From owner-cvs-sys  Sun Mar 17 12:18:12 1996
Return-Path: owner-cvs-sys
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id MAA02711
          for cvs-sys-outgoing; Sun, 17 Mar 1996 12:18:12 -0800 (PST)
Received: from gvr.win.tue.nl (root@gvr.win.tue.nl [131.155.210.19])
          by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id MAA02705
          Sun, 17 Mar 1996 12:18:06 -0800 (PST)
Received: by gvr.win.tue.nl (8.6.12/1.53)
    id VAA21057; Sun, 17 Mar 1996 21:18:03 +0100
From: guido@gvr.win.tue.nl (Guido van Rooij)
Message-Id: <199603172018.VAA21057@gvr.win.tue.nl>
Subject: Re: cvs commit:  src/sys/netinet in.c
To: fenner@freefall.freebsd.org (Bill Fenner)
Date: Sun, 17 Mar 1996 21:18:03 +0100 (MET)
Cc: CVS-committers@freefall.freebsd.org, cvs-all@freefall.freebsd.org,
        cvs-sys@freefall.freebsd.org
In-Reply-To: <199603151708.JAA12346@freefall.freebsd.org> from "Bill Fenner" at Mar 15, 96 09:08:09 am
X-Mailer: ELM [version 2.4 PL24]
Content-Type: text
Sender: owner-cvs-sys@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

Bill Fenner wrote:
> 
> fenner      96/03/15 09:08:08
> 
>   Modified:    sys/netinet  in.c
>   Log:
>   Allow SIOCGIFBRDADDR and SIOCGIFNETMASK to return information about
>   aliases, if the alias address was passed in the struct ifreq.
>   Default to first address on the list, for backwards compatibility.
>   

What happens now when you want to do a broadcast for any ip address
on a system? The rpc code would generate <n> duplicate broadcasts
when there were <n-1> aliases on the same subnet as an interfaces' first
ip address. What happens now is that you get one broadcast plus
<n-1> directed udp packets to the alias ip itsself.
I don't really know a solution. 
Suppose an interface ed0 has ip address 192.1.1.1 (mask 0xffffff00)
and an alias 192.1.1.2. Now the code will return the following broadcast
addresses: 192.1.1.0 for the 192.1.1.1 case and
	   192.1.1.2 for the 192.1.1.2 case
I believe that is wrong. But to just make checks like `if the interface
has another ip address within the same subnet with a netmask != 0xffffffff
then return that other netmask' is a gross hack :-(

-Guido