gprs_ns2: rework IP-SNS binds

Introduce a `ip-sns-bind BINDID` vty command within a `nse` vty object.
The ip-sns-bind defines the binds which will be used by the dynamic
configuration with IP-SNS.
This is only the first part which only uses the binds when doing a
new SNS configuration.
The outgoing add procedure will be supported in a later patch
when the SNS fsm supports outgoing procedures.

This is a behaviour change of the API and must be synchronized with
the osmo-pcu. Otherwise SNS won't work with osmo-pcu.

Related: SYS#5354
Change-Id: I9ab8092bf286e7d90e92f5702a5404425e959c84

6 files changed, 469 insertions, 37 deletions

diff --git a/include/osmocom/gprs/gprs_ns2.h b/include/osmocom/gprs/gprs_ns2.h
index b406bb0d..56a9b4f4 100644
--- a/include/osmocom/gprs/gprs_ns2.h
+++ b/include/osmocom/gprs/gprs_ns2.h
@@ -230,6 +230,8 @@ int gprs_ns2_sns_add_endpoint(struct gprs_ns2_nse *nse,
 				   const struct osmo_sockaddr *saddr);
 int gprs_ns2_sns_del_endpoint(struct gprs_ns2_nse *nse,
 				   const struct osmo_sockaddr *saddr);
+int gprs_ns2_sns_add_bind(struct gprs_ns2_nse *nse, struct gprs_ns2_vc_bind *bind);
+int gprs_ns2_sns_del_bind(struct gprs_ns2_nse *nse, struct gprs_ns2_vc_bind *bind);
 const struct osmo_sockaddr *gprs_ns2_nse_sns_remote(struct gprs_ns2_nse *nse);
 
 const struct osmo_sockaddr *gprs_ns2_ip_vc_remote(const struct gprs_ns2_vc *nsvc);
diff --git a/src/gb/gprs_ns2.c b/src/gb/gprs_ns2.c
index 9302a16f..bc4db53e 100644
--- a/src/gb/gprs_ns2.c
+++ b/src/gb/gprs_ns2.c
@@ -1269,6 +1269,7 @@ void gprs_ns2_start_alive_all_nsvcs(struct gprs_ns2_nse *nse)
 void gprs_ns2_free_bind(struct gprs_ns2_vc_bind *bind)
 {
 	struct gprs_ns2_vc *nsvc, *tmp;
+	struct gprs_ns2_nse *nse;
 	if (!bind)
 		return;
 
@@ -1276,6 +1277,12 @@ void gprs_ns2_free_bind(struct gprs_ns2_vc_bind *bind)
 		gprs_ns2_free_nsvc(nsvc);
 	}
 
+	if (gprs_ns2_is_ip_bind(bind)) {
+		llist_for_each_entry(nse, &bind->nsi->nse, list) {
+			gprs_ns2_sns_del_bind(nse, bind);
+		}
+	}
+
 	if (bind->driver->free_bind)
 		bind->driver->free_bind(bind);
 
diff --git a/src/gb/gprs_ns2_sns.c b/src/gb/gprs_ns2_sns.c
index ab8415df..dfa9afe2 100644
--- a/src/gb/gprs_ns2_sns.c
+++ b/src/gb/gprs_ns2_sns.c
@@ -81,6 +81,8 @@ enum gprs_sns_event {
 	GPRS_SNS_EV_CHANGE_WEIGHT,
 	GPRS_SNS_EV_NO_NSVC,
 	GPRS_SNS_EV_NSVC_ALIVE,		/*!< a NS-VC became alive */
+	GPRS_SNS_EV_REQ_ADD_BIND,
+	GPRS_SNS_EV_REQ_DELETE_BIND,
 };
 
 static const struct value_string gprs_sns_event_names[] = {
@@ -95,6 +97,8 @@ static const struct value_string gprs_sns_event_names[] = {
 	{ GPRS_SNS_EV_CHANGE_WEIGHT,	"CHANGE_WEIGHT" },
 	{ GPRS_SNS_EV_NO_NSVC,		"NO_NSVC" },
 	{ GPRS_SNS_EV_NSVC_ALIVE,	"NSVC_ALIVE"},
+	{ GPRS_SNS_EV_REQ_ADD_BIND,	"ADD_BIND"},
+	{ GPRS_SNS_EV_REQ_DELETE_BIND,	"DELETE_BIND"},
 	{ 0, NULL }
 };
 
@@ -103,6 +107,11 @@ struct sns_endpoint {
 	struct osmo_sockaddr saddr;
 };
 
