ip/ifcfg

   1 #! /bin/sh
   2 # SPDX-License-Identifier: GPL-2.0
   3
   4 CheckForwarding () {
   5   local sbase fwd
   6   sbase=/proc/sys/net/ipv4/conf
   7   fwd=0
   8   if [ -d $sbase ]; then
   9     for dir in $sbase/*/forwarding; do
  10       fwd=$(( fwd + $(cat "$dir") ))
  11     done
  12   else
  13     fwd=2
  14   fi
  15   return $fwd
  16 }
  17
  18 RestartRDISC () {
  19   killall -HUP rdisc || rdisc -fs
  20 }
  21
  22 ABCMaskLen () {
  23   local class;
  24
  25   class=${1%%.*}
  26   if [ "$1" = "" -o $class -eq 0 -o $class -ge 224 ]; then return 0
  27   elif [ $class -ge 224 ]; then return 0
  28   elif [ $class -ge 192 ]; then return 24
  29   elif [ $class -ge 128 ]; then return 16
  30   else return 8; fi
  31 }
  32
  33 label="label $1"
  34 ldev="$1"
  35 dev=${1%:*}
  36 if [ "$dev" = "" -o "$1" = "help" ]; then
  37   echo "Usage: ifcfg DEV [[add|del [ADDR[/LEN]] [PEER] | stop]" 1>&2
  38   echo "       add - add new address" 1>&2
  39   echo "       del - delete address" 1>&2
  40   echo "       stop - completely disable IP" 1>&2
  41   exit 1
  42 fi
  43 shift
  44
  45 CheckForwarding
  46 fwd=$?
  47 if [ $fwd -ne 0 ]; then
  48   echo "Forwarding is ON or its state is unknown ($fwd). OK, No RDISC." 1>&2
  49 fi
  50
  51
  52 deleting=0
  53 case "$1" in
  54 add) shift ;;
  55 stop)
  56   if [ "$ldev" != "$dev" ]; then
  57     echo "Cannot stop alias $ldev" 1>&2
  58     exit 1;
  59   fi
  60   ip -4 addr flush dev $dev $label || exit 1
  61   if [ $fwd -eq 0 ]; then RestartRDISC; fi
  62   exit 0 ;;
  63 del*)
  64   deleting=1; shift ;;
  65 *)
  66 esac
  67
  68 ipaddr=
  69 pfxlen=
  70 if [ "$1" != "" ]; then
  71   ipaddr=${1%/*}
  72   if [ "$1" != "$ipaddr" ]; then
  73     pfxlen=${1#*/}
  74   fi
  75   if [ "$ipaddr" = "" ]; then
  76     echo "$1 is bad IP address." 1>&2
  77     exit 1
  78   fi
  79 fi
  80 shift
  81
  82 peer=$1
  83 if [ "$peer" != "" ]; then
  84   if [ "$pfxlen" != "" -a "$pfxlen" != "32" ]; then
  85     echo "Peer address with non-trivial netmask." 1>&2
  86     exit 1
  87   fi
  88   pfx="$ipaddr peer $peer"
  89 else
  90   if [ "$ipaddr" = "" ]; then
  91     echo "Missing IP address argument." 1>&2
  92     exit 1
  93   fi
  94   if [ "$pfxlen" = "" ]; then
  95     ABCMaskLen $ipaddr
  96     pfxlen=$?
  97   fi
  98   pfx="$ipaddr/$pfxlen"
  99 fi
 100
 101 if [ "$ldev" = "$dev" -a "$ipaddr" != "" ]; then
 102   label=
 103 fi
 104
 105 if [ $deleting -ne 0 ]; then
 106   ip addr del $pfx dev $dev $label || exit 1
 107   if [ $fwd -eq 0 ]; then RestartRDISC; fi
 108   exit 0
 109 fi
 110
 111
 112 if ! ip link set up dev $dev ; then
 113   echo "Error: cannot enable interface $dev." 1>&2
 114   exit 1
 115 fi
 116 if [ "$ipaddr" = "" ]; then exit 0; fi
 117
 118 if ! arping -q -c 2 -w 3 -D -I $dev $ipaddr ; then
 119   echo "Error: some host already uses address $ipaddr on $dev." 1>&2
 120   exit 1
 121 fi
 122
 123 if ! ip address add $pfx brd + dev $dev $label; then
 124   echo "Error: failed to add $pfx on $dev." 1>&2
 125   exit 1
 126 fi
 127
 128 arping -q -A -c 1 -I $dev $ipaddr
 129 noarp=$?
 130 ( sleep 2 ;
 131   arping -q -U -c 1 -I $dev $ipaddr ) >/dev/null 2>&1 </dev/null &
 132
 133 ip route add unreachable 224.0.0.0/24 >/dev/null 2>&1
 134 ip route add unreachable 255.255.255.255 >/dev/null 2>&1
 135 if [ "`ip link ls $dev | grep -c MULTICAST`" -ge 1 ]; then
 136   ip route add 224.0.0.0/4 dev $dev scope global >/dev/null 2>&1
 137 fi
 138
 139 if [ $fwd -eq 0 ]; then
 140   if [ $noarp -eq 0 ]; then
 141     ip ro append default dev $dev metric 30000 scope global
 142   elif [ "$peer" != "" ]; then
 143     if ping -q -c 2 -w 4 $peer ; then
 144       ip ro append default via $peer dev $dev metric 30001
 145     fi
 146   fi
 147   RestartRDISC
 148 fi
 149
 150 exit 0