membership.rs

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

use axum_client_ip::InsecureClientIp;
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},
			message::RoomMessageEventContent,
		},
		StateEventType, TimelineEventType,
	},
	serde::Base64,
	state_res, CanonicalJsonObject, CanonicalJsonValue, EventId, OwnedEventId, OwnedRoomId, OwnedServerName,
	OwnedUserId, RoomId, RoomVersionId, ServerName, UserId,
};
use serde_json::value::{to_raw_value, RawValue as RawJsonValue};
use tokio::sync::{MutexGuard, RwLock};
use tracing::{debug, error, info, trace, warn};

use super::get_alias_helper;
use crate::{
	client::{update_avatar_url, update_displayname},
	service::{
		pdu::{gen_event_id_canonical_json, PduBuilder},
		server_is_ours, user_is_local,
	},
	services, utils, Error, PduEvent, Result, Ruma,
};

/// Checks if the room is banned in any way possible and the sender user is not
/// an admin.
///
/// Performs automatic deactivation if `auto_deactivate_banned_room_attempts` is
/// enabled
#[tracing::instrument]
async fn banned_room_check(
	user_id: &UserId, room_id: Option<&RoomId>, server_name: Option<&ServerName>, client_ip: IpAddr,
) -> Result<()> {
	if !services().users.is_admin(user_id)? {
		if let Some(room_id) = room_id {
			if services().rooms.metadata.is_banned(room_id)?
				|| services()
					.globals
					.config
					.forbidden_remote_server_names
					.contains(&room_id.server_name().unwrap().to_owned())
			{
				warn!(
					"User {user_id} who is not an admin attempted to send an invite for or attempted to join a banned \
					 room or banned room server name: {room_id}"
				);

				if services()
					.globals
					.config
					.auto_deactivate_banned_room_attempts
				{
					warn!("Automatically deactivating user {user_id} due to attempted banned room join");
					services()
						.admin
						.send_message(RoomMessageEventContent::text_plain(format!(
							"Automatically deactivating user {user_id} due to attempted banned room join from IP \
							 {client_ip}"
						)))
						.await;

					if let Err(e) = services().users.deactivate_account(user_id) {
						warn!(%user_id, %e, "Failed to deactivate account");
					}

					let all_joined_rooms: Vec<OwnedRoomId> = services()
						.rooms
						.state_cache
						.rooms_joined(user_id)
						.filter_map(Result::ok)
						.collect();

					update_displayname(user_id.into(), None, all_joined_rooms.clone()).await?;
					update_avatar_url(user_id.into(), None, None, all_joined_rooms).await?;
					leave_all_rooms(user_id).await;
				}

				return Err(Error::BadRequest(
					ErrorKind::forbidden(),
					"This room is banned on this homeserver.",
				));
			}
		} else if let Some(server_name) = server_name {
			if services()
				.globals
				.config
				.forbidden_remote_server_names
				.contains(&server_name.to_owned())
			{
				warn!(
					"User {user_id} who is not an admin tried joining a room which has the server name {server_name} \
					 that is globally forbidden. Rejecting.",
				);

				if services()
					.globals
					.config
					.auto_deactivate_banned_room_attempts
				{
					warn!("Automatically deactivating user {user_id} due to attempted banned room join");
					services()
						.admin
						.send_message(RoomMessageEventContent::text_plain(format!(
							"Automatically deactivating user {user_id} due to attempted banned room join from IP \
							 {client_ip}"
						)))
						.await;

					if let Err(e) = services().users.deactivate_account(user_id) {
						warn!(%user_id, %e, "Failed to deactivate account");
					}

					let all_joined_rooms: Vec<OwnedRoomId> = services()
						.rooms
						.state_cache
						.rooms_joined(user_id)
						.filter_map(Result::ok)
						.collect();

					update_displayname(user_id.into(), None, all_joined_rooms.clone()).await?;
					update_avatar_url(user_id.into(), None, None, all_joined_rooms).await?;
					leave_all_rooms(user_id).await;
				}

				return Err(Error::BadRequest(
					ErrorKind::forbidden(),
					"This remote server is banned on this homeserver.",
				));
			}
		}
	}

