lemmy/server/src/apub/inbox/shared_inbox.rs

use crate::{
  apub::{
    check_is_apub_id_valid,
    community::do_announce,
    extensions::signatures::verify,
    fetcher::{
      get_or_fetch_and_upsert_actor,
      get_or_fetch_and_upsert_community,
      get_or_fetch_and_upsert_user,
    },
    inbox::activities::{
      announce::receive_announce,
      create::receive_create,
      delete::receive_delete,
      dislike::receive_dislike,
      like::receive_like,
      remove::receive_remove,
      undo::receive_undo,
      update::receive_update,
    },
    insert_activity,
  },
  LemmyContext,
};
use activitystreams::{
  activity::{ActorAndObject, ActorAndObjectRef},
  base::{AsBase, Extends},
  object::AsObject,
  prelude::*,
};
use actix_web::{web, HttpRequest, HttpResponse};
use anyhow::Context;
use lemmy_db::user::User_;
use lemmy_utils::{location_info, LemmyError};
use log::debug;
use serde::{Deserialize, Serialize};
use std::fmt::Debug;
use url::Url;

#[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd, Deserialize, Serialize)]
#[serde(rename_all = "PascalCase")]
pub enum ValidTypes {
  Create,
  Update,
  Like,
  Dislike,
  Delete,
  Undo,
  Remove,
  Announce,
}

// TODO: this isnt entirely correct, cause some of these activities are not ActorAndObject,
//       but it might still work due to the anybase conversion
pub type AcceptedActivities = ActorAndObject<ValidTypes>;

/// Handler for all incoming activities to user inboxes.
pub async fn shared_inbox(
  request: HttpRequest,
  input: web::Json<AcceptedActivities>,
  context: web::Data<LemmyContext>,
) -> Result<HttpResponse, LemmyError> {
  let activity = input.into_inner();

  let json = serde_json::to_string(&activity)?;
  debug!("Shared inbox received activity: {}", json);

  // TODO: if we already received an activity with identical ID, then ignore this (same in other inboxes)

  let sender = &activity
    .actor()?
    .to_owned()
    .single_xsd_any_uri()
    .context(location_info!())?;
  let community = get_community_id_from_activity(&activity)?;

  check_is_apub_id_valid(sender)?;
  check_is_apub_id_valid(&community)?;

  let actor = get_or_fetch_and_upsert_actor(sender, &context).await?;
  verify(&request, actor.as_ref())?;

  let any_base = activity.clone().into_any_base()?;
  let kind = activity.kind().context(location_info!())?;
  let res = match kind {
    ValidTypes::Announce => receive_announce(any_base, &context).await,
    ValidTypes::Create => receive_create(any_base, &context).await,
    ValidTypes::Update => receive_update(any_base, &context).await,
    ValidTypes::Like => receive_like(any_base, &context).await,
    ValidTypes::Dislike => receive_dislike(any_base, &context).await,
    ValidTypes::Remove => receive_remove(any_base, &context).await,
    ValidTypes::Delete => receive_delete(any_base, &context).await,
    ValidTypes::Undo => receive_undo(any_base, &context).await,
  };

  insert_activity(actor.user_id(), activity.clone(), false, context.pool()).await?;
  res
}

pub(in crate::apub::inbox) fn receive_unhandled_activity<A>(
  activity: A,
) -> Result<HttpResponse, LemmyError>
where
  A: Debug,
{
  debug!("received unhandled activity type: {:?}", activity);
  Ok(HttpResponse::NotImplemented().finish())
}

pub(in crate::apub::inbox) async fn get_user_from_activity<T, A>(
  activity: &T,
  context: &LemmyContext,
) -> Result<User_, LemmyError>
where
  T: AsBase<A> + ActorAndObjectRef,
{
  let actor = activity.actor()?;
  let user_uri = actor.as_single_xsd_any_uri().context(location_info!())?;
  get_or_fetch_and_upsert_user(&user_uri, context).await
}

pub(in crate::apub::inbox) fn get_community_id_from_activity<T, A>(
  activity: &T,
) -> Result<Url, LemmyError>
where
  T: AsBase<A> + ActorAndObjectRef + AsObject<A>,
{
  let cc = activity.cc().context(location_info!())?;
  let cc = cc.as_many().context(location_info!())?;
  Ok(
    cc.first()
      .context(location_info!())?
      .as_xsd_any_uri()
      .context(location_info!())?
      .to_owned(),
  )
}

pub(in crate::apub::inbox) async fn announce_if_community_is_local<T, Kind>(
  activity: T,
  user: &User_,
  context: &LemmyContext,
) -> Result<(), LemmyError>
where
  T: AsObject<Kind>,
  T: Extends<Kind>,
  Kind: Serialize,
  <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
{
  let cc = activity.cc().context(location_info!())?;
  let cc = cc.as_many().context(location_info!())?;
  let community_followers_uri = cc
    .first()
    .context(location_info!())?
    .as_xsd_any_uri()
    .context(location_info!())?;
  // TODO: this is hacky but seems to be the only way to get the community ID
  let community_uri = community_followers_uri
    .to_string()
    .replace("/followers", "");
  let community = get_or_fetch_and_upsert_community(&Url::parse(&community_uri)?, context).await?;

  if community.local {
    do_announce(activity.into_any_base()?, &community, &user, context).await?;
  }
  Ok(())
}