* [B.A.T.M.A.N.] question about frag_can_reassemble()
@ 2012-03-30 20:02 ` Dan Carpenter
0 siblings, 0 replies; 4+ messages in thread
From: Dan Carpenter @ 2012-03-30 20:02 UTC (permalink / raw)
To: Sven Eckelmann; +Cc: netdev, b.a.t.m.a.n
Hi Sven,
I had a question about the code in frag_can_reassemble().
net/batman-adv/unicast.h
51
52 merged_size = (skb->len - sizeof(*unicast_packet)) * 2;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
53 merged_size += sizeof(struct unicast_packet) + uneven_correction;
54
55 return merged_size <= mtu;
56 }
Can the skb->len be less than sizeof(*unicast_packet) (ie 20 bytes)?
If "len" is less than 10 then we would return false but if it's
over 10 then we would return true. Roughly.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 4+ messages in thread* question about frag_can_reassemble()
@ 2012-03-30 20:02 ` Dan Carpenter
0 siblings, 0 replies; 4+ messages in thread
From: Dan Carpenter @ 2012-03-30 20:02 UTC (permalink / raw)
To: Sven Eckelmann
Cc: netdev-u79uwXL29TY76Z2rM5mHXA,
b.a.t.m.a.n-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r
Hi Sven,
I had a question about the code in frag_can_reassemble().
net/batman-adv/unicast.h
51
52 merged_size = (skb->len - sizeof(*unicast_packet)) * 2;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
53 merged_size += sizeof(struct unicast_packet) + uneven_correction;
54
55 return merged_size <= mtu;
56 }
Can the skb->len be less than sizeof(*unicast_packet) (ie 20 bytes)?
If "len" is less than 10 then we would return false but if it's
over 10 then we would return true. Roughly.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [B.A.T.M.A.N.] question about frag_can_reassemble()
2012-03-30 20:02 ` Dan Carpenter
@ 2012-03-31 8:52 ` Marek Lindner
-1 siblings, 0 replies; 4+ messages in thread
From: Marek Lindner @ 2012-03-31 8:52 UTC (permalink / raw)
To: b.a.t.m.a.n; +Cc: netdev, Dan Carpenter
Dan,
> I had a question about the code in frag_can_reassemble().
>
> net/batman-adv/unicast.h
> 51
> 52 merged_size = (skb->len - sizeof(*unicast_packet)) * 2;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 53 merged_size += sizeof(struct unicast_packet) +
> uneven_correction; 54
> 55 return merged_size <= mtu;
> 56 }
>
> Can the skb->len be less than sizeof(*unicast_packet) (ie 20 bytes)?
> If "len" is less than 10 then we would return false but if it's
> over 10 then we would return true. Roughly.
the calling function checks for an existing unicast header. The call tree
looks like this:
recv_ucast_frag_packet() -> route_unicast_packet() -> frag_can_reassemble()
The first function does a unicast length check by calling
check_unicast_packet(). As a result we ensure that we at least have the length
of the unicast header in our packet unless we overlooked something ?
Regards,
Marek
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: question about frag_can_reassemble()
@ 2012-03-31 8:52 ` Marek Lindner
0 siblings, 0 replies; 4+ messages in thread
From: Marek Lindner @ 2012-03-31 8:52 UTC (permalink / raw)
To: b.a.t.m.a.n-ZwoEplunGu2X36UT3dwllkB+6BGkLq7r
Cc: netdev-u79uwXL29TY76Z2rM5mHXA, Dan Carpenter
Dan,
> I had a question about the code in frag_can_reassemble().
>
> net/batman-adv/unicast.h
> 51
> 52 merged_size = (skb->len - sizeof(*unicast_packet)) * 2;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 53 merged_size += sizeof(struct unicast_packet) +
> uneven_correction; 54
> 55 return merged_size <= mtu;
> 56 }
>
> Can the skb->len be less than sizeof(*unicast_packet) (ie 20 bytes)?
> If "len" is less than 10 then we would return false but if it's
> over 10 then we would return true. Roughly.
the calling function checks for an existing unicast header. The call tree
looks like this:
recv_ucast_frag_packet() -> route_unicast_packet() -> frag_can_reassemble()
The first function does a unicast length check by calling
check_unicast_packet(). As a result we ensure that we at least have the length
of the unicast header in our packet unless we overlooked something ?
Regards,
Marek
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-03-30 20:02 [B.A.T.M.A.N.] question about frag_can_reassemble() Dan Carpenter
2012-03-30 20:02 ` Dan Carpenter
2012-03-31 8:52 ` [B.A.T.M.A.N.] " Marek Lindner
2012-03-31 8:52 ` Marek Lindner
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