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-rw-r--r--synapse/rest/client/v1/login.py88
-rw-r--r--synapse/rest/client/v2_alpha/account.py114
-rw-r--r--synapse/rest/client/v2_alpha/register.py137
-rw-r--r--synapse/rest/media/v1/download_resource.py12
-rw-r--r--synapse/rest/media/v1/media_repository.py44
5 files changed, 343 insertions, 52 deletions
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index 34eebe6fd8..a43410fb37 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -19,6 +19,7 @@ from synapse.api.errors import SynapseError, LoginError, Codes
 from synapse.types import UserID
 from synapse.http.server import finish_request
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.util.msisdn import phone_number_to_msisdn
 
 from .base import ClientV1RestServlet, client_path_patterns
 
@@ -39,6 +40,49 @@ from twisted.web.client import PartialDownloadError
 logger = logging.getLogger(__name__)
 
 
+def login_submission_legacy_convert(submission):
+    """
+    If the input login submission is an old style object
+    (ie. with top-level user / medium / address) convert it
+    to a typed object.
+    """
+    if "user" in submission:
+        submission["identifier"] = {
+            "type": "m.id.user",
+            "user": submission["user"],
+        }
+        del submission["user"]
+
+    if "medium" in submission and "address" in submission:
+        submission["identifier"] = {
+            "type": "m.id.thirdparty",
+            "medium": submission["medium"],
+            "address": submission["address"],
+        }
+        del submission["medium"]
+        del submission["address"]
+
+
+def login_id_thirdparty_from_phone(identifier):
+    """
+    Convert a phone login identifier type to a generic threepid identifier
+    Args:
+        identifier(dict): Login identifier dict of type 'm.id.phone'
+
+    Returns: Login identifier dict of type 'm.id.threepid'
+    """
+    if "country" not in identifier or "number" not in identifier:
+        raise SynapseError(400, "Invalid phone-type identifier")
+
+    msisdn = phone_number_to_msisdn(identifier["country"], identifier["number"])
+
+    return {
+        "type": "m.id.thirdparty",
+        "medium": "msisdn",
+        "address": msisdn,
+    }
+
+
 class LoginRestServlet(ClientV1RestServlet):
     PATTERNS = client_path_patterns("/login$")
     PASS_TYPE = "m.login.password"
@@ -119,20 +163,52 @@ class LoginRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def do_password_login(self, login_submission):
-        if 'medium' in login_submission and 'address' in login_submission:
-            address = login_submission['address']
-            if login_submission['medium'] == 'email':
+        if "password" not in login_submission:
+            raise SynapseError(400, "Missing parameter: password")
+
+        login_submission_legacy_convert(login_submission)
+
+        if "identifier" not in login_submission:
+            raise SynapseError(400, "Missing param: identifier")
+
+        identifier = login_submission["identifier"]
+        if "type" not in identifier:
+            raise SynapseError(400, "Login identifier has no type")
+
+        # convert phone type identifiers to generic threepids
+        if identifier["type"] == "m.id.phone":
+            identifier = login_id_thirdparty_from_phone(identifier)
+
+        # convert threepid identifiers to user IDs
+        if identifier["type"] == "m.id.thirdparty":
+            if 'medium' not in identifier or 'address' not in identifier:
+                raise SynapseError(400, "Invalid thirdparty identifier")
+
+            address = identifier['address']
+            if identifier['medium'] == 'email':
                 # For emails, transform the address to lowercase.
                 # We store all email addreses as lowercase in the DB.
                 # (See add_threepid in synapse/handlers/auth.py)
                 address = address.lower()
             user_id = yield self.hs.get_datastore().get_user_id_by_threepid(
-                login_submission['medium'], address
+                identifier['medium'], address
             )
             if not user_id:
                 raise LoginError(403, "", errcode=Codes.FORBIDDEN)
-        else:
-            user_id = login_submission['user']
+
+            identifier = {
+                "type": "m.id.user",
+                "user": user_id,
+            }
+
+        # by this point, the identifier should be an m.id.user: if it's anything
+        # else, we haven't understood it.
+        if identifier["type"] != "m.id.user":
+            raise SynapseError(400, "Unknown login identifier type")
+        if "user" not in identifier:
+            raise SynapseError(400, "User identifier is missing 'user' key")
+
+        user_id = identifier["user"]
 
