10 files changed, 514 insertions, 0 deletions

diff --git a/fedi/live_federation/activities/create_post.rs b/fedi/live_federation/activities/create_post.rs
new file mode 100644
index 0000000..66928a6
--- /dev/null
+++ b/fedi/live_federation/activities/create_post.rs
@@ -0,0 +1,69 @@
+use crate::{
+    database::DatabaseHandle,
+    error::Error,
+    objects::{person::DbUser, post::Note},
+    utils::generate_object_id,
+    DbPost,
+};
+use activitypub_federation::{
+    activity_queue::send_activity,
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::activity::CreateType,
+    protocol::{context::WithContext, helpers::deserialize_one_or_many},
+    traits::{ActivityHandler, Object},
+};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+#[derive(Deserialize, Serialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct CreatePost {
+    pub(crate) actor: ObjectId<DbUser>,
+    #[serde(deserialize_with = "deserialize_one_or_many")]
+    pub(crate) to: Vec<Url>,
+    pub(crate) object: Note,
+    #[serde(rename = "type")]
+    pub(crate) kind: CreateType,
+    pub(crate) id: Url,
+}
+
+impl CreatePost {
+    pub async fn send(note: Note, inbox: Url, data: &Data<DatabaseHandle>) -> Result<(), Error> {
+        print!("Sending reply to {}", &note.attributed_to);
+        let create = CreatePost {
+            actor: note.attributed_to.clone(),
+            to: note.to.clone(),
+            object: note,
+            kind: CreateType::Create,
+            id: generate_object_id(data.domain())?,
+        };
+        let create_with_context = WithContext::new_default(create);
+        send_activity(create_with_context, &data.local_user(), vec![inbox], data).await?;
+        Ok(())
+    }
+}
+
+#[async_trait::async_trait]
+impl ActivityHandler for CreatePost {
+    type DataType = DatabaseHandle;
+    type Error = crate::error::Error;
+
+    fn id(&self) -> &Url {
+        &self.id
+    }
+
+    fn actor(&self) -> &Url {
+        self.actor.inner()
+    }
+
+    async fn verify(&self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        DbPost::verify(&self.object, &self.id, data).await?;
+        Ok(())
+    }
+
+    async fn receive(self, data: &Data<Self::DataType>) -> Result<(), Self::Error> {
+        DbPost::from_json(self.object, data).await?;
+        Ok(())
+    }
+}
diff --git a/fedi/live_federation/activities/mod.rs b/fedi/live_federation/activities/mod.rs
new file mode 100644
index 0000000..7e15ee0
--- /dev/null
+++ b/fedi/live_federation/activities/mod.rs
@@ -0,0 +1 @@
+pub mod create_post;
diff --git a/fedi/live_federation/database.rs b/fedi/live_federation/database.rs
new file mode 100644
index 0000000..967c534
--- /dev/null
+++ b/fedi/live_federation/database.rs
@@ -0,0 +1,26 @@
+use crate::{objects::person::DbUser, Error};
+use anyhow::anyhow;
+use std::sync::{Arc, Mutex};
+
+pub type DatabaseHandle = Arc<Database>;
+
+/// Our "database" which contains all known users (local and federated)
+pub struct Database {
+    pub users: Mutex<Vec<DbUser>>,
+}
+
+impl Database {
+    pub fn local_user(&self) -> DbUser {
+        let lock = self.users.lock().unwrap();
+        lock.first().unwrap().clone()
+    }
+
+    pub fn read_user(&self, name: &str) -> Result<DbUser, Error> {
+        let db_user = self.local_user();
+        if name == db_user.name {
+            Ok(db_user)
+        } else {
+            Err(anyhow!("Invalid user {name}").into())
+        }
+    }
+}
diff --git a/fedi/live_federation/error.rs b/fedi/live_federation/error.rs
new file mode 100644
index 0000000..3ef1819
--- /dev/null
+++ b/fedi/live_federation/error.rs
@@ -0,0 +1,20 @@
+use std::fmt::{Display, Formatter};
+
+/// Necessary because of this issue: https://github.com/actix/actix-web/issues/1711
+#[derive(Debug)]
+pub struct Error(pub(crate) anyhow::Error);
+
+impl Display for Error {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(&self.0, f)
+    }
+}
+
+impl<T> From<T> for Error
+where
+    T: Into<anyhow::Error>,
+{
+    fn from(t: T) -> Self {
+        Error(t.into())
+    }
+}
diff --git a/fedi/live_federation/http.rs b/fedi/live_federation/http.rs
new file mode 100644
index 0000000..d626396
--- /dev/null
+++ b/fedi/live_federation/http.rs
@@ -0,0 +1,69 @@
+use crate::{
+    database::DatabaseHandle,
+    error::Error,
+    objects::person::{DbUser, Person, PersonAcceptedActivities},
+};
+use activitypub_federation::{
+    axum::{
+        inbox::{receive_activity, ActivityData},
+        json::FederationJson,
+    },
+    config::Data,
+    fetch::webfinger::{build_webfinger_response, extract_webfinger_name, Webfinger},
+    protocol::context::WithContext,
+    traits::Object,
+};
+use axum::{
+    extract::{Path, Query},
+    response::{IntoResponse, Response},
+    Json,
+};
+use axum_macros::debug_handler;
+use http::StatusCode;
+use serde::Deserialize;
+
+impl IntoResponse for Error {
+    fn into_response(self) -> Response {
+        (StatusCode::INTERNAL_SERVER_ERROR, format!("{}", self.0)).into_response()
+    }
+}
+
+#[debug_handler]
+pub async fn http_get_user(
+    Path(name): Path<String>,
+    data: Data<DatabaseHandle>,
+) -> Result<FederationJson<WithContext<Person>>, Error> {
+    let db_user = data.read_user(&name)?;
+    let json_user = db_user.into_json(&data).await?;
+    Ok(FederationJson(WithContext::new_default(json_user)))
+}
+
+#[debug_handler]
+pub async fn http_post_user_inbox(
+    data: Data<DatabaseHandle>,
+    activity_data: ActivityData,
+) -> impl IntoResponse {
+    receive_activity::<WithContext<PersonAcceptedActivities>, DbUser, DatabaseHandle>(
+        activity_data,
+        &data,
+    )
+    .await
+}
+
+#[derive(Deserialize)]
+pub struct WebfingerQuery {
+    resource: String,
+}
+
+#[debug_handler]
+pub async fn webfinger(
+    Query(query): Query<WebfingerQuery>,
+    data: Data<DatabaseHandle>,
+) -> Result<Json<Webfinger>, Error> {
+    let name = extract_webfinger_name(&query.resource, &data)?;
+    let db_user = data.read_user(&name)?;
+    Ok(Json(build_webfinger_response(
+        query.resource,
+        db_user.ap_id.into_inner(),
+    )))
+}
diff --git a/fedi/live_federation/main.rs b/fedi/live_federation/main.rs
new file mode 100644
index 0000000..4326226
--- /dev/null
+++ b/fedi/live_federation/main.rs
@@ -0,0 +1,70 @@
+use crate::{
+    database::Database,
+    http::{http_get_user, http_post_user_inbox, webfinger},
+    objects::{person::DbUser, post::DbPost},
+    utils::generate_object_id,
+};
+use activitypub_federation::config::{FederationConfig, FederationMiddleware};
+use axum::{
+    routing::{get, post},
+    Router,
+};
+use error::Error;
+use std::{
+    net::ToSocketAddrs,
+    sync::{Arc, Mutex},
+};
+use tracing::log::{info, LevelFilter};
+
+mod activities;
+mod database;
+mod error;
+#[allow(clippy::diverging_sub_expression, clippy::items_after_statements)]
+mod http;
+mod objects;
+mod utils;
+
+const DOMAIN: &str = "example.com";
+const LOCAL_USER_NAME: &str = "alison";
+const BIND_ADDRESS: &str = "localhost:8003";
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    env_logger::builder()
+        .filter_level(LevelFilter::Warn)
+        .filter_module("activitypub_federation", LevelFilter::Info)
+        .filter_module("live_federation", LevelFilter::Info)
+        .format_timestamp(None)
+        .init();
+
+    info!("Setup local user and database");
+    let local_user = DbUser::new(DOMAIN, LOCAL_USER_NAME)?;
+    let database = Arc::new(Database {
+        users: Mutex::new(vec![local_user]),
+    });
+
+    info!("Setup configuration");
+    let config = FederationConfig::builder()
+        .domain(DOMAIN)
+        .app_data(database)
+        .build()
+        .await?;
+
+    info!("Listen with HTTP server on {BIND_ADDRESS}");
+    let config = config.clone();
+    let app = Router::new()
+        .route("/:user", get(http_get_user))
+        .route("/:user/inbox", post(http_post_user_inbox))
+        .route("/.well-known/webfinger", get(webfinger))
+        .layer(FederationMiddleware::new(config));
+
+    let addr = BIND_ADDRESS
+        .to_socket_addrs()?
