Move lots of Iu/ranap specific code into its own file

RANAP related functionalities were splitted among several files
(gprs_gmm.c, gprs_sgsn.c and sgsn_libgtp.c). Let's move it into its own
file to shrink complexity/size of existing files.
It also allows to keep a lot of conditionally enabled code (BUILD_IU)
and its dependencies (osmo-iuh) together.

Change-Id: I549042aaff045a378de77d657cc396ee08f22f33

11 files changed, 274 insertions, 238 deletions

diff --git a/include/osmocom/sgsn/Makefile.am b/include/osmocom/sgsn/Makefile.am
index cbf7c51b6..b4cd5db06 100644
--- a/include/osmocom/sgsn/Makefile.am
+++ b/include/osmocom/sgsn/Makefile.am
@@ -8,6 +8,7 @@ noinst_HEADERS = \
 	gprs_gmm_attach.h \
 	gprs_llc.h \
 	gprs_llc_xid.h \
+	gprs_ranap.h \
 	gprs_sgsn.h \
 	gprs_sndcp_comp.h \
 	gprs_sndcp_dcomp.h \
diff --git a/include/osmocom/sgsn/gprs_gmm.h b/include/osmocom/sgsn/gprs_gmm.h
index ffcebd353..047bd7748 100644
--- a/include/osmocom/sgsn/gprs_gmm.h
+++ b/include/osmocom/sgsn/gprs_gmm.h
@@ -17,8 +17,10 @@ int gsm48_tx_gmm_auth_ciph_req(struct sgsn_mm_ctx *mm,
 
 int gsm0408_gprs_rcvmsg_gb(struct msgb *msg, struct gprs_llc_llme *llme,
 			   bool drop_cipherable);
-int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id,
-			   uint16_t *sai);
+int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
+			   struct gprs_llc_llme *llme);
+int gsm0408_rcv_gmm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
+			   struct gprs_llc_llme *llme, bool drop_cipherable);
 int gsm0408_gprs_force_reattach(struct sgsn_mm_ctx *mmctx);
 int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg,
 				       struct gprs_llc_llme *llme);
@@ -33,8 +35,6 @@ int gprs_gmm_rx_resume(struct gprs_ra_id *raid, uint32_t tlli,
 
 time_t gprs_max_time_to_idle(void);
 
-int iu_rab_act_ps(uint8_t rab_id, struct sgsn_pdp_ctx *pdp);
-
 int gsm48_tx_gmm_id_req(struct sgsn_mm_ctx *mm, uint8_t id_type);
 int gsm48_tx_gmm_att_rej(struct sgsn_mm_ctx *mm,
 				uint8_t gmm_cause);
@@ -42,9 +42,12 @@ int gsm48_tx_gmm_att_ack(struct sgsn_mm_ctx *mm);
 
 int gprs_gmm_attach_req_ies(struct msgb *a, struct msgb *b);
 
+int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx);
 /* TODO: move extract_subscr_* when gsm48_gmm_authorize() got removed */
 void extract_subscr_msisdn(struct sgsn_mm_ctx *ctx);
 void extract_subscr_hlr(struct sgsn_mm_ctx *ctx);
 
 void pdp_ctx_detach_mm_ctx(struct sgsn_pdp_ctx *pdp);
+
+void mmctx_set_pmm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state state);
 #endif /* _GPRS_GMM_H */
diff --git a/include/osmocom/sgsn/gprs_ranap.h b/include/osmocom/sgsn/gprs_ranap.h
new file mode 100644
index 000000000..b300130ac
--- /dev/null
+++ b/include/osmocom/sgsn/gprs_ranap.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/sgsn/gprs_sgsn.h>
+
+#ifdef BUILD_IU
+#include <osmocom/ranap/ranap_ies_defs.h>
+#include <osmocom/ranap/ranap_msg_factory.h>
+#include <osmocom/ranap/iu_client.h>
+
+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);
+
+int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id, uint16_t *sai);
+#endif
+
+struct ranap_ue_conn_ctx;
+/* On RANAP, Returns pointer to he associated ranap_ue_conn_ctx in msg, filled
+ * in by osmo-iuh's iu_recv_cb().
+ * On Gb, returns NULL */
+#define MSG_IU_UE_CTX(msg) ((struct ranap_ue_conn_ctx *)(msg)->dst)
+#define MSG_IU_UE_CTX_SET(msg, val) (msg)->dst = (val)
diff --git a/include/osmocom/sgsn/sgsn.h b/include/osmocom/sgsn/sgsn.h
index 78803c77b..e1c5c4aff 100644
--- a/include/osmocom/sgsn/sgsn.h
+++ b/include/osmocom/sgsn/sgsn.h
@@ -161,7 +161,7 @@ char *sgsn_gtp_ntoa(struct ul16_t *ul);
 /* Main input function for Gb proxy */
 int sgsn_rcvmsg(struct msgb *msg, struct gprs_nsvc *nsvc, uint16_t ns_bvci);
 
