php中获取真实IP地址与IP地址验证函数

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;
}

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;
}