+        .next()
+        .expect("Failed to lookup domain name");
+    axum::Server::bind(&addr)
+        .serve(app.into_make_service())
+        .await?;
+
+    Ok(())
+}
diff --git a/fedi/live_federation/objects/mod.rs b/fedi/live_federation/objects/mod.rs
new file mode 100644
index 0000000..b5239ab
--- /dev/null
+++ b/fedi/live_federation/objects/mod.rs
@@ -0,0 +1,2 @@
+pub mod person;
+pub mod post;
diff --git a/fedi/live_federation/objects/person.rs b/fedi/live_federation/objects/person.rs
new file mode 100644
index 0000000..d9439ea
--- /dev/null
+++ b/fedi/live_federation/objects/person.rs
@@ -0,0 +1,140 @@
+use crate::{activities::create_post::CreatePost, database::DatabaseHandle, error::Error};
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    http_signatures::generate_actor_keypair,
+    kinds::actor::PersonType,
+    protocol::{public_key::PublicKey, verification::verify_domains_match},
+    traits::{ActivityHandler, Actor, Object},
+};
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use std::fmt::Debug;
+use url::Url;
+
+#[derive(Debug, Clone)]
+pub struct DbUser {
+    pub name: String,
+    pub ap_id: ObjectId<DbUser>,
+    pub inbox: Url,
+    // exists for all users (necessary to verify http signatures)
+    pub public_key: String,
+    // exists only for local users
+    pub private_key: Option<String>,
+    last_refreshed_at: DateTime<Utc>,
+    pub followers: Vec<Url>,
+    pub local: bool,
+}
+
+/// List of all activities which this actor can receive.
+#[derive(Deserialize, Serialize, Debug)]
+#[serde(untagged)]
+#[enum_delegate::implement(ActivityHandler)]
+pub enum PersonAcceptedActivities {
+    CreateNote(CreatePost),
+}
+
+impl DbUser {
+    pub fn new(hostname: &str, name: &str) -> Result<DbUser, Error> {
+        let ap_id = Url::parse(&format!("https://{}/{}", hostname, &name))?.into();
+        let inbox = Url::parse(&format!("https://{}/{}/inbox", hostname, &name))?;
+        let keypair = generate_actor_keypair()?;
+        Ok(DbUser {
+            name: name.to_string(),
+            ap_id,
+            inbox,
+            public_key: keypair.public_key,
+            private_key: Some(keypair.private_key),
+            last_refreshed_at: Utc::now(),
+            followers: vec![],
+            local: true,
+        })
+    }
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Person {
+    #[serde(rename = "type")]
+    kind: PersonType,
+    preferred_username: String,
+    id: ObjectId<DbUser>,
+    inbox: Url,
+    public_key: PublicKey,
+}
+
+#[async_trait::async_trait]
+impl Object for DbUser {
+    type DataType = DatabaseHandle;
+    type Kind = Person;
+    type Error = Error;
+
+    fn last_refreshed_at(&self) -> Option<DateTime<Utc>> {
+        Some(self.last_refreshed_at)
+    }
+
+    async fn read_from_id(
+        object_id: Url,
+        data: &Data<Self::DataType>,
+    ) -> Result<Option<Self>, Self::Error> {
+        let users = data.users.lock().unwrap();
+        let res = users
+            .clone()
+            .into_iter()
+            .find(|u| u.ap_id.inner() == &object_id);
+        Ok(res)
+    }
+
+    async fn into_json(self, _data: &Data<Self::DataType>) -> Result<Self::Kind, Self::Error> {
+        Ok(Person {
+            preferred_username: self.name.clone(),
+            kind: Default::default(),
+            id: self.ap_id.clone(),
+            inbox: self.inbox.clone(),
+            public_key: self.public_key(),
+        })
+    }
+
+    async fn verify(
+        json: &Self::Kind,
+        expected_domain: &Url,
+        _data: &Data<Self::DataType>,
+    ) -> Result<(), Self::Error> {
+        verify_domains_match(json.id.inner(), expected_domain)?;
+        Ok(())
+    }
+
+    async fn from_json(
+        json: Self::Kind,
+        _data: &Data<Self::DataType>,
+    ) -> Result<Self, Self::Error> {
+        Ok(DbUser {
+            name: json.preferred_username,
+            ap_id: json.id,
+            inbox: json.inbox,
+            public_key: json.public_key.public_key_pem,
+            private_key: None,
+            last_refreshed_at: Utc::now(),
+            followers: vec![],
+            local: false,
+        })
+    }
+}
+
+impl Actor for DbUser {
+    fn id(&self) -> Url {
