Sanitize filters

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**List of filters for sanitization**
ID	Name	Flags	Description
`FILTER_SANITIZE_EMAIL`	"email"		Remove all characters except letters, digits and !#$%&'+-=?^_`{\|}~@.[]*.
`FILTER_SANITIZE_ENCODED`	"encoded"	`FILTER_FLAG_STRIP_LOW` , `FILTER_FLAG_STRIP_HIGH` , `FILTER_FLAG_ENCODE_LOW` , `FILTER_FLAG_ENCODE_HIGH`	URL-encode string, optionally strip or encode special characters.
`FILTER_SANITIZE_MAGIC_QUOTES`	"magic_quotes"		Apply addslashes() .
`FILTER_SANITIZE_NUMBER_FLOAT`	"number_float"	`FILTER_FLAG_ALLOW_FRACTION` , `FILTER_FLAG_ALLOW_THOUSAND` , `FILTER_FLAG_ALLOW_SCIENTIFIC`	Remove all characters except digits, +- and optionally .,eE.
`FILTER_SANITIZE_NUMBER_INT`	"number_int"		Remove all characters except digits, plus and minus sign.
`FILTER_SANITIZE_SPECIAL_CHARS`	"special_chars"	`FILTER_FLAG_STRIP_LOW` , `FILTER_FLAG_STRIP_HIGH` , `FILTER_FLAG_ENCODE_HIGH`	HTML-escape '"<>& and characters with ASCII value less than 32, optionally strip or encode other special characters.
`FILTER_SANITIZE_FULL_SPECIAL_CHARS`	"full_special_chars"	`FILTER_FLAG_NO_ENCODE_QUOTES` ,	Equivalent to calling htmlspecialchars() with `ENT_QUOTES` set. Encoding quotes can be disabled by setting `FILTER_FLAG_NO_ENCODE_QUOTES` . Like htmlspecialchars() , this filter is aware of the default_charset and if a sequence of bytes is detected that makes up an invalid character in the current character set then the entire string is rejected resulting in a 0-length string. When using this filter as a default filter, see the warning below about setting the default flags to 0.
`FILTER_SANITIZE_STRING`	"string"	`FILTER_FLAG_NO_ENCODE_QUOTES` , `FILTER_FLAG_STRIP_LOW` , `FILTER_FLAG_STRIP_HIGH` , `FILTER_FLAG_ENCODE_LOW` , `FILTER_FLAG_ENCODE_HIGH` , `FILTER_FLAG_ENCODE_AMP`	Strip tags, optionally strip or encode special characters.
`FILTER_SANITIZE_STRIPPED`	"stripped"		Alias of "string" filter.
`FILTER_SANITIZE_URL`	"url"		Remove all characters except letters, digits and $-_.+!'(),{}\|\\^~[]`<>#%";/?:@&=*.
`FILTER_UNSAFE_RAW`	"unsafe_raw"	`FILTER_FLAG_STRIP_LOW` , `FILTER_FLAG_STRIP_HIGH` , `FILTER_FLAG_ENCODE_LOW` , `FILTER_FLAG_ENCODE_HIGH` , `FILTER_FLAG_ENCODE_AMP`	Do nothing, optionally strip or encode special characters. This filter is also aliased to `FILTER_DEFAULT` .

Warning

When using one of these filters as a default filter either through your ini file or through your web server's configuration, the default flags is set to FILTER_FLAG_NO_ENCODE_QUOTES . You need to explicitly set filter.default_flags to 0 to have quotes encoded by default. Like this:

Example #1 Configuring the default filter to act like htmlspecialchars

 
filter.default = full_special_chars
filter.default_flags = 0

更新日志

版本	说明
5.2.11/5.3.1	Slashes (/) are removed by `FILTER_SANITIZE_EMAIL` . Prior they were retained.

用户评论:

[#1] Anonymous [2015-10-22 15:56:04]

FILTER_SANITIZE_STRING doesn't behavior the same as strip_tags function. strip_tags allows less than symbol inferred from context, FILTER_SANITIZE_STRING strips regardless.
<?php $smaller = "not a tag < 5"; echo strip_tags($smaller); // -> not a tag < 5 echo filter_var ( $smaller, FILTER_SANITIZE_STRING); // -> not a tag ?>

[#2] david dot drakulovski at gmail dot com [2014-02-25 19:54:45]

Here is a simpler and a better presented ASCII list for the <32 or 127> filters
(if wikipedia confused the hell out of you):

http://www.danshort.com/ASCIImap/

[#3] galvao at galvao dot eti dot br [2013-03-02 06:04:16]

Just to clarify, since this may be unknown for a lot of people:

ASCII characters above 127 are known as "Extended" and they represent characters such as greek letters and accented letters in latin alphabets, used in languages such as pt_BR.

