From ab61e975bf1912e3c012d90f882e5571e7dab963 Mon Sep 17 00:00:00 2001
From: Nikita Vilunov <nikita@vilunov.me>
Date: Sat, 6 Apr 2024 15:28:46 +0000
Subject: [PATCH] xmpp: send correct errors on unknown iqs

---
 crates/projection-xmpp/src/iq.rs |  6 +++--
 crates/proto-xmpp/src/client.rs  | 38 ++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/crates/projection-xmpp/src/iq.rs b/crates/projection-xmpp/src/iq.rs
index 3ad0ae5..9c50ecc 100644
--- a/crates/projection-xmpp/src/iq.rs
+++ b/crates/projection-xmpp/src/iq.rs
@@ -4,7 +4,7 @@ use quick_xml::events::Event;
 
 use lavina_core::room::RoomRegistry;
 use proto_xmpp::bind::{BindResponse, Jid, Name, Resource, Server};
-use proto_xmpp::client::{Iq, IqType};
+use proto_xmpp::client::{Iq, IqError, IqErrorType, IqType};
 use proto_xmpp::disco::{Feature, Identity, InfoQuery, Item, ItemQuery};
 use proto_xmpp::roster::RosterQuery;
 use proto_xmpp::session::Session;
@@ -79,7 +79,9 @@ impl<'a> XmppConnection<'a> {
                     id: iq.id,
                     to: None,
                     r#type: IqType::Error,
-                    body: (),
+                    body: IqError {
+                        r#type: IqErrorType::Cancel,
+                    },
                 };
                 req.serialize(output);
             }
diff --git a/crates/proto-xmpp/src/client.rs b/crates/proto-xmpp/src/client.rs
index 8276d7c..4943283 100644
--- a/crates/proto-xmpp/src/client.rs
+++ b/crates/proto-xmpp/src/client.rs
@@ -255,6 +255,44 @@ impl MessageType {
     }
 }
 
+/// Error response to an IQ request.
+///
+/// https://xmpp.org/rfcs/rfc6120.html#stanzas-error
+pub struct IqError {
+    pub r#type: IqErrorType,
+}
+
+pub enum IqErrorType {
+    /// Retry after providing credentials
+    Auth,
+    /// Do not retry (the error cannot be remedied)
+    Cancel,
+    /// Proceed (the condition was only a warning)
+    Continue,
+    /// Retry after changing the data sent
+    Modify,
+    /// Retry after waiting (the error is temporary)
+    Wait,
+}
+impl IqErrorType {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            IqErrorType::Auth => "auth",
+            IqErrorType::Cancel => "cancel",
+            IqErrorType::Continue => "continue",
+            IqErrorType::Modify => "modify",
+            IqErrorType::Wait => "wait",
+        }
+    }
+}
+
+impl ToXml for IqError {
+    fn serialize(&self, events: &mut Vec<Event<'static>>) {
+        let bytes = BytesStart::new(format!(r#"error xmlns="{}" type="{}""#, XMLNS, self.r#type.as_str()));
+        events.push(Event::Empty(bytes));
+    }
+}
+
 #[derive(PartialEq, Eq, Debug)]
 pub struct Iq<T> {
     pub from: Option<String>,