Merge branch 'develop' of github.com:matrix-org/synapse into erikj/fix_email_notifs

13 files changed, 712 insertions, 498 deletions

diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 27599124d2..1b3b55d517 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -1001,16 +1001,6 @@ class Auth(object):
                         403,
                         "You are not allowed to set others state"
                     )
-                else:
-                    sender_domain = UserID.from_string(
-                        event.user_id
-                    ).domain
-
-                    if sender_domain != event.state_key:
-                        raise AuthError(
-                            403,
-                            "You are not allowed to set others state"
-                        )
 
         return True
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index d59f4a571c..1a6f5507a9 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -197,7 +197,7 @@ class PusherServer(HomeServer):
                     yield start_pusher(user_id, app_id, pushkey)
 
             stream = results.get("events")
-            if stream:
+            if stream and stream["rows"]:
                 min_stream_id = stream["rows"][0][0]
                 max_stream_id = stream["position"]
                 preserve_fn(pusher_pool.on_new_notifications)(
@@ -205,7 +205,7 @@ class PusherServer(HomeServer):
                 )
 
             stream = results.get("receipts")
-            if stream:
+            if stream and stream["rows"]:
                 rows = stream["rows"]
                 affected_room_ids = set(row[1] for row in rows)
                 min_stream_id = rows[0][0]
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 79b0534b3b..0f890fc04a 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -30,7 +30,7 @@ from .saml2 import SAML2Config
 from .cas import CasConfig
 from .password import PasswordConfig
 from .jwt import JWTConfig
-from .ldap import LDAPConfig
+from .password_auth_providers import PasswordAuthProviderConfig
 from .emailconfig import EmailConfig
 from .workers import WorkerConfig
 
@@ -39,8 +39,8 @@ class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        RatelimitConfig, ContentRepositoryConfig, CaptchaConfig,
                        VoipConfig, RegistrationConfig, MetricsConfig, ApiConfig,
                        AppServiceConfig, KeyConfig, SAML2Config, CasConfig,
-                       JWTConfig, LDAPConfig, PasswordConfig, EmailConfig,
-                       WorkerConfig,):
+                       JWTConfig, PasswordConfig, EmailConfig,
+                       WorkerConfig, PasswordAuthProviderConfig,):
     pass
 
 
diff --git a/synapse/config/ldap.py b/synapse/config/ldap.py
deleted file mode 100644
index d83c2230be..0000000000
--- a/synapse/config/ldap.py
+++ /dev/null
@@ -1,100 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015 Niklas Riekenbrauck
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from ._base import Config, ConfigError
-
-
-MISSING_LDAP3 = (
-    "Missing ldap3 library. This is required for LDAP Authentication."
-)
-
-
-class LDAPMode(object):
-    SIMPLE = "simple",
-    SEARCH = "search",
-
-    LIST = (SIMPLE, SEARCH)
-
-
-class LDAPConfig(Config):
-    def read_config(self, config):
-        ldap_config = config.get("ldap_config", {})
-
-        self.ldap_enabled = ldap_config.get("enabled", False)
-
-        if self.ldap_enabled:
-            # verify dependencies are available
-            try:
-                import ldap3
-                ldap3  # to stop unused lint
-            except ImportError:
-                raise ConfigError(MISSING_LDAP3)
-
-            self.ldap_mode = LDAPMode.SIMPLE
-
-            # verify config sanity
-            self.require_keys(ldap_config, [
-                "uri",
-                "base",
-                "attributes",
-            ])
-
-            self.ldap_uri = ldap_config["uri"]
-            self.ldap_start_tls = ldap_config.get("start_tls", False)
-            self.ldap_base = ldap_config["base"]
-            self.ldap_attributes = ldap_config["attributes"]
-
-            if "bind_dn" in ldap_config:
-                self.ldap_mode = LDAPMode.SEARCH
-                self.require_keys(ldap_config, [
-                    "bind_dn",
-                    "bind_password",
-                ])
-
-                self.ldap_bind_dn = ldap_config["bind_dn"]
-                self.ldap_bind_password = ldap_config["bind_password"]
-                self.ldap_filter = ldap_config.get("filter", None)
-
-            # verify attribute lookup
-            self.require_keys(ldap_config['attributes'], [
-                "uid",
-                "name",
-                "mail",
-            ])
-
-    def require_keys(self, config, required):
-        missing = [key for key in required if key not in config]
-        if missing:
-            raise ConfigError(
-                "LDAP enabled but missing required config values: {}".format(
-                    ", ".join(missing)
-                )
-            )
-
-    def default_config(self, **kwargs):
-        return """\
-        # ldap_config:
-        #   enabled: true
-        #   uri: "ldap://ldap.example.com:389"
-        #   start_tls: true
-        #   base: "ou=users,dc=example,dc=com"
-        #   attributes:
-        #      uid: "cn"
-        #      mail: "email"
-        #      name: "givenName"
-        #   #bind_dn:
-        #   #bind_password:
-        #   #filter: "(objectClass=posixAccount)"
-        """
diff --git a/synapse/config/password_auth_providers.py b/synapse/config/password_auth_providers.py
new file mode 100644
index 0000000000..f6d9bb1c62
--- /dev/null
+++ b/synapse/config/password_auth_providers.py
@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 Openmarket
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ._base import Config
+
+import importlib
+
+
+class PasswordAuthProviderConfig(Config):
+    def read_config(self, config):
+        self.password_providers = []
+
+        # We want to be backwards compatible with the old `ldap_config`
+        # param.
+        ldap_config = config.get("ldap_config", {})
+        self.ldap_enabled = ldap_config.get("enabled", False)
+        if self.ldap_enabled:
+            from synapse.util.ldap_auth_provider import LdapAuthProvider
+            parsed_config = LdapAuthProvider.parse_config(ldap_config)
+            self.password_providers.append((LdapAuthProvider, parsed_config))
+
+        providers = config.get("password_providers", [])
+        for provider in providers:
+            # We need to import the module, and then pick the class out of
+            # that, so we split based on the last dot.
+            module, clz = provider['module'].rsplit(".", 1)
+            module = importlib.import_module(module)
+            provider_class = getattr(module, clz)
+
+            provider_config = provider_class.parse_config(provider["config"])
+            self.password_providers.append((provider_class, provider_config))
+
+    def default_config(self, **kwargs):
+        return """\
+        # password_providers:
+        #     - module: "synapse.util.ldap_auth_provider.LdapAuthProvider"
+        #       config:
+        #         enabled: true
+        #         uri: "ldap://ldap.example.com:389"
+        #         start_tls: true
+        #         base: "ou=users,dc=example,dc=com"
+        #         attributes:
+        #            uid: "cn"
+        #            mail: "email"
+        #            name: "givenName"
+        #         #bind_dn:
+        #         #bind_password:
+        #         #filter: "(objectClass=posixAccount)"
+        """
diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index fac8550823..3c58d2de17 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -19,6 +19,9 @@ from OpenSSL import crypto
 import subprocess
 import os
 
