Idea of restricting IP Access and PHP code

I wrote my own website that day and thought about the IP address restriction function. At least I should be able to set the IP address to be restricted in the background, and I should be able to restrict the IP address segment, such as 192.168.0. * The entire segment can be restricted in the same way. The simple code is as follows: (the DB class in phplib is used in the Program)

<? PHP
/*************************************** ******
* File: limitip. php
* Purpose: IP address restriction Program
* Version: V1.0
* Date:
* Author: heiyeluren (heiyeluren@163.com)
* Copyright: http://www.unixsky.net
**************************************** *****/

Error_reporting (7 );
Session_start ();

// Send character header information
If ($ headercharset)
Header ("Content-Type: text/html; charset = gb2312 ");

// Load public files
Require_once ("config. php ");
Require_once ("Global. php ");
Require_once ("db_mysql.php ");

/***************** Check whether the client can access the website ************/

// Obtain the Client IP Address
If (getenv ('HTTP _ client_ip ')){
$ Client_ip = getenv ('HTTP _ client_ip ');
} Elseif (getenv ('HTTP _ x_forwarded_for ')){
$ Client_ip = getenv ('HTTP _ x_forwarded_for ');
} Elseif (getenv ('remote _ ADDR ')){
$ Client_ip = getenv ('remote _ ADDR ');
} Else {
$ Client_ip = $ http_server_vars ['remote _ ADDR '];
}

// Break down the Client IP Address
$ CIP = explode (".", $ client_ip );

// Connect to the database
$ Db = new db_ SQL ();
$ Err = $ db-> connect ();

/* Restrict access from remote IP addresses. PS: This code is dizzy. It uses 8 If ,-_-#*/
// Extract the restricted IP address from the database
$ Query_str = "select limit_ip from us_limitip ";
$ Db-> query ($ query_str );
// Cyclically extract the results for verification.
While ($ db-> next_record ())
{
$ Limit_ip = $ db-> F ("limit_ip ");
$ Lip = explode (".", $ limit_ip );
// If the first IP address to be restricted is * or 0, it will jump to the error page.
If ($ lip [0] = '*') | ($ lip [0] = '0 '))
Header ("Location:.../error. php? Errid = 300 ");
// If the client IP address is equal to the IP address limit, it will jump to the error page.
If ($ client_ip = $ limit_ip)
Header ("Location:.../error. php? Errid = 300 ");
// If the first group of IP addresses are consistent, match the second group of IP addresses
If ($ CIP [0] = $ lip [0])
{
// If the second group limits IP addresses *, the page jumps to the error page.
If ($ lip [1] = '*')
Header ("Location:.../error. php? Errid = 300 ");
// Match the second group of IP addresses.
If ($ CIP [1] = $ lip [1])
{
// Jump to the error page if the third character group is *
If ($ lip [2] = '*')
Header ("Location:.../error. php? Errid = 300 ");
// If the third group of IP addresses matches, the request is forwarded to the third group for verification.
If ($ CIP [2] = $ lip [2])
{
// If the fourth group of restricted IP addresses is * or 0, the page will jump to the error page.
If ($ lip [3] = '*') | ($ lip [3] = '0 '))
Header ("Location:.../error. php? Errid = 300 ");
}
}
}
}
// Release the database query results
$ Db-> free ();

******************/

?>

The code is just one of my initial ideas, and there must be some shortcomings. If you have better suggestions, please don't hesitate to give me some advice!