Merge pull request #11 from xmtp/nm/add-group-extensions

openmls/src/group/core_group/mod.rs

@@ -211,6 +211,14 @@ impl CoreGroupBuilder {
         self
     }
 
+    /// Set the `group_context_extensions` of the [`CoreGroup`].
+    pub fn with_group_context_extensions(mut self, extensions: Extensions) -> Self {
+        self.public_group_builder = self
+            .public_group_builder
+            .with_group_context_extensions(extensions);
+        self
+    }
+
     /// Build the [`CoreGroup`].
     /// Any values that haven't been set in the builder are set to their default
     /// values (which might be random).

openmls/src/group/mls_group/config.rs

@@ -60,6 +60,8 @@ pub struct MlsGroupConfig {
     pub(crate) lifetime: Lifetime,
     /// Ciphersuite and protocol version
     pub(crate) crypto_config: CryptoConfig,
+    // Other extensions
+    pub(crate) group_context_extensions: Extensions,
 }
 
 impl MlsGroupConfig {
@@ -118,6 +120,11 @@ impl MlsGroupConfig {
         &self.crypto_config
     }
 
+    /// Set the `group_context_extensions` property of the MlsGroupConfig.
+    pub fn group_context_extensions(&self) -> &Extensions {
+        &self.group_context_extensions
+    }
+
     #[cfg(any(feature = "test-utils", test))]
     pub fn test_default(ciphersuite: Ciphersuite) -> Self {
         Self::builder()
@@ -220,6 +227,12 @@ impl MlsGroupConfigBuilder {
         self
     }
 
+    /// Sets the `group_context_extensions` property of the MlsGroupConfig.
+    pub fn group_context_extensions(mut self, extensions: Extensions) -> Self {
+        self.config.group_context_extensions = extensions;
+        self
+    }
+
     /// Finalizes the builder and retursn an `[MlsGroupConfig`].
     pub fn build(self) -> MlsGroupConfig {
         self.config

openmls/src/group/mls_group/creation.rs

@@ -57,6 +57,7 @@ impl MlsGroup {
             credential_with_key,
         )
         .with_config(group_config)
+        .with_group_context_extensions(mls_group_config.group_context_extensions.clone())
         .with_required_capabilities(mls_group_config.required_capabilities.clone())
         .with_external_senders(mls_group_config.external_senders.clone())
         .with_max_past_epoch_secrets(mls_group_config.max_past_epochs)

openmls/src/group/mls_group/test_mls_group.rs

@@ -645,3 +645,62 @@ fn remove_prosposal_by_ref(ciphersuite: Ciphersuite, provider: &impl OpenMlsProv
         _ => unreachable!("Expected a StagedCommit."),
     }
 }
+
+#[apply(ciphersuites_and_providers)]
+fn test_group_context_extensions(ciphersuite: Ciphersuite, provider: &impl OpenMlsProvider) {
+    let group_id = GroupId::from_slice(b"Test Group");
+    let application_id = b"Test App ID";
+    let metadata = vec![1, 2, 3];
+
+    let (alice_credential_with_key, _alice_kpb, alice_signer, _alice_pk) =
+        setup_client("Alice", ciphersuite, provider);
+
+    // Define the MlsGroup configuration
+    let mls_group_config = MlsGroupConfig::builder()
+        .wire_format_policy(WireFormatPolicy::new(
+            OutgoingWireFormatPolicy::AlwaysPlaintext,
+            IncomingWireFormatPolicy::Mixed,
+        ))
+        .crypto_config(CryptoConfig::with_default_version(ciphersuite))
+        .group_context_extensions(Extensions::single(Extension::ProtectedMetadata(
+            ProtectedMetadata::new(
+                &alice_signer,
+                application_id.to_vec(),
+                alice_credential_with_key.credential.clone(),
+                alice_credential_with_key.signature_key.as_slice().to_vec(),
+                metadata,
+            )
+            .unwrap(),
+        )))
+        .build();
+
+    // === Alice creates a group ===
+    let mut alice_group = MlsGroup::new_with_group_id(
+        provider,
+        &alice_signer,
+        &mls_group_config,
+        group_id.clone(),
+        alice_credential_with_key,
+    )
+    .expect("An unexpected error occurred.");
+
+    assert!(alice_group
+        .export_group_context()
+        .extensions()
+        .contains(ExtensionType::ProtectedMetadata));
+
+    // Check the internal state has changed
+    assert_eq!(alice_group.state_changed(), InnerState::Changed);
+
+    alice_group
+        .save(provider.key_store())
+        .expect("Could not write group state to file");
+
+    let alice_group_deserialized =
+        MlsGroup::load(&group_id, provider.key_store()).expect("Could not deserialize MlsGroup");
+
+    assert!(alice_group_deserialized
+        .export_group_context()
+        .extensions()
+        .contains(ExtensionType::ProtectedMetadata));
+}

openmls/src/group/public_group/builder.rs

@@ -26,6 +26,7 @@ pub(crate) struct TempBuilderPG1 {
     required_capabilities: Option<RequiredCapabilitiesExtension>,
     external_senders: Option<ExternalSendersExtension>,
     leaf_extensions: Option<Extensions>,
+    group_context_extensions: Option<Extensions>,
 }
 
 impl TempBuilderPG1 {
@@ -34,6 +35,11 @@ impl TempBuilderPG1 {
         self
     }
 
+    pub(crate) fn with_group_context_extensions(mut self, extensions: Extensions) -> Self {
+        self.group_context_extensions = Some(extensions);
+        self
+    }
+
     pub(crate) fn with_required_capabilities(
         mut self,
         required_capabilities: RequiredCapabilitiesExtension,
@@ -87,17 +93,22 @@ impl TempBuilderPG1 {
             _ => LibraryError::custom("Unexpected ExtensionError").into(),
         })?;
         let required_capabilities = Extension::RequiredCapabilities(required_capabilities);
-        let extensions =
-            if let Some(ext_senders) = self.external_senders.map(Extension::ExternalSenders) {
-                vec![required_capabilities, ext_senders]
-            } else {
-                vec![required_capabilities]
-            };
+
+        let mut extensions = Extensions::from_vec(vec![required_capabilities])?;
+        if let Some(ext_senders) = self.external_senders.map(Extension::ExternalSenders) {
+            extensions.add(ext_senders)?;
+        }
+        if let Some(group_context_extensions) = self.group_context_extensions {
+            for extension in group_context_extensions.iter() {
+                extensions.add(extension.clone())?;
+            }
+        }
+
         let group_context = GroupContext::create_initial_group_context(
             self.crypto_config.ciphersuite,
             self.group_id,
             treesync.tree_hash().to_vec(),
-            Extensions::from_vec(extensions)?,
+            extensions,
         );
         let next_builder = TempBuilderPG2 {
             treesync,
@@ -172,6 +183,7 @@ impl PublicGroup {
             required_capabilities: None,
             external_senders: None,
             leaf_extensions: None,
+            group_context_extensions: None,
         }
     }
 }