+from hashlib import sha256
+from unpaddedbase64 import encode_base64
+
 GENERATE_DH_PARAMS = False
 
 
@@ -42,6 +45,19 @@ class TlsConfig(Config):
             config.get("tls_dh_params_path"), "tls_dh_params"
         )
 
+        self.tls_fingerprints = config["tls_fingerprints"]
+
+        # Check that our own certificate is included in the list of fingerprints
+        # and include it if it is not.
+        x509_certificate_bytes = crypto.dump_certificate(
+            crypto.FILETYPE_ASN1,
+            self.tls_certificate
+        )
+        sha256_fingerprint = encode_base64(sha256(x509_certificate_bytes).digest())
+        sha256_fingerprints = set(f["sha256"] for f in self.tls_fingerprints)
+        if sha256_fingerprint not in sha256_fingerprints:
+            self.tls_fingerprints.append({u"sha256": sha256_fingerprint})
+
         # This config option applies to non-federation HTTP clients
         # (e.g. for talking to recaptcha, identity servers, and such)
         # It should never be used in production, and is intended for
@@ -73,6 +89,28 @@ class TlsConfig(Config):
 
         # Don't bind to the https port
         no_tls: False
+
+        # List of allowed TLS fingerprints for this server to publish along
+        # with the signing keys for this server. Other matrix servers that
+        # make HTTPS requests to this server will check that the TLS
+        # certificates returned by this server match one of the fingerprints.
+        #
+        # Synapse automatically adds its the fingerprint of its own certificate
+        # to the list. So if federation traffic is handle directly by synapse
+        # then no modification to the list is required.
+        #
+        # If synapse is run behind a load balancer that handles the TLS then it
+        # will be necessary to add the fingerprints of the certificates used by
+        # the loadbalancers to this list if they are different to the one
+        # synapse is using.
+        #
+        # Homeservers are permitted to cache the list of TLS fingerprints
+        # returned in the key responses up to the "valid_until_ts" returned in
+        # key. It may be necessary to publish the fingerprints of a new
+        # certificate and wait until the "valid_until_ts" of the previous key
+        # responses have passed before deploying it.
+        tls_fingerprints: []
+        # tls_fingerprints: [{"sha256": "<base64_encoded_sha256_fingerprint>"}]
         """ % locals()
 
     def read_tls_certificate(self, cert_path):
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 3933ce171a..dc0fe60e1b 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -20,7 +20,6 @@ from synapse.api.constants import LoginType
 from synapse.types import UserID
 from synapse.api.errors import AuthError, LoginError, Codes, StoreError, SynapseError
 from synapse.util.async import run_on_reactor
-from synapse.config.ldap import LDAPMode
 
 from twisted.web.client import PartialDownloadError
 
@@ -29,13 +28,6 @@ import bcrypt
 import pymacaroons
 import simplejson
 
-try:
-    import ldap3
-    import ldap3.core.exceptions
-except ImportError:
-    ldap3 = None
-    pass
-
 import synapse.util.stringutils as stringutils
 
 
@@ -59,23 +51,15 @@ class AuthHandler(BaseHandler):
         }
         self.bcrypt_rounds = hs.config.bcrypt_rounds
         self.sessions = {}
-        self.INVALID_TOKEN_HTTP_STATUS = 401
 
-        self.ldap_enabled = hs.config.ldap_enabled
-        if self.ldap_enabled:
-            if not ldap3:
-                raise RuntimeError(
-                    'Missing ldap3 library. This is required for LDAP Authentication.'
-                )
-            self.ldap_mode = hs.config.ldap_mode
-            self.ldap_uri = hs.config.ldap_uri
-            self.ldap_start_tls = hs.config.ldap_start_tls
-            self.ldap_base = hs.config.ldap_base
-            self.ldap_attributes = hs.config.ldap_attributes
-            if self.ldap_mode == LDAPMode.SEARCH:
-                self.ldap_bind_dn = hs.config.ldap_bind_dn
-                self.ldap_bind_password = hs.config.ldap_bind_password
-                self.ldap_filter = hs.config.ldap_filter
+        account_handler = _AccountHandler(
+            hs, check_user_exists=self.check_user_exists
+        )
+
+        self.password_providers = [
+            module(config=config, account_handler=account_handler)
+            for module, config in hs.config.password_providers
+        ]
 
         self.hs = hs  # FIXME better possibility to access registrationHandler later?
         self.device_handler = hs.get_device_handler()
@@ -149,13 +133,30 @@ class AuthHandler(BaseHandler):
         creds = session['creds']
 
         # check auth type currently being presented
+        errordict = {}
         if 'type' in authdict:
-            if authdict['type'] not in self.checkers:
+            login_type = authdict['type']
+            if login_type not in self.checkers:
                 raise LoginError(400, "", Codes.UNRECOGNIZED)
-            result = yield self.checkers[authdict['type']](authdict, clientip)
-            if result:
-                creds[authdict['type']] = result
-                self._save_session(session)
+            try:
+                result = yield self.checkers[login_type](authdict, clientip)
+                if result:
+                    creds[login_type] = result
+                    self._save_session(session)
+            except LoginError, e:
+                if login_type == LoginType.EMAIL_IDENTITY:
+                    # riot used to have a bug where it would request a new
+                    # validation token (thus sending a new email) each time it
+                    # got a 401 with a 'flows' field.
+                    # (https://github.com/vector-im/vector-web/issues/2447).
+                    #
+                    # Grandfather in the old behaviour for now to avoid
+                    # breaking old riot deployments.
+                    raise e
+
+                # this step failed. Merge the error dict into the response
+                # so that the client can have another go.
+                errordict = e.error_dict()
 
         for f in flows:
             if len(set(f) - set(creds.keys())) == 0:
@@ -164,6 +165,7 @@ class AuthHandler(BaseHandler):
 
         ret = self._auth_dict_for_flows(flows, session)
         ret['completed'] = creds.keys()
+        ret.update(errordict)
         defer.returnValue((False, ret, clientdict, session['id']))
 
     @defer.inlineCallbacks
@@ -431,37 +433,40 @@ class AuthHandler(BaseHandler):
             defer.Deferred: (str) canonical_user_id, or None if zero or
             multiple matches
         """
-        try:
-            res = yield self._find_user_id_and_pwd_hash(user_id)
+        res = yield self._find_user_id_and_pwd_hash(user_id)
+        if res is not None:
             defer.returnValue(res[0])
-        except LoginError:
-            defer.returnValue(None)
+        defer.returnValue(None)
 
     @defer.inlineCallbacks
     def _find_user_id_and_pwd_hash(self, user_id):
         """Checks to see if a user with the given id exists. Will check case
-        insensitively, but will throw if there are multiple inexact matches.
+        insensitively, but will return None if there are multiple inexact
+        matches.
 
