ipa: Use ASP name as ipa_unit_name on dynamic ASPs

A recent patch fixed a long problem where the ASP name (instead of
expected AS name) was used as ipa_unit_name in IPA based ASPs.
For server side it doesn't matter much, sense anyway the ipa_unit_name
is actually restored on the struct with what's received in IPA GET_RESP
message (see ipa_asp_fsm_wait_id_resp()). So the fix was actually for
the client side in the scenario where a non-dynamic ASP with an assigned
AS was configured in the VTY.

However, dynamic ASPs usually have no assigned AS (because in general it
is really not created/configured, as the ASP is created on the flight).
As a result, the recent patch (see "Fixes" below), broke dynamic ASPs
case because from then one ipa_asp_fsm_start() would fail and terminate
the FSM because ipa_find_as_for_asp() was returning NULL.

So improve the recent patch by applying the previous logic for dynamic
ASPs:
* On the server side, it really doesn't matter since as mentioned, the
  field will be repopulated later on, but allows the code to avoid
  terminating the FSM and hence be brought up and be ready to receive
  clients.
* On the client case, this is how dynamic IPA ASPs were ment to be used
  when they were introduced anyway (use ASP as ipa_unit_id, meaning
  "AS name" == "ASP name").

Furthermore, on the client side, the non-dynamic IPA ASPs need their
bring up be delayed until assigned to an AS, because the AS name is sent
in ipa_unit_name field in Tx IPA ID RESP.
This usually happens at a later point than ASP (FSM) creation, because
first the ASP object is created (through VTY or API) and then assigned
to an AS through osmo_ss7_as_add_asp() usually from a later "asp" vty
command in the "as" node.

Fixes: 65741dca05
Change-Id: I0a741449450c998253b1e44a76a3b7fc224e0903
Related: SYS#5914

src/osmo_ss7_as.c

@@ -35,6 +35,7 @@
 
 #include "ss7_internal.h"
 #include "xua_as_fsm.h"
+#include "xua_asp_fsm.h"
 
 /***********************************************************************
  * SS7 Application Server
@@ -114,6 +115,7 @@ int osmo_ss7_as_add_asp(struct osmo_ss7_as *as, const char *asp_name)
 	for (i = 0; i < ARRAY_SIZE(as->cfg.asps); i++) {
 		if (!as->cfg.asps[i]) {
 			as->cfg.asps[i] = asp;
+			osmo_fsm_inst_dispatch(asp->fi, XUA_ASP_E_AS_ASSIGNED, as);
 			return 0;
 		}
 	}

src/xua_asp_fsm.c

@@ -65,6 +65,8 @@ static const struct value_string xua_asp_event_names[] = {
 	{ XUA_ASP_E_ASPSM_BEAT,		"ASPSM_BEAT" },
 	{ XUA_ASP_E_ASPSM_BEAT_ACK,	"ASPSM_BEAT_ACK" },
 
+	{ XUA_ASP_E_AS_ASSIGNED,	"AS_ASSIGNED" },
+
 	{ IPA_ASP_E_ID_RESP,		"IPA_CCM_ID_RESP" },
 	{ IPA_ASP_E_ID_GET,		"IPA_CCM_ID_GET" },
 	{ IPA_ASP_E_ID_ACK,		"IPA_CCM_ID_ACK" },
@@ -687,6 +689,9 @@ static void xua_asp_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *dat
 	case XUA_ASP_E_ASPSM_BEAT_ACK:
 		/* FIXME: stop timer, if any */
 		break;
+	case XUA_ASP_E_AS_ASSIGNED:
+		/* Ignore, only used in IPA asps so far. */
+		break;
 	default:
 		break;
 	}
@@ -1058,6 +1063,7 @@ static void ipa_asp_fsm_inactive(struct osmo_fsm_inst *fi, uint32_t event, void
 static void ipa_asp_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct ipa_asp_fsm_priv *iafp = fi->priv;
+	struct osmo_ss7_as *as;
 	int fd;
 
