Use middleware for plugin

.gitignore

@@ -36,4 +36,4 @@ dev_pgdata/
 *.sqldump
 
 # compiled example plugin
-example_plugin/plugin.wasm
+plugins/plugin.wasm

.woodpecker.yml

@@ -229,7 +229,7 @@ steps:
       DO_WRITE_HOSTS_FILE: "1"
     commands:
       - *install_pnpm
-      - apt update && apt install -y bash curl postgresql-client golang tinygo
+      - apt update && apt install -y bash curl postgresql-client golang
       - bash api_tests/prepare-drone-federation-test.sh
       - cd api_tests/
       - pnpm i

Cargo.lock

@@ -3140,8 +3140,6 @@ dependencies = [
  "actix-web",
  "anyhow",
  "bcrypt",
- "extism",
- "extism-convert",
  "futures",
  "lemmy_api_common",
  "lemmy_db_schema",
@@ -3358,6 +3356,7 @@ version = "0.19.4-beta.6"
 dependencies = [
  "activitypub_federation",
  "actix-cors",
+ "actix-http",
  "actix-web",
  "actix-web-prom",
  "chrono",
@@ -3366,6 +3365,8 @@ dependencies = [
  "console-subscriber 0.1.10",
  "diesel",
  "diesel-async",
+ "extism",
+ "extism-convert",
  "futures-util",
  "lemmy_api",
  "lemmy_api_common",
@@ -3383,6 +3384,7 @@ dependencies = [
  "reqwest",
  "reqwest-middleware",
  "reqwest-tracing",
+ "serde",
  "serde_json",
  "serial_test",
  "tokio",

Cargo.toml

@@ -204,7 +204,11 @@ chrono = { workspace = true }
 prometheus = { version = "0.13.3", features = ["process"] }
 serial_test = { workspace = true }
 clap = { workspace = true }
+serde.workspace = true
 actix-web-prom = "0.7.0"
+actix-http = "3.6.0"
+extism = "1.2.0"
+extism-convert = "1.2.0"
 
 [dev-dependencies]
 pretty_assertions = { workspace = true }

api_tests/prepare-drone-federation-test.sh

@@ -74,10 +74,9 @@ LEMMY_CONFIG_LOCATION=./docker/federation/lemmy_delta.hjson \
   target/lemmy_server >$LOG_DIR/lemmy_delta.out 2>&1 &
 
 # plugin setup
-pushd example_plugin
-# TODO: not in ubuntu repos, better to use only `go`
-# TODO: prevent it from creating useless `go` folder in home dir
-tinygo build -o plugin.wasm -target wasi main.go
+pushd plugins
+# need to use tinygo because apparently go has only experimental support for wasm target
+GOPATH=$HOME/.local/share/go tinygo build -o plugin.wasm -target wasi main.go
 popd
 
 echo "start epsilon"

crates/api_crud/Cargo.toml

@@ -31,8 +31,6 @@ anyhow.workspace = true
 serde.workspace = true
 webmention = "0.5.0"
 accept-language = "3.1.0"
-extism = "1.2.0"
-extism-convert = "1.2.0"
 
 [package.metadata.cargo-machete]
 ignored = ["futures"]

crates/api_crud/src/post/create.rs

@@ -1,6 +1,5 @@
 use activitypub_federation::config::Data;
 use actix_web::web::Json;
-use extism::*;
 use lemmy_api_common::{
   build_response::build_post_response,
   context::LemmyContext,
@@ -47,20 +46,16 @@ use lemmy_utils::{
     },
   },
 };
-use serde::Serialize;
-use std::{ffi::OsStr, fs::read_dir};
 use tracing::Instrument;
 use url::Url;
 use webmention::{Webmention, WebmentionError};
 
 #[tracing::instrument(skip(context))]
 pub async fn create_post(
-  mut data: Json<CreatePost>,
+  data: Json<CreatePost>,
   context: Data<LemmyContext>,
   local_user_view: LocalUserView,
 ) -> LemmyResult<Json<PostResponse>> {
-  plugin_hook("api_before_create_post", &mut (*data))?;
-
   let local_site = LocalSite::read(&mut context.pool()).await?;
 
   honeypot_check(&data.honeypot)?;
@@ -205,45 +200,5 @@ pub async fn create_post(
     }
   };
 
-  let mut res = build_post_response(&context, community_id, &local_user_view.person, post_id)
-    .await?
-    .0;
-
-  plugin_hook("api_after_create_post", &mut res)?;
-  Ok(Json(res))
-}
-
-fn load_plugins() -> LemmyResult<Plugin> {
-  // TODO: make dir configurable via env var
-  // TODO: should only read fs once at startup for performance
-  let plugin_paths = read_dir("example_plugin")?;
-
-  let mut wasm_files = vec![];
-  for path in plugin_paths {
-    let path = path?.path();
-    if path.extension() == Some(OsStr::new("wasm")) {
-      wasm_files.push(path);
-    }
-  }
-  let manifest = Manifest::new(wasm_files);
-  let plugin = Plugin::new(manifest, [], true)?;
-  Ok(plugin)
-}
-
-fn plugin_hook<T: Serialize + for<'de> serde::Deserialize<'de> + Clone>(
-  name: &'static str,
-  data: &mut T,
-) -> LemmyResult<()> {
-  let mut plugin = load_plugins()?;
-  if plugin.function_exists(name) {
-    *data = plugin
-      .call::<extism_convert::Json<T>, extism_convert::Json<T>>(name, (*data).clone().into())
-      .map_err(|e| {
-        dbg!(&e);
-        LemmyErrorType::PluginError(e.to_string())
-      })?
-      .0
-      .into();
-  }
-  Ok(())
+  build_post_response(&context, community_id, &local_user_view.person, post_id).await
 }

plugins/main.go

@@ -16,8 +16,8 @@ type CreatePost struct {
 	Custom_thumbnail *string `json:"custom_thumbnail,omitempty"`
   }
 