         Returns:
             tuple: A 2-tuple of `(canonical_user_id, password_hash)`
+            None: if there is not exactly one match
         """
         user_infos = yield self.store.get_users_by_id_case_insensitive(user_id)
+
+        result = None
         if not user_infos:
             logger.warn("Attempted to login as %s but they do not exist", user_id)
-            raise LoginError(403, "", errcode=Codes.FORBIDDEN)
-
-        if len(user_infos) > 1:
-            if user_id not in user_infos:
-                logger.warn(
-                    "Attempted to login as %s but it matches more than one user "
-                    "inexactly: %r",
-                    user_id, user_infos.keys()
-                )
-                raise LoginError(403, "", errcode=Codes.FORBIDDEN)
-
-            defer.returnValue((user_id, user_infos[user_id]))
+        elif len(user_infos) == 1:
+            # a single match (possibly not exact)
+            result = user_infos.popitem()
+        elif user_id in user_infos:
+            # multiple matches, but one is exact
+            result = (user_id, user_infos[user_id])
         else:
-            defer.returnValue(user_infos.popitem())
+            # multiple matches, none of them exact
+            logger.warn(
+                "Attempted to login as %s but it matches more than one user "
+                "inexactly: %r",
+                user_id, user_infos.keys()
+            )
+        defer.returnValue(result)
 
     @defer.inlineCallbacks
     def _check_password(self, user_id, password):
@@ -475,305 +480,48 @@ class AuthHandler(BaseHandler):
         Returns:
             (str) the canonical_user_id
         Raises:
-            LoginError if the password was incorrect
+            LoginError if login fails
         """
-        valid_ldap = yield self._check_ldap_password(user_id, password)
-        if valid_ldap:
-            defer.returnValue(user_id)
-
-        result = yield self._check_local_password(user_id, password)
-        defer.returnValue(result)
+        for provider in self.password_providers:
+            is_valid = yield provider.check_password(user_id, password)
+            if is_valid:
+                defer.returnValue(user_id)
+
+        canonical_user_id = yield self._check_local_password(user_id, password)
+
+        if canonical_user_id:
+            defer.returnValue(canonical_user_id)
+
+        # unknown username or invalid password. We raise a 403 here, but note
+        # that if we're doing user-interactive login, it turns all LoginErrors
+        # into a 401 anyway.
+        raise LoginError(
+            403, "Invalid password",
+            errcode=Codes.FORBIDDEN
+        )
 
     @defer.inlineCallbacks
     def _check_local_password(self, user_id, password):
         """Authenticate a user against the local password database.
 
-        user_id is checked case insensitively, but will throw if there are
+        user_id is checked case insensitively, but will return None if there are
         multiple inexact matches.
 
         Args:
             user_id (str): complete @user:id
         Returns:
-            (str) the canonical_user_id
-        Raises:
-            LoginError if the password was incorrect
+            (str) the canonical_user_id, or None if unknown user / bad password
         """
-        user_id, password_hash = yield self._find_user_id_and_pwd_hash(user_id)
+        lookupres = yield self._find_user_id_and_pwd_hash(user_id)
+        if not lookupres:
+            defer.returnValue(None)
+        (user_id, password_hash) = lookupres
         result = self.validate_hash(password, password_hash)
         if not result:
             logger.warn("Failed password login for user %s", user_id)
-            raise LoginError(403, "", errcode=Codes.FORBIDDEN)
+            defer.returnValue(None)
         defer.returnValue(user_id)
 