 	switch (event) {
@@ -1077,6 +1083,15 @@ static void ipa_asp_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *dat
 		/* stop timer, if any */
 		osmo_timer_del(&iafp->pong_timer);
 		break;
+	case XUA_ASP_E_AS_ASSIGNED:
+		as = data;
+		osmo_talloc_replace_string(iafp->ipa_unit, &iafp->ipa_unit->unit_name, as->cfg.name);
+		/* Now that the AS is known, start the client side: */
+		if (iafp->role == OSMO_SS7_ASP_ROLE_ASP && fi->state == IPA_ASP_S_DOWN) {
+			LOGPFSML(fi, LOGL_NOTICE, "Bringing up ASP now once it has been assigned to an AS\n");
+			osmo_fsm_inst_dispatch(fi, XUA_ASP_E_M_ASP_UP_REQ, NULL);
+		}
+		break;
 	default:
 		break;
 	}
@@ -1175,7 +1190,8 @@ struct osmo_fsm ipa_asp_fsm = {
 	.allstate_event_mask = S(XUA_ASP_E_SCTP_COMM_DOWN_IND) |
 			       S(XUA_ASP_E_SCTP_RESTART_IND) |
 			       S(XUA_ASP_E_ASPSM_BEAT) |
-			       S(XUA_ASP_E_ASPSM_BEAT_ACK),
+			       S(XUA_ASP_E_ASPSM_BEAT_ACK) |
+			       S(XUA_ASP_E_AS_ASSIGNED),
 	.allstate_action = ipa_asp_allstate,
 };
 
@@ -1191,30 +1207,44 @@ static struct osmo_fsm_inst *ipa_asp_fsm_start(struct osmo_ss7_asp *asp,
 	struct osmo_fsm_inst *fi;
 	struct ipa_asp_fsm_priv *iafp;
 	struct osmo_ss7_as *as = ipa_find_as_for_asp(asp);
+	const char *unit_name;
+	bool can_start = true;
 
 	/* allocate as child of AS? */
 	fi = osmo_fsm_inst_alloc(&ipa_asp_fsm, asp, NULL, log_level, asp->cfg.name);
 
-	if (!as) {
-		osmo_fsm_inst_term(fi, OSMO_FSM_TERM_ERROR, NULL);
-		return NULL;
-	}
-
 	iafp = talloc_zero(fi, struct ipa_asp_fsm_priv);
 	if (!iafp) {
 		osmo_fsm_inst_term(fi, OSMO_FSM_TERM_ERROR, NULL);
 		return NULL;
 	}
+
+	if (as) {
+		unit_name = as->cfg.name;
+	} else if (asp->dyn_allocated) {
+		LOGPFSML(fi, LOGL_INFO, "Dynamic ASP is not assigned to any AS, "
+			 "using ASP name instead of AS name as ipa_unit_name\n");
+		unit_name = asp->cfg.name;
+	} else {
+		/* ASP in client mode will be brought up when this ASP is added
+		 * to an AS, see XUA_ASP_E_AS_ASSIGNED. */
+		if (role == OSMO_SS7_ASP_ROLE_ASP) {
+			LOGPFSML(fi, LOGL_NOTICE, "ASP is not assigned to any AS. ASP bring up delayed\n");
+			can_start = false;
+		}
+		unit_name = asp->cfg.name;
+	}
+
 	iafp->role = role;
 	iafp->asp = asp;
 	iafp->ipa_unit = talloc_zero(iafp, struct ipaccess_unit);
-	iafp->ipa_unit->unit_name = talloc_strdup(iafp->ipa_unit, as->cfg.name);
+	iafp->ipa_unit->unit_name = talloc_strdup(iafp->ipa_unit, unit_name);
 	iafp->pong_timer.cb = ipa_pong_timer_cb;
 	iafp->pong_timer.data = fi;
 
 	fi->priv = iafp;
 
-	if (role == OSMO_SS7_ASP_ROLE_ASP)
+	if (can_start && role == OSMO_SS7_ASP_ROLE_ASP)
 		osmo_fsm_inst_dispatch(fi, XUA_ASP_E_M_ASP_UP_REQ, NULL);
 
 	return fi;

src/xua_asp_fsm.h

@@ -28,6 +28,9 @@ enum xua_asp_event {
 	XUA_ASP_E_ASPSM_BEAT,
 	XUA_ASP_E_ASPSM_BEAT_ACK,
 
+	/* The ASP was added to an AS. data: (struct osmo_ss7_as *) */
+	XUA_ASP_E_AS_ASSIGNED,
+
 	/* IPA specific */
 	IPA_ASP_E_ID_RESP,
 	IPA_ASP_E_ID_ACK,