base_url and port number

how can i construct the following URL for my site?

http://127.0.0.1:8080/appname/

calls to base_url() return this http://127.0.0.1/appname/

how can i construct the following URL for my site?

http://127.0.0.1:8080/appname/

calls to base_url() return this http://127.0.0.1/appname/

Set in application/config/config.php:

PHP Code:

$config['base_url'] = 'http://127.0.0.1:8080/appname/'; 


But the problem is, that I'm deploying to a server and I don't know what the server address or base URL will be.

The address can automatically change from  http://127.0.0.1:8080/appname/ to http://127.0.0.2:8081/appname/

So, I can't hard code the:

PHP Code:

$config['base_url'] = 'http://127.0.0.1:8080/appname/'; 


Can CI determine the base URL without me setting that config value?

This code is from CI manual, with some changes

PHP Code:

// change your domain below
$allowed_domains = array('domain1.tld', 'domain2.tld');
$default_domain  = 'domain1.tld';

if (in_array($_SERVER['HTTP_HOST'], $allowed_domains, TRUE))
{
        $domain = $_SERVER['HTTP_HOST'];
}
else
{
        $domain = $default_domain;
}

// get server port
$port = $_SERVER['SERVER_PORT'];

if ( ! empty($_SERVER['HTTPS']))
{
        $config['base_url'] = 'https://'.$domain.':'.$port.'/appname/';
}
else
{
        $config['base_url'] = 'http://'.$domain.':'.$port.'/appname/';
}