--dhcp-reply-delay option to workaround PXE client bugs.
Adds option to delay replying to DHCP packets by one or more seconds.
This provides a workaround for a PXE boot firmware implementation
that has a bug causing it to fail if it receives a (proxy) DHCP
reply instantly.
On Linux it looks up the exact receive time of the UDP packet with
the SIOCGSTAMP ioctl to prevent multiple delays if multiple packets
come in around the same time.
diff --git a/src/rfc2131.c b/src/rfc2131.c
index 3e97402..6a8f0db 100644
--- a/src/rfc2131.c
+++ b/src/rfc2131.c
@@ -64,9 +64,10 @@
static struct dhcp_opt *pxe_opts(int pxe_arch, struct dhcp_netid *netid, struct in_addr local, time_t now);
struct dhcp_boot *find_boot(struct dhcp_netid *netid);
static int pxe_uefi_workaround(int pxe_arch, struct dhcp_netid *netid, struct dhcp_packet *mess, struct in_addr local, time_t now, int pxe);
-
+static void apply_delay(u32 xid, time_t recvtime, struct dhcp_netid *netid);
+
size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
- size_t sz, time_t now, int unicast_dest, int *is_inform, int pxe, struct in_addr fallback)
+ size_t sz, time_t now, int unicast_dest, int *is_inform, int pxe, struct in_addr fallback, time_t recvtime)
{
unsigned char *opt, *clid = NULL;
struct dhcp_lease *ltmp, *lease = NULL;
@@ -918,6 +919,8 @@
log_packet("PXE", NULL, emac, emac_len, iface_name, ignore ? "proxy-ignored" : "proxy", NULL, mess->xid);
log_tags(tagif_netid, ntohl(mess->xid));
+ if (!ignore)
+ apply_delay(mess->xid, recvtime, tagif_netid);
return ignore ? 0 : dhcp_packet_size(mess, agent_id, real_end);
}
}
@@ -1058,7 +1061,7 @@
}
log_tags(tagif_netid, ntohl(mess->xid));
-
+ apply_delay(mess->xid, recvtime, tagif_netid);
log_packet("DHCPOFFER" , &mess->yiaddr, emac, emac_len, iface_name, NULL, NULL, mess->xid);
time = calc_time(context, config, option_find(mess, sz, OPTION_LEASE_TIME, 4));
@@ -2626,6 +2629,29 @@
}
}
+static void apply_delay(u32 xid, time_t recvtime, struct dhcp_netid *netid)
+{
+ struct delay_config *delay_conf;
+
+ /* Decide which delay_config option we're using */
+ for (delay_conf = daemon->delay_conf; delay_conf; delay_conf = delay_conf->next)
+ if (match_netid(delay_conf->netid, netid, 0))
+ break;
+
+ if (!delay_conf)
+ /* No match, look for one without a netid */
+ for (delay_conf = daemon->delay_conf; delay_conf; delay_conf = delay_conf->next)
+ if (match_netid(delay_conf->netid, netid, 1))
+ break;
+
+ if (delay_conf)
+ {
+ if (!option_bool(OPT_QUIET_DHCP))
+ my_syslog(MS_DHCP | LOG_INFO, _("%u reply delay: %d"), ntohl(xid), delay_conf->delay);
+ delay_dhcp(recvtime, delay_conf->delay, -1, 0, 0);
+ }
+}
+
#endif