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>, } pub struct Manager { tx: mpsc::Sender, } //@FIXME we should garbage collect the Instance when the Manager is destroyed. impl Manager { pub fn new(mailstore: Arc) -> 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> { 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 { match rx.await { Ok(r) => r, Err(e) => { tracing::warn!("Got error {:#?}", e); Response::bad("No response from the session handler") }, } }.boxed() } } pub struct Instance { rx: mpsc::Receiver, pub mailstore: Arc, pub creds: Option, pub selected: Option, } impl Instance { fn new(mailstore: Arc, rx: mpsc::Receiver) -> 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 res = 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 I think we should quit this thread on error and having our manager watch it, // and then abort the session as it is corrupted. msg.tx.send(res).unwrap_or_else(|e| tracing::warn!("failed to send imap response to manager: {:#?}", e)); } //@FIXME add more info about the runner tracing::debug!("exiting runner"); } }