Merge pull request #1828 from matrix-org/travis/spec/rooms-v3
Add specification for room version 3: Event IDs as hashespull/977/head
Travis Ralston
6 years ago
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GitHub
commit
df01acc6e2
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# Copyright 2019 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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type: object
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title: Persistent Data Unit
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description: A persistent data unit (event) for room version 3 and beyond.
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example:
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$ref: "../examples/pdu_v3.json"
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allOf:
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- $ref: "unsigned_pdu_base.yaml"
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- type: object
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properties:
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auth_events:
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type: array
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items:
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type: string
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description: Event ID.
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description: |-
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Event IDs for the authorization events that would
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allow this event to be in the room.
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example: ["$base64EncodedHash", "$AnotherEvent"]
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prev_events:
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type: array
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items:
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type: string
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description: Event ID.
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description: |-
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Event IDs for the most recent events in the room
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that the homeserver was aware of when it made this event.
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example: ["$base64EncodedHash", "$AnotherEvent"]
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hashes:
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type: object
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title: Event Hash
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description: |-
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Content hashes of the PDU, following the algorithm specified in `Signing Events`_.
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example: {
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"sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
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}
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properties:
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sha256:
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type: string
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description: The hash.
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example: ThisHashCoversAllFieldsInCaseThisIsRedacted
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required: ['sha256']
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signatures:
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type: object
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description: |-
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Signatures for the PDU, following the algorithm specified in `Signing Events`_.
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example: {
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"example.com": {
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"ed25519:key_version:": "86BytesOfSignatureOfTheRedactedEvent"
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}
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}
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additionalProperties:
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type: object
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title: Server Signatures
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additionalProperties:
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type: string
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required:
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- auth_events
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- prev_events
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- hashes
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- signatures
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# Copyright 2018 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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type: object
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title: Unsigned Persistent Data Unit
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description: An unsigned persistent data unit (event)
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example:
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$ref: "../examples/unsigned_pdu_base.json"
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properties:
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room_id:
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type: string
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description: Room identifier.
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example: "!abc123:matrix.org"
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sender:
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type: string
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description: The ID of the user sending the event.
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example: "@someone:matrix.org"
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origin:
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type: string
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description: The ``server_name`` of the homeserver that created this event.
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example: "matrix.org"
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origin_server_ts:
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type: integer
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format: int64
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description: Timestamp in milliseconds on origin homeserver when this event was created.
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example: 1234567890
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type:
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type: string
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description: Event type
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example: "m.room.message"
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state_key:
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type: string
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description: |-
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If this key is present, the event is a state event, and it will replace previous events
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with the same ``type`` and ``state_key`` in the room state.
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example: "my_key"
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content:
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type: object
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description: The content of the event.
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example: {"key": "value"}
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prev_events:
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type: array
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description: |-
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Event IDs and reference hashes for the most recent events in the room
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that the homeserver was aware of when it made this event.
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items:
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type: array
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maxItems: 2
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minItems: 2
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items:
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- type: string
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title: Event ID
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example: "$abc123:matrix.org"
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- type: object
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title: Event Hash
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example: {
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"sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
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}
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properties:
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sha256:
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type: string
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description: The event hash.
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example: Base64EncodedSha256HashesShouldBe43BytesLong
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required: ['sha256']
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depth:
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type: integer
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description: |-
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The maximum depth of the ``prev_events``, plus one. Must be less than the
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maximum value for an integer (2^63 - 1). If the room's depth is already at
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the limit, the depth must be set to the limit.
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example: 12
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auth_events:
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type: array
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description: |-
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Event IDs and reference hashes for the authorization events that would
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allow this event to be in the room.
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items:
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type: array
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maxItems: 2
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minItems: 2
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items:
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- type: string
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title: Event ID
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example: "$abc123:matrix.org"
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- type: object
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title: Event Hash
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example: {
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"sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
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}
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properties:
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sha256:
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type: string
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description: The event hash.
