Merge branch 'security/session-ip-validator'

Fixes issues with proxy server/ip detection.

Fixes zendframework/zendframework#3095

- However, a different approach is taken than that used in that pull request.

src/PhpEnvironment/RemoteAddress.php

@@ -0,0 +1,170 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ * @package   Zend_Http
+ */
+
+namespace Zend\Http\PhpEnvironment;
+
+/**
+ * Functionality for determining client IP address.
+ *
+ * @category   Zend
+ * @package    Zend_Http
+ */
+class RemoteAddress
+{
+    /**
+     * Whether to use proxy addresses or not.
+     *
+     * As default this setting is disabled - IP address is mostly needed to increase
+     * security. HTTP_* are not reliable since can easily be spoofed. It can be enabled
+     * just for more flexibility, but if user uses proxy to connect to trusted services
+     * it's his/her own risk, only reliable field for IP address is $_SERVER['REMOTE_ADDR'].
+     *
+     * @var bool
+     */
+    protected $useProxy = false;
+
+    /**
+     * List of trusted proxy IP addresses
+     *
+     * @var array
+     */
+    protected $trustedProxies = array();
+
+    /**
+     * HTTP header to introspect for proxies
+     *
+     * @var string
+     */
+    protected $proxyHeader = 'HTTP_X_FORWARDED_FOR';
+
+
+    /**
+     * Changes proxy handling setting.
+     *
+     * This must be static method, since validators are recovered automatically
+     * at session read, so this is the only way to switch setting.
+     *
+     * @param  bool  $useProxy Whether to check also proxied IP addresses.
+     * @return RemoteAddress
+     */
+    public function setUseProxy($useProxy = true)
+    {
+        $this->useProxy = $useProxy;
+        return $this;
+    }
+
+    /**
+     * Checks proxy handling setting.
+     *
+     * @return bool Current setting value.
+     */
+    public function getUseProxy()
+    {
+        return $this->useProxy;
+    }
+
+    /**
+     * Set list of trusted proxy addresses
+     *
+     * @param  array $trustedProxies
+     * @return RemoteAddress
+     */
+    public function setTrustedProxies(array $trustedProxies)
+    {
+        $this->trustedProxies = $trustedProxies;
+        return $this;
+    }
+
+    /**
+     * Set the header to introspect for proxy IPs
+     *
+     * @param  string $header
+     * @return RemoteAddress
+     */
+    public function setProxyHeader($header = 'X-Forwarded-For')
+    {
+        $this->proxyHeader = $this->normalizeProxyHeader($header);
+        return $this;
+    }
+
+    /**
+     * Returns client IP address.
+     *
+     * @return string IP address.
+     */
+    public function getIpAddress()
+    {
+        $ip = $this->getIpAddressFromProxy();
+        if ($ip) {
+            return $ip;
+        }
+
+        // direct IP address
+        if (isset($_SERVER['REMOTE_ADDR'])) {
+            return $_SERVER['REMOTE_ADDR'];
+        }
+
+        return '';
+    }
+
+    /**
+     * Attempt to get the IP address for a proxied client
+     *
+     * @return false|string
+     */
+    protected function getIpAddressFromProxy()
+    {
+        if (!$this->useProxy) {
+            return false;
+        }
+
+        $header = $this->proxyHeader;
+
+        if (!isset($_SERVER[$header]) || empty($_SERVER[$header])) {
+            return false;
+        }
+
+        // Extract IPs
+        $ips = explode(',', $_SERVER[$header]);
+        // trim, so we can compare against trusted proxies properly
+        $ips = array_map('trim', $ips);
+        // remove trusted proxy IPs
+        $ips = array_diff($ips, $this->trustedProxies);
+
+        // Any left?
+        if (empty($ips)) {
+            return false;
+        }
+
+        // Return right-most
+        $ip  = array_pop($ips);
+        return $ip;
+    }
+
+
+    /**
+     * Normalize a header string
+     *
+     * Normalizes a header string to a format that is compatible with
+     * $_SERVER
+     *
+     * @param  string $header
+     * @return string
+     */
+    protected function normalizeProxyHeader($header)
+    {
+        $header = strtoupper($header);
+        $header = str_replace('-', '_', $header);
+        if (0 !== strpos($header, 'HTTP_')) {
+            $header = 'HTTP_' . $header;
+        }
+        return $header;
+    }
+}