         if not user_id.startswith('@'):
             user_id = UserID.create(
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 398e7f5eb0..aac76edf1c 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2017 Vector Creations Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -17,8 +18,11 @@ from twisted.internet import defer
 
 from synapse.api.constants import LoginType
 from synapse.api.errors import LoginError, SynapseError, Codes
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.servlet import (
+    RestServlet, parse_json_object_from_request, assert_params_in_request
+)
 from synapse.util.async import run_on_reactor
+from synapse.util.msisdn import phone_number_to_msisdn
 
 from ._base import client_v2_patterns
 
@@ -28,11 +32,11 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-class PasswordRequestTokenRestServlet(RestServlet):
+class EmailPasswordRequestTokenRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/account/password/email/requestToken$")
 
     def __init__(self, hs):
-        super(PasswordRequestTokenRestServlet, self).__init__()
+        super(EmailPasswordRequestTokenRestServlet, self).__init__()
         self.hs = hs
         self.identity_handler = hs.get_handlers().identity_handler
 
@@ -40,14 +44,9 @@ class PasswordRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        required = ['id_server', 'client_secret', 'email', 'send_attempt']
-        absent = []
-        for k in required:
-            if k not in body:
-                absent.append(k)
-
-        if absent:
-            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+        assert_params_in_request(body, [
+            'id_server', 'client_secret', 'email', 'send_attempt'
+        ])
 
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
             'email', body['email']
@@ -60,6 +59,37 @@ class PasswordRequestTokenRestServlet(RestServlet):
         defer.returnValue((200, ret))
 
 
+class MsisdnPasswordRequestTokenRestServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/account/password/msisdn/requestToken$")
+
+    def __init__(self, hs):
+        super(MsisdnPasswordRequestTokenRestServlet, self).__init__()
+        self.hs = hs
+        self.datastore = self.hs.get_datastore()
+        self.identity_handler = hs.get_handlers().identity_handler
+
+    @defer.inlineCallbacks
+    def on_POST(self, request):
+        body = parse_json_object_from_request(request)
+
+        assert_params_in_request(body, [
+            'id_server', 'client_secret',
+            'country', 'phone_number', 'send_attempt',
+        ])
+
+        msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
+
+        existingUid = yield self.datastore.get_user_id_by_threepid(
+            'msisdn', msisdn
+        )
+
+        if existingUid is None:
+            raise SynapseError(400, "MSISDN not found", Codes.THREEPID_NOT_FOUND)
+
+        ret = yield self.identity_handler.requestMsisdnToken(**body)
+        defer.returnValue((200, ret))
+
+
 class PasswordRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/account/password$")
 
@@ -68,6 +98,7 @@ class PasswordRestServlet(RestServlet):
         self.hs = hs
         self.auth = hs.get_auth()
         self.auth_handler = hs.get_auth_handler()
+        self.datastore = self.hs.get_datastore()
 
     @defer.inlineCallbacks
     def on_POST(self, request):
@@ -77,7 +108,8 @@ class PasswordRestServlet(RestServlet):
 
         authed, result, params, _ = yield self.auth_handler.check_auth([
             [LoginType.PASSWORD],
-            [LoginType.EMAIL_IDENTITY]
+            [LoginType.EMAIL_IDENTITY],
+            [LoginType.MSISDN],
         ], body, self.hs.get_ip_from_request(request))
 
         if not authed:
@@ -102,7 +134,7 @@ class PasswordRestServlet(RestServlet):
                 # (See add_threepid in synapse/handlers/auth.py)
                 threepid['address'] = threepid['address'].lower()
             # if using email, we must know about the email they're authing with!
-            threepid_user_id = yield self.hs.get_datastore().get_user_id_by_threepid(
+            threepid_user_id = yield self.datastore.get_user_id_by_threepid(
                 threepid['medium'], threepid['address']
             )
             if not threepid_user_id:
@@ -169,13 +201,14 @@ class DeactivateAccountRestServlet(RestServlet):
         defer.returnValue((200, {}))
 
