[mgcp] Add a simple mgcp gateway used for the BSC

The python script is a simple call-agent driving the
client. Currently it is sending a AuditEndpoint message
and is printing the result.

The bsc_mgcp.c is a standalone process that will implement
a MGCP Gateway for the MSC. On call handling the Call-Agent
will ask the Gateway to "CreateConnection" and then this
gateway needs to communicate with OpenBSC.

Currently CreateConnection,ModifiyConnection,DeleteConnection
and Endpoint auditing is implemented.

[mgcp] Send RSIP on start and on first receive of any message

Ignore the first request and send a RSIP. We do that because
we might tunnel UDP through some other things and have no direct
way to connect to the call-agent.
Also the transaction is not checked and we ignore the response
from the call-agent, actually we print the '200 ' or any other
value as unhandled...

[mgcp] Print the MGCP command next to the response code

This allows to see which commands were sent by the server

mgcp: Terminate it with a new line

[mgcp] Make number of endpoints static...

For now this is fixed to the number of endpoints as of the GSM
specification...

[mgcp] The endpoint names seem to be base 16... use strtoul to parse

Use strtoul to parse the base 16 number from the mgw string.

[mgcp] Log the endpoints as hex numbers...

[mgcp] Only send the RSIP on the first incoming message..

Remove call_agent option (also remove the number from the getopt
call).

[mgcp] Start couting at 1 for the mgcp

[mgcp] Slight attempt to improve the grammar of the strings

[mgcp] Share validation routines between DLCX and MDCX

[mgcp] Remove help for dead config options

[mgcp] Specify a different IN addr in the SDP records

In case of NAT traversal be able to listen on a given
interface (like 127.0.0.1) but claim to receive data
at the beginning of the tunnel.

[mgcp] Fix the static copy of the SDP file

WIP verify out factoring broken..

[mgcp] Introduce VTY to the mgcp for config file parsing...

Parse the MGCP config file via the VTY framework.

[mgcp] Handle SDP parameters through VTY..

Currently the payload type, name and rate can be specified
in the config file.

[mgcp] Add an option to bind all rtp ports early

This can be useful for testing and in deployment to make sure
no runtime resource limit can be hit.

[mgcp] Add some API doc comment

[mgcp] Convert the packets of the example server to ascii

This will allow to easily patch the call id... to run the
server in a loop and make it work with the mediagateway

[mgcp] Assign CI_UNUSED... to be more obvious...

[mgcp] Use DEBUG and not DEBUGPC and specially not printf

Improve the logging a bit in the mgcp

[mgcp] Change the fake server to change the call id

This assume the call-agent will just increment the id
as well.... this is true for our implementation

[mgcp] Generate the transaction id dynamically..

This way wireshark will be more happy about it...

[mgcp] Recognize responses from the network..

This is just recognizing the response code and
then is doing nothing with it. Also change the
script to generate response messages...

[mgcp] Improve debug messages for CRCX/MDCX..

Log on which ports the media gateway is listening
and where the other (server) gateway is located

1 files changed, 48 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/mgcp.h b/openbsc/include/openbsc/mgcp.h
new file mode 100644
index 000000000..fa6224c12
--- /dev/null
+++ b/openbsc/include/openbsc/mgcp.h
@@ -0,0 +1,48 @@
+/* A Media Gateway Control Protocol Media Gateway: RFC 3435 */
+
+/*
+ * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009 by on-waves.com
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+unsigned int rtp_base_port = 4000;
+
+/**
+ * Calculate the RTP audio port for the given multiplex
+ * and the direction. This allows a semi static endpoint
+ * to port calculation removing the need for the BSC
+ * and the MediaGateway to communicate.
+ *
+ * Port usage explained:
+ *       base + (multiplex * 2) + 0 == local port to wait for network packets
+ *       base + (multiplex * 2) + 1 == local port for rtcp
+ *
+ * The above port will receive packets from the BTS that need
+ * to be patched and forwarded to the network.
+ * The above port will receive packets from the network that
+ * need to be patched and forwarded to the BTS.
+ *
+ * We assume to have a static BTS IP address so we can differentiate
+ * network and BTS.
+ *
+ */
+int rtp_calculate_port(int multiplex, int base)
+{
+	return base + (multiplex * 2);
+}