endpoint: use authorized_fetch for remote_actor validation

src/endpoint.rs

@@ -9,11 +9,12 @@ use axum::{
 
 use http_digest_headers::{DigestHeader};
 
-use sigh::{Signature, PublicKey, Key};
+use sigh::{Signature, PublicKey, Key, PrivateKey};
 
 
-use crate::fetch::fetch;
+use crate::fetch::authorized_fetch;
 use crate::activitypub::Actor;
+use crate::error::Error;
 
 const SIGNATURE_HEADERS_REQUIRED: &[&str] = &[
     "(request-target)",
@@ -21,20 +22,14 @@ const SIGNATURE_HEADERS_REQUIRED: &[&str] = &[
     "digest",
 ];
 
-#[derive(Clone, Debug)]
-pub struct Endpoint {
+pub struct Endpoint<'a> {
     pub payload: serde_json::Value,
-    pub actor: Actor,
+    signature: Signature<'a>,
+    remote_actor_uri: String,
 }
 
-// impl Endpoint {
-//     pub fn parse<T: DeserializeOwned>(self) -> Result<T, serde_json::Error> {
-//         serde_json::from_value(self.payload)
-//     }
-// }
-
 #[async_trait]
-impl<S, B> FromRequest<S, B> for Endpoint
+impl<'a, S, B> FromRequest<S, B> for Endpoint<'a>
 where
     B: HttpBody + Send + 'static,
     B::Data: Send,
@@ -95,27 +90,32 @@ where
         // parse body
         let payload: serde_json::Value = serde_json::from_slice(&bytes)
             .map_err(|_| (StatusCode::BAD_REQUEST, "Error parsing JSON".to_string()))?;
-        let actor_uri = if let Some(serde_json::Value::String(actor_uri)) = payload.get("actor") {
-            actor_uri
+        let remote_actor_uri = if let Some(serde_json::Value::String(actor_uri)) = payload.get("actor") {
+            actor_uri.to_string()
         } else {
             return Err((StatusCode::BAD_REQUEST, "Actor missing".to_string()));
         };
 
-        // validate actor
-        let client = Arc::from_ref(state);
-        let actor: Actor =
-            serde_json::from_value(
-                fetch(&client, actor_uri).await
-                    .map_err(|e| (StatusCode::BAD_GATEWAY, format!("{}", e)))?
-            ).map_err(|e| (StatusCode::BAD_GATEWAY, format!("Invalid actor: {}", e)))?;
-        let public_key = PublicKey::from_pem(actor.public_key.pem.as_bytes())
-            .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("{:?}", e)))?;
-        if !(signature.verify(&public_key)
-            .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("{:?}", e)))?)
-        {
-            return Err((StatusCode::BAD_REQUEST, "Signature verification failed".to_string()));
-        }
-        
-        return Ok(Endpoint { payload, actor });
+        return Ok(Endpoint { payload, signature, remote_actor_uri });
+    }
+}
+
+impl<'a> Endpoint<'a> {
+    /// Validates the requesting actor
+    pub async fn remote_actor(
+        &self,
+        client: &reqwest::Client,
+        key_id: &str,
+        private_key: &PrivateKey,
+    ) -> Result<Actor, Error> {
+        let remote_actor: Actor = serde_json::from_value(
+            authorized_fetch(&client, &self.remote_actor_uri, key_id, private_key).await?
+        )?;
+        let public_key = PublicKey::from_pem(remote_actor.public_key.pem.as_bytes())?;
+        if ! (self.signature.verify(&public_key)?) {
+            return Err(Error::SignatureFail);
+        }
+
+        Ok(remote_actor)
     }
 }

src/error.rs

@@ -6,6 +6,8 @@ pub enum Error {
     Json(#[from] serde_json::Error),
     #[error("Signature error")]
     Signature(#[from] sigh::Error),
+    #[error("Signature verification failure")]
+    SignatureFail,
     #[error("HTTP request error")]
     HttpReq(#[from] http::Error),
     #[error("HTTP client error")]

src/fetch.rs

@@ -3,18 +3,6 @@ use serde::de::DeserializeOwned;
 use sigh::{PrivateKey, SigningConfig, alg::RsaSha256};
 use crate::{digest, error::Error};
 
-pub async fn fetch<T>(client: &reqwest::Client, url: &str) -> Result<T, reqwest::Error>
-where
-    T: DeserializeOwned,
-{
-    client.get(url)
-        .header("accept", "application/activity+json")
-        .send()
-        .await?
-        .json()
-        .await
-}
-
 pub async fn authorized_fetch<T>(
     client: &reqwest::Client,
     uri: &str,

src/main.rs

@@ -120,7 +120,7 @@ async fn get_instance_actor(
 async fn post_tag_relay(
     axum::extract::State(state): axum::extract::State<State>,
     Path(tag): Path<String>,
-    endpoint: endpoint::Endpoint
+    endpoint: endpoint::Endpoint<'_>
 ) -> Response {
     let target = actor::Actor {
         host: state.hostname.clone(),
@@ -132,7 +132,7 @@ async fn post_tag_relay(
 async fn post_instance_relay(
     axum::extract::State(state): axum::extract::State<State>,
     Path(instance): Path<String>,
-    endpoint: endpoint::Endpoint
+    endpoint: endpoint::Endpoint<'_>
 ) -> Response {
     let target = actor::Actor {
         host: state.hostname.clone(),
@@ -143,9 +143,19 @@ async fn post_instance_relay(
 
 async fn post_relay(
     state: State,
-    endpoint: endpoint::Endpoint,
+    endpoint: endpoint::Endpoint<'_>,
     target: actor::Actor
 ) -> Response {
+    let remote_actor = match endpoint.remote_actor(&state.client, &target.key_id(), &state.priv_key).await {
+        Ok(remote_actor) => remote_actor,
+        Err(e) => {
+            track_request("POST", "relay", "bad_actor");
+            return (
+                StatusCode::BAD_REQUEST,
+                format!("Bad actor: {:?}", e)
+            ).into_response();
+        }
+    };
     let action = match serde_json::from_value::<activitypub::Action<serde_json::Value>>(endpoint.payload.clone()) {
         Ok(action) => action,
         Err(e) => {
@@ -168,12 +178,12 @@ async fn post_relay(
                 jsonld_context: serde_json::Value::String("https://www.w3.org/ns/activitystreams".to_string()),
                 action_type: "Accept".to_string(),
                 actor: target.uri(),
-                to: Some(json!(endpoint.actor.id.clone())),
+                to: Some(json!(remote_actor.id.clone())),
                 id: action.id,
                 object: Some(endpoint.payload),
             };
             let result = send::send(
-                client.as_ref(), &endpoint.actor.inbox,
+                client.as_ref(), &remote_actor.inbox,
                 &target.key_id(),
                 &priv_key,
                 &accept,
@@ -181,8 +191,8 @@ async fn post_relay(
             match result {
                 Ok(()) => {
                     match state.database.add_follow(
-                        &endpoint.actor.id,
-                        &endpoint.actor.inbox,
+                        &remote_actor.id,
+                        &remote_actor.inbox,
                         &target.uri(),
                     ).await {
                         Ok(()) => {
@@ -208,7 +218,7 @@ async fn post_relay(
         ).into_response()
     } else if action.action_type == "Undo" && object_type == Some("Follow".to_string()) {
         match state.database.del_follow(
-            &endpoint.actor.id,
+            &remote_actor.id,
             &target.uri(),
         ).await {
             Ok(()) => {