Check the domain name php
Returns true for «1», «true», «on» and «yes». Returns false otherwise.
If FILTER_NULL_ON_FAILURE is set, false is returned only for «0», «false», «off», «no», and «», and null is returned for all non-boolean values.
String values are trimmed using trim() before comparison.
Validates whether the domain name label lengths are valid.
Validates domain names against RFC 1034, RFC 1035, RFC 952, RFC 1123, RFC 2732, RFC 2181, and RFC 1123. Optional flag FILTER_FLAG_HOSTNAME adds ability to specifically validate hostnames (they must start with an alphanumeric character and contain only alphanumerics or hyphens).
Validates whether the value is a valid e-mail address.
In general, this validates e-mail addresses against the addr-spec syntax in » RFC 822, with the exceptions that comments and whitespace folding and dotless domain names are not supported.
Validates value as float, optionally from the specified range, and converts to float on success.
String values are trimmed using trim() before comparison.
Validates value as integer, optionally from the specified range, and converts to int on success.
String values are trimmed using trim() before comparison.
Note:
When default is set to option, default ‘s value is used if value is not validated.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | The FILTER_FLAG_SCHEME_REQUIRED and FILTER_FLAG_HOST_REQUIRED flags for the FILTER_VALIDATE_URL filter have been removed. The scheme and host are (and have been) always required. |
| 8.0.0 | Added FILTER_VALIDATE_BOOL as an alias for FILTER_VALIDATE_BOOLEAN . Using FILTER_VALIDATE_BOOL is preferred. |
| 7.4.0 | Added min_range and max_range options for FILTER_VALIDATE_FLOAT . |
| 7.0.0 | Added FILTER_FLAG_HOSTNAME and FILTER_VALIDATE_DOMAIN . |
User Contributed Notes 26 notes
FILTER_VALIDATE_URL does not work with URNs, examples of valid URIs according to RFC3986 and if they are accepted by FILTER_VALIDATE_URL:
since php 7.4
you can use these 3 beautiful conditions for from validation for validation less, great or in range
/**
* less_than_equal_to
*/
$x = 50 ;
if ( filter_var ( $x , FILTER_VALIDATE_FLOAT , [ «options» => [ «max_range» => 100 ]]) !== false ) echo «result : $x is less than OR equal to 100» ;
> else echo «result : $x is NOT less than OR equal to 100» ;
>
?>
result : 50 is less than OR equal to 100
/**
* greater_than_equal_to
*/
$x = 50 ;
if ( filter_var ( $x , FILTER_VALIDATE_FLOAT , [ «options» => [ «min_range» => 100 ]]) !== false ) echo «result : $x is greater than OR equal to 100» ;
> else echo «result : $x is NOT greater than OR equal to 100» ;
>
?>
result : 50 is NOT greater than OR equal to 100
/**
* less_than_equal_to && greater_than_equal_to
*/
$x = 50 ;
if ( filter_var ( $x , FILTER_VALIDATE_FLOAT , [ «options» => [ «min_range» => 0 , «max_range» => 100 ]]) !== false ) echo «result : $x is in range of 0 to 100» ;
> else echo «result : $x in NOT range of 0 to 100» ;
>
?>
result : 50 is in range of 0 to 100
Notably missing is a way to validate text entry as printable,
printable multiline,
or printable and safe (tag free)
FILTER_VALIDATE_TEXT, which validates no special characters
perhaps with FILTER_FLAG_ALLOW_NEWLINE
and FILTER_FLAG_NOTAG to disallow tag starters
Regarding «partial» addresses with no . in the domain part, a comment in the source code (in ext/filter/logical_filters.c) justifies this rejection thus:
* The regex below is based on a regex by Michael Rushton.
* However, it is not identical. I changed it to only consider routeable
* addresses as valid. Michael’s regex considers a@b a valid address
* which conflicts with section 2.3.5 of RFC 5321 which states that:
*
* Only resolvable, fully-qualified domain names (FQDNs) are permitted
* when domain names are used in SMTP. In other words, names that can
* be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed
* in Section 5) are permitted, as are CNAME RRs whose targets can be
* resolved, in turn, to MX or address RRs. Local nicknames or
* unqualified names MUST NOT be used.
FILTER_VALIDATE_EMAIL does NOT allow incomplete e-mail addresses to be validated as mentioned by Tomas.
