gprs_ranap: release Iu UE Context when exiting PMM Connected

PMM Connected defines a Iu signaling connection. The 2 other
PMM states do not have an active Iu signaling connection.

Change-Id: Ie05d2bdf8dfb593b4c7e837107a3a06f22e90119

include/osmocom/sgsn/gprs_ranap.h

@@ -12,8 +12,19 @@ void activate_pdp_rabs(struct sgsn_mm_ctx *ctx);
 int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type type, void *data);
 int iu_rab_act_ps(uint8_t rab_id, struct sgsn_pdp_ctx *pdp);
 
+/* free the Iu UE context */
+void sgsn_ranap_iu_free(struct sgsn_mm_ctx *ctx);
+
+/* send a Iu Release Command and free afterwards the UE context */
+void sgsn_ranap_iu_release_free(struct sgsn_mm_ctx *ctx,
+				const struct RANAP_Cause *cause);
+
 int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id, uint16_t *sai);
-#endif
+
+#else /* ifndef BUILD_IU */
+inline static void sgsn_ranap_iu_free(void *ctx) {};
+inline static void sgsn_ranap_iu_release_free(void *ctx, void *cause) {};
+#endif /* BUILD_IU*/
 
 struct ranap_ue_conn_ctx;
 /* On RANAP, Returns pointer to he associated ranap_ue_conn_ctx in msg, filled

src/sgsn/gprs_mm_state_iu_fsm.c

@@ -6,6 +6,7 @@
 
 #include <osmocom/sgsn/debug.h>
 #include <osmocom/sgsn/sgsn.h>
+#include <osmocom/sgsn/gprs_ranap.h>
 
 #define X(s) (1 << (s))
 
@@ -45,11 +46,15 @@ static void st_pmm_detached(struct osmo_fsm_inst *fi, uint32_t event, void *data
 
 static void st_pmm_connected(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
+	struct sgsn_mm_ctx *ctx = fi->priv;
+
 	switch(event) {
 	case E_PMM_PS_CONN_RELEASE:
+		sgsn_ranap_iu_free(ctx);
 		mm_state_iu_fsm_state_chg(fi, ST_PMM_IDLE);
 		break;
 	case E_PMM_IMPLICIT_DETACH:
+		sgsn_ranap_iu_release_free(ctx, NULL);
 		mm_state_iu_fsm_state_chg(fi, ST_PMM_DETACHED);
 		break;
 	case E_PMM_RA_UPDATE:

src/sgsn/gprs_ranap.c

@@ -119,6 +119,7 @@ int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type
 	mm = sgsn_mm_ctx_by_ue_ctx(ctx);
 	if (!mm) {
 		LOGIUP(ctx, LOGL_NOTICE, "Cannot find mm ctx for IU event %d\n", type);
+		ranap_iu_free_ue(ctx);
 		return rc;
 	}
 
@@ -131,7 +132,11 @@ int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type
 	case RANAP_IU_EVENT_LINK_INVALIDATED:
 		/* Clean up ranap_ue_conn_ctx here */
 		LOGMMCTXP(LOGL_INFO, mm, "IU release for imsi %s\n", mm->imsi);
-		osmo_fsm_inst_dispatch(mm->iu.mm_state_fsm, E_PMM_PS_CONN_RELEASE, NULL);
+		if (mm->iu.mm_state_fsm->state == ST_PMM_CONNECTED)
+			osmo_fsm_inst_dispatch(mm->iu.mm_state_fsm, E_PMM_PS_CONN_RELEASE, NULL);
+		else
+			sgsn_ranap_iu_free(mm);
+
 		rc = 0;
 		break;
 	case RANAP_IU_EVENT_SECURITY_MODE_COMPLETE:
@@ -153,6 +158,35 @@ int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type
 	return rc;
 }
 
+/* TODO: use timers */
+#define TIMEOUT_RANAP_RELEASE_SEC 5
+void sgsn_ranap_iu_free(struct sgsn_mm_ctx *ctx)
+{
+	if (!ctx)
+		return;
+
+	if (!ctx->iu.ue_ctx)
+		return;
+
+	ranap_iu_free_ue(ctx->iu.ue_ctx);
+	ctx->iu.ue_ctx = NULL;
+}
+
+void sgsn_ranap_iu_release_free(struct sgsn_mm_ctx *ctx,
+				const struct RANAP_Cause *cause)
+{
+	if (!ctx)
+		return;
+
+	if (!ctx->iu.ue_ctx)
+		return;
+
+	ranap_iu_tx_release_free(ctx->iu.ue_ctx,
+				 cause,
+				 TIMEOUT_RANAP_RELEASE_SEC);
+	ctx->iu.ue_ctx = NULL;
+}
+
 int iu_rab_act_ps(uint8_t rab_id, struct sgsn_pdp_ctx *pdp)
 {
 	struct msgb *msg;