 
-class ThreepidRequestTokenRestServlet(RestServlet):
+class EmailThreepidRequestTokenRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/account/3pid/email/requestToken$")
 
     def __init__(self, hs):
         self.hs = hs
-        super(ThreepidRequestTokenRestServlet, self).__init__()
+        super(EmailThreepidRequestTokenRestServlet, self).__init__()
         self.identity_handler = hs.get_handlers().identity_handler
+        self.datastore = self.hs.get_datastore()
 
     @defer.inlineCallbacks
     def on_POST(self, request):
@@ -190,7 +223,7 @@ class ThreepidRequestTokenRestServlet(RestServlet):
         if absent:
             raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
 
-        existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
+        existingUid = yield self.datastore.get_user_id_by_threepid(
             'email', body['email']
         )
 
@@ -201,6 +234,44 @@ class ThreepidRequestTokenRestServlet(RestServlet):
         defer.returnValue((200, ret))
 
 
+class MsisdnThreepidRequestTokenRestServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/account/3pid/msisdn/requestToken$")
+
+    def __init__(self, hs):
+        self.hs = hs
+        super(MsisdnThreepidRequestTokenRestServlet, self).__init__()
+        self.identity_handler = hs.get_handlers().identity_handler
+        self.datastore = self.hs.get_datastore()
+
+    @defer.inlineCallbacks
+    def on_POST(self, request):
+        body = parse_json_object_from_request(request)
+
+        required = [
+            'id_server', 'client_secret',
+            'country', 'phone_number', 'send_attempt',
+        ]
+        absent = []
+        for k in required:
+            if k not in body:
+                absent.append(k)
+
+        if absent:
+            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+
+        msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
+
+        existingUid = yield self.datastore.get_user_id_by_threepid(
+            'msisdn', msisdn
+        )
+
+        if existingUid is not None:
+            raise SynapseError(400, "MSISDN is already in use", Codes.THREEPID_IN_USE)
+
+        ret = yield self.identity_handler.requestEmailToken(**body)
+        defer.returnValue((200, ret))
+
+
 class ThreepidRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/account/3pid$")
 
@@ -210,6 +281,7 @@ class ThreepidRestServlet(RestServlet):
         self.identity_handler = hs.get_handlers().identity_handler
         self.auth = hs.get_auth()
         self.auth_handler = hs.get_auth_handler()
+        self.datastore = self.hs.get_datastore()
 
     @defer.inlineCallbacks
     def on_GET(self, request):
@@ -217,7 +289,7 @@ class ThreepidRestServlet(RestServlet):
 
         requester = yield self.auth.get_user_by_req(request)
 
-        threepids = yield self.hs.get_datastore().user_get_threepids(
+        threepids = yield self.datastore.user_get_threepids(
             requester.user.to_string()
         )
 
@@ -258,7 +330,7 @@ class ThreepidRestServlet(RestServlet):
 
         if 'bind' in body and body['bind']:
             logger.debug(
-                "Binding emails %s to %s",
+                "Binding threepid %s to %s",
                 threepid, user_id
             )
             yield self.identity_handler.bind_threepid(
@@ -302,9 +374,11 @@ class ThreepidDeleteRestServlet(RestServlet):
 
