diff for Freifunk dnsmasq startup script

jcomeau@aspire:~/rentacoder/jcomeau/freifunk$ bzr diff -r669 S50dnsmasq
=== modified file 'freifunk/S50dnsmasq'
--- freifunk/S50dnsmasq 2013-07-16 22:48:48 +0000
+++ freifunk/S50dnsmasq 2013-07-17 03:17:26 +0000
@@ -1,5 +1,38 @@
 #!/bin/sh
-
+inet_ntoa() {
+ # convert numeric address to dotted octet representation
+ # remember ash uses signed integers so trim sign bit!
+ a=$(((($1 >> 1) & 0x7fffffff) >> 23))
+ b=$((($1 & 0x00ff0000) >> 16))
+ c=$((($1 & 0x0000ff00) >> 8))
+ d=$(($1 & 0x000000ff))
+ echo $a.$b.$c.$d
+}
+inet_aton() {
+ # convert dotted octet notation to integer
+ n=0
+ shift=24
+ for octet in 1 2 3 4; do
+  m=$(echo $1 | cut -d. -f$octet)
+  n=$(($n | ($m << $shift)))
+  shift=$((shift - 8))
+ done
+ printf 0x%x $n
+}
+inet_test_functions() {
+ exit_status=0
+ for address in 0.0.0.0 1.2.3.4 255.254.253.252 255.255.255.255; do
+  number=$(inet_aton $address)
+  check=$(inet_ntoa $number)
+  if [ "$check" != "$address" ]; then
+   echo "Failed: $check != $address ($number)" >&2
+   exit_status=1
+  fi
+ done
+}
+calc_ip() {  # ipcalc without the preassigned variable names
+       ipcalc $* | cut -s -d= -f2-  # trailing - means "any remaining fields"
+}
 write_config()
 {
        cat>/var/etc/dnsmasq.conf<<EOF
@@ -39,20 +72,18 @@
                echo "dhcp-range=wired,$DHCPNET.$DHCPBEG,$DHCPNET.$DHCPEND,$LANMSK,$DHCPLEASE">>/var/etc/dnsmasq.conf
        ;;esac

-       WLDHCP=$(nvram get ff_wldhcp)
+       WLDHCP=$(nvram get ff_wldhcp | sed 's/,/:/g')
        IFS=\;
        for ENT in $WLDHCP; do
-               NET=${ENT%[:,]*}
-               MSK=${ENT#*[:,]}
-               case $NET in "");;*)case $MSK in "");;*)
-                       DHCPLEASE=2h
-                       DHCPBEG=$(ipcalc -n $NET|cut -d'.' -f4)
-                       DHCPBEG=$(( $DHCPBEG + 2 ))
-                       DHCPEND=$(ipcalc -b $NET|cut -d'.' -f4)
-                       DHCPEND=$(( $DHCPEND - 1 ))
-                       DHCPNET=$(ipcalc -n $NET|cut -d'=' -f2|cut -d'.' -f1-3)
-                       echo "dhcp-range=wlnat,$DHCPNET.$DHCPBEG,$DHCPNET.$DHCPEND,$MSK,$DHCPLEASE">>/var/etc/dnsmasq.conf
-               ;;esac;;esac
+               DHCPBEG=${ENT%%[/:]*}
+               [ -z "$DHCPBEG" ] && continue
+               SUBNET=$(echo $ENT | cut -s -d/ -f2 | cut -d: -f1)
+               [ -z "$SUBNET" ] && SUBNET=32
+               MSK=$(echo $ENT | cut -s -d: -f2)
+               [ -z "$MSK" ] && MSK=$(calc_ip -n 255.255.255.255/$SUBNET)
+               DHCPLEASE=2h
+               DHCPEND=$(inet_ntoa $(($(inet_aton $(calc_ip -b $DHCPBEG/$SUBNET)) - 1)))
+               echo "dhcp-range=wlnat,$DHCPBEG,$DHCPEND,$MSK,$DHCPLEASE">>/var/etc/dnsmasq.conf
        done

        WAN_HOSTNAME=$(nvram get wan_hostname)