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, 59 insertions, 0 deletions

diff --git a/src/libcommon-cs/common_cs.c b/src/libcommon-cs/common_cs.c
index fc9caafa0..8e19bb2b8 100644
--- a/src/libcommon-cs/common_cs.c
+++ b/src/libcommon-cs/common_cs.c
@@ -56,6 +56,9 @@ struct gsm_network *gsm_network_init(void *ctx,
 	net->country_code = country_code;
 	net->network_code = network_code;
 
+	/* Use 30 min periodic update interval as sane default */
+	net->t3212 = 5;
+
 	INIT_LLIST_HEAD(&net->trans_list);
 	INIT_LLIST_HEAD(&net->upqueue);
 	INIT_LLIST_HEAD(&net->subscr_conns);
@@ -107,6 +110,30 @@ struct msgb *gsm48_create_loc_upd_rej(uint8_t cause)
 	return msg;
 }
 
+int gsm48_extract_mi(uint8_t *classmark2_lv, int length, char *mi_string, uint8_t *mi_type)
+{
+	/* Check the size for the classmark */
+	if (length < 1 + *classmark2_lv)
+		return -1;
+
+	uint8_t *mi_lv = classmark2_lv + *classmark2_lv + 1;
+	if (length < 2 + *classmark2_lv + mi_lv[0])
+		return -2;
+
+	*mi_type = mi_lv[1] & GSM_MI_TYPE_MASK;
+	return gsm48_mi_to_string(mi_string, GSM48_MI_SIZE, mi_lv+1, *mi_lv);
+}
+
+int gsm48_paging_extract_mi(struct gsm48_pag_resp *resp, int length,
+			    char *mi_string, uint8_t *mi_type)
+{
+	static const uint32_t classmark_offset =
+		offsetof(struct gsm48_pag_resp, classmark2);
+	uint8_t *classmark2_lv = (uint8_t *) &resp->classmark2;
+	return gsm48_extract_mi(classmark2_lv, length - classmark_offset,
+				mi_string, mi_type);
+}
+
 uint8_t sms_next_rp_msg_ref(uint8_t *next_rp_ref)
 {
 	const uint8_t rp_msg_ref = *next_rp_ref;
diff --git a/src/libcommon-cs/common_cs_vty.c b/src/libcommon-cs/common_cs_vty.c
index 86b4c53e4..17916878b 100644
--- a/src/libcommon-cs/common_cs_vty.c
+++ b/src/libcommon-cs/common_cs_vty.c
@@ -284,6 +284,34 @@ DEFUN(cfg_net_no_timezone,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_net_per_loc_upd, cfg_net_per_loc_upd_cmd,
+      "periodic location update <6-1530>",
+      "Periodic Location Updating Interval\n"
+      "Periodic Location Updating Interval\n"
+      "Periodic Location Updating Interval\n"
+      "Periodic Location Updating Interval in Minutes\n")
+{
+	struct gsm_network *net = vty->index;
+
+	net->t3212 = atoi(argv[0]) / 6;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_net_no_per_loc_upd, cfg_net_no_per_loc_upd_cmd,
+      "no periodic location update",
+      NO_STR
+      "Periodic Location Updating Interval\n"
+      "Periodic Location Updating Interval\n"
+      "Periodic Location Updating Interval\n")
+{
+	struct gsm_network *net = vty->index;
+
+	net->t3212 = 0;
+
+	return CMD_SUCCESS;
+}
+
 static struct gsm_network *vty_global_gsm_network = NULL;
 
 /* initialize VTY elements used in both BSC and MSC */
@@ -293,6 +321,8 @@ int common_cs_vty_init(struct gsm_network *network,
 	OSMO_ASSERT(vty_global_gsm_network == NULL);
 	vty_global_gsm_network = network;
 
+	osmo_stats_vty_add_cmds();
+
 	install_element(CONFIG_NODE, &cfg_net_cmd);
 	install_node(&net_node, config_write_net);
 	vty_install_default(GSMNET_NODE);
@@ -310,6 +340,8 @@ int common_cs_vty_init(struct gsm_network *network,
 	install_element(GSMNET_NODE, &cfg_net_timezone_cmd);
 	install_element(GSMNET_NODE, &cfg_net_timezone_dst_cmd);
 	install_element(GSMNET_NODE, &cfg_net_no_timezone_cmd);
+	install_element(GSMNET_NODE, &cfg_net_per_loc_upd_cmd);
+	install_element(GSMNET_NODE, &cfg_net_no_per_loc_upd_cmd);
 	install_element(GSMNET_NODE, &cfg_net_dyn_ts_allow_tch_f_cmd);
 
 	return CMD_SUCCESS;