Add basic, untested skeleton for Session and PHPSession

As we decided to remove Zend_Session due to locking issues,
we have to implement our session handling here. This is
the basic, untested code which will be tested in the next step

refs #4265

library/Icinga/Authentication/PHPSession.php

@@ -0,0 +1,118 @@
+<?php
+
+namespace Icinga\Authentication;
+
+use Icinga\Application\Logger as Logger;
+
+class PhpSession extends Session
+{
+    const SESSION_NAME = "Icinga2Web";
+    private $isOpen = false;
+    private $isFlushed = false;
+    
+    private static $DEFAULT_COOKIEOPTIONS = array(
+        'use_trans_sid'           => false,
+        'use_cookies'             => true,
+        'use_only_cooies'         => true,
+        'cookie_httponly'         => true,
+        'use_only_cookies'        => true,
+        'hash_function'           => true,
+        'hash_bits_per_character' => 5,
+    );
+
+
+    public function __construct(array $options = null)
+    {
+        if ($options !== null) {
+            $options = array_merge(PhpSession::DEFAULT_COOKIEOPTIONS, $options);
+        }
+        foreach ($options as $sessionVar => $value) {
+            if (ini_set("session.".$sessionVar, $value) === false) {
+                Logger::warn("Could not set php.ini settint %s = %s", $sessionVar, $value);
+            }
+        }
+    }
+
+    private function sessionCanBeChanged()
+    {
+        if ($this->isFlushed) {
+            Logger::error("Tried to work on a closed session, session changes will be ignored");
+            return false;
+        }
+        return true;
+    }
+    
+    private function sessionCanBeOpened()
+    {
+        if ($this->isOpen) {
+            Logger::warn("Tried to open a session more than once");
+            return false;
+        }
+        return $this->sessionCanBeChanged();
+    }
+ 
+    public function open()
+    {
+        if (!$this->sessionCanBeOpened()) {
+            return false;
+        }
+            
+        session_name(PhpSession::SESSION_NAME);
+        session_start();
+        $this->isOpen = true;
+        $this->setAll($_SESSION);
+        return true;
+    }
+  
+    private function ensureOpen()
+    {
+        // try to open first
+        if (!$this->isOpen) {
+            if (!$this->open()) {
+                return false;
+            }
+        }
+        return true;
+    }
+ 
+    public function read($keepOpen = false)
+    {
+        if (!$this->ensureOpen) {
+            return false;
+        }
+        if ($keepOpen) {
+            return true;
+        }
+        $this->close();
+        return true;
+    }
+ 
+    public function write($keepOpen = false)
+    {
+        if (!$this->ensureOpen) {
+            return false;
+        }
+        foreach ($this->getAll() as $key => $value) {
+            $_SESSION[$key] = $value;
+        }
+        if ($keepOpen) {
+            return;
+        }
+        $this->close();
+    }
+    
+    public function close()
+    {
+        if (!$this->isFlushed) {
+            session_write_close();
+        }
+        $this->isFlushed = true;
+    }
+
+    public function purge()
+    {
+        if (!$this->ensureOpen() && !$this->isFlushed) {
+            session_destroy();
+        }
+    }
+}

library/Icinga/Authentication/Session.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace Icinga\Authentication;
+
+abstract class Session
+{
+    private $sessionValues = array();
+    
+    
+    abstract public function open();
+    abstract public function read($keepOpen = false);
+    abstract public function write($keepOpen = false);
+    abstract public function close();
+    abstract public function purge();
+
+    public function set($key, $value)
+    {
+        $this->sessionValues[$key] = $value;
+    }
+
+    public function get($key, $defaultValue = null)
+    {
+        return isset($this->sessionValues[$key]) ?
+            $this->sessionValues[$key] : $defaultValue;
+    }
+
+    public function getAll()
+    {
+        return $this->sessionValues;
+    }
+
+    public function setAll(array $values, $overwrite = false)
+    {
+        if ($overwrite) {
+            $this->clear();
+        }
+        foreach ($values as $key => $value) {
+            if (isset($this->sessionValues[$key]) && !$overwrite) {
+                continue;
+            }
+            $this->sessionValues[$key] = $value;
+        }
+    }
+
+    public function clear()
+    {
+        $this->sessionValues = array();
+    }
+}