X-Git-Url: https://git.distorted.org.uk/~mdw/dyndns/blobdiff_plain/751afaff7ba5d4e52d436dd874d997821df21fff..5b6e31a04dcadab3fd87327837eebc66992b1e97:/bin/update

diff --git a/bin/update b/bin/update
index a9c2716..5ff17fe 100755
--- a/bin/update
+++ b/bin/update
@@ -28,9 +28,35 @@ EOF
 getarg='case $# in 0) fail_usage ;; esac; arg=$1; shift'
 doneargs='case $# in 0) ;; *) fail_usage ;; esac'
 
+check_current_state () {
+  ck_rrty=$1 ck_name=$2
+  set -- $(adnshost --config "nameserver $DYNDNS_SERVER" \
+	    -Fi -Tt -t$ck_rrty "$ck_name")
+  case $1,$2,$3,$5 in
+    ";,failed,permfail,nxdomain" | ";,failed,permfail,nodata")
+      err=$5
+      ;;
+    ";,failed,"*)
+      shift 8
+      echo >&2 "$0: lookup $ck_name ($ck_rrty) failed: $*"
+      exit 4
+      ;;
+    *)
+      err=nil cur_ttl=$2 cur_addr=$4
+      ;;
+  esac
+}
+
 checkhost () {
   host=$1
 
+  case "$host" in
+    *..* | .* | *. | *[!-_.a-zA-Z0-9]*)
+      echo >&2 "$0: invalid hostname"
+      exit 2
+      ;;
+  esac
+
   matchp=nil
   for pat in $DYNDNS_HOST; do
     case "$host" in $pat) matchp=t ;; esac
@@ -40,13 +66,21 @@ checkhost () {
 
 doupdate () {
   cmd=$1
-
-nsupdate -k "$DYNDNS_KEY" <<EOF
+  case ${DYNDNS_TESTONLY_P-nil} in
+    nil)
+      nsupdate -k "$DYNDNS_KEY" <<EOF
 server $DYNDNS_SERVER
 zone $DYNDNS_ZONE
 $cmd
 send
 EOF
+      ;;
+    *)
+      cat <<EOF
+$cmd
+EOF
+      ;;
+  esac
 }
 
 eval $getarg; cmd=$arg
@@ -61,7 +95,7 @@ case "$cmd" in
       0,t,*) fail_usage ;;
       *,nil,"$client" | *,t,*) addr=$1; shift ;;
       *)
-	echo >&2 "$0: incorrect address (wanted = $2; found = $addr)"
+	echo >&2 "$0: incorrect address (wanted = $client; found = $1)"
 	exit 3
 	;;
     esac
@@ -73,15 +107,24 @@ case "$cmd" in
       *) echo >&2 "$0: failed to parse new address"; exit 2 ;;
     esac
     name=$host.$DYNDNS_ZONE
+    check_current_state $(echo $rrtype | tr A-Z a-z) "$name"
+    ttl=${DYNDNS_TTL-14400}
+    case $err,$cur_ttl,$cur_addr in
+      nil,$ttl,$addr) echo >&2 "$0: nothing to do"; exit 0 ;;
+    esac
     doupdate "
 	update delete $name IN $rrtype
-	update add $name ${DYNDNS_TTL-14400} IN $rrtype $addr"
+	update add $name $ttl IN $rrtype $addr"
     ;;
   unset)
     eval $getarg; host=$arg
     eval $doneargs
     checkhost "$host"
     name=$host.$DYNDNS_ZONE
+    check_current_state a "$name"
+    case $err in
+      nxdomain) echo >&2 "$0: nothing to do"; exit 0 ;;
+    esac
     doupdate "update delete $name IN"
     ;;
   *)