architex/lib/matrix_server/schema/event.ex

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defmodule MatrixServer.Event do
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use Ecto.Schema
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import Ecto.Query
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alias MatrixServer.{Repo, Room, Event, Account, EncodableMap, KeyServer}
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@primary_key {:event_id, :string, []}
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schema "events" do
field :type, :string
field :origin_server_ts, :utc_datetime_usec
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field :state_key, :string
field :sender, :string
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field :content, :map
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field :prev_events, {:array, :string}
field :auth_events, {:array, :string}
field :unsigned, :map
field :signatures, {:map, {:map, :string}}
field :hashes, {:map, :string}
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belongs_to :room, Room, type: :string
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end
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def new(%Room{id: room_id}, %Account{localpart: localpart}) do
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%Event{
room_id: room_id,
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sender: MatrixServer.get_mxid(localpart),
origin_server_ts: DateTime.utc_now(),
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prev_events: [],
auth_events: []
}
end
def create_room(
room,
%Account{localpart: localpart} = creator,
room_version
) do
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mxid = MatrixServer.get_mxid(localpart)
%Event{
new(room, creator)
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| type: "m.room.create",
state_key: "",
content: %{
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"creator" => mxid,
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"room_version" => room_version || MatrixServer.default_room_version()
}
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}
end
def join(room, %Account{localpart: localpart} = sender, auth_events) do
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mxid = MatrixServer.get_mxid(localpart)
%Event{
new(room, sender)
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| type: "m.room.member",
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state_key: mxid,
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content: %{
"membership" => "join"
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def power_levels(
room,
%Account{localpart: localpart} = sender,
auth_events
) do
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mxid = MatrixServer.get_mxid(localpart)
%Event{
new(room, sender)
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| type: "m.room.power_levels",
state_key: "",
content: %{
"ban" => 50,
"events" => %{},
"events_default" => 0,
"invite" => 50,
"kick" => 50,
"redact" => 50,
"state_default" => 50,
"users" => %{
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mxid => 50
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},
"users_default" => 0,
"notifications" => %{
"room" => 50
}
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def name(room, sender, name, auth_events) do
%Event{
new(room, sender)
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| type: "m.room.name",
state_key: "",
content: %{
"name" => name
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def topic(room, sender, topic, auth_events) do
%Event{
new(room, sender)
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| type: "m.room.topic",
state_key: "",
content: %{
"topic" => topic
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def join_rules(room, sender, join_rule, auth_events) do
%Event{
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new(room, sender)
| type: "m.room.join_rules",
state_key: "",
content: %{
"join_rule" => join_rule
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def history_visibility(room, sender, history_visibility, auth_events) do
%Event{
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new(room, sender)
| type: "m.room.history_visibility",
state_key: "",
content: %{
"history_visibility" => history_visibility
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
end
def guest_access(room, sender, guest_access, auth_events) do
%Event{
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new(room, sender)
| type: "m.room.guest_access",
state_key: "",
content: %{
"guest_access" => guest_access
},
auth_events: Enum.map(auth_events, & &1.event_id)
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}
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end
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def is_control_event(%Event{type: "m.room.power_levels", state_key: ""}), do: true
def is_control_event(%Event{type: "m.room.join_rules", state_key: ""}), do: true
def is_control_event(%Event{
type: "m.room.member",
state_key: state_key,
sender: sender,
content: %{membership: membership}
})
when sender != state_key and membership in ["leave", "ban"],
do: true
def is_control_event(_), do: false
def is_state_event(%Event{state_key: state_key}), do: state_key != nil
# Perform validations that can be done before state resolution.
# For example checking the domain of the sender.
# We assume that required keys, as well as in the content, is already validated.
# Rule 1.4 is left to changeset validation.
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def prevalidate(%Event{
type: "m.room.create",
prev_events: prev_events,
auth_events: auth_events,
room_id: room_id,
sender: sender
}) do
# TODO: error check on domains?
# TODO: rule 1.3
# Check rules: 1.1, 1.2
prev_events == [] and
auth_events == [] and
MatrixServer.get_domain(sender) == MatrixServer.get_domain(room_id)
end
def prevalidate(%Event{auth_events: auth_event_ids, prev_events: prev_event_ids} = event) do
prev_events =
Event
|> where([e], e.event_id in ^prev_event_ids)
|> Repo.all()
auth_events =
Event
|> where([e], e.event_id in ^auth_event_ids)
|> Repo.all()
state_pairs = Enum.map(auth_events, &{&1.type, &1.state_key})
# Check rules: 2.1, 2.2, 3
length(auth_events) == length(auth_event_ids) and
length(prev_events) == length(prev_event_ids) and
not MatrixServer.has_duplicates?(state_pairs) and
valid_auth_events?(event, auth_events) and
Enum.find_value(state_pairs, &(&1 == {"m.room.create", ""})) and
do_prevalidate(event, auth_events, prev_events)
end
# Rule 4.1 is left to changeset validation.
defp do_prevalidate(%Event{type: "m.room.aliases", sender: sender, state_key: state_key}, _, _) do
# Check rule: 4.2
MatrixServer.get_domain(sender) == MatrixServer.get_domain(state_key)
