如果已经在使用FILTER_VALIDATE_EMAIL，FILTER_SANITIZE_EMAIL毫无意义吗？

下面介绍了如何仅插入有效的电子邮件。

<?php
$original_email = 'jeff"@gmail.com';

$clean_email = filter_var($original_email,FILTER_SANITIZE_EMAIL);

if ($original_email == $clean_email && filter_var($original_email,FILTER_VALIDATE_EMAIL)){
   // now you know the original email was safe to insert.
   // insert into database code go here. 
}

FILTER_VALIDATE_EMAIL并且都是有价值的功能，并且具有不同的用途。FILTER_SANITIZE_EMAIL

验证是测试电子邮件是否为有效格式。消毒是为了清除电子邮件中的坏字符。

<?php
$email = "test@hostname.com"; 
$clean_email = "";

if (filter_var($email,FILTER_VALIDATE_EMAIL)){
    $clean_email =  filter_var($email,FILTER_SANITIZE_EMAIL);
} 

// another implementation by request. Which is the way I would suggest
// using the filters. Clean the content and then make sure it's valid 
// before you use it. 

$email = "test@hostname.com"; 
$clean_email = filter_var($email,FILTER_SANITIZE_EMAIL);

if (filter_var($clean_email,FILTER_VALIDATE_EMAIL)){
    // email is valid and ready for use
} else {
    // email is invalid and should be rejected
}

PHP是开源的，所以这些问题很容易通过使用它来回答。

FILTER_SANITIZE_EMAIL来源：

/* {{{ php_filter_email */
#define SAFE        "$-_.+"
#define EXTRA       "!*'(),"
#define NATIONAL    "{}|\\^~[]`"
#define PUNCTUATION "<>#%\""
#define RESERVED    ";/?:@&="

void php_filter_email(PHP_INPUT_FILTER_PARAM_DECL)
{
    /* Check section 6 of rfc 822 http://www.faqs.org/rfcs/rfc822.html */
    const unsigned char allowed_list[] = LOWALPHA HIALPHA DIGIT "!#$%&'*+-=?^_`{|}~@.[]";
    filter_map     map;

    filter_map_init(&map);
    filter_map_update(&map, 1, allowed_list);
    filter_map_apply(value, &map);
}    

FILTER_VALIDATE_EMAIL来源：

void php_filter_validate_email(PHP_INPUT_FILTER_PARAM_DECL) /* {{{ */
{
const char regexp[] = "/^(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){255,})(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){65,}@)(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22))(?:\\.(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-+[a-z0-9]+)*\\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-+[a-z0-9]+)*)|(?:\\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\\]))$/iD";

pcre       *re = NULL;
pcre_extra *pcre_extra = NULL;
int preg_options = 0;
int         ovector[150]; /* Needs to be a multiple of 3 */
int         matches;


/* The maximum length of an e-mail address is 320 octets, per RFC 2821. */
if (Z_STRLEN_P(value) > 320) {
    RETURN_VALIDATION_FAILED
}

re = pcre_get_compiled_regex((char *)regexp, &pcre_extra, &preg_options TSRMLS_CC);
if (!re) {
    RETURN_VALIDATION_FAILED
}
matches = pcre_exec(re, NULL, Z_STRVAL_P(value), Z_STRLEN_P(value), 0, 0, ovector, 3);

/* 0 means that the vector is too small to hold all the captured substring offsets */
if (matches < 0) {
    RETURN_VALIDATION_FAILED
}

}

我读了同一篇文章，并想到了同样的事情：简单地改变一个无效变量是不够的。我们需要实际告诉用户存在问题，而不仅仅是忽略它。我认为，解决方案是将原始版本与经过消毒的版本进行比较。即，要使用w3schools示例，只需添加：

$cleanfield = filter_var($field, FILTER_SANITIZE_EMAIL);

if ($cleanfield != $field){
    return FALSE;
}