ranap_rab_ass: add function to check if RAB is in FailureList

A RANAP RAB-AssignmentResponse may contain a FailedList. In order to
detect that a RAB Assignment failed at the HNB we need to be able to
check if the RAB we are dealing with is contained an such a FailedList.

Change-Id: I4319f7caa45ea758ccd792cc8570521df075cf45
Related: OS#5152

include/osmocom/hnbgw/ranap_rab_ass.h

@@ -14,3 +14,5 @@ int ranap_rab_ass_req_ies_replace_inet_addr(RANAP_RAB_AssignmentRequestIEs_t *ie
 					    uint8_t rab_id);
 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_resp_ies_check_failure(RANAP_RAB_AssignmentResponseIEs_t *ies, uint8_t rab_id);

src/osmo-hnbgw/ranap_rab_ass.c

@@ -141,8 +141,7 @@ static RANAP_IE_t *setup_or_modif_item_from_rab_ass_resp(const RANAP_RAB_Assignm
 {
 	/* Make sure we indeed deal with a setup-or-modified list */
 	if (!(ies->presenceMask & RAB_ASSIGNMENTRESPONSEIES_RANAP_RAB_SETUPORMODIFIEDLIST_PRESENT)) {
-		RANAP_DEBUG
-		    ("Decoding failed, the RANAP RAB AssignmentResponse did not contain a setup-or-modified list!\n");
+		RANAP_DEBUG("RANAP RAB AssignmentResponse did not contain a setup-or-modified list!\n");
 		return NULL;
 	}
 
@@ -153,6 +152,23 @@ static RANAP_IE_t *setup_or_modif_item_from_rab_ass_resp(const RANAP_RAB_Assignm
 	return ies->raB_SetupOrModifiedList.raB_SetupOrModifiedList_ies.list.array[index];
 }
 
+/* Pick the indexed item from the RAB failed list and return a pointer to it */
+static RANAP_IE_t *failed_list_item_from_rab_ass_resp(const RANAP_RAB_AssignmentResponseIEs_t *ies,
+						      unsigned int index)
+{
+	/* Make sure we indeed deal with a failed list */
+	if (!(ies->presenceMask & RAB_ASSIGNMENTRESPONSEIES_RANAP_RAB_FAILEDLIST_PRESENT)) {
+		RANAP_DEBUG("RANAP RAB AssignmentResponse did not contain a failed list!\n");
+		return NULL;
+	}
+
+	/* Detect the end of the list */
+	if (index >= ies->raB_FailedList.raB_FailedList_ies.list.count)
+		return NULL;
+
+	return ies->raB_FailedList.raB_FailedList_ies.list.array[index];
+}
+
 /* find the RAB specified by rab_id in ies and when found, decode the result into items_ies */
 static int decode_rab_smditms_from_resp_ies(RANAP_RAB_SetupOrModifiedItemIEs_t *items_ies,
 					    RANAP_RAB_AssignmentResponseIEs_t *ies, uint8_t rab_id)
@@ -184,6 +200,37 @@ static int decode_rab_smditms_from_resp_ies(RANAP_RAB_SetupOrModifiedItemIEs_t *
 	}
 }
 
+/* See comment above decode_rab_smditms_from_resp_ies() */
+static int decode_rab_flitms_from_resp_ies(RANAP_RAB_FailedItemIEs_t *items_ies,
+					   RANAP_RAB_AssignmentResponseIEs_t *ies, uint8_t rab_id)
+{
+	RANAP_IE_t *failed_list_ie;
+	RANAP_RAB_FailedItem_t *rab_failed_item;
+	int rc;
+	uint8_t rab_id_decoded;
+	unsigned int index = 0;
+
+	while (1) {
+		failed_list_ie = failed_list_item_from_rab_ass_resp(ies, index);
+		if (!failed_list_ie)
+			return -EINVAL;
+
+		rc = ranap_decode_rab_faileditemies_fromlist(items_ies, &failed_list_ie->value);
+		if (rc < 0)
+			return -EINVAL;
+
+		rab_failed_item = &items_ies->raB_FailedItem;
+		/* 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_failed_item->rAB_ID.buf[0];
+		if (rab_id_decoded == rab_id)
+			return index;
+
+		ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RANAP_RAB_FailedItem, items_ies);
+		index++;
+	}
+}
+
 /* find the RAB specified by rab_id in ies and when found, decode the result into item */
 static int decode_rab_smditms_from_req_ies(RANAP_RAB_SetupOrModifyItemFirst_t *item,
 					   RANAP_RAB_AssignmentRequestIEs_t *ies, uint8_t rab_id)
@@ -477,3 +524,25 @@ error:
 
