Otherwise fragmented CREATE_CHILD_SA exchanges won't get accepted
because they don't contain an SA payload.
It also prevents a warning when ordering payloads.
Fixes#752.
The maximum for IKEv1 is already 255 due to the 8-bit fragment number.
With an overhead of 17 bytes (x64) per fragment and a default maximum
of 10000 bytes per packet the maximum memory required is 14 kB
for a fragmented message.
We don't expect a response with the same MID, but apparently some
devices (e.g. FRITZ!Box) do that for DPDs, while still treating the
response as a new exchange. By storing the last message block as IV
we can't decrypt the first block of such a response.
Fixes#661.
While the examples in RFC 2408 show proposal numbers starting at 1 and
increasing by one for each subsequent proposal this is not mandatory.
Actually, IKEv1 proposals may start at any number, the only requirement
is that the proposal numbers increase monotonically they don't have to
do so consecutively.
Most implementations follow the examples and start numbering at 1 (charon,
racoon, Shrew, Cisco, Windows XP, FRITZ!Box) but pluto was one of the
implementations that started with 0 and there might be others out there.
The previous assumption that implementations always start numbering proposals
at 0 caused problems with clients that start numbering with 1 and whose first
proposal consists of multiple protocols (e.g. ESP+IPComp).
Fixes#661.
Even in Main Mode, some Sonicwall boxes seem to send ID/HASH payloads in
unencrypted form, probably to allow PSK lookup based on the ID payloads. We
by default reject that, but accept it if the
charon.accept_unencrypted_mainmode_messages option is set in strongswan.conf.
Initial patch courtesy of Paul Stewart.
This required some refactoring when handling encrypted payloads.
Also changed log messages so that "encrypted payload" is logged instead
of "encryption payload" (even if we internally still call it that) as
that's the name used in RFC 5996.
There is no reason not to do so (RFC 5996 explicitly mentions multiple
CERTREQ payloads) and some implementations seem to use the same behavior
as had to be used with IKEv1 (i.e. each CA in its own CERTREQ payload).
Tobias Brunner