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example: Base64EncodedSha256HashesShouldBe43BytesLong
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required: ['sha256']
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redacts:
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type: string
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description: For redaction events, the ID of the event being redacted.
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example: "$def456:matrix.org"
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unsigned:
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type: object
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title: Example Unsigned Data
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description: |-
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Additional data added by the origin server but not covered by the ``signatures``. More
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keys than those defined here may be used.
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example: {"key": "value"}
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properties:
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age:
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type: integer
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description: The number of milliseconds that have passed since this message was sent.
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example: 4612
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replaces_state:
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type: string
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description: The event ID of the state event this event replaces.
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example: "$state_event:example.org"
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prev_sender:
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type: string
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description: The sender of the replaced state event.
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example: "@someone:example.org"
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prev_content:
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type: object
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description: The content of the replaced state event.
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example: {
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"membership": "join",
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"displayname": "Bob"
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}
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redacted_because:
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type: string
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description: A reason for why the event was redacted.
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example: "Inappropriate content"
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required:
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- event_id
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- room_id
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- sender
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- origin
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- origin_server_ts
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- type
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- content
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- prev_events
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- depth
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- auth_events
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{
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"$ref": "unsigned_pdu_base.json",
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"hashes": {
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"sha256": "thishashcoversallfieldsincasethisisredacted"
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},
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"signatures": {
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"example.com": {
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"ed25519:key_version:": "these86bytesofbase64signaturecoveressentialfieldsincludinghashessocancheckredactedpdus"
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}
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},
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"auth_events": [
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"$base64encodedeventid",
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"$adifferenteventid"
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],
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"prev_events": [
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"$base64encodedeventid",
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"$adifferenteventid"
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]
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}
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{
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"room_id": "!UcYsUzyxTGDxLBEvLy:example.org",
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"sender": "@alice:example.com",
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"origin": "example.com",
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"event_id": "$a4ecee13e2accdadf56c1025:example.com",
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"origin_server_ts": 1404838188000,
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"depth": 12,
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"auth_events": [
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[
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"$af232176:example.org",
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{"sha256": "abase64encodedsha256hashshouldbe43byteslong"}
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]
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],
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"type": "m.room.message",
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"prev_events": [
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[
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"$af232176:example.org",
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{"sha256": "abase64encodedsha256hashshouldbe43byteslong"}
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]
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],
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"content": {
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"key": "value"
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},
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"unsigned": {
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"age": 4612
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}
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"$ref": "unsigned_pdu_base.json",
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"event_id": "$a4ecee13e2accdadf56c1025:example.com"
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}
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{
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"room_id": "!UcYsUzyxTGDxLBEvLy:example.org",
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"sender": "@alice:example.com",
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"origin": "example.com",
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"origin_server_ts": 1404838188000,
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"depth": 12,
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"auth_events": [
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[
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"$af232176:example.org",
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{"sha256": "abase64encodedsha256hashshouldbe43byteslong"}
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]
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],
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"type": "m.room.message",
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"prev_events": [
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[
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"$af232176:example.org",
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{"sha256": "abase64encodedsha256hashshouldbe43byteslong"}
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]
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],
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"content": {
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"key": "value"
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},
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"unsigned": {
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"age": 4612
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}
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}
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@ -0,0 +1,121 @@
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.. Copyright 2018-2019 New Vector Ltd
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..
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.. Licensed under the Apache License, Version 2.0 (the "License");
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.. you may not use this file except in compliance with the License.
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.. You may obtain a copy of the License at
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..
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.. http://www.apache.org/licenses/LICENSE-2.0
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..
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.. Unless required by applicable law or agreed to in writing, software
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.. distributed under the License is distributed on an "AS IS" BASIS,
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.. WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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.. See the License for the specific language governing permissions and
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.. limitations under the License.
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Room Version 3
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==============
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This room version builds on `version 2 <v2.html>`_ with an improved event format.
