PHP (Symfony)

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Presentation

Symfony is the well-known PHP framework. It is intended to ease the development of PHP applications.

Symfony provides many methods conventions to authenticate users (basic, ldap,…) and to load external user sources (ldap, database). The method presented here relies on the “remote_user” method. (in security firewall)

Configuration

Follow these step to protect your application using the “REMOTE_USER” HTTP header.

  1. Adapt the app/config/security.yml configuration file as below:
security:

    encoders:
        AppBundle\Security\User\HeaderUser: plaintext

    providers:
        header:
            id: AppBundle\Security\User\HeaderUserProvider

    firewalls:
        dev:
            pattern: ^/(_(profiler|wdt)|css|images|js)/
            security: false

        main:
            pattern: ^/
            remote_user:
                user: HTTP_REMOTE_USER
            provider: header
  • encoders : define a password hashing scheme (useless in our case, but the parameter is mandatory)
  • providers : define the user providers (even virtual)
  • remote_user : define the authentication method to “assume the user is already authenticated and get an http variable to know his username”
  • user : define the HTTP header containing the username
  • provider : references the previously defined provider owning the user data (in our scenario, a virtual)
  1. Define a “header user” class

Create the file src/AppBundle/Security/User/HeaderUser.php :

<?php

// src/Security/User/HeaderUser.php
namespace AppBundle\Security\User;

use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Security\Core\User\EquatableInterface;

class HeaderUser implements UserInterface, EquatableInterface
{
    private $username;
    private $password;
    private $salt;
    private $roles;

    public function __construct($username, $password, $salt, array $roles)
    {
        $this->username = $username;
        $this->password = $password;
        $this->salt = $salt;
        $this->roles = $roles;
    }

    public function getRoles()
    {
        return $this->roles;
    }

    public function getPassword()
    {
        return $this->password;
    }

    public function getSalt()
    {
        return $this->salt;
    }
    public function getUsername()
    {
        return $this->username;
    }

    public function eraseCredentials()
    {
    }

    public function isEqualTo(UserInterface $user)
    {
        if (!$user instanceof HeaderUser) {
            return false;
        }

        if ($this->username !== $user->getUsername()) {
            return false;
        }

        //if ($this->password !== $user->getPassword()) {
        //    return false;
        //}

        return true;
    }
}
?>
  1. Define a “header user provider” class relying on the previous class

Create the file src/AppBundle/Security/User/HeaderUserProvider.php :

<?php

// src/Security/User/HeaderUserProvider.php
namespace AppBundle\Security\User;

use AppBundle\Security\User\HeaderUser;
use Symfony\Component\Security\Core\User\UserProviderInterface;
use Symfony\Component\Security\Core\User\UserInterface;
use Symfony\Component\Security\Core\Exception\UsernameNotFoundException;
use Symfony\Component\Security\Core\Exception\UnsupportedUserException;

class HeaderUserProvider implements UserProviderInterface
{
    public function loadUserByUsername($username)
    {

        if ($username) {

            $password = "dummy";
            $salt = "";
            $roles = array('ROLE_USER');

            return new HeaderUser($username, $password, $salt, $roles);
        }

        throw new UsernameNotFoundException(
            sprintf('Username "%s" does not exist.', $username)
        );
    }

    public function refreshUser(UserInterface $user)
    {
        if (!$user instanceof HeaderUser) {
            throw new UnsupportedUserException(
                sprintf('Instances of "%s" are not supported.', get_class($user))
            );
        }

        return $this->loadUserByUsername($user->getUsername());
    }

    public function supportsClass($class)
    {
        return HeaderUser::class === $class;
    }
}

?>