events: Use a string for SessionDescription's type

A clarification in MSC2746 / Matrix 1.7 explains that the `type` field
should not be validated but passed as-is to the WebRTC API.
It
    also avoids an unnecessary conversion between the WebRTC API
and the Ruma type.

crates/ruma-common/CHANGELOG.md

@@ -13,6 +13,11 @@ Breaking changes:
 - Remove the `DontNotify` and `Coalesce` variants of `push::Action` according to MSC3987
   - Old push rules will still deserialize successfully but the `Coalesce` variant will not return
     `true` for `Action::should_notify()` anymore
+- Remove `AnswerSessionDescription` and `OfferSessionDescription` types, use `SessionDescription`
+  instead.
+  - Remove `SessionDescriptionType`, use a `String` instead. A clarification in MSC2746 / Matrix 1.7
+    explains that the `type` field should not be validated but passed as-is to the WebRTC API. It
+    also avoids an unnecessary conversion between the WebRTC API and the Ruma type.
 
 Improvements:
 

crates/ruma-common/src/events/call.rs

@@ -15,8 +15,6 @@ pub mod select_answer;
 
 use serde::{Deserialize, Serialize};
 
-use crate::{serde::StringEnum, PrivOwnedStr};
-
 /// A VoIP session description.
 ///
 /// This is the same type as WebRTC's [`RTCSessionDescriptionInit`].
@@ -26,8 +24,10 @@ use crate::{serde::StringEnum, PrivOwnedStr};
 #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
 pub struct SessionDescription {
     /// The type of session description.
+    ///
+    /// This is the `type` field of `RTCSessionDescriptionInit`.
     #[serde(rename = "type")]
-    pub session_type: SessionDescriptionType,
+    pub session_type: String,
 
     /// The SDP text of the session description.
     ///
@@ -39,73 +39,11 @@ pub struct SessionDescription {
 
 impl SessionDescription {
     /// Creates a new `SessionDescription` with the given session type and SDP text.
-    pub fn new(session_type: SessionDescriptionType, sdp: String) -> Self {
+    pub fn new(session_type: String, sdp: String) -> Self {
         Self { session_type, sdp }
     }
 }
 
-/// The type of VoIP session description.
-///
-/// This is the same type as WebRTC's [`RTCSdpType`].
-///
-/// [`RTCSdpType`]: (https://www.w3.org/TR/webrtc/#dom-rtcsdptype):
-#[doc = include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/src/doc/string_enum.md"))]
-#[derive(Clone, PartialEq, Eq, StringEnum)]
-#[ruma_enum(rename_all = "lowercase")]
-#[non_exhaustive]
-pub enum SessionDescriptionType {
-    /// The description must be treated as an SDP final answer, and the offer-answer exchange must
-    /// be considered complete.
-    Answer,
-
-    /// The description must be treated as an SDP offer.
-    Offer,
-
-    /// The description must be treated as an SDP answer, but not final.
-    #[cfg(feature = "unstable-msc2746")]
-    PrAnswer,
-
-    /// The description must be treated as cancelling the current SDP negotiation and moving the
-    /// SDP offer back to what it was in the previous stable state.
-    #[cfg(feature = "unstable-msc2746")]
-    Rollback,
-
-    #[doc(hidden)]
-    _Custom(PrivOwnedStr),
-}
-
-/// A VoIP answer session description.
-#[derive(Clone, Debug, Deserialize, Serialize)]
-#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
-#[serde(tag = "type", rename = "answer")]
-pub struct AnswerSessionDescription {
-    /// The SDP text of the session description.
-    pub sdp: String,
-}
-
-impl AnswerSessionDescription {
-    /// Creates a new `AnswerSessionDescription` with the given SDP text.
-    pub fn new(sdp: String) -> Self {
-        Self { sdp }
-    }
-}
-
-/// A VoIP offer session description.
-#[derive(Clone, Debug, Deserialize, Serialize)]
-#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
-#[serde(tag = "type", rename = "offer")]
-pub struct OfferSessionDescription {
-    /// The SDP text of the session description.
-    pub sdp: String,
-}
-
-impl OfferSessionDescription {
-    /// Creates a new `OfferSessionDescription` with the given SDP text.
-    pub fn new(sdp: String) -> Self {
-        Self { sdp }
-    }
-}
-
 /// The capabilities of a client in a VoIP call.
 #[cfg(feature = "unstable-msc2747")]
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]

crates/ruma-common/src/events/call/answer.rs

@@ -5,9 +5,9 @@
 use ruma_macros::EventContent;
 use serde::{Deserialize, Serialize};
 
