ranap_rab_ass: add function to check if RAB is in ReleaseList

A RANAP RAB-AssignmentRelease may contain a ReleaseList. In order to
detect that a RAB is about to be released we need to be able to check if
the RAB we are dealing with is contained in such a ReleaseList.

Change-Id: I5b67cc2d35d11de7a09e66c181a1fdd5a58c75bb
Related: OS#5152

include/osmocom/hnbgw/ranap_rab_ass.h

@@ -15,4 +15,5 @@ int ranap_rab_ass_req_ies_replace_inet_addr(RANAP_RAB_AssignmentRequestIEs_t *ie
 int ranap_rab_ass_resp_ies_replace_inet_addr(RANAP_RAB_AssignmentResponseIEs_t *ies, struct osmo_sockaddr *addr,
 					     uint8_t rab_id);
 
+bool ranap_rab_ass_req_ies_check_release(RANAP_RAB_AssignmentRequestIEs_t *ies, uint8_t rab_id);
 bool ranap_rab_ass_resp_ies_check_failure(RANAP_RAB_AssignmentResponseIEs_t *ies, uint8_t rab_id);

src/osmo-hnbgw/ranap_rab_ass.c

@@ -135,6 +135,23 @@ static RANAP_ProtocolIE_FieldPair_t *prot_ie_field_pair_from_ass_req_ies(const R
 	return protocol_ie_field_pair;
 }
 
+/* Pick the indexed item from the RAB release-list list and return a pointer to it */
+static RANAP_IE_t *release_item_from_ass_req_ies(const RANAP_RAB_AssignmentRequestIEs_t *ies, unsigned int index)
+{
+	/* Make sure we indeed deal with a setup-or-modify list */
+	if (!(ies->presenceMask & RAB_ASSIGNMENTREQUESTIES_RANAP_RAB_RELEASELIST_PRESENT)) {
+		RANAP_DEBUG
+		    ("Decoding failed, the RANAP RAB AssignmentRequest did not contain a release list!\n");
+		return NULL;
+	}
+
+	/* Detect the end of the list */
+	if (index >= ies->raB_ReleaseList.raB_ReleaseList_ies.list.count)
+		return NULL;
+
+	return ies->raB_ReleaseList.raB_ReleaseList_ies.list.array[index];
+}
+
 /* Pick the indexed item from the RAB setup-or-modified list and return a pointer to it */
 static RANAP_IE_t *setup_or_modif_item_from_rab_ass_resp(const RANAP_RAB_AssignmentResponseIEs_t *ies,
 							 unsigned int index)
@@ -261,6 +278,41 @@ static int decode_rab_smditms_from_req_ies(RANAP_RAB_SetupOrModifyItemFirst_t *i
 	}
 }
 
+static int decode_rab_relitms_from_req_ies(RANAP_RAB_ReleaseItemIEs_t *items_ies,
+					   RANAP_RAB_AssignmentRequestIEs_t *ies, uint8_t rab_id)
+{
+	RANAP_IE_t *release_list_ie;
+	RANAP_RAB_ReleaseItem_t *rab_release_item;
+	int rc;
+	uint8_t rab_id_decoded;
+	unsigned int index = 0;
+
+	while (1) {
+		release_list_ie = release_item_from_ass_req_ies(ies, index);
+		if (!release_list_ie)
+			return -EINVAL;
+
+		if (release_list_ie->id != RANAP_ProtocolIE_ID_id_RAB_ReleaseItem) {
+			RANAP_DEBUG("Decoding failed, the protocol IE is not of type RANAP RAB ReleaseItem!\n");
+			return -EINVAL;
+		}
+
+		rc = ranap_decode_rab_releaseitemies_fromlist(items_ies, &release_list_ie->value);
+		if (rc < 0)
+			return -EINVAL;
+
+		rab_release_item = &items_ies->raB_ReleaseItem;
+		/* The RAB-ID is defined as a bitstring with a size of 8 (1 byte),
+		 * See also RANAP-IEs.asn, RAB-ID ::= BIT STRING (SIZE (8)) */
+		rab_id_decoded = rab_release_item->rAB_ID.buf[0];
+		if (rab_id_decoded == rab_id)
+			return index;
+
+		ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RANAP_RAB_ReleaseItem, items_ies);
+		index++;
+	}
+}
+
 /*! Extract IP address and port from RANAP_RAB_AssignmentRequestIEs.
  *  \ptmap[out] addr user provided memory to store extracted RTP stream IP-Address and port number.
  *  \ptmap[out] rab_id pointer to store RAB-ID (optional, can be NULL).
@@ -546,3 +598,25 @@ bool ranap_rab_ass_resp_ies_check_failure(RANAP_RAB_AssignmentResponseIEs_t *ies
 
