udhcpc: paranoia when using kernel UDP mode for sending renew: server ID may be bogus
With new code, we request that target IP (server ID) must be directly reachable.
If it's not, this happens:
udhcpc: waiting 2000 seconds
udhcpc: entering listen mode: kernel
udhcpc: opening listen socket on *:68 wlan0
udhcpc: entering renew state
udhcpc: sending renew to 1.1.1.1
udhcpc: send: Network is unreachable
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1.1.1.1 needs routing, this is fishy!
udhcpc: entering rebinding state
udhcpc: entering listen mode: raw
udhcpc: created raw socket
udhcpc: sending renew to 0.0.0.0
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ going to use broadcast
which is the desired behavior. Before the patch, packet to 1.1.1.1 was routed
over eth0 (!) and maybe even into Internet (!!!).
function old new delta
udhcpc_main 2752 2763 +11
udhcp_send_kernel_packet 295 301 +6
send_renew 82 84 +2
send_packet 166 168 +2
bcast_or_ucast 23 25 +2
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/0 up/down: 23/0) Total: 23 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 05ddc86..57d8b36 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -588,7 +588,9 @@
udhcp_send_kernel_packet(dhcp_pkt,
server_config.server_nip, SERVER_PORT,
- dhcp_pkt->gateway_nip, SERVER_PORT);
+ dhcp_pkt->gateway_nip, SERVER_PORT,
+ /*send_flags:*/ 0
+ );
}
static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)