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.
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.
In case we have a stale SCCP connection with an Endpoint that
we want to reassign...use the newest (last) occurence of that
as it is most likely the one we want to handle.
It was possible that the nat detected the core network
gateway as the bts just due being the first to send data
to the port. Fix it by setting a dummy bts_ip to force
the mgcp_network code to compare the in_addr.
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.
E.g. when the MGCP on the BSS is not responding we could block
all of our endpoints. As we are mostly in the middle and forward
bits we will happily reallocate the endpoints.
When not being able to allocate the msgb for the forwarded data
there is no point in keeping and preparing the transaction. So
we can move the msg creation a bit up and only do the allocations
after having done the msgb allocation.
When receiving a DLCX we will now delete the endpoint right away. This
means when a BSS does not respond to the DLCX our endpoint will not
be blocked. E.g. this could happen when the MGCP is restarting or
in similiar conditions. When the BSS is not responding we move the
burden up the chain to the CallAgent. We have to still keep track
of the transaction id and the bsc pointer to keep the mgcp forward
routine working.
This value is copied into the bts_audio_payload when allocating
a BTS MGCP endpoint. For the nat we have actually no interest in
patching MGCP messages. We will patch them to the network because
the code will do it anyway, we will not patch things back to the
BTS.
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.
Instead of checking the token for NULL we need to check if running
was set to null. Look at the data of the token and check if the line
was ending with a \r\n or \n and then when rewriting a line use that
line ending as well. Add a new test for that.
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.
Holger Hans Peter Freyther