Refactor reading of NR cap from capability list

The next commit will modify the UE context setup request procedure to
(possibly) receive UE capabilities through Handover Preparation
Information, which extracts the UE capabilities for the UE to be setup.
To avoid code duplication, extract the code that will be needed in UE
capability extraction from Handover Preparation Information.

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -375,26 +375,16 @@ static int handle_ue_context_drbs_release(NR_UE_info_t *UE,
   return drbs_len;
 }
 
-static NR_UE_NR_Capability_t *get_ue_nr_cap(int rnti, uint8_t *buf, uint32_t len)
+static NR_UE_NR_Capability_t *get_nr_cap(const NR_UE_CapabilityRAT_ContainerList_t *clist)
 {
-  if (buf == NULL || len == 0)
-    return NULL;
-
-  NR_UE_CapabilityRAT_ContainerList_t *clist = NULL;
-  asn_dec_rval_t dec_rval = uper_decode(NULL, &asn_DEF_NR_UE_CapabilityRAT_ContainerList, (void **)&clist, buf, len, 0, 0);
-  if (dec_rval.code != RC_OK) {
-    LOG_W(NR_MAC, "cannot decode UE capability container list of UE RNTI %04x, ignoring capabilities\n", rnti);
-    return NULL;
-  }
-
-  NR_UE_NR_Capability_t *cap = NULL;
   for (int i = 0; i < clist->list.count; i++) {
     const NR_UE_CapabilityRAT_Container_t *c = clist->list.array[i];
-    if (cap != NULL || c->rat_Type != NR_RAT_Type_nr) {
-      LOG_W(NR_MAC, "UE RNTI %04x: ignoring capability of type %ld\n", rnti, c->rat_Type);
+    if (c->rat_Type != NR_RAT_Type_nr) {
+      LOG_W(NR_MAC, "ignoring capability of type %ld\n", c->rat_Type);
       continue;
     }
 
+    NR_UE_NR_Capability_t *cap = NULL;
     asn_dec_rval_t dec_rval = uper_decode(NULL,
                                           &asn_DEF_NR_UE_NR_Capability,
                                           (void **)&cap,
@@ -403,11 +393,29 @@ static NR_UE_NR_Capability_t *get_ue_nr_cap(int rnti, uint8_t *buf, uint32_t len
                                           0,
                                           0);
     if (dec_rval.code != RC_OK) {
-      LOG_W(NR_MAC, "cannot decode NR UE capabilities of UE RNTI %04x, ignoring NR capability\n", rnti);
-      cap = NULL;
+      LOG_W(NR_MAC, "cannot decode NR UE capability, ignoring\n");
+      ASN_STRUCT_FREE(asn_DEF_NR_UE_NR_Capability, cap);
       continue;
     }
+    return cap;
   }
+  return NULL;
+}
+
+static NR_UE_NR_Capability_t *get_ue_nr_cap(int rnti, uint8_t *buf, uint32_t len)
+{
+  if (buf == NULL || len == 0)
+    return NULL;
+
+  NR_UE_CapabilityRAT_ContainerList_t *clist = NULL;
+  asn_dec_rval_t dec_rval = uper_decode(NULL, &asn_DEF_NR_UE_CapabilityRAT_ContainerList, (void **)&clist, buf, len, 0, 0);
+  if (dec_rval.code != RC_OK) {
+    LOG_W(NR_MAC, "cannot decode UE capability container list of UE RNTI %04x, ignoring capabilities\n", rnti);
+    return NULL;
+  }
+
+  NR_UE_NR_Capability_t *cap = get_nr_cap(clist);
+  ASN_STRUCT_FREE(asn_DEF_NR_UE_CapabilityRAT_ContainerList, clist);
   return cap;
 }