mscsplit: various preparations to separate MSC from BSC

Disable large parts of the code that depend on BSC presence. The code sections
disabled by #if BEFORE_MSCSPLIT shall be modified or dropped in the course of
adding the A-interface.

Don't set msg->lchan nor msg->dst.
Don't use lchan in libmsc.
Decouple lac from bts.

Prepare entry/exit point for MSC -> BSC and MSC -> RNC communication:
Add msc_ifaces.[hc], a_iface.c, with a general msc_tx_dtap() to redirect to
different interfaces depending on the actual subscriber connection.
While iu_tx() is going to be functional fairly soon, the a_tx() is going to be
just a dummy for some time (see comment).
Add Iu specific fields in gsm_subscriber_connection: the UE connection pointer
and an indicator for the Integrity Protection status on Iu (to be fully
implemented in later commits).
Add lac member to gsm_subscriber_connection, to allow decoupling from
bts->location_area_code. The conn->lac will actually be set in iu.c in an
upcoming commit ("add iucs.[hc]").

move to libcommon-cs: gsm48_extract_mi(), gsm48_paging_extract_mi().

libmsc: duplicate gsm0808 / gsm48 functions (towards BSC).
In osmo-nitb, libmsc would directly call the functions on the BSC level, not
always via the bsc_api. When separating libmsc from libbsc, some functions are
missing from the linkage.
Hence duplicate these functions to libmsc, add an msc_ prefix for clarity, also
add a _tx to gsm0808_cipher_mode():
* add msc_gsm0808_tx_cipher_mode() (dummy/stub)
* add msc_gsm48_tx_mm_serv_ack()
* add msc_gsm48_tx_mm_serv_rej()
Call these from libmsc instead of
* gsm0808_cipher_mode()
* gsm48_tx_mm_serv_ack()
* gsm48_tx_mm_serv_rej()
Also add a comment related to msc_gsm0808_tx_cipher_mode() in two places.

Remove internal RTP streaming code; OsmoNITB supported that, but for OsmoMSC,
this will be done with an external MGCP gateway.

Remove LCHAN_MODIFY from internal MNCC state machine.

Temporarily disable all paging to be able to link libmsc without libbsc.
Skip the paging part of channel_test because the paging is now disabled.
Employ fake paging shims in order for msc_vlr_tests to still work.

msc_compl_l3(): publish in .h, tweak return value.  Use new libmsc enum values
for return val, to avoid dependency on libbsc headers.  Make callable from
other scopes: publish in osmo_msc.h and remove 'static' in osmo_msc.c

add gsm_encr to subscr_conn
move subscr_request to gsm_subscriber.h
subscr_request_channel() -> subscr_request_conn()
move to libmsc: osmo_stats_vty_add_cmds()
gsm_04_08: remove apply_codec_restrictions()
gsm0408_test: use NULL for root ctx
move to libbsc: gsm_bts_neighbor()
move to libbsc: lchan_next_meas_rep()
move vty config for t3212 to network level (periodic lu)
remove unneccessary linking from some tests
remove handle_abisip_signal()
abis_rsl.c: don't use libvlr from libbsc

gsm_subscriber_connection: put the LAC here, so that it is available without
accessing conn->bts. In bsc_api.c, place this lac in conn for the sake of
transition: Iu and A will use this new field to pass the LAC around, but in a
completely separate OsmoBSC this is not actually needed. It can be removed
again from osmo-bsc.git when the time has come.

Siemens MRPCI: completely drop sending the MRPCI messages for now, they shall
be added in osmo-bsc once the A-Interface code has settled. See OS#2389.