-use super::AnswerSessionDescription;
 #[cfg(feature = "unstable-msc2747")]
 use super::CallCapabilities;
+use super::SessionDescription;
 use crate::{OwnedVoipId, VoipVersionId};
 
 /// The content of an `m.call.answer` event.
@@ -18,7 +18,7 @@ use crate::{OwnedVoipId, VoipVersionId};
 #[ruma_event(type = "m.call.answer", kind = MessageLike)]
 pub struct CallAnswerEventContent {
     /// The VoIP session description object.
-    pub answer: AnswerSessionDescription,
+    pub answer: SessionDescription,
 
     /// A unique identifier for the call.
     pub call_id: OwnedVoipId,
@@ -39,11 +39,7 @@ pub struct CallAnswerEventContent {
 
 impl CallAnswerEventContent {
     /// Creates an `CallAnswerEventContent` with the given answer, call ID and VoIP version.
-    pub fn new(
+    pub fn new(answer: SessionDescription, call_id: OwnedVoipId, version: VoipVersionId) -> Self {
-        answer: AnswerSessionDescription,
-        call_id: OwnedVoipId,
-        version: VoipVersionId,
-    ) -> Self {
         Self {
             answer,
             call_id,
@@ -57,7 +53,7 @@ impl CallAnswerEventContent {
 
     /// Convenience method to create a VoIP version 0 `CallAnswerEventContent` with all the required
     /// fields.
-    pub fn version_0(answer: AnswerSessionDescription, call_id: OwnedVoipId) -> Self {
+    pub fn version_0(answer: SessionDescription, call_id: OwnedVoipId) -> Self {
         Self::new(answer, call_id, VoipVersionId::V0)
     }
 
@@ -65,7 +61,7 @@ impl CallAnswerEventContent {
     /// fields.
     #[cfg(feature = "unstable-msc2746")]
     pub fn version_1(
-        answer: AnswerSessionDescription,
+        answer: SessionDescription,
         call_id: OwnedVoipId,
         party_id: OwnedVoipId,
     ) -> Self {

crates/ruma-common/src/events/call/invite.rs

@@ -8,7 +8,7 @@ use serde::{Deserialize, Serialize};
 
 #[cfg(feature = "unstable-msc2747")]
 use super::CallCapabilities;
-use super::OfferSessionDescription;
+use super::SessionDescription;
 #[cfg(feature = "unstable-msc2746")]
 use crate::OwnedUserId;
 use crate::{OwnedVoipId, VoipVersionId};
@@ -35,7 +35,7 @@ pub struct CallInviteEventContent {
     pub lifetime: UInt,
 
     /// The session description object.
-    pub offer: OfferSessionDescription,
+    pub offer: SessionDescription,
 
     /// The version of the VoIP specification this messages adheres to.
     pub version: VoipVersionId,
@@ -61,7 +61,7 @@ impl CallInviteEventContent {
     pub fn new(
         call_id: OwnedVoipId,
         lifetime: UInt,
-        offer: OfferSessionDescription,
+        offer: SessionDescription,
         version: VoipVersionId,
     ) -> Self {
         Self {
@@ -80,7 +80,7 @@ impl CallInviteEventContent {
 
     /// Convenience method to create a version 0 `CallInviteEventContent` with all the required
     /// fields.
-    pub fn version_0(call_id: OwnedVoipId, lifetime: UInt, offer: OfferSessionDescription) -> Self {
+    pub fn version_0(call_id: OwnedVoipId, lifetime: UInt, offer: SessionDescription) -> Self {
         Self::new(call_id, lifetime, offer, VoipVersionId::V0)
     }
 
@@ -91,7 +91,7 @@ impl CallInviteEventContent {
         call_id: OwnedVoipId,
         party_id: OwnedVoipId,
         lifetime: UInt,
-        offer: OfferSessionDescription,
+        offer: SessionDescription,
     ) -> Self {
         Self {
             call_id,

crates/ruma-common/tests/events/call.rs

@@ -8,7 +8,7 @@ use ruma_common::{
             candidates::{CallCandidatesEventContent, Candidate},
             hangup::CallHangupEventContent,
             invite::CallInviteEventContent,
-            AnswerSessionDescription, OfferSessionDescription,
+            SessionDescription,
         },
         AnyMessageLikeEvent, AnySyncMessageLikeEvent, MessageLikeEvent,
     },
@@ -21,7 +21,7 @@ use serde_json::{from_value as from_json_value, json, to_value as to_json_value}
 #[test]
 fn answer_content_serialization() {
     let event_content = CallAnswerEventContent::version_0(
-        AnswerSessionDescription::new("not a real sdp".to_owned()),
+        SessionDescription::new("answer".to_owned(), "not a real sdp".to_owned()),
         "abcdef".into(),
     );
 
