aerogramme/src/mail/incoming.rs

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Rust
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use std::collections::HashMap;
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use std::convert::TryFrom;
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use std::sync::{Arc, Weak};
use std::time::Duration;
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use anyhow::{anyhow, bail, Result};
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use futures::{future::BoxFuture, FutureExt};
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use k2v_client::{CausalityToken, K2vClient, K2vValue};
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use rusoto_s3::{
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DeleteObjectRequest, GetObjectRequest, ListObjectsV2Request, PutObjectRequest, S3Client, S3,
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};
use tokio::io::AsyncReadExt;
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use tokio::sync::watch;
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use tracing::{error, info, warn};
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use crate::cryptoblob;
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use crate::k2v_util::k2v_wait_value_changed;
use crate::login::{Credentials, PublicCredentials};
use crate::mail::mailbox::Mailbox;
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use crate::mail::uidindex::ImapUidvalidity;
use crate::mail::unique_ident::*;
use crate::mail::user::User;
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use crate::mail::IMF;
use crate::time::now_msec;
const INCOMING_PK: &str = "incoming";
const INCOMING_LOCK_SK: &str = "lock";
const INCOMING_WATCH_SK: &str = "watch";
const MESSAGE_KEY: &str = "message-key";
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// When a lock is held, it is held for LOCK_DURATION (here 5 minutes)
// It is renewed every LOCK_DURATION/3
// If we are at 2*LOCK_DURATION/3 and haven't renewed, we assume we
// lost the lock.
const LOCK_DURATION: Duration = Duration::from_secs(300);
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// In addition to checking when notified, also check for new mail every 10 minutes
const MAIL_CHECK_INTERVAL: Duration = Duration::from_secs(600);
pub async fn incoming_mail_watch_process(
user: Weak<User>,
creds: Credentials,
rx_inbox_id: watch::Receiver<Option<(UniqueIdent, ImapUidvalidity)>>,
) {
if let Err(e) = incoming_mail_watch_process_internal(user, creds, rx_inbox_id).await {
error!("Error in incoming mail watch process: {}", e);
}
}
async fn incoming_mail_watch_process_internal(
user: Weak<User>,
creds: Credentials,
mut rx_inbox_id: watch::Receiver<Option<(UniqueIdent, ImapUidvalidity)>>,
) -> Result<()> {
let mut lock_held = k2v_lock_loop(creds.k2v_client()?, INCOMING_PK, INCOMING_LOCK_SK);
let k2v = creds.k2v_client()?;
let s3 = creds.s3_client()?;
let mut inbox: Option<Arc<Mailbox>> = None;
let mut prev_ct: Option<CausalityToken> = None;
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loop {
let new_mail = if *lock_held.borrow() {
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info!("incoming lock held");
let wait_new_mail = async {
loop {
match k2v_wait_value_changed(&k2v, &INCOMING_PK, &INCOMING_WATCH_SK, &prev_ct)
.await
{
Ok(cv) => break cv,
Err(e) => {
error!("Error in wait_new_mail: {}", e);
tokio::time::sleep(Duration::from_secs(30)).await;
}
}
}
};
tokio::select! {
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cv = wait_new_mail => Some(cv.causality),
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_ = tokio::time::sleep(MAIL_CHECK_INTERVAL) => prev_ct.clone(),
_ = lock_held.changed() => None,
_ = rx_inbox_id.changed() => None,
}
} else {
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info!("incoming lock not held");
tokio::select! {
_ = lock_held.changed() => None,
_ = rx_inbox_id.changed() => None,
}
};
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let user = match Weak::upgrade(&user) {
Some(user) => user,
None => {
info!("User no longer available, exiting incoming loop.");
break;
}
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};
info!("User still available");
// If INBOX no longer is same mailbox, open new mailbox
let inbox_id = rx_inbox_id.borrow().clone();
if let Some((id, uidvalidity)) = inbox_id {
if Some(id) != inbox.as_ref().map(|b| b.id) {
match user.open_mailbox_by_id(id, uidvalidity).await {
Ok(mb) => {
inbox = mb;
}
Err(e) => {
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inbox = None;
error!("Error when opening inbox ({}): {}", id, e);
tokio::time::sleep(Duration::from_secs(30)).await;
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continue;
}
}
}
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}
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// If we were able to open INBOX, and we have mail,
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// fetch new mail
if let (Some(inbox), Some(new_ct)) = (&inbox, new_mail) {
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match handle_incoming_mail(&user, &s3, inbox, &lock_held).await {
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Ok(()) => {
prev_ct = Some(new_ct);
}
Err(e) => {
error!("Could not fetch incoming mail: {}", e);
tokio::time::sleep(Duration::from_secs(30)).await;
}
}
}
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}
drop(rx_inbox_id);
Ok(())
}
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async fn handle_incoming_mail(
user: &Arc<User>,
s3: &S3Client,
inbox: &Arc<Mailbox>,
lock_held: &watch::Receiver<bool>,
) -> Result<()> {
let mut lor = ListObjectsV2Request::default();
lor.bucket = user.creds.storage.bucket.clone();
lor.max_keys = Some(1000);
lor.prefix = Some("incoming/".into());
let mails_res = s3.list_objects_v2(lor).await?;
for object in mails_res.contents.unwrap_or_default() {
if !*lock_held.borrow() {
break;
}
if let Some(key) = object.key {
if let Some(mail_id) = key.strip_prefix("incoming/") {
if let Ok(mail_id) = mail_id.parse::<UniqueIdent>() {
move_incoming_message(user, s3, inbox, mail_id).await?;
}
}
}
}
Ok(())
}
async fn move_incoming_message(
user: &Arc<User>,
s3: &S3Client,
inbox: &Arc<Mailbox>,
id: UniqueIdent,
) -> Result<()> {
info!("Moving incoming message: {}", id);
let object_key = format!("incoming/{}", id);
// 1. Fetch message from S3
let mut gor = GetObjectRequest::default();
gor.bucket = user.creds.storage.bucket.clone();
gor.key = object_key.clone();
let get_result = s3.get_object(gor).await?;
// 1.a decrypt message key from headers
info!("Object metadata: {:?}", get_result.metadata);
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let key_encrypted_b64 = get_result
.metadata
.as_ref()
.ok_or(anyhow!("Missing key in metadata"))?
