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

2 files changed, 1 insertions, 34 deletions

diff --git a/src/libcommon/gsm_data.c b/src/libcommon/gsm_data.c
index 7c717a40f..f6fde37bd 100644
--- a/src/libcommon/gsm_data.c
+++ b/src/libcommon/gsm_data.c
@@ -71,25 +71,6 @@ int gsm_bts_model_register(struct gsm_bts_model *model)
 	return 0;
 }
 
-/* Get reference to a neighbor cell on a given BCCH ARFCN */
-struct gsm_bts *gsm_bts_neighbor(const struct gsm_bts *bts,
-				 uint16_t arfcn, uint8_t bsic)
-{
-	struct gsm_bts *neigh;
-	/* FIXME: use some better heuristics here to determine which cell
-	 * using this ARFCN really is closest to the target cell.  For
-	 * now we simply assume that each ARFCN will only be used by one
-	 * cell */
-
-	llist_for_each_entry(neigh, &bts->network->bts_list, list) {
-		if (neigh->c0->arfcn == arfcn &&
-		    neigh->bsic == bsic)
-			return neigh;
-	}
-
-	return NULL;
-}
-
 const struct value_string bts_type_descs[_NUM_GSM_BTS_TYPE+1] = {
 	{ GSM_BTS_TYPE_UNKNOWN,		"Unknown BTS Type" },
 	{ GSM_BTS_TYPE_BS11,		"Siemens BTS (BS-11 or compatible)" },
@@ -210,19 +191,6 @@ int bts_gprs_mode_is_compat(struct gsm_bts *bts, enum bts_gprs_mode mode)
 	return 1;
 }
 
-struct gsm_meas_rep *lchan_next_meas_rep(struct gsm_lchan *lchan)
-{
-	struct gsm_meas_rep *meas_rep;
-
-	meas_rep = &lchan->meas_rep[lchan->meas_rep_idx];
-	memset(meas_rep, 0, sizeof(*meas_rep));
-	meas_rep->lchan = lchan;
-	lchan->meas_rep_idx = (lchan->meas_rep_idx + 1)
-					% ARRAY_SIZE(lchan->meas_rep);
-
-	return meas_rep;
-}
-
 int gsm_btsmodel_set_feature(struct gsm_bts_model *model, enum gsm_bts_features feat)
 {
 	OSMO_ASSERT(_NUM_BTS_FEAT < MAX_BTS_FEATURES);
@@ -322,7 +290,7 @@ struct gsm_bts *gsm_bts_alloc_register(struct gsm_network *net, enum gsm_bts_typ
 	bts->si_common.chan_desc.att = 1; /* attachment required */
 	bts->si_common.chan_desc.bs_pa_mfrms = RSL_BS_PA_MFRMS_5; /* paging frames */
 	bts->si_common.chan_desc.bs_ag_blks_res = 1; /* reserved AGCH blocks */
-	bts->si_common.chan_desc.t3212 = 5; /* Use 30 min periodic update interval as sane default */
+	bts->si_common.chan_desc.t3212 = net->t3212; /* Use network's current value */
 	gsm_bts_set_radio_link_timeout(bts, 32); /* Use RADIO LINK TIMEOUT of 32 */
 
 	llist_add_tail(&bts->list, &net->bts_list);
diff --git a/src/libcommon/talloc_ctx.c b/src/libcommon/talloc_ctx.c
index 5e3d9aebe..c8e9cd31d 100644
--- a/src/libcommon/talloc_ctx.c
+++ b/src/libcommon/talloc_ctx.c
@@ -44,7 +44,6 @@ void talloc_ctx_init(void *ctx_root)
 	tall_authciphop_ctx = talloc_named_const(ctx_root, 0, "auth_ciph_oper");
 	tall_gsms_ctx = talloc_named_const(ctx_root, 0, "sms");
 	tall_subscr_ctx = talloc_named_const(ctx_root, 0, "subscriber");
-	tall_sub_req_ctx = talloc_named_const(ctx_root, 0, "subscr_request");
 	tall_call_ctx = talloc_named_const(ctx_root, 0, "gsm_call");
 	tall_paging_ctx = talloc_named_const(ctx_root, 0, "paging_request");
 	tall_sigh_ctx = talloc_named_const(ctx_root, 0, "signal_handler");