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authorErik Johnston <erik@matrix.org>2019-01-25 17:19:31 +0000
committerErik Johnston <erik@matrix.org>2019-01-29 11:13:00 +0000
commitbe47cfa9c97b4acfd884440f1953ed000225eb37 (patch)
tree3e274c1b99d45ba4f1eba89d4553060b301f83d1 /synapse
parentMake add_hashes_and_signatures operate on dicts (diff)
downloadsynapse-be47cfa9c97b4acfd884440f1953ed000225eb37.tar.xz
Refactor event building into EventBuilder
This is so that everything is done in one place, making it easier to
change the event format based on room version
Diffstat (limited to 'synapse')
-rw-r--r--synapse/events/builder.py284
-rw-r--r--synapse/federation/federation_client.py20
-rw-r--r--synapse/handlers/message.py34
-rw-r--r--synapse/server.py5
-rw-r--r--synapse/storage/event_federation.py23
5 files changed, 254 insertions, 112 deletions
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 7e63371095..225b5fd670 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -13,79 +13,156 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import copy
+import attr
 
-from synapse.api.constants import RoomVersions
+from twisted.internet import defer
+
+from synapse.api.constants import (
+    KNOWN_EVENT_FORMAT_VERSIONS,
+    KNOWN_ROOM_VERSIONS,
+    MAX_DEPTH,
+)
+from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.types import EventID
 from synapse.util.stringutils import random_string
 
-from . import EventBase, FrozenEvent, _event_dict_property
+from . import (
+    _EventInternalMetadata,
+    event_type_from_format_version,
+    room_version_to_event_format,
+)
 
 
-def get_event_builder(room_version, key_values={}, internal_metadata_dict={}):
-    """Generate an event builder appropriate for the given room version
+@attr.s(slots=True, cmp=False, frozen=True)
+class EventBuilder(object):
+    """A format independent event builder used to build up the event content
+    before signing the event.
 
-    Args:
-        room_version (str): Version of the room that we're creating an
-            event builder for
-        key_values (dict): Fields used as the basis of the new event
-        internal_metadata_dict (dict): Used to create the `_EventInternalMetadata`
-            object.
+    (Note that while objects of this class are frozen, the
+    content/unsigned/internal_metadata fields are still mutable)
 
-    Returns:
-        EventBuilder
+    Attributes:
+        format_version (int): Event format version
+        room_id (str)
+        type (str)
+        sender (str)
+        content (dict)
+        unsigned (dict)
+        internal_metadata (_EventInternalMetadata)
+
+        _state (StateHandler)
+        _auth (synapse.api.Auth)
+        _store (DataStore)
+        _clock (Clock)
+        _hostname (str): The hostname of the server creating the event
+        _signing_key: The signing key to use to sign the event as the server
     """
-    if room_version in {
-        RoomVersions.V1,
-        RoomVersions.V2,
-        RoomVersions.VDH_TEST,
-        RoomVersions.STATE_V2_TEST,
-    }:
-        return EventBuilder(key_values, internal_metadata_dict)
-    else:
-        raise Exception(
-            "No event format defined for version %r" % (room_version,)
-        )
 
+    _state = attr.ib()
+    _auth = attr.ib()
+    _store = attr.ib()
+    _clock = attr.ib()
+    _hostname = attr.ib()
+    _signing_key = attr.ib()
+
+    format_version = attr.ib()
+
+    room_id = attr.ib()
+    type = attr.ib()
+    sender = attr.ib()
+
+    content = attr.ib(default=attr.Factory(dict))
+    unsigned = attr.ib(default=attr.Factory(dict))
+
+    # These only exist on a subset of events, so they raise AttributeError if
+    # someone tries to get them when they don't exist.
+    _state_key = attr.ib(default=None)
+    _redacts = attr.ib(default=None)
+
+    internal_metadata = attr.ib(default=attr.Factory(lambda: _EventInternalMetadata({})))
+
+    @property
+    def state_key(self):
+        if self._state_key is not None:
+            return self._state_key
+
+        raise AttributeError("state_key")
+
+    def is_state(self):
+        return self._state_key is not None
 