@@ -51,6 +51,7 @@ fn answer_content_deserialization() {
 
     let content = from_json_value::<CallAnswerEventContent>(json_data).unwrap();
 
+    assert_eq!(content.answer.session_type, "answer");
     assert_eq!(content.answer.sdp, "Hello");
     assert_eq!(content.call_id, "foofoo");
     assert_eq!(content.version, VoipVersionId::V0);
@@ -85,6 +86,7 @@ fn answer_event_deserialization() {
     assert!(message_event.unsigned.is_empty());
 
     let content = message_event.content;
+    assert_eq!(content.answer.session_type, "answer");
     assert_eq!(content.answer.sdp, "Hello");
     assert_eq!(content.call_id, "foofoo");
     assert_eq!(content.version, VoipVersionId::V0);
@@ -131,7 +133,7 @@ fn invite_content_serialization() {
     let event_content = CallInviteEventContent::version_0(
         "abcdef".into(),
         uint!(30000),
-        OfferSessionDescription::new("not a real sdp".to_owned()),
+        SessionDescription::new("offer".to_owned(), "not a real sdp".to_owned()),
     );
 
     assert_eq!(
@@ -203,8 +205,7 @@ mod msc2746 {
                 negotiate::CallNegotiateEventContent,
                 reject::CallRejectEventContent,
                 select_answer::CallSelectAnswerEventContent,
-                AnswerSessionDescription, OfferSessionDescription, SessionDescription,
+                SessionDescription,
-                SessionDescriptionType,
             },
             AnyMessageLikeEvent, MessageLikeEvent,
         },
@@ -218,7 +219,7 @@ mod msc2746 {
             "abcdef".into(),
             "9876".into(),
             uint!(60000),
-            OfferSessionDescription::new("not a real sdp".to_owned()),
+            SessionDescription::new("offer".to_owned(), "not a real sdp".to_owned()),
         );
 
         assert_eq!(
@@ -266,13 +267,14 @@ mod msc2746 {
         assert_eq!(content.party_id.unwrap(), "9876");
         assert_eq!(content.lifetime, uint!(60000));
         assert_eq!(content.version, VoipVersionId::V1);
+        assert_eq!(content.offer.session_type, "offer");
         assert_eq!(content.offer.sdp, "not a real sdp");
     }
 
     #[test]
     fn answer_event_serialization() {
         let content = CallAnswerEventContent::version_1(
-            AnswerSessionDescription::new("not a real sdp".to_owned()),
+            SessionDescription::new("answer".to_owned(), "not a real sdp".to_owned()),
             "abcdef".into(),
             "9876".into(),
         );
@@ -296,7 +298,7 @@ mod msc2746 {
     fn answer_event_capabilities_serialization() {
         let content = assign!(
             CallAnswerEventContent::version_1(
-                AnswerSessionDescription::new("not a real sdp".to_owned()),
+                SessionDescription::new("answer".to_owned(), "not a real sdp".to_owned()),
                 "abcdef".into(),
                 "9876".into()
             ),
@@ -353,6 +355,7 @@ mod msc2746 {
         assert_eq!(content.call_id, "abcdef");
         assert_eq!(content.party_id.unwrap(), "9876");
         assert_eq!(content.version.as_ref(), "org.matrix.1b");
+        assert_eq!(content.answer.session_type, "answer");
         assert_eq!(content.answer.sdp, "not a real sdp");
         #[cfg(feature = "unstable-msc2747")]
         assert!(content.capabilities.dtmf);
@@ -485,7 +488,7 @@ mod msc2746 {
             "abcdef".into(),
             "9876".into(),
             uint!(30000),
-            SessionDescription::new(SessionDescriptionType::Offer, "not a real sdp".to_owned()),
+            SessionDescription::new("offer".to_owned(), "not a real sdp".to_owned()),
         );
 
         assert_eq!(
@@ -512,7 +515,7 @@ mod msc2746 {
                 "version": "1",
                 "lifetime": 30000,
                 "description": {
-                    "type": "pranswer",
+                    "type": "answer",
                     "sdp": "not a real sdp",
                 }
             },
@@ -532,7 +535,7 @@ mod msc2746 {
         assert_eq!(content.call_id, "abcdef");
         assert_eq!(content.party_id, "9876");
         assert_eq!(content.lifetime, uint!(30000));
-        assert_eq!(content.description.session_type, SessionDescriptionType::PrAnswer);
+        assert_eq!(content.description.session_type, "answer");
         assert_eq!(content.description.sdp, "not a real sdp");
     }