core_crypto/transaction_context/conversation/
welcome.rs

1//! This module contains transactional conversation operations that produce a [WelcomeBundle].
2
3use std::borrow::BorrowMut as _;
4
5use openmls::prelude::{MlsMessageIn, MlsMessageInBody};
6use tls_codec::Deserialize as _;
7
8use super::{Error, Result, TransactionContext};
9use crate::{
10    MlsConversation, MlsConversationConfiguration, MlsCustomConfiguration, RecursiveError, WelcomeBundle,
11    mls::credential::crl::{extract_crl_uris_from_group, get_new_crl_distribution_points},
12};
13
14impl TransactionContext {
15    /// Create a conversation from a TLS serialized MLS Welcome message. The `MlsConversationConfiguration` used in this function will be the default implementation.
16    ///
17    /// # Arguments
18    /// * `welcome` - a TLS serialized welcome message
19    /// * `configuration` - configuration of the MLS conversation fetched from the Delivery Service
20    ///
21    /// # Return type
22    /// This function will return the conversation/group id
23    ///
24    /// # Errors
25    /// see [TransactionContext::process_welcome_message]
26    #[cfg_attr(test, crate::dispotent)]
27    pub async fn process_raw_welcome_message(
28        &self,
29        welcome: &[u8],
30        custom_cfg: MlsCustomConfiguration,
31    ) -> Result<WelcomeBundle> {
32        let mut cursor = std::io::Cursor::new(welcome);
33        let welcome =
34            MlsMessageIn::tls_deserialize(&mut cursor).map_err(Error::tls_deserialize("mls message in (welcome)"))?;
35        self.process_welcome_message(welcome, custom_cfg).await
36    }
37
38    /// Create a conversation from a received MLS Welcome message
39    ///
40    /// # Arguments
41    /// * `welcome` - a `Welcome` message received as a result of a commit adding new members to a group
42    /// * `configuration` - configuration of the group/conversation
43    ///
44    /// # Return type
45    /// This function will return the conversation/group id
46    ///
47    /// # Errors
48    /// Errors can be originating from the KeyStore of from OpenMls:
49    /// * if no [openmls::key_packages::KeyPackage] can be read from the KeyStore
50    /// * if the message can't be decrypted
51    #[cfg_attr(test, crate::dispotent)]
52    pub async fn process_welcome_message(
53        &self,
54        welcome: MlsMessageIn,
55        custom_cfg: MlsCustomConfiguration,
56    ) -> Result<WelcomeBundle> {
57        let MlsMessageInBody::Welcome(welcome) = welcome.extract() else {
58            return Err(Error::CallerError(
59                "the message provided to process_welcome_message was not a welcome message",
60            ));
61        };
62        let cs = welcome.ciphersuite().into();
63        let configuration = MlsConversationConfiguration {
64            ciphersuite: cs,
65            custom: custom_cfg,
66            ..Default::default()
67        };
68        let mls_provider = self
69            .mls_provider()
70            .await
71            .map_err(RecursiveError::transaction("getting mls provider"))?;
72        let mut mls_groups = self
73            .mls_groups()
74            .await
75            .map_err(RecursiveError::transaction("getting mls groups"))?;
76        let conversation =
77            MlsConversation::from_welcome_message(welcome, configuration, &mls_provider, mls_groups.borrow_mut())
78                .await
79                .map_err(RecursiveError::mls_conversation("creating conversation from welcome"))?;
80
81        // We wait for the group to be created then we iterate through all members
82        let crl_new_distribution_points = get_new_crl_distribution_points(
83            &mls_provider,
84            extract_crl_uris_from_group(&conversation.group)
85                .map_err(RecursiveError::mls_credential("extracting crl uris from group"))?,
86        )
87        .await
88        .map_err(RecursiveError::mls_credential("getting new crl distribution points"))?;
89
90        let id = conversation.id.clone();
91        mls_groups.insert(&id, conversation);
92
93        Ok(WelcomeBundle {
94            id,
95            crl_new_distribution_points,
96        })
97    }
98}
99
100#[cfg(test)]
101mod tests {
102    use super::*;
103    use crate::test_utils::*;
104
105    #[apply(all_cred_cipher)]
106    async fn joining_from_welcome_should_prune_local_key_material(case: TestContext) {
107        let [alice, bob] = case.sessions().await;
108        Box::pin(async move {
109            // has to be before the original key_package count because it creates one
110            // Create a conversation from alice, where she invites bob
111            let commit_guard = case.create_conversation([&alice]).await.invite([&bob]).await;
112
113            // Keep track of the whatever amount was initially generated
114            let prev_count = bob.transaction.count_entities().await;
115            // Bob accepts the welcome message, and as such, it should prune the used keypackage from the store
116            commit_guard.notify_members().await;
117
118            // Ensure we're left with 1 less keypackage bundle in the store, because it was consumed with the OpenMLS Welcome message
119            let next_count = bob.transaction.count_entities().await;
120            assert_eq!(next_count.key_package, prev_count.key_package - 1);
121            assert_eq!(next_count.hpke_private_key, prev_count.hpke_private_key - 1);
122            assert_eq!(next_count.encryption_keypair, prev_count.encryption_keypair - 1);
123        })
124        .await;
125    }
126
127    #[apply(all_cred_cipher)]
128    async fn process_welcome_should_fail_when_already_exists(case: TestContext) {
129        use crate::LeafError;
130
131        let [alice, bob] = case.sessions().await;
132        Box::pin(async move {
133            let commit = case.create_conversation([&alice]).await.invite([&bob]).await;
134            let conversation = commit.conversation();
135            let id = conversation.id().clone();
136                // Meanwhile Bob creates a conversation with the exact same id as the one he's trying to join
137                bob
138                    .transaction
139                    .new_conversation(&id, case.credential_type, case.cfg.clone())
140                    .await
141                    .unwrap();
142
143                let welcome = conversation.transport().await.latest_welcome_message().await;
144                let join_welcome = bob
145                    .transaction
146                    .process_welcome_message(welcome.into(), case.custom_cfg())
147                    .await;
148                assert!(
149                    matches!(join_welcome.unwrap_err(),
150                    Error::Recursive(crate::RecursiveError::MlsConversation { source, .. })
151                        if matches!(*source, crate::mls::conversation::Error::Leaf(LeafError::ConversationAlreadyExists(ref i)) if i == &id
152                        )
153                    )
154                );
155            })
156        .await;
157    }
158}
core_crypto/transaction_context/conversation/welcome.rs

core_crypto/transaction_context/conversation/
welcome.rs