-class EventBuilder(EventBase):
-    def __init__(self, key_values={}, internal_metadata_dict={}):
-        signatures = copy.deepcopy(key_values.pop("signatures", {}))
-        unsigned = copy.deepcopy(key_values.pop("unsigned", {}))
+    @defer.inlineCallbacks
+    def build(self, prev_event_ids):
+        """Transform into a fully signed and hashed event
 
-        super(EventBuilder, self).__init__(
-            key_values,
-            signatures=signatures,
-            unsigned=unsigned,
-            internal_metadata_dict=internal_metadata_dict,
+        Args:
+            prev_event_ids (list[str]): The event IDs to use as the prev events
+
+        Returns:
+            Deferred[FrozenEvent]
+        """
+
+        state_ids = yield self._state.get_current_state_ids(
+            self.room_id, prev_event_ids,
+        )
+        auth_ids = yield self._auth.compute_auth_events(
+            self, state_ids,
         )
 
-    event_id = _event_dict_property("event_id")
-    state_key = _event_dict_property("state_key")
-    type = _event_dict_property("type")
+        auth_events = yield self._store.add_event_hashes(auth_ids)
+        prev_events = yield self._store.add_event_hashes(prev_event_ids)
 
-    def build(self):
-        return FrozenEvent.from_event(self)
+        old_depth = yield self._store.get_max_depth_of(
+            prev_event_ids,
+        )
+        depth = old_depth + 1
 
+        # we cap depth of generated events, to ensure that they are not
+        # rejected by other servers (and so that they can be persisted in
+        # the db)
+        depth = min(depth, MAX_DEPTH)
 
-class EventBuilderFactory(object):
-    def __init__(self, clock, hostname):
-        self.clock = clock
-        self.hostname = hostname
+        event_dict = {
+            "auth_events": auth_events,
+            "prev_events": prev_events,
+            "type": self.type,
+            "room_id": self.room_id,
+            "sender": self.sender,
+            "content": self.content,
+            "unsigned": self.unsigned,
+            "depth": depth,
+            "prev_state": [],
+        }
+
+        if self.is_state():
+            event_dict["state_key"] = self._state_key
 
-        self.event_id_count = 0
+        if self._redacts is not None:
+            event_dict["redacts"] = self._redacts
 
-    def create_event_id(self):
-        i = str(self.event_id_count)
-        self.event_id_count += 1
+        defer.returnValue(
+            create_local_event_from_event_dict(
+                clock=self._clock,
+                hostname=self._hostname,
+                signing_key=self._signing_key,
+                format_version=self.format_version,
+                event_dict=event_dict,
+                internal_metadata_dict=self.internal_metadata.get_dict(),
+            )
+        )
 
-        local_part = str(int(self.clock.time())) + i + random_string(5)
 
-        e_id = EventID(local_part, self.hostname)
+class EventBuilderFactory(object):
+    def __init__(self, hs):
+        self.clock = hs.get_clock()
+        self.hostname = hs.hostname
+        self.signing_key = hs.config.signing_key[0]
 
-        return e_id.to_string()
+        self.store = hs.get_datastore()
+        self.state = hs.get_state_handler()
+        self.auth = hs.get_auth()
 
-    def new(self, room_version, key_values={}):
+    def new(self, room_version, key_values):
         """Generate an event builder appropriate for the given room version
 
         Args:
@@ -98,27 +175,104 @@ class EventBuilderFactory(object):
         """
 
         # There's currently only the one event version defined
-        if room_version not in {
-            RoomVersions.V1,
-            RoomVersions.V2,
-            RoomVersions.VDH_TEST,
-            RoomVersions.STATE_V2_TEST,
-        }:
+        if room_version not in KNOWN_ROOM_VERSIONS:
             raise Exception(
                 "No event format defined for version %r" % (room_version,)
             )
 
