membership.rs

use std::{
	collections::{hash_map::Entry, BTreeMap, HashMap, HashSet},
	sync::Arc,
	time::{Duration, Instant},
};

use ruma::{
	api::{
		client::{
			error::ErrorKind,
			membership::{
				ban_user, forget_room, get_member_events, invite_user, join_room_by_id, join_room_by_id_or_alias,
				joined_members, joined_rooms, kick_user, leave_room, unban_user, ThirdPartySigned,
			},
		},
		federation::{self, membership::create_invite},
	},
	canonical_json::to_canonical_value,
	events::{
		room::{
			join_rules::{AllowRule, JoinRule, RoomJoinRulesEventContent},
			member::{MembershipState, RoomMemberEventContent},
			power_levels::RoomPowerLevelsEventContent,
		},
		StateEventType, TimelineEventType,
	},
	serde::Base64,
	state_res, CanonicalJsonObject, CanonicalJsonValue, EventId, OwnedEventId, OwnedRoomId, OwnedServerName,
	OwnedUserId, RoomId, RoomVersionId, UserId,
};
use serde_json::value::{to_raw_value, RawValue as RawJsonValue};
use tokio::sync::RwLock;
use tracing::{debug, error, info, warn};

use super::get_alias_helper;
use crate::{
	service::pdu::{gen_event_id_canonical_json, PduBuilder},
	services, utils, Error, PduEvent, Result, Ruma,
};

/// # `POST /_matrix/client/r0/rooms/{roomId}/join`
///
/// Tries to join the sender user into a room.
///
/// - If the server knowns about this room: creates the join event and does auth
///   rules locally
/// - If the server does not know about the room: asks other servers over
///   federation
pub async fn join_room_by_id_route(body: Ruma<join_room_by_id::v3::Request>) -> Result<join_room_by_id::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	if services().rooms.metadata.is_banned(&body.room_id)? && !services().users.is_admin(sender_user)? {
		return Err(Error::BadRequest(
			ErrorKind::Forbidden,
			"This room is banned on this homeserver.",
		));
	}

	let mut servers = Vec::new(); // There is no body.server_name for /roomId/join
	servers.extend(
		services()
			.rooms
			.state_cache
			.invite_state(sender_user, &body.room_id)?
			.unwrap_or_default()
			.iter()
			.filter_map(|event| serde_json::from_str(event.json().get()).ok())
			.filter_map(|event: serde_json::Value| event.get("sender").cloned())
			.filter_map(|sender| sender.as_str().map(ToOwned::to_owned))
			.filter_map(|sender| UserId::parse(sender).ok())
			.map(|user| user.server_name().to_owned()),
	);

	// server names being permanently attached to room IDs may be potentally removed
	// in the future (see MSC4051). for future compatibility with this, and just
	// because it makes sense, we shouldn't fail if the room ID doesn't have a
	// server name with it and just use at least the server name from the initial
	// invite above
	if let Some(server) = body.room_id.server_name() {
		servers.push(server.into());
	}

	join_room_by_id_helper(
		body.sender_user.as_deref(),
		&body.room_id,
		body.reason.clone(),
		&servers,
		body.third_party_signed.as_ref(),
	)
	.await
}

/// # `POST /_matrix/client/r0/join/{roomIdOrAlias}`
///
/// Tries to join the sender user into a room.
///
/// - If the server knowns about this room: creates the join event and does auth
///   rules locally
/// - If the server does not know about the room: asks other servers over
///   federation
pub async fn join_room_by_id_or_alias_route(
	body: Ruma<join_room_by_id_or_alias::v3::Request>,
) -> Result<join_room_by_id_or_alias::v3::Response> {
	let sender_user = body.sender_user.as_deref().expect("user is authenticated");
	let body = body.body;

	let (servers, room_id) = match OwnedRoomId::try_from(body.room_id_or_alias) {
		Ok(room_id) => {
			if services().rooms.metadata.is_banned(&room_id)? && !services().users.is_admin(sender_user)? {
				return Err(Error::BadRequest(
					ErrorKind::Forbidden,
					"This room is banned on this homeserver.",
				));
			}

			let mut servers = body.server_name.clone();
			servers.extend(
				services()
					.rooms
					.state_cache
					.invite_state(sender_user, &room_id)?
					.unwrap_or_default()
					.iter()
					.filter_map(|event| serde_json::from_str(event.json().get()).ok())
					.filter_map(|event: serde_json::Value| event.get("sender").cloned())
					.filter_map(|sender| sender.as_str().map(ToOwned::to_owned))
					.filter_map(|sender| UserId::parse(sender).ok())
					.map(|user| user.server_name().to_owned()),
			);

