
> AFAIK a possible fix would be to pass the data through the libc
> multibyte functions and filter anything out which looks like the ASCII
> control characters (since more or less all multibyte characters have
> ASCII as basis) + anything which matches |iswcntrl()|
> 
> [1]=Erm... does anyone know how "Red Flag Linux" solved this ?
> 
> ----
> 
> Bye,
> Roland
> 
> -- 
>   __ .  . __
>  (o.\ \/ /.o) roland.mainz at nrubsig.org
>   \__\/\/__/  MPEG specialist, C&&JAVA&&Sun&&Unix programmer
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>  (;O/ \/ \O;)
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> 

Regards,
....Bob Rasmussen,   President,   Rasmussen Software, Inc.

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