+struct ns2_sns_bind {
+	struct llist_head list;
+	struct gprs_ns2_vc_bind *bind;
+};
+
 struct ns2_sns_state {
 	struct gprs_ns2_nse *nse;
 
@@ -110,6 +119,10 @@ struct ns2_sns_state {
 
 	/* holds the list of initial SNS endpoints */
 	struct llist_head sns_endpoints;
+	/* list of used struct ns2_sns_bind  */
+	struct llist_head binds;
+	/* pointer to the bind which was used to initiate the SNS connection */
+	struct ns2_sns_bind *initial_bind;
 	/* prevent recursive reselection */
 	bool reselection_running;
 
@@ -120,8 +133,6 @@ struct ns2_sns_state {
 	struct sns_endpoint *initial;
 	/* all SNS PDU will be sent over this nsvc */
 	struct gprs_ns2_vc *sns_nsvc;
-	/* iterate over the binds after all remote has been tested */
-	int bind_offset;
 	/* timer N */
 	int N;
 	/* true if at least one nsvc is alive */
@@ -718,7 +729,7 @@ static void ns2_sns_st_size_onenter(struct osmo_fsm_inst *fi, uint32_t old_state
 	struct gprs_ns_ie_ip4_elem *ip4_elems;
 	struct gprs_ns_ie_ip6_elem *ip6_elems;
 	struct gprs_ns2_vc_bind *bind;
-	struct gprs_ns2_inst *nsi = gss->nse->nsi;
+	struct ns2_sns_bind *sbind;
 	struct osmo_sockaddr *remote;
 	const struct osmo_sockaddr *sa;
 	struct osmo_sockaddr local;
@@ -741,23 +752,25 @@ static void ns2_sns_st_size_onenter(struct osmo_fsm_inst *fi, uint32_t old_state
 	remote = &gss->initial->saddr;
 
 	/* count how many bindings are available (only UDP binds) */
-	count = ns2_ip_count_bind(nsi, remote);
+	count = llist_count(&gss->binds);
 	if (count == 0) {
 		/* TODO: logging */
 		return;
 	}
 
-	bind = ns2_ip_get_bind_by_index(nsi, remote, gss->bind_offset);
-	if (!bind) {
-		if (gss->bind_offset) {
-			gss->bind_offset = 0;
-			bind = ns2_ip_get_bind_by_index(nsi, remote, gss->bind_offset);
+	/* take the first bind or take the next bind */
+	if (!gss->initial_bind) {
+		gss->initial_bind = llist_first_entry(&gss->binds, struct ns2_sns_bind, list);
+	} else {
+		if (gss->initial_bind->list.next != &gss->binds) {
+			gss->initial_bind = llist_entry(gss->initial_bind->list.next, struct ns2_sns_bind, list);
+		} else {
+			gss->initial_bind = llist_first_entry(&gss->binds, struct ns2_sns_bind, list);
 		}
-
-		if (!bind)
-			return;
 	}
 
+	bind = gss->initial_bind->bind;
+
 	/* setup the NSVC */
 	if (!gss->sns_nsvc) {
 		gss->sns_nsvc = ns2_ip_bind_connect(bind, gss->nse, remote);
@@ -773,11 +786,8 @@ static void ns2_sns_st_size_onenter(struct osmo_fsm_inst *fi, uint32_t old_state
 			return;
 
 		gss->ip4_local = ip4_elems;
-
-		llist_for_each_entry(bind, &nsi->binding, list) {
-			if (!gprs_ns2_is_ip_bind(bind))
-				continue;
-
+		llist_for_each_entry(sbind, &gss->binds, list) {
+			bind = sbind->bind;
 			sa = gprs_ns2_ip_bind_sockaddr(bind);
 			if (!sa)
 				continue;
@@ -813,10 +823,8 @@ static void ns2_sns_st_size_onenter(struct osmo_fsm_inst *fi, uint32_t old_state
 
 		gss->ip6_local = ip6_elems;
 
-		llist_for_each_entry(bind, &nsi->binding, list) {
-			if (!gprs_ns2_is_ip_bind(bind))
-				continue;
-
+		llist_for_each_entry(sbind, &gss->binds, list) {
+			bind = sbind->bind;
 			sa = gprs_ns2_ip_bind_sockaddr(bind);
 			if (!sa)
 				continue;
@@ -1409,6 +1417,8 @@ static void ns2_sns_st_all_action(struct osmo_fsm_inst *fi, uint32_t event, void
 {
 	struct ns2_sns_state *gss = (struct ns2_sns_state *) fi->priv;
 	struct gprs_ns2_nse *nse = nse_inst_from_fi(fi);
+	struct ns2_sns_bind *sbind;
+	struct gprs_ns2_vc *nsvc, *nsvc2;
 
