Merge branch 'release-v0.24.0' of github.com:matrix-org/synapse v0.24.0

3 files changed, 954 insertions, 0 deletions

diff --git a/synapse/groups/__init__.py b/synapse/groups/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/synapse/groups/__init__.py
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py
new file mode 100644
index 0000000000..b751cf5e43
--- /dev/null
+++ b/synapse/groups/attestations.py
@@ -0,0 +1,151 @@
+# -*- coding: utf-8 -*-
+# 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.
+# 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 twisted.internet import defer
+
+from synapse.api.errors import SynapseError
+from synapse.types import get_domain_from_id
+from synapse.util.logcontext import preserve_fn
+
+from signedjson.sign import sign_json
+
+
+# Default validity duration for new attestations we create
+DEFAULT_ATTESTATION_LENGTH_MS = 3 * 24 * 60 * 60 * 1000
+
+# Start trying to update our attestations when they come this close to expiring
+UPDATE_ATTESTATION_TIME_MS = 1 * 24 * 60 * 60 * 1000
+
+
+class GroupAttestationSigning(object):
+    """Creates and verifies group attestations.
+    """
+    def __init__(self, hs):
+        self.keyring = hs.get_keyring()
+        self.clock = hs.get_clock()
+        self.server_name = hs.hostname
+        self.signing_key = hs.config.signing_key[0]
+
+    @defer.inlineCallbacks
+    def verify_attestation(self, attestation, group_id, user_id, server_name=None):
+        """Verifies that the given attestation matches the given parameters.
+
+        An optional server_name can be supplied to explicitly set which server's
+        signature is expected. Otherwise assumes that either the group_id or user_id
+        is local and uses the other's server as the one to check.
+        """
+
+        if not server_name:
+            if get_domain_from_id(group_id) == self.server_name:
+                server_name = get_domain_from_id(user_id)
+            elif get_domain_from_id(user_id) == self.server_name:
+                server_name = get_domain_from_id(group_id)
+            else:
+                raise Exception("Expected either group_id or user_id to be local")
+
+        if user_id != attestation["user_id"]:
+            raise SynapseError(400, "Attestation has incorrect user_id")
+
+        if group_id != attestation["group_id"]:
+            raise SynapseError(400, "Attestation has incorrect group_id")
+        valid_until_ms = attestation["valid_until_ms"]
+
+        # TODO: We also want to check that *new* attestations that people give
+        # us to store are valid for at least a little while.
+        if valid_until_ms < self.clock.time_msec():
+            raise SynapseError(400, "Attestation expired")
+
+        yield self.keyring.verify_json_for_server(server_name, attestation)
+
+    def create_attestation(self, group_id, user_id):
+        """Create an attestation for the group_id and user_id with default
+        validity length.
+        """
+        return sign_json({
+            "group_id": group_id,
+            "user_id": user_id,
+            "valid_until_ms": self.clock.time_msec() + DEFAULT_ATTESTATION_LENGTH_MS,
+        }, self.server_name, self.signing_key)
+
+
+class GroupAttestionRenewer(object):
+    """Responsible for sending and receiving attestation updates.
+    """
+
+    def __init__(self, hs):
+        self.clock = hs.get_clock()
+        self.store = hs.get_datastore()
+        self.assestations = hs.get_groups_attestation_signing()
+        self.transport_client = hs.get_federation_transport_client()
+        self.is_mine_id = hs.is_mine_id
+        self.attestations = hs.get_groups_attestation_signing()
+
+        self._renew_attestations_loop = self.clock.looping_call(
+            self._renew_attestations, 30 * 60 * 1000,
+        )
+
+    @defer.inlineCallbacks
+    def on_renew_attestation(self, group_id, user_id, content):
+        """When a remote updates an attestation
+        """
+        attestation = content["attestation"]
+
+        if not self.is_mine_id(group_id) and not self.is_mine_id(user_id):
+            raise SynapseError(400, "Neither user not group are on this server")
+
+        yield self.attestations.verify_attestation(
+            attestation,
+            user_id=user_id,
+            group_id=group_id,
+        )
+
+        yield self.store.update_remote_attestion(group_id, user_id, attestation)
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def _renew_attestations(self):
+        """Called periodically to check if we need to update any of our attestations
+        """
+
+        now = self.clock.time_msec()
+
+        rows = yield self.store.get_attestations_need_renewals(
+            now + UPDATE_ATTESTATION_TIME_MS
+        )
+
+        @defer.inlineCallbacks
+        def _renew_attestation(group_id, user_id):
+            attestation = self.attestations.create_attestation(group_id, user_id)
+
+            if self.is_mine_id(group_id):
+                destination = get_domain_from_id(user_id)
+            else:
+                destination = get_domain_from_id(group_id)
+
+            yield self.transport_client.renew_group_attestation(
+                destination, group_id, user_id,
+                content={"attestation": attestation},
+            )
+
+            yield self.store.update_attestation_renewal(
+                group_id, user_id, attestation
+            )
+
+        for row in rows:
+            group_id = row["group_id"]
+            user_id = row["user_id"]
+
+            preserve_fn(_renew_attestation)(group_id, user_id)
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
new file mode 100644
index 0000000000..fc4edb7f04
--- /dev/null
+++ b/synapse/groups/groups_server.py
@@ -0,0 +1,803 @@
+# -*- coding: utf-8 -*-
+# 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.