end
# Rule 5.1 is left to changeset validation.
# Rules 5.2.3, 5.2.4, 5.2.5 is left to state resolution.
# Check rule: 5.2.1
defp do_prevalidate(
%Event{type: "m.room.member", content: %{"membership" => "join"}, sender: sender},
_,
[%Event{type: "m.room.create", state_key: sender}]
),
do: true
# Check rule: 5.2.2
defp do_prevalidate(
%Event{
type: "m.room.member",
content: %{"membership" => "join"},
sender: sender,
state_key: state_key
},
_,
_
)
when sender != state_key,
do: false
# All other rules will be checked during state resolution.
defp do_prevalidate(_, _, _), do: true
defp valid_auth_events?(
%Event{type: type, sender: sender, state_key: state_key, content: content},
auth_events
) do
Enum.all?(auth_events, fn
%Event{type: "m.room.create", state_key: ""} ->
true
%Event{type: "m.room.power_levels", state_key: ""} ->
true
%Event{type: "m.room.member", state_key: ^sender} ->
true
%Event{type: auth_type, state_key: auth_state_key} ->
if type == "m.room.member" do
%{"membership" => membership} = content
(auth_type == "m.room.member" and auth_state_key == state_key) or
(membership in ["join", "invite"] and auth_type == "m.room.join_rules" and
auth_state_key == "") or
(membership == "invite" and auth_type == "m.room.third_party_invite" and
auth_state_key == "")
else
false
end
end)
end
defp calculate_content_hash(event) do
m =
event
|> MatrixServer.to_serializable_map()
|> Map.drop([:unsigned, :signature, :hashes])
|> EncodableMap.from_map()
with {:ok, json} <- Jason.encode(m) do
{:ok, :crypto.hash(:sha256, json)}
end
end
defp redact(%Event{type: type, content: content} = event) do
redacted_event =
event
|> MatrixServer.to_serializable_map()
|> Map.take([
:event_id,
:type,
:room_id,
:sender,
:state_key,
:content,
:hashes,
:signatures,
:depth,
:prev_events,
:prev_state,
:auth_events,
:origin,
:origin_server_ts,
:membership
])
%{redacted_event | content: redact_content(type, content)}
end
defp redact_content("m.room.member", content), do: Map.take(content, ["membership"])
defp redact_content("m.room.create", content), do: Map.take(content, ["creator"])
defp redact_content("m.room.join_rules", content), do: Map.take(content, ["join_rule"])
defp redact_content("m.room.aliases", content), do: Map.take(content, ["aliases"])
defp redact_content("m.room.history_visibility", content),
do: Map.take(content, ["history_visibility"])
defp redact_content("m.room.power_levels", content),
do:
Map.take(content, [
"ban",
"events",
"events_default",
"kick",
"redact",
"state_default",
"users",
"users_default"
])
defp redact_content(_, _), do: %{}
# Adds content hash, adds signature and calculates event id.
def post_process(event) do
with {:ok, content_hash} <- calculate_content_hash(event) do
encoded_hash = MatrixServer.encode_unpadded_base64(content_hash)
event = %Event{event | hashes: %{"sha256" => encoded_hash}}
with {:ok, sig, key_id} <- KeyServer.sign_object(redact(event)) do
event = %Event{event | signatures: %{MatrixServer.server_name() => %{key_id => sig}}}
with {:ok, event} <- set_event_id(event) do
{:ok, event}
end
end
end
end
def set_event_id(event) do
with {:ok, event_id} <- generate_event_id(event) do
{:ok, %Event{event | event_id: event_id}}
end
end
defp generate_event_id(event) do
with {:ok, hash} <- calculate_reference_hash(event) do
{:ok, "$" <> MatrixServer.encode_url_safe_base64(hash)}
end
end
defp calculate_reference_hash(event) do
redacted_event =
event
|> redact()
|> Map.drop([:unsigned, :signature, :age_ts])
with {:ok, json} <- MatrixServer.encode_canonical_json(redacted_event) do
{:ok, :crypto.hash(:sha256, json)}
end
end
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end