php - 如果已经使用 FILTER_VALIDATE_EMAIL，FILTER_SANITIZE_EMAIL 是否毫无意义？

Question

我只是在创建一个注册表单，我只想将有效且安全的电子邮件插入数据库。

一些网站(包括 w3schools)建议在运行 FILTER_VALIDATE_EMAIL 之前运行 FILTER_SANITIZE_EMAIL 以确保安全；但是，这可能会将提交的电子邮件从无效的电子邮件更改为有效的电子邮件，这可能不是用户想要的，例如:

用户有电子邮件地址 jeff!@gmail.com，但不小心插入了 jeff"@gmail.com。

FILTER_SANITIZE_EMAIL 将删除 "使 FILTER_VALIDATE_EMAIL 所说的电子邮件 jeff@gmail.com 有效，即使它不是用户的实际电子邮件地址。

为了避免这个问题，我打算只运行 FILTER_VALIDATE_EMAIL。 (假设我不打算输出/处理任何声明无效的电子邮件)

这将告诉我电子邮件是否有效。如果是这样，则不需要通过 FILTER_SANITIZE_EMAIL 传递它，因为任何非法/不安全字符，都会导调用子邮件无效返回，对吗？

我也不知道有任何被 FILTER_VALIDATE_EMAIL 批准为有效的电子邮件可用于注入(inject)/xss，因为空格、括号 () 和分号会使电子邮件无效。还是我错了？

(注意:除此之外，我将使用准备好的语句插入数据，我只是想澄清一下)

Answer 1

以下是仅插入有效电子邮件的方法。

<?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 和 FILTER_SANITIZE_EMAIL 都是有值(value)的函数，并且有不同的用途。

验证正在测试电子邮件格式是否有效。清理是清除电子邮件中的不良字符。

<?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，所以这些问题只要使用它就可以轻松回答。

Source for FILTER_SANITIZE_EMAIL :

/* {{{ 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);
}    

Source for FILTER_VALIDATE_EMAIL :

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
}

}