Implement reactions

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 ### API-Changes
+- added reactions support #3644
 
 ### Changes
 - simplify `UPSERT` queries #3676

deltachat-ffi/deltachat.h

@@ -11,16 +11,17 @@ extern "C" {
 #endif
 
 
-typedef struct _dc_context  dc_context_t;
+typedef struct _dc_context   dc_context_t;
-typedef struct _dc_accounts dc_accounts_t;
+typedef struct _dc_accounts  dc_accounts_t;
-typedef struct _dc_array    dc_array_t;
+typedef struct _dc_array     dc_array_t;
-typedef struct _dc_chatlist dc_chatlist_t;
+typedef struct _dc_chatlist  dc_chatlist_t;
-typedef struct _dc_chat     dc_chat_t;
+typedef struct _dc_chat      dc_chat_t;
-typedef struct _dc_msg      dc_msg_t;
+typedef struct _dc_msg       dc_msg_t;
-typedef struct _dc_contact  dc_contact_t;
+typedef struct _dc_reactions dc_reactions_t;
-typedef struct _dc_lot      dc_lot_t;
+typedef struct _dc_contact   dc_contact_t;
-typedef struct _dc_provider dc_provider_t;
+typedef struct _dc_lot       dc_lot_t;
-typedef struct _dc_event    dc_event_t;
+typedef struct _dc_provider  dc_provider_t;
+typedef struct _dc_event     dc_event_t;
 typedef struct _dc_event_emitter dc_event_emitter_t;
 typedef struct _dc_jsonrpc_instance dc_jsonrpc_instance_t;
 
@@ -991,6 +992,34 @@ uint32_t        dc_send_text_msg             (dc_context_t* context, uint32_t ch
 uint32_t dc_send_videochat_invitation (dc_context_t* context, uint32_t chat_id);
 
 
+/**
+ * Send a reaction to message.
+ *
+ * Reaction is a string of emojis separated by spaces. Reaction to a
+ * single message can be sent multiple times. The last reaction
+ * received overrides all previously received reactions. It is
+ * possible to remove all reactions by sending an empty string.
+ *
+ * @memberof dc_context_t
+ * @param context The context object.
+ * @param msg_id ID of the message you react to.
+ * @param reaction A string consisting of emojis separated by spaces.
+ * @return The ID of the message sent out or 0 for errors.
+ */
+uint32_t dc_send_reaction (dc_context_t* context, uint32_t msg_id, char *reaction);
+
+
+/**
+ * Get a structure with reactions to the message.
+ *
+ * @memberof dc_context_t
+ * @param context The context object.
+ * @param msg_id The message ID to get reactions for.
+ * @return A structure with all reactions to the message.
+ */
+dc_reactions_t* dc_get_msg_reactions (dc_context_t *context, int msg_id);
+
+
 /**
  * A webxdc instance sends a status update to its other members.
  *
@@ -4882,7 +4911,49 @@ uint32_t        dc_lot_get_id            (const dc_lot_t* lot);
  * @param lot The lot object.
  * @return The timestamp as defined by the creator of the object. 0 if there is not timestamp or on errors.
  */
-int64_t          dc_lot_get_timestamp     (const dc_lot_t* lot);
+int64_t         dc_lot_get_timestamp     (const dc_lot_t* lot);
+
+
+/**
+ * @class dc_reactions_t
+ *
+ * An object representing all reactions for a single message.
+ */
+
+/**
+ * Returns array of contacts which reacted to the given message.
+ *
+ * @memberof dc_reactions_t
+ * @param reactions The object containing message reactions.
+ * @return array of contact IDs. Use dc_array_get_cnt() to get array length and
+ *         dc_array_get_id() to get the IDs. Should be freed using `dc_array_unref()` after usage.
+ */
+dc_array_t*     dc_reactions_get_contacts(dc_reactions_t* reactions);
+
+
+/**
+ * Returns a string containing space-separated reactions of a single contact.
+ *
+ * @memberof dc_reactions_t
+ * @param reactions The object containing message reactions.
+ * @param contact_id ID of the contact.
+ * @return Space-separated list of emoji sequences, which could be empty.
+ *         Returned string should not be modified and should be freed
+ *         with dc_str_unref() after usage.
+ */
+char*           dc_reactions_get_by_contact_id(dc_reactions_t* reactions, uint32_t contact_id);
+
+
+/**
+ * Frees an object containing message reactions.
+ *
+ * Reactions objects are created by dc_get_msg_reactions().
+ *
+ * @memberof dc_reactions_t
+ * @param reactions The object to free.
+ *     If NULL is given, nothing is done.
+ */
+void            dc_reactions_unref       (dc_reactions_t* reactions);
 
 
 /**
@@ -5533,6 +5604,15 @@ void dc_event_unref(dc_event_t* event);
 #define DC_EVENT_MSGS_CHANGED             2000
 
 
+/**
+ * Message reactions changed.
+ *
+ * @param data1 (int) chat_id ID of the chat affected by the changes.
+ * @param data2 (int) msg_id ID of the message for which reactions were changed.
+ */
+#define DC_EVENT_REACTIONS_CHANGED        2001
+
+
 /**
  * There is a fresh message. Typically, the user will show an notification
  * when receiving this message.

deltachat-ffi/src/dc_array.rs

@@ -1,5 +1,6 @@
 use crate::chat::ChatItem;
 use crate::constants::DC_MSG_ID_DAYMARKER;
+use crate::contact::ContactId;
 use crate::location::Location;
 use crate::message::MsgId;
 