.get(MESSAGE_KEY)
.ok_or(anyhow!("Missing key in metadata"))?;
let key_encrypted = base64::decode(key_encrypted_b64)?;
let message_key = sodiumoxide::crypto::sealedbox::open(
&key_encrypted,
&user.creds.keys.public,
&user.creds.keys.secret,
)
.map_err(|_| anyhow!("Cannot decrypt message key"))?;
let message_key =
cryptoblob::Key::from_slice(&message_key).ok_or(anyhow!("Invalid message key"))?;
// 1.b retrieve message body
let obj_body = get_result.body.ok_or(anyhow!("Missing object body"))?;
let mut mail_buf = Vec::with_capacity(get_result.content_length.unwrap_or(128) as usize);
obj_body
.into_async_read()
.read_to_end(&mut mail_buf)
.await?;
let plain_mail = cryptoblob::open(&mail_buf, &message_key)
.map_err(|_| anyhow!("Cannot decrypt email content"))?;
// 2 parse mail and add to inbox
let msg = IMF::try_from(&plain_mail[..]).map_err(|_| anyhow!("Invalid email body"))?;
inbox
.append_from_s3(msg, id, &object_key, message_key)
.await?;
// 3 delete from incoming
let mut dor = DeleteObjectRequest::default();
dor.bucket = user.creds.storage.bucket.clone();
dor.key = object_key.clone();
s3.delete_object(dor).await?;
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Ok(())
}
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// ---- UTIL: K2V locking loop, use this to try to grab a lock using a K2V entry as a signal ----
fn k2v_lock_loop(k2v: K2vClient, pk: &'static str, sk: &'static str) -> watch::Receiver<bool> {
let (held_tx, held_rx) = watch::channel(false);
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tokio::spawn(k2v_lock_loop_internal(k2v, pk, sk, held_tx));
held_rx
}
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#[derive(Clone, Debug)]
enum LockState {
Unknown,
Empty,
Held(UniqueIdent, u64, CausalityToken),
}
async fn k2v_lock_loop_internal(
k2v: K2vClient,
pk: &'static str,
sk: &'static str,
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held_tx: watch::Sender<bool>,
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) {
let (state_tx, mut state_rx) = watch::channel::<LockState>(LockState::Unknown);
let mut state_rx_2 = state_rx.clone();
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let our_pid = gen_ident();
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// Loop 1: watch state of lock in K2V, save that in corresponding watch channel
let watch_lock_loop: BoxFuture<Result<()>> = async {
let mut ct = None;
loop {
info!("k2v watch lock loop iter: ct = {:?}", ct);
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match k2v_wait_value_changed(&k2v, pk, sk, &ct).await {
Err(e) => {
error!(
"Error in k2v wait value changed: {} ; assuming we no longer hold lock.",
e
);
state_tx.send(LockState::Unknown)?;
tokio::time::sleep(Duration::from_secs(30)).await;
}
Ok(cv) => {
let mut lock_state = None;
for v in cv.value.iter() {
if let K2vValue::Value(vbytes) = v {
if vbytes.len() == 32 {
let ts = u64::from_be_bytes(vbytes[..8].try_into().unwrap());
let pid = UniqueIdent(vbytes[8..].try_into().unwrap());
if lock_state
.map(|(pid2, ts2)| ts > ts2 || (ts == ts2 && pid > pid2))
.unwrap_or(true)
{
lock_state = Some((pid, ts));
}
}
}
}
info!(
"k2v watch lock loop: changed, old ct = {:?}, new ct = {:?}, v = {:?}",
ct, cv.causality, lock_state
);
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state_tx.send(
lock_state
.map(|(pid, ts)| LockState::Held(pid, ts, cv.causality.clone()))
.unwrap_or(LockState::Empty),
)?;
ct = Some(cv.causality);
}
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}
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}
}
.boxed();
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// Loop 2: notify user whether we are holding the lock or not
let lock_notify_loop: BoxFuture<Result<()>> = async {
loop {
let now = now_msec();
let held_with_expiration_time = match &*state_rx.borrow_and_update() {
LockState::Held(pid, ts, _ct) if *pid == our_pid => {
let expiration_time = *ts - (LOCK_DURATION / 3).as_millis() as u64;
if now < expiration_time {
Some(expiration_time)
} else {
None
}
}
_ => None,
};
let held = held_with_expiration_time.is_some();
if held != *held_tx.borrow() {
held_tx.send(held)?;
}
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let await_expired = async {
