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Hostname

Zend_Validate_Hostname allows you to validate a hostname against a set of known specifications. It is possible to check for three different types of hostnames: a DNS Hostname (i.e. domain.com), IP address (i.e. 1.2.3.4), and Local hostnames (i.e. localhost). By default only DNS hostnames are matched.

Supported options for Zend_Validate_Hostname

The following options are supported for Zend_Validate_Hostname:

  • allow: Defines the sort of hostname which is allowed to be used. See Hostname types for details.

  • idn: Defines if IDN domains are allowed or not. This option defaults to TRUE.

  • ip: Allows to define a own IP validator. This option defaults to a new instance of Zend_Validate_Ip.

  • tld: Defines if TLDs are validated. This option defaults to TRUE.

Basic usage

A basic example of usage is below:

<?php
$validator 
= new Zend_Validate_Hostname();
if (
$validator->isValid($hostname)) {
    
// hostname appears to be valid
} else {
    
// hostname is invalid; print the reasons
    
foreach ($validator->getMessages() as $message) {
        echo 
"$message\n";
    }
}

This will match the hostname $hostname and on failure populate getMessages() with useful error messages.

Validating different types of hostnames

You may find you also want to match IP addresses, Local hostnames, or a combination of all allowed types. This can be done by passing a parameter to Zend_Validate_Hostname when you instantiate it. The parameter should be an integer which determines what types of hostnames are allowed. You are encouraged to use the Zend_Validate_Hostname constants to do this.

The Zend_Validate_Hostname constants are: ALLOW_DNS to allow only DNS hostnames, ALLOW_IP to allow IP addresses, ALLOW_LOCAL to allow local network names, ALLOW_URI to allow RFC3986-compliant addresses, and ALLOW_ALL to allow all four above types.

Additional Information on ALLOW_URI

ALLOW_URI allows to check hostnames according to RFC3986. These are registered names which are used by WINS, NetInfo and also local hostnames like those defined within your .hosts file.

To just check for IP addresses you can use the example below:

<?php
$validator 
= new Zend_Validate_Hostname(Zend_Validate_Hostname::ALLOW_IP);
if (
$validator->isValid($hostname)) {
    
// hostname appears to be valid
} else {
    
// hostname is invalid; print the reasons
    
foreach ($validator->getMessages() as $message) {
        echo 
"$message\n";
    }
}

As well as using ALLOW_ALL to accept all common hostnames types you can combine these types to allow for combinations. For example, to accept DNS and Local hostnames instantiate your Zend_Validate_Hostname object as so:

<?php
$validator 
= new Zend_Validate_Hostname(Zend_Validate_Hostname::ALLOW_DNS |
                                        
Zend_Validate_Hostname::ALLOW_IP);

Validating International Domains Names

Some Country Code Top Level Domains (ccTLDs), such as 'de' (Germany), support international characters in domain names. These are known as International Domain Names (IDN). These domains can be matched by Zend_Validate_Hostname via extended characters that are used in the validation process.

IDN domains

Until now more than 50 ccTLDs support IDN domains.

To match an IDN domain it's as simple as just using the standard Hostname validator since IDN matching is enabled by default. If you wish to disable IDN validation this can be done by either passing a parameter to the Zend_Validate_Hostname constructor or via the setValidateIdn() method.

You can disable IDN validation by passing a second parameter to the Zend_Validate_Hostname constructor in the following way.

<?php
$validator 
=
    new 
Zend_Validate_Hostname(
        array(
            
'allow' => Zend_Validate_Hostname::ALLOW_DNS,
            
'idn'   => false
        
)
    );

Alternatively you can either pass TRUE or FALSE to setValidateIdn() to enable or disable IDN validation. If you are trying to match an IDN hostname which isn't currently supported it is likely it will fail validation if it has any international characters in it. Where a ccTLD file doesn't exist in Zend/Validate/Hostname specifying the additional characters a normal hostname validation is performed.

IDN validation

Please note that IDNs are only validated if you allow DNS hostnames to be validated.

Validating Top Level Domains

By default a hostname will be checked against a list of known TLDs. If this functionality is not required it can be disabled in much the same way as disabling IDN support. You can disable TLD validation by passing a third parameter to the Zend_Validate_Hostname constructor. In the example below we are supporting IDN validation via the second parameter.

<?php
$validator 
=
    new 
Zend_Validate_Hostname(
        array(
            
'allow' => Zend_Validate_Hostname::ALLOW_DNS,
            
'idn'   => true,
            
'tld'   => false
        
)
    );

Alternatively you can either pass TRUE or FALSE to setValidateTld() to enable or disable TLD validation.

TLD validation

Please note TLDs are only validated if you allow DNS hostnames to be validated.

Zend Framework