membership.rs

        let origin: Box<ServerName> = serde_json::from_value(
            serde_json::to_value(value.get("origin").ok_or(Error::BadRequest(
                ErrorKind::InvalidParam,
                "Event needs an origin field.",
            ))?)
            .expect("CanonicalJson is valid json value"),
        )
        .map_err(|_| Error::BadRequest(ErrorKind::InvalidParam, "Origin field is invalid."))?;

        let pdu_id = server_server::handle_incoming_pdu(
            &origin,
            &event_id,
            room_id,
            value,
            true,
            db,
            &pub_key_map,
        )
        .await
        .map_err(|_| {
            Error::BadRequest(
                ErrorKind::InvalidParam,
                "Error while handling incoming PDU.",
            )
        })?
        .ok_or(Error::BadRequest(
            ErrorKind::InvalidParam,
            "Could not accept incoming PDU as timeline event.",
        ))?;

        let servers = db
            .rooms
            .room_servers(room_id)
            .filter_map(|r| r.ok())
            .filter(|server| &**server != db.globals.server_name());

        db.sending.send_pdu(servers, &pdu_id)?;

        return Ok(());
    }

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

    db.rooms.build_and_append_pdu(
        PduBuilder {
            event_type: EventType::RoomMember,
            content: to_raw_value(&RoomMemberEventContent {
                membership: MembershipState::Invite,
                displayname: db.users.displayname(user_id)?,
                avatar_url: db.users.avatar_url(user_id)?,
                is_direct: Some(is_direct),
                third_party_invite: None,
                blurhash: db.users.blurhash(user_id)?,
                reason: None,
                join_authorized_via_users_server: None,
            })
            .expect("event is valid, we just created it"),
            unsigned: None,
            state_key: Some(user_id.to_string()),
            redacts: None,
        },
        sender_user,
        room_id,
        db,
        &state_lock,
    )?;

    drop(state_lock);

    Ok(())
}