guy 2003/04/19 19:21:18 CDT
Modified files:
. packet-ipv6.c packet-clnp.c
Log:
Use "fragment_add_check()" for IPv6 and CLNP reassembly. (Possibly an
issue for CLNP, with its 16-bit IDs, which could be duplicated in a
sufficiently large capture even if CLNP implementations don't
deliberately reuse IDs; less of an issue for IPv6, with its 32-bit IDs
and with its prohibition on reuse:
For every packet that is to be fragmented, the source node generates
an Identification value. The Identification must be different than
that of any other fragmented packet sent recently* with the same
Source Address and Destination Address. If a Routing header is
present, the Destination Address of concern is that of the final
destination.
* "recently" means within the maximum likely lifetime of a packet,
including transit time from source to destination and time spent
awaiting reassembly with other fragments of the same packet.
However, it is not required that a source node know the maximum
packet lifetime. Rather, it is assumed that the requirement can
be met by maintaining the Identification value as a simple, 32-
bit, "wrap-around" counter, incremented each time a packet must
be fragmented. It is an implementation choice whether to
maintain a single counter for the node or multiple counters,
e.g., one for each of the node's possible source addresses, or
one for each active (source address, destination address)
combination.
but perhaps we'll ultimately be able to get rid of the old
"fragment_add()" entirely and rename "fragment_add_check()" to
"fragment_add()").
Revision Changes Path
1.95 +5 -2 ethereal/packet-ipv6.c
1.71 +6 -3 ethereal/packet-clnp.c