Wireshark · Wireshark-dev: Re: [Wireshark-dev] Problem in 'packet-f5ethtrailer.c'

[João Valverde <joao.valverde@xxxxxxxxxxxxxxxxxx>]

On 19/03/20 18:38, Guy Harris wrote:
> On Mar 19, 2020, at 7:40 AM, Gisle Vanem <gisle.vanem@xxxxxxxxx> wrote:
>
> > I'm surprised no one has come across this compile
> > error yet:
> > epan/dissectors/packet-f5ethtrailer.c(482): error C2143: syntax error: missing ';' before '.'
> > epan/dissectors/packet-f5ethtrailer.c(485): error C2224: left of '.S_addr' must have struct/union type
> > epan/dissectors/packet-f5ethtrailer.c(487): error C2224: left of '.S_addr' must have struct/union type
> >
> > (using MSVC-2019).
> >
> > Reason seems simple; <winsock2.h> has snuck in somehow and
> > added the wellknown "#define s_addr S_un.S_addr"
> This isn't unique to Windows.  It dates back to old BSD, in which struct in_addr contained a union of multiple different types for an IP address, with some types being structures breaking up the address into host and network bits, and even included bits for IMP numbers.  s_addr was defined to be the member of the union that just defined an address as a 32-bit integer, so if you referred to the s_addr "field" of the structure it gave you the 32-bit integer value.

Because POSIX defines struct in_addr as an opaque structure with an 
s_addr element, some BSD Socket implementations get creative with the 
use of unions and use a macro definition for "s_addr", which is terribly 
bad practice and a tremendously ugly botch.