 
 def register_servlets(hs, http_server):
-    PasswordRequestTokenRestServlet(hs).register(http_server)
+    EmailPasswordRequestTokenRestServlet(hs).register(http_server)
+    MsisdnPasswordRequestTokenRestServlet(hs).register(http_server)
     PasswordRestServlet(hs).register(http_server)
     DeactivateAccountRestServlet(hs).register(http_server)
-    ThreepidRequestTokenRestServlet(hs).register(http_server)
+    EmailThreepidRequestTokenRestServlet(hs).register(http_server)
+    MsisdnThreepidRequestTokenRestServlet(hs).register(http_server)
     ThreepidRestServlet(hs).register(http_server)
     ThreepidDeleteRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index ccca5a12d5..dcd13b876f 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2015 - 2016 OpenMarket Ltd
+# Copyright 2017 Vector Creations Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -19,7 +20,10 @@ import synapse
 from synapse.api.auth import get_access_token_from_request, has_access_token
 from synapse.api.constants import LoginType
 from synapse.api.errors import SynapseError, Codes, UnrecognizedRequestError
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.servlet import (
+    RestServlet, parse_json_object_from_request, assert_params_in_request
+)
+from synapse.util.msisdn import phone_number_to_msisdn
 
 from ._base import client_v2_patterns
 
@@ -43,7 +47,7 @@ else:
 logger = logging.getLogger(__name__)
 
 
-class RegisterRequestTokenRestServlet(RestServlet):
+class EmailRegisterRequestTokenRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/register/email/requestToken$")
 
     def __init__(self, hs):
@@ -51,7 +55,7 @@ class RegisterRequestTokenRestServlet(RestServlet):
         Args:
             hs (synapse.server.HomeServer): server
         """
-        super(RegisterRequestTokenRestServlet, self).__init__()
+        super(EmailRegisterRequestTokenRestServlet, self).__init__()
         self.hs = hs
         self.identity_handler = hs.get_handlers().identity_handler
 
@@ -59,14 +63,9 @@ class RegisterRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        required = ['id_server', 'client_secret', 'email', 'send_attempt']
-        absent = []
-        for k in required:
-            if k not in body:
-                absent.append(k)
-
-        if len(absent) > 0:
-            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+        assert_params_in_request(body, [
+            'id_server', 'client_secret', 'email', 'send_attempt'
+        ])
 
         existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
             'email', body['email']
@@ -79,6 +78,43 @@ class RegisterRequestTokenRestServlet(RestServlet):
         defer.returnValue((200, ret))
 
 
+class MsisdnRegisterRequestTokenRestServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/register/msisdn/requestToken$")
+
+    def __init__(self, hs):
+        """
+        Args:
+            hs (synapse.server.HomeServer): server
+        """
+        super(MsisdnRegisterRequestTokenRestServlet, self).__init__()
+        self.hs = hs
+        self.identity_handler = hs.get_handlers().identity_handler
+
+    @defer.inlineCallbacks
+    def on_POST(self, request):
+        body = parse_json_object_from_request(request)
+
+        assert_params_in_request(body, [
+            'id_server', 'client_secret',
+            'country', 'phone_number',
+            'send_attempt',
+        ])
+
+        msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
+
+        existingUid = yield self.hs.get_datastore().get_user_id_by_threepid(
+            'msisdn', msisdn
+        )
+
+        if existingUid is not None:
+            raise SynapseError(
+                400, "Phone number is already in use", Codes.THREEPID_IN_USE
+            )
+
+        ret = yield self.identity_handler.requestMsisdnToken(**body)
+        defer.returnValue((200, ret))
+
+
 class RegisterRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/register$")
 
@@ -200,16 +236,37 @@ class RegisterRestServlet(RestServlet):
                 assigned_user_id=registered_user_id,
             )
 
