mme: s1ap: Implement tx of MME DIRECT INFORMATION TRANSFER

Triggered when receiving a GTPv1C RAN Information Relay message on
Gn interface, targeted at one of the eNBs under the MME.

src/mme/mme-gn-handler.c

@@ -29,6 +29,8 @@
 #include "mme-gn-build.h"
 #include "mme-gn-handler.h"
 
+#include "s1ap-path.h"
+
 void mme_gn_handle_echo_request(
         ogs_gtp_xact_t *xact, ogs_gtp1_echo_request_t *req)
 {
@@ -46,10 +48,97 @@ void mme_gn_handle_echo_response(
     /* Not Implemented */
 }
 
+static int decode_global_enb_id(S1AP_Global_ENB_ID_t *glob_enb_id, const uint8_t *buf, size_t buf_len)
+{
+    asn_dec_rval_t dec_ret = {0};
 
+    memset(glob_enb_id, 0, sizeof(S1AP_Global_ENB_ID_t));
+    dec_ret = aper_decode(NULL, &asn_DEF_S1AP_Global_ENB_ID, (void **)&glob_enb_id,
+            buf, buf_len, 0, 0);
+
+    if (dec_ret.code != RC_OK) {
+        ogs_warn("Failed to decode ASN-PDU [code:%d,consumed:%d]",
+                dec_ret.code, (int)dec_ret.consumed);
+        return OGS_ERROR;
+    }
+
+    if (ogs_log_get_domain_level(OGS_LOG_DOMAIN) >= OGS_LOG_TRACE)
+        asn_fprint(stdout, &asn_DEF_S1AP_Global_ENB_ID, glob_enb_id);
+
+    return OGS_OK;
+}
+
+/* TS 29.060 7.5.14.1 */
 void mme_gn_handle_ran_information_relay(
         ogs_gtp_xact_t *xact, ogs_gtp1_ran_information_relay_t *req)
 {
+    uint8_t discr;
+    ogs_eps_tai_t *target_tai;
+    S1AP_Global_ENB_ID_t global_ENB_ID;
+    uint32_t target_enb_id;
+    mme_enb_t *target_enb = NULL;
+    int rv;
+
     ogs_debug("[Gn] Receiving RAN Information Relay");
-    /* Not Implemented */
+
+    if (req->ran_transparent_container.len == 0 ||
+        req->ran_transparent_container.data == NULL) {
+        ogs_warn("[Gn] Receiving RAN Information Relay with empty container!");
+        return;
+    }
+
+    /* "If RIM Routing Address Discriminator IE is not included, the RIM Routing
+     * Address shall be processed as an RNC identifier". Hence, not for us! */
+    if (req->rim_routing_address_discriminator.presence == false) {
+        ogs_warn("[Gn] Rx RAN Information Relay: no RIM Routing Address Discriminator!");
+        return;
+    }
+
+    if (req->rim_routing_address_discriminator.len != 1) {
+        ogs_warn("[Gn] Rx RAN Information Relay: RIM Routing Address Discriminator len != 1");
+        return;
+    }
+
+    /* 3GPP TS 48.018 RIM Routing Information IE */
+    discr = *((uint8_t*)req->rim_routing_address_discriminator.data) & 0x0f;
+    if (discr != 2) {/* 2: An eNB identifier is used to identify an E-UTRAN eNodeB or HeNB */
+        ogs_warn("[Gn] Rx RAN Information Relay: RIM Routing Address Discriminator %u unexpected", discr);
+        return;
+    }
+
+    if (req->rim_routing_address.presence == false) {
+        ogs_warn("[Gn] Rx RAN Information Relay: no RIM Routing Address!");
+        return;
+    }
+
+    if (req->rim_routing_address.len < sizeof(ogs_eps_tai_t)) {
+        ogs_warn("[Gn] Rx RAN Information Relay: RIM Routing Address len < %zu", sizeof(ogs_eps_tai_t));
+        return;
+    }
+    target_tai = req->rim_routing_address.data;
+
+    rv = decode_global_enb_id(&global_ENB_ID,
+            ((uint8_t *)req->rim_routing_address.data) + sizeof(ogs_eps_tai_t),
+            req->rim_routing_address.len - sizeof(ogs_eps_tai_t));
+    if (rv != OGS_OK)
+        return;
+    ogs_s1ap_ENB_ID_to_uint32(&global_ENB_ID.eNB_ID, &target_enb_id);
+
+    ogs_debug("    Target : ENB_ID[%s:%d], TAC[%d]",
+              global_ENB_ID.eNB_ID.present ==
+                  S1AP_ENB_ID_PR_homeENB_ID ? "Home" :
+              global_ENB_ID.eNB_ID.present ==
+                  S1AP_ENB_ID_PR_macroENB_ID ? "Macro" : "Others",
+              target_enb_id, target_tai->tac);
+
+    target_enb = mme_enb_find_by_enb_id(target_enb_id);
+    if (target_enb == NULL) {
+        ogs_warn("[Gn] Rx RAN Information Relay: cannot find target eNB-id[0x%x]", target_enb_id);
+        return;
+    }
+
+    s1ap_send_mme_direct_information_transfer(
+        target_enb,
+        req->ran_transparent_container.data,
+        req->ran_transparent_container.len);
 }

src/mme/s1ap-build.c

@@ -1559,6 +1559,60 @@ ogs_pkbuf_t *s1ap_build_mme_configuration_transfer(
     return ogs_s1ap_encode(&pdu);
 }
 
