lemmy/crates/apub/src/lib.rs

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use crate::fetcher::post_or_comment::PostOrComment;
use activitypub_federation::{
core::signatures::PublicKey,
traits::{Actor, ApubObject},
InstanceSettings,
LocalInstance,
UrlVerifier,
};
use async_trait::async_trait;
use lemmy_api_common::context::LemmyContext;
use lemmy_db_schema::{
source::{activity::Activity, instance::Instance, local_site::LocalSite},
utils::DbPool,
};
use lemmy_utils::{error::LemmyError, settings::structs::Settings};
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use once_cell::sync::Lazy;
use tokio::sync::OnceCell;
use url::Url;
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pub mod activities;
pub(crate) 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;
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const FEDERATION_HTTP_FETCH_LIMIT: i32 = 25;
static CONTEXT: Lazy<Vec<serde_json::Value>> = Lazy::new(|| {
serde_json::from_str(include_str!("../assets/lemmy/context.json")).expect("parse context")
});
// TODO: store this in context? but its only used in this crate, no need to expose it elsewhere
// TODO this singleton needs to be redone to account for live data.
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async fn local_instance(context: &LemmyContext) -> &'static LocalInstance {
static LOCAL_INSTANCE: OnceCell<LocalInstance> = OnceCell::const_new();
LOCAL_INSTANCE
.get_or_init(|| async {
// Local site may be missing
let local_site = &LocalSite::read(context.pool()).await;
let worker_count = local_site
.as_ref()
.map(|l| l.federation_worker_count)
.unwrap_or(64) as u64;
let settings = InstanceSettings::builder()
.http_fetch_retry_limit(FEDERATION_HTTP_FETCH_LIMIT)
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.worker_count(worker_count)
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.debug(cfg!(debug_assertions))
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.http_signature_compat(true)
.url_verifier(Box::new(VerifyUrlData(context.clone())))
.build()
.expect("configure federation");
LocalInstance::new(
context.settings().hostname.clone(),
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context.client().clone(),
settings,
)
})
.await
}
#[derive(Clone)]
struct VerifyUrlData(LemmyContext);
#[async_trait]
impl UrlVerifier for VerifyUrlData {
async fn verify(&self, url: &Url) -> Result<(), &'static str> {
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let local_site_data = fetch_local_site_data(self.0.pool())
.await
.expect("read local site data");
check_apub_id_valid(url, &local_site_data, self.0.settings())
}
}
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/// 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)
///
/// `use_strict_allowlist` should be true only when parsing a remote community, or when parsing a
/// post/comment in a local community.
#[tracing::instrument(skip(settings, local_site_data))]
fn check_apub_id_valid(
apub_id: &Url,
local_site_data: &LocalSiteData,
settings: &Settings,
) -> Result<(), &'static str> {
let domain = apub_id.domain().expect("apud id has domain").to_string();
let local_instance = settings
.get_hostname_without_port()
.expect("local hostname is valid");
if domain == local_instance {
return Ok(());
}
if !local_site_data
.local_site
.as_ref()
.map(|l| l.federation_enabled)
.unwrap_or(true)
{
return Err("Federation disabled");
}
if apub_id.scheme() != settings.get_protocol_string() {
return Err("Invalid protocol scheme");
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}
if let Some(blocked) = local_site_data.blocked_instances.as_ref() {
if blocked.iter().any(|i| domain.eq(&i.domain)) {
return Err("Domain is blocked");
}
}
if let Some(allowed) = local_site_data.allowed_instances.as_ref() {
if !allowed.iter().any(|i| domain.eq(&i.domain)) {
return Err("Domain is not in allowlist");
}
}
Ok(())
}
#[derive(Clone)]
pub(crate) struct LocalSiteData {
local_site: Option<LocalSite>,
allowed_instances: Option<Vec<Instance>>,
blocked_instances: Option<Vec<Instance>>,
}
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pub(crate) async fn fetch_local_site_data(
pool: &DbPool,
) -> Result<LocalSiteData, diesel::result::Error> {
// LocalSite may be missing
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let local_site = LocalSite::read(pool).await.ok();
let allowed = Instance::allowlist(pool).await?;
let blocked = Instance::blocklist(pool).await?;
// These can return empty vectors, so convert them to options
let allowed_instances = (!allowed.is_empty()).then_some(allowed);
let blocked_instances = (!blocked.is_empty()).then_some(blocked);
Ok(LocalSiteData {
local_site,
allowed_instances,
blocked_instances,
})
}
#[tracing::instrument(skip(settings, local_site_data))]
pub(crate) fn check_apub_id_valid_with_strictness(
apub_id: &Url,
is_strict: bool,
local_site_data: &LocalSiteData,
settings: &Settings,
) -> Result<(), LemmyError> {
check_apub_id_valid(apub_id, local_site_data, settings).map_err(LemmyError::from_message)?;
let domain = apub_id.domain().expect("apud id has domain").to_string();
let local_instance = settings
.get_hostname_without_port()
.expect("local hostname is valid");
if domain == local_instance {
return Ok(());
}
if let Some(allowed) = local_site_data.allowed_instances.as_ref() {
// Only check allowlist if this is a community
if is_strict {
// need to allow this explicitly because apub receive might contain objects from our local
// instance.
let mut allowed_and_local = allowed
.iter()
.map(|i| i.domain.clone())
.collect::<Vec<String>>();
allowed_and_local.push(local_instance);
if !allowed_and_local.contains(&domain) {
return Err(LemmyError::from_message(
"Federation forbidden by strict allowlist",
));
}
}
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}
Ok(())
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}
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/// Store a sent or received activity in the database, for logging purposes. These records are not
/// persistent.
#[tracing::instrument(skip(pool))]
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async fn insert_activity(
ap_id: &Url,
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activity: serde_json::Value,
local: bool,
sensitive: bool,
pool: &DbPool,
) -> Result<bool, LemmyError> {
let ap_id = ap_id.clone().into();
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Ok(Activity::insert(pool, ap_id, activity, local, Some(sensitive)).await?)
}
/// Common methods provided by ActivityPub actors (community and person). Not all methods are
/// implemented by all actors.
pub trait ActorType: Actor + ApubObject {
fn actor_id(&self) -> Url;
fn private_key(&self) -> Option<String>;
fn get_public_key(&self) -> PublicKey {
PublicKey::new_main_key(self.actor_id(), self.public_key().to_string())
}
}
#[async_trait::async_trait(?Send)]
pub trait SendActivity {
type Response;
async fn send_activity(
_request: &Self,
_response: &Self::Response,
_context: &LemmyContext,
) -> Result<(), LemmyError> {
Ok(())
}
}