-    def _ldap_simple_bind(self, server, localpart, password):
-        """ Attempt a simple bind with the credentials
-            given by the user against the LDAP server.
-
-            Returns True, LDAP3Connection
-                if the bind was successful
-            Returns False, None
-                if an error occured
-        """
-
-        try:
-            # bind with the the local users ldap credentials
-            bind_dn = "{prop}={value},{base}".format(
-                prop=self.ldap_attributes['uid'],
-                value=localpart,
-                base=self.ldap_base
-            )
-            conn = ldap3.Connection(server, bind_dn, password)
-            logger.debug(
-                "Established LDAP connection in simple bind mode: %s",
-                conn
-            )
-
-            if self.ldap_start_tls:
-                conn.start_tls()
-                logger.debug(
-                    "Upgraded LDAP connection in simple bind mode through StartTLS: %s",
-                    conn
-                )
-
-            if conn.bind():
-                # GOOD: bind okay
-                logger.debug("LDAP Bind successful in simple bind mode.")
-                return True, conn
-
-            # BAD: bind failed
-            logger.info(
-                "Binding against LDAP failed for '%s' failed: %s",
-                localpart, conn.result['description']
-            )
-            conn.unbind()
-            return False, None
-
-        except ldap3.core.exceptions.LDAPException as e:
-            logger.warn("Error during LDAP authentication: %s", e)
-            return False, None
-
-    def _ldap_authenticated_search(self, server, localpart, password):
-        """ Attempt to login with the preconfigured bind_dn
-            and then continue searching and filtering within
-            the base_dn
-
-            Returns (True, LDAP3Connection)
-                if a single matching DN within the base was found
-                that matched the filter expression, and with which
-                a successful bind was achieved
-
-                The LDAP3Connection returned is the instance that was used to
-                verify the password not the one using the configured bind_dn.
-            Returns (False, None)
-                if an error occured
-        """
-
-        try:
-            conn = ldap3.Connection(
-                server,
-                self.ldap_bind_dn,
-                self.ldap_bind_password
-            )
-            logger.debug(
-                "Established LDAP connection in search mode: %s",
-                conn
-            )
-
-            if self.ldap_start_tls:
-                conn.start_tls()
-                logger.debug(
-                    "Upgraded LDAP connection in search mode through StartTLS: %s",
-                    conn
-                )
-
-            if not conn.bind():
-                logger.warn(
-                    "Binding against LDAP with `bind_dn` failed: %s",
-                    conn.result['description']
-                )
-                conn.unbind()
-                return False, None
-
-            # construct search_filter like (uid=localpart)
-            query = "({prop}={value})".format(
-                prop=self.ldap_attributes['uid'],
-                value=localpart
-            )
-            if self.ldap_filter:
-                # combine with the AND expression
-                query = "(&{query}{filter})".format(
-                    query=query,
-                    filter=self.ldap_filter
-                )
-            logger.debug(
-                "LDAP search filter: %s",
-                query
-            )
-            conn.search(
-                search_base=self.ldap_base,
-                search_filter=query
-            )
-
-            if len(conn.response) == 1:
-                # GOOD: found exactly one result
-                user_dn = conn.response[0]['dn']
-                logger.debug('LDAP search found dn: %s', user_dn)
-
-                # unbind and simple bind with user_dn to verify the password
-                # Note: do not use rebind(), for some reason it did not verify
-                #       the password for me!
-                conn.unbind()
-                return self._ldap_simple_bind(server, localpart, password)
-            else:
-                # BAD: found 0 or > 1 results, abort!
-                if len(conn.response) == 0:
-                    logger.info(
-                        "LDAP search returned no results for '%s'",
-                        localpart
-                    )
-                else:
-                    logger.info(
-                        "LDAP search returned too many (%s) results for '%s'",
-                        len(conn.response), localpart
-                    )
-                conn.unbind()
-                return False, None
-
-        except ldap3.core.exceptions.LDAPException as e:
-            logger.warn("Error during LDAP authentication: %s", e)
-            return False, None
-
-    @defer.inlineCallbacks
-    def _check_ldap_password(self, user_id, password):
-        """ Attempt to authenticate a user against an LDAP Server
-            and register an account if none exists.
-
-            Returns:
-                True if authentication against LDAP was successful
-        """
-
-        if not ldap3 or not self.ldap_enabled:
-            defer.returnValue(False)
-
-        localpart = UserID.from_string(user_id).localpart
-
-        try:
-            server = ldap3.Server(self.ldap_uri)
-            logger.debug(
-                "Attempting LDAP connection with %s",
-                self.ldap_uri
-            )
-
-            if self.ldap_mode == LDAPMode.SIMPLE:
-                result, conn = self._ldap_simple_bind(
-                    server=server, localpart=localpart, password=password
-                )
-                logger.debug(
-                    'LDAP authentication method simple bind returned: %s (conn: %s)',
-                    result,
-                    conn
-                )
-                if not result:
-                    defer.returnValue(False)
-            elif self.ldap_mode == LDAPMode.SEARCH:
-                result, conn = self._ldap_authenticated_search(
-                    server=server, localpart=localpart, password=password
-                )
-                logger.debug(
-                    'LDAP auth method authenticated search returned: %s (conn: %s)',
-                    result,
-                    conn
-                )
-                if not result:
-                    defer.returnValue(False)
-            else:
-                raise RuntimeError(
-                    'Invalid LDAP mode specified: {mode}'.format(
-                        mode=self.ldap_mode
-                    )
-                )
-
-            try:
-                logger.info(
-                    "User authenticated against LDAP server: %s",
-                    conn
-                )
-            except NameError:
-                logger.warn("Authentication method yielded no LDAP connection, aborting!")
-                defer.returnValue(False)
-
-            # check if user with user_id exists
-            if (yield self.check_user_exists(user_id)):
-                # exists, authentication complete
-                conn.unbind()
-                defer.returnValue(True)
-
-            else:
-                # does not exist, fetch metadata for account creation from
-                # existing ldap connection
-                query = "({prop}={value})".format(
-                    prop=self.ldap_attributes['uid'],
-                    value=localpart
-                )
-
-                if self.ldap_mode == LDAPMode.SEARCH and self.ldap_filter:
-                    query = "(&{filter}{user_filter})".format(
-                        filter=query,
-                        user_filter=self.ldap_filter
-                    )
-                logger.debug(
-                    "ldap registration filter: %s",
-                    query
-                )
-
-                conn.search(
-                    search_base=self.ldap_base,
-                    search_filter=query,
-                    attributes=[
-                        self.ldap_attributes['name'],
-                        self.ldap_attributes['mail']
-                    ]
-                )
-
-                if len(conn.response) == 1:
-                    attrs = conn.response[0]['attributes']
-                    mail = attrs[self.ldap_attributes['mail']][0]
-                    name = attrs[self.ldap_attributes['name']][0]
-
-                    # create account
-                    registration_handler = self.hs.get_handlers().registration_handler
-                    user_id, access_token = (
-                        yield registration_handler.register(localpart=localpart)
-                    )
-
-                    # TODO: bind email, set displayname with data from ldap directory
-
-                    logger.info(
-                        "Registration based on LDAP data was successful: %d: %s (%s, %)",
-                        user_id,
-                        localpart,
-                        name,
-                        mail
-                    )
-
-                    defer.returnValue(True)
-                else:
-                    if len(conn.response) == 0:
-                        logger.warn("LDAP registration failed, no result.")
-                    else:
-                        logger.warn(
-                            "LDAP registration failed, too many results (%s)",
-                            len(conn.response)
-                        )
-
-                    defer.returnValue(False)
-
-            defer.returnValue(False)
-
-        except ldap3.core.exceptions.LDAPException as e:
-            logger.warn("Error during ldap authentication: %s", e)
-            defer.returnValue(False)
-
     @defer.inlineCallbacks
     def issue_access_token(self, user_id, device_id=None):
         access_token = self.generate_access_token(user_id)
@@ -911,3 +659,30 @@ class AuthHandler(BaseHandler):
                                  stored_hash.encode('utf-8')) == stored_hash
         else:
             return False
+
+
+class _AccountHandler(object):
+    """A proxy object that gets passed to password auth providers so they
+    can register new users etc if necessary.
+    """
+    def __init__(self, hs, check_user_exists):
+        self.hs = hs
+
+        self._check_user_exists = check_user_exists
+
+    def check_user_exists(self, user_id):
+        """Check if user exissts.
+
+        Returns:
+            Deferred(bool)
+        """
+        return self._check_user_exists(user_id)
+
+    def register(self, localpart):
+        """Registers a new user with given localpart
+
+        Returns:
+            Deferred: a 2-tuple of (user_id, access_token)
+        """
+        reg = self.hs.get_handlers().registration_handler
+        return reg.register(localpart=localpart)
diff --git a/synapse/replication/resource.py b/synapse/replication/resource.py
index 9aab3ce23c..5a14c51d23 100644
--- a/synapse/replication/resource.py
+++ b/synapse/replication/resource.py
@@ -17,6 +17,7 @@ from synapse.http.servlet import parse_integer, parse_string
 from synapse.http.server import request_handler, finish_request
 from synapse.replication.pusher_resource import PusherResource
 from synapse.replication.presence_resource import PresenceResource
+from synapse.api.errors import SynapseError
 
