ddns-scripts: add support for glue records

Assuming the following dns zone configuration for kresin.me:

.                   1800  IN  NS  ns.inwx.de.
home.kresin.me.     1800  IN  NS  gw.home.kresin.me.
gw.home.kresin.me.  60    IN  A   198.51.100.1

Using the example, gw.home.kresin.me is a glue record and used as DDNS
record as well. gw.home.kresin.me points to the OpenWrt installation
where the ddns-scripts are running.

Since ns.inwx.de isn't the authoritative server for home.kresin.me,
a query for the the A record of gw.home.kresin.me will be "forwarded"
to and replied by the authoritative server 198.51.100.1. If the
authoritative server can't be reached, the query times out without any
address returned.

The only way to get the A record of the glue record is to use bind
host in verbose output mode, query ns.inwx.de for gw.home.kresin.me and
evaluate the additional section of the response.

To my knowledge, only bind host in verbose output mode shows the
additional section of the response. Therefore, this features depends on
bind host.

It is not possible to use the bind host verbose mode for all queries.
In verbose mode the "has address" line isn't returned. Grepping for the
hostname might fail if the hostname is CNAME. Grepping for the first
occurrence of an ip-address is way to error prone, since it could
return the ip address of a different record type.

Signed-off-by: Mathias Kresin <dev@kresin.me>

diff --git a/net/ddns-scripts/Makefile b/net/ddns-scripts/Makefile
index 3724d36d5ef295042ff0d9023c203f3f705bb195..5e6f3acdfde7e87633c185eb55d640cddd51b236 100755 (executable)
--- a/net/ddns-scripts/Makefile
+++ b/net/ddns-scripts/Makefile
@@ -12,7 +12,7 @@ PKG_NAME:=ddns-scripts
 PKG_VERSION:=2.7.1
 # Release == build
 # increase on changes of services files or tld_names.dat
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_LICENSE:=GPL-2.0
 PKG_MAINTAINER:=Christian Schoenebeck <christian.schoenebeck@gmail.com>

diff --git a/net/ddns-scripts/files/dynamic_dns_functions.sh b/net/ddns-scripts/files/dynamic_dns_functions.sh
index 72deca0bf475c51530dd74ba3d92bc827913f246..93a35c8c30aa3611f0088ef94e460d70f659c968 100755 (executable)
--- a/net/ddns-scripts/files/dynamic_dns_functions.sh
+++ b/net/ddns-scripts/files/dynamic_dns_functions.sh
@@ -956,6 +956,7 @@ get_registered_ip() {
        # 1     no IP detected
 
        [ $# -lt 1 -o $# -gt 2 ] && write_log 12 "Error calling 'get_registered_ip()' - wrong number of parameters"
+       [ $is_glue -eq 1 ] && [ -z "$(which host)" ] && write_log 12 "Update of glue records is only supported using BIND host"
        write_log 7 "Detect registered/public IP"
 
        # set correct regular expression
@@ -968,6 +969,7 @@ get_registered_ip() {
                        [ $use_ipv6 -eq 0 ] && __PROG="$__PROG -4"  || __PROG="$__PROG -6"
                fi
                [ $force_dnstcp -eq 1 ] && __PROG="$__PROG -T"  # force TCP
+               [ $is_glue -eq 1 ] && __PROG="$__PROG -v" # use verbose output to get additional section
 
                __RUNPROG="$__PROG $lookup_host $dns_server >$DATFILE 2>$ERRFILE"
                __PROG="BIND host"
@@ -1039,6 +1041,12 @@ get_registered_ip() {
                else
                        if [ "$__PROG" = "BIND host" ]; then
                                __DATA=$(cat $DATFILE | awk -F "address " '/has/ {print $2; exit}' )
+
+                               if [ $is_glue -eq 1 ]; then
+                                       __DATA=$(cat $DATFILE | grep "^$lookup_host" | grep -m 1 -o "$__REGEX" )
+                               else
+                                       __DATA=$(cat $DATFILE | awk -F "address " '/has/ {print $2; exit}' )
+                               fi
                        elif [ "$__PROG" = "Knot host" ]; then
                                __DATA=$(cat $DATFILE | awk -F "address " '/has/ {print $2; exit}' )
                        elif [ "$__PROG" = "drill" ]; then

diff --git a/net/ddns-scripts/files/dynamic_dns_updater.sh b/net/ddns-scripts/files/dynamic_dns_updater.sh
index 02a61dfe90205a900c9bddb6050337c19aaff1be..31dac5eff64097b000f9f7e3b47c9fb89c56accf 100755 (executable)
--- a/net/ddns-scripts/files/dynamic_dns_updater.sh
+++ b/net/ddns-scripts/files/dynamic_dns_updater.sh
@@ -110,6 +110,7 @@ trap "trap_handler 15" 15   # SIGTERM       Termination
 # force_dnstcp         force communication with DNS server via TCP instead of default UDP
 # proxy                        using a proxy for communication !!! ALSO used to detect local IP via web => return proxy's IP !!!
 # use_logfile          self-explanatory "/var/log/ddns/$SECTION_ID.log"
+# is_glue                      the record that should be updated is a glue record
 #
 # some functionality needs
 # - GNU Wget or cURL installed for sending updates to DDNS service