-
+/* sgsn_libgtp.c */
 struct sgsn_pdp_ctx *sgsn_create_pdp_ctx(struct sgsn_ggsn_ctx *ggsn,
 					 struct sgsn_mm_ctx *mmctx,
 					 uint16_t nsapi,
@@ -169,6 +169,7 @@ struct sgsn_pdp_ctx *sgsn_create_pdp_ctx(struct sgsn_ggsn_ctx *ggsn,
 int sgsn_delete_pdp_ctx(struct sgsn_pdp_ctx *pctx);
 void sgsn_pdp_upd_gtp_u(struct sgsn_pdp_ctx *pdp, void *addr, size_t alen);
 void sgsn_ggsn_echo_req(struct sgsn_ggsn_ctx *ggc);
+int send_act_pdp_cont_acc(struct sgsn_pdp_ctx *pctx);
 
 /* gprs_sndcp.c */
 
diff --git a/src/gprs/Makefile.am b/src/gprs/Makefile.am
index ba5dfd617..384b893f3 100644
--- a/src/gprs/Makefile.am
+++ b/src/gprs/Makefile.am
@@ -62,6 +62,7 @@ osmo_gbproxy_LDADD = \
 osmo_sgsn_SOURCES = \
 	gprs_gmm_attach.c \
 	gprs_gmm.c \
+	gprs_ranap.c \
 	gprs_sgsn.c \
 	gprs_sndcp.c \
 	gprs_sndcp_comp.c \
diff --git a/src/gprs/gprs_gmm.c b/src/gprs/gprs_gmm.c
index 00335e8a8..5700ee503 100644
--- a/src/gprs/gprs_gmm.c
+++ b/src/gprs/gprs_gmm.c
@@ -47,12 +47,6 @@
 
 #include <osmocom/gprs/gprs_bssgp.h>
 
-#ifdef BUILD_IU
-#include <osmocom/ranap/ranap_ies_defs.h>
-#include <osmocom/ranap/ranap_msg_factory.h>
-#include <osmocom/ranap/iu_client.h>
-#endif
-
 #include <osmocom/sgsn/debug.h>
 #include <osmocom/sgsn/gprs_llc.h>
 #include <osmocom/sgsn/gprs_sgsn.h>
@@ -63,6 +57,7 @@
 #include <osmocom/sgsn/gprs_gmm_attach.h>
 #include <osmocom/sgsn/signal.h>
 #include <osmocom/sgsn/gprs_sndcp.h>
+#include <osmocom/sgsn/gprs_ranap.h>
 
 #include <pdp.h>
 
@@ -117,14 +112,6 @@ static const struct value_string gprs_pmm_state_names[] = {
 	{ 0, NULL }
 };
 
-/* On RANAP, Returns pointer to he associated ranap_ue_conn_ctx in msg, filled
- * in by osmo-iuh's iu_recv_cb().
- * On Gb, returns NULL */
-#define MSG_IU_UE_CTX(msg) ((struct ranap_ue_conn_ctx *)(msg)->dst)
-#define MSG_IU_UE_CTX_SET(msg, val) (msg)->dst = (val)
-
-static int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx);
-
 static void mmctx_change_gtpu_endpoints_to_sgsn(struct sgsn_mm_ctx *mm_ctx)
 {
 	struct sgsn_pdp_ctx *pdp;
@@ -188,7 +175,7 @@ static void mmctx_state_timer_stop(struct sgsn_mm_ctx *mm, unsigned int T)
 	mm->gb.state_T = 0;
 }
 