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
@@ -166,7 +167,8 @@ class ReplicationResource(Resource):
         def replicate():
             return self.replicate(request_streams, limit)
 
-        result = yield self.notifier.wait_for_replication(replicate, timeout)
+        writer = yield self.notifier.wait_for_replication(replicate, timeout)
+        result = writer.finish()
 
         for stream_name, stream_content in result.items():
             logger.info(
@@ -186,6 +188,9 @@ class ReplicationResource(Resource):
         current_token = yield self.current_replication_token()
         logger.debug("Replicating up to %r", current_token)
 
+        if limit == 0:
+            raise SynapseError(400, "Limit cannot be 0")
+
         yield self.account_data(writer, current_token, limit, request_streams)
         yield self.events(writer, current_token, limit, request_streams)
         # TODO: implement limit
@@ -200,7 +205,7 @@ class ReplicationResource(Resource):
         self.streams(writer, current_token, request_streams)
 
         logger.debug("Replicated %d rows", writer.total)
-        defer.returnValue(writer.finish())
+        defer.returnValue(writer)
 
     def streams(self, writer, current_token, request_streams):
         request_token = request_streams.get("streams")
@@ -237,27 +242,48 @@ class ReplicationResource(Resource):
                 request_events = current_token.events
             if request_backfill is None:
                 request_backfill = current_token.backfill
+
+            no_new_tokens = (
+                request_events == current_token.events
+                and request_backfill == current_token.backfill
+            )
+            if no_new_tokens:
+                return
+
             res = yield self.store.get_all_new_events(
                 request_backfill, request_events,
                 current_token.backfill, current_token.events,
                 limit
             )
-            writer.write_header_and_rows("events", res.new_forward_events, (
-                "position", "internal", "json", "state_group"
-            ))
-            writer.write_header_and_rows("backfill", res.new_backfill_events, (
-                "position", "internal", "json", "state_group"
-            ))
+
+            upto_events_token = _position_from_rows(
+                res.new_forward_events, current_token.events
+            )
+
+            upto_backfill_token = _position_from_rows(
+                res.new_backfill_events, current_token.backfill
+            )
+
+            if request_events != upto_events_token:
+                writer.write_header_and_rows("events", res.new_forward_events, (
+                    "position", "internal", "json", "state_group"
+                ), position=upto_events_token)
+
+            if request_backfill != upto_backfill_token:
+                writer.write_header_and_rows("backfill", res.new_backfill_events, (
+                    "position", "internal", "json", "state_group",
+                ), position=upto_backfill_token)
+
             writer.write_header_and_rows(
                 "forward_ex_outliers", res.forward_ex_outliers,
-                ("position", "event_id", "state_group")
+                ("position", "event_id", "state_group"),
             )
             writer.write_header_and_rows(
                 "backward_ex_outliers", res.backward_ex_outliers,
-                ("position", "event_id", "state_group")
+                ("position", "event_id", "state_group"),
             )
             writer.write_header_and_rows(
-                "state_resets", res.state_resets, ("position",)
+                "state_resets", res.state_resets, ("position",),
             )
 
     @defer.inlineCallbacks
@@ -266,15 +292,16 @@ class ReplicationResource(Resource):
 
         request_presence = request_streams.get("presence")
 
-        if request_presence is not None:
+        if request_presence is not None and request_presence != current_position:
             presence_rows = yield self.presence_handler.get_all_presence_updates(
                 request_presence, current_position
             )
+            upto_token = _position_from_rows(presence_rows, current_position)
             writer.write_header_and_rows("presence", presence_rows, (
                 "position", "user_id", "state", "last_active_ts",
                 "last_federation_update_ts", "last_user_sync_ts",
                 "status_msg", "currently_active",
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def typing(self, writer, current_token, request_streams):
@@ -282,7 +309,7 @@ class ReplicationResource(Resource):
 
         request_typing = request_streams.get("typing")
 
-        if request_typing is not None:
+        if request_typing is not None and request_typing != current_position:
             # If they have a higher token than current max, we can assume that
             # they had been talking to a previous instance of the master. Since
             # we reset the token on restart, the best (but hacky) thing we can
@@ -293,9 +320,10 @@ class ReplicationResource(Resource):
             typing_rows = yield self.typing_handler.get_all_typing_updates(
                 request_typing, current_position
             )
+            upto_token = _position_from_rows(typing_rows, current_position)
             writer.write_header_and_rows("typing", typing_rows, (
                 "position", "room_id", "typing"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def receipts(self, writer, current_token, limit, request_streams):
@@ -303,13 +331,14 @@ class ReplicationResource(Resource):
 
         request_receipts = request_streams.get("receipts")
 
-        if request_receipts is not None:
+        if request_receipts is not None and request_receipts != current_position:
             receipts_rows = yield self.store.get_all_updated_receipts(
                 request_receipts, current_position, limit
             )
+            upto_token = _position_from_rows(receipts_rows, current_position)
             writer.write_header_and_rows("receipts", receipts_rows, (
                 "position", "room_id", "receipt_type", "user_id", "event_id", "data"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def account_data(self, writer, current_token, limit, request_streams):
@@ -324,23 +353,36 @@ class ReplicationResource(Resource):
                 user_account_data = current_position
             if room_account_data is None:
                 room_account_data = current_position
+
+            no_new_tokens = (
+                user_account_data == current_position
+                and room_account_data == current_position
+            )
+            if no_new_tokens:
+                return
+
             user_rows, room_rows = yield self.store.get_all_updated_account_data(
                 user_account_data, room_account_data, current_position, limit
             )
+
+            upto_users_token = _position_from_rows(user_rows, current_position)
+            upto_rooms_token = _position_from_rows(room_rows, current_position)
+
             writer.write_header_and_rows("user_account_data", user_rows, (
                 "position", "user_id", "type", "content"
-            ))
+            ), position=upto_users_token)
             writer.write_header_and_rows("room_account_data", room_rows, (
                 "position", "user_id", "room_id", "type", "content"
-            ))
+            ), position=upto_rooms_token)
 
         if tag_account_data is not None:
             tag_rows = yield self.store.get_all_updated_tags(
                 tag_account_data, current_position, limit
             )
+            upto_tag_token = _position_from_rows(tag_rows, current_position)
             writer.write_header_and_rows("tag_account_data", tag_rows, (
                 "position", "user_id", "room_id", "tags"
-            ))
+            ), position=upto_tag_token)
 
     @defer.inlineCallbacks
     def push_rules(self, writer, current_token, limit, request_streams):
@@ -348,14 +390,15 @@ class ReplicationResource(Resource):
 
         push_rules = request_streams.get("push_rules")
 
