It compiles

src/command.rs

@@ -1,5 +1,3 @@
-use std::sync::{Arc, Mutex};
-
 use boitalettres::errors::Error as BalError;
 use boitalettres::proto::{Request, Response};
 use imap_codec::types::core::{Tag, AString};
@@ -10,15 +8,15 @@ use imap_codec::types::fetch_attributes::MacroOrFetchAttributes;
 
 use crate::mailstore::Mailstore;
 use crate::mailbox::Mailbox;
-use crate::service::Session;
+use crate::session;
 
 pub struct Command<'a> {
     tag: Tag,
-    session: &'a mut Session,
+    session: &'a mut session::Instance,
 }
 
 impl<'a> Command<'a> {
-    pub fn new(tag: Tag, session: &'a mut Session) -> Self {
+    pub fn new(tag: Tag, session: &'a mut session::Instance) -> Self {
         Self { tag, session }
     }
 

src/main.rs

@@ -7,6 +7,7 @@ mod mailbox;
 mod mailstore;
 mod server;
 mod service;
+mod session;
 mod time;
 mod uidindex;
 

src/service.rs

@@ -1,4 +1,4 @@
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use std::task::{Context, Poll};
 
 use anyhow::Result;
@@ -7,17 +7,10 @@ use boitalettres::errors::Error as BalError;
 use boitalettres::proto::{Request, Response};
 use futures::future::BoxFuture;
 use futures::future::FutureExt;
-use imap_codec::types::command::CommandBody;
-use tokio::sync::mpsc;
-use tokio::sync::mpsc::error::TrySendError;
 use tower::Service;
 
-use crate::command;
-use crate::login::Credentials;
 use crate::mailstore::Mailstore;
-use crate::mailbox::Mailbox;
+use crate::session;
-
-const MAX_PIPELINED_COMMANDS: usize = 10;
 
 pub struct Instance {
     pub mailstore: Arc<Mailstore>,
@@ -39,21 +32,16 @@ impl<'a> Service<&'a AddrStream> for Instance {
     fn call(&mut self, addr: &'a AddrStream) -> Self::Future {
         tracing::info!(remote_addr = %addr.remote_addr, local_addr = %addr.local_addr, "accept");
         let ms = self.mailstore.clone();
-        Box::pin(async { Ok(Connection::new(ms)) })
+        async { Ok(Connection::new(ms)) }.boxed()
     }
 }
 
 pub struct Connection {
-    pub tx: mpsc::Sender<Request>,
+    session: session::Manager,
 }
 impl Connection {
     pub fn new(mailstore: Arc<Mailstore>) -> Self {
-        let (tx, mut rx) = mpsc::channel(MAX_PIPELINED_COMMANDS);
+        Self { session: session::Manager::new(mailstore) }
-        tokio::spawn(async move { 
-            let mut session = Session::new(mailstore, rx);
-            session.run().await; 
-        });
-        Self { tx }
     }
 }
 impl Service<Request> for Connection {
@@ -67,41 +55,9 @@ impl Service<Request> for Connection {
 
     fn call(&mut self, req: Request) -> Self::Future {
         tracing::debug!("Got request: {:#?}", req);
-        match self.tx.try_send(req) {
+        self.session.process(req)
-            Ok(()) => return async { Response::ok("Ok") }.boxed(),
-            Err(TrySendError::Full(_)) => return async { Response::bad("Too fast! Send less pipelined requests!") }.boxed(),
-            Err(TrySendError::Closed(_)) => return async { Response::bad("The session task has exited") }.boxed(),
-        }
-
-        // send a future that await here later a oneshot command
     }
 }
 
-pub struct Session {
-    pub mailstore: Arc<Mailstore>,
-    pub creds: Option<Credentials>,
-    pub selected: Option<Mailbox>,
-    rx: mpsc::Receiver<Request>,
-}
 