+        # Only give msisdn flows if the x_show_msisdn flag is given:
+        # this is a hack to work around the fact that clients were shipped
+        # that use fallback registration if they see any flows that they don't
+        # recognise, which means we break registration for these clients if we
+        # advertise msisdn flows. Once usage of Riot iOS <=0.3.9 and Riot
+        # Android <=0.6.9 have fallen below an acceptable threshold, this
+        # parameter should go away and we should always advertise msisdn flows.
+        show_msisdn = False
+        if 'x_show_msisdn' in body and body['x_show_msisdn']:
+            show_msisdn = True
+
         if self.hs.config.enable_registration_captcha:
             flows = [
                 [LoginType.RECAPTCHA],
-                [LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA]
+                [LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA],
             ]
+            if show_msisdn:
+                flows.extend([
+                    [LoginType.MSISDN, LoginType.RECAPTCHA],
+                    [LoginType.MSISDN, LoginType.EMAIL_IDENTITY, LoginType.RECAPTCHA],
+                ])
         else:
             flows = [
                 [LoginType.DUMMY],
-                [LoginType.EMAIL_IDENTITY]
+                [LoginType.EMAIL_IDENTITY],
             ]
+            if show_msisdn:
+                flows.extend([
+                    [LoginType.MSISDN],
+                    [LoginType.MSISDN, LoginType.EMAIL_IDENTITY],
+                ])
 
         authed, auth_result, params, session_id = yield self.auth_handler.check_auth(
             flows, body, self.hs.get_ip_from_request(request)
@@ -224,8 +281,9 @@ class RegisterRestServlet(RestServlet):
                 "Already registered user ID %r for this session",
                 registered_user_id
             )
-            # don't re-register the email address
+            # don't re-register the threepids
             add_email = False
+            add_msisdn = False
         else:
             # NB: This may be from the auth handler and NOT from the POST
             if 'password' not in params:
@@ -250,6 +308,7 @@ class RegisterRestServlet(RestServlet):
             )
 
             add_email = True
+            add_msisdn = True
 
         return_dict = yield self._create_registration_details(
             registered_user_id, params
@@ -262,6 +321,13 @@ class RegisterRestServlet(RestServlet):
                 params.get("bind_email")
             )
 
+        if add_msisdn and auth_result and LoginType.MSISDN in auth_result:
+            threepid = auth_result[LoginType.MSISDN]
+            yield self._register_msisdn_threepid(
+                registered_user_id, threepid, return_dict["access_token"],
+                params.get("bind_msisdn")
+            )
+
         defer.returnValue((200, return_dict))
 
     def on_OPTIONS(self, _):
@@ -323,8 +389,9 @@ class RegisterRestServlet(RestServlet):
         """
         reqd = ('medium', 'address', 'validated_at')
         if any(x not in threepid for x in reqd):
+            # This will only happen if the ID server returns a malformed response
             logger.info("Can't add incomplete 3pid")
-            defer.returnValue()
+            return
 
         yield self.auth_handler.add_threepid(
             user_id,
@@ -372,6 +439,43 @@ class RegisterRestServlet(RestServlet):
             logger.info("bind_email not specified: not binding email")
 
     @defer.inlineCallbacks
+    def _register_msisdn_threepid(self, user_id, threepid, token, bind_msisdn):
+        """Add a phone number as a 3pid identifier
+
+        Also optionally binds msisdn to the given user_id on the identity server
+
+        Args:
+            user_id (str): id of user
+            threepid (object): m.login.msisdn auth response
+            token (str): access_token for the user
+            bind_email (bool): true if the client requested the email to be
+                bound at the identity server
+        Returns:
+            defer.Deferred:
+        """
+        reqd = ('medium', 'address', 'validated_at')
+        if any(x not in threepid for x in reqd):
+            # This will only happen if the ID server returns a malformed response
+            logger.info("Can't add incomplete 3pid")
+            defer.returnValue()
+
+        yield self.auth_handler.add_threepid(
+            user_id,
+            threepid['medium'],
+            threepid['address'],
+            threepid['validated_at'],
+        )
+
+        if bind_msisdn:
+            logger.info("bind_msisdn specified: binding")
+            logger.debug("Binding msisdn %s to %s", threepid, user_id)
+            yield self.identity_handler.bind_threepid(
+                threepid['threepid_creds'], user_id
+            )
+        else:
+            logger.info("bind_msisdn not specified: not binding msisdn")
+
+    @defer.inlineCallbacks
     def _create_registration_details(self, user_id, params):
         """Complete registration of newly-registered user
 
