use crate::fetcher::post_or_comment::PostOrComment; use activitypub_federation::{ config::{Data, UrlVerifier}, error::Error as ActivityPubError, }; use async_trait::async_trait; use lemmy_api_common::context::LemmyContext; use lemmy_db_schema::{ source::{activity::ReceivedActivity, instance::Instance, local_site::LocalSite}, utils::{ActualDbPool, DbPool}, }; use lemmy_utils::{ error::{LemmyError, LemmyErrorType, LemmyResult}, CACHE_DURATION_FEDERATION, }; use moka::future::Cache; use once_cell::sync::Lazy; use serde_json::Value; use std::sync::Arc; use url::Url; pub mod activities; pub mod activity_lists; pub mod api; pub(crate) mod collections; pub mod fetcher; pub mod http; pub(crate) mod mentions; pub mod objects; pub mod protocol; pub const FEDERATION_HTTP_FETCH_LIMIT: u32 = 50; /// Only include a basic context to save space and bandwidth. The main context is hosted statically /// on join-lemmy.org. Include activitystreams explicitly for better compat, but this could /// theoretically also be moved. pub static FEDERATION_CONTEXT: Lazy = Lazy::new(|| { Value::Array(vec![ Value::String("https://join-lemmy.org/context.json".to_string()), Value::String("https://www.w3.org/ns/activitystreams".to_string()), ]) }); #[derive(Clone)] pub struct VerifyUrlData(pub ActualDbPool); #[async_trait] impl UrlVerifier for VerifyUrlData { async fn verify(&self, url: &Url) -> Result<(), ActivityPubError> { let local_site_data = local_site_data_cached(&mut (&self.0).into()) .await .expect("read local site data"); check_apub_id_valid(url, &local_site_data).map_err(|err| match err { LemmyError { error_type: LemmyErrorType::FederationDisabled, .. } => ActivityPubError::Other("Federation disabled".into()), LemmyError { error_type: LemmyErrorType::DomainBlocked(domain), .. } => ActivityPubError::Other(format!("Domain {domain:?} is blocked")), LemmyError { error_type: LemmyErrorType::DomainNotInAllowList(domain), .. } => ActivityPubError::Other(format!("Domain {domain:?} is not in allowlist")), _ => ActivityPubError::Other("Failed validating apub id".into()), })?; Ok(()) } } /// Checks if the ID is allowed for sending or receiving. /// /// In particular, it checks for: /// - federation being enabled (if its disabled, only local URLs are allowed) /// - the correct scheme (either http or https) /// - URL being in the allowlist (if it is active) /// - URL not being in the blocklist (if it is active) #[tracing::instrument(skip(local_site_data))] fn check_apub_id_valid(apub_id: &Url, local_site_data: &LocalSiteData) -> Result<(), LemmyError> { let domain = apub_id.domain().expect("apud id has domain").to_string(); if !local_site_data .local_site .as_ref() .map(|l| l.federation_enabled) .unwrap_or(true) { Err(LemmyErrorType::FederationDisabled)? } if local_site_data .blocked_instances .iter() .any(|i| domain.to_lowercase().eq(&i.domain.to_lowercase())) { Err(LemmyErrorType::DomainBlocked(domain.clone()))? } // Only check this if there are instances in the allowlist if !local_site_data.allowed_instances.is_empty() && !local_site_data .allowed_instances .iter() .any(|i| domain.to_lowercase().eq(&i.domain.to_lowercase())) { Err(LemmyErrorType::DomainNotInAllowList(domain))? } Ok(()) } #[derive(Clone)] pub(crate) struct LocalSiteData { local_site: Option, allowed_instances: Vec, blocked_instances: Vec, } pub(crate) async fn local_site_data_cached( pool: &mut DbPool<'_>, ) -> LemmyResult> { // All incoming and outgoing federation actions read the blocklist/allowlist and slur filters // multiple times. This causes a huge number of database reads if we hit the db directly. So we // cache these values for a short time, which will already make a huge difference and ensures that // changes take effect quickly. static CACHE: Lazy>> = Lazy::new(|| { Cache::builder() .max_capacity(1) .time_to_live(CACHE_DURATION_FEDERATION) .build() }); Ok( CACHE .try_get_with((), async { let (local_site, allowed_instances, blocked_instances) = lemmy_db_schema::try_join_with_pool!(pool => ( // LocalSite may be missing |pool| async { Ok(LocalSite::read(pool).await.ok()) }, Instance::allowlist, Instance::blocklist ))?; Ok::<_, diesel::result::Error>(Arc::new(LocalSiteData { local_site, allowed_instances, blocked_instances, })) }) .await?, ) } pub(crate) async fn check_apub_id_valid_with_strictness( apub_id: &Url, is_strict: bool, context: &LemmyContext, ) -> Result<(), LemmyError> { let domain = apub_id.domain().expect("apud id has domain").to_string(); let local_instance = context .settings() .get_hostname_without_port() .expect("local hostname is valid"); if domain == local_instance { return Ok(()); } let local_site_data = local_site_data_cached(&mut context.pool()).await?; check_apub_id_valid(apub_id, &local_site_data)?; // Only check allowlist if this is a community, and there are instances in the allowlist if is_strict && !local_site_data.allowed_instances.is_empty() { // need to allow this explicitly because apub receive might contain objects from our local // instance. let mut allowed_and_local = local_site_data .allowed_instances .iter() .map(|i| i.domain.clone()) .collect::>(); let local_instance = context .settings() .get_hostname_without_port() .expect("local hostname is valid"); allowed_and_local.push(local_instance); let domain = apub_id.domain().expect("apud id has domain").to_string(); if !allowed_and_local.contains(&domain) { Err(LemmyErrorType::FederationDisabledByStrictAllowList)? } } Ok(()) } /// Store received activities in the database. /// /// This ensures that the same activity doesnt get received and processed more than once, which /// would be a waste of resources. #[tracing::instrument(skip(data))] async fn insert_received_activity( ap_id: &Url, data: &Data, ) -> Result<(), LemmyError> { ReceivedActivity::create(&mut data.pool(), &ap_id.clone().into()).await?; Ok(()) }