+# 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 twisted.internet import defer
+
+from synapse.api.errors import SynapseError
+from synapse.types import UserID, get_domain_from_id, RoomID, GroupID
+
+
+import logging
+import urllib
+
+logger = logging.getLogger(__name__)
+
+
+# TODO: Allow users to "knock" or simpkly join depending on rules
+# TODO: Federation admin APIs
+# TODO: is_priveged flag to users and is_public to users and rooms
+# TODO: Audit log for admins (profile updates, membership changes, users who tried
+#       to join but were rejected, etc)
+# TODO: Flairs
+
+
+class GroupsServerHandler(object):
+    def __init__(self, hs):
+        self.hs = hs
+        self.store = hs.get_datastore()
+        self.room_list_handler = hs.get_room_list_handler()
+        self.auth = hs.get_auth()
+        self.clock = hs.get_clock()
+        self.keyring = hs.get_keyring()
+        self.is_mine_id = hs.is_mine_id
+        self.signing_key = hs.config.signing_key[0]
+        self.server_name = hs.hostname
+        self.attestations = hs.get_groups_attestation_signing()
+        self.transport_client = hs.get_federation_transport_client()
+        self.profile_handler = hs.get_profile_handler()
+
+        # Ensure attestations get renewed
+        hs.get_groups_attestation_renewer()
+
+    @defer.inlineCallbacks
+    def check_group_is_ours(self, group_id, and_exists=False, and_is_admin=None):
+        """Check that the group is ours, and optionally if it exists.
+
+        If group does exist then return group.
+
+        Args:
+            group_id (str)
+            and_exists (bool): whether to also check if group exists
+            and_is_admin (str): whether to also check if given str is a user_id
+                that is an admin
+        """
+        if not self.is_mine_id(group_id):
+            raise SynapseError(400, "Group not on this server")
+
+        group = yield self.store.get_group(group_id)
+        if and_exists and not group:
+            raise SynapseError(404, "Unknown group")
+
+        if and_is_admin:
+            is_admin = yield self.store.is_user_admin_in_group(group_id, and_is_admin)
+            if not is_admin:
+                raise SynapseError(403, "User is not admin in group")
+
+        defer.returnValue(group)
+
+    @defer.inlineCallbacks
+    def get_group_summary(self, group_id, requester_user_id):
+        """Get the summary for a group as seen by requester_user_id.
+
+        The group summary consists of the profile of the room, and a curated
+        list of users and rooms. These list *may* be organised by role/category.
+        The roles/categories are ordered, and so are the users/rooms within them.
+
+        A user/room may appear in multiple roles/categories.
