Refactor session token management

Relates to https://github.com/shaarli/Shaarli/issues/324

Added:
- `SessionManager` class to group session-related features
- unit tests

Changed:
- `getToken()` -> `SessionManager->generateToken()`
- `tokenOk()` -> `SessionManager->checkToken()`
- inject a `$token` parameter to `PageBuilder`'s constructor

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

2 files changed, 57 insertions, 2 deletions

diff --git a/application/PageBuilder.php b/application/PageBuilder.php
index af290671..468f144b 100644
--- a/application/PageBuilder.php
+++ b/application/PageBuilder.php
@@ -32,12 +32,14 @@ class PageBuilder
      *
      * @param ConfigManager $conf   Configuration Manager instance (reference).
      * @param LinkDB        $linkDB instance.
+     * @param string        $token  Session token
      */
-    public function __construct(&$conf, $linkDB = null)
+    public function __construct(&$conf, $linkDB = null, $token = null)
     {
         $this->tpl = false;
         $this->conf = $conf;
         $this->linkDB = $linkDB;
+        $this->token = $token;
     }
 
     /**
@@ -92,7 +94,7 @@ class PageBuilder
         $this->tpl->assign('showatom', $this->conf->get('feed.show_atom', true));
         $this->tpl->assign('feed_type', $this->conf->get('feed.show_atom', true) !== false ? 'atom' : 'rss');
         $this->tpl->assign('hide_timestamps', $this->conf->get('privacy.hide_timestamps', false));
-        $this->tpl->assign('token', getToken($this->conf));
+        $this->tpl->assign('token', $this->token);
 
         if ($this->linkDB !== null) {
             $this->tpl->assign('tags', $this->linkDB->linksCountPerTag());
diff --git a/application/SessionManager.php b/application/SessionManager.php
new file mode 100644
index 00000000..2083df42
--- /dev/null
+++ b/application/SessionManager.php
@@ -0,0 +1,53 @@
+<?php
+namespace Shaarli;
+
+/**
+ * Manages the server-side session
+ */
+class SessionManager
+{
+    protected $session = [];
+
+    /**
+     * Constructor
+     *
+     * @param array         $session The $_SESSION array (reference)
+     * @param ConfigManager $conf    ConfigManager instance (reference)
+     */
+    public function __construct(& $session, & $conf)
+    {
+        $this->session = &$session;
+        $this->conf = &$conf;
+    }
+
+    /**
+     * Generates a session token
+     *
+     * @return string token
+     */
+    public function generateToken()
+    {
+        $token = sha1(uniqid('', true) .'_'. mt_rand() . $this->conf->get('credentials.salt'));
+        $this->session['tokens'][$token] = 1;
+        return $token;
+    }
+
+    /**
+     * Checks the validity of a session token, and destroys it afterwards
+     *
+     * @param string $token The token to check
+     *
+     * @return bool true if the token is valid, else false
+     */
+    public function checkToken($token)
+    {
+        if (! isset($this->session['tokens'][$token])) {
+            // the token is wrong, or has already been used
+            return false;
+        }
+
+        // destroy the token to prevent future use
+        unset($this->session['tokens'][$token]);
+        return true;
+    }
+}