busybox: udhcpc: fix 'ip route add' with multiple interfaces on the same network
The udhcpc script fails to properly set a default route when:
- 'ip' is present ($have_bin_ip -eq 1)
- there are 2 or more interfaces connected to the same network
(e.g. ethernet + wifi on the same home LAN / same DHCP server)
In this case, when the first interface gets an address from DHCP
(e.g. eth0), a default route is set correctly. When the second interface
(e.g. wlan0) gets its address, 'ip route add' without 'dev $interface' sets
the route on the other interface. The result looks like:
# ip route
default via 192.168.1.1 dev eth0 metric 5
default via 192.168.1.1 dev eth0 metric 10 # wrong dev here
192.168.1.0/24 dev eth0 scope link src 192.168.1.20
192.168.1.0/24 dev wlan0 scope link src 192.168.1.30
#
The situation might go unnoticed until eth0 is disconnected, because only
wlan0 is present but there is no route through wlan0.
Fix by explicitly passing "dev $interface" to 'ip route add'. Note that all
other 'ip' invocations already have "dev $interface" passed.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
