CREATE OR REPLACE FUNCTION isvalidip (ipaddr VARCHAR2)
   RETURN NUMBER
IS
   tmpvar                 NUMBER;
   v_IPaddr VARCHAR2(64);
   v_validip              INT;
   v_pos1                 NUMBER;
   v_pos2                 NUMBER;
   v_pos3                 NUMBER;
   v_pos4                 NUMBER;
   v_len                  NUMBER;
   v_found_invalid_char   NUMBER;

BEGIN
   tmpvar := 0;
   v_IPaddr := ipaddr;

   -- If the IP address is NULL, check if the node name contains a valid IP address
   IF (v_ipaddr IS NULL OR v_ipaddr = '' OR v_ipaddr = ' ')
   THEN
      RETURN 0;
   END IF;

   -- Check if IP address is valid, if not set IP address to NULL.
   v_validip := 0;
   -- Trim leading and trailing spaces, if any
   v_ipaddr := RTRIM (LTRIM (v_ipaddr));
   -- Make sure there are no invalid characters
   v_found_invalid_char := 0;

   FOR i IN 1 .. LENGTH (v_ipaddr)
   LOOP
      IF (INSTR ('.0123456789', SUBSTR (v_ipaddr, i, 1)) = 0)
      THEN
         v_found_invalid_char := 1;
         EXIT;
      END IF;
   END LOOP;

   IF (v_found_invalid_char = 0)
   THEN
      -- Get dot positions
      v_pos1 := INSTR (v_ipaddr, '.');
      v_len := LENGTH (v_ipaddr);
      v_pos2 := v_pos1 + INSTR (SUBSTR (v_ipaddr, - (v_len - v_pos1)), '.');
      v_pos3 := v_pos2 + INSTR (SUBSTR (v_ipaddr, - (v_len - v_pos2)), '.');
      -- Check for extra dot positions
      v_pos4 := v_pos3 + INSTR (SUBSTR (v_ipaddr, - (v_len - v_pos3)), '.');

      -- Check for at least one character and a value less than 255
      IF (    v_pos1 > 1
          AND v_pos2 - v_pos1 > 1
          AND v_pos3 - v_pos2 > 1
          AND v_len - v_pos3 > 0
          AND v_pos4 = v_pos3
         )
      THEN
         IF     (TO_NUMBER (SUBSTR (v_ipaddr, 1, v_pos1 - 1)) <= 255)
            AND (TO_NUMBER (SUBSTR (v_ipaddr, v_pos1 + 1, v_pos2 - v_pos1 - 1)) <=
                                                                           255
                )
            AND (TO_NUMBER (SUBSTR (v_ipaddr, v_pos2 + 1, v_pos3 - v_pos2 - 1)) <=
                                                                           255
                )
            AND (TO_NUMBER (SUBSTR (v_ipaddr, v_pos3 + 1, v_len - v_pos3)) <=
                                                                           255
                )
         THEN
            v_validip := 1;
         END IF;
      END IF;
   END IF;

   /* If IP address in not valid, set it to NULL */
   IF v_validip <> 0
   THEN
      RETURN 1;
      v_ipaddr := NULL;
   END IF;

   RETURN 0;
EXCEPTION
   WHEN NO_DATA_FOUND
   THEN
      NULL;
   WHEN OTHERS
   THEN
      -- Consider logging the error and then re-raise
      RAISE;
END isvalidip;
/