			// server names being permanently attached to room IDs may be potentally removed
			// in the future (see MSC4051). for future compatibility with this, and just
			// because it makes sense, we shouldn't fail if the room ID doesn't have a
			// server name with it and just use at least the server name from the initial
			// invite above
			if let Some(server) = room_id.server_name() {
				servers.push(server.into());
			}

			(servers, room_id)
		},
		Err(room_alias) => {
			let response = get_alias_helper(room_alias).await?;

			if services().rooms.metadata.is_banned(&response.room_id)? && !services().users.is_admin(sender_user)? {
				return Err(Error::BadRequest(
					ErrorKind::Forbidden,
					"This room is banned on this homeserver.",
				));
			}

			(response.servers, response.room_id)
		},
	};

	let join_room_response = join_room_by_id_helper(
		Some(sender_user),
		&room_id,
		body.reason.clone(),
		&servers,
		body.third_party_signed.as_ref(),
	)
	.await?;

	Ok(join_room_by_id_or_alias::v3::Response {
		room_id: join_room_response.room_id,
	})
}

/// # `POST /_matrix/client/v3/rooms/{roomId}/leave`
///
/// Tries to leave the sender user from a room.
///
/// - This should always work if the user is currently joined.
pub async fn leave_room_route(body: Ruma<leave_room::v3::Request>) -> Result<leave_room::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	leave_room(sender_user, &body.room_id, body.reason.clone()).await?;

	Ok(leave_room::v3::Response::new())
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/invite`
///
/// Tries to send an invite event into the room.
pub async fn invite_user_route(body: Ruma<invite_user::v3::Request>) -> Result<invite_user::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	if !services().users.is_admin(sender_user)? && services().globals.block_non_admin_invites() {
		info!(
			"User {sender_user} is not an admin and attempted to send an invite to room {}",
			&body.room_id
		);
		return Err(Error::BadRequest(
			ErrorKind::Forbidden,
			"Invites are not allowed on this server.",
		));
	}

	if services().rooms.metadata.is_banned(&body.room_id)? && !services().users.is_admin(sender_user)? {
		info!(
			"Local user {} who is not an admin attempted to send an invite for banned room {}.",
			&sender_user, &body.room_id
		);
		return Err(Error::BadRequest(
			ErrorKind::Forbidden,
			"This room is banned on this homeserver.",
		));
	}

	if let invite_user::v3::InvitationRecipient::UserId {
		user_id,
	} = &body.recipient
	{
		invite_helper(sender_user, user_id, &body.room_id, body.reason.clone(), false).await?;
		Ok(invite_user::v3::Response {})
	} else {
		Err(Error::BadRequest(ErrorKind::NotFound, "User not found."))
	}
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/kick`
///
/// Tries to send a kick event into the room.
pub async fn kick_user_route(body: Ruma<kick_user::v3::Request>) -> Result<kick_user::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	let mut event: RoomMemberEventContent = serde_json::from_str(
		services()
			.rooms
			.state_accessor
			.room_state_get(&body.room_id, &StateEventType::RoomMember, body.user_id.as_ref())?
			.ok_or(Error::BadRequest(
				ErrorKind::BadState,
				"Cannot kick member that's not in the room.",
			))?
			.content
			.get(),
	)
	.map_err(|_| Error::bad_database("Invalid member event in database."))?;

	event.membership = MembershipState::Leave;
	event.reason.clone_from(&body.reason);

	let mutex_state =
		Arc::clone(services().globals.roomid_mutex_state.write().await.entry(body.room_id.clone()).or_default());
	let state_lock = mutex_state.lock().await;

	services()
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder {
				event_type: TimelineEventType::RoomMember,
				content: to_raw_value(&event).expect("event is valid, we just created it"),
				unsigned: None,
				state_key: Some(body.user_id.to_string()),
				redacts: None,
			},
			sender_user,
			&body.room_id,
			&state_lock,
		)
		.await?;

	drop(state_lock);

	Ok(kick_user::v3::Response::new())
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/ban`
///
/// Tries to send a ban event into the room.
pub async fn ban_user_route(body: Ruma<ban_user::v3::Request>) -> Result<ban_user::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	let event = services()
		.rooms
		.state_accessor
		.room_state_get(&body.room_id, &StateEventType::RoomMember, body.user_id.as_ref())?
		.map_or(
			Ok(RoomMemberEventContent {
				membership: MembershipState::Ban,
				displayname: services().users.displayname(&body.user_id)?,
				avatar_url: services().users.avatar_url(&body.user_id)?,
				is_direct: None,
				third_party_invite: None,
				blurhash: services().users.blurhash(&body.user_id)?,
				reason: body.reason.clone(),
				join_authorized_via_users_server: None,
			}),
			|event| {
				serde_json::from_str(event.content.get())
					.map(|event: RoomMemberEventContent| RoomMemberEventContent {
						membership: MembershipState::Ban,
						displayname: services().users.displayname(&body.user_id).unwrap_or_default(),
						avatar_url: services().users.avatar_url(&body.user_id).unwrap_or_default(),
						blurhash: services().users.blurhash(&body.user_id).unwrap_or_default(),
						reason: body.reason.clone(),
						..event
					})
					.map_err(|_| Error::bad_database("Invalid member event in database."))
			},
		)?;

	let mutex_state =
		Arc::clone(services().globals.roomid_mutex_state.write().await.entry(body.room_id.clone()).or_default());
	let state_lock = mutex_state.lock().await;

	services()
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder {
				event_type: TimelineEventType::RoomMember,
				content: to_raw_value(&event).expect("event is valid, we just created it"),
				unsigned: None,
				state_key: Some(body.user_id.to_string()),
				redacts: None,
			},
			sender_user,
			&body.room_id,
			&state_lock,
		)
		.await?;

	drop(state_lock);

	Ok(ban_user::v3::Response::new())
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/unban`
///
/// Tries to send an unban event into the room.
pub async fn unban_user_route(body: Ruma<unban_user::v3::Request>) -> Result<unban_user::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	let mut event: RoomMemberEventContent = serde_json::from_str(
		services()
			.rooms
			.state_accessor
			.room_state_get(&body.room_id, &StateEventType::RoomMember, body.user_id.as_ref())?
			.ok_or(Error::BadRequest(ErrorKind::BadState, "Cannot unban a user who is not banned."))?
			.content
			.get(),
	)
	.map_err(|_| Error::bad_database("Invalid member event in database."))?;

	event.membership = MembershipState::Leave;
	event.reason.clone_from(&body.reason);

	let mutex_state =
		Arc::clone(services().globals.roomid_mutex_state.write().await.entry(body.room_id.clone()).or_default());
	let state_lock = mutex_state.lock().await;

	services()
		.rooms
		.timeline
		.build_and_append_pdu(
			PduBuilder {
				event_type: TimelineEventType::RoomMember,
				content: to_raw_value(&event).expect("event is valid, we just created it"),
				unsigned: None,
				state_key: Some(body.user_id.to_string()),
				redacts: None,
			},
			sender_user,
			&body.room_id,
			&state_lock,
		)
		.await?;

	drop(state_lock);

	Ok(unban_user::v3::Response::new())
}

/// # `POST /_matrix/client/v3/rooms/{roomId}/forget`
///
/// Forgets about a room.
///
/// - If the sender user currently left the room: Stops sender user from
///   receiving information about the room
///
/// Note: Other devices of the user have no way of knowing the room was
/// forgotten, so this has to be called from every device
pub async fn forget_room_route(body: Ruma<forget_room::v3::Request>) -> Result<forget_room::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	services().rooms.state_cache.forget(&body.room_id, sender_user)?;

	Ok(forget_room::v3::Response::new())
}

/// # `POST /_matrix/client/r0/joined_rooms`
///
/// Lists all rooms the user has joined.
pub async fn joined_rooms_route(body: Ruma<joined_rooms::v3::Request>) -> Result<joined_rooms::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	Ok(joined_rooms::v3::Response {
		joined_rooms: services()
			.rooms
			.state_cache
			.rooms_joined(sender_user)
			.filter_map(std::result::Result::ok)
			.collect(),
	})
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/members`
///
/// Lists all joined users in a room (TODO: at a specific point in time, with a
/// specific membership).
///
/// - Only works if the user is currently joined
pub async fn get_member_events_route(
	body: Ruma<get_member_events::v3::Request>,
) -> Result<get_member_events::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	if !services().rooms.state_accessor.user_can_see_state_events(sender_user, &body.room_id)? {
		return Err(Error::BadRequest(
			ErrorKind::Forbidden,
			"You don't have permission to view this room.",
		));
	}

	Ok(get_member_events::v3::Response {
		chunk: services()
			.rooms
			.state_accessor
			.room_state_full(&body.room_id)
			.await?
			.iter()
			.filter(|(key, _)| key.0 == StateEventType::RoomMember)
			.map(|(_, pdu)| pdu.to_member_event())
			.collect(),
	})
}

/// # `POST /_matrix/client/r0/rooms/{roomId}/joined_members`
///
/// Lists all members of a room.
///
/// - The sender user must be in the room
/// - TODO: An appservice just needs a puppet joined
pub async fn joined_members_route(body: Ruma<joined_members::v3::Request>) -> Result<joined_members::v3::Response> {
	let sender_user = body.sender_user.as_ref().expect("user is authenticated");

	if !services().rooms.state_accessor.user_can_see_state_events(sender_user, &body.room_id)? {
		return Err(Error::BadRequest(
			ErrorKind::Forbidden,
			"You don't have permission to view this room.",
		));
	}

	let mut joined = BTreeMap::new();
	for user_id in services().rooms.state_cache.room_members(&body.room_id).filter_map(std::result::Result::ok) {
		let display_name = services().users.displayname(&user_id)?;
		let avatar_url = services().users.avatar_url(&user_id)?;

		joined.insert(
			user_id,
			joined_members::v3::RoomMember {
				display_name,
				avatar_url,
			},
		);
	}

	Ok(joined_members::v3::Response {
		joined,
	})
}

pub(crate) async fn join_room_by_id_helper(
	sender_user: Option<&UserId>, room_id: &RoomId, reason: Option<String>, servers: &[OwnedServerName],
	_third_party_signed: Option<&ThirdPartySigned>,
) -> Result<join_room_by_id::v3::Response> {
	let sender_user = sender_user.expect("user is authenticated");

	let mutex_state =
		Arc::clone(services().globals.roomid_mutex_state.write().await.entry(room_id.to_owned()).or_default());
	let state_lock = mutex_state.lock().await;

	// Ask a remote server if we are not participating in this room
	if !services().rooms.state_cache.server_in_room(services().globals.server_name(), room_id)? {
		info!("Joining {room_id} over federation.");

		let (make_join_response, remote_server) = make_join_request(sender_user, room_id, servers).await?;

		info!("make_join finished");

		let room_version_id = match make_join_response.room_version {
			Some(room_version) if services().globals.supported_room_versions().contains(&room_version) => room_version,
			_ => return Err(Error::BadServerResponse("Room version is not supported")),
		};

		let mut join_event_stub: CanonicalJsonObject = serde_json::from_str(make_join_response.event.get())
			.map_err(|_| Error::BadServerResponse("Invalid make_join event json received from server."))?;

		let join_authorized_via_users_server = join_event_stub
			.get("content")
			.map(|s| s.as_object()?.get("join_authorised_via_users_server")?.as_str())
			.and_then(|s| OwnedUserId::try_from(s.unwrap_or_default()).ok());