-//export api_before_create_post
-func api_before_create_post() int32 {
+//export api_before_post_post
+func api_before_post_post() int32 {
 	params := CreatePost{}
 	// use json input helper, which automatically unmarshals the plugin input into your struct
 	err := pdk.InputJSON(&params)

src/api_routes_http.rs

@@ -1,3 +1,4 @@
+use crate::plugin_middleware::PluginMiddleware;
 use actix_web::{guard, web};
 use lemmy_api::{
   comment::{
@@ -139,6 +140,7 @@ use lemmy_utils::rate_limit::RateLimitCell;
 pub fn config(cfg: &mut web::ServiceConfig, rate_limit: &RateLimitCell) {
   cfg.service(
     web::scope("/api/v3")
+      .wrap(PluginMiddleware::new())
       .route("/image_proxy", web::get().to(image_proxy))
       // Site
       .service(

src/lib.rs

@@ -1,5 +1,6 @@
 pub mod api_routes_http;
 pub mod code_migrations;
+pub mod plugin_middleware;
 pub mod prometheus_metrics;
 pub mod root_span_builder;
 pub mod scheduled_tasks;

src/plugin_middleware.rs

@@ -0,0 +1,120 @@
+use actix_http::h1::Payload;
+use actix_web::{
+  body::MessageBody,
+  dev::{forward_ready, Service, ServiceRequest, ServiceResponse, Transform},
+  web::Bytes,
+  Error,
+};
+use core::future::Ready;
+use extism::{Manifest, Plugin};
+use futures_util::future::LocalBoxFuture;
+use lemmy_utils::{error::LemmyResult, LemmyErrorType};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::{ffi::OsStr, fs::read_dir, future::ready, rc::Rc};
+use tracing::info;
+
+#[derive(Clone)]
+pub struct PluginMiddleware {}
+
+impl PluginMiddleware {
+  pub fn new() -> Self {
+    PluginMiddleware {}
+  }
+}
+impl<S, B> Transform<S, ServiceRequest> for PluginMiddleware
+where
+  S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
+  S::Future: 'static,
+  B: MessageBody + 'static,
+{
+  type Response = ServiceResponse<B>;
+  type Error = Error;
+  type Transform = SessionService<S>;
+  type InitError = ();
+  type Future = Ready<Result<Self::Transform, Self::InitError>>;
+
+  fn new_transform(&self, service: S) -> Self::Future {
+    ready(Ok(SessionService {
+      service: Rc::new(service),
+    }))
+  }
+}
+
+pub struct SessionService<S> {
+  service: Rc<S>,
+}
+
+impl<S, B> Service<ServiceRequest> for SessionService<S>
+where
+  S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
+  S::Future: 'static,
+  B: 'static,
+{
+  type Response = ServiceResponse<B>;
+  type Error = Error;
+  type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;
+
+  forward_ready!(service);
+
+  fn call(&self, mut service_req: ServiceRequest) -> Self::Future {
+    let svc = self.service.clone();
+
+    Box::pin(async move {
+      let method = service_req.method();
+      let path = service_req.path().replace("/api/v3/", "").replace("/", "_");
+      // TODO: naming can be a bit silly, `POST /api/v3/post` becomes `api_before_post_post`
+      let plugin_hook = format!("api_before_{method}_{path}").to_lowercase();
+      info!("Calling plugin hook {}", &plugin_hook);
+      if let Some(mut plugins) = load_plugins()? {
+        if plugins.function_exists(&plugin_hook) {
+          let payload = service_req.extract::<Bytes>().await?;
+
+          let mut json: Value = serde_json::from_slice(&payload.to_vec())?;
+          call_plugin(plugins, &plugin_hook, &mut json)?;
+
+          let (_, mut new_payload) = Payload::create(true);
+          new_payload.unread_data(Bytes::from(serde_json::to_vec_pretty(&json)?));
+          service_req.set_payload(new_payload.into());
+        }
+      }
+      let res = svc.call(service_req).await?;
+      Ok(res)
+    })
+  }
+}
+
+fn load_plugins() -> LemmyResult<Option<Plugin>> {
+  // TODO: make dir configurable via env var
+  // TODO: should only read fs once at startup for performance
+  let plugin_paths = read_dir("plugins")?;
+
+  let mut wasm_files = vec![];
+  for path in plugin_paths {
+    let path = path?.path();
+    if path.extension() == Some(OsStr::new("wasm")) {
+      wasm_files.push(path);
+    }
+  }
+  if !wasm_files.is_empty() {
+    // TODO: what if theres more than one plugin for the same hook?
+    let manifest = Manifest::new(wasm_files);
+    let plugin = Plugin::new(manifest, [], true)?;
+    Ok(Some(plugin))
+  } else {
+    Ok(None)
+  }
+}
+
+pub fn call_plugin<T: Serialize + for<'de> Deserialize<'de> + Clone>(
+  mut plugins: Plugin,
+  name: &str,
+  data: &mut T,
+) -> LemmyResult<()> {
+  *data = plugins
+    .call::<extism_convert::Json<T>, extism_convert::Json<T>>(name, (*data).clone().into())
+    .map_err(|e| LemmyErrorType::PluginError(e.to_string()))?
+    .0
+    .into();
+  Ok(())
+}