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        is_user_in_group = yield self.store.is_user_in_group(requester_user_id, group_id)
+
+        profile = yield self.get_group_profile(group_id, requester_user_id)
+
+        users, roles = yield self.store.get_users_for_summary_by_role(
+            group_id, include_private=is_user_in_group,
+        )
+
+        # TODO: Add profiles to users
+
+        rooms, categories = yield self.store.get_rooms_for_summary_by_category(
+            group_id, include_private=is_user_in_group,
+        )
+
+        for room_entry in rooms:
+            room_id = room_entry["room_id"]
+            joined_users = yield self.store.get_users_in_room(room_id)
+            entry = yield self.room_list_handler.generate_room_entry(
+                room_id, len(joined_users),
+                with_alias=False, allow_private=True,
+            )
+            entry = dict(entry)  # so we don't change whats cached
+            entry.pop("room_id", None)
+
+            room_entry["profile"] = entry
+
+        rooms.sort(key=lambda e: e.get("order", 0))
+
+        for entry in users:
+            user_id = entry["user_id"]
+
+            if not self.is_mine_id(requester_user_id):
+                attestation = yield self.store.get_remote_attestation(group_id, user_id)
+                if not attestation:
+                    continue
+
+                entry["attestation"] = attestation
+            else:
+                entry["attestation"] = self.attestations.create_attestation(
+                    group_id, user_id,
+                )
+
+            user_profile = yield self.profile_handler.get_profile_from_cache(user_id)
+            entry.update(user_profile)
+
+        users.sort(key=lambda e: e.get("order", 0))
+
+        membership_info = yield self.store.get_users_membership_info_in_group(
+            group_id, requester_user_id,
+        )
+
+        defer.returnValue({
+            "profile": profile,
+            "users_section": {
+                "users": users,
+                "roles": roles,
+                "total_user_count_estimate": 0,  # TODO
+            },
+            "rooms_section": {
+                "rooms": rooms,
+                "categories": categories,
+                "total_room_count_estimate": 0,  # TODO
+            },
+            "user": membership_info,
+        })
+
+    @defer.inlineCallbacks
+    def update_group_summary_room(self, group_id, user_id, room_id, category_id, content):
+        """Add/update a room to the group summary
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        RoomID.from_string(room_id)  # Ensure valid room id
+
+        order = content.get("order", None)
+
+        is_public = _parse_visibility_from_contents(content)
+
+        yield self.store.add_room_to_summary(
+            group_id=group_id,
+            room_id=room_id,
+            category_id=category_id,
+            order=order,
+            is_public=is_public,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def delete_group_summary_room(self, group_id, user_id, room_id, category_id):
+        """Remove a room from the summary
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        yield self.store.remove_room_from_summary(
+            group_id=group_id,
+            room_id=room_id,
+            category_id=category_id,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def get_group_categories(self, group_id, user_id):
+        """Get all categories in a group (as seen by user)
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        categories = yield self.store.get_group_categories(
+            group_id=group_id,
+        )
+        defer.returnValue({"categories": categories})
+
+    @defer.inlineCallbacks
+    def get_group_category(self, group_id, user_id, category_id):
+        """Get a specific category in a group (as seen by user)
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        res = yield self.store.get_group_category(
+            group_id=group_id,
+            category_id=category_id,
+        )
+
+        defer.returnValue(res)
+
+    @defer.inlineCallbacks
+    def update_group_category(self, group_id, user_id, category_id, content):
+        """Add/Update a group category
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        is_public = _parse_visibility_from_contents(content)
+        profile = content.get("profile")
+
+        yield self.store.upsert_group_category(
+            group_id=group_id,
+            category_id=category_id,
+            is_public=is_public,
+            profile=profile,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def delete_group_category(self, group_id, user_id, category_id):
+        """Delete a group category
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        yield self.store.remove_group_category(
+            group_id=group_id,
+            category_id=category_id,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def get_group_roles(self, group_id, user_id):
+        """Get all roles in a group (as seen by user)
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        roles = yield self.store.get_group_roles(
+            group_id=group_id,
+        )
+        defer.returnValue({"roles": roles})
+
+    @defer.inlineCallbacks
+    def get_group_role(self, group_id, user_id, role_id):
+        """Get a specific role in a group (as seen by user)
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        res = yield self.store.get_group_role(
+            group_id=group_id,
+            role_id=role_id,
+        )
+        defer.returnValue(res)
+
+    @defer.inlineCallbacks
+    def update_group_role(self, group_id, user_id, role_id, content):
+        """Add/update a role in a group
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        is_public = _parse_visibility_from_contents(content)
+
+        profile = content.get("profile")
