Date: Sat, 30 Jun 2001 11:34:11 -0600 From: Wes Peters <wes@softweyr.com> To: Igor Podlesny <poige@morning.ru> Cc: freebsd-hackers@FreeBSD.ORG, freebsd-isp@freebsd.org Subject: Re: Flight of the rat, living wreck..... Message-ID: <3B3E0D93.79738728@softweyr.com> References: <754836544.20010630185133@morning.ru>
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Igor Podlesny wrote:
> > /*
> > * Macro for finding the interface (ifnet structure) corresponding to one
> > * of our IP addresses.
> > */
> > #define INADDR_TO_IFP(addr, ifp) \
> > /* struct in_addr addr; */ \
> > /* struct ifnet *ifp; */ \
> > { \
> > register struct in_ifaddr *ia; \
> > \
> > for (ia = in_ifaddrhead.tqh_first; \
>
> // so here we start looking through the queue
>
> > ia != NULL
>
> // sanity (I'd have written just (ia))
>
> > && ((ia->ia_ifp->if_flags & IFF_POINTOPOINT)? \
>
> // hm. special case if the interface is PTP
>
> > IA_DSTSIN(ia):IA_SIN(ia))->sin_addr.s_addr != (addr).s_addr; \
>
> // so it is like: if it is PTP, then we using DST address in comparison
> // with addr.s_addr
>
> // it is the time I started to ask myself why it is so? why we're (ok,
> // they're) checking for remote ip-address if the head comment
> // says:
> // * Macro for finding the interface (ifnet structure) corresponding to one
> // * of our IP addresses.
> // ^^^
> // ^^^
With point-to-point connections, the address at the opposite end of the
connection is always used in the route table. When the interface is
created as a point-to-point interface, a route is automatically entered
from the local address to the opposite address. The "corresponding"
in the comment at the beginning of the macro is interpreted rather loosely.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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