$email = «clifton@example» ; //Note the .com missing
echo «PHP Version: » . phpversion (). ‘
‘ ;
if( filter_var ( $email , FILTER_VALIDATE_EMAIL )) <
echo $email . ‘
‘ ;
var_dump ( filter_var ( $email , FILTER_VALIDATE_EMAIL ));
>else <
var_dump ( filter_var ( $email , FILTER_VALIDATE_EMAIL ));
>
?>
Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
bool(false)
$email = «clifton@example.com» ; //Note the .com added
echo «PHP Version: » . phpversion (). ‘
‘ ;
if( filter_var ( $email , FILTER_VALIDATE_EMAIL )) <
echo $email . ‘
‘ ;
var_dump ( filter_var ( $email , FILTER_VALIDATE_EMAIL ));
>else <
var_dump ( filter_var ( $email , FILTER_VALIDATE_EMAIL ));
>
?>
Returns:
PHP Version: 5.2.14 //On MY server, may be different depending on which version you have installed.
clifton@example.com
string(16) «clifton@example.com»
This feature is only available for PHP Versions (PHP 5 >= 5.2.0) according to documentation. So make sure your version is correct.
Looks like FILTER_VALIDATE_DOMAIN isn’t available on PHP < 7:
It’s good to remember that using filter_var is primarily for filtering input values when doing boolean logic comparisons. Take the following:
$value = «12»;
if(filter_var($value, FILTER_VALIDATE_INT))
// validated as an int
>
The above works as intended, except when $value = «0». In which case filter_var returns a 0, aka false when used as a boolean.
For the correct behavior, do a zero check.
$value = » 0 «;
$filtered = filter_var($value, FILTER_VALIDATE_INT);
if($filtered || $filtered === 0)
// validated as an int
>
FILTER_FLAG_QUERY_REQUIRED is failing URLs that are encoded e.g.
So anything more than one word encoded fails.
The description for FILTER_VALIDATE_URL seems incorrect/misleading. «Beware a valid URL may not specify the HTTP protocol» implies a valid URL cannot specify the HTTP protocol. I think «Beware a valid URL need not specify. » would be better.
FILTER_VALIDATE_EMAIL not only doesn’t support whitespace folding and comments. It only checks Addr-spec part of email address. Otherwise it should mark such address as valid: ‘Test Example
Also address «test@localhost» should be valid. Which is mentioned in another note.
You can test it with this code:
$emails = array(
‘Test Example ‘ ,
‘test@localhost’ ,
‘test@localhost.com’
);
foreach ( $emails as $email ) echo ( filter_var ( $email , FILTER_VALIDATE_EMAIL )) ?
«[+] Email ‘ $email ‘ is valid\n» :
«[-] Email ‘ $email ‘ is NOT valid\n» ;
>
?>
Output for PHP 5.3.21 — 7.0.1 :
[-] Email ‘Test Example ‘ is NOT valid
[-] Email ‘test@localhost’ is NOT valid
[+] Email ‘test@localhost.com’ is valid
Note that if using FILTER_NULL_ON_FAILURE as a flag with the FILTER_VALIDATE_BOOLEAN id then NULL is no longer returned if the variable name is not set in the external variable array. It will instead return FALSE. In the description is says that when using the FILTER_NULL_ON_FAILURE flag that ‘ FALSE is returned only for «0», «false», «off», «no», and «»‘ an makes no mention of this additional state that can also return false. The behavior is mentioned on the filter_input documentation page under Return Values but that is not overly helpful if one is just looking here.
If FILTER_NULL_ON_FAILURE is not used then NULL is returned when the variable name is not set in the external variable array, TRUE is returned for «1», «true», «on» and «yes» and FALSE is returned for everything else.
FILTER_VALIDATE_EMAIL is discarding valid e-mail addresses containing IDN. Since there are real, live IDNs on the Internet, that means the filtered output is too strict, leading to false negatives.
Punycode-encoded IDN addresses pass the filter correctly; so before checking for validity, it is necessary to convert the e-mail address to punycode.
Rejection of so-called partial domains because of «missing» dot is not following section 2.3.5 of RFC 5321.
It says FQDNs are permitted, and com, org, or va are (well, may be) valids FQDNs. It depends on DNS, not on syntax.
Some TDLs (although few of them) have MX RRs, the for example «abuse@va» is correct.
Often I see some code like the following:
$value = «12»;
if( filter_var($value, FILTER_VALIDATE_INT) )
// validated as an int
>
The above works as intended, except when $value is «0». In the above case it will be interpreted as FALSE.
For the correct behavior, you have not only to check if it is equal (==) to false, but also identic (===) to FALSE:
$value = » 0 «;
if( filter_var($value, FILTER_VALIDATE_INT) === FALSE )
// validated as an int
>
FILTER_VALIDATE_URL do not support IDN in any form, i.e., neither rødgrød.dk nor xn--rdgrd-vuad.dk even though the domain is active.
