PHP 5.6.0beta1 released

Filtros de saneamiento

Lista de filtros de saneamiento
ID Nombre Opciones Banderas Descripción
FILTER_SANITIZE_EMAIL "email"     Elimina todos los caracteres menos letras, dígitos y !#$%&'*+-/=?^_`{|}~@.[].
FILTER_SANITIZE_ENCODED "encoded"   FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_LOW, FILTER_FLAG_ENCODE_HIGH String URL-encode, opcionalmente elimina o codifica caracteres especiales.
FILTER_SANITIZE_MAGIC_QUOTES "magic_quotes"     Aplica addslashes().
FILTER_SANITIZE_NUMBER_FLOAT "number_float"   FILTER_FLAG_ALLOW_FRACTION, FILTER_FLAG_ALLOW_THOUSAND, FILTER_FLAG_ALLOW_SCIENTIFIC Elimina todos los caracteres a excepción de los dígitos, +- y, opcionalmente, .,eE.
FILTER_SANITIZE_NUMBER_INT "number_int"     Elimina todos los caracteres excepto dígitos y los signos de suma y resta.
FILTER_SANITIZE_SPECIAL_CHARS "special_chars"   FILTER_FLAG_STRIP_LOW, FILTER_FLAG_STRIP_HIGH, FILTER_FLAG_ENCODE_HIGH Escapa caracteres HTML '"<>& y caracteres con valores ASCII menores que 32, opcionalmente elimina o codifica caracteres especiales.
FILTER_SANITIZE_FULL_SPECIAL_CHARS "full_special_chars"   FILTER_FLAG_NO_ENCODE_QUOTES, Equivalente a llamar a htmlspecialchars() con ENT_QUOTES establecido. Las comillas de codificación pueden ser desactivadas mediante el establecimiento de FILTER_FLAG_NO_ENCODE_QUOTES. Al igual que htmlspecialchars(), este filtro tiene en cuenta el default_charset y si en una secuencia de bytes se detecta que contiene un carácter no válido en el conjunto de caracteres actual entonces el string completo es rechazado lo que resulta en un string de longitud 0. Cuando se utiliza este filtro como un filtro predeterminado, vea la advertiencia de abajo sobre establecer las banderas predeterminadas a 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 Elimina etiquetas, opcionalmente elimina o codifica caracteres especiales.
FILTER_SANITIZE_STRIPPED "stripped"     Alias del filtro "string".
FILTER_SANITIZE_URL "url"     Elimina todos los caracteres excepto letras, dígitos y $-_.+!*'(),{}|\\^~[]`<>#%";/?:@&=.
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 No hace nada, opcionalmente elimina o codifica caracteres especiales.

Advertencia

Cuando se utiliza uno de estos tres filtros como un filtro predetermindo a través de fichero ini o de la configuración del servidor web, las banderas predeterminadas son establecidas a FILTER_FLAG_NO_ENCODE_QUOTES. Se necesita establecer explícitamente filter.default_flags a 0 para tener la codificación de comillas por omisión. Como esto:

Ejemplo #1 Configurar el filtro predeterminado para que actúe como htmlspecialchars

filter.default = full_special_chars
filter.default_flags = 0

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User Contributed Notes 9 notes

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9
adellemfrank at hotmail dot com
1 year ago
A good list of which ASCII characters are < 32 and > 127 can be found at: http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters
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5
googlybash24 at aol dot com
1 year ago
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
?>
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3
marcus at synchromedia dot co dot uk
4 years ago
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
$a
= "\tcafé\n";
//This will remove the tab and the line break
echo filter_var($a, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW);
//This will remove the é.
echo filter_var($a, FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_HIGH);
?>
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1
galvao at galvao dot eti dot br
1 year ago
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/
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1
david dot drakulovski at gmail dot com
1 month ago
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/
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-3
googlybash24 at aol dot com
1 year ago
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
?>
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-4
Anonymous
1 year ago
Support for FILTER_SANITIZE_FULL_SPECIAL_CHARS was added from version 5.3.3
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-4
scamber256 at hotmail dot de
2 years ago
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.
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-4
Dmitry Snytkine
3 years ago
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.
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