PHP automatically jumps to pages in different regions based on IP addresses

To test, you need to download an IP database, and then save the php code I sent to the php file, and put the javascript code in the html file, to add more cities, you only need to copy elseif in javascript code several times to download an IP database, and then save the php code I sent as a php file, javascript code is put into the html file. to add more cities, you only need to copy else if in javascript code several times.
PHP code:

// Php ip retrieval algorithm
$ User_IP = ($ _ SERVER ["HTTP_VIA"])? $ _ SERVER ["HTTP_X_FORWARDED_FOR"]: $ _ SERVER ["REMOTE_ADDR"];
$ User_IP = ($ user_IP )? $ User_IP: $ _ SERVER ["REMOTE_ADDR"];
// Echo $ user_IP;
// ============================================
//
// Function: obtains the real address of an IP address.
// Parameter: $ ip-ip address
//
// ============================================
Function convertip ($ ip ){
// IP data file path, which can be modified as needed
$ Dat_path = 'IP. dat ';
// Check the IP address
If (! Ereg ("^ ([0-9] {1, 3}.) {3} [0-9] {1, 3} $", $ ip )){
Return 'IP Address error ';
}
// Open the IP data file
If (! $ Fd = @ fopen ($ dat_path, 'RB ')){
Return 'IP date file not exists or access denied ';
}
// Calculate the number of integers by decomposing IP addresses.
$ Ip = explode ('.', $ ip );
$ IpNum = $ ip [0] X 16777216 + $ ip [1] * 65536 + $ ip [2] * 256 + $ ip [3];
// Obtain the start and end locations of the IP address data index.
$ DataBegin = fread ($ fd, 4 );
$ DataEnd = fread ($ fd, 4 );
$ Ipbegin = implode (", unpack ('L', $ DataBegin ));
If ($ ipbegin <0) $ ipbegin + = pow (2, 32 );
$ Ipend = implode (", unpack ('L', $ DataEnd ));
If ($ ipend <0) $ ipend + = pow (2, 32 );
$ IpAllNum = ($ ipend-$ ipbegin)/7 + 1;
$ BeginNum = 0;
$ EndNum = $ ipAllNum;
// Use the binary search method to search for matched IP records from index records
While ($ ip1num> $ ipNum | $ ip2num <$ ipNum ){
$ Middle = intval ($ EndNum + $ BeginNum)/2 );
// Read 4 bytes from the offset pointer to the index position
Fseek ($ fd, $ ipbegin + 7 * $ Middle );
$ IpData1 = fread ($ fd, 4 );
If (strlen ($ ipData1) <4 ){
Fclose ($ fd );
Return 'system error ';
}
// The extracted data is converted into an integer. if the data is negative, the power of 2 is added.
$ Ip1num = implode (", unpack ('L', $ ipData1 ));
If ($ ip1num <0) $ ip1num + = pow (2, 32 );
// If the number of extracted long integers is greater than our IP address, modify the end position for the next loop.
If ($ ip1num> $ ipNum ){
$ EndNum = $ Middle;
Continue;
}
// Obtain the next index after obtaining the previous index
$ DataSeek = fread ($ fd, 3 );
If (strlen ($ DataSeek) <3 ){
Fclose ($ fd );
Return 'system error ';
}
$ DataSeek = implode (", unpack ('L', $ DataSeek. chr (0 )));
Fseek ($ fd, $ DataSeek );
$ IpData2 = fread ($ fd, 4 );
If (strlen ($ ipData2) <4 ){
Fclose ($ fd );
Return 'system error ';
}
$ Ip2num = implode (", unpack ('L', $ ipData2 ));
If ($ ip2num <0) $ ip2num + = pow (2, 32 );
// Unknown prompt not found
If ($ ip2num <$ ipNum ){
If ($ Middle = $ BeginNum ){
Fclose ($ fd );
Return 'unknown ';
}
$ BeginNum = $ Middle;
}
}
// The following code is dizzy. if you do not understand it, read it slowly.
$ IpFlag = fread ($ fd, 1 );
If ($ ipFlag = chr (1 )){
$ IpSeek = fread ($ fd, 3 );
If (strlen ($ ipSeek) <3 ){
Fclose ($ fd );
Return 'system error ';
}
$ IpSeek = implode (", unpack ('L', $ ipSeek. chr (0 )));
Fseek ($ fd, $ ipSeek );
$ IpFlag = fread ($ fd, 1 );
}
If ($ ipFlag = chr (2 )){
$ AddrSeek = fread ($ fd, 3 );
If (strlen ($ AddrSeek) <3 ){
Fclose ($ fd );
Return 'system error ';
}
$ IpFlag = fread ($ fd, 1 );
If ($ ipFlag = chr (2 )){
$ AddrSeek2 = fread ($ fd, 3 );
If (strlen ($ AddrSeek2) <3 ){
Fclose ($ fd );
Return 'system error ';
}
$ AddrSeek2 = implode (", unpack ('L', $ AddrSeek2.chr (0 )));
Fseek ($ fd, $ AddrSeek2 );
} Else {
Fseek ($ fd,-1, SEEK_CUR );
}
While ($ char = fread ($ fd, 1 ))! = Chr (0 ))
$ IpAddr2. = $ char;
$ AddrSeek = implode (", unpack ('L', $ AddrSeek. chr (0 )));
Fseek ($ fd, $ AddrSeek );
While ($ char = fread ($ fd, 1 ))! = Chr (0 ))
$ IpAddr1. = $ char;
} Else {
Fseek ($ fd,-1, SEEK_CUR );
While ($ char = fread ($ fd, 1 ))! = Chr (0 ))
$ IpAddr1. = $ char;
$ IpFlag = fread ($ fd, 1 );
If ($ ipFlag = chr (2 )){
$ AddrSeek2 = fread ($ fd, 3 );
If (strlen ($ AddrSeek2) <3 ){
Fclose ($ fd );
Return 'system error ';
}
$ AddrSeek2 = implode (", unpack ('L', $ AddrSeek2.chr (0 )));
Fseek ($ fd, $ AddrSeek2 );
} Else {
Fseek ($ fd,-1, SEEK_CUR );
}
While ($ char = fread ($ fd, 1 ))! = Chr (0 )){
$ IpAddr2. = $ char;
}
}
Fclose ($ fd );
// Return the result after the replacement operation is completed.
If (preg_match ('/http/I', $ ipAddr2 )){
$ IpAddr2 = ";
}
$ Ipaddr = "$ ipAddr1 $ ipAddr2 ″;
$ Ipaddr = preg_replace ('/CZ88.Net/is', ", $ ipaddr );
$ Ipaddr = preg_replace ('/^ s */is', ", $ ipaddr );
$ Ipaddr = preg_replace ('/s * $/is', ", $ ipaddr );
If (preg_match ('/http/I', $ ipaddr) | $ ipaddr = "){
$ Ipaddr = 'unknown ';
}
Return $ ipaddr;
}
?>

Javascript code: