Support receiving own proposals without an error

mls-rs-uniffi/src/lib.rs

@@ -271,6 +271,8 @@ pub enum ReceivedMessage {
         proposal: Arc<Proposal>,
     },
 
+    /// A proposal previously sent by this member was received.
+    OwnProposal,
     /// Validated GroupInfo object.
     GroupInfo,
     /// Validated welcome message.
@@ -771,6 +773,7 @@ impl Group {
                 let proposal = Arc::new(proposal_message.proposal.into());
                 Ok(ReceivedMessage::ReceivedProposal { sender, proposal })
             }
+            group::ReceivedMessage::OwnProposal => Ok(ReceivedMessage::OwnProposal),
             // TODO: group::ReceivedMessage::GroupInfo does not have any
             // public methods (unless the "ffi" Cargo feature is set).
             // So perhaps we don't need it?

mls-rs/src/external_client/group.rs

@@ -450,22 +450,23 @@ impl<C: ExternalClientConfig + Clone> ExternalGroup<C> {
         )
         .await?;
 
-        self.state.proposals.insert(
-            ProposalRef::from_content(&self.cipher_suite_provider, &auth_content).await?,
-            proposal,
-            sender,
-        );
+        let proposal_ref =
+            ProposalRef::from_content(&self.cipher_suite_provider, &auth_content).await?;
 
         let plaintext = PublicMessage {
             content: auth_content.content,
             auth: auth_content.auth,
             membership_tag: None,
         };
 
-        Ok(MlsMessage::new(
+        let message = MlsMessage::new(
             self.group_context().version(),
             MlsMessagePayload::Plain(plaintext),
-        ))
+        );
+
+        self.state.proposals.insert(proposal_ref, proposal, sender);
+
+        Ok(message)
     }
 
     /// Delete all sent and received proposals cached for commit.
@@ -587,7 +588,6 @@ where
             &self.cipher_suite_provider,
             message,
             None,
-            None,
             &self.state,
         )
         .await?;

mls-rs/src/group/commit.rs

@@ -4,12 +4,9 @@
 
 use alloc::vec;
 use alloc::vec::Vec;
-use core::fmt::{self, Debug};
+use core::fmt::Debug;
 use mls_rs_codec::{MlsDecode, MlsEncode, MlsSize};
-use mls_rs_core::{
-    crypto::{CipherSuiteProvider, SignatureSecretKey},
-    error::IntoAnyError,
-};
+use mls_rs_core::{crypto::SignatureSecretKey, error::IntoAnyError};
 
 use crate::{
     cipher_suite::CipherSuite,
@@ -43,6 +40,7 @@ use super::{
     confirmation_tag::ConfirmationTag,
     framing::{Content, MlsMessage, MlsMessagePayload, Sender},
     key_schedule::{KeySchedule, WelcomeSecret},
+    message_hash::MessageHash,
     message_processor::{path_update_required, MessageProcessor},
     message_signature::AuthenticatedContent,
     mls_rules::CommitDirection,
@@ -71,36 +69,7 @@ pub(super) struct CommitGeneration {
     pub content: AuthenticatedContent,
     pub pending_private_tree: TreeKemPrivate,
     pub pending_commit_secret: PathSecret,
-    pub commit_message_hash: CommitHash,
-}
-
-#[derive(Clone, PartialEq, MlsEncode, MlsDecode, MlsSize)]
-#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-pub(crate) struct CommitHash(
-    #[mls_codec(with = "mls_rs_codec::byte_vec")]
-    #[cfg_attr(feature = "serde", serde(with = "mls_rs_core::vec_serde"))]
-    Vec<u8>,
-);
-
-impl Debug for CommitHash {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        mls_rs_core::debug::pretty_bytes(&self.0)
-            .named("CommitHash")
-            .fmt(f)
-    }
-}
-
-impl CommitHash {
-    #[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
-    pub(crate) async fn compute<CS: CipherSuiteProvider>(
-        cs: &CS,
-        commit: &MlsMessage,
-    ) -> Result<Self, MlsError> {
-        cs.hash(&commit.mls_encode_to_vec()?)
-            .await
-            .map_err(|e| MlsError::CryptoProviderError(e.into_any_error()))
-            .map(Self)
-    }
+    pub commit_message_hash: MessageHash,
 }
 
 #[cfg_attr(
@@ -760,7 +729,7 @@ where
             content: auth_content,
             pending_private_tree: provisional_private_tree,
             pending_commit_secret: commit_secret,
-            commit_message_hash: CommitHash::compute(&self.cipher_suite_provider, &commit_message)
+            commit_message_hash: MessageHash::compute(&self.cipher_suite_provider, &commit_message)
                 .await?,
         };
 

mls-rs/src/group/external_commit.rs

@@ -233,9 +233,7 @@ impl<C: ClientConfig> ExternalCommitBuilder<C> {
             };
 
             let auth_content = AuthenticatedContent::from(plaintext.clone());
-
-            verify_plaintext_authentication(&cipher_suite, plaintext, None, None, &group.state)
-                .await?;
+            verify_plaintext_authentication(&cipher_suite, plaintext, None, &group.state).await?;
 
             group
                 .process_event_or_content(EventOrContent::Content(auth_content), true, None)

mls-rs/src/group/message_hash.rs

@@ -0,0 +1,36 @@
+use core::fmt::Debug;
+
+use core::fmt;
+use mls_rs_codec::{MlsDecode, MlsEncode, MlsSize};
+use mls_rs_core::crypto::CipherSuiteProvider;
+
+use crate::{client::MlsError, error::IntoAnyError, MlsMessage};
+
+#[derive(Clone, PartialEq, Eq, MlsEncode, MlsDecode, MlsSize)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub(crate) struct MessageHash(
+    #[mls_codec(with = "mls_rs_codec::byte_vec")]
+    #[cfg_attr(feature = "serde", serde(with = "mls_rs_core::vec_serde"))]
+    Vec<u8>,
+);
+
+impl Debug for MessageHash {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        mls_rs_core::debug::pretty_bytes(&self.0)
+            .named("CommitHash")
+            .fmt(f)
+    }
+}
+
+impl MessageHash {
+    #[cfg_attr(not(mls_build_async), maybe_async::must_be_sync)]
+    pub(crate) async fn compute<CS: CipherSuiteProvider>(
+        cs: &CS,
+        message: &MlsMessage,
+    ) -> Result<Self, MlsError> {
+        cs.hash(&message.mls_encode_to_vec()?)
+            .await
+            .map_err(|e| MlsError::CryptoProviderError(e.into_any_error()))
+            .map(Self)
+    }
+}

mls-rs/src/group/message_processor.rs

@@ -187,6 +187,8 @@ pub enum ReceivedMessage {
     Commit(CommitMessageDescription),
     /// A proposal was received.
     Proposal(ProposalMessageDescription),
+    /// A proposal previously sent by this member was received.
+    OwnProposal,
     /// Validated GroupInfo object
     GroupInfo(GroupInfo),
     /// Validated welcome message

mls-rs/src/group/message_verifier.rs

@@ -38,7 +38,6 @@ pub(crate) async fn verify_plaintext_authentication<P: CipherSuiteProvider>(
     cipher_suite_provider: &P,
     plaintext: PublicMessage,
     key_schedule: Option<&KeySchedule>,
-    self_index: Option<LeafIndex>,
     state: &GroupState,
 ) -> Result<AuthenticatedContent, MlsError> {
     let tag = plaintext.membership_tag.clone();
@@ -52,7 +51,7 @@ pub(crate) async fn verify_plaintext_authentication<P: CipherSuiteProvider>(
 
     // Verify the membership tag if needed
     match &auth_content.content.sender {
-        Sender::Member(index) => {
+        Sender::Member(_) => {
             if let Some(key_schedule) = key_schedule {
                 let expected_tag = &key_schedule
                     .get_membership_tag(&auth_content, context, cipher_suite_provider)
@@ -64,10 +63,6 @@ pub(crate) async fn verify_plaintext_authentication<P: CipherSuiteProvider>(
                     return Err(MlsError::InvalidMembershipTag);
                 }
             }
-
-            if self_index == Some(LeafIndex(*index)) {
-                return Err(MlsError::CantProcessMessageFromSelf);
-            }
         }
         _ => {
             tag.is_none()
@@ -333,7 +328,6 @@ mod tests {
             &env.bob.group.cipher_suite_provider,
             message,
             Some(&env.bob.group.key_schedule),
-            None,
             &env.bob.group.state,
         )
         .await
@@ -381,7 +375,6 @@ mod tests {
             &env.bob.group.cipher_suite_provider,
             message,
             Some(&env.bob.group.key_schedule),
-            None,
             &env.bob.group.state,
         )
         .await;
@@ -399,7 +392,6 @@ mod tests {
             &env.bob.group.cipher_suite_provider,
             message,
             Some(&env.bob.group.key_schedule),
-            None,
             &env.bob.group.state,
         )
         .await;
@@ -417,7 +409,6 @@ mod tests {
             &env.bob.group.cipher_suite_provider,
             message,
             Some(&env.bob.group.key_schedule),
-            None,
             &env.bob.group.state,
         )
         .await;
@@ -485,7 +476,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await
@@ -506,7 +496,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await;
@@ -532,7 +521,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await;
@@ -556,7 +544,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await;
@@ -601,7 +588,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await
@@ -625,7 +611,6 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await;
@@ -652,29 +637,10 @@ mod tests {
             &test_group.group.cipher_suite_provider,
             message,
             Some(&test_group.group.key_schedule),
-            None,
             &test_group.group.state,
         )
         .await;
 
         assert_matches!(res, Err(MlsError::MembershipTagForNonMember));
     }
-
-    #[maybe_async::test(not(mls_build_async), async(mls_build_async, crate::futures_test))]
-    async fn plaintext_from_self_fails_verification() {
-        let mut env = TestEnv::new().await;
-
-        let message = make_signed_plaintext(&mut env.alice.group).await;
-
-        let res = verify_plaintext_authentication(
-            &env.alice.group.cipher_suite_provider,
-            message,
-            Some(&env.alice.group.key_schedule),
-            Some(LeafIndex::new(env.alice.group.current_member_index())),
-            &env.alice.group.state,
-        )
-        .await;
-
-        assert_matches!(res, Err(MlsError::CantProcessMessageFromSelf))
-    }
 }