From 05eb2e050beaf9e23e586f1d185e89ddc0d49adb Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Fri, 1 Jul 2022 20:09:26 +0200
Subject: Code to add mail to inbox

---
 src/mail/incoming.rs | 96 ++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 89 insertions(+), 7 deletions(-)

(limited to 'src/mail/incoming.rs')

diff --git a/src/mail/incoming.rs b/src/mail/incoming.rs
index d87456f..86cbc07 100644
--- a/src/mail/incoming.rs
+++ b/src/mail/incoming.rs
@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::convert::TryFrom;
 use std::pin::Pin;
 use std::sync::{Arc, Weak};
 use std::time::Duration;
@@ -6,7 +7,10 @@ use std::time::Duration;
 use anyhow::{anyhow, bail, Result};
 use futures::{future::BoxFuture, Future, FutureExt};
 use k2v_client::{CausalValue, CausalityToken, K2vClient, K2vValue};
-use rusoto_s3::{PutObjectRequest, S3Client, S3};
+use rusoto_s3::{
+    GetObjectRequest, HeadObjectRequest, ListObjectsV2Request, PutObjectRequest, S3Client, S3,
+};
+use tokio::io::AsyncReadExt;
 use tokio::sync::watch;
 use tracing::{error, info, warn};
 
@@ -16,12 +20,15 @@ use crate::mail::mailbox::Mailbox;
 use crate::mail::uidindex::ImapUidvalidity;
 use crate::mail::unique_ident::*;
 use crate::mail::user::User;
+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";
+
 // 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
@@ -113,10 +120,10 @@ async fn incoming_mail_watch_process_internal(
             }
         }
 
-        // If we were able to open INBOX, and we have mail (implies lock is held),
+        // If we were able to open INBOX, and we have mail,
         // fetch new mail
         if let (Some(inbox), Some(new_ct)) = (&inbox, new_mail) {
-            match handle_incoming_mail(&user, &s3, inbox).await {
+            match handle_incoming_mail(&user, &s3, inbox, &lock_held).await {
                 Ok(()) => {
                     prev_ct = Some(new_ct);
                 }
@@ -131,8 +138,84 @@ async fn incoming_mail_watch_process_internal(
     Ok(())
 }
 
-async fn handle_incoming_mail(user: &Arc<User>, s3: &S3Client, inbox: &Arc<Mailbox>) -> Result<()> {
-    unimplemented!()
+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
+    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?;
+
+    Ok(())
 }
 
 // ---- UTIL: K2V locking loop, use this to try to grab a lock using a K2V entry as a signal ----
@@ -307,7 +390,6 @@ async fn k2v_lock_loop_internal(
     if let Some(ct) = release {
         let _ = k2v.delete_item(pk, sk, ct.clone()).await;
     }
-
 }
 
 // ---- UTIL: function to wait for a value to have changed in K2V ----
@@ -372,7 +454,7 @@ impl EncryptedMessage {
         por.bucket = creds.storage.bucket.clone();
         por.key = format!("incoming/{}", gen_ident().to_string());
         por.metadata = Some(
-            [("Message-Key".to_string(), key_header)]
+            [(MESSAGE_KEY.to_string(), key_header)]
                 .into_iter()
                 .collect::<HashMap<_, _>>(),
         );
-- 
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