Add name length check to the HipChatHandler

As explained in its docblock, the validation function will fall back to
a simple strlen check if mb_strlen is not available. However, that very
specific case is not one that was deemed important to support, as anyone
using UTF-8 in their code, without having mbstring available will
probably have bigger problems to worry about.

Fixes #289

src/Monolog/Handler/HipChatHandler.php

@@ -27,6 +27,11 @@ use Monolog\Logger;
  */
 class HipChatHandler extends SocketHandler
 {
+    /**
+     * The maximum allowed length for the name used in the "from" field.
+     */
+    const MAXIMUM_NAME_LENGTH = 15;
+
     /**
      * @var string
      */
@@ -58,6 +63,10 @@ class HipChatHandler extends SocketHandler
      */
     public function __construct($token, $room, $name = 'Monolog', $notify = false, $level = Logger::CRITICAL, $bubble = true, $useSSL = true)
     {
+        if (!$this->validateName($name)) {
+            throw new \InvalidArgumentException('The supplied name is too long. HipChat\'s v1 API supports names up to 15 UTF-8 characters.');
+        }
+
         $connectionString = $useSSL ? 'ssl://api.hipchat.com:443' : 'api.hipchat.com:80';
         parent::__construct($connectionString, $level, $bubble);
 
@@ -216,4 +225,26 @@ class HipChatHandler extends SocketHandler
 
         return $batchRecord;
     }
+
+    /**
+     * Validates the supplied name for the "from" field.
+     *
+     * If the `mb_strlen()` function is available, it will use that, as HipChat
+     * allows UTF-8 characters. Otherwise, it will fall back to `strlen()`.
+     *
+     * Note that this might cause false failures in the specific case of using
+     * a valid name with less than 16 characters, but 16 or more bytes, on a
+     * system where `mb_strlen()` is unavailable.
+     *
+     * @param  string  $name Name to validate
+     * @return Boolean
+     */
+    private function validateName($name)
+    {
+        if (function_exists('mb_strlen')) {
+            return (mb_strlen($name) <= static::MAXIMUM_NAME_LENGTH);
+        }
+
+        return (strlen($name) <= static::MAXIMUM_NAME_LENGTH);
+    }
 }

tests/Monolog/Handler/HipChatHandlerTest.php

@@ -156,4 +156,12 @@ class HipChatHandlerTest extends TestCase
 
         $this->handler->setFormatter($this->getIdentityFormatter());
     }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testCreateWithTooLongName()
+    {
+        $hipChatHandler = new \Monolog\Handler\HipChatHandler('token', 'room', 'SixteenCharsHere');
+    }
 }