@@ -7,6 +8,7 @@ use crate::message::MsgId;
 #[derive(Debug, Clone)]
 pub enum dc_array_t {
     MsgIds(Vec<MsgId>),
+    ContactIds(Vec<ContactId>),
     Chat(Vec<ChatItem>),
     Locations(Vec<Location>),
     Uint(Vec<u32>),
@@ -16,6 +18,7 @@ impl dc_array_t {
     pub(crate) fn get_id(&self, index: usize) -> u32 {
         match self {
             Self::MsgIds(array) => array[index].to_u32(),
+            Self::ContactIds(array) => array[index].to_u32(),
             Self::Chat(array) => match array[index] {
                 ChatItem::Message { msg_id } => msg_id.to_u32(),
                 ChatItem::DayMarker { .. } => DC_MSG_ID_DAYMARKER,
@@ -28,6 +31,7 @@ impl dc_array_t {
     pub(crate) fn get_timestamp(&self, index: usize) -> Option<i64> {
         match self {
             Self::MsgIds(_) => None,
+            Self::ContactIds(_) => None,
             Self::Chat(array) => array.get(index).and_then(|item| match item {
                 ChatItem::Message { .. } => None,
                 ChatItem::DayMarker { timestamp } => Some(*timestamp),
@@ -40,6 +44,7 @@ impl dc_array_t {
     pub(crate) fn get_marker(&self, index: usize) -> Option<&str> {
         match self {
             Self::MsgIds(_) => None,
+            Self::ContactIds(_) => None,
             Self::Chat(_) => None,
             Self::Locations(array) => array
                 .get(index)
@@ -60,6 +65,7 @@ impl dc_array_t {
     pub(crate) fn len(&self) -> usize {
         match self {
             Self::MsgIds(array) => array.len(),
+            Self::ContactIds(array) => array.len(),
             Self::Chat(array) => array.len(),
             Self::Locations(array) => array.len(),
             Self::Uint(array) => array.len(),
@@ -83,6 +89,12 @@ impl From<Vec<MsgId>> for dc_array_t {
     }
 }
 
+impl From<Vec<ContactId>> for dc_array_t {
+    fn from(array: Vec<ContactId>) -> Self {
+        dc_array_t::ContactIds(array)
+    }
+}
+
 impl From<Vec<ChatItem>> for dc_array_t {
     fn from(array: Vec<ChatItem>) -> Self {
         dc_array_t::Chat(array)

deltachat-ffi/src/lib.rs

@@ -37,6 +37,7 @@ use deltachat::context::Context;
 use deltachat::ephemeral::Timer as EphemeralTimer;
 use deltachat::key::DcKey;
 use deltachat::message::MsgId;
+use deltachat::reaction::{get_msg_reactions, send_reaction, Reactions};
 use deltachat::stock_str::StockMessage;
 use deltachat::stock_str::StockStrings;
 use deltachat::webxdc::StatusUpdateSerial;
@@ -66,6 +67,8 @@ use deltachat::chatlist::Chatlist;
 /// Struct representing the deltachat context.
 pub type dc_context_t = Context;
 
+pub type dc_reactions_t = Reactions;
+
 static RT: Lazy<Runtime> = Lazy::new(|| Runtime::new().expect("unable to create tokio runtime"));
 
 fn block_on<T>(fut: T) -> T::Output
@@ -498,6 +501,7 @@ pub unsafe extern "C" fn dc_event_get_id(event: *mut dc_event_t) -> libc::c_int
         EventType::Error(_) => 400,
         EventType::ErrorSelfNotInGroup(_) => 410,
         EventType::MsgsChanged { .. } => 2000,
+        EventType::ReactionsChanged { .. } => 2001,
         EventType::IncomingMsg { .. } => 2005,
         EventType::MsgsNoticed { .. } => 2008,
         EventType::MsgDelivered { .. } => 2010,
@@ -542,6 +546,7 @@ pub unsafe extern "C" fn dc_event_get_data1_int(event: *mut dc_event_t) -> libc:
         | EventType::SelfavatarChanged
         | EventType::ErrorSelfNotInGroup(_) => 0,
         EventType::MsgsChanged { chat_id, .. }
+        | EventType::ReactionsChanged { chat_id, .. }
         | EventType::IncomingMsg { chat_id, .. }
         | EventType::MsgsNoticed(chat_id)
         | EventType::MsgDelivered { chat_id, .. }
@@ -598,6 +603,7 @@ pub unsafe extern "C" fn dc_event_get_data2_int(event: *mut dc_event_t) -> libc:
         | EventType::SelfavatarChanged => 0,
         EventType::ChatModified(_) => 0,
         EventType::MsgsChanged { msg_id, .. }
+        | EventType::ReactionsChanged { msg_id, .. }
         | EventType::IncomingMsg { msg_id, .. }
         | EventType::MsgDelivered { msg_id, .. }
         | EventType::MsgFailed { msg_id, .. }
@@ -637,6 +643,7 @@ pub unsafe extern "C" fn dc_event_get_data2_str(event: *mut dc_event_t) -> *mut
             data2.into_raw()
         }
         EventType::MsgsChanged { .. }
+        | EventType::ReactionsChanged { .. }
         | EventType::IncomingMsg { .. }
         | EventType::MsgsNoticed(_)
         | EventType::MsgDelivered { .. }
@@ -948,6 +955,48 @@ pub unsafe extern "C" fn dc_send_videochat_invitation(
     })
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_send_reaction(
+    context: *mut dc_context_t,
+    msg_id: u32,
+    reaction: *const libc::c_char,
+) -> u32 {
+    if context.is_null() {
+        eprintln!("ignoring careless call to dc_send_reaction()");
+        return 0;
+    }
+    let ctx = &*context;
+
+    block_on(async move {
+        send_reaction(ctx, MsgId::new(msg_id), &to_string_lossy(reaction))
+            .await
+            .map(|msg_id| msg_id.to_u32())
+            .unwrap_or_log_default(ctx, "Failed to send reaction")
+    })
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dc_get_msg_reactions(
+    context: *mut dc_context_t,
+    msg_id: u32,
+) -> *mut dc_reactions_t {
+    if context.is_null() {
+        eprintln!("ignoring careless call to dc_get_msg_reactions()");
+        return ptr::null_mut();
+    }
+    let ctx = &*context;
+
+    let reactions = if let Ok(reactions) = block_on(get_msg_reactions(ctx, MsgId::new(msg_id)))
+        .log_err(ctx, "failed dc_get_msg_reactions() call")
+    {
+        reactions
+    } else {
+        return ptr::null_mut();
+    };
+
+    Box::into_raw(Box::new(reactions))
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_send_webxdc_status_update(
     context: *mut dc_context_t,
@@ -3988,6 +4037,45 @@ pub unsafe extern "C" fn dc_lot_get_timestamp(lot: *mut dc_lot_t) -> i64 {
     lot.get_timestamp()
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_reactions_get_contacts(
+    reactions: *mut dc_reactions_t,
+) -> *mut dc_array::dc_array_t {
+    if reactions.is_null() {
+        eprintln!("ignoring careless call to dc_reactions_get_contacts()");
+        return ptr::null_mut();
+    }
+
+    let reactions = &*reactions;
+    let array: dc_array_t = reactions.contacts().into();
+
+    Box::into_raw(Box::new(array))
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dc_reactions_get_by_contact_id(
+    reactions: *mut dc_reactions_t,
+    contact_id: u32,
+) -> *mut libc::c_char {
+    if reactions.is_null() {
+        eprintln!("ignoring careless call to dc_reactions_get_by_contact_id()");
+        return ptr::null_mut();
+    }
+
+    let reactions = &*reactions;
+    reactions.get(ContactId::new(contact_id)).as_str().strdup()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn dc_reactions_unref(reactions: *mut dc_reactions_t) {
+    if reactions.is_null() {
+        eprintln!("ignoring careless call to dc_reactions_unref()");
+        return;
+    }
+
+    drop(Box::from_raw(reactions));
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_str_unref(s: *mut libc::c_char) {
     libc::free(s as *mut _)