 	/* reset when receiving GPRS_SNS_EV_NO_NSVC */
 	switch (event) {
@@ -1428,19 +1438,16 @@ static void ns2_sns_st_all_action(struct osmo_fsm_inst *fi, uint32_t event, void
 		ns2_clear_ipv46_entries(gss);
 
 		/* Choose the next sns endpoint. */
-		if (llist_empty(&gss->sns_endpoints)) {
+		if (llist_empty(&gss->sns_endpoints) || llist_empty(&gss->binds)) {
 			gss->initial = NULL;
 			ns2_prim_status_ind(gss->nse, NULL, 0, GPRS_NS2_AFF_CAUSE_SNS_NO_ENDPOINTS);
 			osmo_fsm_inst_state_chg(fi, GPRS_SNS_ST_UNCONFIGURED, 0, 3);
 			return;
 		} else if (!gss->initial) {
 			gss->initial = llist_first_entry(&gss->sns_endpoints, struct sns_endpoint, list);
-			gss->bind_offset = 0;
 		} else if (gss->initial->list.next == &gss->sns_endpoints) {
 			/* last entry, continue with first */
 			gss->initial = llist_first_entry(&gss->sns_endpoints, struct sns_endpoint, list);
-			gss->bind_offset++;
-			gss->bind_offset %= ns2_ip_count_bind(nse->nsi, &gss->initial->saddr);
 		} else {
 			/* next element is an entry */
 			gss->initial = llist_entry(gss->initial->list.next, struct sns_endpoint, list);
@@ -1449,6 +1456,50 @@ static void ns2_sns_st_all_action(struct osmo_fsm_inst *fi, uint32_t event, void
 		gss->reselection_running = false;
 		osmo_fsm_inst_state_chg(fi, GPRS_SNS_ST_SIZE, nse->nsi->timeout[NS_TOUT_TSNS_PROV], 1);
 		break;
+	case GPRS_SNS_EV_REQ_ADD_BIND:
+		sbind = data;
+		switch (fi->state) {
+		case GPRS_SNS_ST_UNCONFIGURED:
+			osmo_fsm_inst_dispatch(nse->bss_sns_fi, GPRS_SNS_EV_SELECT_ENDPOINT, NULL);
+			break;
+		case GPRS_SNS_ST_SIZE:
+			/* TODO: add the ip4 element to the list */
+			break;
+		case GPRS_SNS_ST_CONFIG_BSS:
+		case GPRS_SNS_ST_CONFIG_SGSN:
+		case GPRS_SNS_ST_CONFIGURED:
+			/* TODO: add to SNS-IP procedure queue & add nsvc() */
+			break;
+		}
+		break;
+	case GPRS_SNS_EV_REQ_DELETE_BIND:
+		sbind = data;
+		switch (fi->state) {
+		case GPRS_SNS_ST_UNCONFIGURED:
+			break;
+		case GPRS_SNS_ST_SIZE:
+			/* TODO: remove the ip4 element from the list */
+			llist_for_each_entry_safe(nsvc, nsvc2, &nse->nsvc, list) {
+				if (nsvc->bind == sbind->bind) {
+					gprs_ns2_free_nsvc(nsvc);
+				}
+			}
+			break;
+		case GPRS_SNS_ST_CONFIG_BSS:
+		case GPRS_SNS_ST_CONFIG_SGSN:
+		case GPRS_SNS_ST_CONFIGURED:
+			/* TODO: do an delete SNS-IP procedure */
+			/* TODO: remove the ip4 element to the list */
+			llist_for_each_entry_safe(nsvc, nsvc2, &nse->nsvc, list) {
+				if (nsvc->bind == sbind->bind) {
+					gprs_ns2_free_nsvc(nsvc);
+				}
+			}
+			break;
+		}
+		/* if this is the last bind, the free_nsvc() will trigger a reselection */
+		talloc_free(sbind);
+		break;
 	}
 }
 
