iuup: Fix Handling of subsequent Initialization msgs

Once the IuUP FSM moved away from Init state, it stopped handling
Initialization messages received from peers and simply ignored them
starting from that point. As a result, if the first IuUP Init ACK it
sent to the peer was lost, the peer would keep retrying with more IuUP
Init and getting no answer.
In any case, it seems possible and desirable that a peer may send an
IuUP Init at a later point, as pointed out vaguely in 3GPP TS 25.415.

sec 6.5.2.1:
"""
Upon reception of a frame indicating that an Initialisation procedure is
active in the peer Iu UP entity, the Iu UP protocol layer forwards the whole
protocol information contained in the INITIALISATION control frame to the
upper layers. It also stores the RAB sub-Flow Combination set (and thus
replaces a possible previous set) in order to control during the transfer of
user data, that the Iu UP payload is correctly formatted (e.g. RFCI matches
the expected Iu UP frame payload total length). The peer Iu UP entity
receiving the INITIALISATION control frame shall choose a version that it
supports among the proposed versions indicated by the sender for which it
has enough initialisation information.
"""

sec B.2.2 "Initialisation State":
"""
After sending a positive acknowledgement of the last INITIALISATION control
frame, the Iu UP instance enters SMpSDU data transfer ready state. Note that
CN does not know if the initialisation ACK was correctly received by the RNC
(and Initialisation procedure successfully completed) until it receives RAB
assignment response, or use data from the RNC. The CN must therefore be able
to continue receiving INITIALISATION control frames by re-entering the
Initialisation state (from Support Mode Data Transfer Ready State), if the CN
has started to send user data before receiving the indication that
Initialisation was successfully completed
"""

sec B.2.3 "Support Mode Data Transfer Ready State":
"""
In case of handover or relocation, Initialisation procedures may have to be
performed and Iu UP instance may have to enter the initialisation state.
"""

Related: SYS#5995
Change-Id: I5cb740702805693cc7f0a550e2e093f9bfdd507c

3 files changed, 19 insertions, 13 deletions

diff --git a/src/gsm/iuup.c b/src/gsm/iuup.c
index 4c0a9482..ca7eb2b8 100644
--- a/src/gsm/iuup.c
+++ b/src/gsm/iuup.c
@@ -734,6 +734,7 @@ static void iuup_fsm_init(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 	}
 }
 
+/* 3GPP TS 25.415 B.2.3 "Support Mode Data Transfer Ready State" */
 static void iuup_fsm_smpsdu_data(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct osmo_iuup_instance *iui = fi->priv;
@@ -745,6 +746,14 @@ static void iuup_fsm_smpsdu_data(struct osmo_fsm_inst *fi, uint32_t event, void
 		irp = data;
 		osmo_fsm_inst_state_chg(fi, IUUP_FSM_ST_NULL, 0, 0);
 		break;
+	case IUUP_FSM_EVT_INIT:
+		/* "In case of handover or relocation, Initialisation procedures
+		 * may have to be performed and Iu UP instance may have to enter
+		 * the initialisation state." */
+		itp = data;
+		if (!iuup_rx_initialization(iui, itp))
+			osmo_fsm_inst_state_chg(fi, IUUP_FSM_ST_INIT, 0, 0);
+		break;
 	case IUUP_FSM_EVT_IUUP_DATA_REQ:
 		/* Data coming down from RNL (user) towards TNL (transport) */
 		irp = data;
@@ -821,6 +830,7 @@ static const struct osmo_fsm_state iuup_fsm_states[] = {
 	},
 	[IUUP_FSM_ST_SMpSDU_DATA_XFER_READY] = {
 		.in_event_mask = S(IUUP_FSM_EVT_IUUP_CONFIG_REQ) |
+				 S(IUUP_FSM_EVT_INIT) |
 				 S(IUUP_FSM_EVT_IUUP_DATA_REQ) |
 				 S(IUUP_FSM_EVT_IUUP_DATA_IND),
 		.out_state_mask = S(IUUP_FSM_ST_NULL) |
diff --git a/tests/iuup/iuup_test.c b/tests/iuup/iuup_test.c
index 5b553509..e40b9e77 100644
--- a/tests/iuup/iuup_test.c
+++ b/tests/iuup/iuup_test.c
@@ -541,12 +541,10 @@ static int _passive_init_retrans_user_prim_cb(struct osmo_prim_hdr *oph, void *c
 
