如何使用PHP-Parser获取全局变量名并修改

Question

我想在我想检查节点名称是否等于 (_POST, _GET, _REQUEST) 的地方使用 PHP-Parser library to get the global method (_POST, _GET, _REQUEST) to get values in PHP. I'm using PHP-Parser。我仍然是 PHP-Parser 的初学者，不知道如何获取这些全局变量。例如，如果我有以下源代码：

代码：

<?php 
$firstname = $_POST['firstname];

我目前使用的 PHP-parser 如下所示：

<?php

require_once('vendor/autoload.php');
use PhpParser\Error;
use PhpParser\NodeDumper;
use PhpParser\ParserFactory;


$code = <<<'CODE'
<?php
$firstname=  $_POST['firstname'];
CODE;


$parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
try {
    $ast = $parser->parse($code);
} catch (Error $error) {
    echo "Parse error: {$error->getMessage()}\n";
    return;
}


use PhpParser\{Node, NodeTraverser, NodeVisitorAbstract};



$traverser = new NodeTraverser;


// This code exist in the PHP-Parser documentation
$traverser->addVisitor(new class extends NodeVisitorAbstract {
    public function leaveNode(Node $node) {
    if ($node instanceof Node\Stmt\Expression
        && $node->expr instanceof Node\Expr\FuncCall
        && $node->expr->name instanceof Node\Name
        && $node->expr->name->toString() === '_POST'
    ) {
        // Change the $_POST['firstname'] and replace it with XXX value 
    }
}

});


print_r($modifiedStmts = $traverser->traverse($ast) );

执行上面的 PHP-Parser AST 后，我得到以下结果：

Array ( [0] => PhpParser\Node\Stmt\Expression Object ( [expr] => PhpParser\Node\Expr\Assign Object ( [var] => PhpParser\Node\Expr\Variable Object ( [name] => firstname [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 ) ) [expr] => PhpParser\Node\Expr\ArrayDimFetch Object ( [var] => PhpParser\Node\Expr\Variable Object ( [name] => _POST [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 ) ) [dim] => PhpParser\Node\Scalar\String_ Object ( [value] => firstname [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 [kind] => 1 ) ) [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 ) ) [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 ) ) [attributes:protected] => Array ( [startLine] => 2 [endLine] => 2 ) ) )

如何检测测试代码是否有_POST, _GET, REQUEST？例如：

// Something like this
if($node->value === '_POST' OR $node->value === '_GET' or $node->value === '_REQUEST') 
{
     // Do next step to change the global variable to specific text value
}

如何将 $_POST[firstname] 更改为 hello world! or any text 值？例如：

$firstname = $_POST['firstname'];

之后

$firstname = "hello World!";

感谢您的帮助

Answer 1

这应该适用于您突出显示的特定实例，它只适用于 POST 实例，但应该很容易扩展。

主要部分是当您看到代码的 AST 时，请尝试确保您可以识别 _POST 访问的基础。这原来是一个Node\Expr\ArrayDimFetch，然后在这个里面你想检查它使用的变量是否是_POST。

一旦你确定了这一点，你就可以用一个新的节点替换那个节点，它只是一个字符串 Node\Scalar\String_("Hello World!");.

$traverser->addVisitor(new class extends NodeVisitorAbstract {
    public function leaveNode(Node $node) {
        if ($node instanceof Node\Expr\ArrayDimFetch
            && $node->var instanceof Node\Expr\Variable
            && $node->var->name === '_POST'
            ) {
                // Change the $_POST['firstname'] and replace it with XXX value
                return new Node\Scalar\String_("Hello World!");
            }
    }

});

$prettyPrinter = new PhpParser\PrettyPrinter\Standard;
echo $prettyPrinter->prettyPrintFile($traverser->traverse($ast));

来自你的原始代码

<?php
$firstname=  $_POST['firstname'];

此代码输出....

<?php

$firstname = 'Hello World!';

如何使用PHP-Parser获取全局变量名并修改

How to use PHP-Parser to get the global variables name and change it

php

abstract-syntax-tree

php-parser