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On Wed, Aug 12, 2020 at 6:22 PM Guy Harris <ghar...@sonic.net> wrote:
> On Aug 12, 2020, at 1:31 PM, Guy Harris via tcpdump-workers <
> tcpdump-workers@lists.tcpdump.org> wrote:
>
> > We should probably have an include/libnetdissect directory in which we
> install netdissect.h and the headers it requires.
>
> Or include/netdissect.
>
> > However, API-declaring headers should *NEVER* require config.h (there
> was a particularly horrible case with OpenBSD's version of libz, forcing a
> painful workaround in Wireshark:
>
> ...
>
> > so if anything in netdissect.h depends on config.h definitions, we
> should try to fix that.
>
> It looks like it's just declaring replacements for strlcat(), strlcpy(),
> strdup(), and strsep() if the platform doesn't provide them. That should
> be done in a non-public header.
>
The specific reason for needing config.h was
#ifndef HAVE___ATTRIBUTE__
#define __attribute__(x)
#endif
because there's other code that doesn't work right without defining the
right attributes. Scrolling through netdissect.h, it relies on things
like __ATTRIBUTE___FORMAT_OK_FOR_FUNCTION_POINTERS to be able to fully
prototype the elements in netdissect_options. (There's probably an
argument that netdissect_options should be opaque, with the right accessors
and mutators for an API consumer. On the other hand, any API user probably
wants to provide ndo_printf, ndo_error, ndo_warning, which themselves have
the ndo as the first argument, hm.)
> That leaves ip.h and ip6.h; I'd have to check to see whether they should
> be considered part of the API or not.
>
> The comments are:
>
> #include "ip.h" /* struct ip for nextproto4_cksum() */
> #include "ip6.h" /* struct ip6 for nextproto6_cksum() */
>
> so what should probably be done is have a header for *users* of
> libnetdissect and a separate header for *components* of libnetdissect; the
> latter can define more things. (The latter would be a non-public header,
> unless we decide to support third-party dissector plugins; that would also
> mean we'd probably want to have something like Wireshark's dissector tables
> to which those plugins would add themselves.)
For my use case, "pretty_print_packet()" (and ndo_set_function_pointers() )
is the only public interface I need. I wonder if starting over with a
clean header file for API users would be a better start.
(Is sunrpcrequest_print() really part of the public api?)
Bill
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