-static void mmctx_set_pmm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state state)
+void mmctx_set_pmm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state state)
 {
 	OSMO_ASSERT(ctx->ran_type == MM_CTX_T_UTRAN_Iu);
 
@@ -245,62 +232,6 @@ static void mmctx_set_mm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state stat
 	ctx->pmm_state = state;
 }
 
-#ifdef BUILD_IU
-int sgsn_ranap_rab_ass_resp(struct sgsn_mm_ctx *ctx, RANAP_RAB_SetupOrModifiedItemIEs_t *setup_ies);
-int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type type, void *data)
-{
-	struct sgsn_mm_ctx *mm;
-	int rc = -1;
-
-	mm = sgsn_mm_ctx_by_ue_ctx(ctx);
-
-#define REQUIRE_MM \
-	if (!mm) { \
-		LOGIUP(ctx, LOGL_NOTICE, "Cannot find mm ctx for IU event %d\n", type); \
-		return rc; \
-	}
-
-	switch (type) {
-	case RANAP_IU_EVENT_RAB_ASSIGN:
-		REQUIRE_MM
-		rc = sgsn_ranap_rab_ass_resp(mm, (RANAP_RAB_SetupOrModifiedItemIEs_t *)data);
-		break;
-	case RANAP_IU_EVENT_IU_RELEASE:
-		/* fall thru */
-	case RANAP_IU_EVENT_LINK_INVALIDATED:
-		/* Clean up ranap_ue_conn_ctx here */
-		if (mm)
-			LOGMMCTXP(LOGL_INFO, mm, "IU release for imsi %s\n", mm->imsi);
-		else
-			LOGIUP(ctx, LOGL_INFO, "IU release\n");
-		if (mm && mm->pmm_state == PMM_CONNECTED)
-			mmctx_set_pmm_state(mm, PMM_IDLE);
-		rc = 0;
-		break;
-	case RANAP_IU_EVENT_SECURITY_MODE_COMPLETE:
-		REQUIRE_MM
-		/* Continue authentication here */
-		mm->iu.ue_ctx->integrity_active = 1;
-
-		/* FIXME: remove gmm_authorize */
-		if (mm->pending_req != GSM48_MT_GMM_ATTACH_REQ)
-			gsm48_gmm_authorize(mm);
-		else
-			osmo_fsm_inst_dispatch(mm->gmm_att_req.fsm, E_IU_SECURITY_CMD_COMPLETE, NULL);
-		break;
-	default:
-		if (mm)
-			LOGMMCTXP(LOGL_NOTICE, mm, "Unknown event received: %i\n", type);
-		else
-			LOGIUP(ctx, LOGL_NOTICE, "Unknown event received: %i\n", type);
-		rc = -1;
-		break;
-	}
-	return rc;
-}
-#endif
-
-
 /* Our implementation, should be kept in SGSN */
 
 static void mmctx_timer_cb(void *_mm);
@@ -1078,21 +1009,8 @@ static int gsm48_tx_gmm_service_rej(struct sgsn_mm_ctx *mm,
 
 static int gsm48_tx_gmm_ra_upd_ack(struct sgsn_mm_ctx *mm);
 
-#ifdef BUILD_IU
-/* Send RAB activation requests for all PDP contexts */
-void activate_pdp_rabs(struct sgsn_mm_ctx *ctx)
-{
-	struct sgsn_pdp_ctx *pdp;
-	if (ctx->ran_type != MM_CTX_T_UTRAN_Iu)
-		return;
-	llist_for_each_entry(pdp, &ctx->pdp_list, list) {
-		iu_rab_act_ps(pdp->nsapi, pdp);
-	}
-}
-#endif
-
 /* Check if we can already authorize a subscriber */
-static int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx)
+int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx)
 {
 #ifdef BUILD_IU
 	int rc;
@@ -2061,7 +1979,7 @@ static int gsm48_rx_gmm_status(struct sgsn_mm_ctx *mmctx, struct msgb *msg)
 }
 