	Ok(())
}

/// # `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
#[tracing::instrument(skip_all, fields(%client_ip))]
pub(crate) async fn join_room_by_id_route(
	InsecureClientIp(client_ip): InsecureClientIp, 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");

	banned_room_check(sender_user, Some(&body.room_id), body.room_id.server_name(), client_ip).await?;

	// There is no body.server_name for /roomId/join
	let mut servers = services()
		.rooms
		.state_cache
		.servers_invite_via(&body.room_id)
		.filter_map(Result::ok)
		.collect::<Vec<_>>();

	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()),
	);

	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: use the server name query
///   param if specified. if not specified, asks other servers over federation
///   via room alias server name and room ID server name
#[tracing::instrument(skip_all, fields(%client_ip))]
pub(crate) async fn join_room_by_id_or_alias_route(
	InsecureClientIp(client_ip): InsecureClientIp, 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) => {
			banned_room_check(sender_user, Some(&room_id), room_id.server_name(), client_ip).await?;

			let mut servers = body.server_name.clone();
			servers.extend(
				services()
					.rooms
					.state_cache
					.servers_invite_via(&room_id)
					.filter_map(Result::ok),
			);

			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()),
			);

			if let Some(server) = room_id.server_name() {
				servers.push(server.to_owned());
			}

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

			banned_room_check(sender_user, Some(&response.room_id), Some(room_alias.server_name()), client_ip).await?;

			let mut servers = body.server_name;
			servers.extend(response.servers);
			servers.extend(
				services()
					.rooms
					.state_cache
					.servers_invite_via(&response.room_id)
					.filter_map(Result::ok),
			);

			servers.extend(
				services()
					.rooms
					.state_cache
					.invite_state(sender_user, &response.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()),
			);

			(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(crate) 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.
#[tracing::instrument(skip_all, fields(%client_ip))]
pub(crate) async fn invite_user_route(
	InsecureClientIp(client_ip): InsecureClientIp, 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.",
		));
	}

	banned_room_check(sender_user, Some(&body.room_id), body.room_id.server_name(), client_ip).await?;

	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(crate) 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(crate) 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: None,
				avatar_url: None,
				is_direct: None,
				third_party_invite: None,
				blurhash: services().users.blurhash(&body.user_id).unwrap_or_default(),
				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: None,
						avatar_url: None,
						blurhash: services().users.blurhash(&body.user_id).unwrap_or_default(),
						reason: body.reason.clone(),
						join_authorized_via_users_server: None,
						..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(crate) 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);
	event.join_authorized_via_users_server = None;

	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(crate) 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");

	if services()
		.rooms
		.state_cache
		.is_joined(sender_user, &body.room_id)?
	{
		return Err(Error::BadRequest(
			ErrorKind::Unknown,
			"You must leave the room before forgetting it",
		));
	}

	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(crate) 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(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(crate) 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(crate) 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(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 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");

	if matches!(services().rooms.state_cache.is_joined(sender_user, room_id), Ok(true)) {
		info!("{sender_user} is already joined in {room_id}");
		return Ok(join_room_by_id::v3::Response {
			room_id: room_id.into(),
		});
	}

	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)?
	{
		join_room_by_id_helper_remote(sender_user, room_id, reason, servers, third_party_signed, state_lock).await
	} else {
		join_room_by_id_helper_local(sender_user, room_id, reason, servers, third_party_signed, state_lock).await
	}
}

async fn join_room_by_id_helper_remote(
	sender_user: &UserId, room_id: &RoomId, reason: Option<String>, servers: &[OwnedServerName],
	_third_party_signed: Option<&ThirdPartySigned>, state_lock: MutexGuard<'_, ()>,
) -> Result<join_room_by_id::v3::Response> {
	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 keep the "event_id" in the pdu only in v1 or
	// v2 rooms
	match room_version_id {
		RoomVersionId::V1 | RoomVersionId::V2 => {},
		_ => {
			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 Ok((signed_event_id, signed_value)) = gen_event_id_canonical_json(signed_raw, &room_version_id)
					else {
						// 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 Ok((event_id, value)) = result.await else {
			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 Ok((event_id, value)) = result.await else {
			continue;
		};

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

	debug!("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::forbidden(), "Auth check failed")
	})?;

	if !auth_check {
		return Err(Error::BadRequest(ErrorKind::forbidden(), "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");