host/fix-ip6-default-route.sh

   1 #!/bin/sh
   2 export PATH=${PATH}:/sbin
   3 NETCFG=/etc/network/interfaces
   4
   5 [ "$1" = "-v" ] && DEBUG="printf" || DEBUG="true"
   6
   7 lastiface=""
   8 lastgateway=""
   9
  10 while read -r line
  11 do
  12         if echo "${line}" | grep -q "[ \t]*#"
  13         then
  14                 false
  15         elif echo "${line}" | grep -q "^iface [^ ]* inet6 [^ ]*$"
  16         then
  17                 echo "${line}" | ( IFS=' ' read -r _ iface _ method
  18                         "${DEBUG}" "Found %s with method %s.\n" "${iface}" "${method}"
  19                         if [ "${method}" != "static" ]
  20                         then
  21                                 "${DEBUG}" "Interface %s does not use static configuration. Ambiguous config, exiting.\n" "${iface}"
  22                                 exit 2
  23                         fi
  24                 ) || exit $?
  25                 lastiface="${line}"
  26         elif [ -n "${lastiface}" ]
  27         then
  28                 if gateway=$(echo "${line}" | grep -o "gateway *[0-9a-fA-F:]*:[0-9a-fA-F:]*")
  29                 then
  30                         if [ -z "${lastgateway}" ]
  31                         then
  32                                 lastgateway="${gateway}"
  33                                 "${DEBUG}" "Found %s for %s.\n" "${lastgateway}" "${lastiface}"
  34                         else
  35                                 "${DEBUG}" "A gateway was already defined for another interface. Ambiguous situation, exiting.\n"
  36                                 exit 3
  37                         fi
  38                 fi
  39         fi
  40 done < "${NETCFG}"
  41
  42 if [ -z "${lastiface}" ]
  43 then
  44         "${DEBUG}" "No inet6 interface config found.\n"
  45         exit 1
  46 else
  47         iface=$(echo "${lastiface}" | grep -oP "(?<=iface )[^ ]*(?= inet6)")
  48         "${DEBUG}" "Checking if %s needs to be reconfigured...\n" "${iface}"
  49 fi
  50
  51 defroute=$(ip -6 route | grep "^default ")
  52 if [ -z "${defroute}" ] || echo "${defroute}" | grep -q " proto ra "
  53 then
  54         # If we get here, we will provide output of our actions. It is not affected by verbose mode.
  55         printf "No default route, or it is RA-configured. Reconfiguring %s...\n" "${iface}"
  56         ifdown -v "${iface}"
  57         ip link set "${iface}" down
  58         ifup -v "${iface}"
  59 else
  60         "${DEBUG}" "Found healthy default route: %s.\nNo action is necessary.\n" "${defroute}"
  61 fi