@@ -1457,7 +1508,9 @@ static struct osmo_fsm gprs_ns2_sns_bss_fsm = {
 	.states = ns2_sns_bss_states,
 	.num_states = ARRAY_SIZE(ns2_sns_bss_states),
 	.allstate_event_mask = S(GPRS_SNS_EV_NO_NSVC) |
-			       S(GPRS_SNS_EV_SELECT_ENDPOINT),
+			       S(GPRS_SNS_EV_SELECT_ENDPOINT) |
+			       S(GPRS_SNS_EV_REQ_ADD_BIND) |
+			       S(GPRS_SNS_EV_REQ_DELETE_BIND),
 	.allstate_action = ns2_sns_st_all_action,
 	.cleanup = NULL,
 	.timer_cb = ns2_sns_fsm_bss_timer_cb,
@@ -1488,6 +1541,7 @@ struct osmo_fsm_inst *ns2_sns_bss_fsm_alloc(struct gprs_ns2_nse *nse,
 	fi->priv = gss;
 	gss->nse = nse;
 	INIT_LLIST_HEAD(&gss->sns_endpoints);
+	INIT_LLIST_HEAD(&gss->binds);
 
 	return fi;
 err:
@@ -1810,6 +1864,69 @@ void ns2_sns_notify_alive(struct gprs_ns2_nse *nse, struct gprs_ns2_vc *nsvc, bo
 	}
 }
 
+int gprs_ns2_sns_add_bind(struct gprs_ns2_nse *nse,
+			  struct gprs_ns2_vc_bind *bind)
+{
+	struct ns2_sns_state *gss;
+	struct ns2_sns_bind *tmp;
+
+	OSMO_ASSERT(nse->bss_sns_fi);
+	gss = nse->bss_sns_fi->priv;
+
+	if (!gprs_ns2_is_ip_bind(bind)) {
+		return -EINVAL;
+	}
+
+	if (!llist_empty(&gss->binds)) {
+		llist_for_each_entry(tmp, &gss->binds, list) {
+			if (tmp->bind == bind)
+				return -EALREADY;
+		}
+	}
+
+	tmp = talloc_zero(gss, struct ns2_sns_bind);
+	if (!tmp)
+		return -ENOMEM;
+	tmp->bind = bind;
+	llist_add_tail(&tmp->list, &gss->binds);
+
+	osmo_fsm_inst_dispatch(nse->bss_sns_fi, GPRS_SNS_EV_REQ_ADD_BIND, tmp);
+	return 0;
+}
+
+/* Remove a bind from the SNS. All assosiated NSVC must be removed. */
+int gprs_ns2_sns_del_bind(struct gprs_ns2_nse *nse,
+			     struct gprs_ns2_vc_bind *bind)
+{
+	struct ns2_sns_state *gss;
+	struct ns2_sns_bind *tmp, *tmp2;
+	bool found = false;
+
+	if (!nse->bss_sns_fi)
+		return -EINVAL;
+
+	gss = nse->bss_sns_fi->priv;
+	if (gss->initial_bind && gss->initial_bind->bind == bind) {
+		if (gss->initial_bind->list.prev == &gss->binds)
+			gss->initial_bind = NULL;
+		else
+			gss->initial_bind = llist_entry(gss->initial_bind->list.prev, struct ns2_sns_bind, list);
+	}
+
+	llist_for_each_entry_safe(tmp, tmp2, &gss->binds, list) {
+		if (tmp->bind == bind) {
+			llist_del(&tmp->list);
+			found = true;
+		}
+	}
+
+	if (!found)
+		return -ENOENT;
+
+	osmo_fsm_inst_dispatch(nse->bss_sns_fi, GPRS_SNS_EV_REQ_DELETE_BIND, tmp);
+	return 0;
+}
+
 /* Update SNS weights
  * \param[in] nsvc the NSVC which should be updated
  */
diff --git a/src/gb/gprs_ns2_vty.c b/src/gb/gprs_ns2_vty.c
index 7a6b3bae..01409bbf 100644
--- a/src/gb/gprs_ns2_vty.c
+++ b/src/gb/gprs_ns2_vty.c
@@ -58,6 +58,7 @@
 static struct gprs_ns2_inst *vty_nsi = NULL;
 static struct osmo_fr_network *vty_fr_network = NULL;
 static struct llist_head binds;
+static struct llist_head nses;
 
 struct vty_bind {
 	struct llist_head list;
@@ -70,6 +71,21 @@ struct vty_bind {
 	uint8_t ip_sns_data_weight;
 };
 
+struct vty_nse {
+	struct llist_head list;
+	uint16_t nsei;
+	/* list of binds which are valid for this nse. Only IP-SNS uses this
+	 * to allow `no listen ..` in the bind context. So "half" created binds are valid for
+	 * IP-SNS. This allows changing the bind ip without modifying all NSEs afterwards */
+	struct llist_head binds;
+};
+
+/* used by IP-SNS to connect multiple vty_nse_bind to a vty_nse */
+struct vty_nse_bind {
+	struct llist_head list;
+	struct vty_bind *vbind;
+};
+
 /* TODO: this should into osmo timer */
 static const struct value_string gprs_ns_timer_strs[] = {
 	{ 0, "tns-block" },
@@ -135,6 +151,94 @@ static void vty_bind_free(struct vty_bind *vbind)
 	talloc_free(vbind);
 }
 
