From ae361ce19fa135035c6b83ac1f07090b72fd4b8f Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Tue, 25 Jan 2011 22:02:31 +0000 Subject: batman-adv: Calculate correct size for merged packets The routing algorithm must be able to decide if a fragment can be merged with the missing part and still be passed to a forwarding interface. The fragments can only differ by one byte in case that the original payload had an uneven length. In that situation the sender has to inform all possible receivers that the tail is one byte longer using the flag UNI_FRAG_LARGETAIL. The combination of UNI_FRAG_LARGETAIL and UNI_FRAG_HEAD flag makes it possible to calculate the correct length for even and uneven sized payloads. The original formula missed to add the unicast header at all and forgot to remove the fragment header of the second fragment. This made the results highly unreliable and only useful for machines with large differences between the configured MTUs. Reported-by: Russell Senior Reported-by: Marek Lindner Signed-off-by: Sven Eckelmann --- net/batman-adv/packet.h | 1 + 1 file changed, 1 insertion(+) (limited to 'net/batman-adv/packet.h') diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h index 2284e8129cb..03ce0d314c9 100644 --- a/net/batman-adv/packet.h +++ b/net/batman-adv/packet.h @@ -50,6 +50,7 @@ /* fragmentation defines */ #define UNI_FRAG_HEAD 0x01 +#define UNI_FRAG_LARGETAIL 0x02 struct batman_packet { uint8_t packet_type; -- cgit v1.2.3-18-g5258