deltachat-jsonrpc/src/api/events.rs

@@ -102,6 +102,14 @@ pub enum JSONRPCEventType {
         msg_id: u32,
     },
 
+    /// Reactions for the message changed.
+    #[serde(rename_all = "camelCase")]
+    ReactionsChanged {
+        chat_id: u32,
+        msg_id: u32,
+        contact_id: u32,
+    },
+
     /// There is a fresh message. Typically, the user will show an notification
     /// when receiving this message.
     ///
@@ -284,6 +292,15 @@ impl From<EventType> for JSONRPCEventType {
                 chat_id: chat_id.to_u32(),
                 msg_id: msg_id.to_u32(),
             },
+            EventType::ReactionsChanged {
+                chat_id,
+                msg_id,
+                contact_id,
+            } => ReactionsChanged {
+                chat_id: chat_id.to_u32(),
+                msg_id: msg_id.to_u32(),
+                contact_id: contact_id.to_u32(),
+            },
             EventType::IncomingMsg { chat_id, msg_id } => IncomingMsg {
                 chat_id: chat_id.to_u32(),
                 msg_id: msg_id.to_u32(),

deltachat-jsonrpc/src/api/types/message.rs

@@ -205,6 +205,9 @@ pub enum MessageViewtype {
     /// Text message.
     Text,
 
+    /// Reaction emoji.
+    Reaction,
+
     /// Image message.
     /// If the image is an animated GIF, the type `Viewtype.Gif` should be used.
     Image,
@@ -242,6 +245,7 @@ impl From<Viewtype> for MessageViewtype {
         match viewtype {
             Viewtype::Unknown => MessageViewtype::Unknown,
             Viewtype::Text => MessageViewtype::Text,
+            Viewtype::Reaction => MessageViewtype::Reaction,
             Viewtype::Image => MessageViewtype::Image,
             Viewtype::Gif => MessageViewtype::Gif,
             Viewtype::Sticker => MessageViewtype::Sticker,
@@ -260,6 +264,7 @@ impl From<MessageViewtype> for Viewtype {
         match viewtype {
             MessageViewtype::Unknown => Viewtype::Unknown,
             MessageViewtype::Text => Viewtype::Text,
+            MessageViewtype::Reaction => Viewtype::Reaction,
             MessageViewtype::Image => Viewtype::Image,
             MessageViewtype::Gif => Viewtype::Gif,
             MessageViewtype::Sticker => Viewtype::Sticker,

examples/repl/cmdline.rs

@@ -20,6 +20,7 @@ use deltachat::log::LogExt;
 use deltachat::message::{self, Message, MessageState, MsgId, Viewtype};
 use deltachat::peerstate::*;
 use deltachat::qr::*;
+use deltachat::reaction::send_reaction;
 use deltachat::receive_imf::*;
 use deltachat::sql;
 use deltachat::tools::*;
@@ -407,6 +408,7 @@ pub async fn cmdline(context: Context, line: &str, chat_id: &mut ChatId) -> Resu
                  resend <msg-id>\n\
                  markseen <msg-id>\n\
                  delmsg <msg-id>\n\
+                 react <msg-id> [<reaction>]\n\
                  ===========================Contact commands==\n\
                  listcontacts [<query>]\n\
                  listverified [<query>]\n\
@@ -1121,6 +1123,12 @@ pub async fn cmdline(context: Context, line: &str, chat_id: &mut ChatId) -> Resu
             ids[0] = MsgId::new(arg1.parse()?);
             message::delete_msgs(&context, &ids).await?;
         }
+        "react" => {
+            ensure!(!arg1.is_empty(), "Argument <msg-id> missing.");
+            let msg_id = MsgId::new(arg1.parse()?);
+            let reaction = arg2;
+            send_reaction(&context, msg_id, reaction).await?;
+        }
         "listcontacts" | "contacts" | "listverified" => {
             let contacts = Contact::get_all(
                 &context,

examples/repl/main.rs

@@ -72,6 +72,19 @@ fn receive_event(event: EventType) {
                 ))
             );
         }
+        EventType::ReactionsChanged {
+            chat_id,
+            msg_id,
+            contact_id,
+        } => {
+            info!(
+                "{}",
+                yellow.paint(format!(
+                    "Received REACTIONS_CHANGED(chat_id={}, msg_id={}, contact_id={})",
+                    chat_id, msg_id, contact_id
+                ))
+            );
+        }
         EventType::ContactsChanged(_) => {
             info!("{}", yellow.paint("Received CONTACTS_CHANGED()"));
         }
@@ -208,7 +221,7 @@ const CHAT_COMMANDS: [&str; 36] = [
     "accept",
     "blockchat",
 ];
-const MESSAGE_COMMANDS: [&str; 8] = [
+const MESSAGE_COMMANDS: [&str; 9] = [
     "listmsgs",
     "msginfo",
     "listfresh",
@@ -217,6 +230,7 @@ const MESSAGE_COMMANDS: [&str; 8] = [
     "markseen",
     "delmsg",
     "download",
+    "react",
 ];
 const CONTACT_COMMANDS: [&str; 9] = [
     "listcontacts",

