feat: Hide To header in encrypted messages

Author: link2xt

src/chat/chat_tests.rs

@@ -815,15 +815,6 @@ async fn test_self_talk() -> Result<()> {
     assert!(msg.get_showpadlock());
 
     let sent_msg = t.pop_sent_msg().await;
-    let payload = sent_msg.payload();
-    // Make sure the `To` field contains the address and not
-    // "undisclosed recipients".
-    // Otherwise Delta Chat core <1.153.0 assigns the message
-    // to the trash chat.
-    assert_eq!(
-        payload.match_indices("To: <[email protected]>\r\n").count(),
-        1
-    );
 
     let t2 = TestContext::new_alice().await;
     t2.recv_msg(&sent_msg).await;

src/mimefactory.rs

@@ -9,7 +9,7 @@ use data_encoding::BASE32_NOPAD;
 use deltachat_contact_tools::sanitize_bidi_characters;
 use iroh_gossip::proto::TopicId;
 use mail_builder::headers::HeaderType;
-use mail_builder::headers::address::{Address, EmailAddress};
+use mail_builder::headers::address::Address;
 use mail_builder::mime::MimePart;
 use tokio::fs;
 
@@ -1000,24 +1000,7 @@ impl MimeFactory {
             } else if header_name == "to" {
                 protected_headers.push(header.clone());
                 if is_encrypted {
-                    let mut to_without_names = to
-                        .clone()
-                        .into_iter()
-                        .filter_map(|header| match header {
-                            Address::Address(mb) => Some(Address::Address(EmailAddress {
-                                name: None,
-                                email: mb.email,
-                            })),
-                            _ => None,
-                        })
-                        .collect::<Vec<_>>();
-                    if to_without_names.is_empty() {
-                        to_without_names.push(hidden_recipients());
-                    }
-                    unprotected_headers.push((
-                        original_header_name,
-                        Address::new_list(to_without_names).into(),
-                    ));
+                    unprotected_headers.push(("To", hidden_recipients().into()));
                 } else {
                     unprotected_headers.push(header.clone());
                 }

src/mimefactory/mimefactory_tests.rs

@@ -750,8 +750,6 @@ async fn test_remove_member_bcc() -> Result<()> {
 
     let bob_id = alice.add_or_lookup_contact_id(bob).await;
     let charlie_id = alice.add_or_lookup_contact_id(charlie).await;
-    let charlie_contact = Contact::get_by_id(alice, charlie_id).await?;
-    let charlie_addr = charlie_contact.get_addr();
 
     let alice_chat_id = create_group(alice, "foo").await?;
     add_contact_to_chat(alice, alice_chat_id, bob_id).await?;
@@ -770,11 +768,11 @@ async fn test_remove_member_bcc() -> Result<()> {
     for to_addr in to.iter() {
         match to_addr {
             mailparse::MailAddr::Single(info) => {
-                // Addresses should be of existing members (Alice and Bob) and not Charlie.
-                assert_ne!(info.addr, charlie_addr);
+                panic!("Single addresses are not expected here: {info:?}");
             }
-            mailparse::MailAddr::Group(_) => {
-                panic!("Group addresses are not expected here");
+            mailparse::MailAddr::Group(info) => {
+                assert_eq!(info.group_name, "hidden-recipients");
+                assert_eq!(info.addrs, []);
             }
         }
     }

src/receive_imf.rs

@@ -2575,7 +2575,7 @@ async fn is_probably_private_reply(
     // should be assigned to the group chat. We restrict this exception to classical emails, as chat-group-messages
     // contain a Chat-Group-Id header and can be sorted into the correct chat this way.
 
-    if mime_parser.recipients.len() != 1 {
+    if mime_parser.recipients.len() > 1 {
         return Ok(false);
     }
 

src/receive_imf/receive_imf_tests.rs

@@ -4849,14 +4849,15 @@ async fn test_prefer_references_to_downloaded_msgs() -> Result<()> {
     let received = bob.recv_msg(&sent).await;
     assert_eq!(received.download_state, DownloadState::Available);
     assert_ne!(received.chat_id, bob_chat_id);
-    assert_eq!(received.chat_id, bob.get_chat(alice).await.id);
+    let bob_alice_chat_id = bob.get_chat(alice).await.id;
+    assert_eq!(received.chat_id, bob_alice_chat_id);
 
     let mut msg = Message::new(Viewtype::File);
     msg.set_file_from_bytes(alice, "file", file_bytes, None)?;
     let sent = alice.send_msg(alice_chat_id, &mut msg).await;
     let received = bob.recv_msg(&sent).await;
     assert_eq!(received.download_state, DownloadState::Available);
-    assert_eq!(received.chat_id, bob_chat_id);
+    assert_eq!(received.chat_id, bob_alice_chat_id);
 
     Ok(())
 }