rc(8) script -- waiting for the network to become usable

[Jeremy Chadwick]

On Tue, Apr 27, 2010 at 09:48:41AM +1000, Phil wrote:
> Jeremy, 
> A good proposal to improve start-up robustness. If I may suggest, 
> waitnetwork_ip should include a short list of alternate IP's in 
> the event of a local network outage, or DOS, etc.  Something like:
> waitnetwork_ip="IP1 IP2 IP3"
> 
> Having multiple target IP's will improve the likelihood of timely 
> booting when silly/nasty things happen on the wider network.
> 
> Good idea to have incorporated into the base system.

Phil,

I brought this point up in my post on -rc and -net, actually.  I've
since extended the script to support multiple IPs in $waitnetwork_ip
(wasn't that hard).  The logic is that if any of the IPs pass the ping
test, then the network connection is considered usable.

Attached is the modified script.  I'll be updating the version on my
server (HTTP) momentarily.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |


#!/bin/sh
#
# $FreeBSD: $
#

# PROVIDE: waitnetwork
# REQUIRE: NETWORKING
# BEFORE: mountcritremote
# KEYWORD: nojail

# XXX - Once/if committed to base, it's better to have mountcritremote
# XXX - REQUIRE waitnetwork, rather than use the above BEFORE line.

. /etc/rc.subr

name="waitnetwork"
rc_var=`set_rcvar`

start_cmd="waitnetwork_start"
stop_cmd=":"

# XXX - Once/if committed to base, the following defaults should
# XXX - be placed into src/etc/defaults/rc.conf instead of here
# XXX - Also be sure to keep waitnetwork_ip="" commented out!

waitnetwork_enable="NO"		# Wait for network availability before
				# continuing with NETWORKING rc scripts
#waitnetwork_ip=""		# IP address to ping
waitnetwork_count="5"		# ping count (see ping(8) -c flag)
waitnetwork_timeout="60"	# ping timeout (see ping(8) -t flag)

waitnetwork_start()
{
	local ip rc success

	success=0

	if [ -z "${waitnetwork_ip}" ]; then
		warn "You must define one or more IP addresses in waitnetwork_ip"
		return
	fi

	for ip in ${waitnetwork_ip}; do
		echo "Waiting for ${ip} to respond to ICMP..."

		if [ -z "${waitnetwork_timeout}" ]; then
			/sbin/ping -c ${waitnetwork_count} ${ip} >/dev/null 2>&1
			rc=$?
		else
			info "Using timeout of ${waitnetwork_timeout} seconds"
			/sbin/ping -t ${waitnetwork_timeout} -c ${waitnetwork_count} ${ip} >/dev/null 2>&1
			rc=$?
		fi

		if [ $rc -eq 0 ]; then
			echo "Host reachable; network considered available."
			return
		else
			echo "No response from host."
		fi
	done

	echo "Exhausted IP list.  Continuing with startup, but be aware you may"
	echo "not have a fully functional networking layer at this point."
}

load_rc_config $name
run_rc_command "$1"