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
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(
29        &self,
30        welcome: &[u8],
31        custom_cfg: MlsCustomConfiguration,
32    ) -> Result<WelcomeBundle> {
33        let mut cursor = std::io::Cursor::new(welcome);
34        let welcome =
35            MlsMessageIn::tls_deserialize(&mut cursor).map_err(Error::tls_deserialize("mls message in (welcome)"))?;
36        self.process_welcome_message(welcome, custom_cfg).await
37    }
38
39    /// Create a conversation from a received MLS Welcome message
40    ///
41    /// # Arguments
42    /// * `welcome` - a `Welcome` message received as a result of a commit adding new members to a group
43    /// * `configuration` - configuration of the group/conversation
44    ///
45    /// # Return type
46    /// This function will return the conversation/group id
47    ///
48    /// # Errors
49    /// Errors can be originating from the KeyStore of from OpenMls:
50    /// * if no [openmls::key_packages::KeyPackage] can be read from the KeyStore
51    /// * if the message can't be decrypted
52    #[cfg_attr(test, crate::dispotent)]
53    pub async fn process_welcome_message(
54        &self,
55        welcome: MlsMessageIn,
56        custom_cfg: MlsCustomConfiguration,
57    ) -> Result<WelcomeBundle> {
58        let MlsMessageInBody::Welcome(welcome) = welcome.extract() else {
59            return Err(Error::CallerError(
60                "the message provided to process_welcome_message was not a welcome message",
61            ));
62        };
63        let cs = welcome.ciphersuite().into();
64        let configuration = MlsConversationConfiguration {
65            ciphersuite: cs,
66            custom: custom_cfg,
67            ..Default::default()
68        };
69        let mls_provider = self
70            .mls_provider()
71            .await
72            .map_err(RecursiveError::transaction("getting mls provider"))?;
73        let mut mls_groups = self
74            .mls_groups()
75            .await
76            .map_err(RecursiveError::transaction("getting mls groups"))?;
77        let conversation =
78            MlsConversation::from_welcome_message(welcome, configuration, &mls_provider, mls_groups.borrow_mut())
79                .await
80                .map_err(RecursiveError::mls_conversation("creating conversation from welcome"))?;
81
82        // We wait for the group to be created then we iterate through all members
83        let crl_new_distribution_points = get_new_crl_distribution_points(
84            &mls_provider,
85            extract_crl_uris_from_group(&conversation.group)
86                .map_err(RecursiveError::mls_credential("extracting crl uris from group"))?,
87        )
88        .await
89        .map_err(RecursiveError::mls_credential("getting new crl distribution points"))?;
90
91        let id = conversation.id.clone();
92        mls_groups.insert(&id, conversation);
93
94        Ok(WelcomeBundle {
95            id,
96            crl_new_distribution_points,
97        })
98    }
99}
100
101#[cfg(test)]
102mod tests {
103    use super::*;
104    use crate::test_utils::*;
105
106    #[apply(all_cred_cipher)]
107    async fn joining_from_welcome_should_prune_local_key_material(case: TestContext) {
108        let [alice, bob] = case.sessions().await;
109        Box::pin(async move {
110            // has to be before the original key_package count because it creates one
111            // Create a conversation from alice, where she invites bob
112            let commit_guard = case.create_conversation([&alice]).await.invite([&bob]).await;
113
114            // Keep track of the whatever amount was initially generated
115            let prev_count = bob.transaction.count_entities().await;
116            // Bob accepts the welcome message, and as such, it should prune the used keypackage from the store
117            commit_guard.notify_members().await;
118
119            // Ensure we're left with 1 less keypackage bundle in the store, because it was consumed with the OpenMLS
120            // Welcome message
121            let next_count = bob.transaction.count_entities().await;
122            assert_eq!(next_count.key_package, prev_count.key_package - 1);
123            assert_eq!(next_count.hpke_private_key, prev_count.hpke_private_key - 1);
124            assert_eq!(next_count.encryption_keypair, prev_count.encryption_keypair - 1);
125        })
126        .await;
127    }
128
129    #[apply(all_cred_cipher)]
130    async fn process_welcome_should_fail_when_already_exists(case: TestContext) {
131        use crate::LeafError;
132
133        let [alice, bob] = case.sessions().await;
134        Box::pin(async move {
135            let commit = case.create_conversation([&alice]).await.invite([&bob]).await;
136            let conversation = commit.conversation();
137            let id = conversation.id().clone();
138                // Meanwhile Bob creates a conversation with the exact same id as the one he's trying to join
139                bob
140                    .transaction
141                    .new_conversation(&id, case.credential_type, case.cfg.clone())
142                    .await
143                    .unwrap();
144
145                let welcome = conversation.transport().await.latest_welcome_message().await;
146                let join_welcome = bob
147                    .transaction
148                    .process_welcome_message(welcome.into(), case.custom_cfg())
149                    .await;
150                assert!(
151                    matches!(join_welcome.unwrap_err(),
152                    Error::Recursive(crate::RecursiveError::MlsConversation { source, .. })
153                        if matches!(*source, crate::mls::conversation::Error::Leaf(LeafError::ConversationAlreadyExists(ref i)) if i == &id
154                        )
155                    )
156                );
157            })
158        .await;
159    }
160}
core_crypto/transaction_context/conversation/welcome.rs

core_crypto/transaction_context/conversation/
welcome.rs