FILTER_VALIDATE_INT first casts its value to string which produces unexpected result for bool and float (https://bugs.php.net/bug.php?id=72490):
// Prints int(1).
var_dump ( filter_var ( true , FILTER_VALIDATE_INT ));
// . but this prints bool(false).
var_dump ( filter_var ( false , FILTER_VALIDATE_INT ));
// Prints bool(false).
var_dump ( filter_var ( 1.1 , FILTER_VALIDATE_INT ));
// . but this prints int(0).
var_dump ( filter_var ( 0.0 , FILTER_VALIDATE_INT ));
// . but this again is bool(false).
var_dump ( filter_var ( ‘0.0’ , FILTER_VALIDATE_INT ));
// Also bool(false).
var_dump ( filter_var ( ‘-0.0’ , FILTER_VALIDATE_INT ));
The docs are not clear on how exactly this casting affects the result for certain input values.
Contrary to what documentation implies, the FILTER_NULL_ON_FAILURE seem to affect any validation filter, not just FILTER_VALIDATE_BOOLEAN. I’ve been using that since PHP 5.2, and as of PHP 5.6.8 it still works. I have no clue if it’s a blug or if it is as intended, in which case the documentation needs to be fixed.
When the flag is used on a validation filter other than FILTER_VALIDATE_BOOLEAN, as expected the filter will return NULL instead of FALSE upon failure. This is quite useful when filtering a POST form with filter_input_array(), where you don’t want to check what field is invalid and what field is missing. Just check if NULL is among the returned elements and you’re done.
$definition = array(
‘login’ => array(
‘filter’ => FILTER_VALIDATE_STRING ,
‘flags’ => FILTER_NULL_ON_FAILURE
),
‘pwd’ => FILTER_UNSAFE_RAW
);
$form_data = filter_input_array ( INPUT_POST , $definition );
if( in_array ( null , $form_data , true )) // invalid form
> else // valid form, let’s proceed
>
?>
Of course, if you want more precise error messages that approach won’t work. But it’s still good to know, i believe.
A word to the wise regarding floats.
$t = ‘312041.25 € instead of 896.70 €’;
echo filter_var ($t, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION);
will return
312041.25896.70
which is likely not what you were expecting. In 2007 someone suggested it’s not acceptable (see https://bugs.php.net/bug.php?id=40156&edit=2) but it was flagged «not a bug» because these kind of filters are only supposed to filter out illegal characters.
Of course if you were to use FILTER_VALIDATE_FLOAT it would just return that the input is not valid.
When validating floats, you must use the Identical/Not identical operators for proper validation of zeros:
This will not work as expected:
$x = 0 ;
if (! filter_var ( $x , FILTER_VALIDATE_FLOAT )) echo » $x is a valid float» ;
> else echo » $x is NOT a valid float» ;
>
?>
This will work as expected:
$x = 0 ;
if ( filter_var ( $x , FILTER_VALIDATE_FLOAT )!== false ) echo » $x is a valid float» ;
> else echo » $x is NOT a valid float» ;
>
?>
When validating a URL, as documented, the protocol is not validated. However, it is required to be present.
I don’t expect a protocol to be present. To validate expected input I have to add a «protocol» as a prefix, and return true or false, and further validate the input.
$r = filter_var(»this.doesnt.matter.so.why.is.it.required://’.$host, FILTER_VALIDATE_URL);
return ($r != » && $r !== false) ? true : false;
@2:
$value = » 0 «;
$filtered = filter_var($value, FILTER_VALIDATE_INT);
if($filtered || $filtered === 0)
// validated as an int
>
I think next code is better:
$value = «0»;
if(filter_var($value, FILTER_VALIDATE_INT) !== false)
.
Please note that the FILTER_FLAG_NO_PRIV_RANGE flag does not exclude IPv4 private addresses in the IPv6 namespace, such as ::ffff:169.254.169.254.
FILTER_VALIDATE_FLOAT Security Risk CVE-2021-21708 High Risk from
Warning from MITRE Corporation, Common Vulnerabilities and Exposures:
In PHP versions 7.4.x below 7.4.28, 8.0.x below 8.0.16, and 8.1.x below 8.1.3, when using filter functions with FILTER_VALIDATE_FLOAT filter and min/max limits, if the filter fails, there is a possibility to trigger use of allocated memory after free, which can result it crashes, and potentially in overwrite of other memory chunks and RCE. This issue affects: code that uses FILTER_VALIDATE_FLOAT with min/max limits.