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

core_crypto/transaction_context/conversation/
welcome.rs
