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freebsd/etc/rc.d/netwait
Ian Lepore 630c9dba7a Enhance rc.d/netwait script to wait for late-attaching interfaces such as
USB NICs.

USB network hardware may not be enumerated and available when the rc.d
networking scripts run. Eventually the USB attachment completes and devd
events cause the network initialization to happen, but by then other rc.d
scripts have already failed, because services which depend on NETWORKING
(such as mountcritremote) may end up running before the network is actually
ready.

There is an existing netwait script, but because it is dependent on
NETWORKING it runs too late to prevent failure of some other rc
scripts. This change flips the order so that NETWORKING depends on netwait,
and netwait now depends on devd and routing (the former is needed to make
interfaces appear, and the latter is needed to run the ping tests in
netwait).

The netwait script used to be oriented primarily towards "as soon as any
host is reachable the network is fully functional", so you gave it a list of
IPs to try and you could optionally name an interface and it would wait for
carrier on that interface. That functionality still works the same, but now
you can provide a list of interfaces to wait for and it waits until each one
of them is available. The ping logic still completes as soon as the first IP
on the list responds.

These changes were submitted by Brenden Molloy <brendan+freebsd@bbqsrc.net>
in PR 205186, and lightly modified by me to allow a list of interfaces
instead of just one.

PR:		205186
Differential Revision:	https://reviews.freebsd.org/D4608 (timeout w/o review)
2015-12-26 18:21:32 +00:00

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#!/bin/sh
# $FreeBSD$
#
# PROVIDE: netwait
# REQUIRE: devd routing
# KEYWORD: nojail
#
# The netwait script helps handle two situations:
# - Systems with USB or other late-attaching network hardware which
# is initialized by devd events. The script waits for all the
# interfaces named in the netwait_if list to appear.
# - Systems with statically-configured IP addresses in rc.conf(5).
# The IP addresses in the netwait_ip list are pinged. The script
# waits for any single IP in the list to respond to the ping. If your
# system uses DHCP, you should probably use synchronous_dhclient="YES"
# in your /etc/rc.conf instead of netwait_ip.
# Either or both of the wait lists can be used (at least one must be
# non-empty if netwait is enabled).
. /etc/rc.subr
name="netwait"
rcvar="netwait_enable"
start_cmd="${name}_start"
stop_cmd=":"
netwait_start()
{
local ip rc count output link wait_if got_if any_error
if [ -z "${netwait_if}" ] && [ -z "${netwait_ip}" ]; then
err 1 "No interface or IP addresses listed, nothing to wait for"
fi
if [ ${netwait_timeout} -lt 1 ]; then
err 1 "netwait_timeout must be >= 1"
fi
if [ -n "${netwait_if}" ]; then
any_error=0
for wait_if in ${netwait_if}; do
echo -n "Waiting for ${wait_if}"
link=""
got_if=0
count=1
# Handle SIGINT (Ctrl-C); force abort of while() loop
trap break SIGINT
while [ ${count} -le ${netwait_if_timeout} ]; do
if output=`/sbin/ifconfig ${wait_if} 2>/dev/null`; then
if [ ${got_if} -eq 0 ]; then
echo -n ", interface present"
got_if=1
fi
link=`expr "${output}" : '.*[[:blank:]]status: \(no carrier\)'`
if [ -z "${link}" ]; then
echo ', got link.'
break
fi
fi
sleep 1
count=$((count+1))
done
# Restore default SIGINT handler
trap - SIGINT
if [ ${got_if} -eq 0 ]; then
echo ", wait failed: interface never appeared."
any_error=1
elif [ -n "${link}" ]; then
echo ", wait failed: interface still has no link."
any_error=1
fi
done
if [ ${any_error} -eq 1 ]; then
warn "Continuing with startup, but be aware you may not have "
warn "a fully functional networking layer at this point."
fi
fi
if [ -n "${netwait_ip}" ]; then
# Handle SIGINT (Ctrl-C); force abort of for() loop
trap break SIGINT
for ip in ${netwait_ip}; do
echo -n "Waiting for ${ip} to respond to ICMP ping"
count=1
while [ ${count} -le ${netwait_timeout} ]; do
/sbin/ping -t 1 -c 1 -o ${ip} >/dev/null 2>&1
rc=$?
if [ $rc -eq 0 ]; then
# Restore default SIGINT handler
trap - SIGINT
echo ', got response.'
return
fi
count=$((count+1))
done
echo ', failed: No response from host.'
done
# Restore default SIGINT handler
trap - SIGINT
warn "Exhausted IP list. Continuing with startup, but be aware you may"
warn "not have a fully functional networking layer at this point."
fi
}
load_rc_config $name
run_rc_command "$1"