+
+        yield self.store.upsert_group_role(
+            group_id=group_id,
+            role_id=role_id,
+            is_public=is_public,
+            profile=profile,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def delete_group_role(self, group_id, user_id, role_id):
+        """Remove role from group
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True, and_is_admin=user_id)
+
+        yield self.store.remove_group_role(
+            group_id=group_id,
+            role_id=role_id,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def update_group_summary_user(self, group_id, requester_user_id, user_id, role_id,
+                                  content):
+        """Add/update a users entry in the group summary
+        """
+        yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id,
+        )
+
+        order = content.get("order", None)
+
+        is_public = _parse_visibility_from_contents(content)
+
+        yield self.store.add_user_to_summary(
+            group_id=group_id,
+            user_id=user_id,
+            role_id=role_id,
+            order=order,
+            is_public=is_public,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def delete_group_summary_user(self, group_id, requester_user_id, user_id, role_id):
+        """Remove a user from the group summary
+        """
+        yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id,
+        )
+
+        yield self.store.remove_user_from_summary(
+            group_id=group_id,
+            user_id=user_id,
+            role_id=role_id,
+        )
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def get_group_profile(self, group_id, requester_user_id):
+        """Get the group profile as seen by requester_user_id
+        """
+
+        yield self.check_group_is_ours(group_id)
+
+        group_description = yield self.store.get_group(group_id)
+
+        if group_description:
+            defer.returnValue(group_description)
+        else:
+            raise SynapseError(404, "Unknown group")
+
+    @defer.inlineCallbacks
+    def update_group_profile(self, group_id, requester_user_id, content):
+        """Update the group profile
+        """
+        yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id,
+        )
+
+        profile = {}
+        for keyname in ("name", "avatar_url", "short_description",
+                        "long_description"):
+            if keyname in content:
+                value = content[keyname]
+                if not isinstance(value, basestring):
+                    raise SynapseError(400, "%r value is not a string" % (keyname,))
+                profile[keyname] = value
+
+        yield self.store.update_group_profile(group_id, profile)
+
+    @defer.inlineCallbacks
+    def get_users_in_group(self, group_id, requester_user_id):
+        """Get the users in group as seen by requester_user_id.
+
+        The ordering is arbitrary at the moment
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        is_user_in_group = yield self.store.is_user_in_group(requester_user_id, group_id)
+
+        user_results = yield self.store.get_users_in_group(
+            group_id, include_private=is_user_in_group,
+        )
+
+        chunk = []
+        for user_result in user_results:
+            g_user_id = user_result["user_id"]
+            is_public = user_result["is_public"]
+
+            entry = {"user_id": g_user_id}
+
+            profile = yield self.profile_handler.get_profile_from_cache(g_user_id)
+            entry.update(profile)
+
+            if not is_public:
+                entry["is_public"] = False
+
+            if not self.is_mine_id(g_user_id):
+                attestation = yield self.store.get_remote_attestation(group_id, g_user_id)
+                if not attestation:
+                    continue
+
+                entry["attestation"] = attestation
+            else:
+                entry["attestation"] = self.attestations.create_attestation(
+                    group_id, g_user_id,
+                )
+
+            chunk.append(entry)
+
+        # TODO: If admin add lists of users whose attestations have timed out
+
+        defer.returnValue({
+            "chunk": chunk,
+            "total_user_count_estimate": len(user_results),
+        })
+
+    @defer.inlineCallbacks
+    def get_invited_users_in_group(self, group_id, requester_user_id):
+        """Get the users that have been invited to a group as seen by requester_user_id.
+
+        The ordering is arbitrary at the moment
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        is_user_in_group = yield self.store.is_user_in_group(requester_user_id, group_id)
+
+        if not is_user_in_group:
+            raise SynapseError(403, "User not in group")
+
+        invited_users = yield self.store.get_invited_users_in_group(group_id)
+
+        user_profiles = []
+
+        for user_id in invited_users:
+            user_profile = {
+                "user_id": user_id
+            }
+            try:
+                profile = yield self.profile_handler.get_profile_from_cache(user_id)
+                user_profile.update(profile)
+            except Exception as e:
+                logger.warn("Error getting profile for %s: %s", user_id, e)
+            user_profiles.append(user_profile)
+
+        defer.returnValue({
+            "chunk": user_profiles,
+            "total_user_count_estimate": len(invited_users),
+        })
+
+    @defer.inlineCallbacks
+    def get_rooms_in_group(self, group_id, requester_user_id):
+        """Get the rooms in group as seen by requester_user_id
+
+        This returns rooms in order of decreasing number of joined users
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        is_user_in_group = yield self.store.is_user_in_group(requester_user_id, group_id)
+
+        room_results = yield self.store.get_rooms_in_group(
