Get the real IP address and IP address verification function in php

This article introduces two functions. One is to verify the IP address, and the other is to obtain the user's real IP address. They are also two commonly used IP operation functions. Students in need can refer to them.

1. Obtain the user’s real IP address

function get_client_ip( ) 
{ 
        if ( getenv( "REMOTE_ADDR" ) && strcasecmp( getenv( "REMOTE_ADDR" ), "unknown" ) ) 
        { 
                $onlineip = getenv( "REMOTE_ADDR" ); 
                return $onlineip; 
        } 
        if ( isset( $_SERVER['REMOTE_ADDR'] ) && $_SERVER['REMOTE_ADDR'] && strcasecmp( $_SERVER['REMOTE_ADDR'], "unknown" ) ) 
        { 
                $onlineip = $_SERVER['REMOTE_ADDR']; 
                return $onlineip; 
        } 
        if ( getenv( "HTTP_CLIENT_IP" ) && strcasecmp( getenv( "HTTP_CLIENT_IP" ), "unknown" ) ) 
        { 
                $onlineip = getenv( "HTTP_CLIENT_IP" ); 
                return $onlineip; 
        } 
        if ( getenv( "HTTP_X_FORWARDED_FOR" ) && strcasecmp( getenv( "HTTP_X_FORWARDED_FOR" ), "unknown" ) ) 
        { 
                $onlineip = getenv( "HTTP_X_FORWARDED_FOR" ); 
        } 
        return $onlineip; 
}

Determine whether it is an IP address

function is_ip( $IP ) 
{ 
        $IP_ARRAY = explode( ".", $IP ); 
        $IP_ARRAY_NUM = sizeof( $IP_ARRAY ); 
        if ( $IP_ARRAY_NUM != 4 ) 
        { 
                return FALSE; 
        } 
        $I = 0; 
        for ( ;    $I < $IP_ARRAY_NUM;    ++$I    ) 
        { 
                if ( !is_numeric( $IP_ARRAY[$I] ) && $IP_ARRAY[$I] < 0 || 255 < $IP_ARRAY[$I] ) 
                { 
                        return FALSE; 
                } 
                if ( !( $I == 3 ) && !( $IP_ARRAY[$I] == 255 ) ) 
                { 
                        continue; 
                } 
                return FALSE; 
        } 
        return TRUE; 
}

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