#!/bin/sh
|
#
|
# Script to update the resolver list for dnsmasq
|
#
|
# N.B. Resolvconf may run us even if dnsmasq is not (yet) running.
|
# If dnsmasq is installed then we go ahead and update the resolver list
|
# in case dnsmasq is started later.
|
#
|
# Assumption: On entry, PWD contains the resolv.conf-type files.
|
#
|
# This file is part of the dnsmasq package.
|
#
|
|
set -e
|
|
RUN_DIR="/run/dnsmasq"
|
RSLVRLIST_FILE="${RUN_DIR}/resolv.conf"
|
TMP_FILE="${RSLVRLIST_FILE}_new.$$"
|
MY_NAME_FOR_RESOLVCONF="dnsmasq"
|
|
[ -x /usr/bin/dnsmasq ] || exit 0
|
[ -x /lib/resolvconf/list-records ] || exit 1
|
|
PATH=/bin:/sbin
|
|
report_err() { echo "$0: Error: $*" >&2 ; }
|
|
# Stores arguments (minus duplicates) in RSLT, separated by spaces
|
# Doesn't work properly if an argument itself contains whitespace
|
uniquify()
|
{
|
RSLT=""
|
while [ "$1" ] ; do
|
for E in $RSLT ; do
|
[ "$1" = "$E" ] && { shift ; continue 2 ; }
|
done
|
RSLT="${RSLT:+$RSLT }$1"
|
shift
|
done
|
}
|
|
if [ ! -d "$RUN_DIR" ] && ! mkdir --parents --mode=0755 "$RUN_DIR" ; then
|
report_err "Failed trying to create directory $RUN_DIR"
|
exit 1
|
fi
|
|
RSLVCNFFILES=""
|
for F in $(/lib/resolvconf/list-records --after "lo.$MY_NAME_FOR_RESOLVCONF") ; do
|
case "$F" in
|
"lo.$MY_NAME_FOR_RESOLVCONF")
|
# Omit own record
|
;;
|
lo.*)
|
# Include no more records after one for a local nameserver
|
RSLVCNFFILES="${RSLVCNFFILES:+$RSLVCNFFILES }$F"
|
break
|
;;
|
*)
|
RSLVCNFFILES="${RSLVCNFFILES:+$RSLVCNFFILES }$F"
|
;;
|
esac
|
done
|
|
NMSRVRS=""
|
if [ "$RSLVCNFFILES" ] ; then
|
uniquify $(sed -n -e 's/^[[:space:]]*nameserver[[:space:]]\+//p' $RSLVCNFFILES)
|
NMSRVRS="$RSLT"
|
fi
|
|
# Dnsmasq uses the mtime of $RSLVRLIST_FILE, with a resolution of one second,
|
# to detect changes in the file. This means that if a resolvconf update occurs
|
# within one second of the previous one then dnsmasq may fail to notice the
|
# more recent change. To work around this problem we sleep one second here
|
# if necessary in order to ensure that the new mtime is different.
|
if [ -f "$RSLVRLIST_FILE" ] && [ "$(stat -c %X "$RSLVRLIST_FILE")" = "$(date +%s)" ] ; then
|
sleep 1
|
fi
|
|
clean_up() { rm -f "$TMP_FILE" ; }
|
trap clean_up EXIT
|
: >| "$TMP_FILE"
|
for N in $NMSRVRS ; do echo "nameserver $N" >> "$TMP_FILE" ; done
|
mv -f "$TMP_FILE" "$RSLVRLIST_FILE"
|