node/constants.js

@@ -50,6 +50,7 @@ module.exports = {
   DC_EVENT_MSG_FAILED: 2012,
   DC_EVENT_MSG_READ: 2015,
   DC_EVENT_NEW_BLOB_FILE: 150,
+  DC_EVENT_REACTIONS_CHANGED: 2001,
   DC_EVENT_SECUREJOIN_INVITER_PROGRESS: 2060,
   DC_EVENT_SECUREJOIN_JOINER_PROGRESS: 2061,
   DC_EVENT_SELFAVATAR_CHANGED: 2110,

node/events.js

@@ -14,6 +14,7 @@ module.exports = {
   400: 'DC_EVENT_ERROR',
   410: 'DC_EVENT_ERROR_SELF_NOT_IN_GROUP',
   2000: 'DC_EVENT_MSGS_CHANGED',
+  2001: 'DC_EVENT_REACTIONS_CHANGED',
   2005: 'DC_EVENT_INCOMING_MSG',
   2008: 'DC_EVENT_MSGS_NOTICED',
   2010: 'DC_EVENT_MSG_DELIVERED',

node/lib/constants.ts

@@ -50,6 +50,7 @@ export enum C {
   DC_EVENT_MSG_FAILED = 2012,
   DC_EVENT_MSG_READ = 2015,
   DC_EVENT_NEW_BLOB_FILE = 150,
+  DC_EVENT_REACTIONS_CHANGED = 2001,
   DC_EVENT_SECUREJOIN_INVITER_PROGRESS = 2060,
   DC_EVENT_SECUREJOIN_JOINER_PROGRESS = 2061,
   DC_EVENT_SELFAVATAR_CHANGED = 2110,
@@ -282,6 +283,7 @@ export const EventId2EventName: { [key: number]: string } = {
   400: 'DC_EVENT_ERROR',
   410: 'DC_EVENT_ERROR_SELF_NOT_IN_GROUP',
   2000: 'DC_EVENT_MSGS_CHANGED',
+  2001: 'DC_EVENT_REACTIONS_CHANGED',
   2005: 'DC_EVENT_INCOMING_MSG',
   2008: 'DC_EVENT_MSGS_NOTICED',
   2010: 'DC_EVENT_MSG_DELIVERED',

src/chat.rs

@@ -1812,7 +1812,10 @@ pub async fn prepare_msg(context: &Context, chat_id: ChatId, msg: &mut Message)
 }
 
 async fn prepare_msg_blob(context: &Context, msg: &mut Message) -> Result<()> {
-    if msg.viewtype == Viewtype::Text || msg.viewtype == Viewtype::VideochatInvitation {
+    if msg.viewtype == Viewtype::Text
+        || msg.viewtype == Viewtype::VideochatInvitation
+        || msg.viewtype == Viewtype::Reaction
+    {
         // the caller should check if the message text is empty
     } else if msg.viewtype.has_file() {
         let blob = msg

src/contact.rs

@@ -34,7 +34,9 @@ const SEEN_RECENTLY_SECONDS: i64 = 600;
 ///
 /// Some contact IDs are reserved to identify special contacts.  This
 /// type can represent both the special as well as normal contacts.
-#[derive(Debug, Copy, Clone, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[derive(
+    Debug, Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize,
+)]
 pub struct ContactId(u32);
 
 impl ContactId {

src/events.rs

@@ -173,6 +173,13 @@ pub enum EventType {
         msg_id: MsgId,
     },
 
+    /// Reactions for the message changed.
+    ReactionsChanged {
+        chat_id: ChatId,
+        msg_id: MsgId,
+        contact_id: ContactId,
+    },
+
     /// There is a fresh message. Typically, the user will show an notification
     /// when receiving this message.
     ///

src/lib.rs

@@ -103,6 +103,7 @@ pub mod receive_imf;
 pub mod tools;
 
 pub mod accounts;
+pub mod reaction;
 
 /// if set imap/incoming and smtp/outgoing MIME messages will be printed
 pub const DCC_MIME_DEBUG: &str = "DCC_MIME_DEBUG";

src/message.rs

@@ -22,6 +22,7 @@ use crate::imap::markseen_on_imap_table;
 use crate::mimeparser::{parse_message_id, DeliveryReport, SystemMessage};
 use crate::param::{Param, Params};
 use crate::pgp::split_armored_data;
+use crate::reaction::get_msg_reactions;
 use crate::scheduler::InterruptInfo;
 use crate::sql;
 use crate::stock_str;
@@ -1082,6 +1083,11 @@ pub async fn get_msg_info(context: &Context, msg_id: MsgId) -> Result<String> {
 
     ret += "\n";
 
+    let reactions = get_msg_reactions(context, msg_id).await?;
+    if !reactions.is_empty() {
+        ret += &format!("Reactions: {}\n", reactions);
+    }
+
     if let Some(error) = msg.error.as_ref() {
         ret += &format!("Error: {}", error);
     }
@@ -1762,6 +1768,9 @@ pub enum Viewtype {
     /// The text of the message is set using dc_msg_set_text() and retrieved with dc_msg_get_text().
     Text = 10,
 
+    /// RFC 9078 reaction.
+    Reaction = 11,
+
     /// Image message.
     /// If the image is an animated GIF, the type DC_MSG_GIF should be used.
     /// File, width and height are set via dc_msg_set_file(), dc_msg_set_dimension
@@ -1821,6 +1830,7 @@ impl Viewtype {
         match self {
             Viewtype::Unknown => false,
             Viewtype::Text => false,
+            Viewtype::Reaction => false,
             Viewtype::Image => true,
             Viewtype::Gif => true,
             Viewtype::Sticker => true,

src/mimefactory.rs

@@ -1122,6 +1122,11 @@ impl<'a> MimeFactory<'a> {
                 "text/plain; charset=utf-8; format=flowed; delsp=no".to_string(),
             ))
             .body(message_text);
+
+        if self.msg.viewtype == Viewtype::Reaction {
+            main_part = main_part.header(("Content-Disposition", "reaction"));
+        }
+
         let mut parts = Vec::new();
 