 	return rc;
 }
+
+/*! Check if a specific RAB is present in an RAB-Failed-Item-List inside RANAP_RAB_AssignmentResponseIEs.
+ *  \ptmap[in] ies user provided memory with RANAP_RAB_AssignmentResponseIEs.
+ *  \ptmap[in] rab_id expected rab id to look for.
+ *  \returns true when RAB could be identified as failed; false otherwise */
+bool ranap_rab_ass_resp_ies_check_failure(RANAP_RAB_AssignmentResponseIEs_t *ies, uint8_t rab_id)
+{
+	RANAP_RAB_FailedItemIEs_t _rab_failed_items_ies;
+	RANAP_RAB_FailedItemIEs_t *rab_failed_items_ies = &_rab_failed_items_ies;
+	int rc;
+	bool result = true;
+
+	/* If we can get a failed item for the specified RAB ID, then we know that the
+	 * HNB reported the RAB Assignment as failed */
+	rc = decode_rab_flitms_from_resp_ies(rab_failed_items_ies, ies, rab_id);
+	if (rc < 0)
+		result = false;
+
+	ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RANAP_RAB_FailedItem, rab_failed_items_ies);
+
+	return result;
+}

tests/ranap_rab_ass/ranap_rab_ass_test.c

@@ -269,6 +269,32 @@ void test_ranap_rab_ass_resp_replace_inet_addr(void)
 	ranap_cn_rx_co_free(&message);
 }
 
+void test_ranap_rab_ass_resp_ies_check_failure(void)
+{
+	int rc;
+	ranap_message message;
+	bool rab_failed_at_hnb;
+	uint8_t testvec[] = {
+		0x60, 0x00, 0x00, 0x11, 0x00, 0x00, 0x01, 0x00,
+		0x23, 0x40, 0x0a, 0x00, 0x00, 0x01, 0x00, 0x22,
+		0x40, 0x03, 0x05, 0xd0, 0x00
+	};
+
+	rc = ranap_cn_rx_co_decode(talloc_asn1_ctx, &message, testvec, sizeof(testvec));
+	OSMO_ASSERT(rc == 0);
+
+	rab_failed_at_hnb =
+		ranap_rab_ass_resp_ies_check_failure(&message.msg.raB_AssignmentResponseIEs, 23);
+	printf("ranap_rab_ass_resp_ies_check_failure rab_failed_at_hnb=%u (RAB ID 23)\n", rab_failed_at_hnb);
+
+	rab_failed_at_hnb =
+		ranap_rab_ass_resp_ies_check_failure(&message.msg.raB_AssignmentResponseIEs, 44);
+	printf("ranap_rab_ass_resp_ies_check_failure rab_failed_at_hnb=%u (RAB ID 44, which is not in the message)\n",
+	       rab_failed_at_hnb);
+
+	ranap_cn_rx_co_free(&message);
+}
+
 static const struct log_info_cat log_cat[] = {
 	[DRANAP] = {
 		    .name = "RANAP", .loglevel = LOGL_DEBUG, .enabled = 1,
@@ -329,6 +355,7 @@ int main(int argc, char **argv)
 	test_ranap_rab_ass_resp_extract_inet_addr();
 	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_cleanup();
 	return 0;

tests/ranap_rab_ass/ranap_rab_ass_test.ok

@@ -14,3 +14,5 @@ after: addr=1.2.3.4, port=1234, rab_id=39
 before: addr=10.9.1.164, port=1034
 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)