Add new 'osmo_ss7' SS7 core code with M3UA, ASP/AS FSM, ...

This is what aims to be a rather complete/proper implementation of the
SIGTRAN + SS7 protocol suite.  It has proper abstraction between the
layers with primitives, finite state machines for things like the AS and
ASP state machines, support for point code routing, etc.

What's not implemented at this point:
* re-integration of pre-existing SUA (pending)
* actual MTP2 and physical E1/T1 link support
* different trafic modes like broadcast/fail-over/load-balance

Change-Id: I375eb80f01acc013094851d91d1d3333ebc12bc7

1 files changed, 308 insertions, 0 deletions

diff --git a/src/xua_as_fsm.c b/src/xua_as_fsm.c
new file mode 100644
index 0000000..887a9ec
--- /dev/null
+++ b/src/xua_as_fsm.c
@@ -0,0 +1,308 @@
+/* SCCP M3UA / SUA AS osmo_fsm according to RFC3868 4.3.1 / RFC4666 4.3.2 */
+/* (C) Copyright 2017 by Harald Welte <laforge@gnumonks.org>
+ * 
+ * All Rights reserved.
+ *
+ * Based on Erlang implementation xua_as_fsm.erl in osmo-ss7.git
+ */
+
+#include <string.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/fsm.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/prim.h>
+#include <osmocom/core/logging.h>
+
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/sigtran_sap.h>
+#include <osmocom/sigtran/xua_msg.h>
+#include <osmocom/sigtran/protocol/sua.h>
+#include <osmocom/sigtran/protocol/m3ua.h>
+
+#include "xua_asp_fsm.h"
+#include "xua_as_fsm.h"
+#include "xua_internal.h"
+
+static struct msgb *encode_notify(const struct m3ua_notify_params *npar)
+{
+	struct xua_msg *xua = m3ua_encode_notify(npar);
+	struct msgb *msg = xua_to_msg(M3UA_VERSION, xua);
+	xua_msg_free(xua);
+	return msg;
+}
+
+static int asp_notify_all_as(struct osmo_ss7_as *as, struct m3ua_notify_params *npar)
+{
+	struct msgb *msg;
+	unsigned int i, sent = 0;
+
+	/* iterate over all non-DOWN ASPs and send them the message */
+	for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
+		struct osmo_ss7_asp *asp = as->cfg.asps[i];
+
+		if (!asp)
+			continue;
+
+		if (!asp->fi || asp->fi->state == XUA_ASP_S_DOWN)
+			continue;
+
+		/* Optional: ASP Identifier (if sent in ASP-UP) */
+		if (asp->asp_id_present) {
+			npar->presence |= NOTIFY_PAR_P_ASP_ID;
+			npar->asp_id = asp->asp_id;
+		} else
+			npar->presence &= ~NOTIFY_PAR_P_ASP_ID;
+
+		/* TODO: Optional Routing Context */
+
+		msg = encode_notify(npar);
+		osmo_ss7_asp_send(asp, msg);
+		sent++;
+	}
+
+	return sent;
+}
+
+
+/***********************************************************************
+ * Actual FSM
+ ***********************************************************************/
+
+#define S(x)	(1 << (x))
+
+enum xua_as_state {
+	XUA_AS_S_DOWN,
+	XUA_AS_S_INACTIVE,
+	XUA_AS_S_ACTIVE,
+	XUA_AS_S_PENDING,
+};
+
+static const struct value_string xua_as_event_names[] = {
+	{ XUA_ASPAS_ASP_INACTIVE_IND, 	"ASPAS-ASP_INACTIVE.ind" },