@@ -449,5 +553,6 @@ class RegisterRestServlet(RestServlet):
 
 
 def register_servlets(hs, http_server):
-    RegisterRequestTokenRestServlet(hs).register(http_server)
+    EmailRegisterRequestTokenRestServlet(hs).register(http_server)
+    MsisdnRegisterRequestTokenRestServlet(hs).register(http_server)
     RegisterRestServlet(hs).register(http_server)
diff --git a/synapse/rest/media/v1/download_resource.py b/synapse/rest/media/v1/download_resource.py
index dfb87ffd15..6788375e85 100644
--- a/synapse/rest/media/v1/download_resource.py
+++ b/synapse/rest/media/v1/download_resource.py
@@ -12,6 +12,7 @@
 # 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.
+import synapse.http.servlet
 
 from ._base import parse_media_id, respond_with_file, respond_404
 from twisted.web.resource import Resource
@@ -81,6 +82,17 @@ class DownloadResource(Resource):
 
     @defer.inlineCallbacks
     def _respond_remote_file(self, request, server_name, media_id, name):
+        # don't forward requests for remote media if allow_remote is false
+        allow_remote = synapse.http.servlet.parse_boolean(
+            request, "allow_remote", default=True)
+        if not allow_remote:
+            logger.info(
+                "Rejecting request for remote media %s/%s due to allow_remote",
+                server_name, media_id,
+            )
+            respond_404(request)
+            return
+
         media_info = yield self.media_repo.get_remote_media(server_name, media_id)
 
         media_type = media_info["media_type"]
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 481ffee200..c43b185e08 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -13,22 +13,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from twisted.internet import defer, threads
+import twisted.internet.error
+import twisted.web.http
+from twisted.web.resource import Resource
+
 from .upload_resource import UploadResource
 from .download_resource import DownloadResource
 from .thumbnail_resource import ThumbnailResource
 from .identicon_resource import IdenticonResource
 from .preview_url_resource import PreviewUrlResource
 from .filepath import MediaFilePaths
-
-from twisted.web.resource import Resource
-
 from .thumbnailer import Thumbnailer
 
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.util.stringutils import random_string
-from synapse.api.errors import SynapseError
-
-from twisted.internet import defer, threads
+from synapse.api.errors import SynapseError, HttpResponseException, \
+    NotFoundError
 
 from synapse.util.async import Linearizer
 from synapse.util.stringutils import is_ascii
@@ -157,11 +158,34 @@ class MediaRepository(object):
                 try:
                     length, headers = yield self.client.get_file(
                         server_name, request_path, output_stream=f,
-                        max_size=self.max_upload_size,
+                        max_size=self.max_upload_size, args={
+                            # tell the remote server to 404 if it doesn't
+                            # recognise the server_name, to make sure we don't
+                            # end up with a routing loop.
+                            "allow_remote": "false",
+                        }
                     )
-                except Exception as e:
-                    logger.warn("Failed to fetch remoted media %r", e)
-                    raise SynapseError(502, "Failed to fetch remoted media")
+                except twisted.internet.error.DNSLookupError as e:
+                    logger.warn("HTTP error fetching remote media %s/%s: %r",
+                                server_name, media_id, e)
+                    raise NotFoundError()
+
+                except HttpResponseException as e:
+                    logger.warn("HTTP error fetching remote media %s/%s: %s",
+                                server_name, media_id, e.response)
+                    if e.code == twisted.web.http.NOT_FOUND:
+                        raise SynapseError.from_http_response_exception(e)
+                    raise SynapseError(502, "Failed to fetch remote media")
+
+                except SynapseError:
+                    logger.exception("Failed to fetch remote media %s/%s",
+                                     server_name, media_id)
+                    raise
+
+                except Exception:
+                    logger.exception("Failed to fetch remote media %s/%s",
+                                     server_name, media_id)
+                    raise SynapseError(502, "Failed to fetch remote media")
 
             media_type = headers["Content-Type"][0]
             time_now_ms = self.clock.time_msec()