From d886f6db164022d92b17cbb55f8ae2d44bc23bc7 Mon Sep 17 00:00:00 2001
From: Alex Tselegidis <alextselegidis@gmail.com>
Date: Fri, 29 Oct 2021 13:06:56 +0200
Subject: [PATCH] Override the CSRF validation to support the X-CSRF header.

---
 application/core/EA_Security.php | 56 +++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/application/core/EA_Security.php b/application/core/EA_Security.php
index ed7edae5..44046de0 100644
--- a/application/core/EA_Security.php
+++ b/application/core/EA_Security.php
@@ -40,5 +40,59 @@
  * @property EA_URI $uri
  */
 class EA_Security extends CI_Security {
-    // 
+    /**
+     * CSRF Verify
+     *
+     * @return    CI_Security
+     */
+    public function csrf_verify()
+    {
+        // If it's not a POST request we will set the CSRF cookie
+        if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST')
+        {
+            return $this->csrf_set_cookie();
+        }
+
+        // Check if URI has been whitelisted from CSRF checks
+        if ($exclude_uris = config_item('csrf_exclude_uris'))
+        {
+            $uri = load_class('URI', 'core');
+            foreach ($exclude_uris as $excluded)
+            {
+                if (preg_match('#^' . $excluded . '$#i' . (UTF8_ENABLED ? 'u' : ''), $uri->uri_string()))
+                {
+                    return $this;
+                }
+            }
+        }
+
+        // Check CSRF token validity, but don't error on mismatch just yet - we'll want to regenerate
+        $csrf_token = $_POST[$this->_csrf_token_name] ?? $_SERVER['HTTP_X_CSRF'] ?? NULL;
+
+        $valid = isset($csrf_token, $_COOKIE[$this->_csrf_cookie_name])
+            && is_string($csrf_token) && is_string($_COOKIE[$this->_csrf_cookie_name])
+            && hash_equals($csrf_token, $_COOKIE[$this->_csrf_cookie_name]);
+
+        // We kill this since we're done and we don't want to pollute the _POST array
+        unset($_POST[$this->_csrf_token_name]);
+
+        // Regenerate on every submission?
+        if (config_item('csrf_regenerate'))
+        {
+            // Nothing should last forever
+            unset($_COOKIE[$this->_csrf_cookie_name]);
+            $this->_csrf_hash = NULL;
+        }
+
+        $this->_csrf_set_hash();
+        $this->csrf_set_cookie();
+
+        if ($valid !== TRUE)
+        {
+            $this->csrf_show_error();
+        }
+
+        log_message('info', 'CSRF token verified');
+        return $this;
+    }
 }