search
HomeBackend DevelopmentPHP TutorialPHP中字符安全过滤函数使用小结_php技巧

在WEB开发过程中,我们经常要获取来自于世界各地的用户输入的数据。但是,我们“永远都不能相信那些用户输入的数据”。所以在各种的Web开发语言中,都会提供保证用户输入数据安全的函数。在PHP中,有些非常有用并且方便的函数,它们可以帮助你防止出现像SQL注入攻击,XSS攻击等问题。

1. mysql_real_escape_string()

这个函数曾经对于在PHP中防止SQL注入攻击提供了很大的帮助,它对特殊的字符,像单引号和双引号,加上了“反斜杠”,确保用户的输入在用它去查询之前已经是安全的了。但你要注意你是在连接着数据库的情况下使用这个函数。
但现在mysql_real_escape_string()这个函数基本不用了,所有新的应用开发都应该使用像PDO这样的库对数据库进行操作,也就是说,我们可以使用现成的语句防止SQL注入攻击。

2. addslashes()

这个函数和上面的mysql_real_escape_string()很相似,同样是为特殊字符加上反斜杠,但要注意当设置文件php.ini中的 magic_quotes_gpc 的值为“on”时,不要使用这个函数。magic_quotes_gpc = on时,对所有的 GET、POST 和 COOKIE 数据自动运行 addslashes()。不要对已经被 magic_quotes_gpc 转义过的字符串 使用 addslashes(),因为这样会导致双层转义。你可以通过PHP中get_magic_quotes_gpc()函数检查这个变量的值。

3. htmlentities()

这个函数对过滤用户输入数据非常有用,它可以把字符转换为 HTML 实体。比如,当用户输入字符“

4. htmlspecialchars()

这个函数跟上面的很相似,HTML中的一些字符有着特殊的含义,如果要体现这样的含义,就要被转换为HTML实体,这个函数会返回转换后的字符串。

5. strip_tags()

这个函数可以去除字符串中所有的HTML,JavaScript和PHP标签,当然你也可以通过设置该函数的第二个参数,忽略过滤一些特定的标签。

6. intval()

intval其实不属于过滤的函数,它的作用是将变量转成整数类型。在我们需要得到一个整数的参数时非常有用,你可以用这个函数让你的PHP代码更安全,特别是当你在解析id,年龄这样的整数形数据时。

这些都是PHP内置的字符串过滤函数,十分简单实用,希望小伙伴们能用好他们。

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
What are some common problems that can cause PHP sessions to fail?What are some common problems that can cause PHP sessions to fail?Apr 25, 2025 am 12:16 AM

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

How do you debug session-related issues in PHP?How do you debug session-related issues in PHP?Apr 25, 2025 am 12:12 AM

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

What happens if session_start() is called multiple times?What happens if session_start() is called multiple times?Apr 25, 2025 am 12:06 AM

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

How do you configure the session lifetime in PHP?How do you configure the session lifetime in PHP?Apr 25, 2025 am 12:05 AM

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

What are the advantages of using a database to store sessions?What are the advantages of using a database to store sessions?Apr 24, 2025 am 12:16 AM

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

How do you implement custom session handling in PHP?How do you implement custom session handling in PHP?Apr 24, 2025 am 12:16 AM

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

What is a session ID?What is a session ID?Apr 24, 2025 am 12:13 AM

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

How do you handle sessions in a stateless environment (e.g., API)?How do you handle sessions in a stateless environment (e.g., API)?Apr 24, 2025 am 12:12 AM

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software