busybox/examples/var_service/dhcp_if/convert2ipconf
Denys Vlasenko 5a387e26c2 dhcp service example: rewrite "private network to mask" as case statement
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-02-08 10:37:05 +01:00

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#!/bin/sh
# convert:
# dhcptype=5
# serverid=172.16.42.102
# lease=97200
# interface=eth0
# ip=172.16.42.177
# subnet=255.255.255.0
# mask=24
# broadcast=172.16.22.255
# router=172.16.42.98
# dns=10.34.32.125 10.32.63.5 10.34.255.7 10.11.255.27
# domain=lab.example.com example.com
# ntpsrv=10.34.32.125 10.34.255.7
# into:
#let cfg=cfg+1
#if[$cfg]=...; ip[$cfg]=...; ipmask[$cfg]=.../...; gw[$cfg]=...; net[$cfg]=... dns[$cfg]=...
exec >/dev/null
#exec >"$0.out" # debug
exec 2>&1
test "$interface" || exit 1
test "$ip" || exit 1
# some servers do not return subnet option.
# guess it for standard private networks.
if ! test "$mask"; then
case "$ip" in
10.*)
mask=8;;
192.168.*)
mask=16;;
#172.16-31.x.x
172.1[6789].*)
mask=12;;
172.2[0123456789].*)
mask=12;;
172.3[01].*)
mask=12;;
esac
fi
# some servers do not return router option.
# assume DHCP server is the router.
if ! test "$router"; then
test "$serverid" && router="$serverid"
fi
{
echo "let cfg=cfg+1"
test "$interface" && echo "if[\$cfg]='$interface'"
test "$ip" && echo "ip[\$cfg]='$ip'"
test "$ip" && test "$mask" \
&& echo "ipmask[\$cfg]='$ip/$mask'"
test "$router" && echo "gw[\$cfg]='$router'"
test "$dns" && echo "dns[\$cfg]='$dns'"
# TODO: I never saw a dhcp server which correctly announces
# which subnet(s) is/are available thru advertised router
# Assume 0/0
echo "net[\$cfg]='0/0'"
} >"$1"