+static struct vty_nse *vty_nse_by_nsei(uint16_t nsei)
+{
+	struct vty_nse *vnse;
+	llist_for_each_entry(vnse, &nses, list) {
+		if (vnse->nsei == nsei)
+			return vnse;
+	}
+	return NULL;
+}
+
+static struct vty_nse *vty_nse_alloc(uint16_t nsei)
+{
+	struct vty_nse *vnse = talloc_zero(vty_nsi, struct vty_nse);
+	if (!vnse)
+		return NULL;
+
+	vnse->nsei = nsei;
+	INIT_LLIST_HEAD(&vnse->binds);
+	llist_add(&vnse->list, &nses);
+	return vnse;
+}
+
+static void vty_nse_free(struct vty_nse *vnse)
+{
+	if (!vnse)
+		return;
+
+	llist_del(&vnse->list);
+	/* all vbind of the nse will be freed by talloc */
+	talloc_free(vnse);
+}
+
+static int vty_nse_add_vbind(struct vty_nse *vnse, struct vty_bind *vbind)
+{
+	struct vty_nse_bind *vnse_bind;
+
+	if (vbind->ll != GPRS_NS2_LL_UDP)
+		return -EINVAL;
+
+	llist_for_each_entry(vnse_bind, &vnse->binds, list) {
+		if (vnse_bind->vbind == vbind)
+			return -EALREADY;
+	}
+
+	vnse_bind = talloc(vnse, struct vty_nse_bind);
+	if (!vnse_bind)
+		return -ENOMEM;
+	vnse_bind->vbind = vbind;
+
+	llist_add_tail(&vnse_bind->list, &vnse->binds);
+	return 0;
+}
+
+static int vty_nse_remove_vbind(struct vty_nse *vnse, struct vty_bind *vbind)
+{
+	struct vty_nse_bind *vnse_bind, *tmp;
+	if (vbind->ll != GPRS_NS2_LL_UDP)
+		return -EINVAL;
+
+	llist_for_each_entry_safe(vnse_bind, tmp, &vnse->binds, list) {
+		if (vnse_bind->vbind == vbind) {
+			llist_del(&vnse_bind->list);
+			talloc_free(vnse_bind);
+		}
+	}
+
+	return -ENOENT;
+}
+
+/* check if the NSE still has SNS configuration */
+static bool vty_nse_check_sns(struct gprs_ns2_nse *nse) {
+	struct vty_nse *vnse = vty_nse_by_nsei(nse->nsei);
+
+	int count = gprs_ns2_sns_count(nse);
+	if (count > 0) {
+		 /* there are other sns endpoints */
+		return true;
+	}
+
+	if (!vnse)
+		return false;
+
+	if (llist_empty(&vnse->binds))
+		return false;
+
+	return true;
+}
+
 static struct cmd_node ns_node = {
 	L_NS_NODE,
 	"%s(config-ns)# ",
@@ -172,14 +276,26 @@ DEFUN(cfg_ns_nsei, cfg_ns_nsei_cmd,
       )
 {
 	struct gprs_ns2_nse *nse;
+	struct vty_nse *vnse;
 	uint16_t nsei = atoi(argv[0]);
+	bool free_vnse = false;
+
+	vnse = vty_nse_by_nsei(nsei);
+	if (!vnse) {
+		vnse = vty_nse_alloc(nsei);
+		if (!vnse) {
+			vty_out(vty, "Failed to create vty NSE!%s", VTY_NEWLINE);
+			return CMD_ERR_INCOMPLETE;
+		}
+		free_vnse = true;
+	}
 
 	nse = gprs_ns2_nse_by_nsei(vty_nsi, nsei);
 	if (!nse) {
 		nse = gprs_ns2_create_nse(vty_nsi, nsei, GPRS_NS2_LL_UNDEF, GPRS_NS2_DIALECT_UNDEF);
 		if (!nse) {
 			vty_out(vty, "Failed to create NSE!%s", VTY_NEWLINE);
-			return CMD_ERR_INCOMPLETE;
+			goto err;
 		}
 		nse->persistent = true;
 	}
@@ -187,13 +303,19 @@ DEFUN(cfg_ns_nsei, cfg_ns_nsei_cmd,
 	if (!nse->persistent) {
 		/* TODO: should the dynamic NSE removed? */
 		vty_out(vty, "A dynamic NSE with the specified NSEI already exists%s", VTY_NEWLINE);
-		return CMD_ERR_INCOMPLETE;
+		goto err;
 	}
 
 	vty->node = L_NS_NSE_NODE;
 	vty->index = nse;
 
 	return CMD_SUCCESS;
+
+err:
+	if (free_vnse)
+		talloc_free(vnse);
+
+	return CMD_ERR_INCOMPLETE;
 }
 
