Implement AoIP, port to M3UA SIGTRAN (large addition and refactoring)

This was originally a long series of commits converging to the final result
seen in this patch. It does not make much sense to review the smaller steps'
trial and error, we need to review this entire change as a whole.

Implement AoIP in osmo-msc and osmo-bsc.

Change over to the new libosmo-sigtran API with support for proper
SCCP/M3UA/SCTP stacking, as mandated by 3GPP specifications for the IuCS and
IuPS interfaces.

From here on, a separate osmo-stp process is required for SCCP routing between
OsmoBSC / OsmoHNBGW <-> OsmoMSC / OsmoSGSN

jenkins.sh: build from libosmo-sccp and osmo-iuh master branches now for new
M3UA SIGTRAN.

Patch-by: pmaier, nhofmeyr, laforge
Change-Id: I5ae4e05ee7c57cad341ea5e86af37c1f6b0ffa77

3 files changed, 227 insertions, 0 deletions

diff --git a/src/libcommon-cs/Makefile.am b/src/libcommon-cs/Makefile.am
index f3921ba5f..21c27455d 100644
--- a/src/libcommon-cs/Makefile.am
+++ b/src/libcommon-cs/Makefile.am
@@ -16,5 +16,6 @@ AM_CFLAGS = \
 noinst_LIBRARIES = libcommon-cs.a
 
