What are the security enhancements to the new features of PHP functions?

PHP 8’s new function features enhance security, including: 1. Parameter type checking: specify parameter types in the function signature to prevent type conversion errors and vulnerabilities; 2. Return value type hints: specify the return value type, forcing Enforce correct return value types and prevent errors; 3. Read-only attributes: Create attributes that can only be set during object initialization to prevent accidental modification of attributes and reduce security risks. By using type hints, security vulnerabilities such as code injection attacks can be detected and prevented.

Security enhancement measures for new features of PHP functions

PHP 8 introduces some new features aimed at enhancing function security . These features include:

Parameter type checking

PHP 8 allows type hints to be applied to parameters in function signatures. This helps ensure that the parameters passed to the function are of the correct type, preventing type conversion errors and potential security holes.

function sum(int $a, int $b): int
{
    return $a + $b;
}

// 类型错误，将引发 TypeError 异常
sum("1", "2");

Return value type hints

Similar to parameter type hints, PHP 8 also allows the return value type to be specified in the function signature. This helps enforce correct return value types and prevent bugs in your code.

function get_name(): string
{
    return "John Doe";
}

// 类型错误，将引发 TypeError 异常
$name = get_name();  // 预期为字符串，但实际上为整数

Read-only properties

PHP 8 introduced read-only properties, allowing the creation of properties that can only be set when the object is initialized. This helps prevent accidental modification of properties at runtime and reduces security risks.

class User
{
    private readonly string $username;

    public function __construct(string $username)
    {
        $this->username = $username;
    }
}

$user = new User("admin");

// 尝试修改只读属性，将引发 TypeError 异常
$user->username = "new_admin";

Practical Case

The following is a practical case showing how type hints can help detect and prevent security vulnerabilities:

function sanitize_input(string $input): string
{
    // 使用正则表达式过滤输入中的恶意脚本
    $pattern = '/<script>.*<\/script>/';
    $input = preg_replace($pattern, '', $input);

    return $input;
}

// 使用类型提示确保传递给函数的输入为字符串，从而防止代码注入攻击
$sanitized_input = sanitize_input("Hello, world!");

echo $sanitized_input;  // 输出："Hello, world!"

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