librenms/scripts/ifAlias
ollb 698584e14d feature: Add support for dynamic interfaces in ifAlias script (#6005)
* add support for dynamic interfaces in ifAlias script

* netlink and ip support alias (`ip link set IFACE alias ALIAS`). In an
  environment with dynamic interfaces, it is useful to be able retrieve
  aliases from ip.

* we cannot assume next iface oid is n + 1 since oids do not necessarily
  follow incrementally when some interfaces has been destroyed and
  recreated.

* use straight POSIX shell

* I agree to the conditions of the Contributor Agreement contained in
doc/General/Contributing.md.
2017-02-26 23:22:03 +00:00

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#!/bin/sh
# (c) 2013-2017, f0o@devilcode.org, olb@nebkha.net
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
DISTRO_BIN="/usr/bin/distro"
BASE='.1.3.6.1.2.1.31.1.1.1.18'
GET_TYPE="$1"
GET_OID="$2"
# cache ip link output
IP_LINK="$(ip link)"
# Get interface id from GET_OID script parameter depending on the get type -g
# or -n.
#
# snmpd specify two behaviors: GETNEXT and GET.
#
# script -g <GET_OID>
#
# : Should return OID value
#
# script -n <GET_OID>
#
# : Should return next OID value
#
# Note that interface id are not necessarly following incrementally.
# We need tho find the next interface id (which is not necessarily n+1).
#
interface_id()
{
local N=
local L=
local ID="${GET_OID#${BASE}.}"
case "$GET_TYPE" in
-g)
echo "$ID"
return 0
;;
-n)
if [ "$ID" = "$BASE" ]
then
# find the first iface_id
echo "$IP_LINK" | grep -oE "^[0-9]+:" | head -n 1 | cut -d':' -f 1
return 0
else
# find the next iface_id
for N in $(echo "$IP_LINK" | grep -oE "^[0-9]+:" | cut -d':' -f 1)
do
if [ "$L" = "$ID" -o ! "$ID" ]
then
echo -n "$N"
return 0
fi
L="$N"
done
fi
;;
esac
return 1
}
interface_name()
{
local IFACE_ID="$1"
echo "$IP_LINK" | grep -oE "^${IFACE_ID}: [^:@ ]*" | cut -d " " -f 2
}
alias_from_interfaces_config_file()
{
local IFACE="$1"
local CONFIG_FILE=
if [ -x "$DISTRO_BIN" ]
then
case "$("$DISTRO_BIN" | cut -d " " -f 1)" in
Debian)
CONFIG_FILE="/etc/network/interfaces"
;;
Gentoo)
CONFIG_FILE="/etc/conf.d/net"
;;
CentOS|RedHat|SuSE|Mandriva|Mandrake)
CONFIG_FILE="/etc/sysconfig/network-scripts/ifcfg-$IFACE"
;;
Archlinux)
CONFIG_FILE="/etc/conf.d/net-conf-$IFACE"
;;
esac
fi
if [ "$CONFIG_FILE" ]
then
echo "$(grep -i "^# $IFACE:" $CONFIG_FILE | sed "s/^# $IFACE: //i")"
fi
}
alias_from_ip_link()
{
local IFACE="$1"
ip link show "$IFACE" | grep -e "^[[:space:]]*alias[[:space:]]" | sed -e 's/^[[:space:]]*alias //'
}
IFACE_ID="$(interface_id)"
[ "$IFACE_ID" ] || exit
IFACE="$(interface_name "$IFACE_ID")"
VALUE=
# we first try to get alias from interface config file
[ "$VALUE" ] || VALUE="$(alias_from_interfaces_config_file "$IFACE")"
# then from ip link show $IFACE output
[ "$VALUE" ] || VALUE="$(alias_from_ip_link "$IFACE")"
echo "${BASE}.${IFACE_ID}"
echo "string"
echo "$VALUE"
exit 0