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#!/bin/bash
# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# A list of functions which get executed for each netlink event received.
# These are configured by the files included below.
GBMC_IP_MONITOR_HOOKS=()
# Load configurations from a known location in the filesystem to populate
# hooks that are executed after each event.
shopt -s nullglob
for conf in /usr/share/gbmc-ip-monitor/*.sh; do
source "$conf"
done
gbmc_ip_monitor_run_hooks() {
local hook
for hook in "${GBMC_IP_MONITOR_HOOKS[@]}"; do
"$hook" || continue
done
}
gbmc_ip_monitor_generate_init() {
ip link | sed 's,^[^ ],[LINK]\0,'
local intf=
local line
while read line; do
[[ "$line" =~ ^([0-9]+:[[:space:]][^:]+) ]] && intf="${BASH_REMATCH[1]}"
[[ "$line" =~ ^[[:space:]]*inet ]] && echo "[ADDR]$intf $line"
done < <(ip addr)
ip -4 route | sed 's,^,[ROUTE],'
ip -6 route | sed 's,^,[ROUTE],'
echo '[INIT]'
}
GBMC_IP_MONITOR_DEFER_OUTSTANDING=
gbmc_ip_monitor_defer_() {
sleep 1
printf '[DEFER]\n' >&$GBMC_IP_MONITOR_DEFER
}
gbmc_ip_monitor_defer() {
[ -z "$GBMC_IP_MONITOR_DEFER_OUTSTANDING" ] || return 0
gbmc_ip_monitor_defer_ &
GBMC_IP_MONITOR_DEFER_OUTSTANDING=1
}
gbmc_ip_monitor_parse_line() {
local line="$1"
if [[ "$line" == '[INIT]'* ]]; then
change=init
echo "Initialized" >&2
elif [[ "$line" == '[ADDR]'* ]]; then
change=addr
action=add
pfx_re='^\[ADDR\](Deleted )?[0-9]+:[[:space:]]*'
intf_re='([^ ]+)[[:space:]]+'
fam_re='([^ ]+)[[:space:]]+'
addr_re='([^/]+)/[0-9]+[[:space:]]+(brd[[:space:]]+[^ ]+[[:space:]]+)?'
scope_re='scope[[:space:]]+([^ ]+)[[:space:]]*(.*)'
combined_re="${pfx_re}${intf_re}${fam_re}${addr_re}${scope_re}"
if ! [[ "$line" =~ ${combined_re} ]]; then
echo "Failed to parse addr: $line" >&2
return 1
fi
if [ -n "${BASH_REMATCH[1]}" ]; then
action=del
fi
intf="${BASH_REMATCH[2]}"
fam="${BASH_REMATCH[3]}"
ip="${BASH_REMATCH[4]}"
scope="${BASH_REMATCH[6]}"
flags="${BASH_REMATCH[7]}"
elif [[ "$line" == '[ROUTE]'* ]]; then
line="${line#[ROUTE]}"
change=route
action=add
if ! [[ "$line" =~ ^\[ROUTE\](Deleted )?(.*)$ ]]; then
echo "Failed to parse link: $line" >&2
return 1
fi
if [ -n "${BASH_REMATCH[1]}" ]; then
action=del
fi
route="${BASH_REMATCH[2]}"
elif [[ "$line" == '[LINK]'* ]]; then
change=link
action=add
pfx_re='^\[LINK\](Deleted )?[0-9]+:[[:space:]]*'
intf_re='([^:]+):[[:space:]]+'
if ! [[ "$line" =~ ${pfx_re}${intf_re} ]]; then
echo "Failed to parse link: $line" >&2
return 1
fi
if [ -n "${BASH_REMATCH[1]}" ]; then
action=del
fi
intf="${BASH_REMATCH[2]}"
read line || break
data=($line)
mac="${data[1]}"
elif [[ "$line" == '[DEFER]'* ]]; then
GBMC_IP_MONITOR_DEFER_OUTSTANDING=
change=defer
else
return 2
fi
}
return 0 2>/dev/null
cleanup() {
local st="$?"
trap - HUP INT QUIT ABRT TERM EXIT
jobs -l -p | xargs -r kill || true
exit $st
}
trap cleanup HUP INT QUIT ABRT TERM EXIT
FIFODIR="$(mktemp -d)"
mkfifo "$FIFODIR"/fifo
exec {GBMC_IP_MONITOR_DEFER}<>"$FIFODIR"/fifo
rm -rf "$FIFODIR"
while read line; do
gbmc_ip_monitor_parse_line "$line" || continue
gbmc_ip_monitor_run_hooks || continue
if [ "$change" = 'init' ]; then
systemd-notify --ready
fi
done < <(gbmc_ip_monitor_generate_init; ip monitor link addr route label & cat <&$GBMC_IP_MONITOR_DEFER)
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