contrib/package/freifunk-gwcheck/files/usr/sbin/ff_olsr_test_gw.sh

   1 #!/bin/sh
   2 # Copyright 2013 Manuel Munz <freifunk at somakoma dot de>
   3 # Licensed under the GNU General Public License (GPL) v3
   4 # This script monitors the local internet gateway
   5
   6 . /lib/functions.sh
   7 . /lib/functions/network.sh
   8 . /usr/share/libubox/jshn.sh
   9
  10 # exit if dyngw_plain is not enabled or RtTable is not (254 or unset)
  11 config_load olsrd
  12
  13 check_dyngw_plain()
  14 {
  15         local cfg="$1"
  16         config_get library "$cfg" library
  17         if [ "${library#olsrd_dyn_gw_plain}" != "$library" ]; then
  18                 config_get ignore "$cfg" ignore
  19                 config_get RtTable "$cfg" RtTable
  20                 if [ "$ignore" != "1" ] && [ -z "$RtTable" -o "$RtTable" = "254" ]; then
  21                         exit=0
  22                 fi
  23         fi
  24 }
  25
  26 exit=1
  27 config_foreach check_dyngw_plain LoadPlugin
  28 [ "$exit" = "1" ] && exit 1
  29
  30 #Exit if this script is already running
  31 pid="$(pidof ff_olsr_test_gw.sh)"
  32 if [ ${#pid} -gt 5 ]; then
  33         logger -p debug -t gwcheck "Gateway check script is already running, exit now"
  34         exit 1
  35 fi
  36
  37 # exit if there is no defaultroute with metric=0 in main or gw-check table.
  38 defroutemain="$(ip route show |grep default |grep -v metric)"
  39 defroutegwcheck="$(ip route show table gw-check |grep default |grep -v metric)"
  40 if [ -z "$defroutegwcheck" -a -z "$defroutemain" ]; then
  41         exit 1
  42 fi
  43
  44 # get and shuffle list of testservers
  45 testserver="$(uci -q get freifunk-gwcheck.hosts.host)"
  46 [ -z "$testserver" ] && echo "No testservers found, exit" && exit
  47
  48 testserver="$(for t in $testserver; do echo $t; done | awk 'BEGIN {
  49         srand();
  50 }
  51 {
  52         l[NR] = $0;
  53 }
  54
  55 END {
  56         for (i = 1; i <= NR; i++) {
  57                 n = int(rand() * (NR - i + 1)) + i;
  58                 print l[n];
  59                 l[n] = l[i];
  60         }
  61 }')"
  62
  63 check_internet() {
  64         for t in $testserver; do
  65                 local test
  66                 test=$(wget -q http://$t/conntest.html -O -| grep "Internet_works")
  67                 if [ "$test" == "Internet_works" ]; then
  68                         echo 0
  69                         break
  70                 else
  71                         logger -p debug -t gw-check "Could not fetch http://$t/conntest.html"
  72                 fi
  73         done
  74 }
  75
  76 resolve() {
  77         echo "$(nslookup $1 2>/dev/null |grep 'Address' |grep -v '127.0.0.1' |awk '{ print $3 }')"
  78 }
  79
  80 get_dnsservers() {
  81         # this gets all dns servers for the interface which has the default route
  82
  83         dns=""
  84         if [ ! -x /bin/ubus ]; then
  85                 # ubus not present (versions before Attitude): fallback to get these from /var/state/network.
  86                 # We always assume that wan is the default route interface here
  87                 dns="$(grep network.wan.resolv_dns /var/state/network | cut -d "=" -f 2)"
  88         else
  89                 network_find_wan wan
  90                 network_get_dnsserver dns $wan
  91         fi
  92 }
  93
  94 iw=$(check_internet)
  95
  96 if [ "$iw" == 0 ]; then
  97         # Internet available again, restore default route and remove ip rules
  98         if [ -n "$defroutegwcheck" ]; then
  99                 ip route add $defroutegwcheck
 100                 ip route del $defroutegwcheck table gw-check
 101                 for host in $testserver; do
 102                         ips="$(resolve $host)"
 103                         for ip in $ips; do
 104                                 [ -n "$(ip rule show | grep "to $ip lookup gw-check")" ] && ip rule del to $ip table gw-check
 105                         done
 106                 done
 107                 get_dnsservers
 108                 for d in $dns; do
 109                         [ -n "$(ip rule show | grep "to $d lookup gw-check")" ] && ip rule del to $d table gw-check
 110                 done
 111                 logger -p err -t gw-check "Internet is available again, default route restored ( $defroutegwcheck)"
 112         fi
 113
 114 else
 115         # Check failed. Move default route to table gw-check and setup ip rules.
 116         if [ -z "$(ip rule show | grep gw-check)" -a -n "$defroutemain" ]; then
 117                 ip route add $defroutemain table gw-check
 118                 ip route del $defroutemain
 119                 logger -p err -t gw-check "Internet is not available, default route deactivated ( $defroutemain)"
 120         fi
 121         for host in $testserver; do
 122                 ips="$(resolve $host)"
 123                 for ip in $ips; do
 124                         [ -z "$(ip rule show | grep "to $ip lookup gw-check")" ] && ip rule add to $ip table gw-check
 125                 done
 126         done
 127         get_dnsservers
 128         for d in $dns; do
 129                 [ -z "$(ip rule show | grep "to $d lookup gw-check")" ] && ip rule add to $d table gw-check
 130         done
 131         logger -p err -t gw-check "Check your internet connection!"
 132 fi