lmtpd NUL rejection

[simon.brady at otago.ac.nz]

On Fri, 10 Jan 2003, Igor Brezac wrote:

> Have you tried F=1 mailer flag?  This may only work in Sendmail 8.12.x.
> 
> From op.txt:
> 
> 1   Don't send null characters ('\0') to this  mailer.

We've gone live with 8.12.7, and F=1 is doing just what we hoped for: 
silently deleting NULs in transit. Thanks again for the pointer.

Along the way, I've discovered a related bug in lmtpd (2.1.11). If a
misconfigured client sends a message with lines longer than 8190 chars,
the following code in imap/lmtpengine.c (lines 672-675) will incorrectly
report the presence of NULs:

             else if (p[0] != '\n') {
                 /* line contained a \0 not at the end */
                 r = IMAP_MESSAGE_CONTAINSNULL;
                 continue;

(It assumes all lines end with '\n', which prot_fgets() doesn't 
guarantee.)

I'm not sure what the right fix is for this. It's trivial to identify the 
long-line case, but should lmtpd return an error (and if so, what?), or 
should it try to handle this pathological case?

--
Simon Brady                             mailto:simon.brady at otago.ac.nz
ITS Technical Services
University of Otago, Dunedin, New Zealand