         // add HTML-part, this is needed only if a HTML-message from a non-delta-client is forwarded;

src/mimeparser.rs

@@ -465,7 +465,10 @@ impl MimeMessage {
                     | Viewtype::Video
                     | Viewtype::File
                     | Viewtype::Webxdc => true,
-                    Viewtype::Unknown | Viewtype::Text | Viewtype::VideochatInvitation => false,
+                    Viewtype::Unknown
+                    | Viewtype::Text
+                    | Viewtype::Reaction
+                    | Viewtype::VideochatInvitation => false,
                 };
 
             if need_drop {
@@ -551,7 +554,10 @@ impl MimeMessage {
             }
 
             if prepend_subject && !subject.is_empty() {
-                let part_with_text = self.parts.iter_mut().find(|part| !part.msg.is_empty());
+                let part_with_text = self
+                    .parts
+                    .iter_mut()
+                    .find(|part| !part.msg.is_empty() && part.typ != Viewtype::Reaction);
                 if let Some(mut part) = part_with_text {
                     part.msg = format!("{} – {}", subject, part.msg);
                 }
@@ -913,6 +919,7 @@ impl MimeMessage {
         Ok(any_part_added)
     }
 
+    /// Returns true if any part was added, false otherwise.
     async fn add_single_part_if_known(
         &mut self,
         context: &Context,
@@ -946,6 +953,26 @@ impl MimeMessage {
                         warn!(context, "Missing attachment");
                         return Ok(false);
                     }
+                    mime::TEXT if msg_type == Viewtype::Reaction => {
+                        // Reaction.
+                        let decoded_data = match mail.get_body() {
+                            Ok(decoded_data) => decoded_data,
+                            Err(err) => {
+                                warn!(context, "Invalid body parsed {:?}", err);
+                                // Note that it's not always an error - might be no data
+                                return Ok(false);
+                            }
+                        };
+
+                        let part = Part {
+                            typ: Viewtype::Reaction,
+                            mimetype: Some(mime_type),
+                            msg: decoded_data,
+                            ..Default::default()
+                        };
+                        self.do_add_single_part(part);
+                        return Ok(true);
+                    }
                     mime::TEXT | mime::HTML => {
                         let decoded_data = match mail.get_body() {
                             Ok(decoded_data) => decoded_data,
@@ -1652,7 +1679,11 @@ fn get_mime_type(mail: &mailparse::ParsedMail<'_>) -> Result<(Mime, Viewtype)> {
 
     let viewtype = match mimetype.type_() {
         mime::TEXT => {
-            if !is_attachment_disposition(mail) {
+            if mail.get_content_disposition().disposition
+                == DispositionType::Extension("reaction".to_string())
+            {
+                Viewtype::Reaction
+            } else if !is_attachment_disposition(mail) {
                 match mimetype.subtype() {
                     mime::PLAIN | mime::HTML => Viewtype::Text,
                     _ => Viewtype::File,
@@ -3329,4 +3360,39 @@ Message.
 
         Ok(())
     }
+
+    /// Tests parsing of MIME message containing RFC 9078 reaction.
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_parse_reaction() -> Result<()> {
+        let alice = TestContext::new_alice().await;
+
+        let mime_message = MimeMessage::from_bytes(
+            &alice,
+            "To: alice@example.org\n\
+From: bob@example.net\n\
+Date: Today, 29 February 2021 00:00:10 -800\n\
+Message-ID: 56789@example.net\n\
+In-Reply-To: 12345@example.org\n\
+Subject: Meeting\n\
+Mime-Version: 1.0 (1.0)\n\
+Content-Type: text/plain; charset=utf-8\n\
+Content-Disposition: reaction\n\
+\n\
+\u{1F44D}"
+                .as_bytes(),
+        )
+        .await?;
+
+        assert_eq!(mime_message.parts.len(), 1);
+        assert_eq!(mime_message.parts[0].typ, Viewtype::Reaction);
+        assert_eq!(
+            mime_message
+                .get_header(HeaderDef::InReplyTo)
+                .and_then(|msgid| parse_message_id(msgid).ok())
+                .unwrap(),
+            "12345@example.org"
+        );
+
+        Ok(())
+    }
 }