+/* 3GPP TS 36.413 8.14 MME Direct Information Transfer */
+ogs_pkbuf_t *s1ap_build_direct_information_transfer(const uint8_t *buf, size_t buf_len)
+{
+    S1AP_S1AP_PDU_t pdu;
+    S1AP_InitiatingMessage_t *initiatingMessage = NULL;
+    S1AP_MMEDirectInformationTransfer_t *MMEDirectInformationTransfer = NULL;
+
+    S1AP_MMEDirectInformationTransferIEs_t *ie = NULL;
+    S1AP_Inter_SystemInformationTransferType_t *Inter_SystemInformationTransferType = NULL;
+    S1AP_RIMTransfer_t *rIMTransfer = NULL;
+
+    ogs_assert(buf);
+    ogs_assert(buf_len > 0);
+
+    ogs_debug("MMEDirectInformationTransfer");
+
+    memset(&pdu, 0, sizeof (S1AP_S1AP_PDU_t));
+    pdu.present = S1AP_S1AP_PDU_PR_initiatingMessage;
+    pdu.choice.initiatingMessage = CALLOC(1, sizeof(S1AP_InitiatingMessage_t));
+
+    initiatingMessage = pdu.choice.initiatingMessage;
+    initiatingMessage->procedureCode =
+        S1AP_ProcedureCode_id_MMEDirectInformationTransfer;
+    initiatingMessage->criticality = S1AP_Criticality_ignore;
+    initiatingMessage->value.present =
+        S1AP_InitiatingMessage__value_PR_MMEDirectInformationTransfer;
+
+    MMEDirectInformationTransfer =
+        &initiatingMessage->value.choice.MMEDirectInformationTransfer;
+
+    ie = CALLOC(1, sizeof(S1AP_MMEDirectInformationTransferIEs_t));
+    ASN_SEQUENCE_ADD(&MMEDirectInformationTransfer->protocolIEs, ie);
+
+    ie->id = S1AP_ProtocolIE_ID_id_Inter_SystemInformationTransferTypeMDT;
+    ie->criticality = S1AP_Criticality_reject;
+    ie->value.present =
+        S1AP_MMEDirectInformationTransferIEs__value_PR_Inter_SystemInformationTransferType;
+
+    Inter_SystemInformationTransferType = &ie->value.choice.Inter_SystemInformationTransferType;
+    Inter_SystemInformationTransferType->present = S1AP_Inter_SystemInformationTransferType_PR_rIMTransfer;
+
+    Inter_SystemInformationTransferType->choice.rIMTransfer = CALLOC(1, sizeof(S1AP_RIMTransfer_t));
+    rIMTransfer = Inter_SystemInformationTransferType->choice.rIMTransfer;
+
+    rIMTransfer->rIMInformation.size = buf_len;
+    rIMTransfer->rIMInformation.buf = CALLOC(buf_len, sizeof(uint8_t));
+    memcpy(rIMTransfer->rIMInformation.buf, buf, buf_len);
+
+	/* "The RIM Routing Address IE shall not be present since the eNB is the final destination node": */
+    rIMTransfer->rIMRoutingAddress = NULL;
+
+    return ogs_s1ap_encode(&pdu);
+}
+
 ogs_pkbuf_t *s1ap_build_path_switch_ack(
         mme_ue_t *mme_ue, bool e_rab_to_switched_in_uplink_list)
 {

src/mme/s1ap-build.h

@@ -56,6 +56,8 @@ ogs_pkbuf_t *s1ap_build_paging(
 ogs_pkbuf_t *s1ap_build_mme_configuration_transfer(
     S1AP_SONConfigurationTransfer_t *son_configuration_transfer);
 
+ogs_pkbuf_t *s1ap_build_direct_information_transfer(const uint8_t *buf, size_t buf_len);
+
 ogs_pkbuf_t *s1ap_build_path_switch_ack(
         mme_ue_t *mme_ue, bool e_rab_to_switched_in_uplink_list);
 ogs_pkbuf_t *s1ap_build_path_switch_failure(

src/mme/s1ap-path.c

@@ -489,6 +489,31 @@ int s1ap_send_mme_configuration_transfer(
     return rv;
 }
 
+int s1ap_send_mme_direct_information_transfer(
+        mme_enb_t *target_enb, const uint8_t *buf, size_t buf_len)
+{
+    int rv;
+    ogs_pkbuf_t *s1apbuf = NULL;
+
+    ogs_debug("Tx MME Direct Information Transfer");
+
+    if (!mme_enb_cycle(target_enb)) {
+        ogs_error("eNB has already been removed");
+        return OGS_NOTFOUND;
+    }
+
+    s1apbuf = s1ap_build_direct_information_transfer(buf, buf_len);
+    if (!s1apbuf) {
+        ogs_error("s1ap_build_direct_information_transfer() failed");
+        return OGS_ERROR;
+    }
+
+    rv = s1ap_send_to_enb(target_enb, s1apbuf, S1AP_NON_UE_SIGNALLING);
+    ogs_expect(rv == OGS_OK);
+
+    return rv;
+}
+
 int s1ap_send_e_rab_modification_confirm(mme_ue_t *mme_ue)
 {
     int rv;

src/mme/s1ap-path.h

@@ -64,6 +64,9 @@ int s1ap_send_mme_configuration_transfer(
         mme_enb_t *target_enb,
         S1AP_SONConfigurationTransfer_t *SONConfigurationTransfer);
 
+int s1ap_send_mme_direct_information_transfer(
+        mme_enb_t *target_enb, const uint8_t *buf, size_t buf_len);
+
 int s1ap_send_e_rab_modification_confirm(mme_ue_t *mme_ue);
 
 int s1ap_send_path_switch_ack(