WIP Refactor, code is broken

1 files changed, 201 insertions, 0 deletions

diff --git a/src/imap/session.rs b/src/imap/session.rs
new file mode 100644
index 0000000..2035634
--- /dev/null
+++ b/src/imap/session.rs
@@ -0,0 +1,201 @@
+use std::sync::Arc;
+
+use anyhow::Error;
+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 imap_codec::types::response::{Capability, Code, Data, Response as ImapRes, Status};
+use tokio::sync::mpsc::error::TrySendError;
+use tokio::sync::{mpsc, oneshot};
+
+use crate::command::{anonymous,authenticated,selected};
+use crate::login::Credentials;
+use crate::mailbox::Mailbox;
+use crate::LoginProvider;
+
+/* 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<Result<Response, BalError>>,
+}
+
+//-----
+
+pub struct Manager {
+    tx: mpsc::Sender<Message>,
+}
+
+impl Manager {
+    pub fn new(login_provider: ArcLoginProvider) -> Self {
+        let (tx, rx) = mpsc::channel(MAX_PIPELINED_COMMANDS);
+        tokio::spawn(async move {
+            let mut instance = Instance::new(login_provider, rx);
+            instance.start().await;
+        });
+        Self { tx }
+    }
+
+    pub fn process(&self, req: Request) -> BoxFuture<'static, Result<Response, BalError>> {
+        let (tx, rx) = oneshot::channel();
+        let tag = req.tag.clone();
+        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 {
+                    Status::bad(Some(tag), None, "Too fast! Send less pipelined requests!")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(|e| BalError::Text(e.to_string()))
+                }
+                .boxed()
+            }
+            Err(TrySendError::Closed(_)) => {
+                return async {
+                    Status::bad(Some(tag), None, "The session task has exited")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(|e| BalError::Text(e.to_string()))
+                }
+                .boxed()
+            }
+        };
+
+        // @FIXME add a timeout, handle a session that fails.
+        async {
+            match rx.await {
+                Ok(r) => r,
+                Err(e) => {
+                    tracing::warn!("Got error {:#?}", e);
+                    Status::bad(Some(tag), None, "No response from the session handler")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(|e| BalError::Text(e.to_string()))
+                }
+            }
+        }
+        .boxed()
+    }
+}
+
+//-----
+
+pub struct Context<'a> {
+    req: &'a Request,
+    state: &'a mut flow::State,
+    login: ArcLoginProvider,
+}
+
+pub struct Instance {
+    rx: mpsc::Receiver<Message>,
+
+    pub login_provider: ArcLoginProvider,
+    pub state: flow::State,
+}
+impl Instance {
+    fn new(
+        login_provider: ArcLoginProvider,
+        rx: mpsc::Receiver<Message>,
+    ) -> Self {
+        Self {
+            login_provider,
+            rx,
+            state: flow::State::NotAuthenticated,
+        }
+    }
+
+    //@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 ctx = Context { req: &msg.req, state: &mut self.state, login: self.login_provider };
+
+            // Command behavior is modulated by the state.
+            // To prevent state error, we handle the same command in separate code path depending
+            // on the State.
+            let cmd_res =  match self.state {
+                flow::State::NotAuthenticated => anonymous::dispatch(ctx).await, 
+                flow::State::Authenticated(user) => authenticated::dispatch(ctx).await,
+                flow::State::Selected(user, mailbox) => selected::dispatch(ctx).await,
+                flow::State::Logout => Status::bad(Some(ctx.req.tag.clone()), None, "No commands are allowed in the LOGOUT state.")
+                    .map(|s| vec![ImapRes::Status(s)])
+                    .map_err(Error::msg),
+            };
+
+/*
+
+                match req.body {
+                    CommandBody::Capability => anonymous::capability().await,
+                    CommandBody::Login { username, password } => anonymous::login(self.login_provider, username, password).await.and_then(|(user, response)| {
+                        self.state.authenticate(user)?;
+                        Ok(response)
+                    },
+                    _ => Status::no(Some(msg.req.tag.clone()), None, "This command is not available in the ANONYMOUS state.")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(Error::msg),
+
+                },
+                flow::State::Authenticated(user) => match req.body {
+                    CommandBody::Capability => anonymous::capability().await, // we use the same implem for now
+                    CommandBody::Lsub { reference, mailbox_wildcard, } => authenticated::lsub(reference, mailbox_wildcard).await,
+                    CommandBody::List { reference, mailbox_wildcard, } => authenticated::list(reference, mailbox_wildcard).await,
+                    CommandBody::Select { mailbox } => authenticated::select(user, mailbox).await.and_then(|(mailbox, response)| {
+                        self.state.select(mailbox);
+                        Ok(response)
+                    }),
+                    _ => Status::no(Some(msg.req.tag.clone()), None, "This command is not available in the AUTHENTICATED state.")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(Error::msg),
+                },
+                flow::State::Selected(user, mailbox) => match req.body {
+                    CommandBody::Capability => anonymous::capability().await, // we use the same implem for now
+                    CommandBody::Fetch { sequence_set, attributes, uid, } => selected::fetch(sequence_set, attributes, uid).await,
+                    _ => Status::no(Some(msg.req.tag.clone()), None, "This command is not available in the SELECTED state.")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(Error::msg),
+                },
+                flow::State::Logout => Status::bad(Some(msg.req.tag.clone()), None, "No commands are allowed in the LOGOUT state.")
+                    .map(|s| vec![ImapRes::Status(s)])
+                    .map_err(Error::msg),
+            }
+            */
+
+            let imap_res = match cmd_res {
+                Ok(new_state, imap_res) => {
+                    self.state = new_state;
+                    Ok(imap_res)
+                },
+                Err(e) if Ok(be) = e.downcast::<BalError>() => Err(be),
+                Err(e) => {
+                    tracing::warn!(error=%e, "internal.error");
+                    Ok(Status::bad(Some(msg.req.tag.clone()), None, "Internal error")
+                        .map(|s| vec![ImapRes::Status(s)])
+                        .map_err(|e| BalError::Text(e.to_string())))
+                }
+            };
+
+            //@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(imap_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");
+    }
+}