From 0f3bf858a3abb14a6300cef965d5d6c2e9c9e35e Mon Sep 17 00:00:00 2001
From: Manos Pitsidianakis <el13635@mail.ntua.gr>
Date: Mon, 24 Aug 2020 12:01:28 +0300
Subject: [PATCH] melib/imap: impl UNSELECT via nonexistent mailbox

---
 melib/src/backends/imap/connection.rs      | 72 ++++++++++++++--------
 melib/src/backends/imap/protocol_parser.rs |  1 +
 2 files changed, 48 insertions(+), 25 deletions(-)

diff --git a/melib/src/backends/imap/connection.rs b/melib/src/backends/imap/connection.rs
index 0ba2e2054..7379cea00 100644
--- a/melib/src/backends/imap/connection.rs
+++ b/melib/src/backends/imap/connection.rs
@@ -589,6 +589,14 @@ impl ImapConnection {
                             ret.push_str(&response);
                             return r.into();
                         }
+                        ImapResponse::No(ref response_code)
+                            if required_responses.intersects(RequiredResponses::NO_REQUIRED) =>
+                        {
+                            debug!(
+                                "Received expected NO response: {:?} {:?}",
+                                response_code, response
+                            );
+                        }
                         ImapResponse::No(ref response_code) => {
                             //FIXME return error
                             debug!("Received NO response: {:?} {:?}", response_code, response);
@@ -731,31 +739,45 @@ impl ImapConnection {
 
     pub async fn unselect(&mut self) -> Result<()> {
         match self.stream.as_mut()?.current_mailbox.take() {
-            MailboxSelection::Examine(mailbox_hash) |
-            MailboxSelection::Select(mailbox_hash) =>{
-            let mut response = String::with_capacity(8 * 1024);
-            if self
-                .uid_store
-                .capabilities
-                .lock()
-                .unwrap()
-                .iter()
-                .any(|cap| cap.eq_ignore_ascii_case(b"UNSELECT"))
-            {
-                self.send_command(b"UNSELECT").await?;
-                self.read_response(&mut response, RequiredResponses::empty())
-                    .await?;
-            } else {
-                /* `RFC3691 - UNSELECT Command` states: "[..] IMAP4 provides this
-                 * functionality (via a SELECT command with a nonexistent mailbox name or
-                 * reselecting the same mailbox with EXAMINE command)[..]
-                 */
-                
-                self.select_mailbox(mailbox_hash, &mut response, true).await?;
-                self.examine_mailbox(mailbox_hash, &mut response, true).await?;
-            }
-        },
-        MailboxSelection::None => {},
+            MailboxSelection::Examine(_) |
+                MailboxSelection::Select(_) => {
+                    let mut response = String::with_capacity(8 * 1024);
+                    if self
+                        .uid_store
+                            .capabilities
+                            .lock()
+                            .unwrap()
+                            .iter()
+                            .any(|cap| cap.eq_ignore_ascii_case(b"UNSELECT"))
+                    {
+                        self.send_command(b"UNSELECT").await?;
+                        self.read_response(&mut response, RequiredResponses::empty())
+                            .await?;
+                        } else {
+                            /* `RFC3691 - UNSELECT Command` states: "[..] IMAP4 provides this
+                             * functionality (via a SELECT command with a nonexistent mailbox name or
+                             * reselecting the same mailbox with EXAMINE command)[..]
+                             */
+                            let mut nonexistent = "blurdybloop".to_string();
+                            {
+                                let mailboxes = self.uid_store.mailboxes.lock().await;
+                                while mailboxes.values().any(|m| m.imap_path() == &nonexistent) {
+                                    nonexistent.push('p');
+                                }
+                            }
+                            self.send_command(
+                                format!(
+                                    "SELECT \"{}\"",
+                                    nonexistent
+                                )
+                                .as_bytes(),
+                            )
+                                .await?;
+                            self.read_response(&mut response, RequiredResponses::NO_REQUIRED)
+                                .await?;
+                        }
+                }
+            MailboxSelection::None => {},
         }
         Ok(())
     }
diff --git a/melib/src/backends/imap/protocol_parser.rs b/melib/src/backends/imap/protocol_parser.rs
index af7fca19d..444c6df07 100644
--- a/melib/src/backends/imap/protocol_parser.rs
+++ b/melib/src/backends/imap/protocol_parser.rs
@@ -53,6 +53,7 @@ bitflags! {
         const EXPUNGE             = 0b0001_0000_0000_0000;
         const SEARCH              = 0b0010_0000_0000_0000;
         const FETCH               = 0b0100_0000_0000_0000;
+        const NO_REQUIRED         = 0b1000_0000_0000_0000;
         const CAPABILITY_REQUIRED = Self::CAPABILITY.bits;
         const LOGOUT_REQUIRED     = Self::BYE.bits;
         const SELECT_REQUIRED     = Self::FLAGS.bits | Self::EXISTS.bits | Self::RECENT.bits | Self::UNSEEN.bits | Self::PERMANENTFLAGS.bits | Self::UIDNEXT.bits | Self::UIDVALIDITY.bits;