+            group_id, include_private=is_user_in_group,
+        )
+
+        chunk = []
+        for room_result in room_results:
+            room_id = room_result["room_id"]
+            is_public = room_result["is_public"]
+
+            joined_users = yield self.store.get_users_in_room(room_id)
+            entry = yield self.room_list_handler.generate_room_entry(
+                room_id, len(joined_users),
+                with_alias=False, allow_private=True,
+            )
+
+            if not entry:
+                continue
+
+            if not is_public:
+                entry["is_public"] = False
+
+            chunk.append(entry)
+
+        chunk.sort(key=lambda e: -e["num_joined_members"])
+
+        defer.returnValue({
+            "chunk": chunk,
+            "total_room_count_estimate": len(room_results),
+        })
+
+    @defer.inlineCallbacks
+    def add_room_to_group(self, group_id, requester_user_id, room_id, content):
+        """Add room to group
+        """
+        RoomID.from_string(room_id)  # Ensure valid room id
+
+        yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id
+        )
+
+        is_public = _parse_visibility_from_contents(content)
+
+        yield self.store.add_room_to_group(group_id, room_id, is_public=is_public)
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def remove_room_from_group(self, group_id, requester_user_id, room_id):
+        """Remove room from group
+        """
+        yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id
+        )
+
+        yield self.store.remove_room_from_group(group_id, room_id)
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def invite_to_group(self, group_id, user_id, requester_user_id, content):
+        """Invite user to group
+        """
+
+        group = yield self.check_group_is_ours(
+            group_id, and_exists=True, and_is_admin=requester_user_id
+        )
+
+        # TODO: Check if user knocked
+        # TODO: Check if user is already invited
+
+        content = {
+            "profile": {
+                "name": group["name"],
+                "avatar_url": group["avatar_url"],
+            },
+            "inviter": requester_user_id,
+        }
+
+        if self.hs.is_mine_id(user_id):
+            groups_local = self.hs.get_groups_local_handler()
+            res = yield groups_local.on_invite(group_id, user_id, content)
+            local_attestation = None
+        else:
+            local_attestation = self.attestations.create_attestation(group_id, user_id)
+            content.update({
+                "attestation": local_attestation,
+            })
+
+            res = yield self.transport_client.invite_to_group_notification(
+                get_domain_from_id(user_id), group_id, user_id, content
+            )
+
+            user_profile = res.get("user_profile", {})
+            yield self.store.add_remote_profile_cache(
+                user_id,
+                displayname=user_profile.get("displayname"),
+                avatar_url=user_profile.get("avatar_url"),
+            )
+
+        if res["state"] == "join":
+            if not self.hs.is_mine_id(user_id):
+                remote_attestation = res["attestation"]
+
+                yield self.attestations.verify_attestation(
+                    remote_attestation,
+                    user_id=user_id,
+                    group_id=group_id,
+                )
+            else:
+                remote_attestation = None
+
+            yield self.store.add_user_to_group(
+                group_id, user_id,
+                is_admin=False,
+                is_public=False,  # TODO
+                local_attestation=local_attestation,
+                remote_attestation=remote_attestation,
+            )
+        elif res["state"] == "invite":
+            yield self.store.add_group_invite(
+                group_id, user_id,
+            )
+            defer.returnValue({
+                "state": "invite"
+            })
+        elif res["state"] == "reject":
+            defer.returnValue({
+                "state": "reject"
+            })
+        else:
+            raise SynapseError(502, "Unknown state returned by HS")
+
+    @defer.inlineCallbacks
+    def accept_invite(self, group_id, user_id, content):
+        """User tries to accept an invite to the group.
+
+        This is different from them asking to join, and so should error if no
+        invite exists (and they're not a member of the group)
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        if not self.store.is_user_invited_to_local_group(group_id, user_id):
+            raise SynapseError(403, "User not invited to group")
+
+        if not self.hs.is_mine_id(user_id):
+            remote_attestation = content["attestation"]
+
+            yield self.attestations.verify_attestation(
+                remote_attestation,
+                user_id=user_id,
+                group_id=group_id,
+            )
+        else:
+            remote_attestation = None
+
+        local_attestation = self.attestations.create_attestation(group_id, user_id)
+
+        is_public = _parse_visibility_from_contents(content)
+
+        yield self.store.add_user_to_group(
+            group_id, user_id,
+            is_admin=False,
+            is_public=is_public,
+            local_attestation=local_attestation,
+            remote_attestation=remote_attestation,
+        )
+
+        defer.returnValue({
+            "state": "join",
+            "attestation": local_attestation,
+        })
+
+    @defer.inlineCallbacks
+    def knock(self, group_id, user_id, content):
+        """A user requests becoming a member of the group
+        """
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        raise NotImplementedError()
+
+    @defer.inlineCallbacks
+    def accept_knock(self, group_id, user_id, content):
+        """Accept a users knock to the room.
