PHP表单增加token验证，防止站外及重复提交

token用于常用的表单防止重复提交及站外提交的一个常用的处理方式了，下文我们一起来看一个PHP表单增加token验证，防止站外及重复提交例子。

原理在于生成一个随机字符串放在session里。提交表单后来验证这个字符串。可以做到防止他人自己写form来欺骗提交，重复提交或者双击提交。

Token.php

/*
* Created on 2013-3-25
*
* To change the template for this generated file go to
* Window - Preferences - PHPeclipse - PHP - Code Templates
*/
function getToken($len = 32, $md5 = true) {
# Seed random number generator
# Only needed for PHP versions prior to 4.2
mt_srand((double) microtime() * 1000000);
# Array of characters, adjust as desired
$chars = array (
'Q',
'@',
'8',
'y',
'%',
'^',
'5',
'Z',
'(',
'G',
'_',
'O',
'`',
'S',
'-',
'N',
' 'D',
'{',
'}',
'[',
']',
'h',
';',
'W',
'.',
'//m.sbmmt.com/m/',
'|',
':',
'1',
'E',
'L',
'4',
'&',
'6',
'7',
'//m.sbmmt.com/m/faq/#',
'9',
'a',
'A',
'b',
'B',
'~',
'C',
'd',
'>',
'e',
'2',
'f',
'P',
'g',
')',
'?',
'H',
'i',
'X',
'U',
'J',
'k',
'r',
'l',
'3',
't',
'M',
'n',
'=',
'o',
'+',
'p',
'F',
'q',
'!',
'K',
'R',
's',
'c',
'm',
'T',
'v',
'j',
'u',
'V',
'w',
',',
'x',
'I',
'$',
'Y',
'z',
'*'
);
# Array indice friendly number of chars;
$numChars = count($chars) - 1;
$token = '';
# Create random token at the specified length
for ($i = 0; $i $token .= $chars[mt_rand(0, $numChars)];
# Should token be run through md5?
if ($md5) {
# Number of 32 char chunks
$chunks = ceil(strlen($token) / 32);
$md5token = '';
# Run each chunk through md5
for ($i = 1; $i $md5token .= md5(substr($token, $i * 32 - 32, 32));
# Trim the token
$token = substr($md5token, 0, $len);
}
return $token;
}
?>

form.php

include_once("token.php");
$token = getToken();
session_start();
$_SESSION['token'] = $token;
?>

action.php

session_start();
if($_POST['token'] == $_SESSION['token']){
unset($_SESSION['token']);
echo "这是一个正常的提交请求";
}else{
echo "这是一个非法的提交请求";
}
?>