A good ASCII quick reference (aside from the already mentioned Wikipedia article) can be found at: http://www.asciicodes.com/

[#4] Anonymous [2013-02-15 19:42:42]

Support for FILTER_SANITIZE_FULL_SPECIAL_CHARS was added from version 5.3.3

[#5] googlybash24 at aol dot com [2012-09-19 17:39:00]

Remember to trim() the $_POST before your filters are applied:

<?php // We trim the $_POST data before any spaces get encoded to "%20" // Trim array values using this function "trim_value" function trim_value(&$value) { $value = trim($value); // this removes whitespace and related characters from the beginning and end of the string } array_filter($_POST, 'trim_value'); // the data in $_POST is trimmed $postfilter = // set up the filters to be used with the trimmed post array array( 'user_tasks' => array('filter' => FILTER_SANITIZE_STRING, 'flags' => !FILTER_FLAG_STRIP_LOW), // removes tags. formatting code is encoded -- add nl2br() when displaying 'username' => array('filter' => FILTER_SANITIZE_ENCODED, 'flags' => FILTER_FLAG_STRIP_LOW), // we are using this in the url 'mod_title' => array('filter' => FILTER_SANITIZE_ENCODED, 'flags' => FILTER_FLAG_STRIP_LOW), // we are using this in the url ); $revised_post_array = filter_var_array($_POST, $postfilter); // must be referenced via a variable which is now an array that takes the place of $_POST[] echo (nl2br($revised_post_array['user_tasks'])); //-- use nl2br() upon output like so, for the ['user_tasks'] array value so that the newlines are formatted, since this is our HTML <textarea> field and we want to maintain newlines ?>

[#6] googlybash24 at aol dot com [2012-09-13 08:39:01]

This should help with most simple "textarea" fields in post forms.

Removing user html tags while maintaining text formatting such as newlines and carriage returns involves using the FILTER_SANITIZE_STRING filter ID with the flag !FILTER_FLAG_STRIP_LOW. The formatting text (the low ASCII values under decimal 32) are encoded because of the included FILTER_FLAG_ENCODE_LOW flag, but you are now preventing these from being removed. When you want to display the value on the page back in its intended format, use nl2br() so the encoded newlines are formatted properly on the page.

This example cleans $_POST data from a textarea field with the name "user_tasks" on a previous html form, stripping tags but maintaining formatting (at least for newlines):

<?php $postfilter = array( 'user_tasks' => array('filter' => FILTER_SANITIZE_STRING, 'flags' => !FILTER_FLAG_STRIP_LOW), // removes tags. formatting code is encoded -- add nl2br() when displaying ); $revised_post_array = filter_input_array(INPUT_POST, $postfilter); // must be referenced via a variable which is now an array that takes the place of $_POST[] echo (nl2br($revised_post_array['user_tasks'])); // here we use nl2br() for the displayed value, for the ['user_tasks'] array value so that the newlines are formatted ?>

[#7] adellemfrank at hotmail dot com [2012-07-09 19:07:59]

A good list of which ASCII characters are < 32 and > 127 can be found at: http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters

[#8] scamber256 at hotmail dot de [2011-08-06 14:37:04]

Just a hint I tested,

You can obtain all the chars <32 (so newline and c.return), by using not operator > !FILTER_FLAG_STRIP_LOW as the last argument.

Example:
filter_input(INPUT_GET,'test',FILTER_SANITIZE_STRING,!FILTER_FLAG_STRIP_LOW);

The filter keeps working as before removing anything else as before apart from FILTER_FLAG_STRIP_LOW.
Just filter those "bad" chars <32 manually you don't want.

[#9] Dmitry Snytkine [2011-04-11 04:17:10]

Beware that FILTER_FLAG_STRIP_LOW strips NEWLINE and TAG and CARRIAGE RETURN chars. If you have a form that accepts user input in plaintext format, all the submitted text will lose all the line breaks, making it appear all on one line. This basically renders this filter useless for parsing user-submitted text, even in plain text.

[#10] marcus at synchromedia dot co dot uk [2009-11-27 01:07:04]

It's not entirely clear what the LOW and HIGH ranges are. LOW is characters below 32, HIGH is those above 127, i.e. outside the ASCII range.

<?php $a = "\tcaf??\n"; //This will remove the tab and the line break echo filter_var($a, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW); //This will remove the ??. echo filter_var($a, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_HIGH); ?>