		// TODO: Is origin needed?
		join_event_stub.insert(
			"origin".to_owned(),
			CanonicalJsonValue::String(services().globals.server_name().as_str().to_owned()),
		);
		join_event_stub.insert(
			"origin_server_ts".to_owned(),
			CanonicalJsonValue::Integer(
				utils::millis_since_unix_epoch().try_into().expect("Timestamp is valid js_int value"),
			),
		);
		join_event_stub.insert(
			"content".to_owned(),
			to_canonical_value(RoomMemberEventContent {
				membership: MembershipState::Join,
				displayname: services().users.displayname(sender_user)?,
				avatar_url: services().users.avatar_url(sender_user)?,
				is_direct: None,
				third_party_invite: None,
				blurhash: services().users.blurhash(sender_user)?,
				reason,
				join_authorized_via_users_server: join_authorized_via_users_server.clone(),
			})
			.expect("event is valid, we just created it"),
		);

		// We don't leave the event id in the pdu because that's only allowed in v1 or
		// v2 rooms
		join_event_stub.remove("event_id");

		// In order to create a compatible ref hash (EventID) the `hashes` field needs
		// to be present
		ruma::signatures::hash_and_sign_event(
			services().globals.server_name().as_str(),
			services().globals.keypair(),
			&mut join_event_stub,
			&room_version_id,
		)
		.expect("event is valid, we just created it");

		// Generate event id
		let event_id = format!(
			"${}",
			ruma::signatures::reference_hash(&join_event_stub, &room_version_id)
				.expect("ruma can calculate reference hashes")
		);
		let event_id = <&EventId>::try_from(event_id.as_str()).expect("ruma's reference hashes are valid event ids");

		// Add event_id back
		join_event_stub.insert("event_id".to_owned(), CanonicalJsonValue::String(event_id.as_str().to_owned()));

		// It has enough fields to be called a proper event now
		let mut join_event = join_event_stub;

		info!("Asking {remote_server} for send_join in room {room_id}");
		let send_join_response = services()
			.sending
			.send_federation_request(
				&remote_server,
				federation::membership::create_join_event::v2::Request {
					room_id: room_id.to_owned(),
					event_id: event_id.to_owned(),
					pdu: PduEvent::convert_to_outgoing_federation_event(join_event.clone()),
					omit_members: false,
				},
			)
			.await?;

		info!("send_join finished");

		if join_authorized_via_users_server.is_some() {
			match &room_version_id {
				RoomVersionId::V1
				| RoomVersionId::V2
				| RoomVersionId::V3
				| RoomVersionId::V4
				| RoomVersionId::V5
				| RoomVersionId::V6
				| RoomVersionId::V7 => {
					warn!(
						"Found `join_authorised_via_users_server` but room {} is version {}. Ignoring.",
						room_id, &room_version_id
					);
				},
				// only room versions 8 and above using `join_authorized_via_users_server` (restricted joins) need to
				// validate and send signatures
				RoomVersionId::V8 | RoomVersionId::V9 | RoomVersionId::V10 | RoomVersionId::V11 => {
					if let Some(signed_raw) = &send_join_response.room_state.event {
						info!(
							"There is a signed event. This room is probably using restricted joins. Adding signature \
							 to our event"
						);
						let (signed_event_id, signed_value) =
							match gen_event_id_canonical_json(signed_raw, &room_version_id) {
								Ok(t) => t,
								Err(_) => {
									// Event could not be converted to canonical json
									return Err(Error::BadRequest(
										ErrorKind::InvalidParam,
										"Could not convert event to canonical json.",
									));
								},
							};

						if signed_event_id != event_id {
							return Err(Error::BadRequest(
								ErrorKind::InvalidParam,
								"Server sent event with wrong event id",
							));
						}