match held_with_expiration_time {
None => futures::future::pending().await,
Some(expiration_time) => {
tokio::time::sleep(Duration::from_millis(expiration_time - now)).await
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}
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};
};
tokio::select!(
r = state_rx.changed() => {
r?;
}
_ = held_tx.closed() => bail!("held_tx closed, don't need to hold lock anymore"),
_ = await_expired => continue,
);
}
}
.boxed();
// Loop 3: acquire lock when relevant
let take_lock_loop: BoxFuture<Result<()>> = async {
loop {
let now = now_msec();
let state: LockState = state_rx_2.borrow_and_update().clone();
let (acquire_at, ct) = match state {
LockState::Unknown => {
// If state of the lock is unknown, don't try to acquire
state_rx_2.changed().await?;
continue;
}
LockState::Empty => (now, None),
LockState::Held(pid, ts, ct) => {
if pid == our_pid {
(ts - (2 * LOCK_DURATION / 3).as_millis() as u64, Some(ct))
} else {
(ts, Some(ct))
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}
}
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};
// Wait until it is time to acquire lock
if acquire_at > now {
tokio::select!(
r = state_rx_2.changed() => {
// If lock state changed in the meantime, don't acquire and loop around
r?;
continue;
}
_ = tokio::time::sleep(Duration::from_millis(acquire_at - now)) => ()
);
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}
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// Acquire lock
let mut lock = vec![0u8; 32];
lock[..8].copy_from_slice(&u64::to_be_bytes(
now_msec() + LOCK_DURATION.as_millis() as u64,
));
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lock[8..].copy_from_slice(&our_pid.0);
if let Err(e) = k2v.insert_item(pk, sk, lock, ct).await {
error!("Could not take lock: {}", e);
tokio::time::sleep(Duration::from_secs(30)).await;
}
// Wait for new information to loop back
state_rx_2.changed().await?;
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}
}
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.boxed();
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let _ = futures::try_join!(watch_lock_loop, lock_notify_loop, take_lock_loop);
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info!("lock loop exited, releasing");
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if !held_tx.is_closed() {
warn!("wierd...");
let _ = held_tx.send(false);
}
// If lock is ours, release it
let release = match &*state_rx.borrow() {
LockState::Held(pid, _, ct) if *pid == our_pid => Some(ct.clone()),
_ => None,
};
if let Some(ct) = release {
let _ = k2v.delete_item(pk, sk, ct.clone()).await;
}
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}
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// ---- LMTP SIDE: storing messages encrypted with user's pubkey ----
pub struct EncryptedMessage {
key: cryptoblob::Key,
encrypted_body: Vec<u8>,
}
impl EncryptedMessage {
pub fn new(body: Vec<u8>) -> Result<Self> {
let key = cryptoblob::gen_key();
let encrypted_body = cryptoblob::seal(&body, &key)?;
Ok(Self {
key,
encrypted_body,
})
}
pub async fn deliver_to(self: Arc<Self>, creds: PublicCredentials) -> Result<()> {
let s3_client = creds.storage.s3_client()?;
let k2v_client = creds.storage.k2v_client()?;
// Get causality token of previous watch key
let watch_ct = match k2v_client.read_item(INCOMING_PK, INCOMING_WATCH_SK).await {
Err(_) => None,
Ok(cv) => Some(cv.causality),
};
// Write mail to encrypted storage
let encrypted_key =
sodiumoxide::crypto::sealedbox::seal(self.key.as_ref(), &creds.public_key);
let key_header = base64::encode(&encrypted_key);
let mut por = PutObjectRequest::default();
por.bucket = creds.storage.bucket.clone();
por.key = format!("incoming/{}", gen_ident().to_string());
por.metadata = Some(
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[(MESSAGE_KEY.to_string(), key_header)]
.into_iter()
.collect::<HashMap<_, _>>(),
);
por.body = Some(self.encrypted_body.clone().into());
s3_client.put_object(por).await?;
// Update watch key to signal new mail
k2v_client
.insert_item(
INCOMING_PK,
INCOMING_WATCH_SK,
gen_ident().0.to_vec(),
watch_ct,
)
.await?;
Ok(())
}
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}