Related: OS#1845 OS#2257 OS#2389
Change-Id: Id3705236350d5f69e447046b0a764bbabc3d493c

1 files changed, 3 insertions, 46 deletions

diff --git a/src/libmsc/mncc_builtin.c b/src/libmsc/mncc_builtin.c
index 067cc92f8..ac6e7345d 100644
--- a/src/libmsc/mncc_builtin.c
+++ b/src/libmsc/mncc_builtin.c
@@ -65,21 +65,6 @@ static struct gsm_call *get_call_ref(uint32_t callref)
 	return NULL;
 }
 
-uint8_t mncc_codec_for_mode(int lchan_type)
-{
-	/* FIXME: check codec capabilities of the phone */
-
-	if (lchan_type != GSM_LCHAN_TCH_H)
-		return mncc_int.def_codec[0];
-	else
-		return mncc_int.def_codec[1];
-}
-
-static uint8_t determine_lchan_mode(struct gsm_mncc *setup)
-{
-	return mncc_codec_for_mode(setup->lchan_type);
-}
-
 /* on incoming call, look up database and send setup to remote subscr. */
 static int mncc_setup_ind(struct gsm_call *call, int msg_type,
 			  struct gsm_mncc *setup)
@@ -137,9 +122,7 @@ static int mncc_setup_ind(struct gsm_call *call, int msg_type,
 	/* modify mode */
 	memset(&mncc, 0, sizeof(struct gsm_mncc));
 	mncc.callref = call->callref;
-	mncc.lchan_mode = determine_lchan_mode(setup);
-	DEBUGP(DMNCC, "(call %x) Modify channel mode: %s\n", call->callref,
-	       get_value_string(gsm48_chan_mode_names, mncc.lchan_mode));
+	DEBUGP(DMNCC, "(call %x) Modify channel mode\n", call->callref);
 	mncc_tx_to_cc(call->net, MNCC_LCHAN_MODIFY, &mncc);
 
 	/* send setup to remote */
@@ -207,10 +190,6 @@ static int mncc_setup_cnf(struct gsm_call *call, int msg_type,
 	bridge.callref[1] = call->remote_ref;
 	DEBUGP(DMNCC, "(call %x) Bridging with remote.\n", call->callref);
 
-	/* in direct mode, we always have to bridge the channels */
-	if (ipacc_rtp_direct)
-		return mncc_tx_to_cc(call->net, MNCC_BRIDGE, &bridge);
-
 	/* proxy mode */
 	if (!net->handover.active) {
 		/* in the no-handover case, we can bridge, i.e. use
@@ -279,28 +258,6 @@ static int mncc_rel_cnf(struct gsm_call *call, int msg_type, struct gsm_mncc *re
 	return 0;
 }
 
-/* receiving a (speech) traffic frame from the BSC code */
-static int mncc_rcv_data(struct gsm_call *call, int msg_type,
-			 struct gsm_data_frame *dfr)
-{
-	struct gsm_trans *remote_trans;
-
-	remote_trans = trans_find_by_callref(call->net, call->remote_ref);
-
-	/* this shouldn't really happen */
-	if (!remote_trans || !remote_trans->conn) {
-		LOGP(DMNCC, LOGL_ERROR, "No transaction or transaction without lchan?!?\n");
-		return -EIO;
-	}
-
-	/* RTP socket of remote end has meanwhile died */
-	if (!remote_trans->conn->lchan->abis_ip.rtp_socket)
-		return -EIO;
-
-	return rtp_send_frame(remote_trans->conn->lchan->abis_ip.rtp_socket, dfr);
-}
-
-
 /* Internal MNCC handler input function (from CC -> MNCC -> here) */
 int int_mncc_recv(struct gsm_network *net, struct msgb *msg)
 {
@@ -346,7 +303,8 @@ int int_mncc_recv(struct gsm_network *net, struct msgb *msg)
 	}
 
 	if (mncc_is_data_frame(msg_type)) {
-		rc = mncc_rcv_data(call, msg_type, arg);
+		LOGP(DMNCC, LOGL_ERROR, "(call %x) Received data frame, which is not supported.\n",
+		     call->callref);
 		goto out_free;
 	}
 
@@ -364,7 +322,6 @@ int int_mncc_recv(struct gsm_network *net, struct msgb *msg)
 		break;
 	case MNCC_CALL_CONF_IND:
 		/* we now need to MODIFY the channel */
-		data->lchan_mode = determine_lchan_mode(data);
 		mncc_tx_to_cc(call->net, MNCC_LCHAN_MODIFY, data);
 		break;
 	case MNCC_ALERT_IND: