Subject: Re: DHCP client, integration with ifconfig, etc.
To: Bill Sommerfeld <firstname.lastname@example.org>
From: Matt Thomas <email@example.com>
Date: 02/09/1997 19:10:24
At 06:27 PM 2/9/97 -0500, Bill Sommerfeld wrote:
> It turns out that when you're mobile, some daemons don't behave
> properly, so another thing this script might do is to shut down
> some daemons and restart them when the IP address changes.
>An idea which has occurred to me was to add a new signal,
>SIGIFCH, analogous to SIGWINCH, which is delivered to user
>processes expressing interest in it when the "local address set" of a
For IPv6 I've been thinking this idea for quite awhile. I want
to include such a mechanism into the IPv6 Advanced API RFC I'm
coauthoring with Richard Stevens.
One method is to use a signal, possibly one of p1003.1b (realtime)
signals. setsockopt(fd, IPPROTO_IPV6, IPV6_SIGADDRCH, &signo, sizeof(signo))
which would the signal in signo to be delivered to the owner of the
socket (via fcntl).
I'm not happy with that though because I believe signals are evil. It
does have the advantage of requiring little infrastucture changes.
Another is a socket with an exception condition via select/poll. Though
a setsockopt would be needed to enable this and to clear the condition.
Another is the return of a new errno, EADDREXPIRED, on bound sockets to an
Any one have any preferences?
Matt Thomas Internet: firstname.lastname@example.org
UNIX Networking WWW URL: http://ftp.digital.com/%7Ethomas/
Digital Equipment Corporation Disclaimer: This message reflects my own
Littleton, MA warped views, etc.