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a752c0a452
DHCP connectivity issues can currently occur if the following conditions
are met:
1) A DHCP packet from a client to a server
2) This packet has a multicast destination
3) This destination has a matching entry in the translation table
(FF:FF:FF:FF:FF:FF for IPv4, 33:33:00:01:00:02/33:33:00:01:00:03
for IPv6)
4) The orig-node determined by TT for the multicast destination
does not match the orig-node determined by best-gateway-selection
In this case the DHCP packet will be dropped.
The "gateway-out-of-range" check is supposed to only be applied to
unicasted DHCP packets to a specific DHCP server.
In that case dropping the the unicasted frame forces the client to
retry via a broadcasted one, but now directed to the new best
gateway.
A DHCP packet with broadcast/multicast destination is already ensured to
always be delivered to the best gateway. Dropping a multicasted
DHCP packet here will only prevent completing DHCP as there is no
other fallback.
So far, it seems the unicast check was implicitly performed by
expecting the batadv_transtable_search() to return NULL for multicast
destinations. However, a multicast address could have always ended up in
the translation table and in fact is now common.
To fix this potential loss of a DHCP client-to-server packet to a
multicast address this patch adds an explicit multicast destination
check to reliably bail out of the gateway-out-of-range check for such
destinations.
The issue and fix were tested in the following three node setup:
- Line topology, A-B-C
- A: gateway client, DHCP client
- B: gateway server, hop-penalty increased: 30->60, DHCP server
- C: gateway server, code modifications to announce FF:FF:FF:FF:FF:FF
Without this patch, A would never transmit its DHCP Discover packet
due to an always "out-of-range" condition. With this patch,
a full DHCP handshake between A and B was possible again.
Fixes:
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|---|---|---|
| .. | ||
| bat_algo.c | ||
| bat_algo.h | ||
| bat_iv_ogm.c | ||
| bat_iv_ogm.h | ||
| bat_v.c | ||
| bat_v.h | ||
| bat_v_elp.c | ||
| bat_v_elp.h | ||
| bat_v_ogm.c | ||
| bat_v_ogm.h | ||
| bitarray.c | ||
| bitarray.h | ||
| bridge_loop_avoidance.c | ||
| bridge_loop_avoidance.h | ||
| debugfs.c | ||
| debugfs.h | ||
| distributed-arp-table.c | ||
| distributed-arp-table.h | ||
| fragmentation.c | ||
| fragmentation.h | ||
| gateway_client.c | ||
| gateway_client.h | ||
| gateway_common.c | ||
| gateway_common.h | ||
| hard-interface.c | ||
| hard-interface.h | ||
| hash.c | ||
| hash.h | ||
| icmp_socket.c | ||
| icmp_socket.h | ||
| Kconfig | ||
| log.c | ||
| log.h | ||
| main.c | ||
| main.h | ||
| Makefile | ||
| multicast.c | ||
| multicast.h | ||
| netlink.c | ||
| netlink.h | ||
| network-coding.c | ||
| network-coding.h | ||
| originator.c | ||
| originator.h | ||
| routing.c | ||
| routing.h | ||
| send.c | ||
| send.h | ||
| soft-interface.c | ||
| soft-interface.h | ||
| sysfs.c | ||
| sysfs.h | ||
| tp_meter.c | ||
| tp_meter.h | ||
| translation-table.c | ||
| translation-table.h | ||
| tvlv.c | ||
| tvlv.h | ||
| types.h | ||