gsm_call_fsm: Implement classic MNCC_BRIDGE mode

In the classic MNCC_BRIDGE mode we ask the MSC to bridge the two
traffic channels itself.  This works for E1 as well as for RTP
BTSs', and even accross mixed E1 and RTP environments.

gsm_call_fsm.py

@@ -14,7 +14,9 @@ import ctypes
 import pykka
 
 from fysom import Fysom
-from mncc_sock import mncc_msg, mncc_number, mncc_rtp_msg
+from mncc_sock import mncc_msg, mncc_number, mncc_rtp_msg, mncc_bridge_msg
+
+Uint32Array2 = mncc.uint32_t * 2
 
 class GsmCallFsm(pykka.ThreadingActor):
     last_callref = 0
@@ -35,6 +37,13 @@ class GsmCallFsm(pykka.ThreadingActor):
                        called = mncc_number(self.called))
         self.mncc_ref.tell({'type': 'send', 'msg': msg})
 
+    def _onmncc_call_conf_ind(self, e):
+        msg_in = e.args[0]
+        for i in msg_in.bearer_cap.speech_ver:
+            print 'SPV: 0x%02x' % i,
+        msg = mncc_msg(msg_type = mncc.MNCC_LCHAN_MODIFY, callref = msg_in.callref, lchan_mode = 1)
+        self.mncc_ref.tell({'type': 'send', 'msg': msg})
+
     def _onmncc_setup_cnf(self, e):
         # send MNCC_SETUP_COMPL_REQ to MNCC interface, causing
         # CC-CONNECT-ACK to be sent to MS
@@ -106,6 +115,7 @@ class GsmCallFsm(pykka.ThreadingActor):
                     ('mncc_rel_cnf', 'RELEASE_REQUEST', 'NULL'),
                     ],
             callbacks = [('onmncc_setup_req', self._onmncc_setup_req),
+                         ('onmncc_call_conf_ind', self._onmncc_call_conf_ind),
                          ('onmncc_setup_cnf', self._onmncc_setup_cnf),
                          ('onmncc_disc_ind', self._onmncc_disc_ind),
                          ('onenterNULL', self._onenter_NULL),
@@ -249,14 +259,21 @@ class GsmCallConnector(pykka.ThreadingActor):
             self.call_a.tell({'type':'connect_rtp', 'rtp':self.rtp_b})
             self.call_b.tell({'type':'connect_rtp', 'rtp':self.rtp_a})
 
+    def bridge_legs(self):
+        # bridge the voice channels of both call legs in the classic way
+        if self.rtp_bridge:
+            raise Exception('GsmCallConnector', 'bridge_legs but in RTP bridge mode')
+        msg = mncc_bridge_msg(msg_type = mncc.MNCC_BRIDGE, callref = Uint32Array2(self.callref_a, self.callref_b))
+        self.mncc_act.tell({'type': 'send', 'msg': msg})
+
     def call_state_change(self, msisdn, old_state, new_state):
         print 'CallConnector:leg_state_change(%s) %s -> %s' % (msisdn, old_state, new_state)
         if msisdn == self.msisdn_a:     # A->B leg
             self.state_a = new_state
         elif msisdn == self.msisdn_b:   # B->A leg
             self.state_b = new_state
-        #if self.rtp_bridge == False and self.state_a == 'ACTIVE' and self.state_b == 'ACTIVE':
-        #    self.connect_legs()
+        if self.rtp_bridge == False and self.state_a == 'ACTIVE' and self.state_b == 'ACTIVE':
+            self.bridge_legs()
 
     def on_receive(self, message):
         if message['type'] == 'call_state_change':