 DEFUN(cfg_no_ns_nsei, cfg_no_ns_nsei_cmd,
@@ -204,6 +326,7 @@ DEFUN(cfg_no_ns_nsei, cfg_no_ns_nsei_cmd,
       )
 {
 	struct gprs_ns2_nse *nse;
+	struct vty_nse *vnse;
 	uint16_t nsei = atoi(argv[0]);
 
 	nse = gprs_ns2_nse_by_nsei(vty_nsi, nsei);
@@ -219,6 +342,10 @@ DEFUN(cfg_no_ns_nsei, cfg_no_ns_nsei_cmd,
 
 	vty_out(vty, "Deleting NS Entity %u%s", nse->nsei, VTY_NEWLINE);
 	gprs_ns2_free_nse(nse);
+
+	vnse = vty_nse_by_nsei(nsei);
+	vty_nse_free(vnse);
+
 	return CMD_SUCCESS;
 }
 
@@ -394,11 +521,18 @@ static void config_write_nsvc(struct vty *vty, const struct gprs_ns2_vc *nsvc)
 static void _config_write_ns_nse(struct vty *vty, struct gprs_ns2_nse *nse)
 {
 	struct gprs_ns2_vc *nsvc;
+	struct vty_nse *vnse = vty_nse_by_nsei(nse->nsei);
+	struct vty_nse_bind *vbind;
+
+	OSMO_ASSERT(vnse);
 
 	vty_out(vty, " nse %u%s", nse->nsei, VTY_NEWLINE);
 	switch (nse->dialect) {
 	case GPRS_NS2_DIALECT_SNS:
 		ns2_sns_write_vty(vty, nse);
+		llist_for_each_entry(vbind, &vnse->binds, list) {
+			vty_out(vty, "  ip-sns-bind %s%s", vbind->vbind->name, VTY_NEWLINE);
+		}
 		break;
 	default:
 		llist_for_each_entry(nsvc, &nse->nsvc, list) {
@@ -472,7 +606,7 @@ DEFUN(cfg_ns_bind_listen, cfg_ns_bind_listen_cmd,
 {
 	struct vty_bind *vbind = vty->index;
 	struct gprs_ns2_vc_bind *bind;
-
+	int rc;
 	const char *addr_str = argv[0];
 	unsigned int port = atoi(argv[1]);
 	struct osmo_sockaddr_str sockaddr_str;
@@ -494,8 +628,9 @@ DEFUN(cfg_ns_bind_listen, cfg_ns_bind_listen_cmd,
 		return CMD_WARNING;
 	}
 
-	if (gprs_ns2_ip_bind(vty_nsi, vbind->name, &sockaddr, vbind->dscp, &bind) != 0) {
-		vty_out(vty, "Failed to create the bind!%s", VTY_NEWLINE);
+	rc = gprs_ns2_ip_bind(vty_nsi, vbind->name, &sockaddr, vbind->dscp, &bind);
+	if (rc != 0) {
+		vty_out(vty, "Failed to create the bind (rc %d)!%s", rc, VTY_NEWLINE);
 		return CMD_WARNING;
 	}
 
@@ -1320,7 +1455,6 @@ DEFUN(cfg_no_ns_nse_ip_sns_remote, cfg_no_ns_nse_ip_sns_remote_cmd,
 	struct osmo_sockaddr_str remote_str; /* argv[0] */
 	struct osmo_sockaddr remote;
 	uint16_t port = atoi(argv[1]);
-	int count;
 
 	if (nse->ll != GPRS_NS2_LL_UDP) {
 		vty_out(vty, "This NSE doesn't support UDP.%s", VTY_NEWLINE);
@@ -1347,12 +1481,9 @@ DEFUN(cfg_no_ns_nse_ip_sns_remote, cfg_no_ns_nse_ip_sns_remote_cmd,
 		return CMD_WARNING;
 	}
 