-impl Session {
-    pub fn new(mailstore: Arc<Mailstore>, rx: mpsc::Receiver<Request>) -> Self {
-        Self { mailstore, rx, creds: None, selected: None, }
-    }
-
-    pub async fn run(&mut self) {
-        while let Some(req) = self.rx.recv().await {
-             let mut cmd = command::Command::new(req.tag, self);
-             let _ = match req.body {
-                CommandBody::Capability => cmd.capability().await,
-                CommandBody::Login { username, password } => cmd.login(username, password).await,
-                CommandBody::Lsub { reference, mailbox_wildcard } => cmd.lsub(reference, mailbox_wildcard).await,
-                CommandBody::List { reference, mailbox_wildcard } => cmd.list(reference, mailbox_wildcard).await,
-                CommandBody::Select { mailbox } => cmd.select(mailbox).await,
-                CommandBody::Fetch { sequence_set, attributes, uid } => cmd.fetch(sequence_set, attributes, uid).await,
-               _ => Response::bad("Error in IMAP command received by server."),
-            };
-        }
-    }
-}
 

src/session.rs

@@ -0,0 +1,102 @@
+use std::sync::Arc;
+
+use boitalettres::proto::{Request, Response};
+use boitalettres::errors::Error as BalError;
+use imap_codec::types::command::CommandBody;
+use tokio::sync::{oneshot,mpsc};
+use tokio::sync::mpsc::error::TrySendError;
+use futures::future::BoxFuture;
+use futures::future::FutureExt;
+
+use crate::command;
+use crate::login::Credentials;
+use crate::mailstore::Mailstore;
+use crate::mailbox::Mailbox;
+
+/* This constant configures backpressure in the system,
+ * or more specifically, how many pipelined messages are allowed
+ * before refusing them 
+ */
+const MAX_PIPELINED_COMMANDS: usize = 10;
+
+struct Message {
+    req: Request,
+    tx: oneshot::Sender<Response>,
+}
+
+pub struct Manager {
+    tx: mpsc::Sender<Message>,
+}
+
+//@FIXME we should garbage collect the Instance when the Manager is destroyed.
+impl Manager {
+    pub fn new(mailstore: Arc<Mailstore>) -> Self {
+        let (tx, mut rx) = mpsc::channel(MAX_PIPELINED_COMMANDS);
+        tokio::spawn(async move { 
+            let mut instance = Instance::new(mailstore, rx);
+            instance.start().await;
+        });
+        Self { tx }
+    }
+
+    pub fn process(&self, req: Request) -> BoxFuture<'static, Result<Response, BalError>> {
+        let (tx, rx) = oneshot::channel();
+        let msg = Message { req, tx };
+
+        // We use try_send on a bounded channel to protect the daemons from DoS.
+        // Pipelining requests in IMAP are a special case: they should not occure often
+        // and in a limited number (like 3 requests). Someone filling the channel
+        // will probably be malicious so we "rate limit" them.
+        match self.tx.try_send(msg) {
+            Ok(()) => (),
+            Err(TrySendError::Full(_)) => return async { Response::bad("Too fast! Send less pipelined requests!") }.boxed(),
+            Err(TrySendError::Closed(_)) => return async { Response::bad("The session task has exited") }.boxed(),
+        };
+
+        // @FIXME add a timeout, handle a session that fails.
+        async {
+            rx.await.or_else(|e| {
+                tracing::warn!("Got error {:#?}", e);
+                Response::bad("No response from the session handler")
+            })
+        }.boxed()
+    }
+}
+
+pub struct Instance {
+    rx: mpsc::Receiver<Message>,
+
+    pub mailstore: Arc<Mailstore>, 
+    pub creds: Option<Credentials>,
+    pub selected: Option<Mailbox>,
+}
+impl Instance {
+    fn new(mailstore: Arc<Mailstore>, rx: mpsc::Receiver<Message>) -> Self {
+        Self { mailstore, rx, creds: None, selected: None, }
+    }
+
+    //@FIXME add a function that compute the runner's name from its local info
+    // to ease debug
+    // fn name(&self) -> String { }
+
+    async fn start(&mut self) {
+        //@FIXME add more info about the runner
+        tracing::debug!("starting runner");
+
+        while let Some(msg) = self.rx.recv().await {
+            let mut cmd = command::Command::new(msg.req.tag, self);
+            let _ = match msg.req.body {
+                CommandBody::Capability => cmd.capability().await,
+                CommandBody::Login { username, password } => cmd.login(username, password).await,
+                CommandBody::Lsub { reference, mailbox_wildcard } => cmd.lsub(reference, mailbox_wildcard).await,
+                CommandBody::List { reference, mailbox_wildcard } => cmd.list(reference, mailbox_wildcard).await,
+                CommandBody::Select { mailbox } => cmd.select(mailbox).await,
+                CommandBody::Fetch { sequence_set, attributes, uid } => cmd.fetch(sequence_set, attributes, uid).await,
+                _ => Response::bad("Error in IMAP command received by server."),
+            };
+        }
+
+        //@FIXME add more info about the runner
+        tracing::debug!("exiting runner");
+    }
+}