 /* Rx GPRS Mobility Management. MMCTX can be NULL when called. On !Gb (Iu), llme is NULL  */
-static int gsm0408_rcv_gmm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
+int gsm0408_rcv_gmm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
 			   struct gprs_llc_llme *llme, bool drop_cipherable)
 {
 	struct sgsn_signal_data sig_data;
@@ -2933,7 +2851,7 @@ static void pdpctx_timer_cb(void *_pdp)
 
 
 /* GPRS Session Management */
-static int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
+int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
 			   struct gprs_llc_llme *llme)
 {
 	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
@@ -3008,45 +2926,6 @@ int gsm0408_gprs_force_reattach(struct sgsn_mm_ctx *mmctx)
 	return rc;
 }
 
-/* Main entry point for incoming 04.08 GPRS messages from Iu */
-int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id,
-			   uint16_t *sai)
-{
-	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
-	uint8_t pdisc = gsm48_hdr_pdisc(gh);
-	struct sgsn_mm_ctx *mmctx;
-	int rc = -EINVAL;
-
-	mmctx = sgsn_mm_ctx_by_ue_ctx(MSG_IU_UE_CTX(msg));
-	if (mmctx) {
-		rate_ctr_inc(&mmctx->ctrg->ctr[GMM_CTR_PKTS_SIG_IN]);
-		if (ra_id)
-			memcpy(&mmctx->ra, ra_id, sizeof(mmctx->ra));
-	}
-
-	/* MMCTX can be NULL */
-
-	switch (pdisc) {
-	case GSM48_PDISC_MM_GPRS:
-		rc = gsm0408_rcv_gmm(mmctx, msg, NULL, false);
-#pragma message "set drop_cipherable arg for gsm0408_rcv_gmm() from IuPS?"
-		break;
-	case GSM48_PDISC_SM_GPRS:
-		rc = gsm0408_rcv_gsm(mmctx, msg, NULL);
-		break;
-	default:
-		LOGMMCTXP(LOGL_NOTICE, mmctx,
-			"Unknown GSM 04.08 discriminator 0x%02x: %s\n",
-			pdisc, osmo_hexdump((uint8_t *)gh, msgb_l3len(msg)));
-		/* FIXME: return status message */
-		break;
-	}
-
-	/* MMCTX can be invalid */
-
-	return rc;
-}
-
 /* Update the MM context state */
 static void gsm0408_gprs_notify_pdu_gb(struct sgsn_mm_ctx *mmctx)
 {
@@ -3154,30 +3033,3 @@ int gprs_gmm_rx_resume(struct gprs_ra_id *raid, uint32_t tlli,
 	mmctx->gmm_state = GMM_REGISTERED_NORMAL;
 	return 0;
 }
-
-#ifdef BUILD_IU
-int iu_rab_act_ps(uint8_t rab_id, struct sgsn_pdp_ctx *pdp)
-{
-	struct msgb *msg;
-	struct sgsn_mm_ctx *mm = pdp->mm;
-	struct ranap_ue_conn_ctx *uectx;
-	uint32_t ggsn_ip;
-	bool use_x213_nsap;
-
-	uectx = mm->iu.ue_ctx;
-	use_x213_nsap = (uectx->rab_assign_addr_enc == RANAP_NSAP_ADDR_ENC_X213);
-
-	/* Get the IP address for ggsn user plane */
-	memcpy(&ggsn_ip, pdp->lib->gsnru.v, pdp->lib->gsnru.l);
-	ggsn_ip = htonl(ggsn_ip);
-
-	LOGP(DRANAP, LOGL_DEBUG, "Assigning RAB: rab_id=%d, ggsn_ip=%x,"
-	     " teid_gn=%x, use_x213_nsap=%d\n",
-	     rab_id, ggsn_ip, pdp->lib->teid_gn, use_x213_nsap);
-
-	msg = ranap_new_msg_rab_assign_data(rab_id, ggsn_ip,
-					    pdp->lib->teid_gn, use_x213_nsap);
-	msg->l2h = msg->data;
-	return ranap_iu_rab_act(uectx, msg);
-}
-#endif
diff --git a/src/gprs/gprs_ranap.c b/src/gprs/gprs_ranap.c
new file mode 100644
index 000000000..e0470f609
--- /dev/null
+++ b/src/gprs/gprs_ranap.c
@@ -0,0 +1,231 @@
+/* Messages on the RANAP interface (Iu mode) */
+
+/* (C) 2009-2015 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2015 by Holger Hans Peter Freyther