-	count = gprs_ns2_sns_count(nse);
-	if (count > 0) {
-		 /* there are other sns endpoints */
+	if (vty_nse_check_sns(nse)) {
+		 /* there is still sns configuration valid */
 		return CMD_SUCCESS;
-	} else if (count < 0) {
-		OSMO_ASSERT(0);
 	} else {
 		/* clean up nse to allow other nsvc commands */
 		osmo_fsm_inst_term(nse->bss_sns_fi, OSMO_FSM_TERM_REQUEST, NULL);
@@ -1364,6 +1495,175 @@ DEFUN(cfg_no_ns_nse_ip_sns_remote, cfg_no_ns_nse_ip_sns_remote_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_ns_nse_ip_sns_bind, cfg_ns_nse_ip_sns_bind_cmd,
+      "ip-sns-bind BINDID",
+      "IP SNS binds\n"
+      "A udp bind which this SNS will be used. The bind must be already exists. Can be given multiple times.\n")
+{
+	struct gprs_ns2_nse *nse = vty->index;
+	struct gprs_ns2_vc_bind *bind;
+	struct vty_bind *vbind;
+	struct vty_nse *vnse;
+	const char *name = argv[0];
+	bool ll_modified = false;
+	bool dialect_modified = false;
+	int rc;
+
+	if (nse->ll == GPRS_NS2_LL_UNDEF) {
+		nse->ll = GPRS_NS2_LL_UDP;
+		ll_modified = true;
+	}
+
+	if (nse->dialect == GPRS_NS2_DIALECT_UNDEF) {
+		char sns[16];
+		snprintf(sns, sizeof(sns), "NSE%05u-SNS", nse->nsei);
+		nse->bss_sns_fi = ns2_sns_bss_fsm_alloc(nse, sns);
+		if (!nse->bss_sns_fi)
+			goto err;
+		nse->dialect = GPRS_NS2_DIALECT_SNS;
+		dialect_modified = true;
+	}
+
+	if (nse->ll != GPRS_NS2_LL_UDP) {
+		vty_out(vty, "Can not mix NS-VC with different link layer%s", VTY_NEWLINE);
+		goto err;
+	}
+
+	if (nse->dialect != GPRS_NS2_DIALECT_SNS) {
+		vty_out(vty, "Can not mix NS-VC with different dialects%s", VTY_NEWLINE);
+		goto err;
+	}
+
+	vbind = vty_bind_by_name(name);
+	if (!vbind) {
+		vty_out(vty, "Can not find the given bind '%s'%s", name, VTY_NEWLINE);
+		goto err;
+	}
+
+	if (vbind->ll != GPRS_NS2_LL_UDP) {
+		vty_out(vty, "ip-sns-bind can only be used with UDP bind%s",
+			VTY_NEWLINE);
+		goto err;
+	}
+
+	/* the vnse has been created together when creating the nse node. The parent node should check this already! */
+	vnse = vty_nse_by_nsei(nse->nsei);
+	OSMO_ASSERT(vnse);
+
+	rc = vty_nse_add_vbind(vnse, vbind);
+	switch (rc) {
+	case 0:
+		break;
+	case -EALREADY:
+		vty_out(vty, "Failed to add ip-sns-bind %s already present%s", name, VTY_NEWLINE);
+		goto err;
+	case -ENOMEM:
+		vty_out(vty, "Failed to add ip-sns-bind %s out of memory%s", name, VTY_NEWLINE);
+		goto err;
+	default:
+		vty_out(vty, "Failed to add ip-sns-bind %s! %d%s", name, rc, VTY_NEWLINE);
+		goto err;
+	}
+
+	/* the bind might not yet created because "listen" is missing. */
+	bind = gprs_ns2_bind_by_name(vty_nsi, name);
+	if (!bind)
+		return CMD_SUCCESS;
+
+	rc = gprs_ns2_sns_add_bind(nse, bind);
+	switch (rc) {
+	case 0:
+		break;
+	case -EALREADY:
+		vty_out(vty, "Failed to add ip-sns-bind %s already present%s", name, VTY_NEWLINE);
+		goto err;
+	case -ENOMEM:
+		vty_out(vty, "Failed to add ip-sns-bind %s out of memory%s", name, VTY_NEWLINE);
+		goto err;
+	default:
+		vty_out(vty, "Failed to add ip-sns-bind %s! %d%s", name, rc, VTY_NEWLINE);
+		goto err;
+	}
+
+	return CMD_SUCCESS;
+err:
+	if (ll_modified)
+		nse->ll = GPRS_NS2_LL_UNDEF;
+	if (dialect_modified)
+		nse->dialect = GPRS_NS2_DIALECT_UNDEF;
+
+	return CMD_WARNING;
+}
+
+DEFUN(cfg_no_ns_nse_ip_sns_bind, cfg_no_ns_nse_ip_sns_bind_cmd,
+      "no ip-sns-bind BINDID",
+      NO_STR
+      "IP SNS binds\n"
+      "A udp bind which this SNS will be used.\n")
+{
+	struct gprs_ns2_nse *nse = vty->index;
+	struct gprs_ns2_vc_bind *bind;
+	struct vty_bind *vbind;
+	struct vty_nse *vnse;
+	const char *name = argv[0];
+	int rc;
+
+	if (nse->ll != GPRS_NS2_LL_UDP) {
+		vty_out(vty, "This NSE doesn't support UDP.%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (nse->dialect != GPRS_NS2_DIALECT_SNS) {
+		vty_out(vty, "This NSE doesn't support UDP with dialect ip-sns.%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	vbind = vty_bind_by_name(name);
+	if (!vbind) {
+		vty_out(vty, "Can not find the given bind '%s'%s", name, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (vbind->ll != GPRS_NS2_LL_UDP) {
+		vty_out(vty, "no ip-sns-bind can only be used with UDP bind%s",
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	/* the vnse has been created together when creating the nse node. The parent node should check this already! */
+	vnse = vty_nse_by_nsei(nse->nsei);
+	OSMO_ASSERT(vnse);
+
+	rc = vty_nse_remove_vbind(vnse, vbind);
+	switch(rc) {
+	case 0:
+		break;
+	case -ENOENT:
+		vty_out(vty, "Bind %s is not part of this NSE%s", name, VTY_NEWLINE);
+		return CMD_WARNING;
+	case -EINVAL:
+		vty_out(vty, "no ip-sns-bind can only be used with UDP bind%s",
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	default:
+		return CMD_WARNING;
+	}
+
+	/* the bind might not exists yet */
+	bind = gprs_ns2_bind_by_name(vty_nsi, name);
+	if (bind)
+		gprs_ns2_sns_del_bind(nse, bind);
+
+	if (!vty_nse_check_sns(nse)) {
+		/* clean up nse to allow other nsvc commands */
+		osmo_fsm_inst_term(nse->bss_sns_fi, OSMO_FSM_TERM_REQUEST, NULL);
+		nse->bss_sns_fi = NULL;
+		nse->ll = GPRS_NS2_LL_UNDEF;
+		nse->dialect = GPRS_NS2_DIALECT_UNDEF;
+	}
+
+	return CMD_SUCCESS;
+}
 