+        self.ap_id.inner().clone()
+    }
+
+    fn public_key_pem(&self) -> &str {
+        &self.public_key
+    }
+
+    fn private_key_pem(&self) -> Option<String> {
+        self.private_key.clone()
+    }
+
+    fn inbox(&self) -> Url {
+        self.inbox.clone()
+    }
+}
diff --git a/fedi/live_federation/objects/post.rs b/fedi/live_federation/objects/post.rs
new file mode 100644
index 0000000..9a08b9d
--- /dev/null
+++ b/fedi/live_federation/objects/post.rs
@@ -0,0 +1,104 @@
+use crate::{
+    activities::create_post::CreatePost,
+    database::DatabaseHandle,
+    error::Error,
+    generate_object_id,
+    objects::person::DbUser,
+};
+use activitypub_federation::{
+    config::Data,
+    fetch::object_id::ObjectId,
+    kinds::{object::NoteType, public},
+    protocol::{helpers::deserialize_one_or_many, verification::verify_domains_match},
+    traits::{Actor, Object},
+};
+use activitystreams_kinds::link::MentionType;
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+#[derive(Clone, Debug)]
+pub struct DbPost {
+    pub text: String,
+    pub ap_id: ObjectId<DbPost>,
+    pub creator: ObjectId<DbUser>,
+    pub local: bool,
+}
+
+#[derive(Deserialize, Serialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct Note {
+    #[serde(rename = "type")]
+    kind: NoteType,
+    id: ObjectId<DbPost>,
+    pub(crate) attributed_to: ObjectId<DbUser>,
+    #[serde(deserialize_with = "deserialize_one_or_many")]
+    pub(crate) to: Vec<Url>,
+    content: String,
+    in_reply_to: Option<ObjectId<DbPost>>,
+    tag: Vec<Mention>,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct Mention {
+    pub href: Url,
+    #[serde(rename = "type")]
+    pub kind: MentionType,
+}
+
+#[async_trait::async_trait]
+impl Object for DbPost {
+    type DataType = DatabaseHandle;
+    type Kind = Note;
+    type Error = Error;
+
+    async fn read_from_id(
+        _object_id: Url,
+        _data: &Data<Self::DataType>,
+    ) -> Result<Option<Self>, Self::Error> {
+        Ok(None)
+    }
+
+    async fn into_json(self, _data: &Data<Self::DataType>) -> Result<Self::Kind, Self::Error> {
+        unimplemented!()
+    }
+
+    async fn verify(
+        json: &Self::Kind,
+        expected_domain: &Url,
+        _data: &Data<Self::DataType>,
+    ) -> Result<(), Self::Error> {
+        verify_domains_match(json.id.inner(), expected_domain)?;
+        Ok(())
+    }
+
+    async fn from_json(json: Self::Kind, data: &Data<Self::DataType>) -> Result<Self, Self::Error> {
+        println!(
+            "Received post with content {} and id {}",
+            &json.content, &json.id
+        );
+        let creator = json.attributed_to.dereference(data).await?;
+        let post = DbPost {
+            text: json.content,
+            ap_id: json.id.clone(),
+            creator: json.attributed_to.clone(),
+            local: false,
+        };
+
+        let mention = Mention {
+            href: creator.ap_id.clone().into_inner(),
+            kind: Default::default(),
+        };
+        let note = Note {
+            kind: Default::default(),
+            id: generate_object_id(data.domain())?.into(),
+            attributed_to: data.local_user().ap_id,
+            to: vec![public()],
+            content: format!("Hello {}", creator.name),
+            in_reply_to: Some(json.id.clone()),
+            tag: vec![mention],
+        };
+        CreatePost::send(note, creator.shared_inbox_or_inbox(), data).await?;
+
+        Ok(post)
+    }
+}
diff --git a/fedi/live_federation/utils.rs b/fedi/live_federation/utils.rs
new file mode 100644
index 0000000..0b2b098
--- /dev/null
+++ b/fedi/live_federation/utils.rs
@@ -0,0 +1,13 @@
+use rand::{distributions::Alphanumeric, thread_rng, Rng};
+use url::{ParseError, Url};
+
+/// Just generate random url as object id. In a real project, you probably want to use
+/// an url which contains the database id for easy retrieval (or store the random id in db).
+pub fn generate_object_id(domain: &str) -> Result<Url, ParseError> {
+    let id: String = thread_rng()
+        .sample_iter(&Alphanumeric)
+        .take(7)
+        .map(char::from)
+        .collect();
+    Url::parse(&format!("https://{}/objects/{}", domain, id))
+}