add UE policy container decoder

src/nas/ies/Payload_Container.cpp

@@ -154,6 +154,20 @@ int Payload_Container::encode2buffer(uint8_t* buf, int len) {
 //------------------------------------------------------------------------------
 
 int Payload_Container::decodefrombuffer(uint8_t* buf, int len, bool is_option) {
+// 24.501 g80
+// In this version of the protocol, the UE can only include the Payload container
+// IE in the REGISTRATION REQUEST message to carry a payload of type "UE policy container".
+
+// "UE policy container", the UE policy container in the Payload container IE is
+// handled in the UE policy delivery procedures specified in Annex D.
+
+  int decoded_size = 0;
+  length =  *buf;
+  decoded_size++;
+  length |= (*(buf + decoded_size)) << 8;
+  //should decode UE STATE INDICATION here
+  decoded_size += length;
+  return decoded_size;
 }
 
 //------------------------------------------------------------------------------