use std::collections::{BTreeMap, HashMap}; use std::sync::{Arc, Weak}; use anyhow::{anyhow, bail, Result}; use k2v_client::{CausalityToken, K2vClient, K2vValue}; use lazy_static::lazy_static; use serde::{Deserialize, Serialize}; use tokio::sync::watch; use crate::cryptoblob::{open_deserialize, seal_serialize}; use crate::login::{Credentials, StorageCredentials}; use crate::mail::incoming::incoming_mail_watch_process; use crate::mail::mailbox::Mailbox; use crate::mail::uidindex::ImapUidvalidity; use crate::mail::unique_ident::{gen_ident, UniqueIdent}; use crate::storage; use crate::time::now_msec; pub const MAILBOX_HIERARCHY_DELIMITER: char = '.'; /// INBOX is the only mailbox that must always exist. /// It is created automatically when the account is created. /// IMAP allows the user to rename INBOX to something else, /// in this case all messages from INBOX are moved to a mailbox /// with the new name and the INBOX mailbox still exists and is empty. /// In our implementation, we indeed move the underlying mailbox /// to the new name (i.e. the new name has the same id as the previous /// INBOX), and we create a new empty mailbox for INBOX. pub const INBOX: &str = "INBOX"; const MAILBOX_LIST_PK: &str = "mailboxes"; const MAILBOX_LIST_SK: &str = "list"; pub struct User { pub username: String, pub creds: Credentials, pub k2v: K2vClient, pub mailboxes: std::sync::Mutex>>, tx_inbox_id: watch::Sender>, } impl User { pub async fn new(username: String, creds: Credentials) -> Result> { let cache_key = (username.clone(), creds.storage.clone()); { let cache = USER_CACHE.lock().unwrap(); if let Some(u) = cache.get(&cache_key).and_then(Weak::upgrade) { return Ok(u); } } let user = Self::open(username, creds).await?; let mut cache = USER_CACHE.lock().unwrap(); if let Some(concurrent_user) = cache.get(&cache_key).and_then(Weak::upgrade) { drop(user); Ok(concurrent_user) } else { cache.insert(cache_key, Arc::downgrade(&user)); Ok(user) } } /// Lists user's available mailboxes pub async fn list_mailboxes(&self) -> Result> { let (list, _ct) = self.load_mailbox_list().await?; Ok(list.existing_mailbox_names()) } /// Opens an existing mailbox given its IMAP name. pub async fn open_mailbox(&self, name: &str) -> Result>> { let (mut list, ct) = self.load_mailbox_list().await?; eprintln!("List of mailboxes:"); for ent in list.0.iter() { eprintln!(" - {:?}", ent); } if let Some((uidvalidity, Some(mbid))) = list.get_mailbox(name) { let mb = self.open_mailbox_by_id(mbid, uidvalidity).await?; let mb_uidvalidity = mb.current_uid_index().await.uidvalidity; if mb_uidvalidity > uidvalidity { list.update_uidvalidity(name, mb_uidvalidity); self.save_mailbox_list(&list, ct).await?; } Ok(Some(mb)) } else { Ok(None) } } /// Check whether mailbox exists pub async fn has_mailbox(&self, name: &str) -> Result { let (list, _ct) = self.load_mailbox_list().await?; Ok(list.has_mailbox(name)) } /// Creates a new mailbox in the user's IMAP namespace. pub async fn create_mailbox(&self, name: &str) -> Result<()> { if name.ends_with(MAILBOX_HIERARCHY_DELIMITER) { bail!("Invalid mailbox name: {}", name); } let (mut list, ct) = self.load_mailbox_list().await?; match list.create_mailbox(name) { CreatedMailbox::Created(_, _) => { self.save_mailbox_list(&list, ct).await?; Ok(()) } CreatedMailbox::Existed(_, _) => Err(anyhow!("Mailbox {} already exists", name)), } } /// Deletes a mailbox in the user's IMAP namespace. pub async fn delete_mailbox(&self, name: &str) -> Result<()> { if name == INBOX { bail!("Cannot delete INBOX"); } let (mut list, ct) = self.load_mailbox_list().await?; if list.has_mailbox(name) { // TODO: actually delete mailbox contents list.set_mailbox(name, None); self.save_mailbox_list(&list, ct).await?; Ok(()) } else { bail!