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "bscconfig.h"
+
+#ifdef BUILD_IU
+
+#include <gtp.h>
+
+#include <osmocom/core/rate_ctr.h>
+
+#include <osmocom/ranap/ranap_common.h>
+
+#include <osmocom/sgsn/gprs_gmm.h>
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/sgsn.h>
+#include <osmocom/sgsn/gprs_ranap.h>
+#include <osmocom/sgsn/gprs_gmm_attach.h>
+
+/* Send RAB activation requests for all PDP contexts */
+void activate_pdp_rabs(struct sgsn_mm_ctx *ctx)
+{
+	struct sgsn_pdp_ctx *pdp;
+	if (ctx->ran_type != MM_CTX_T_UTRAN_Iu)
+		return;
+	llist_for_each_entry(pdp, &ctx->pdp_list, list) {
+		iu_rab_act_ps(pdp->nsapi, pdp);
+	}
+}
+
+/* Callback for RAB assignment response */
+static int sgsn_ranap_rab_ass_resp(struct sgsn_mm_ctx *ctx, RANAP_RAB_SetupOrModifiedItemIEs_t *setup_ies)
+{
+	uint8_t rab_id;
+	bool require_pdp_update = false;
+	struct sgsn_pdp_ctx *pdp = NULL;
+	RANAP_RAB_SetupOrModifiedItem_t *item = &setup_ies->raB_SetupOrModifiedItem;
+
+	rab_id = item->rAB_ID.buf[0];
+
+	pdp = sgsn_pdp_ctx_by_nsapi(ctx, rab_id);
+	if (!pdp) {
+		LOGP(DRANAP, LOGL_ERROR, "RAB Assignment Response for unknown RAB/NSAPI=%u\n", rab_id);
+		return -1;
+	}
+
+	if (item->transportLayerAddress) {
+		LOGPC(DRANAP, LOGL_INFO, " Setup: (%u/%s)", rab_id, osmo_hexdump(item->transportLayerAddress->buf,
+								     item->transportLayerAddress->size));
+		switch (item->transportLayerAddress->size) {
+		case 7:
+			/* It must be IPv4 inside a X213 NSAP */
+			memcpy(pdp->lib->gsnlu.v, &item->transportLayerAddress->buf[3], 4);
+			break;
+		case 4:
+			/* It must be a raw IPv4 address */
+			memcpy(pdp->lib->gsnlu.v, item->transportLayerAddress->buf, 4);
+			break;
+		case 16:
+			/* TODO: It must be a raw IPv6 address */
+		case 19:
+			/* TODO: It must be IPv6 inside a X213 NSAP */
+		default:
+			LOGP(DRANAP, LOGL_ERROR, "RAB Assignment Resp: Unknown "
+				"transport layer address size %u\n",
+				item->transportLayerAddress->size);
+			return -1;
+		}
+		require_pdp_update = true;
+	}
+
+	/* The TEI on the RNC side might have changed, too */
+	if (item->iuTransportAssociation &&
+	    item->iuTransportAssociation->present == RANAP_IuTransportAssociation_PR_gTP_TEI &&
+	    item->iuTransportAssociation->choice.gTP_TEI.buf &&
+	    item->iuTransportAssociation->choice.gTP_TEI.size >= 4) {
+		uint32_t tei = osmo_load32be(item->iuTransportAssociation->choice.gTP_TEI.buf);
+		LOGP(DRANAP, LOGL_DEBUG, "Updating TEID on RNC side from 0x%08x to 0x%08x\n",
+			pdp->lib->teid_own, tei);
+		pdp->lib->teid_own = tei;
+		require_pdp_update = true;
+	}
+
+	if (require_pdp_update)
+		gtp_update_context(pdp->ggsn->gsn, pdp->lib, pdp, &pdp->lib->hisaddr0);
+
+	if (pdp->state != PDP_STATE_CR_CONF) {
+		send_act_pdp_cont_acc(pdp);
+		pdp->state = PDP_STATE_CR_CONF;
+	}
+	return 0;
+
+}
+
+int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type type, void *data)
+{
+	struct sgsn_mm_ctx *mm;
+	int rc = -1;
+
+	mm = sgsn_mm_ctx_by_ue_ctx(ctx);
+
+#define REQUIRE_MM \
+	if (!mm) { \
+		LOGIUP(ctx, LOGL_NOTICE, "Cannot find mm ctx for IU event %d\n", type); \