-        if push_rules is not None:
+        if push_rules is not None and push_rules != current_position:
             rows = yield self.store.get_all_push_rule_updates(
                 push_rules, current_position, limit
             )
+            upto_token = _position_from_rows(rows, current_position)
             writer.write_header_and_rows("push_rules", rows, (
                 "position", "event_stream_ordering", "user_id", "rule_id", "op",
                 "priority_class", "priority", "conditions", "actions"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def pushers(self, writer, current_token, limit, request_streams):
@@ -363,18 +406,19 @@ class ReplicationResource(Resource):
 
         pushers = request_streams.get("pushers")
 
-        if pushers is not None:
+        if pushers is not None and pushers != current_position:
             updated, deleted = yield self.store.get_all_updated_pushers(
                 pushers, current_position, limit
             )
+            upto_token = _position_from_rows(updated, current_position)
             writer.write_header_and_rows("pushers", updated, (
                 "position", "user_id", "access_token", "profile_tag", "kind",
                 "app_id", "app_display_name", "device_display_name", "pushkey",
                 "ts", "lang", "data"
-            ))
+            ), position=upto_token)
             writer.write_header_and_rows("deleted_pushers", deleted, (
                 "position", "user_id", "app_id", "pushkey"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def caches(self, writer, current_token, limit, request_streams):
@@ -382,13 +426,14 @@ class ReplicationResource(Resource):
 
         caches = request_streams.get("caches")
 
-        if caches is not None:
+        if caches is not None and caches != current_position:
             updated_caches = yield self.store.get_all_updated_caches(
                 caches, current_position, limit
             )
+            upto_token = _position_from_rows(updated_caches, current_position)
             writer.write_header_and_rows("caches", updated_caches, (
                 "position", "cache_func", "keys", "invalidation_ts"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def to_device(self, writer, current_token, limit, request_streams):
@@ -396,13 +441,14 @@ class ReplicationResource(Resource):
 
         to_device = request_streams.get("to_device")
 
-        if to_device is not None:
+        if to_device is not None and to_device != current_position:
             to_device_rows = yield self.store.get_all_new_device_messages(
                 to_device, current_position, limit
             )
+            upto_token = _position_from_rows(to_device_rows, current_position)
             writer.write_header_and_rows("to_device", to_device_rows, (
                 "position", "user_id", "device_id", "message_json"
-            ))
+            ), position=upto_token)
 
     @defer.inlineCallbacks
     def public_rooms(self, writer, current_token, limit, request_streams):
@@ -410,13 +456,14 @@ class ReplicationResource(Resource):
 
         public_rooms = request_streams.get("public_rooms")
 
-        if public_rooms is not None:
+        if public_rooms is not None and public_rooms != current_position:
             public_rooms_rows = yield self.store.get_all_new_public_rooms(
                 public_rooms, current_position, limit
             )
+            upto_token = _position_from_rows(public_rooms_rows, current_position)
             writer.write_header_and_rows("public_rooms", public_rooms_rows, (
                 "position", "room_id", "visibility"
-            ))
+            ), position=upto_token)
 
 
 class _Writer(object):
@@ -426,11 +473,11 @@ class _Writer(object):
         self.total = 0
 
     def write_header_and_rows(self, name, rows, fields, position=None):
-        if not rows:
-            return
-
         if position is None:
-            position = rows[-1][0]
+            if rows:
+                position = rows[-1][0]
+            else:
+                return
 
         self.streams[name] = {
             "position": position if type(position) is int else str(position),
@@ -440,6 +487,9 @@ class _Writer(object):
 
         self.total += len(rows)
 
+    def __nonzero__(self):
+        return bool(self.total)
+
     def finish(self):
         return self.streams
 
@@ -461,3 +511,20 @@ class _ReplicationToken(collections.namedtuple("_ReplicationToken", (
 
     def __str__(self):
         return "_".join(str(value) for value in self)
+
+
+def _position_from_rows(rows, current_position):
+    """Calculates a position to return for a stream. Ideally we want to return the
+    position of the last row, as that will be the most correct. However, if there
+    are no rows we fall back to using the current position to stop us from
+    repeatedly hitting the storage layer unncessarily thinking there are updates.
+    (Not all advances of the token correspond to an actual update)
+
+    We can't just always return the current position, as we often limit the
+    number of rows we replicate, and so the stream may lag. The assumption is
+    that if the storage layer returns no new rows then we are not lagging and
+    we are at the `current_position`.
+    """
+    if rows:
+        return rows[-1][0]
+    return current_position
diff --git a/synapse/rest/client/v2_alpha/auth.py b/synapse/rest/client/v2_alpha/auth.py
index 58d3cad6a1..8e5577148f 100644
--- a/synapse/rest/client/v2_alpha/auth.py
+++ b/synapse/rest/client/v2_alpha/auth.py
@@ -77,8 +77,10 @@ SUCCESS_TEMPLATE = """
     user-scalable=no, minimum-scale=1.0, maximum-scale=1.0'>
 <link rel="stylesheet" href="/_matrix/static/client/register/style.css">
 <script>
-if (window.onAuthDone != undefined) {
+if (window.onAuthDone) {
     window.onAuthDone();
+} else if (window.opener && window.opener.postMessage) {
+     window.opener.postMessage("authDone", "*");
 }
 </script>
 </head>
diff --git a/synapse/rest/client/v2_alpha/devices.py b/synapse/rest/client/v2_alpha/devices.py
index 8fbd3d3dfc..3ba0b0fc07 100644
--- a/synapse/rest/client/v2_alpha/devices.py
+++ b/synapse/rest/client/v2_alpha/devices.py
@@ -17,6 +17,7 @@ import logging
 
 from twisted.internet import defer
 
+from synapse.api import constants, errors
 from synapse.http import servlet
 from ._base import client_v2_patterns
 
@@ -58,6 +59,7 @@ class DeviceRestServlet(servlet.RestServlet):
         self.hs = hs
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
+        self.auth_handler = hs.get_auth_handler()
 
     @defer.inlineCallbacks
     def on_GET(self, request, device_id):
@@ -70,11 +72,24 @@ class DeviceRestServlet(servlet.RestServlet):
 