						match signed_value["signatures"]
							.as_object()
							.ok_or(Error::BadRequest(
								ErrorKind::InvalidParam,
								"Server sent invalid signatures type",
							))
							.and_then(|e| {
								e.get(remote_server.as_str()).ok_or(Error::BadRequest(
									ErrorKind::InvalidParam,
									"Server did not send its signature",
								))
							}) {
							Ok(signature) => {
								join_event
									.get_mut("signatures")
									.expect("we created a valid pdu")
									.as_object_mut()
									.expect("we created a valid pdu")
									.insert(remote_server.to_string(), signature.clone());
							},
							Err(e) => {
								warn!(
									"Server {remote_server} sent invalid signature in sendjoin signatures for event \
									 {signed_value:?}: {e:?}",
								);
							},
						}
					}
				},
				_ => {
					warn!(
						"Unexpected or unsupported room version {} for room {}",
						&room_version_id, room_id
					);
					return Err(Error::BadRequest(
						ErrorKind::BadJson,
						"Unexpected or unsupported room version found",
					));
				},
			}
		}

		services().rooms.short.get_or_create_shortroomid(room_id)?;

		info!("Parsing join event");
		let parsed_join_pdu = PduEvent::from_id_val(event_id, join_event.clone())
			.map_err(|_| Error::BadServerResponse("Invalid join event PDU."))?;

		let mut state = HashMap::new();
		let pub_key_map = RwLock::new(BTreeMap::new());

		info!("Fetching join signing keys");
		services()
			.rooms
			.event_handler
			.fetch_join_signing_keys(&send_join_response, &room_version_id, &pub_key_map)
			.await?;

		info!("Going through send_join response room_state");
		for result in send_join_response
			.room_state
			.state
			.iter()
			.map(|pdu| validate_and_add_event_id(pdu, &room_version_id, &pub_key_map))
		{
			let (event_id, value) = match result.await {
				Ok(t) => t,
				Err(_) => continue,
			};

			let pdu = PduEvent::from_id_val(&event_id, value.clone()).map_err(|e| {
				warn!("Invalid PDU in send_join response: {} {:?}", e, value);
				Error::BadServerResponse("Invalid PDU in send_join response.")
			})?;

			services().rooms.outlier.add_pdu_outlier(&event_id, &value)?;
			if let Some(state_key) = &pdu.state_key {
				let shortstatekey =
					services().rooms.short.get_or_create_shortstatekey(&pdu.kind.to_string().into(), state_key)?;
				state.insert(shortstatekey, pdu.event_id.clone());
			}
		}

		info!("Going through send_join response auth_chain");
		for result in send_join_response
			.room_state
			.auth_chain
			.iter()
			.map(|pdu| validate_and_add_event_id(pdu, &room_version_id, &pub_key_map))
		{
			let (event_id, value) = match result.await {
				Ok(t) => t,
				Err(_) => continue,
			};

			services().rooms.outlier.add_pdu_outlier(&event_id, &value)?;
		}

		info!("Running send_join auth check");

		let auth_check = state_res::event_auth::auth_check(
			&state_res::RoomVersion::new(&room_version_id).expect("room version is supported"),
			&parsed_join_pdu,
			None::<PduEvent>, // TODO: third party invite
			|k, s| {
				services()
					.rooms
					.timeline
					.get_pdu(
						state
							.get(&services().rooms.short.get_or_create_shortstatekey(&k.to_string().into(), s).ok()?)?,
					)
					.ok()?
			},
		)
		.map_err(|e| {
			warn!("Auth check failed: {e}");
			Error::BadRequest(ErrorKind::InvalidParam, "Auth check failed")
		})?;

		if !auth_check {
			return Err(Error::BadRequest(ErrorKind::InvalidParam, "Auth check failed"));
		}

		info!("Saving state from send_join");
		let (statehash_before_join, new, removed) = services().rooms.state_compressor.save_state(
			room_id,
			Arc::new(
				state
					.into_iter()
					.map(|(k, id)| services().rooms.state_compressor.compress_state_event(k, &id))
					.collect::<Result<_>>()?,
			),
		)?;

		services().rooms.state.force_state(room_id, statehash_before_join, new, removed, &state_lock).await?;

		info!("Updating joined counts for new room");
		services().rooms.state_cache.update_joined_count(room_id)?;