src/reaction.rs

@@ -0,0 +1,428 @@
+//! # Reactions.
+//!
+//! Reactions are short messages consisting of emojis sent in reply to
+//! messages. Unlike normal messages which are added to the end of the chat,
+//! reactions are supposed to be displayed near the original messages.
+//!
+//! RFC 9078 specifies how reactions are transmitted in MIME messages.
+//!
+//! Reaction update semantics is not well-defined in RFC 9078, so
+//! Delta Chat uses the same semantics as in
+//! [XEP-0444](https://xmpp.org/extensions/xep-0444.html) section
+//! "3.2 Updating reactions to a message". Received reactions override
+//! all previously received reactions from the same user and it is
+//! possible to remove all reactions by sending an empty string as a reaction,
+//! even though RFC 9078 requires at least one emoji to be sent.
+
+use std::collections::BTreeMap;
+use std::fmt;
+
+use anyhow::Result;
+
+use crate::chat::{send_msg, ChatId};
+use crate::contact::ContactId;
+use crate::context::Context;
+use crate::events::EventType;
+use crate::message::{rfc724_mid_exists, Message, MsgId, Viewtype};
+
+/// A single reaction consisting of multiple emoji sequences.
+///
+/// It is guaranteed to have all emojis sorted and deduplicated inside.
+#[derive(Debug, Default, Clone)]
+pub struct Reaction {
+    /// Canonical represntation of reaction as a string of space-separated emojis.
+    reaction: String,
+}
+
+// We implement From<&str> instead of std::str::FromStr, because
+// FromStr requires error type and reaction parsing never returns an
+// error.
+impl From<&str> for Reaction {
+    /// Parses a string containing a reaction.
+    ///
+    /// Reaction string is separated by spaces or tabs (`WSP` in ABNF),
+    /// but this function accepts any ASCII whitespace, so even a CRLF at
+    /// the end of string is acceptable.
+    ///
+    /// Any short enough string is accepted as a reaction to avoid the
+    /// complexity of validating emoji sequences ase required by RFC
+    /// 9078. On the sender side UI is responsible to provide only
+    /// valid emoji sequences via reaction picker. On the receiver
+    /// side, abuse of the possibility to use arbitrary strings as
+    /// reactions is not different from other kinds of spam attacks
+    /// such as sending large numbers of large messages, and should be
+    /// dealt with the same way, e.g. by blocking the user.
+    fn from(reaction: &str) -> Self {
+        let mut emojis: Vec<&str> = reaction
+            .split_ascii_whitespace()
+            .filter(|&emoji| emoji.len() < 30)
+            .collect();
+        emojis.sort();
+        emojis.dedup();
+        let reaction = emojis.join(" ");
+        Self { reaction }
+    }
+}
+
+impl Reaction {
+    /// Returns true if reaction contains no emojis.
+    pub fn is_empty(&self) -> bool {
+        self.reaction.is_empty()
+    }
+
+    /// Returns a vector of emojis composing a reaction.
+    pub fn emojis(&self) -> Vec<&str> {
+        self.reaction.split(' ').collect()
+    }
+
+    /// Returns space-separated string of emojis
+    pub fn as_str(&self) -> &str {
+        &self.reaction
+    }
+
+    /// Appends emojis from another reaction to this reaction.
+    pub fn add(&self, other: Self) -> Self {
+        let mut emojis: Vec<&str> = self.emojis();
+        emojis.append(&mut other.emojis());
+        emojis.sort();
+        emojis.dedup();
+        let reaction = emojis.join(" ");
+        Self { reaction }
+    }
+}
+
+/// Structure representing all reactions to a particular message.
+#[derive(Debug)]
+pub struct Reactions {
+    /// Map from a contact to its reaction to message.
+    reactions: BTreeMap<ContactId, Reaction>,
+}
+
+impl Reactions {
+    /// Returns vector of contacts that reacted to the message.
+    pub fn contacts(&self) -> Vec<ContactId> {
+        self.reactions.keys().copied().collect()
+    }
+
+    /// Returns reaction of a given contact to message.
+    ///
+    /// If contact did not react to message or removed the reaction,
+    /// this method returns an empty reaction.
+    pub fn get(&self, contact_id: ContactId) -> Reaction {
+        self.reactions.get(&contact_id).cloned().unwrap_or_default()
+    }
+
+    /// Returns true if the message has no reactions.
+    pub fn is_empty(&self) -> bool {
+        self.reactions.is_empty()
+    }
+}
+
+impl fmt::Display for Reactions {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut emoji_frequencies: BTreeMap<String, usize> = BTreeMap::new();
+        for reaction in self.reactions.values() {
+            for emoji in reaction.emojis() {
+                emoji_frequencies
+                    .entry(emoji.to_string())
+                    .and_modify(|x| *x += 1)
+                    .or_insert(1);
+            }
+        }
+        let mut first = true;
+        for (emoji, frequency) in emoji_frequencies {
+            if !first {
+                write!(f, " ")?;
+                first = true;
+            }
+            write!(f, "{}{}", emoji, frequency)?;
+        }
+        Ok(())
+    }
+}
+
+async fn set_msg_id_reaction(
+    context: &Context,
+    msg_id: MsgId,
+    chat_id: ChatId,
+    contact_id: ContactId,
+    reaction: Reaction,
+) -> Result<()> {
+    if reaction.is_empty() {
+        // Simply remove the record instead of setting it to empty string.
+        context
+            .sql
+            .execute(
+                "DELETE FROM reactions
+                 WHERE msg_id = ?1
+                 AND contact_id = ?2",
+                paramsv![msg_id, contact_id],
+            )
+            .await?;
+    } else {
+        context
+            .sql
+            .execute(
+                "INSERT INTO reactions (msg_id, contact_id, reaction)
+                 VALUES (?1, ?2, ?3)
+                 ON CONFLICT(msg_id, contact_id)
+                 DO UPDATE SET reaction=excluded.reaction",
+                paramsv![msg_id, contact_id, reaction.as_str()],
+            )
+            .await?;
+    }
+
+    context.emit_event(EventType::ReactionsChanged {
+        chat_id,
+        msg_id,
+        contact_id,
+    });
+    Ok(())
+}
+
+/// Sends a reaction to message `msg_id`, overriding previously sent reactions.
+///
+/// `reaction` is a string consisting of space-separated emoji. Use
+/// empty string to retract a reaction.
+pub async fn send_reaction(context: &Context, msg_id: MsgId, reaction: &str) -> Result<MsgId> {
+    let msg = Message::load_from_db(context, msg_id).await?;
+    let chat_id = msg.chat_id;
+
+    let reaction: Reaction = reaction.into();
+    let mut reaction_msg = Message::new(Viewtype::Reaction);
+    reaction_msg.text = Some(reaction.as_str().to_string());
+
+    set_msg_id_reaction(context, msg_id, msg.chat_id, ContactId::SELF, reaction).await?;
+    send_msg(context, chat_id, &mut reaction_msg).await
+}
+
+/// Adds given reaction to message `msg_id` and sends an update.
+///
+/// This can be used to implement advanced clients that allow reacting
+/// with multiple emojis. For a simple messenger UI, you probably want
+/// to use [`send_reaction()`] instead so reacing with a new emoji
+/// removes previous emoji at the same time.
+pub async fn add_reaction(context: &Context, msg_id: MsgId, reaction: &str) -> Result<MsgId> {
+    let self_reaction = get_self_reaction(context, msg_id).await?;
+    let reaction = self_reaction.add(Reaction::from(reaction));
+    send_reaction(context, msg_id, reaction.as_str()).await
+}
+
+/// Updates reaction of `contact_id` on the message with `in_reply_to`