-        key_values["event_id"] = self.create_event_id()
+        key_values["event_id"] = _create_event_id(self.clock, self.hostname)
+
+        return EventBuilder(
+            store=self.store,
+            state=self.state,
+            auth=self.auth,
+            clock=self.clock,
+            hostname=self.hostname,
+            signing_key=self.signing_key,
+            format_version=room_version_to_event_format(room_version),
+            type=key_values["type"],
+            state_key=key_values.get("state_key"),
+            room_id=key_values["room_id"],
+            sender=key_values["sender"],
+            content=key_values.get("content", {}),
+            unsigned=key_values.get("unsigned", {}),
+            redacts=key_values.get("redacts", None),
+        )
+
+
+def create_local_event_from_event_dict(clock, hostname, signing_key,
+                                       format_version, event_dict,
+                                       internal_metadata_dict=None):
+    """Takes a fully formed event dict, ensuring that fields like `origin`
+    and `origin_server_ts` have correct values for a locally produced event,
+    then signs and hashes it.
+
+    Args:
+        clock (Clock)
+        hostname (str)
+        signing_key
+        format_version (int)
+        event_dict (dict)
+        internal_metadata_dict (dict|None)
+
+    Returns:
+        FrozenEvent
+    """
+
+    # There's currently only the one event version defined
+    if format_version not in KNOWN_EVENT_FORMAT_VERSIONS:
+        raise Exception(
+            "No event format defined for version %r" % (format_version,)
+        )
+
+    if internal_metadata_dict is None:
+        internal_metadata_dict = {}
+
+    time_now = int(clock.time_msec())
+
+    event_dict["event_id"] = _create_event_id(clock, hostname)
+
+    event_dict["origin"] = hostname
+    event_dict["origin_server_ts"] = time_now
+
+    event_dict.setdefault("unsigned", {})
+    age = event_dict["unsigned"].pop("age", 0)
+    event_dict["unsigned"].setdefault("age_ts", time_now - age)
+
+    event_dict.setdefault("signatures", {})
+
+    add_hashes_and_signatures(
+        event_dict,
+        hostname,
+        signing_key,
+    )
+    return event_type_from_format_version(format_version)(
+        event_dict, internal_metadata_dict=internal_metadata_dict,
+    )
+
+
+# A counter used when generating new event IDs
+_event_id_counter = 0
+
+
+def _create_event_id(clock, hostname):
+    """Create a new event ID
+
+    Args:
+        clock (Clock)
+        hostname (str): The server name for the event ID
+
+    Returns:
+        str
+    """
 
-        time_now = int(self.clock.time_msec())
+    global _event_id_counter
 
-        key_values.setdefault("origin", self.hostname)
-        key_values.setdefault("origin_server_ts", time_now)
+    i = str(_event_id_counter)
+    _event_id_counter += 1
 
-        key_values.setdefault("unsigned", {})
-        age = key_values["unsigned"].pop("age", 0)
-        key_values["unsigned"].setdefault("age_ts", time_now - age)
+    local_part = str(int(clock.time())) + i + random_string(5)
 
-        key_values["signatures"] = {}
+    e_id = EventID(local_part, hostname)
 
-        return EventBuilder(key_values=key_values,)
+    return e_id.to_string()
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 71809893c5..be3bb59431 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -37,8 +37,7 @@ from synapse.api.errors import (
     HttpResponseException,
     SynapseError,
 )
-from synapse.crypto.event_signing import add_hashes_and_signatures
-from synapse.events import room_version_to_event_format
+from synapse.events import builder, room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.util import logcontext, unwrapFirstError
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -72,7 +71,8 @@ class FederationClient(FederationBase):
         self.state = hs.get_state_handler()
         self.transport_layer = hs.get_federation_transport_client()
 
-        self.event_builder_factory = hs.get_event_builder_factory()
+        self.hostname = hs.hostname
+        self.signing_key = hs.config.signing_key[0]
 
         self._get_pdu_cache = ExpiringCache(
             cache_name="get_pdu_cache",
@@ -608,18 +608,10 @@ class FederationClient(FederationBase):
             if "prev_state" not in pdu_dict:
                 pdu_dict["prev_state"] = []
 
