There are cases where binding to source IP and
destination IP is insufficient to guarantee sane
xmit netdev.
One case where this can fail is when
route-matching netdev carrier is down (cable
unplugged, wifi disconnected), or the netdev is
admin down. Then all the IP based bindings (bind()
+ connect()) will seemingly succeed but the actual
packet can go out through a default gw path.
Depending on the network this happens on
it can create issues or false alarms. It can
also leak some subnet info across networks that
shouldn't be routed.
As such better be safe than sorry and bind to a
netdev to be sure it's used for xmit.
function old new delta
udhcp_send_kernel_packet 293 336 +43
send_packet 182 188 +6
bcast_or_ucast 37 43 +6
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(add/remove: 0/0 grow/shrink: 3/0 up/down: 55/0) Total: 55 bytes
Signed-off-by: Michal Kazior <michal@plume.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
b817699e6c