Re: Using libnetdissect in other code, outside tcpdump source tree

[Bill Fenner via tcpdump-workers <tcpdump-workers () lists tcpdump org>]

> --- Begin Message ---
>
>
> From: Bill Fenner <fenner () gmail com>
>
> Date: Fri, 14 Aug 2020 11:54:07 -0400
>
> On Wed, Aug 12, 2020 at 6:22 PM Guy Harris <gharris () 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
>
> --- End Message ---
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