+		return rc; \
+	}
+
+	switch (type) {
+	case RANAP_IU_EVENT_RAB_ASSIGN:
+		REQUIRE_MM
+		rc = sgsn_ranap_rab_ass_resp(mm, (RANAP_RAB_SetupOrModifiedItemIEs_t *)data);
+		break;
+	case RANAP_IU_EVENT_IU_RELEASE:
+		/* fall thru */
+	case RANAP_IU_EVENT_LINK_INVALIDATED:
+		/* Clean up ranap_ue_conn_ctx here */
+		if (mm)
+			LOGMMCTXP(LOGL_INFO, mm, "IU release for imsi %s\n", mm->imsi);
+		else
+			LOGIUP(ctx, LOGL_INFO, "IU release\n");
+		if (mm && mm->pmm_state == PMM_CONNECTED)
+			mmctx_set_pmm_state(mm, PMM_IDLE);
+		rc = 0;
+		break;
+	case RANAP_IU_EVENT_SECURITY_MODE_COMPLETE:
+		REQUIRE_MM
+		/* Continue authentication here */
+		mm->iu.ue_ctx->integrity_active = 1;
+
+		/* FIXME: remove gmm_authorize */
+		if (mm->pending_req != GSM48_MT_GMM_ATTACH_REQ)
+			gsm48_gmm_authorize(mm);
+		else
+			osmo_fsm_inst_dispatch(mm->gmm_att_req.fsm, E_IU_SECURITY_CMD_COMPLETE, NULL);
+		break;
+	default:
+		if (mm)
+			LOGMMCTXP(LOGL_NOTICE, mm, "Unknown event received: %i\n", type);
+		else
+			LOGIUP(ctx, LOGL_NOTICE, "Unknown event received: %i\n", type);
+		rc = -1;
+		break;
+	}
+	return rc;
+}
+
+int iu_rab_act_ps(uint8_t rab_id, struct sgsn_pdp_ctx *pdp)
+{
+	struct msgb *msg;
+	struct sgsn_mm_ctx *mm = pdp->mm;
+	struct ranap_ue_conn_ctx *uectx;
+	uint32_t ggsn_ip;
+	bool use_x213_nsap;
+
+	uectx = mm->iu.ue_ctx;
+	use_x213_nsap = (uectx->rab_assign_addr_enc == RANAP_NSAP_ADDR_ENC_X213);
+
+	/* Get the IP address for ggsn user plane */
+	memcpy(&ggsn_ip, pdp->lib->gsnru.v, pdp->lib->gsnru.l);
+	ggsn_ip = htonl(ggsn_ip);
+
+	LOGP(DRANAP, LOGL_DEBUG, "Assigning RAB: rab_id=%d, ggsn_ip=%x,"
+	     " teid_gn=%x, use_x213_nsap=%d\n",
+	     rab_id, ggsn_ip, pdp->lib->teid_gn, use_x213_nsap);
+
+	msg = ranap_new_msg_rab_assign_data(rab_id, ggsn_ip,
+					    pdp->lib->teid_gn, use_x213_nsap);
+	msg->l2h = msg->data;
+	return ranap_iu_rab_act(uectx, msg);
+}
+
+
+/* Main entry point for incoming 04.08 GPRS messages from Iu */
+int gsm0408_gprs_rcvmsg_iu(struct msgb *msg, struct gprs_ra_id *ra_id,
+			   uint16_t *sai)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	uint8_t pdisc = gsm48_hdr_pdisc(gh);
+	struct sgsn_mm_ctx *mmctx;
+	int rc = -EINVAL;
+
+	mmctx = sgsn_mm_ctx_by_ue_ctx(MSG_IU_UE_CTX(msg));
+	if (mmctx) {
+		rate_ctr_inc(&mmctx->ctrg->ctr[GMM_CTR_PKTS_SIG_IN]);
+		if (ra_id)
+			memcpy(&mmctx->ra, ra_id, sizeof(mmctx->ra));
+	}
+
+	/* MMCTX can be NULL */
+
+	switch (pdisc) {
+	case GSM48_PDISC_MM_GPRS:
+		rc = gsm0408_rcv_gmm(mmctx, msg, NULL, false);
+#pragma message "set drop_cipherable arg for gsm0408_rcv_gmm() from IuPS?"
+		break;
+	case GSM48_PDISC_SM_GPRS:
+		rc = gsm0408_rcv_gsm(mmctx, msg, NULL);
+		break;
+	default:
+		LOGMMCTXP(LOGL_NOTICE, mmctx,
+			"Unknown GSM 04.08 discriminator 0x%02x: %s\n",
+			pdisc, osmo_hexdump((uint8_t *)gh, msgb_l3len(msg)));
+		/* FIXME: return status message */
+		break;
+	}
+
+	/* MMCTX can be invalid */
+
+	return rc;
+}
+#endif
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index 829204ea9..ee1902c2c 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -50,10 +50,6 @@
 
