From f5616981e8ba043da71a21371c2cbfc5fcb5da56 Mon Sep 17 00:00:00 2001
From: drebs <drebs@leap.se>
Date: Tue, 26 Feb 2013 19:16:09 -0300
Subject: Add auth middleware structure for soledad.

---
 server.py | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 86 insertions(+), 3 deletions(-)

diff --git a/server.py b/server.py
index eb565e9f..4d30a1f8 100644
--- a/server.py
+++ b/server.py
@@ -6,16 +6,91 @@ This should be run with:
 """
 
 import configparser
+from wsgiref.util import shift_path_info
+
 from twisted.web.wsgi import WSGIResource
 from twisted.internet import reactor
+
 from u1db.remote import http_app
+
 from leap.soledad.backends.couch import CouchServerState
 
 
+#-----------------------------------------------------------------------------
+# Authentication
+#-----------------------------------------------------------------------------
+
+class Unauthorized(Exception):
+    """
+    User authentication failed.
+    """
+
+
+class SoledadAuthMiddleware(object):
+    """
+    Soledad Authentication WSGI middleware.
+
+    In general, databases are accessed using a token provided by the LEAP API.
+    Some special databases can be read without authentication.
+    """
+
+    def __init__(self, app, prefix, public_dbs=None):
+        self.app = app
+        self.prefix = prefix
+        self.public_dbs = public_dbs
+
+    def _error(self, start_response, status, description, message=None):
+        start_response("%d %s" % (status, httplib.responses[status]),
+                       [('content-type', 'application/json')])
+        err = {"error": description}
+        if message:
+            err['message'] = message
+        return [json.dumps(err)]
+
+    def __call__(self, environ, start_response):
+        if self.prefix and not environ['PATH_INFO'].startswith(self.prefix):
+            return self._error(start_response, 400, "bad request")
+        token = environ.get('HTTP_AUTHORIZATION')
+        if not token:
+            if need_auth(environ):
+                return self._error(start_response, 401, "unauthorized",
+                                   "Missing Authentication Token.")
+        else:
+            try:
+                self.verify_token(environ, token)
+            except Unauthorized:
+                return self._error(
+                    start_response, 401, "unauthorized",
+                    "Incorrect password or login.")
+            del environ['HTTP_AUTHORIZATION']
+        shift_path_info(environ)
+        return self.app(environ, start_response)
+
+    def verify_token(self, environ, token):
+        """
+        Verify if token is valid for authenticating this action.
+        """
+        # TODO: implement token verification
+        raise NotImplementedError(self.verify_user)
+
+    def need_auth(self, environ):
+        """
+        Check if action can be performed on database without authentication.
+        """
+        # TODO: implement unauth verification.
+        raise NotImplementedError(self.allow_unauth)
+
+
+#-----------------------------------------------------------------------------
+# Auxiliary functions
+#-----------------------------------------------------------------------------
+
 def load_configuration(file_path):
     conf = {
         'couch_url': 'http://localhost:5984',
         'working_dir': '/tmp',
+        'public_dbs': 'keys'
+        'prefix': '/soledad/'
     }
     config = configparser.ConfigParser()
     config.read(file_path)
@@ -23,14 +98,22 @@ def load_configuration(file_path):
         for key in conf:
             if key in config['soledad-server']:
                 conf[key] = config['soledad-server'][key]
+    # TODO: implement basic parsing of options comming from config file.
     return conf
 
 
-conf = load_configuration('/etc/leap/soledad-server.ini')
+#-----------------------------------------------------------------------------
+# Run as Twisted WSGI Resource
+#-----------------------------------------------------------------------------
 
+conf = load_configuration('/etc/leap/soledad-server.ini')
 state = CouchServerState(conf['couch_url'])
-# TODO: change working dir to something meaningful
+# TODO: change working dir to something meaningful (maybe eliminate it)
 state.set_workingdir(conf['working_dir'])
-application = http_app.HTTPApp(state)
+
+application = SoledadAuthMiddleware(
+    http_app.HTTPApp(state),
+    conf['prefix'],
+    conf['public_dbs'].split(','))
 
 resource = WSGIResource(reactor, reactor.getThreadPool(), application)
-- 
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