+/// Message-ID. If no such message is found in the database, reaction
+/// is ignored.
+///
+/// `reaction` is a space-separated string of emojis. It can be empty
+/// if contact wants to remove all reactions.
+pub(crate) async fn set_msg_reaction(
+    context: &Context,
+    in_reply_to: &str,
+    chat_id: ChatId,
+    contact_id: ContactId,
+    reaction: Reaction,
+) -> Result<()> {
+    if let Some(msg_id) = rfc724_mid_exists(context, in_reply_to).await? {
+        set_msg_id_reaction(context, msg_id, chat_id, contact_id, reaction).await
+    } else {
+        info!(
+            context,
+            "Can't assign reaction to unknown message with Message-ID {}", in_reply_to
+        );
+        Ok(())
+    }
+}
+
+/// Get our own reaction for a given message.
+async fn get_self_reaction(context: &Context, msg_id: MsgId) -> Result<Reaction> {
+    let reaction_str: Option<String> = context
+        .sql
+        .query_get_value(
+            "SELECT reaction
+             FROM reactions
+             WHERE msg_id=? AND contact_id=?",
+            paramsv![msg_id, ContactId::SELF],
+        )
+        .await?;
+    Ok(reaction_str
+        .as_deref()
+        .map(Reaction::from)
+        .unwrap_or_default())
+}
+
+/// Returns a structure containing all reactions to the message.
+pub async fn get_msg_reactions(context: &Context, msg_id: MsgId) -> Result<Reactions> {
+    let reactions = context
+        .sql
+        .query_map(
+            "SELECT contact_id, reaction FROM reactions WHERE msg_id=?",
+            paramsv![msg_id],
+            |row| {
+                let contact_id: ContactId = row.get(0)?;
+                let reaction: String = row.get(1)?;
+                Ok((contact_id, reaction))
+            },
+            |rows| {
+                let mut reactions = Vec::new();
+                for row in rows {
+                    let (contact_id, reaction) = row?;
+                    reactions.push((contact_id, Reaction::from(reaction.as_str())));
+                }
+                Ok(reactions)
+            },
+        )
+        .await?
+        .into_iter()
+        .collect();
+    Ok(Reactions { reactions })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::config::Config;
+    use crate::constants::DC_CHAT_ID_TRASH;
+    use crate::contact::{Contact, Origin};
+    use crate::message::MessageState;
+    use crate::receive_imf::receive_imf;
+    use crate::test_utils::TestContext;
+
+    #[test]
+    fn test_parse_reaction() {
+        // Check that basic set of emojis from RFC 9078 is supported.
+        assert_eq!(Reaction::from("👍").emojis(), vec!["👍"]);
+        assert_eq!(Reaction::from("👎").emojis(), vec!["👎"]);
+        assert_eq!(Reaction::from("😀").emojis(), vec!["😀"]);
+        assert_eq!(Reaction::from("☹").emojis(), vec!["☹"]);
+        assert_eq!(Reaction::from("😢").emojis(), vec!["😢"]);
+
+        // Empty string can be used to remove all reactions.
+        assert!(Reaction::from("").is_empty());
+
+        // Short strings can be used as emojis, could be used to add
+        // support for custom emojis via emoji shortcodes.
+        assert_eq!(Reaction::from(":deltacat:").emojis(), vec![":deltacat:"]);
+
+        // Check that long strings are not valid emojis.
+        assert!(
+            Reaction::from(":foobarbazquuxaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:").is_empty()
+        );
+
+        // Multiple reactions separated by spaces or tabs are supported.
+        assert_eq!(Reaction::from("👍 ❤").emojis(), vec!["❤", "👍"]);
+        assert_eq!(Reaction::from("👍\t❤").emojis(), vec!["❤", "👍"]);
+
+        // Invalid emojis are removed, but valid emojis are retained.
+        assert_eq!(
+            Reaction::from("👍\t:foo: ❤").emojis(),
+            vec![":foo:", "❤", "👍"]
+        );
+        assert_eq!(Reaction::from("👍\t:foo: ❤").as_str(), ":foo: ❤ 👍");
+
+        // Duplicates are removed.
+        assert_eq!(Reaction::from("👍 👍").emojis(), vec!["👍"]);
+    }
+
+    #[test]
+    fn test_add_reaction() {
+        let reaction1 = Reaction::from("👍 😀");
+        let reaction2 = Reaction::from("❤");
+        let reaction_sum = reaction1.add(reaction2);
+
+        assert_eq!(reaction_sum.emojis(), vec!["❤", "👍", "😀"]);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_receive_reaction() -> Result<()> {
+        let alice = TestContext::new_alice().await;
+        alice.set_config(Config::ShowEmails, Some("2")).await?;
+
+        // Alice receives BCC-self copy of a message sent to Bob.
+        receive_imf(
+            &alice,
+            "To: bob@example.net\n\
+From: alice@example.org\n\
+Date: Today, 29 February 2021 00:00:00 -800\n\
+Message-ID: 12345@example.org\n\
+Subject: Meeting\n\
+\n\
+Can we chat at 1pm pacific, today?"
+                .as_bytes(),
+            false,
+        )
+        .await?;
+        let msg = alice.get_last_msg().await;
+        assert_eq!(msg.state, MessageState::OutDelivered);
+        let reactions = get_msg_reactions(&alice, msg.id).await?;
+        let contacts = reactions.contacts();
+        assert_eq!(contacts.len(), 0);
+
+        let bob_id = Contact::add_or_lookup(&alice, "", "bob@example.net", Origin::ManuallyCreated)
+            .await?
+            .0;
+        let bob_reaction = reactions.get(bob_id);
+        assert!(bob_reaction.is_empty()); // Bob has not reacted to message yet.
+
+        // Alice receives reaction to her message from Bob.
+        receive_imf(
+            &alice,
+            "To: alice@example.org\n\
+From: bob@example.net\n\
+Date: Today, 29 February 2021 00:00:10 -800\n\
+Message-ID: 56789@example.net\n\
+In-Reply-To: 12345@example.org\n\
+Subject: Meeting\n\
+Mime-Version: 1.0 (1.0)\n\
+Content-Type: text/plain; charset=utf-8\n\
+Content-Disposition: reaction\n\
+\n\
+\u{1F44D}"
+                .as_bytes(),
+            false,
+        )
+        .await?;
+
+        let reactions = get_msg_reactions(&alice, msg.id).await?;
+        assert_eq!(reactions.to_string(), "👍1");
+
+        let contacts = reactions.contacts();
+        assert_eq!(contacts.len(), 1);
+
+        assert_eq!(contacts.get(0), Some(&bob_id));
+        let bob_reaction = reactions.get(bob_id);
+        assert_eq!(bob_reaction.is_empty(), false);
+        assert_eq!(bob_reaction.emojis(), vec!["👍"]);
+        assert_eq!(bob_reaction.as_str(), "👍");
+
+        Ok(())
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_send_reaction() -> Result<()> {
+        let alice = TestContext::new_alice().await;
+        let bob = TestContext::new_bob().await;
+
+        let chat_alice = alice.create_chat(&bob).await;
+        let alice_msg = alice.send_text(chat_alice.id, "Hi!").await;
+        let bob_msg = bob.recv_msg(&alice_msg).await;
+
+        bob_msg.chat_id.accept(&bob).await?;
+
+        send_reaction(&bob, bob_msg.id, "👍").await.unwrap();
+        let bob_reaction_msg = bob.pop_sent_msg().await;
+        let alice_reaction_msg = alice.recv_msg_opt(&bob_reaction_msg).await.unwrap();
+        assert_eq!(alice_reaction_msg.chat_id, DC_CHAT_ID_TRASH);
+
+        let reactions = get_msg_reactions(&alice, alice_msg.sender_msg_id).await?;
+        assert_eq!(reactions.to_string(), "👍1");
+        let contacts = reactions.contacts();
+        assert_eq!(contacts.len(), 1);
+        let bob_id = contacts.get(0).unwrap();
+        let bob_reaction = reactions.get(*bob_id);
+        assert_eq!(bob_reaction.is_empty(), false);
+        assert_eq!(bob_reaction.emojis(), vec!["👍"]);
+        assert_eq!(bob_reaction.as_str(), "👍");
+
+        Ok(())
+    }
+}

