common_vty.c was including bsc_nat.h which tried to
get the sccp/sccp_types.h which is not required to be
installed. Move all structs using/embedding SCCP structures
into the bsc_nat_sccp.h and include. This should fix
the compilation.
Inside the access-list we have a list of entries that have
either one allow or one deny rule... we do not allow to remove
a single rule but one has to remove the whole list, in that case
talloc will handle cleaning all entries.
Right now the matching is O(n*m) as we traverse the list
(multiple times) and run the regexp multiple times. One
way to make it faster would be to concat all regexps into
one.
One can set one access-list to one BSC and one
access-list to one NAT. The matching of IMSIs
remains the same for now, also applying the
white/blacklist. Access lists can not be deleted
for now and no perf opt is done (e.g. one could
cache the result of the last lookup in the bsc
struct).
We will need to confirm the connection, then we can send the
GSM48 message, then we need to close the connection... the
embedding in the refusal method was way too easy..
Right now it was not possible to just find a connection, by returning
the connection that is created we will have direct access to it. It
will be used by the local connection handling.
A local connection is only between the MUX and the real BSC. We will
not forward anything to the MSC. This will be needed for the IMSI
filtering as sending a CREF is not liked by every BSC...
For now we have:
1.) bsc imsi deny to deny at the BSC level
2.) bsc imsi allow to allow a SIM at the BSC level
3.) nat imsi deny to deny at the global level
We will send a ping every 20 seconds and if we have no pong
within 5 seconds we will close down the BSC connection and
wait for a reconnect. We will start this after having
authenticated the BSC and we stop the timer when destructing
the BSC connection.
Remember that we have seen a CC and have a valid destination
local reference now and only send a fake RLC to the MSC when
we had connections in this state.
When setting a new MSC timeslot to a SCCP connection check if
any of the existing connections have this timeslot, if so we will
send a DLCX down the stream to make sure it is closed there, when
we will CRCX this new timeslot we will happily reallocate it.
When the SCCP connection goes away, or we get a DLCX from the
network, or the BSC is gone we will send a DLCX message down the
stream as well.
When we receive a CRCX from the network we will forward the CRCX
as usual and send a dummy MDCX after it.
For the DLCX and the dummy MDCX we send a custom MGCP message
that will not provoke an answer. Even if the downstream MGCP GW
will answer we will ignore it due the dummy transaction id that
is not used anywhere else.
This change should make sure that we close the dowstream endpoint
all the time, even when the DLCX arrives after the SCCP connection
is torndown.
When sending a MSG to the MSC try to find the to be used "src" reference
by comparing the reference on the BSC and the BSC connection. Only this
tuple needs to be unique.
Actually only when looking at the SRC REF we need to compare the BSC as the
dest reference should be unique but we are just making the check a bit stronger
to make it look symmetric.
We will reset the multiplex in a DLCX message and then
we can reset the multiplex as well...even if the MGCP
connection is staying open. or at least this is a theory.
The MSC likes to leave a connection open during CallControl
when hanging up early enough in the process.
Count number of SCCP connections, number of BSC reconnects,
number of calls. For most of them we have a per BSC and a
global count.
Right now all structs using the counters survive until the
end of the application so we do not need to free them.
This method currently prepends the IPA header and sends
the data. In the future we might be able to use SCTP for
it.
We have to remove the IPA header from the static messages
for that to work.
This code is untested.
Remove the code to parse port as we need to discover the
BTS behind the nat and most likely it will have a different
port than the one advertised by the BTS.
This reverts commit c6a1fe773d.
The MGCP protocol parsing is adding '\0' to make sure we do not
parse beyond where we should parse. This does not mix with strtok
or similiar routines.
For now we will read the msg into a global array first, then copy
it to the msgb for mgcp protocol handling and if we are required
to forward it to the MGCP we have a untouched copy we will modify
into our own msgb.
Attempt to find the message by transaction id, then patch
the response and use the IP/PORT of the local network, update
the ci with the one from the BSC.
This is currently not tracking any state of the MGCP and will
not handle two bsc's... this will need to happen later.
With this in we should be feature complete and now enter the
mode of making all of this work reliable and fixing thinko's
and other bugs.
* Forward a rewritten msg to the BSS. We change the IP and port
to point to the NAT instead of the core network. We also keep
track of the BSC and the transacition id.
* Handle the case where we have not found a SCCP connection and
need to send a response ourselves.
Add code to change the ip and port for audio data inside
MGCP messages. This is needed because the BSS might be
behind the NAT and can not reach the network directly and
might be behind a nat so the announced sourceport is not
the one as we see it.
When losing the SCCP connection make sure that we free all
endpoints. The disconnection of the BSC should already make
sure they are closed but this makes sure everything is
properly reset.
For the nat we will have NAT and MGCP in the same process
and this commit starts with that. We are linking in the MGCP
code and one can embed MGCP config snippets...
* Return the SCCP connection. This will be needed to store the
assigned timeslot in there.
* Update code to work with this change
* This uncovered a bug in the CC handling, at the time the BSC was
passed it was still a null pointer and the code would have failed.
Moving it here means we can more easily test this code, there is one
behaviour change with the code that we only support paging messages
with one LAC and will silently ignore the others.
On a CC message we will need to remeber where the source local
reference of the network belonged so we can properly identify
the connection when receiving UDT messages.
Based on the token the NAT/MUX is capable of figuring out
which LAC this BSC is supposed to satisfy. This will be
needed for messages like paging that can be done by LAC.
* Create struct bsc_nat and move the various lists into this structure
* Create the VTY code
* Call the VTY init and parsing code
* Create functions to create the types..
* Add some stuff into the bsc_connection to be used for the NAT with
proper config files. E.g. to close the connection if the BSC does not
respond to a given command.
Introduce a bsc_nat_parse method to parse a IP Access method
into various parts. Write out the IPA Proto, in case SCCP is used,
store the msg type, pointers to the source/dest local reference and
other information.
Use the result of bsc_nat_parse inside the bsc_nat_filter method
to decide if the message should be dropped or not.
In the future the bsc_nat_parse result will be used for patching
SCCP references and other parts of the message.
The filter language should be able to filter the msg type of SCCP
messages and gain the "NOT" word in the filter language.
The first part is to analyze the IP Access Header and only forward
SCCP messages for now. In the future we might want to do MGCP
signalling through this protocol and connection as well and need to
update this then.
Holger Hans Peter Freyther