examples/wins_hook/dns_update

   1 #!/bin/sh
   2 #
   3 # Example script for "wins hook".  This attempts to update the DNS with
   4 # new A records for the NETBIOS name that Samba passes us. We do this
   5 # the simple way, by deleting all DNS records for the name and then
   6 # readding all the expected 'A' records.
   7 #
   8 # Written by Stephen Rothwell <sfr@linuxcare.com>
   9 #
  10
  11 #
  12 # Configurable things
  13 #
  14 # The domain in which to create names
  15 #   YOU MUST CHANGE THIS
  16 # N.B. include the trailing dot
  17 #
  18 # It is a good idea to use a subdomain of your primary domain to ensure
  19 # that rogue machines can't take over (or delete) important names on
  20 # your network.
  21 DOMAIN=wins.example.com.
  22
  23 #
  24 # The DNS TTL to give the records (in seconds)
  25 #
  26 TTL=3600
  27 #
  28 # NETBIOS name types that we want to create DNS records for:
  29 #       20 is server
  30 #       00 is workstation
  31 #       03 is user
  32 #
  33 USEFUL_TYPES="20 00 03"
  34 #
  35 # The name of a cache file to use to avoid continual updates
  36 # of the same name and IP addresses.  If you comment this out
  37 # then the cache is not kept at all.
  38 #
  39 #CACHE_FILE=/usr/local/samba/var/wins_update.cache
  40
  41 if [ $# -lt 4 ]; then
  42         echo "Usage: $0 op name type ttl [ip_addr ...]" 1>&2
  43         echo "       op is one of add, refresh, delete" 1>&2
  44         echo "       name is the NETBIOS name" 1>&2
  45         echo "       type is the NETBIOS name type" 1>&2
  46         echo "       ttl is the NETBIOS time to live" 1>&2
  47         echo "       ip_addr's are the remaining IP addresses for this name" 1>&2
  48         exit 1
  49 fi
  50
  51 NSUPDATE=`which nsupdate`
  52 [ -x "$NSUPDATE" ] || NSUPDATE=/usr/bin/nsupdate
  53 [ -x "$NSUPDATE" ] || NSUPDATE=/sbin/nsupdate
  54 [ -x "$NSUPDATE" ] || NSUPDATE=/usr/sbin/nsupdate
  55 [ -x "$NSUPDATE" ] || {
  56         echo "Cannot find nsupdate." 1>&2
  57         exit 1
  58 }
  59
  60 OP=$1
  61 NAME=$2
  62 TYPE=$3
  63 WINS_TTL=$4
  64 shift 4
  65 IP_ADDRS="$@"
  66
  67 do_update=0
  68 for i in $USEFUL_TYPES
  69 do
  70         [ "$TYPE" = "$i" ] && do_update=1
  71 done
  72 [ $do_update = 1 ] || exit 0
  73
  74 if [ -n "$CACHE_FILE" ]; then
  75         if [ -r "$CACHE_FILE" ]; then
  76                 fgrep -q -x -i "$NAME $IP_ADDRS" "$CACHE_FILE" &&
  77                         exit 0
  78                 grep -v -i "^$NAME " "$CACHE_FILE" >"$CACHE_FILE".$$
  79         fi
  80         echo "$NAME $IP_ADDRS" >>"$CACHE_FILE".$$
  81         mv "$CACHE_FILE" "$CACHE_FILE".old 2>/dev/null
  82         mv "$CACHE_FILE".$$ "$CACHE_FILE"
  83 fi
  84
  85 {
  86         echo update delete $NAME.$DOMAIN
  87         for i in $IP_ADDRS
  88         do
  89                 echo update add $NAME.$DOMAIN $TTL A $i
  90         done
  91         echo
  92 } 2>/dev/null | $NSUPDATE >/dev/null 2>&1 &
  93
  94 exit 0