Notebook: Store the username in a cookie whose name is unique.

Cookies cannot be saved on a per-port basis, so a cookie "username" is
shared across all running IPython notebooks with the same hostname.
Using a unique cookie name prevents this collision.

This allows a user to start multiple IPython notebooks and be logged into
each.

IPython/frontend/html/notebook/handlers.py

@@ -146,13 +146,13 b' class AuthenticatedHandler(RequestHandler):'
     """A RequestHandler with an authenticated user."""
 
     def get_current_user(self):
-        user_id = self.get_secure_cookie("username")
+        user_id = self.get_secure_cookie(self.settings['cookie_name'])
         # For now the user_id should not return empty, but it could eventually
         if user_id == '':
             user_id = 'anonymous'
         if user_id is None:
             # prevent extra Invalid cookie sig warnings:
-            self.clear_cookie('username')
+            self.clear_cookie(self.settings['cookie_name'])
             if not self.application.password and not self.application.read_only:
                 user_id = 'anonymous'
         return user_id
@@ -242,7 +242,7 b' class LoginHandler(AuthenticatedHandler):'
         pwd = self.get_argument('password', default=u'')
         if self.application.password:
             if passwd_check(self.application.password, pwd):
-                self.set_secure_cookie('username', str(uuid.uuid4()))
+                self.set_secure_cookie(self.settings['cookie_name'], str(uuid.uuid4()))
             else:
                 self._render(message={'error': 'Invalid password'})
                 return
@@ -253,7 +253,7 b' class LoginHandler(AuthenticatedHandler):'
 class LogoutHandler(AuthenticatedHandler):
 
     def get(self):
-        self.clear_cookie('username')
+        self.clear_cookie(self.settings['cookie_name'])
         if self.login_available:
             message = {'info': 'Successfully logged out.'}
         else:
@@ -427,7 +427,7 b' class AuthenticatedZMQStreamHandler(ZMQStreamHandler):'
         self.on_message = self.on_first_message
 
     def get_current_user(self):
-        user_id = self.get_secure_cookie("username")
+        user_id = self.get_secure_cookie(self.settings['cookie_name'])
         if user_id == '' or (user_id is None and not self.application.password):
             user_id = 'anonymous'
         return user_id

IPython/frontend/html/notebook/notebookapp.py

@@ -28,6 +28,7 b' import socket'
 import sys
 import threading
 import time
+import uuid
 import webbrowser
 
 # Third party
@@ -164,6 +165,7 b' class NotebookWebApplication(web.Application):'
             static_handler_class = FileFindHandler,
             cookie_secret=os.urandom(1024),
             login_url="%s/login"%(base_project_url.rstrip('/')),
+            cookie_name='username-%s' % uuid.uuid4(),
         )
 
         # allow custom overrides for the tornado web app.