 #include "../../bscconfig.h"
 
-#if BUILD_IU
-#include <osmocom/ranap/iu_client.h>
-#endif
-
 #define GPRS_LLME_CHECK_TICK 30
 
 extern struct sgsn_instance *sgsn;
diff --git a/src/gprs/sgsn_libgtp.c b/src/gprs/sgsn_libgtp.c
index a8ad527bc..5e3f48f3f 100644
--- a/src/gprs/sgsn_libgtp.c
+++ b/src/gprs/sgsn_libgtp.c
@@ -50,11 +50,7 @@
 #include <osmocom/sgsn/gprs_gmm.h>
 #include <osmocom/sgsn/gprs_subscriber.h>
 #include <osmocom/sgsn/gprs_sndcp.h>
-
-#ifdef BUILD_IU
-#include <osmocom/ranap/iu_client.h>
-#include <osmocom/ranap/ranap_ies_defs.h>
-#endif
+#include <osmocom/sgsn/gprs_ranap.h>
 
 #include <gtp.h>
 #include <pdp.h>
@@ -359,7 +355,7 @@ static const struct cause_map gtp2sm_cause_map[] = {
 	{ 0, 0 }
 };
 
-static int send_act_pdp_cont_acc(struct sgsn_pdp_ctx *pctx)
+int send_act_pdp_cont_acc(struct sgsn_pdp_ctx *pctx)
 {
 	struct sgsn_signal_data sig_data;
 	int rc;
@@ -473,72 +469,6 @@ void sgsn_ggsn_echo_req(struct sgsn_ggsn_ctx *ggc)
 	gtp_echo_req(ggc->gsn, ggc->gtp_version, ggc, &ggc->remote_addr);
 }
 