		// We append to state before appending the pdu, so we don't have a moment in
		// time with the pdu without it's state. This is okay because append_pdu can't
		// fail.
		let statehash_after_join = services().rooms.state.append_to_state(&parsed_join_pdu)?;

		info!("Appending new room join event");
		services()
			.rooms
			.timeline
			.append_pdu(
				&parsed_join_pdu,
				join_event,
				vec![(*parsed_join_pdu.event_id).to_owned()],
				&state_lock,
			)
			.await?;

		info!("Setting final room state for new room");
		// We set the room state after inserting the pdu, so that we never have a moment
		// in time where events in the current room state do not exist
		services().rooms.state.set_room_state(room_id, statehash_after_join, &state_lock)?;
	} else {
		info!("We can join locally");

		let join_rules_event =
			services().rooms.state_accessor.room_state_get(room_id, &StateEventType::RoomJoinRules, "")?;
		let power_levels_event =
			services().rooms.state_accessor.room_state_get(room_id, &StateEventType::RoomPowerLevels, "")?;

		let join_rules_event_content: Option<RoomJoinRulesEventContent> = join_rules_event
			.as_ref()
			.map(|join_rules_event| {
				serde_json::from_str(join_rules_event.content.get()).map_err(|e| {
					warn!("Invalid join rules event: {}", e);
					Error::bad_database("Invalid join rules event in db.")
				})
			})
			.transpose()?;
		let power_levels_event_content: Option<RoomPowerLevelsEventContent> = power_levels_event
			.as_ref()
			.map(|power_levels_event| {
				serde_json::from_str(power_levels_event.content.get()).map_err(|e| {
					warn!("Invalid power levels event: {}", e);
					Error::bad_database("Invalid power levels event in db.")
				})
			})
			.transpose()?;

		let restriction_rooms = match join_rules_event_content {
			Some(RoomJoinRulesEventContent {
				join_rule: JoinRule::Restricted(restricted) | JoinRule::KnockRestricted(restricted),
			}) => restricted
				.allow
				.into_iter()
				.filter_map(|a| match a {
					AllowRule::RoomMembership(r) => Some(r.room_id),
					_ => None,
				})
				.collect(),
			_ => Vec::new(),
		};

		let authorized_user = restriction_rooms
			.iter()
			.find_map(|restriction_room_id| {
				if !services().rooms.state_cache.is_joined(sender_user, restriction_room_id).ok()? {
					return None;
				}
				let authorized_user = power_levels_event_content
					.as_ref()
					.and_then(|c| {
						c.users
							.iter()
							.filter(|(uid, i)| {
								uid.server_name() == services().globals.server_name()
									&& **i > ruma::int!(0) && services()
									.rooms
									.state_cache
									.is_joined(uid, restriction_room_id)
									.unwrap_or(false)
							})
							.max_by_key(|(_, i)| *i)
							.map(|(u, _)| u.to_owned())
					})
					.or_else(|| {
						// TODO: Check here if user is actually allowed to invite. Currently the auth
						// check will just fail in this case.
						services()
							.rooms
							.state_cache
							.room_members(restriction_room_id)
							.filter_map(std::result::Result::ok)
							.find(|uid| uid.server_name() == services().globals.server_name())
					});
				Some(authorized_user)
			})
			.flatten();

		let event = RoomMemberEventContent {
			membership: MembershipState::Join,
			displayname: services().users.displayname(sender_user)?,
			avatar_url: services().users.avatar_url(sender_user)?,
			is_direct: None,
			third_party_invite: None,
			blurhash: services().users.blurhash(sender_user)?,
			reason: reason.clone(),
			join_authorized_via_users_server: authorized_user,
		};