 libcommon_cs_a_SOURCES = \
+	a_reset.c \
 	common_cs.c \
 	common_cs_vty.c
diff --git a/src/libcommon-cs/a_reset.c b/src/libcommon-cs/a_reset.c
new file mode 100644
index 000000000..c0294c797
--- /dev/null
+++ b/src/libcommon-cs/a_reset.c
@@ -0,0 +1,224 @@
+/* (C) 2017 by sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * 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/utils.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/fsm.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <openbsc/debug.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+
+#define RESET_RESEND_INTERVAL 2	/* sec */
+#define RESET_RESEND_TIMER_NO 1234	/* FIXME: dig out the real timer number */
+#define BAD_CONNECTION_THRESOLD 3	/* connection failures */
+
+enum fsm_states {
+	ST_DISC,		/* Disconnected from remote end */
+	ST_CONN,		/* We have a confirmed connection */
+};
+
+static const struct value_string fsm_state_names[] = {
+	{ST_DISC, "ST_DISC (disconnected)"},
+	{ST_CONN, "ST_CONN (connected)"},
+	{0, NULL},
+};
+
+enum fsm_evt {
+	EV_RESET_ACK,		/* got reset acknowlegement from remote end */
+	EV_N_DISCONNECT,	/* lost a connection */
+	EV_N_CONNECT,		/* made a successful connection */
+};
+
+static const struct value_string fsm_evt_names[] = {
+	{EV_RESET_ACK, "EV_RESET_ACK"},
+	{EV_N_DISCONNECT, "EV_N_DISCONNECT"},
+	{EV_N_CONNECT, "EV_N_CONNECT"},
+	{0, NULL},
+};
+
+/* Disconnected state */
+static void fsm_disc_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)data;
+	OSMO_ASSERT(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) fsm-state (msc-reset): %s, fsm-event: %s\n", reset->name,
+	     get_value_string(fsm_state_names, ST_CONN), get_value_string(fsm_evt_names, event));
+
+	reset->conn_loss_counter = 0;
+	osmo_fsm_inst_state_chg(fi, ST_CONN, 0, 0);
+}
+
+/* Connected state */
+static void fsm_conn_cb(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)data;
+	OSMO_ASSERT(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) fsm-state (msc-reset): %s, fsm-event: %s\n", reset->name,
+	     get_value_string(fsm_state_names, ST_CONN), get_value_string(fsm_evt_names, event));
+
+	switch (event) {
+	case EV_N_DISCONNECT:
+		if (reset->conn_loss_counter >= BAD_CONNECTION_THRESOLD) {
+			LOGP(DMSC, LOGL_NOTICE, "(%s) SIGTRAN connection down, reconnecting...\n", reset->name);
+			osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+		} else
+			reset->conn_loss_counter++;
+		break;
+	case EV_N_CONNECT:
+		reset->conn_loss_counter = 0;
+		break;
+	}
+}
+
+/* Timer callback to retransmit the reset signal */
+static int fsm_reset_ack_timeout_cb(struct osmo_fsm_inst *fi)
+{
+	struct a_reset_ctx *reset = (struct a_reset_ctx *)fi->priv;
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset-ack timeout (T%i) in state %s, resending...\n", reset->name, fi->T,
+	     get_value_string(fsm_state_names, fi->state));
+
+	reset->cb(reset->priv);
+
+	osmo_fsm_inst_state_chg(fi, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+	return 0;
+}
+
+static struct osmo_fsm_state fsm_states[] = {
+	[ST_DISC] = {
+		     .in_event_mask = (1 << EV_RESET_ACK),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "DISC",
+		     .action = fsm_disc_cb,
+		     },
+	[ST_CONN] = {
+		     .in_event_mask = (1 << EV_N_DISCONNECT) | (1 << EV_N_CONNECT),
+		     .out_state_mask = (1 << ST_DISC) | (1 << ST_CONN),
+		     .name = "CONN",
+		     .action = fsm_conn_cb,
+		     },
+};
+
+/* State machine definition */
+static struct osmo_fsm fsm = {
+	.name = "FSM RESET",
+	.states = fsm_states,
+	.num_states = ARRAY_SIZE(fsm_states),
+	.log_subsys = DMSC,
+	.timer_cb = fsm_reset_ack_timeout_cb,
+};
+
+/* Create and start state machine which handles the reset/reset-ack procedure */
+struct a_reset_ctx *a_reset_alloc(const void *ctx, const char *name, void *cb, void *priv)
+{
+	OSMO_ASSERT(name);
+
+	struct a_reset_ctx *reset;
+
+	/* Register the fsm description (if not already done) */
+	if (osmo_fsm_find_by_name(fsm.name) != &fsm)
+		osmo_fsm_register(&fsm);
+
+	/* Allocate and configure a new fsm instance */
+	reset = talloc_zero(ctx, struct a_reset_ctx);
+	OSMO_ASSERT(reset);
+	reset->priv = priv;
+	reset->cb = cb;
+	strncpy(reset->name, name, sizeof(reset->name));
+	reset->conn_loss_counter = 0;
+	reset->fsm = osmo_fsm_inst_alloc(&fsm, NULL, NULL, LOGL_DEBUG, "FSM RESET INST");
+	OSMO_ASSERT(reset->fsm);
+	reset->fsm->priv = reset;
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset handler fsm created.\n", reset->name);
+
+	/* kick off reset-ack sending mechanism */
+	osmo_fsm_inst_state_chg(reset->fsm, ST_DISC, RESET_RESEND_INTERVAL, RESET_RESEND_TIMER_NO);
+
+	return reset;
+}
+
+/* Tear down state machine */
+void a_reset_free(struct a_reset_ctx *reset)
+{
+	OSMO_ASSERT(reset);
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_free(reset->fsm);
+	reset->fsm = NULL;
+
+	memset(reset, 0, sizeof(*reset));
+	talloc_free(reset);
+
+	LOGP(DMSC, LOGL_NOTICE, "(%s) reset handler fsm destroyed.\n", reset->name);
+}
+
+/* Confirm that we sucessfully received a reset acknowlege message */
+void a_reset_ack_confirm(struct a_reset_ctx *reset)
+{
+	OSMO_ASSERT(reset);
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_RESET_ACK, reset);
+}
+
+/* Report a failed connection */
+void a_reset_conn_fail(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, just drop the info */
+	if (!reset)
+		return;
+
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_N_DISCONNECT, reset);
+}
+
+/* Report a successful connection */
+void a_reset_conn_success(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, just drop the info */
+	if (!reset)
+		return;
+
+	OSMO_ASSERT(reset->fsm);
+
+	osmo_fsm_inst_dispatch(reset->fsm, EV_N_CONNECT, reset);
+}
+
+/* Check if we have a connection to a specified msc */
+bool a_reset_conn_ready(struct a_reset_ctx *reset)
+{
+	/* If no reset context is supplied, we assume that
+	 * the connection can't be ready! */
+	if (!reset)
+		return false;
+
+	OSMO_ASSERT(reset->fsm);
+	if (reset->fsm->state == ST_CONN)
+		return true;
+
+	return false;
+}
diff --git a/src/libcommon-cs/common_cs.c b/src/libcommon-cs/common_cs.c
index 99206c86c..d6dff95df 100644
--- a/src/libcommon-cs/common_cs.c
+++ b/src/libcommon-cs/common_cs.c
@@ -78,6 +78,8 @@ struct gsm_network *gsm_network_init(void *ctx,
 
 	net->dyn_ts_allow_tch_f = true;
 
+	INIT_LLIST_HEAD(&net->a.bscs);
+
 	return net;
 }