 	switch (_passive_init_retrans_user_rx_prim) {
 	case 0:
-	/* FIXME expected case: case 1: */
+	case 1:
 		OSMO_ASSERT(OSMO_PRIM_HDR(&irp->oph) == OSMO_PRIM(OSMO_IUUP_RNL_STATUS, PRIM_OP_INDICATION));
 		OSMO_ASSERT(irp->u.status.procedure == IUUP_PROC_INIT);
 		break;
-	/* FIXME current case: */
-	case 1:
 	case 2:
 	default:
 		OSMO_ASSERT(OSMO_PRIM_HDR(&irp->oph) == OSMO_PRIM(OSMO_IUUP_RNL_DATA, PRIM_OP_INDICATION));
@@ -603,14 +601,9 @@ void test_passive_init_retrans(void)
 	tnp->oph.msg->l2h = msgb_put(tnp->oph.msg, sizeof(iuup_initialization));
 	hdr14 = (struct iuup_pdutype14_hdr *)msgb_l2(tnp->oph.msg);
 	memcpy(hdr14, iuup_initialization, sizeof(iuup_initialization));
-	/* FIXME: unexpected result, should be fixed: */
-	OSMO_ASSERT((rc = osmo_iuup_tnl_prim_up(iui, tnp)) < 0); /* INIT not perrmited */
-	OSMO_ASSERT(_passive_init_transport_rx_prim == 1); /* We receive an Init ACK */
-	OSMO_ASSERT(_passive_init_retrans_user_rx_prim == 1); /* We receive the Status-Init.ind */
-	/* FIXME: expected result: */
-	//OSMO_ASSERT((rc = osmo_iuup_tnl_prim_up(iui, tnp)) == 0);
-	//OSMO_ASSERT(_passive_init_transport_rx_prim == 2); /* We receive another Init ACK */
-	//OSMO_ASSERT(_passive_init_retrans_user_rx_prim == 2); /* We receive another Status-Init.ind */
+	OSMO_ASSERT((rc = osmo_iuup_tnl_prim_up(iui, tnp)) == 0);
+	OSMO_ASSERT(_passive_init_transport_rx_prim == 2); /* We receive another Init ACK */
+	OSMO_ASSERT(_passive_init_retrans_user_rx_prim == 2); /* We receive another Status-Init.ind */
 
 	/* Send IuUP incoming data to the implementation: */
 	tnp = osmo_iuup_tnl_prim_alloc(iuup_test_ctx, OSMO_IUUP_TNL_UNITDATA, PRIM_OP_INDICATION, IUUP_MSGB_SIZE);
@@ -619,7 +612,7 @@ void test_passive_init_retrans(void)
 	memcpy(hdr0, iuup_data, sizeof(iuup_data));
 	OSMO_ASSERT((rc = osmo_iuup_tnl_prim_up(iui, tnp)) == 0);
 	/* We receive it in RNL: */
-	OSMO_ASSERT(_passive_init_retrans_user_rx_prim == 2);
+	OSMO_ASSERT(_passive_init_retrans_user_rx_prim == 3);
 
 	/* Now in opposite direction, RNL->[IuuP]->TNL: */
 	rnp = osmo_iuup_rnl_prim_alloc(iuup_test_ctx, OSMO_IUUP_RNL_DATA, PRIM_OP_REQUEST, IUUP_MSGB_SIZE);
@@ -629,7 +622,7 @@ void test_passive_init_retrans(void)
 	rnp->oph.msg->l3h = msgb_put(rnp->oph.msg, sizeof(iuup_data) - 4);
 	memcpy(rnp->oph.msg->l3h, iuup_data + 4, sizeof(iuup_data) - 4);
 	OSMO_ASSERT((rc = osmo_iuup_rnl_prim_down(iui, rnp)) == 0);
-	OSMO_ASSERT(_passive_init_transport_rx_prim == 2); /* We receive data in TNL */
+	OSMO_ASSERT(_passive_init_transport_rx_prim == 3); /* We receive data in TNL */
 
 	osmo_iuup_instance_free(iui);
 }
diff --git a/tests/iuup/iuup_test.ok b/tests/iuup/iuup_test.ok
index 93f69547..57baba9c 100644
--- a/tests/iuup/iuup_test.ok
+++ b/tests/iuup/iuup_test.ok
@@ -48,6 +48,9 @@ _passive_init_retrans_user_prim_cb()
 _passive_init_transport_prim_cb()
 Transport: DL len=4: e4 00 24 00 
 _passive_init_retrans_user_prim_cb()
+_passive_init_transport_prim_cb()
+Transport: DL len=4: e4 00 24 00 
+_passive_init_retrans_user_prim_cb()
 User: UL len=31: 08 55 6d 94 4c 71 a1 a0 81 e7 ea d2 04 24 44 80 00 0e cd 82 b8 11 18 00 00 97 c4 79 4e 77 40 
 _passive_init_transport_prim_cb()
 Transport: DL len=35: 01 00 e3 ff 08 55 6d 94 4c 71 a1 a0 81 e7 ea d2 04 24 44 80 00 0e cd 82 b8 11 18 00 00 97 c4 79 4e 77 40