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.. note:
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All requirements listed in this room version specification are scoped to rooms
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which actually use this room version. For example, a requirement of "all APIs must
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accept the new event format" does in fact apply to all APIs, but only so much as
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where the contextual room of the request is using this room version. Rooms using
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other room versions should not be affected by these sweeping requirements.
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Client considerations
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---------------------
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This room version changes the format for event IDs sent to clients. Clients should be
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aware that these event IDs may contain slashes and other potentially problematic
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characters. Clients should be treating event IDs as opaque identifiers and should not
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be attempting to parse them into a usable form, just like with other room versions.
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Clients should expect to see event IDs changed from the format of ``$randomstring:example.org``
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to something like ``$acR1l0raoZnm60CBwAVgqbZqoO/mYU81xysh1u7XcJk`` (note the lack of
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domain and the potentially problematic slash).
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Server implementation components
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--------------------------------
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.. WARNING::
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The information contained in this section is strictly for server implementors.
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Applications which use the Client-Server API are generally unaffected by the
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intricacies contained here. The section above regarding client considerations
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is the resource that Client-Server API use cases should reference.
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Room version 3 uses the state resolution algorithm defined in `room version 2 <v2.html>`_,
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and the event format defined here.
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Event IDs
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~~~~~~~~~
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.. admonition:: Rationale
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In other room versions (namely version 1 and 2) the event ID is a distinct field
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from the remainder of the event, which must be tracked as such. This leads to
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complications where servers receive multiple events with the same ID in either the
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same or different rooms where the server cannot easily keep track of which event it
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should be using. By removing the use of a dedicated event ID, servers are required
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to track the hashes on an event to determine its ID.
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The event ID is the `reference hash`_ of the event encoded using `Unpadded Base64`_,
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prefixed with ``$``. A resulting event ID using this approach should look similar to
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``$CD66HAED5npg6074c6pDtLKalHjVfYb2q4Q3LZgrW6o``.
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Event IDs should not be sent over federation to servers when the room uses
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this room version. On the receiving end of an event, the server should compute
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the relevant event ID for itself.
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Additionally, the ``auth_events`` and ``prev_events`` have had a format change
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compared to other room versions to make it easier to handle. Instead of a tuple
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of values, they are now plain lists of events.
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{{definition_ss_pdu_v3}}
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Changes to APIs
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~~~~~~~~~~~~~~~
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Due to the event ID being removed from the event, some APIs need to change. All
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APIs which currently accept an event ID must do so with the new format. Servers
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must append the calculated event ID to all events sent to clients where an event
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ID would normally be expected.
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Because the format of events has changed, servers must be aware of the room version
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where the event resides so that the server may parse and handle the event. The
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federation API has taken this concern into consideration by ensuring that servers
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are aware of (or can find) the room version during a request.
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Authorization rules for events
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The authorization rules for a given event have changed in this room version due
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to the change in event format:
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* The event no longer needs to be signed by the domain of the event ID (as there
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is no domain in the event ID), but still needs to be signed by the sender's
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domain.
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* In past room versions, redactions were only permitted to enter the DAG if the
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sender's domain matched the domain in the event ID being redacted, or the sender
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had appropriate permissions per the power levels. Due to servers now not being
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able to determine where an event came from during event authorization, redaction
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events are always accepted (provided the event is allowed by ``events`` and
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``events_default`` in the power levels). However, servers should not apply or send
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redactions to clients until both the redaction event and original event have been
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seen, and are valid. Servers should only apply redactions to events where the
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sender's domains match, or the sender of the redaction has the appropriate
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permissions per the power levels.
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The remaining rules are the same as `room version 1 <v1.html#authorization-rules>`_.
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.. _`Unpadded Base64`: ../../appendices.html#unpadded-base64
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.. _`Canonical JSON`: ../../appendices.html#canonical-json
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.. _`Signing Events`: ../../server_server/unstable.html#signing-events
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.. _`reference hash`: ../../server_server/unstable.html#reference-hashes
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