From e4ceab6648f954cfc240f805607c0a4da6b8f804 Mon Sep 17 00:00:00 2001
From: Erich Eckner <git@eckner.net>
Date: Mon, 1 Apr 2019 09:57:00 +0200
Subject: update-ddns.in: refactor

---
 update-ddns.in | 177 +++++++++++++++++++--------------------------------------
 1 file changed, 60 insertions(+), 117 deletions(-)

diff --git a/update-ddns.in b/update-ddns.in
index 7aef624..bd86294 100644
--- a/update-ddns.in
+++ b/update-ddns.in
@@ -15,143 +15,86 @@ if ! ipCmd=$(which ip 2> /dev/null); then
   done
 fi
 
-unset ignoreIps
-
-i=0
-
-while read -r ipVer updateUrl dnsName; do
-
-  if [[ "${ipVer}" = '#'* ]] || [ -z "${ipVer}" ]; then
-    continue
-  fi
+sed '
+  /^\(#\|\s\)/ d
+  s/^\([46]!\?\)\([46]!\?\)\(\s.*$\)/\1\3\n\2\3/
+' #ETCDIR#/update-ddns.conf \
+| while read -r ipVer updateUrl dnsName; do
 
   if [[ "${ipVer}" == 'ignore' ]]; then
-    ignoreIps="${ignoreIps} ${updateUrl} ${dnsName}"
+    ignoreIps=$(
+      printf '%s\n' "${ignoreIps}" "${updateUrl}" "${dnsName}" \
+      | grep -vxF '' \
+      | sort -u
+    )
     continue
   fi
 
-  if [[ "${ipVer}" == *"?" ]]; then
-    ipVer="${ipVer%?}"
+  if [ -z "${ipVer##*!}" ]; then
+    ipVer="${ipVer%!}"
+  else
     [ -z "$(${ipCmd} -o -${ipVer} addr show scope global)" ] && continue
   fi
 
   if [ "${ipVer}" == '4' ]; then
-    dnsVers[${i}]='A'
-    inetVers[${i}]='inet'
-    ipCmdVers[${i}]='-4'
+    dnsVer='A'
+    inetVer='inet'
+    ipRegex='[0-9.]\+'
   elif [ "${ipVer}" == '6' ]; then
-    dnsVers[${i}]='AAAA'
-    inetVers[${i}]='inet6'
-    ipCmdVers[${i}]='-6'
-  elif [ "${ipVer}" == '46' ] || [ "${ipVer}" == '64' ]; then
-    dnsVers[${i}]='A'
-    inetVers[${i}]='inet'
-    ipCmdVers[${i}]='-4'
-
-    updateUrls[${i}]="${updateUrl}"
-    dnsNamen[${i}]="${dnsName}"
-    i=$[${i}+1]
-
-    dnsVers[${i}]='AAAA'
-    inetVers[${i}]='inet6'
-    ipCmdVers[${i}]='-6'
+    dnsVer='AAAA'
+    inetVer='inet6'
+    ipRegex='[0-9a-f:]\+'
   else
-    >&2 echo 'Error: First column in "#ETCDIR#/update-ddns.conf" needs to be "4", "6", "46" or "64"!'
+    >&2 echo 'Syntax error in "#ETCDIR#/update-ddns.conf"!'
+    >&2 echo 'Syntax should be:'
+    >&2 echo '# comments start with "#" or white space'
+    >&2 echo '4/6/46/64 update-url dns-name/check-url'
+    >&2 echo 'digits in the first column may be followed by "!" to indicate'
+    >&2 echo 'that this ip version should be updated regardless of whether'
+    >&2 echo 'an according global ip was found (mostly useful with "auto")'
     exit 1
   fi
 
