Merge remote-tracking branch 'origin/issue-801' into integration_2025_w23 (!3302)

Enhance UE identity management in Initial UE Message and other NGAP improvements

This MR improves the Initial UE Message procedures by supporting simultaneous
presence of both 5G-S-TMSI and GUAMI. Previously, only one identity could be
used, leading to potential AMF selection failures. Now the presenceMask allows
both identities. The AMF selection is prioritizing GUAMI first, then falling
back to 5G-S-TMSI, and finally using PLMN or highest capacity.

Also, fix handling of selected PLMN identity in NGAP.

Refactoring:
- Select the AMF based on (1) absence of UE Identity (2) Presence of GUAMI
  (3) Presence of 5G-S-TMSI
- Also refactored the AMF selection logic for better readability and reliability.
- Refactor and cleanup rrc_gNB_send_NGAP_NAS_FIRST_REQ
- Replace ngap_pdu_t with byte_array_t
- Add guami_t to ngran_types.h: refactor NGAP and RRC code to use one common
  GUAMI type instead of two identical ones

Also:
- Bugfix in ngap_gNB_handle_ng_setup_response: use correct count for PLMNSupportList

Closes issue #801

common/5g_platform_types.h

@@ -35,6 +35,16 @@ typedef struct nssai_s {
   uint32_t sd;
 } nssai_t;
 
+// Globally Unique AMF Identifier
+typedef struct nr_guami_s {
+  uint16_t mcc;
+  uint16_t mnc;
+  uint8_t mnc_len;
+  uint8_t amf_region_id;
+  uint16_t amf_set_id;
+  uint8_t amf_pointer;
+} nr_guami_t;
+
 typedef enum { NON_DYNAMIC, DYNAMIC } fiveQI_t;
 
 #endif

common/utils/ds/byte_array.c

@@ -23,15 +23,21 @@
 
 #include <assert.h>
 #include <string.h>
+#include "common/utils/utils.h" // for malloc_or_fail
+
+byte_array_t create_byte_array(const size_t len, const uint8_t* buffer)
+{
+  byte_array_t result = {.len = len};
+  if (len) {
+    result.buf = malloc_or_fail(len);
+    memcpy(result.buf, buffer, len);
+  }
+  return result;
+}
 
 byte_array_t copy_byte_array(byte_array_t src)
 {
-  byte_array_t dst = {0};
-  dst.buf = malloc(src.len);
-  assert(dst.buf != NULL && "Memory exhausted");
-  memcpy(dst.buf, src.buf, src.len);
-  dst.len = src.len;
-  return dst;
+  return create_byte_array(src.len, src.buf);
 }
 
 void free_byte_array(byte_array_t ba)

common/utils/ds/byte_array.h

@@ -28,6 +28,13 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define FREE_AND_ZERO_BYTE_ARRAY(BA) \
+  do {                               \
+    free_byte_array(BA);             \
+    BA.buf = NULL;                   \
+    BA.len = 0;                      \
+  } while (0)
+
 typedef struct {
   size_t len;
   uint8_t* buf;
@@ -43,5 +50,6 @@ bool eq_byte_array(const byte_array_t* m0, const byte_array_t* m1);
 
 byte_array_t cp_str_to_ba(const char* str);
 char* cp_ba_to_str(const byte_array_t ba);
+byte_array_t create_byte_array(const size_t len, const uint8_t* buffer);
 
 #endif