     @defer.inlineCallbacks
     def on_DELETE(self, request, device_id):
-        # XXX: it's not completely obvious we want to expose this endpoint.
-        # It allows the client to delete access tokens, which feels like a
-        # thing which merits extra auth. But if we want to do the interactive-
-        # auth dance, we should really make it possible to delete more than one
-        # device at a time.
+        try:
+            body = servlet.parse_json_object_from_request(request)
+
+        except errors.SynapseError as e:
+            if e.errcode == errors.Codes.NOT_JSON:
+                # deal with older clients which didn't pass a JSON dict
+                # the same as those that pass an empty dict
+                body = {}
+            else:
+                raise
+
+        authed, result, params, _ = yield self.auth_handler.check_auth([
+            [constants.LoginType.PASSWORD],
+        ], body, self.hs.get_ip_from_request(request))
+
+        if not authed:
+            defer.returnValue((401, result))
+
         requester = yield self.auth.get_user_by_req(request)
         yield self.device_handler.delete_device(
             requester.user.to_string(),
diff --git a/synapse/rest/key/v2/local_key_resource.py b/synapse/rest/key/v2/local_key_resource.py
index 93e5b1cbf0..ff95269ba8 100644
--- a/synapse/rest/key/v2/local_key_resource.py
+++ b/synapse/rest/key/v2/local_key_resource.py
@@ -19,8 +19,6 @@ from synapse.http.server import respond_with_json_bytes
 from signedjson.sign import sign_json
 from unpaddedbase64 import encode_base64
 from canonicaljson import encode_canonical_json
-from hashlib import sha256
-from OpenSSL import crypto
 import logging
 
 
@@ -48,8 +46,12 @@ class LocalKey(Resource):
                     "expired_ts": # integer posix timestamp when the key expired.
                     "key": # base64 encoded NACL verification key.
                 }
-            }
-            "tls_certificate": # base64 ASN.1 DER encoded X.509 tls cert.
+            },
+            "tls_fingerprints": [ # Fingerprints of the TLS certs this server uses.
+                {
+                    "sha256": # base64 encoded sha256 fingerprint of the X509 cert
+                },
+            ],
             "signatures": {
                 "this.server.example.com": {
                    "algorithm:version": # NACL signature for this server
@@ -90,21 +92,14 @@ class LocalKey(Resource):
                 u"expired_ts": key.expired,
             }
 
-        x509_certificate_bytes = crypto.dump_certificate(
-            crypto.FILETYPE_ASN1,
-            self.config.tls_certificate
-        )
-
-        sha256_fingerprint = sha256(x509_certificate_bytes).digest()
+        tls_fingerprints = self.config.tls_fingerprints
 
         json_object = {
             u"valid_until_ts": self.valid_until_ts,
             u"server_name": self.config.server_name,
             u"verify_keys": verify_keys,
             u"old_verify_keys": old_verify_keys,
-            u"tls_fingerprints": [{
-                u"sha256": encode_base64(sha256_fingerprint),
-            }]
+            u"tls_fingerprints": tls_fingerprints,
         }
         for key in self.config.signing_key:
             json_object = sign_json(
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index 2ef13d7403..11813b44f6 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -320,6 +320,9 @@ class RoomStore(SQLBaseStore):
             txn.execute(sql, (prev_id, current_id, limit,))
             return txn.fetchall()
 