("Mailbox {} does not exist", name); } } /// Renames a mailbox in the user's IMAP namespace. pub async fn rename_mailbox(&self, old_name: &str, new_name: &str) -> Result<()> { let (mut list, ct) = self.load_mailbox_list().await?; if old_name.ends_with(MAILBOX_HIERARCHY_DELIMITER) { bail!("Invalid mailbox name: {}", old_name); } if new_name.ends_with(MAILBOX_HIERARCHY_DELIMITER) { bail!("Invalid mailbox name: {}", new_name); } if old_name == INBOX { list.rename_mailbox(old_name, new_name)?; if !self.ensure_inbox_exists(&mut list, &ct).await? { self.save_mailbox_list(&list, ct).await?; } } else { let names = list.existing_mailbox_names(); let old_name_w_delim = format!("{}{}", old_name, MAILBOX_HIERARCHY_DELIMITER); let new_name_w_delim = format!("{}{}", new_name, MAILBOX_HIERARCHY_DELIMITER); if names .iter() .any(|x| x == new_name || x.starts_with(&new_name_w_delim)) { bail!("Mailbox {} already exists", new_name); } for name in names.iter() { if name == old_name { list.rename_mailbox(name, new_name)?; } else if let Some(tail) = name.strip_prefix(&old_name_w_delim) { let nnew = format!("{}{}", new_name_w_delim, tail); list.rename_mailbox(name, &nnew)?; } } self.save_mailbox_list(&list, ct).await?; } Ok(()) } // ---- Internal user & mailbox management ---- async fn open(username: String, creds: Credentials) -> Result> { let k2v = creds.k2v_client()?; let (tx_inbox_id, rx_inbox_id) = watch::channel(None); let user = Arc::new(Self { username, creds: creds.clone(), k2v, tx_inbox_id, mailboxes: std::sync::Mutex::new(HashMap::new()), }); // Ensure INBOX exists (done inside load_mailbox_list) user.load_mailbox_list().await?; tokio::spawn(incoming_mail_watch_process( Arc::downgrade(&user), user.creds.clone(), rx_inbox_id, )); Ok(user) } pub(super) async fn open_mailbox_by_id( &self, id: UniqueIdent, min_uidvalidity: ImapUidvalidity, ) -> Result> { { let cache = self.mailboxes.lock().unwrap(); if let Some(mb) = cache.get(&id).and_then(Weak::upgrade) { return Ok(mb); } } let mb = Arc::new(Mailbox::open(&self.creds, id, min_uidvalidity).await?); let mut cache = self.mailboxes.lock().unwrap(); if let Some(concurrent_mb) = cache.get(&id).and_then(Weak::upgrade) { drop(mb); // we worked for nothing but at least we didn't starve someone else Ok(concurrent_mb) } else { cache.insert(id, Arc::downgrade(&mb)); Ok(mb) } } // ---- Mailbox list management ---- async fn load_mailbox_list(&self) -> Result<(MailboxList, Option)> { let (mut list, ct) = match self.k2v.read_item(MAILBOX_LIST_PK, MAILBOX_LIST_SK).await { Err(k2v_client::Error::NotFound) => (MailboxList::new(), None), Err(e) => return Err(e.into()), Ok(cv) => { let mut list = MailboxList::new(); for v in cv.value { if let K2vValue::Value(vbytes) = v { let list2 = open_deserialize::(&vbytes, &self.creds.keys.master)?; list.merge(list2); } } (list, Some(cv.causality)) } }; self.ensure_inbox_exists(&mut list, &ct).await?; Ok((list, ct)) } async fn ensure_inbox_exists( &self, list: &mut MailboxList, ct: &Option, ) -> Result { // If INBOX doesn't exist, create a new mailbox with that name // and save new mailbox list. // Also, ensure that the mpsc::watch that keeps track of the // inbox id is up-to-date. let saved; let (inbox_id, inbox_uidvalidity) = match list.create_mailbox(INBOX) { CreatedMailbox::Created(i, v) => { self.save_mailbox_list(list, ct.clone()).await?; saved = true; (i, v) } CreatedMailbox::Existed(i, v) => { saved = false; (i, v) } }; let inbox_id = Some((inbox_id, inbox_uidvalidity)); if *self.tx_inbox_id.borrow() != inbox_id { self.tx_inbox_id.send(inbox_id).unwrap(); } Ok(saved) } async fn save_mailbox_list( &self, list: &MailboxList, ct: Option, ) -> Result<()> { let list_blob = seal_serialize(list, &self.creds.keys.master)?; self.k2v .insert_item(MAILBOX_LIST_PK, MAILBOX_LIST_SK, list_blob, ct) .await?; Ok(()) } } // ---- User's mailbox list (serialized in K2V) ---- #[derive(Serialize, Deserialize)] struct MailboxList(BTreeMap); #[derive(Serialize, Deserialize, Clone, Copy, Debug)] struct MailboxListEntry { id_lww: (u64, Option), uidvalidity: ImapUidvalidity, } impl MailboxListEntry { fn merge(&mut self, other: &Self) { // Simple CRDT merge rule if other.id_lww.0 > self.id_lww.0 || (other.id_lww.0 == self.id_lww.0 && other.id_lww.1 > self.id_lww.1) { self.id_lww = other.id_lww; } self.uidvalidity = std::cmp::max(self.uidvalidity, other.uidvalidity); } } impl MailboxList { fn new() -> Self { Self(BTreeMap::new()) } fn merge(&mut self, list2: Self) { for (k, v) in list2.0.into_iter() { if let Some(e) = self.0.get_mut(&k) { e.merge(&v); } else { self.0.insert(k, v); } } } fn existing_mailbox_names(&self) -> Vec { self.0 .iter() .filter(|(_, v)| v.id_lww.1.is_some()) .map(|(k, _)| k.to_string()) .collect() } fn has_mailbox(&self, name: &str) -> bool { matches!( self.0.get(name), Some(MailboxListEntry { id_lww: (_, Some(_)), .. }) ) } fn get_mailbox(&self, name: &str) -> Option<(ImapUidvalidity, Option)> { self.0.get(name).map( |MailboxListEntry { id_lww: (_, mailbox_id), uidvalidity, }| (*uidvalidity, *mailbox_id), ) } /// Ensures mailbox `name` maps to id `id`. /// If it already mapped to that, returns None. /// If a change had to be done, returns Some(new uidvalidity in mailbox). fn set_mailbox(&mut self, name: &str, id: Option) -> Option { let (ts, id, uidvalidity) = match self.0.get_mut(name) { None => { if id.is_none() { return None; } else { (now_msec(), id, ImapUidvalidity::new(1).unwrap()) } } Some(MailboxListEntry { id_lww, uidvalidity, }) => { if id_lww.1 == id { return None; } else { ( std::cmp::max(id_lww.0 + 1, now_msec()), id, ImapUidvalidity::new(uidvalidity.get() + 1).unwrap(), ) } } }; self.0.insert( name.into(), MailboxListEntry { id_lww: (ts, id), uidvalidity, }, ); Some(uidvalidity) } fn update_uidvalidity(&mut self, name: &str, new_uidvalidity: ImapUidvalidity) { match self.0.get_mut(name) { None => { self.0.insert( name.into(), MailboxListEntry { id_lww: (now_msec(), None), uidvalidity: new_uidvalidity, }, ); } Some(MailboxListEntry { uidvalidity, .. }) => { *uidvalidity = std::cmp::max(*uidvalidity, new_uidvalidity); } } } fn create_mailbox(&mut self, name: &str) -> CreatedMailbox { if let Some(MailboxListEntry { id_lww: (_, Some(id)), uidvalidity, }) = self.0.get(name) { return CreatedMailbox::Existed(*id, *uidvalidity); } let id = gen_ident(); let uidvalidity = self.set_mailbox(name, Some(id)).unwrap(); CreatedMailbox::Created(id, uidvalidity) } fn rename_mailbox(&mut self, old_name: &str, new_name: &str) -> Result<()> { if let Some((uidvalidity, Some(mbid))) = self.get_mailbox(old_name) { if self.has_mailbox(new_name) { bail!( "Cannot rename {} into {}: {} already exists", old_name, new_name, new_name ); } self.set_mailbox(old_name, None); self.set_mailbox(new_name, Some(mbid)); self.update_uidvalidity(new_name, uidvalidity); Ok(()) } else { bail!( "Cannot rename {} into {}: {} doesn't exist", old_name, new_name, old_name ); } } } enum CreatedMailbox { Created(UniqueIdent, ImapUidvalidity), Existed(UniqueIdent, ImapUidvalidity), } // ---- User cache ---- lazy_static! { static ref USER_CACHE: std::sync::Mutex>> = std::sync::Mutex::new(HashMap::new()); }