ipconfig: handle case of delayed DHCP server
If a DHCP server is delayed, it's possible for the client to receive the
DHCPOFFER after it has already sent out a new DHCPDISCOVER message from
a second interface. The client then sends out a DHCPREQUEST from the
second interface, but the server doesn't recognize the device and
rejects the request.
This patch simply tracks the current device being configured and throws
away the OFFER if it is not intended for the current device. A more
sophisticated approach would be to put the OFFER information into the
struct ic_device rather than storing it globally.
Signed-off-by: Chris Friesen <cfriesen@nortel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 90d22ae..88bf051 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -139,6 +139,8 @@
__be32 root_server_addr = NONE; /* Address of NFS server */
u8 root_server_path[256] = { 0, }; /* Path to mount as root */
+u32 ic_dev_xid; /* Device under configuration */
+
/* vendor class identifier */
static char vendor_class_identifier[253] __initdata;
@@ -932,6 +934,13 @@
goto drop_unlock;
}
+ /* Is it a reply for the device we are configuring? */
+ if (b->xid != ic_dev_xid) {
+ if (net_ratelimit())
+ printk(KERN_ERR "DHCP/BOOTP: Ignoring delayed packet \n");
+ goto drop_unlock;
+ }
+
/* Parse extensions */
if (ext_len >= 4 &&
!memcmp(b->exten, ic_bootp_cookie, 4)) { /* Check magic cookie */
@@ -1115,6 +1124,9 @@
get_random_bytes(&timeout, sizeof(timeout));
timeout = CONF_BASE_TIMEOUT + (timeout % (unsigned) CONF_TIMEOUT_RANDOM);
for (;;) {
+ /* Track the device we are configuring */
+ ic_dev_xid = d->xid;
+
#ifdef IPCONFIG_BOOTP
if (do_bootp && (d->able & IC_BOOTP))
ic_bootp_send_if(d, jiffies - start_jiffies);