release/src/router/dnsmasq/debian/resolvconf

   1 #!/bin/sh
   2 #
   3 # Script to update the resolver list for dnsmasq
   4 #
   5 # N.B. Resolvconf may run us even if dnsmasq is not (yet) running.
   6 # If dnsmasq is installed then we go ahead and update the resolver list
   7 # in case dnsmasq is started later.
   8 #
   9 # Assumption: On entry, PWD contains the resolv.conf-type files.
  10 #
  11 # This file is part of the dnsmasq package.
  12 #
  13
  14 set -e
  15
  16 RUN_DIR="/var/run/dnsmasq"
  17 RSLVRLIST_FILE="${RUN_DIR}/resolv.conf"
  18 TMP_FILE="${RSLVRLIST_FILE}_new.$$"
  19 MY_RECORD_NAME="lo.dnsmasq"
  20 DNSCRYPT_RECORD_NAME="lo.dnscrypt"
  21
  22 [ -x /usr/sbin/dnsmasq ] || exit 0
  23 [ -x /lib/resolvconf/list-records ] || exit 1
  24
  25 PATH=/bin:/sbin
  26
  27 report_err() { echo "$0: Error: $*" >&2 ; }
  28
  29 # Stores arguments (minus duplicates) in RSLT, separated by spaces
  30 # Doesn't work properly if an argument itself contains whitespace
  31 uniquify()
  32 {
  33         RSLT=""
  34         while [ "$1" ] ; do
  35                 for E in $RSLT ; do
  36                         [ "$1" = "$E" ] && { shift ; continue 2 ; }
  37                 done
  38                 RSLT="${RSLT:+$RSLT }$1"
  39                 shift
  40         done
  41 }
  42
  43 if [ ! -d "$RUN_DIR" ] && ! mkdir --parents --mode=0755 "$RUN_DIR" ; then
  44         report_err "Failed trying to create directory $RUN_DIR"
  45         exit 1
  46 fi
  47
  48 RSLVCNFFILES=""
  49 for F in $(/lib/resolvconf/list-records) ; do
  50         case "$F" in
  51           "$MY_RECORD_NAME")
  52                 # Omit
  53                 ;;
  54           "$DNSCRYPT_RECORD_NAME")
  55                 # Dnscrypt, I only have eyes for you
  56                 RSLVCNFFILES="$DNSCRYPT_RECORD_NAME"
  57                 break
  58                 ;;
  59           *)
  60                 RSLVCNFFILES="${RSLVCNFFILES:+$RSLVCNFFILES }$F"
  61                 ;;
  62         esac
  63 done
  64
  65 NMSRVRS=""
  66 if [ "$RSLVCNFFILES" ] ; then
  67         uniquify $(sed -n -e 's/^[[:space:]]*nameserver[[:space:]]\+//p' $RSLVCNFFILES)
  68         NMSRVRS="$RSLT"
  69 fi
  70
  71 # Dnsmasq uses the mtime of $RSLVRLIST_FILE, with a resolution of one second,
  72 # to detect changes in the file. This means that if a resolvconf update occurs
  73 # within one second of the previous one then dnsmasq may fail to notice the
  74 # more recent change. To work around this problem we sleep one second here
  75 # if necessary in order to ensure that the new mtime is different.
  76 if [ -f "$RSLVRLIST_FILE" ] && [ "$(ls -go --time-style='+%s' "$RSLVRLIST_FILE" | { read p h s t n ; echo "$t" ; })" = "$(date +%s)" ] ; then
  77         sleep 1
  78 fi
  79
  80 clean_up() { rm -f "$TMP_FILE" ; }
  81 trap clean_up EXIT
  82 : >| "$TMP_FILE"
  83 for N in $NMSRVRS ; do echo "nameserver $N" >> "$TMP_FILE" ; done
  84 mv -f "$TMP_FILE" "$RSLVRLIST_FILE"
  85