Session ID: extend the regex to match possible hash representations

Improves #306
Relates to #335 & #336
Duplicated by #339

Issues:
 - PHP regenerates the session ID if it is not compliant
 - the regex checking the session ID does not cover all cases
   - different algorithms: md5, sha1, sha256, etc.
   - bit representations: 4, 5, 6

Fix:
 - `index.php`:
   - remove `uniqid()` usage
   - call `session_regenerate_id()` if an invalid cookie is detected
 - regex: support all possible characters - '[a-zA-Z,-]{2,128}'
 - tests: add coverage for all algorithms & bit representations

See:
 - http://php.net/manual/en/session.configuration.php#ini.session.hash-function
 - https://secure.php.net/manual/en/session.configuration.php#ini.session.hash-bits-per-character
 - http://php.net/manual/en/function.session-id.php
 - http://php.net/manual/en/function.session-regenerate-id.php
 - http://php.net/manual/en/function.hash-algos.php

Signed-off-by: VirtualTam <virtualtam@flibidi.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/application/Utils.php b/application/Utils.php
index cb03f11c..1422961d 100755
--- a/application/Utils.php
+++ b/application/Utils.php
@@ -140,11 +140,16 @@ function checkPHPVersion($minVersion, $curVersion)
 
 /**
  * Validate session ID to prevent Full Path Disclosure.
+ *
  * See #298.
+ * The session ID's format depends on the hash algorithm set in PHP settings
  *
  * @param string $sessionId Session ID
  *
  * @return true if valid, false otherwise.
+ *
+ * @see http://php.net/manual/en/function.hash-algos.php
+ * @see http://php.net/manual/en/session.configuration.php
  */
 function is_session_id_valid($sessionId)
 {
@@ -156,7 +161,7 @@ function is_session_id_valid($sessionId)
         return false;
     }
 
-    if (!preg_match('/^[a-z0-9]{2,32}$/i', $sessionId)) {
+    if (!preg_match('/^[a-zA-Z0-9,-]{2,128}$/', $sessionId)) {
         return false;
     }