+        if prev_id == current_id:
+            return defer.succeed([])
+
         return self.runInteraction(
             "get_all_new_public_rooms", get_all_new_public_rooms
         )
diff --git a/synapse/util/ldap_auth_provider.py b/synapse/util/ldap_auth_provider.py
new file mode 100644
index 0000000000..f852e9b037
--- /dev/null
+++ b/synapse/util/ldap_auth_provider.py
@@ -0,0 +1,368 @@
+
+from twisted.internet import defer
+
+from synapse.config._base import ConfigError
+from synapse.types import UserID
+
+import ldap3
+import ldap3.core.exceptions
+
+import logging
+
+try:
+    import ldap3
+    import ldap3.core.exceptions
+except ImportError:
+    ldap3 = None
+    pass
+
+
+logger = logging.getLogger(__name__)
+
+
+class LDAPMode(object):
+    SIMPLE = "simple",
+    SEARCH = "search",
+
+    LIST = (SIMPLE, SEARCH)
+
+
+class LdapAuthProvider(object):
+    __version__ = "0.1"
+
+    def __init__(self, config, account_handler):
+        self.account_handler = account_handler
+
+        if not ldap3:
+            raise RuntimeError(
+                'Missing ldap3 library. This is required for LDAP Authentication.'
+            )
+
+        self.ldap_mode = config.mode
+        self.ldap_uri = config.uri
+        self.ldap_start_tls = config.start_tls
+        self.ldap_base = config.base
+        self.ldap_attributes = config.attributes
+        if self.ldap_mode == LDAPMode.SEARCH:
+            self.ldap_bind_dn = config.bind_dn
+            self.ldap_bind_password = config.bind_password
+            self.ldap_filter = config.filter
+
+    @defer.inlineCallbacks
+    def check_password(self, user_id, password):
+        """ Attempt to authenticate a user against an LDAP Server
+            and register an account if none exists.
+
+            Returns:
+                True if authentication against LDAP was successful
+        """
+        localpart = UserID.from_string(user_id).localpart
+
+        try:
+            server = ldap3.Server(self.ldap_uri)
+            logger.debug(
+                "Attempting LDAP connection with %s",
+                self.ldap_uri
+            )
+
+            if self.ldap_mode == LDAPMode.SIMPLE:
+                result, conn = self._ldap_simple_bind(
+                    server=server, localpart=localpart, password=password
+                )
+                logger.debug(
+                    'LDAP authentication method simple bind returned: %s (conn: %s)',
+                    result,
+                    conn
+                )
+                if not result:
+                    defer.returnValue(False)
+            elif self.ldap_mode == LDAPMode.SEARCH:
+                result, conn = self._ldap_authenticated_search(
+                    server=server, localpart=localpart, password=password
+                )
+                logger.debug(
+                    'LDAP auth method authenticated search returned: %s (conn: %s)',
+                    result,
+                    conn
+                )
+                if not result:
+                    defer.returnValue(False)
+            else:
+                raise RuntimeError(
+                    'Invalid LDAP mode specified: {mode}'.format(
+                        mode=self.ldap_mode
+                    )
+                )
+
+            try:
+                logger.info(
+                    "User authenticated against LDAP server: %s",
+                    conn
+                )
+            except NameError:
+                logger.warn(
+                    "Authentication method yielded no LDAP connection, aborting!"
+                )
+                defer.returnValue(False)
+
+            # check if user with user_id exists
+            if (yield self.account_handler.check_user_exists(user_id)):
+                # exists, authentication complete
+                conn.unbind()
+                defer.returnValue(True)
+
+            else:
+                # does not exist, fetch metadata for account creation from
+                # existing ldap connection
+                query = "({prop}={value})".format(
+                    prop=self.ldap_attributes['uid'],
+                    value=localpart
+                )
+
+                if self.ldap_mode == LDAPMode.SEARCH and self.ldap_filter:
+                    query = "(&{filter}{user_filter})".format(
+                        filter=query,
+                        user_filter=self.ldap_filter
+                    )
+                logger.debug(
+                    "ldap registration filter: %s",
+                    query
+                )
+
+                conn.search(
+                    search_base=self.ldap_base,
+                    search_filter=query,
+                    attributes=[
+                        self.ldap_attributes['name'],
+                        self.ldap_attributes['mail']
+                    ]
+                )
+
+                if len(conn.response) == 1:
+                    attrs = conn.response[0]['attributes']
+                    mail = attrs[self.ldap_attributes['mail']][0]
+                    name = attrs[self.ldap_attributes['name']][0]
+
+                    # create account
+                    user_id, access_token = (
+                        yield self.account_handler.register(localpart=localpart)
+                    )
+
+                    # TODO: bind email, set displayname with data from ldap directory
+
+                    logger.info(
+                        "Registration based on LDAP data was successful: %d: %s (%s, %)",
+                        user_id,
+                        localpart,
+                        name,
+                        mail
+                    )
+
+                    defer.returnValue(True)
+                else:
+                    if len(conn.response) == 0:
+                        logger.warn("LDAP registration failed, no result.")
+                    else:
+                        logger.warn(
+                            "LDAP registration failed, too many results (%s)",
+                            len(conn.response)
+                        )
+
+                    defer.returnValue(False)
+
+            defer.returnValue(False)
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during ldap authentication: %s", e)
+            defer.returnValue(False)
+
+    @staticmethod
+    def parse_config(config):
+        class _LdapConfig(object):
+            pass
+
+        ldap_config = _LdapConfig()
+
+        ldap_config.enabled = config.get("enabled", False)
+
+        ldap_config.mode = LDAPMode.SIMPLE
+
+        # verify config sanity
+        _require_keys(config, [
+            "uri",
+            "base",
+            "attributes",
+        ])
+
+        ldap_config.uri = config["uri"]
+        ldap_config.start_tls = config.get("start_tls", False)
+        ldap_config.base = config["base"]
+        ldap_config.attributes = config["attributes"]
+
+        if "bind_dn" in config:
+            ldap_config.mode = LDAPMode.SEARCH
+            _require_keys(config, [
+                "bind_dn",
+                "bind_password",
+            ])
+
+            ldap_config.bind_dn = config["bind_dn"]
+            ldap_config.bind_password = config["bind_password"]
+            ldap_config.filter = config.get("filter", None)
+
+        # verify attribute lookup
+        _require_keys(config['attributes'], [
+            "uid",
+            "name",
+            "mail",
+        ])
+
+        return ldap_config
+
+    def _ldap_simple_bind(self, server, localpart, password):
+        """ Attempt a simple bind with the credentials
+            given by the user against the LDAP server.
+
+            Returns True, LDAP3Connection
+                if the bind was successful
+            Returns False, None
+                if an error occured
+        """
+
+        try:
+            # bind with the the local users ldap credentials
+            bind_dn = "{prop}={value},{base}".format(
+                prop=self.ldap_attributes['uid'],
+                value=localpart,
+                base=self.ldap_base
+            )
+            conn = ldap3.Connection(server, bind_dn, password)
+            logger.debug(
+                "Established LDAP connection in simple bind mode: %s",
+                conn
+            )
+
+            if self.ldap_start_tls:
+                conn.start_tls()
+                logger.debug(
+                    "Upgraded LDAP connection in simple bind mode through StartTLS: %s",
+                    conn
+                )
+
+            if conn.bind():
+                # GOOD: bind okay
+                logger.debug("LDAP Bind successful in simple bind mode.")
+                return True, conn
+
+            # BAD: bind failed
+            logger.info(
+                "Binding against LDAP failed for '%s' failed: %s",
+                localpart, conn.result['description']
+            )
+            conn.unbind()
+            return False, None
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during LDAP authentication: %s", e)
+            return False, None
+
+    def _ldap_authenticated_search(self, server, localpart, password):
+        """ Attempt to login with the preconfigured bind_dn
+            and then continue searching and filtering within
+            the base_dn
+
+            Returns (True, LDAP3Connection)
+                if a single matching DN within the base was found
+                that matched the filter expression, and with which
+                a successful bind was achieved
+
+                The LDAP3Connection returned is the instance that was used to
+                verify the password not the one using the configured bind_dn.
+            Returns (False, None)
+                if an error occured
+        """
+
+        try:
+            conn = ldap3.Connection(
+                server,
+                self.ldap_bind_dn,
+                self.ldap_bind_password
+            )
+            logger.debug(
+                "Established LDAP connection in search mode: %s",
+                conn
+            )
+
+            if self.ldap_start_tls:
+                conn.start_tls()
+                logger.debug(
+                    "Upgraded LDAP connection in search mode through StartTLS: %s",
+                    conn
+                )
+
+            if not conn.bind():
+                logger.warn(
+                    "Binding against LDAP with `bind_dn` failed: %s",
+                    conn.result['description']
+                )
+                conn.unbind()
+                return False, None
+
+            # construct search_filter like (uid=localpart)
+            query = "({prop}={value})".format(
+                prop=self.ldap_attributes['uid'],
+                value=localpart
+            )
+            if self.ldap_filter:
+                # combine with the AND expression
+                query = "(&{query}{filter})".format(
+                    query=query,
+                    filter=self.ldap_filter
+                )
+            logger.debug(
+                "LDAP search filter: %s",
+                query
+            )
+            conn.search(
+                search_base=self.ldap_base,
+                search_filter=query
+            )
+
+            if len(conn.response) == 1:
+                # GOOD: found exactly one result
+                user_dn = conn.response[0]['dn']
+                logger.debug('LDAP search found dn: %s', user_dn)
+
+                # unbind and simple bind with user_dn to verify the password
+                # Note: do not use rebind(), for some reason it did not verify
+                #       the password for me!
+                conn.unbind()
+                return self._ldap_simple_bind(server, localpart, password)
+            else:
+                # BAD: found 0 or > 1 results, abort!
+                if len(conn.response) == 0:
+                    logger.info(
+                        "LDAP search returned no results for '%s'",
+                        localpart
+                    )
+                else:
+                    logger.info(
+                        "LDAP search returned too many (%s) results for '%s'",
+                        len(conn.response), localpart
+                    )
+                conn.unbind()
+                return False, None
+
+        except ldap3.core.exceptions.LDAPException as e:
+            logger.warn("Error during LDAP authentication: %s", e)
+            return False, None
+
+
+def _require_keys(config, required):
+    missing = [key for key in required if key not in config]
+    if missing:
+        raise ConfigError(
+            "LDAP enabled but missing required config values: {}".format(
+                ", ".join(missing)
+            )
+        )