src/receive_imf.rs

@@ -33,6 +33,7 @@ use crate::mimeparser::{
 };
 use crate::param::{Param, Params};
 use crate::peerstate::{Peerstate, PeerstateKeyType, PeerstateVerifiedStatus};
+use crate::reaction::{set_msg_reaction, Reaction};
 use crate::securejoin::{self, handle_securejoin_handshake, observe_securejoin_on_other_device};
 use crate::sql;
 use crate::stock_str;
@@ -430,8 +431,12 @@ async fn add_parts(
     };
     // incoming non-chat messages may be discarded
 
-    let location_kml_is = mime_parser.location_kml.is_some();
+    let is_location_kml = mime_parser.location_kml.is_some();
     let is_mdn = !mime_parser.mdn_reports.is_empty();
+    let is_reaction = mime_parser
+        .parts
+        .iter()
+        .any(|part| part.typ == Viewtype::Reaction);
     let show_emails =
         ShowEmails::from_i32(context.get_config_int(Config::ShowEmails).await?).unwrap_or_default();
 
@@ -689,7 +694,8 @@ async fn add_parts(
         state = if seen
             || fetching_existing_messages
             || is_mdn
-            || location_kml_is
+            || is_reaction
+            || is_location_kml
             || securejoin_seen
             || chat_id_blocked == Blocked::Yes
         {
@@ -841,7 +847,7 @@ async fn add_parts(
         }
     }
 
-    if is_mdn {
+    if is_mdn || is_reaction {
         chat_id = Some(DC_CHAT_ID_TRASH);
     }
 
@@ -1053,6 +1059,17 @@ async fn add_parts(
     let conn = context.sql.get_conn().await?;
 
     for part in &mime_parser.parts {
+        if part.typ == Viewtype::Reaction {
+            set_msg_reaction(
+                context,
+                &mime_in_reply_to,
+                chat_id,
+                from_id,
+                Reaction::from(part.msg.as_str()),
+            )
+            .await?;
+        }
+
         let mut txt_raw = "".to_string();
         let mut stmt = conn.prepare_cached(
             r#"
@@ -1113,7 +1130,7 @@ INSERT INTO msgs
 
         // If you change which information is skipped if the message is trashed,
         // also change `MsgId::trash()` and `delete_expired_messages()`
-        let trash = chat_id.is_trash() || (location_kml_is && msg.is_empty());
+        let trash = chat_id.is_trash() || (is_location_kml && msg.is_empty());
 
         stmt.execute(paramsv![
             rfc724_mid,

src/sql/migrations.rs

@@ -596,6 +596,19 @@ CREATE INDEX smtp_messageid ON imap(rfc724_mid);
         )
         .await?;
     }
+    if dbversion < 92 {
+        sql.execute_migration(
+            r#"CREATE TABLE reactions (
+              msg_id INTEGER NOT NULL, -- id of the message reacted to
+              contact_id INTEGER NOT NULL, -- id of the contact reacting to the message
+              reaction TEXT DEFAULT '' NOT NULL, -- a sequence of emojis separated by spaces
+              PRIMARY KEY(msg_id, contact_id),
+              FOREIGN KEY(msg_id) REFERENCES msgs(id) ON DELETE CASCADE -- delete reactions when message is deleted
+              FOREIGN KEY(contact_id) REFERENCES contacts(id) ON DELETE CASCADE -- delete reactions when contact is deleted
+            )"#,
+            92
+        ).await?;
+    }
 
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)

src/summary.rs

@@ -144,7 +144,7 @@ impl Message {
                     .map(|info| info.name)
                     .unwrap_or_else(|_| "ErrWebxdcName".to_string())
             }
-            Viewtype::Text | Viewtype::Unknown => {
+            Viewtype::Text | Viewtype::Reaction | Viewtype::Unknown => {
                 if self.param.get_cmd() != SystemMessage::LocationOnly {
                     "".to_string()
                 } else {

standards.md

@@ -8,6 +8,7 @@ Transport                        | IMAP v4 ([RFC 3501](https://tools.ietf.org/ht
 Proxy                            | SOCKS5 ([RFC 1928](https://tools.ietf.org/html/rfc1928))
 Embedded media                   | MIME Document Series ([RFC 2045](https://tools.ietf.org/html/rfc2045), [RFC 2046](https://tools.ietf.org/html/rfc2046)), Content-Disposition Header ([RFC 2183](https://tools.ietf.org/html/rfc2183)), Multipart/Related ([RFC 2387](https://tools.ietf.org/html/rfc2387))
 Text and Quote encoding          | Fixed, Flowed ([RFC 3676](https://tools.ietf.org/html/rfc3676))
+Reactions                        | Reaction: Indicating Summary Reaction to a Message [RFC 9078](https://datatracker.ietf.org/doc/rfc9078/)
 Filename encoding                | Encoded Words ([RFC 2047](https://tools.ietf.org/html/rfc2047)), Encoded Word Extensions ([RFC 2231](https://tools.ietf.org/html/rfc2231))
 Identify server folders          | IMAP LIST Extension ([RFC 6154](https://tools.ietf.org/html/rfc6154))
 Push                             | IMAP IDLE ([RFC 2177](https://tools.ietf.org/html/rfc2177))