-  updateUrls[${i}]="${updateUrl}"
-  dnsNamen[${i}]="${dnsName}"
-
-  i=$[${i}+1]
-
-done < #ETCDIR#/update-ddns.conf
-
-ignoreIps='^\('"$(
-  echo ${ignoreIps} | \
-    tr '[:space:]' '\n' | \
-    grep -vxF '' | \
-    sort -u | \
-    sed '
-      s@$@\\|@
-    ' | \
-    tr -d '\n' | \
-    sed '
-      s@\\|$@@
-    '
-)"'\)$'
-
-err=0
-
-for dnsName in $( \
-  echo "${dnsNamen[@]}" | \
-    tr ' ' '\n' | \
-    sort -u
-); do
-  unset updateIps
-  unset updateUrl
-  unset curlForceIpVer
-  needsUpdate=false
-
-  for ((j=0; j<${i}; j++)); do
-    [ "${dnsName}" != "${dnsNamen[${j}]}" ] && continue
-
-    updateUrl="${updateUrls[${j}]}"
-
-    if [[ "${dnsName}" == *'/'* ]]; then
-      dnsIps=$(
-        curl ${ipCmdVers[${j}]} "${dnsName}" 2> /dev/null
-      )
-      ips='1'
-      updateIps="${updateIps}"',auto'
-      if [ -n "${curlForceIpVer}" ] && [ "${curlForceIpVer}" != "${ipCmdVers[${j}]}" ]; then
-        >&2 echo 'Error: I cannot determine two different ip versions automatically (because Erich didn'"'"'t need it).'
-        exit 1
-      fi
-      curlForceIpVer="${ipCmdVers[${j}]}"
+  if [ -z "${dnsName##*/*}" ]; then
+    dnsIps=$(
+      # this test yields 1 if the dns record is already properly set
+      curl -s${ipVer} "${dnsName}"
+    )
+    ips='1'
+    updateIps='auto'
+  else
+    dnsIps=$(
+      dig +short $1 "${dnsName}" ${dnsVers[${j}]} \
+      | grep -x "${ipRegex}" \
+      |sort -u
+    )
+    ips=$(
+      "${ipCmd}" -o -${ipVer} addr show scope global | \
+        awk '{print $4}' | \
+        cut -d/ -f1 | \
+        grep -vx "${ignoreIps}" | \
+        sort -u
+    )
+
+    if [ -z "${ips}" ]; then
+      updateIps='auto'
     else
-      dnsIps=$(
-        dig $1 "${dnsName}" ${dnsVers[${j}]} | \
-          sed '/^;; AUTHORITY SECTION:$/Q' | \
-          grep '^[^;]' | \
-          grep "\s${dnsVers[${j}]}\s" | \
-          awk '{print $5}' | \
-          sort -u
+      updateIps=$(
+        printf '%s\n' "${ips}" \
+        | tr '\n' ',' \
+        | sed 's/,$//'
       )
-
-      ips=$(
-        "${ipCmd}" -o ${ipCmdVers[${j}]} addr show scope global | \
-          awk '{print $4}' | \
-          cut -d/ -f1 | \
-          grep -vx "${ignoreIps}" | \
-          sort -u
-      )
-
-      if [ $(echo "${ips}" | grep -c '.') -eq 0 ]; then
-        updateIps="${updateIps}"',auto'
-        if [ -n "${curlForceIpVer}" ] && [ "${curlForceIpVer}" != "${ipCmdVers[${j}]}" ]; then
-          >&2 echo 'Error: I cannot determine two different ip versions automatically (because Erich didn'"'"'t need it).'
-          exit 1
-        fi
-        curlForceIpVer="${ipCmdVers[${j}]}"
-      else
-        updateIps="${updateIps},$(echo -n "${ips}" | tr '\n' ',')"
-      fi
     fi
+  fi
 
-    if [ "${dnsIps}" != "${ips}" ]; then
-      needsUpdate=true
-    fi
-  done
+  [ "${dnsIps}" = "${ips}" ] && continue
 
-  if ${needsUpdate}; then
-    if [[ "${updateUrl}" = *'?'* ]]; then
-      updateIps='&address='"${updateIps#,}"
-    else
-      updateIps='?address='"${updateIps#,}"
-    fi
-    curl ${curlForceIpVer} -sS "${updateUrl}${updateIps}" 2> /dev/null || err=$?
+  if [ -z "${updateUrl##*?*}" ]; then
+    updateIps='&address='"${updateIps}"
+  else
+    updateIps='?address='"${updateIps}"
   fi
+  curl -${ipVer} -sS "${updateUrl}${updateIps}" 2>/dev/null || err=$?
 done
 
 exit ${err}
-- 
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