mdw@git.distorted.org.uk Git - dyndns/blob - bin/update

   1 #! /bin/sh
   2
   3 set -e
   4 . ./dyndns.conf
   5
   6 ## Check that the environment is set up properly.
   7 for i in DYNDNS_ZONE DYNDNS_HOST DYNDNS_SERVER DYNDNS_KEY SSH_CLIENT; do
   8   eval havep=\${$i+t}\${$i-nil}
   9   case $havep in nil) echo >&2 "$0: variable $i unset"; exit 2 ;; esac
  10 done
  11
  12 ## Find the client address.  This may be useful.
  13 set -- $SSH_CLIENT; client=$1
  14
  15 ## Parse the commad line.
  16 set -- $SSH_ORIGINAL_COMMAND
  17
  18 fail_usage () {
  19   cat >&2 <<EOF
  20 usage: $0 COMMAND ARGS...
  21
  22 Commands:
  23         set [-force] HOST [ADDR]
  24         unset HOST
  25 EOF
  26   exit 1
  27 }
  28 getarg='case $# in 0) fail_usage ;; esac; arg=$1; shift'
  29 doneargs='case $# in 0) ;; *) fail_usage ;; esac'
  30
  31 check_current_state () {
  32   ck_rrty=$1 ck_name=$2
  33   set -- $(adnshost --config "nameserver $DYNDNS_SERVER" \
  34             -Fi -Tt -t$ck_rrty "$ck_name")
  35   case $1,$2,$3,$5 in
  36     ";,failed,permfail,nxdomain" | ";,failed,permfail,nodata")
  37       err=$5
  38       ;;
  39     ";,failed,"*)
  40       shift 8
  41       echo >&2 "$0: lookup $ck_name ($ck_rrty) failed: $*"
  42       exit 4
  43       ;;
  44     *)
  45       err=nil cur_ttl=$2 cur_addr=$4
  46       ;;
  47   esac
  48 }
  49
  50 checkhost () {
  51   host=$1
  52
  53   case "$host" in
  54     *..* | .* | *. | *[!-_.a-zA-Z0-9]*)
  55       echo >&2 "$0: invalid hostname"
  56       exit 2
  57       ;;
  58   esac
  59
  60   matchp=nil
  61   for pat in $DYNDNS_HOST; do
  62     case "$host" in $pat) matchp=t ;; esac
  63   done
  64   case $matchp in nil) echo >&2 "$0: hostname not permitted"; exit 2 ;; esac
  65 }
  66
  67 doupdate () {
  68   cmd=$1
  69   case ${DYNDNS_TESTONLY_P-nil} in
  70     nil)
  71       nsupdate -k "$DYNDNS_KEY" <<EOF
  72 server $DYNDNS_SERVER
  73 zone $DYNDNS_ZONE
  74 $cmd
  75 send
  76 EOF
  77       ;;
  78     *)
  79       cat <<EOF
  80 $cmd
  81 EOF
  82       ;;
  83   esac
  84 }
  85
  86 eval $getarg; cmd=$arg
  87 case "$cmd" in
  88   set)
  89     forcep=nil
  90     eval $getarg
  91     case "$arg" in -force) forcep=t; eval $getarg ;; esac
  92     host=$arg
  93     case "$#,$forcep,$1" in
  94       0,nil,*) addr=$client ;;
  95       0,t,*) fail_usage ;;
  96       *,nil,"$client" | *,t,*) addr=$1; shift ;;
  97       *)
  98         echo >&2 "$0: incorrect address (wanted = $client; found = $1)"
  99         exit 3
 100         ;;
 101     esac
 102     eval $doneargs
 103     checkhost "$host"
 104     case $addr in
 105       *:*) rrtype=AAAA ;;
 106       *.*) rrtype=A ;;
 107       *) echo >&2 "$0: failed to parse new address"; exit 2 ;;
 108     esac
 109     name=$host.$DYNDNS_ZONE
 110     check_current_state $(echo $rrtype | tr A-Z a-z) "$name"
 111     ttl=${DYNDNS_TTL-14400}
 112     case $err,$cur_ttl,$cur_addr in
 113       nil,$ttl,$addr) echo >&2 "$0: nothing to do"; exit 0 ;;
 114     esac
 115     doupdate "
 116         update delete $name IN $rrtype
 117         update add $name $ttl IN $rrtype $addr"
 118     ;;
 119   unset)
 120     eval $getarg; host=$arg
 121     eval $doneargs
 122     checkhost "$host"
 123     name=$host.$DYNDNS_ZONE
 124     check_current_state a "$name"
 125     case $err in
 126       nxdomain) echo >&2 "$0: nothing to do"; exit 0 ;;
 127     esac
 128     doupdate "update delete $name IN"
 129     ;;
 130   *)
 131     fail_usage
 132     ;;
 133 esac