Add libvlr implementation

Original libvlr code is by Harald Welte <laforge@gnumonks.org>,
polished and tweaked by Neels Hofmeyr <nhofmeyr@sysmocom.de>.

This is a long series of trial-and-error development collapsed in one patch.
This may be split in smaller commits if reviewers prefer that. If we can keep
it as one, we have saved ourselves the additional separation work.

Related: OS#1592
Change-Id: Ie303c98f8c18e40c87c1b68474b35de332033622

1 files changed, 269 insertions, 0 deletions

diff --git a/src/libmsc/subscr_conn.c b/src/libmsc/subscr_conn.c
new file mode 100644
index 000000000..91ffe4069
--- /dev/null
+++ b/src/libmsc/subscr_conn.c
@@ -0,0 +1,269 @@
+/* MSC subscriber connection implementation */
+
+/*
+ * (C) 2016 by sysmocom s.m.f.c. <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/fsm.h>
+
+#include <openbsc/osmo_msc.h>
+#include <openbsc/vlr.h>
+#include <openbsc/debug.h>
+#include <openbsc/transaction.h>
+
+static const struct value_string subscr_conn_fsm_event_names[] = {
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_INVALID),
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_ACCEPTED),
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_BUMP),
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_MO_CLOSE),
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_CN_CLOSE),
+	OSMO_VALUE_STRING(SUBSCR_CONN_E_CLOSE_CONF),
+	{ 0, NULL }
+};
+
+const struct value_string subscr_conn_from_names[] = {
+	OSMO_VALUE_STRING(SUBSCR_CONN_FROM_INVALID),
+	OSMO_VALUE_STRING(SUBSCR_CONN_FROM_LU),
+	OSMO_VALUE_STRING(SUBSCR_CONN_FROM_CM_SERVICE_REQ),
+	OSMO_VALUE_STRING(SUBSCR_CONN_FROM_PAGING_RESP),
+	{ 0, NULL }
+};
+
+static void paging_resp(struct gsm_subscriber_connection *conn,
+			       enum gsm_paging_event pe)
+{
+	subscr_paging_dispatch(GSM_HOOK_RR_PAGING, pe, NULL, conn, conn->subscr);
+}
+
+void subscr_conn_fsm_new(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct gsm_subscriber_connection *conn = fi->priv;
+	enum subscr_conn_from from = SUBSCR_CONN_FROM_INVALID;
+	enum gsm_paging_event pe;
+
+	if (data) {
+		from = *(enum subscr_conn_from*)data;
+		LOGPFSM(fi, "%s\n", subscr_conn_from_name(from));
+	}
+
+	/* If accepted, transition the state, all other cases mean failure. */
+	switch (event) {
+	case SUBSCR_CONN_E_ACCEPTED:
+		osmo_fsm_inst_state_chg(fi, SUBSCR_CONN_S_ACCEPTED, 0, 0);
+		break;
+
+	case SUBSCR_CONN_E_MO_CLOSE:
+	case SUBSCR_CONN_E_CN_CLOSE:
+	case SUBSCR_CONN_E_CLOSE_CONF:
+		break;
+
+	default:
+		LOGPFSM(fi, "Unexpected event: %d %s\n",
+			event, osmo_fsm_event_name(fi->fsm, event));
+		break;
+	}
+
+	/* if appropriate, signal paging success or failure */
+	if (from == SUBSCR_CONN_FROM_PAGING_RESP) {
+		pe = (fi->state == SUBSCR_CONN_S_ACCEPTED)?
+			GSM_PAGING_SUCCEEDED : GSM_PAGING_EXPIRED;
+		paging_resp(conn, pe);
+	}
+
+	/* On failure, discard the conn */
+	if (fi->state != SUBSCR_CONN_S_ACCEPTED) {
+		/* TODO: on MO_CLOSE or CN_CLOSE, first go to RELEASING and
+		 * await BSC confirmation? */
+		osmo_fsm_inst_state_chg(fi, SUBSCR_CONN_S_RELEASED, 0, 0);
+		return;
+	}
+
+	/* On success, handle pending requests and/or close conn */
+
+	if (from == SUBSCR_CONN_FROM_CM_SERVICE_REQ) {
+		conn->received_cm_service_request = true;
+		LOGPFSM(fi, "received_cm_service_request = true\n");
+	}
+
+	osmo_fsm_inst_dispatch(fi, SUBSCR_CONN_E_BUMP, data);
+}
+
+#if 0
+	case SUBSCR_CONN_E_PARQ_SUCCESS:
+		osmo_fsm_inst_state_chg(fi, SUBSCR_CONN_S_ACCEPTED, 0, 0);
+		accept_conn = true;
+		/* fall through */
+	case SUBSCR_CONN_E_PARQ_FAILURE:
+		parq_type = data ? *(enum vlr_parq_type*)data : VLR_PR_ARQ_T_INVALID;
+		switch (parq_type) {
+
+		case VLR_PR_ARQ_T_CM_SERV_REQ:
+			accept_conn = handle_cm_serv_result(fi, accept_conn);
+			break;
+
+		case VLR_PR_ARQ_T_PAGING_RESP:
+			accept_conn = handle_paging_result(fi, accept_conn);
+			break;
+
+		default:
+			LOGPFSML(fi, LOGL_ERROR,
+				 "Invalid VLR Process Access Request type"
+				 " %d\n", parq_type);
+			accept_conn = false;
+			break;
+		}
+		break;
+#endif
+
+static void subscr_conn_fsm_bump(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct gsm_subscriber_connection *conn = fi->priv;
+
+	if (conn->silent_call)
+		return;
+
+	if (conn->received_cm_service_request)
+		return;
+
+	/* is this needed? */
+	if (conn->subscr && !llist_empty(&conn->subscr->requests))
+		return;
+
+	if (trans_has_conn(conn))
+		return;
+
+	osmo_fsm_inst_state_chg(fi, SUBSCR_CONN_S_RELEASED, 0, 0);
+}
+
+static void subscr_conn_fsm_accepted(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case SUBSCR_CONN_E_BUMP:
+		subscr_conn_fsm_bump(fi, event, data);
+		return;
+
+	default:
+		break;
+	}
+	/* Whatever unexpected happens in the accepted state, it means release.
+	 * Even if an unexpected event is passed, the safest thing to do is
+	 * discard the conn. We don't expect another SUBSCR_CONN_E_ACCEPTED. */
+	osmo_fsm_inst_state_chg(fi, SUBSCR_CONN_S_RELEASED, 0, 0);
+}
+
+static void subscr_conn_fsm_release(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct gsm_subscriber_connection *conn = fi->priv;
+	if (!conn)
+		return;
+
+	/* temporary hack, see owned_by_msc */
+	if (!conn->owned_by_msc) {
+		DEBUGP(DMM, "%s leaving bsc_subscr_con_free() to bsc_api.c, owned_by_msc = false\n",
+		       subscr_name(conn->subscr));
+		return;
+	}
+
+	DEBUGP(DMM, "%s calling bsc_subscr_con_free(), owned_by_msc = true\n",
+	       subscr_name(conn->subscr));
+	gsm0808_clear(conn);
+	bsc_subscr_con_free(conn);
+}
+
+#define S(x)	(1 << (x))
+
+static const struct osmo_fsm_state subscr_conn_fsm_states[] = {
+	[SUBSCR_CONN_S_NEW] = {
+		.name = OSMO_STRINGIFY(SUBSCR_CONN_S_NEW),
+		.in_event_mask = S(SUBSCR_CONN_E_ACCEPTED) |
+				 S(SUBSCR_CONN_E_MO_CLOSE) |
+				 S(SUBSCR_CONN_E_CN_CLOSE) |
+				 S(SUBSCR_CONN_E_CLOSE_CONF),
+		.out_state_mask = S(SUBSCR_CONN_S_ACCEPTED) |
+				  S(SUBSCR_CONN_S_RELEASED),
+		.action = subscr_conn_fsm_new,
+	},
+	[SUBSCR_CONN_S_ACCEPTED] = {
+		.name = OSMO_STRINGIFY(SUBSCR_CONN_S_ACCEPTED),
+		/* allow everything to release for any odd behavior */
+		.in_event_mask = S(SUBSCR_CONN_E_ACCEPTED) |
+				 S(SUBSCR_CONN_E_BUMP) |
+				 S(SUBSCR_CONN_E_MO_CLOSE) |
+				 S(SUBSCR_CONN_E_CN_CLOSE) |
+				 S(SUBSCR_CONN_E_CLOSE_CONF),
+		.out_state_mask = S(SUBSCR_CONN_S_RELEASED),
+		.action = subscr_conn_fsm_accepted,
+	},
+	[SUBSCR_CONN_S_RELEASED] = {
+		.name = OSMO_STRINGIFY(SUBSCR_CONN_S_RELEASED),
+		.onenter = subscr_conn_fsm_release,
+	},
+};
+
+static struct osmo_fsm subscr_conn_fsm = {
+	.name = "Subscr_Conn",
+	.states = subscr_conn_fsm_states,
+	.num_states = ARRAY_SIZE(subscr_conn_fsm_states),
+	.allstate_event_mask = 0,
+	.allstate_action = NULL,
+	.log_subsys = DVLR,
+	.event_names = subscr_conn_fsm_event_names,
+};
+
+int msc_create_conn_fsm(struct gsm_subscriber_connection *conn, const char *id)
+{
+	struct osmo_fsm_inst *fi;
+	OSMO_ASSERT(conn);
+
+	if (conn->conn_fsm) {
+		LOGP(DMM, LOGL_ERROR,
+		     "%s: Error: connection already in use\n", id);
+		return -EINVAL;
+	}
+
+	fi = osmo_fsm_inst_alloc(&subscr_conn_fsm, conn, conn, LOGL_DEBUG, id);
+
+	if (!fi) {
+		LOGP(DMM, LOGL_ERROR,
+		     "%s: Failed to allocate subscr conn master FSM\n", id);
+		return -ENOMEM;
+	}
+	conn->conn_fsm = fi;
+	return 0;
+}
+
+bool msc_subscr_conn_is_accepted(struct gsm_subscriber_connection *conn)
+{
+	if (!conn)
+		return false;
+	if (!conn->subscr)
+		return false;
+	if (!conn->conn_fsm)
+		return false;
+	if (conn->conn_fsm->state != SUBSCR_CONN_S_ACCEPTED)
+		return false;
+	return true;
+}
+
+void msc_subscr_conn_init(void)
+{
+	osmo_fsm_register(&subscr_conn_fsm);
+}