+
+        Errors if the user hasn't knocked, rather than inviting them.
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        raise NotImplementedError()
+
+    @defer.inlineCallbacks
+    def remove_user_from_group(self, group_id, user_id, requester_user_id, content):
+        """Remove a user from the group; either a user is leaving or and admin
+        kicked htem.
+        """
+
+        yield self.check_group_is_ours(group_id, and_exists=True)
+
+        is_kick = False
+        if requester_user_id != user_id:
+            is_admin = yield self.store.is_user_admin_in_group(
+                group_id, requester_user_id
+            )
+            if not is_admin:
+                raise SynapseError(403, "User is not admin in group")
+
+            is_kick = True
+
+        yield self.store.remove_user_from_group(
+            group_id, user_id,
+        )
+
+        if is_kick:
+            if self.hs.is_mine_id(user_id):
+                groups_local = self.hs.get_groups_local_handler()
+                yield groups_local.user_removed_from_group(group_id, user_id, {})
+            else:
+                yield self.transport_client.remove_user_from_group_notification(
+                    get_domain_from_id(user_id), group_id, user_id, {}
+                )
+
+        if not self.hs.is_mine_id(user_id):
+            yield self.store.maybe_delete_remote_profile_cache(user_id)
+
+        defer.returnValue({})
+
+    @defer.inlineCallbacks
+    def create_group(self, group_id, user_id, content):
+        group = yield self.check_group_is_ours(group_id)
+
+        _validate_group_id(group_id)
+
+        logger.info("Attempting to create group with ID: %r", group_id)
+        if group:
+            raise SynapseError(400, "Group already exists")
+
+        is_admin = yield self.auth.is_server_admin(UserID.from_string(user_id))
+        if not is_admin:
+            if not self.hs.config.enable_group_creation:
+                raise SynapseError(
+                    403, "Only server admin can create group on this server",
+                )
+            localpart = GroupID.from_string(group_id).localpart
+            if not localpart.startswith(self.hs.config.group_creation_prefix):
+                raise SynapseError(
+                    400,
+                    "Can only create groups with prefix %r on this server" % (
+                        self.hs.config.group_creation_prefix,
+                    ),
+                )
+
+        profile = content.get("profile", {})
+        name = profile.get("name")
+        avatar_url = profile.get("avatar_url")
+        short_description = profile.get("short_description")
+        long_description = profile.get("long_description")
+        user_profile = content.get("user_profile", {})
+
+        yield self.store.create_group(
+            group_id,
+            user_id,
+            name=name,
+            avatar_url=avatar_url,
+            short_description=short_description,
+            long_description=long_description,
+        )
+
+        if not self.hs.is_mine_id(user_id):
+            remote_attestation = content["attestation"]
+
+            yield self.attestations.verify_attestation(
+                remote_attestation,
+                user_id=user_id,
+                group_id=group_id,
+            )
+
+            local_attestation = self.attestations.create_attestation(group_id, user_id)
+        else:
+            local_attestation = None
+            remote_attestation = None
+
+        yield self.store.add_user_to_group(
+            group_id, user_id,
+            is_admin=True,
+            is_public=True,  # TODO
+            local_attestation=local_attestation,
+            remote_attestation=remote_attestation,
+        )
+
+        if not self.hs.is_mine_id(user_id):
+            yield self.store.add_remote_profile_cache(
+                user_id,
+                displayname=user_profile.get("displayname"),
+                avatar_url=user_profile.get("avatar_url"),
+            )
+
+        defer.returnValue({
+            "group_id": group_id,
+        })
+
+
+def _parse_visibility_from_contents(content):
+    """Given a content for a request parse out whether the entity should be
+    public or not
+    """
+
+    visibility = content.get("visibility")
+    if visibility:
+        vis_type = visibility["type"]
+        if vis_type not in ("public", "private"):
+            raise SynapseError(
+                400, "Synapse only supports 'public'/'private' visibility"
+            )
+        is_public = vis_type == "public"
+    else:
+        is_public = True
+
+    return is_public
+
+
+def _validate_group_id(group_id):
+    """Validates the group ID is valid for creation on this home server
+    """
+    localpart = GroupID.from_string(group_id).localpart
+
+    if localpart.lower() != localpart:
+        raise SynapseError(400, "Group ID must be lower case")
+
+    if urllib.quote(localpart.encode('utf-8')) != localpart:
+        raise SynapseError(
+            400,
+            "Group ID can only contain characters a-z, 0-9, or '_-./'",
+        )