 /* non-config commands */
 static void dump_nsvc(struct vty *vty, struct gprs_ns2_vc *nsvc, bool stats)
@@ -1676,6 +1976,7 @@ int gprs_ns2_vty_init_reduced(struct gprs_ns2_inst *nsi)
 {
 	vty_nsi = nsi;
 	INIT_LLIST_HEAD(&binds);
+	INIT_LLIST_HEAD(&nses);
 
 	vty_fr_network = osmo_fr_network_alloc(nsi);
 	if (!vty_fr_network)
@@ -1737,6 +2038,8 @@ int gprs_ns2_vty_init(struct gprs_ns2_inst *nsi)
 	install_lib_element(L_NS_NSE_NODE, &cfg_no_ns_nse_nsvc_ipa_cmd);
 	install_lib_element(L_NS_NSE_NODE, &cfg_ns_nse_ip_sns_remote_cmd);
 	install_lib_element(L_NS_NSE_NODE, &cfg_no_ns_nse_ip_sns_remote_cmd);
+	install_lib_element(L_NS_NSE_NODE, &cfg_ns_nse_ip_sns_bind_cmd);
+	install_lib_element(L_NS_NSE_NODE, &cfg_no_ns_nse_ip_sns_bind_cmd);
 
 	return 0;
 }
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index 699ed1be..588fabfb 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -185,7 +185,9 @@ gprs_ns2_prim_strs;
 gprs_ns2_recv_prim;
 gprs_ns2_reset_persistent_nsvcs;
 gprs_ns2_start_alive_all_nsvcs;
+gprs_ns2_sns_add_bind;
 gprs_ns2_sns_add_endpoint;
+gprs_ns2_sns_del_bind;
 gprs_ns2_sns_del_endpoint;
 gprs_ns2_vty_init;
 gprs_ns2_vty_init_reduced;
diff --git a/tests/gb/osmo-ns-dummy.cfg b/tests/gb/osmo-ns-dummy.cfg
index 1e6dc76e..72696189 100644
--- a/tests/gb/osmo-ns-dummy.cfg
+++ b/tests/gb/osmo-ns-dummy.cfg
@@ -21,4 +21,5 @@ ns
  nse 1235
   nsvc udp local 127.0.0.3 23000
  nse 1234
+  ip-sns-bind local
   ip-sns-remote 127.0.0.2 2158