-            # Strip off the fields that we want to clobber.
-            pdu_dict.pop("origin", None)
-            pdu_dict.pop("origin_server_ts", None)
-            pdu_dict.pop("unsigned", None)
-
-            builder = self.event_builder_factory.new(room_version, pdu_dict)
-            add_hashes_and_signatures(
-                builder,
-                self.hs.hostname,
-                self.hs.config.signing_key[0]
+            ev = builder.create_local_event_from_event_dict(
+                self._clock, self.hostname, self.signing_key,
+                format_version=event_format, event_dict=pdu_dict,
             )
-            ev = builder.build()
 
             defer.returnValue(
                 (destination, ev, event_format)
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 05d1370c18..ac6f4fd985 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -22,7 +22,7 @@ from canonicaljson import encode_canonical_json, json
 from twisted.internet import defer
 from twisted.internet.defer import succeed
 
-from synapse.api.constants import MAX_DEPTH, EventTypes, Membership, RoomVersions
+from synapse.api.constants import EventTypes, Membership, RoomVersions
 from synapse.api.errors import (
     AuthError,
     Codes,
@@ -31,7 +31,6 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.api.urls import ConsentURIBuilder
-from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
@@ -545,40 +544,17 @@ class EventCreationHandler(object):
             prev_events_and_hashes = \
                 yield self.store.get_prev_events_for_room(builder.room_id)
 
-        if prev_events_and_hashes:
-            depth = max([d for _, _, d in prev_events_and_hashes]) + 1
-            # we cap depth of generated events, to ensure that they are not
-            # rejected by other servers (and so that they can be persisted in
-            # the db)
-            depth = min(depth, MAX_DEPTH)
-        else:
-            depth = 1
-
         prev_events = [
             (event_id, prev_hashes)
             for event_id, prev_hashes, _ in prev_events_and_hashes
         ]
 
-        builder.prev_events = prev_events
-        builder.depth = depth
-
-        context = yield self.state.compute_event_context(builder)
-        if requester:
-            context.app_service = requester.app_service
-
-        if builder.is_state():
-            builder.prev_state = yield self.store.add_event_hashes(
-                context.prev_state_events
-            )
-
-        yield self.auth.add_auth_events(builder, context)
-
-        signing_key = self.hs.config.signing_key[0]
-        add_hashes_and_signatures(
-            builder, self.server_name, signing_key
+        event = yield builder.build(
+            prev_event_ids=[p for p, _ in prev_events],
         )
+        context = yield self.state.compute_event_context(event)
 
-        event = builder.build()
+        self.validator.validate_new(event)
 
         logger.debug(
             "Created event %s",
diff --git a/synapse/server.py b/synapse/server.py
index c8914302cf..6c52101616 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -355,10 +355,7 @@ class HomeServer(object):
         return Keyring(self)
 
     def build_event_builder_factory(self):
-        return EventBuilderFactory(
-            clock=self.get_clock(),
-            hostname=self.hostname,
-        )
+        return EventBuilderFactory(self)
 
     def build_filtering(self):
         return Filtering(self)
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index d3b9dea1d6..38809ed0fc 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -125,6 +125,29 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore,
 
         return dict(txn)
 
+    @defer.inlineCallbacks
+    def get_max_depth_of(self, event_ids):
+        """Returns the max depth of a set of event IDs
+
+        Args:
+            event_ids (list[str])
+
+        Returns
+            Deferred[int]
+        """
+        rows = yield self._simple_select_many_batch(
+            table="events",
+            column="event_id",
+            iterable=event_ids,
+            retcols=("depth",),
+            desc="get_max_depth_of",
+        )
+
+        if not rows:
+            defer.returnValue(0)
+        else:
+            defer.returnValue(max(row["depth"] for row in rows))
+
     def _get_oldest_events_in_room_txn(self, txn, room_id):
         return self._simple_select_onecol_txn(
             txn,