		// Try normal join first
		let error = match services()
			.rooms
			.timeline
			.build_and_append_pdu(
				PduBuilder {
					event_type: TimelineEventType::RoomMember,
					content: to_raw_value(&event).expect("event is valid, we just created it"),
					unsigned: None,
					state_key: Some(sender_user.to_string()),
					redacts: None,
				},
				sender_user,
				room_id,
				&state_lock,
			)
			.await
		{
			Ok(_event_id) => return Ok(join_room_by_id::v3::Response::new(room_id.to_owned())),
			Err(e) => e,
		};

		if !restriction_rooms.is_empty()
			&& servers.iter().filter(|s| *s != services().globals.server_name()).count() > 0
		{
			info!(
				"We couldn't do the join locally, maybe federation can help to satisfy the restricted join \
				 requirements"
			);
			let (make_join_response, remote_server) = make_join_request(sender_user, room_id, servers).await?;

			let room_version_id = match make_join_response.room_version {
				Some(room_version_id) if services().globals.supported_room_versions().contains(&room_version_id) => {
					room_version_id
				},
				_ => return Err(Error::BadServerResponse("Room version is not supported")),
			};
			let mut join_event_stub: CanonicalJsonObject = serde_json::from_str(make_join_response.event.get())
				.map_err(|_| Error::BadServerResponse("Invalid make_join event json received from server."))?;
			let join_authorized_via_users_server = join_event_stub
				.get("content")
				.map(|s| s.as_object()?.get("join_authorised_via_users_server")?.as_str())
				.and_then(|s| OwnedUserId::try_from(s.unwrap_or_default()).ok());
			// TODO: Is origin needed?
			join_event_stub.insert(
				"origin".to_owned(),
				CanonicalJsonValue::String(services().globals.server_name().as_str().to_owned()),
			);
			join_event_stub.insert(
				"origin_server_ts".to_owned(),
				CanonicalJsonValue::Integer(
					utils::millis_since_unix_epoch().try_into().expect("Timestamp is valid js_int value"),
				),
			);
			join_event_stub.insert(
				"content".to_owned(),
				to_canonical_value(RoomMemberEventContent {
					membership: MembershipState::Join,
					displayname: services().users.displayname(sender_user)?,
					avatar_url: services().users.avatar_url(sender_user)?,
					is_direct: None,
					third_party_invite: None,
					blurhash: services().users.blurhash(sender_user)?,
					reason,
					join_authorized_via_users_server,
				})
				.expect("event is valid, we just created it"),
			);

			// We don't leave the event id in the pdu because that's only allowed in v1 or
			// v2 rooms
			join_event_stub.remove("event_id");

			// In order to create a compatible ref hash (EventID) the `hashes` field needs
			// to be present
			ruma::signatures::hash_and_sign_event(
				services().globals.server_name().as_str(),
				services().globals.keypair(),
				&mut join_event_stub,
				&room_version_id,
			)
			.expect("event is valid, we just created it");

			// Generate event id
			let event_id = format!(
				"${}",
				ruma::signatures::reference_hash(&join_event_stub, &room_version_id)
					.expect("ruma can calculate reference hashes")
			);
			let event_id =
				<&EventId>::try_from(event_id.as_str()).expect("ruma's reference hashes are valid event ids");

			// Add event_id back
			join_event_stub.insert("event_id".to_owned(), CanonicalJsonValue::String(event_id.as_str().to_owned()));

			// It has enough fields to be called a proper event now
			let join_event = join_event_stub;

			let send_join_response = services()
				.sending
				.send_federation_request(
					&remote_server,
					federation::membership::create_join_event::v2::Request {
						room_id: room_id.to_owned(),
						event_id: event_id.to_owned(),
						pdu: PduEvent::convert_to_outgoing_federation_event(join_event.clone()),
						omit_members: false,
					},
				)
				.await?;

			if let Some(signed_raw) = send_join_response.room_state.event {
				let (signed_event_id, signed_value) = match gen_event_id_canonical_json(&signed_raw, &room_version_id) {
					Ok(t) => t,
					Err(_) => {
						// Event could not be converted to canonical json
						return Err(Error::BadRequest(
							ErrorKind::InvalidParam,
							"Could not convert event to canonical json.",
						));
					},
				};

				if signed_event_id != event_id {
					return Err(Error::BadRequest(
						ErrorKind::InvalidParam,
						"Server sent event with wrong event id",
					));
				}

				drop(state_lock);
				let pub_key_map = RwLock::new(BTreeMap::new());
				services().rooms.event_handler.fetch_required_signing_keys([&signed_value], &pub_key_map).await?;