 	return result;
 }
+
+/*! Check if a specific RAB is present in an RAB-ReleaseList inside RANAP_RAB_AssignmentRequestIEs.
+ *  \ptmap[in] ies user provided memory with RANAP_RAB_AssignmentRequestIEs.
+ *  \ptmap[in] rab_id expected rab id to look for.
+ *  \returns true when RAB is intended for release; false otherwise */
+bool ranap_rab_ass_req_ies_check_release(RANAP_RAB_AssignmentRequestIEs_t *ies, uint8_t rab_id)
+{
+	RANAP_RAB_ReleaseItemIEs_t _rab_release_items_ies;
+	RANAP_RAB_ReleaseItemIEs_t *rab_release_items_ies = &_rab_release_items_ies;
+	int rc;
+	bool result = true;
+
+	/* If we can get a rlease list item for the specified RAB ID, then we know that the
+	 * MSC intends to release the specified RAB */
+	rc = decode_rab_relitms_from_req_ies(rab_release_items_ies, ies, rab_id);
+	if (rc < 0)
+		result = false;
+
+	ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RANAP_RAB_ReleaseItem, rab_release_items_ies);
+
+	return result;
+}

tests/ranap_rab_ass/ranap_rab_ass_test.c

@@ -295,6 +295,31 @@ void test_ranap_rab_ass_resp_ies_check_failure(void)
 	ranap_cn_rx_co_free(&message);
 }
 
+void test_ranap_rab_ass_req_ies_check_release(void)
+{
+	int rc;
+	ranap_message message;
+	bool rab_release_req;
+	uint8_t testvec[] = {
+		0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x01, 0x00,
+		0x29, 0x40, 0x0a, 0x00, 0x00, 0x01, 0x00, 0x28,
+		0x40, 0x03, 0x05, 0xd0, 0x00
+	};
+
+	rc = ranap_ran_rx_co_decode(talloc_asn1_ctx, &message, testvec, sizeof(testvec));
+	OSMO_ASSERT(rc == 0);
+
+	rab_release_req =
+		ranap_rab_ass_req_ies_check_release(&message.msg.raB_AssignmentRequestIEs, 23);
+	printf("ranap_rab_ass_req_ies_check_release rab_release_req=%u (RAB ID 23)\n", rab_release_req);
+
+	rab_release_req =
+		ranap_rab_ass_req_ies_check_release(&message.msg.raB_AssignmentRequestIEs, 44);
+	printf("ranap_rab_ass_req_ies_check_release rab_release_req=%u (RAB ID 44, which is not in the message)\n", rab_release_req);
+
+	ranap_ran_rx_co_free(&message);
+}
+
 static const struct log_info_cat log_cat[] = {
 	[DRANAP] = {
 		    .name = "RANAP", .loglevel = LOGL_DEBUG, .enabled = 1,
@@ -356,6 +381,7 @@ int main(int argc, char **argv)
 	test_ranap_rab_ass_req_replace_inet_addr();
 	test_ranap_rab_ass_resp_replace_inet_addr();
 	test_ranap_rab_ass_resp_ies_check_failure();
+	test_ranap_rab_ass_req_ies_check_release();
 
 	test_cleanup();
 	return 0;

tests/ranap_rab_ass/ranap_rab_ass_test.ok

@@ -16,3 +16,5 @@ ranap_rab_ass_resp_replace_inet_addr rc=0
 after: addr=1.2.3.4, port=1234
 ranap_rab_ass_resp_ies_check_failure rab_failed_at_hnb=1 (RAB ID 23)
 ranap_rab_ass_resp_ies_check_failure rab_failed_at_hnb=0 (RAB ID 44, which is not in the message)
+ranap_rab_ass_req_ies_check_release rab_release_req=1 (RAB ID 23)
+ranap_rab_ass_req_ies_check_release rab_release_req=0 (RAB ID 44, which is not in the message)