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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");
}
}
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