+	{ XUA_ASPAS_ASP_DOWN_IND,	"ASPAS-ASP_DOWN.ind" },
+	{ XUA_ASPAS_ASP_ACTIVE_IND,	"ASPAS-ASP_ACTIVE.ind" },
+	{ 0, NULL }
+};
+
+struct xua_as_fsm_priv {
+	struct osmo_ss7_as *as;
+};
+
+/* is any other ASP in this AS in state != DOWN? */
+static bool check_any_other_asp_not_down(struct osmo_ss7_as *as, struct osmo_ss7_asp *asp_cmp)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
+		struct osmo_ss7_asp *asp = as->cfg.asps[i];
+		if (!asp)
+			continue;
+
+		if (asp_cmp == asp)
+			continue;
+
+		if (asp->fi && asp->fi->state != XUA_ASP_S_DOWN)
+			return true;
+	}
+
+	return false;
+}
+
+/* is any other ASP in this AS in state ACTIVE? */
+static bool check_any_other_asp_in_active(struct osmo_ss7_as *as, struct osmo_ss7_asp *asp_cmp)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
+		struct osmo_ss7_asp *asp = as->cfg.asps[i];
+		if (!asp)
+			continue;
+
+		if (asp_cmp == asp)
+			continue;
+
+		if (asp->fi && asp->fi->state == XUA_ASP_S_ACTIVE)
+			return true;
+	}
+
+	return false;
+}
+
+
+static void xua_as_fsm_down(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case XUA_ASPAS_ASP_INACTIVE_IND:
+		/* one ASP transitions into ASP-INACTIVE */
+		osmo_fsm_inst_state_chg(fi, XUA_AS_S_INACTIVE, 0, 0);
+		break;
+	case XUA_ASPAS_ASP_DOWN_IND:
+		/* ignore */
+		break;
+	}
+}
+
+/* onenter call-back responsible of transmitting NTFY to all ASPs in
+ * case of AS state changes */
+static void xua_as_fsm_onenter(struct osmo_fsm_inst *fi, uint32_t old_state)
+{
+	struct xua_as_fsm_priv *xafp = (struct xua_as_fsm_priv *) fi->priv;
+	struct m3ua_notify_params npar = {
+		.status_type = M3UA_NOTIFY_T_STATCHG,
+	};
+
+	switch (fi->state) {
+	case XUA_AS_S_INACTIVE:
+		npar.status_info = M3UA_NOTIFY_I_AS_INACT;
+		break;
+	case XUA_AS_S_ACTIVE:
+		npar.status_info = M3UA_NOTIFY_I_AS_ACT;
+		break;
+	case XUA_AS_S_PENDING:
+		npar.status_info = M3UA_NOTIFY_I_AS_PEND;
+		break;
+	default:
+		return;
+	}
+
+	asp_notify_all_as(xafp->as, &npar);
+};
+
+static void xua_as_fsm_inactive(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct xua_as_fsm_priv *xafp = (struct xua_as_fsm_priv *) fi->priv;
+	struct osmo_ss7_asp *asp = data;
+
+	switch (event) {
+	case XUA_ASPAS_ASP_DOWN_IND:
+		/* one ASP transitions into ASP-DOWN */
+		if (check_any_other_asp_not_down(xafp->as, asp)) {
+			/* ignore, we stay AS_INACTIVE */
+		} else
+			osmo_fsm_inst_state_chg(fi, XUA_AS_S_DOWN, 0, 0);
+		break;
+	case XUA_ASPAS_ASP_ACTIVE_IND:
+		/* one ASP transitions into ASP-ACTIVE */
+		osmo_fsm_inst_state_chg(fi, XUA_AS_S_ACTIVE, 0, 0);
+		break;
+	case XUA_ASPAS_ASP_INACTIVE_IND:
+		/* ignore */
+		break;
+	}
+}
+
+static void xua_as_fsm_active(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct xua_as_fsm_priv *xafp = (struct xua_as_fsm_priv *) fi->priv;
+	struct osmo_ss7_asp *asp = data;
+
+	switch (event) {
+	case XUA_ASPAS_ASP_DOWN_IND:
+	case XUA_ASPAS_ASP_INACTIVE_IND:
+		if (check_any_other_asp_in_active(xafp->as, asp)) {
+			/* ignore, we stay AS_ACTIVE */
+		} else {
+			osmo_fsm_inst_state_chg(fi, XUA_AS_S_PENDING, 0, 0);
+			/* FIXME: Start T(r) */
+			/* FIXME: Queue all signalling messages until
+			 * recovery or T(r) expiry */
+		}
+		break;
+	case XUA_ASPAS_ASP_ACTIVE_IND:
+		/* ignore */
+		break;
+	}
+}
+
+static void xua_as_fsm_pending(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch (event) {
+	case XUA_ASPAS_ASP_ACTIVE_IND:
+		/* one ASP transitions into ASP-ACTIVE */
+		osmo_fsm_inst_state_chg(fi, XUA_AS_S_ACTIVE, 0, 0);
+		break;
+	case XUA_ASPAS_ASP_INACTIVE_IND:
+		/* ignore */
+		break;
+	case XUA_ASPAS_ASP_DOWN_IND:
+		/* ignore */
+		break;
+	}
+}
+
+static const struct osmo_fsm_state xua_as_fsm_states[] = {
+	[XUA_AS_S_DOWN] = {
+		.in_event_mask = S(XUA_ASPAS_ASP_INACTIVE_IND) |
+				 S(XUA_ASPAS_ASP_DOWN_IND),
+		.out_state_mask = S(XUA_AS_S_DOWN) |
+				  S(XUA_AS_S_INACTIVE),
+		.name = "AS_DOWN",
+		.action = xua_as_fsm_down,
+	},
+	[XUA_AS_S_INACTIVE] = {
+		.in_event_mask = S(XUA_ASPAS_ASP_DOWN_IND) |
+				 S(XUA_ASPAS_ASP_ACTIVE_IND) |
+				 S(XUA_ASPAS_ASP_INACTIVE_IND),
+		.out_state_mask = S(XUA_AS_S_DOWN) |
+				  S(XUA_AS_S_INACTIVE) |
+				  S(XUA_AS_S_ACTIVE),
+		.name = "AS_INACTIVE",
+		.action = xua_as_fsm_inactive,
+		.onenter = xua_as_fsm_onenter,
+	},
+	[XUA_AS_S_ACTIVE] = {
+		.in_event_mask = S(XUA_ASPAS_ASP_DOWN_IND) |
+				 S(XUA_ASPAS_ASP_INACTIVE_IND) |
+				 S(XUA_ASPAS_ASP_ACTIVE_IND),
+		.out_state_mask = S(XUA_AS_S_ACTIVE) |
+				  S(XUA_AS_S_PENDING),
+		.name = "AS_ACTIVE",
+		.action = xua_as_fsm_active,
+		.onenter = xua_as_fsm_onenter,
+	},
+	[XUA_AS_S_PENDING] = {
+		.in_event_mask = S(XUA_ASPAS_ASP_INACTIVE_IND) |
+				 S(XUA_ASPAS_ASP_DOWN_IND) |
+				 S(XUA_ASPAS_ASP_ACTIVE_IND),
+		.out_state_mask = S(XUA_AS_S_DOWN) |
+				  S(XUA_AS_S_INACTIVE) |
+				  S(XUA_AS_S_ACTIVE) |
+				  S(XUA_AS_S_PENDING),
+		.name = "AS_PENDING",
+		.action = xua_as_fsm_pending,
+		.onenter = xua_as_fsm_onenter,
+	},
+};
+
+struct osmo_fsm xua_as_fsm = {
+	.name = "XUA_AS",
+	.states = xua_as_fsm_states,
+	.num_states = ARRAY_SIZE(xua_as_fsm_states),
+	.log_subsys = DLSS7,
+	.event_names = xua_as_event_names,
+};
+
+/*! \brief Start an AS FSM for a given Application Server
+ *  \param[in] as Application Server for which to start the AS FSM
+ *  \param[in] log_level Logging level for logging of this FSM
+ *  \returns FSM instance in case of success; NULL in case of error */
+struct osmo_fsm_inst *xua_as_fsm_start(struct osmo_ss7_as *as, int log_level)
+{
+	struct osmo_fsm_inst *fi;
+	struct xua_as_fsm_priv *xafp;
+
+	fi = osmo_fsm_inst_alloc(&xua_as_fsm, as, NULL, log_level, as->cfg.name);
+
+	xafp = talloc_zero(fi, struct xua_as_fsm_priv);
+	if (!xafp) {
+		osmo_fsm_inst_term(fi, OSMO_FSM_TERM_ERROR, NULL);
+		return NULL;
+	}
+	xafp->as = as;
+
+	fi->priv = xafp;
+
+	return fi;
+}