-#ifdef BUILD_IU
-/* Callback for RAB assignment response */
-int sgsn_ranap_rab_ass_resp(struct sgsn_mm_ctx *ctx, RANAP_RAB_SetupOrModifiedItemIEs_t *setup_ies)
-{
-	uint8_t rab_id;
-	bool require_pdp_update = false;
-	struct sgsn_pdp_ctx *pdp = NULL;
-	RANAP_RAB_SetupOrModifiedItem_t *item = &setup_ies->raB_SetupOrModifiedItem;
-
-	rab_id = item->rAB_ID.buf[0];
-
-	pdp = sgsn_pdp_ctx_by_nsapi(ctx, rab_id);
-	if (!pdp) {
-		LOGP(DRANAP, LOGL_ERROR, "RAB Assignment Response for unknown RAB/NSAPI=%u\n", rab_id);
-		return -1;
-	}
-
-	if (item->transportLayerAddress) {
-		LOGPC(DRANAP, LOGL_INFO, " Setup: (%u/%s)", rab_id, osmo_hexdump(item->transportLayerAddress->buf,
-								     item->transportLayerAddress->size));
-		switch (item->transportLayerAddress->size) {
-		case 7:
-			/* It must be IPv4 inside a X213 NSAP */
-			memcpy(pdp->lib->gsnlu.v, &item->transportLayerAddress->buf[3], 4);
-			break;
-		case 4:
-			/* It must be a raw IPv4 address */
-			memcpy(pdp->lib->gsnlu.v, item->transportLayerAddress->buf, 4);
-			break;
-		case 16:
-			/* TODO: It must be a raw IPv6 address */
-		case 19:
-			/* TODO: It must be IPv6 inside a X213 NSAP */
-		default:
-			LOGP(DRANAP, LOGL_ERROR, "RAB Assignment Resp: Unknown "
-				"transport layer address size %u\n",
-				item->transportLayerAddress->size);
-			return -1;
-		}
-		require_pdp_update = true;
-	}
-
-	/* The TEI on the RNC side might have changed, too */
-	if (item->iuTransportAssociation &&
-	    item->iuTransportAssociation->present == RANAP_IuTransportAssociation_PR_gTP_TEI &&
-	    item->iuTransportAssociation->choice.gTP_TEI.buf &&
-	    item->iuTransportAssociation->choice.gTP_TEI.size >= 4) {
-		uint32_t tei = osmo_load32be(item->iuTransportAssociation->choice.gTP_TEI.buf);
-		LOGP(DRANAP, LOGL_DEBUG, "Updating TEID on RNC side from 0x%08x to 0x%08x\n",
-			pdp->lib->teid_own, tei);
-		pdp->lib->teid_own = tei;
-		require_pdp_update = true;
-	}
-
-	if (require_pdp_update)
-		gtp_update_context(pdp->ggsn->gsn, pdp->lib, pdp, &pdp->lib->hisaddr0);
-
-	if (pdp->state != PDP_STATE_CR_CONF) {
-		send_act_pdp_cont_acc(pdp);
-		pdp->state = PDP_STATE_CR_CONF;
-	}
-	return 0;
-
-}
-#endif
-
 /* Confirmation of a PDP Context Delete */
 static int delete_pdp_conf(struct pdp_t *pdp, void *cbp, int cause)
 {
diff --git a/src/gprs/sgsn_main.c b/src/gprs/sgsn_main.c
index 9f2e11179..eef5f8f22 100644
--- a/src/gprs/sgsn_main.c
+++ b/src/gprs/sgsn_main.c
@@ -57,6 +57,7 @@
 #include <osmocom/sgsn/sgsn.h>
 #include <osmocom/sgsn/gprs_llc.h>
 #include <osmocom/sgsn/gprs_gmm.h>
+#include <osmocom/sgsn/gprs_ranap.h>
 
 #include <osmocom/ctrl/control_if.h>
 #include <osmocom/ctrl/ports.h>
@@ -354,10 +355,6 @@ static const struct log_info gprs_log_info = {
 	.num_cat = ARRAY_SIZE(gprs_categories),
 };
 
-#if BUILD_IU
-int sgsn_ranap_iu_event(struct ranap_ue_conn_ctx *ctx, enum ranap_iu_event_type type, void *data);
-#endif
-
 static bool file_exists(const char *path)
 {
 	struct stat sb;
diff --git a/tests/sgsn/Makefile.am b/tests/sgsn/Makefile.am
index 956ef8d8f..ae397b3c6 100644
--- a/tests/sgsn/Makefile.am
+++ b/tests/sgsn/Makefile.am
@@ -45,6 +45,7 @@ sgsn_test_LDADD = \
 	$(top_builddir)/src/gprs/gprs_llc_parse.o \
 	$(top_builddir)/src/gprs/gprs_llc.o \
 	$(top_builddir)/src/gprs/crc24.o \
+	$(top_builddir)/src/gprs/gprs_ranap.o \
 	$(top_builddir)/src/gprs/gprs_sndcp.o \
 	$(top_builddir)/src/gprs/gprs_gmm_attach.o \
 	$(top_builddir)/src/gprs/gprs_gmm.o \