Re: tcpdump build problems in latest CVS

[Guy Harris <guy () alum mit edu>]

On Fri, Jan 24, 2003 at 10:51:31PM -0600, Peter Fales wrote:
> I build tcpdump for a number of different platforms and I'm seeing 
> several problems in the latest CVS in that weren't in earlier versions:

Yes, there's a fair amount of new stuff that's been added to tcpdump
since, for example, the 3.7 series.

>   On some platforms (namely SunOS 4), sprintf doesn't return the number
>   of bytes written, so this doesn't work.  I usually change this to:
>
>       sprint(p, ...)
>       p += strlen(p);

I've checked a change like that in.

> - On platforms which don't have snprintf, the configure checks for
>   pcap_datalink_name_to_val and pcap_list_datalinks incorrectly
>   report "not found".  The conftest.c assumes that a link failure
>   is because this function is missing, but it is actually failing
>   because snprintf is not found.  (The references to snprintf are 
>   coming from libpcap, so perhaps this is a libpcap issue - has it 
>   just started calling  snprintf/vsnprint?)

Not recently - that's been the case for a couple of releases now, I
think.  The problem is that "pcap_datalink_name_to_val()" and
"pcap_list_datalinks()" are new, so the configure checks for them are
new.

I think we've seen other problems on platforms without snprintf - for
example, libpcap doesn't have its own snprintf that it includes if the
system doesn't supply it, so, on platforms without snprintf,
applications must supply their own "snprintf()" if they're to be linked
with libpcap.

We should perhaps take tcpdump's implementation, transplant it to
libpcap and perhaps give it the names "pcap_snprintf()" and
"pcap_vsnprintf()", have have the libpcap configure script check whether
snprintf is available on the system and:

        if so, #define "pcap_snprintf" as "snprintf" and
        "pcap_vsnprintf" as "vsnprintf" in some header file;

        if not, declare "pcap_snprintf()" and "pcap_vsnprintf()" in that
        header file.

If we were more ambitious, we could, instead, have libpcap *always*
define "pcap_snprintf()" and "pcap_vsnprintf()", and have them both be
wrappers that call "vsnprintf()" on systems that have it, and declare
them in "pcap.h".  However, tcpdump would still have to carry its own
version around, in case you build the latest tcpdump with the
vendor-supplied libpcap on a system lacking snprintf.

> - On Irix 6.2, /usr/include/sys/socket.h has a #define for sa_len.  This
>   breaks print-arp.c around line 162 which has its own sa_len variable.

I've renamed the variable.
-
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