add immutable signer builder

Author: ghubertpalo

mithril-aggregator/src/signable_builder/immutable_signable_builder.rs

@@ -0,0 +1,66 @@
+use std::sync::Arc;
+
+use async_trait::async_trait;
+use mithril_common::{
+    digesters::ImmutableDigester,
+    entities::{Beacon, ProtocolMessage, ProtocolMessagePartKey},
+    signable_builder::SignableBuilder,
+    StdResult,
+};
+
+pub struct ImmutableSignableBuilder {
+    immutable_digester: Arc<dyn ImmutableDigester>,
+}
+
+impl ImmutableSignableBuilder {
+    /// Constructor
+    pub fn new(immutable_digester: Arc<dyn ImmutableDigester>) -> Self {
+        Self { immutable_digester }
+    }
+}
+
+#[async_trait]
+impl SignableBuilder<Beacon, ProtocolMessage> for ImmutableSignableBuilder {
+    async fn compute_signable(&self, beacon: Beacon) -> StdResult<ProtocolMessage> {
+        let digest = self.immutable_digester.compute_digest(&beacon).await?;
+        let mut protocol_message = ProtocolMessage::new();
+        protocol_message.set_message_part(ProtocolMessagePartKey::SnapshotDigest, digest);
+
+        Ok(protocol_message)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use async_trait::async_trait;
+    use mithril_common::digesters::{ImmutableDigester, ImmutableDigesterError};
+    use mithril_common::entities::Beacon;
+
+    #[derive(Default)]
+    pub struct ImmutableDigesterImpl;
+
+    #[async_trait]
+    impl ImmutableDigester for ImmutableDigesterImpl {
+        async fn compute_digest(&self, beacon: &Beacon) -> Result<String, ImmutableDigesterError> {
+            Ok(format!("immutable {}", beacon.immutable_file_number))
+        }
+    }
+    #[tokio::test]
+    async fn compute_signable() {
+        let digester = ImmutableDigesterImpl::default();
+        let signable_builder = ImmutableSignableBuilder::new(Arc::new(digester));
+        let protocol_message = signable_builder
+            .compute_signable(Beacon::default())
+            .await
+            .unwrap();
+
+        assert_eq!(
+            &"immutable 0".to_string(),
+            protocol_message
+                .get_message_part(&ProtocolMessagePartKey::SnapshotDigest)
+                .unwrap()
+        );
+    }
+}

mithril-aggregator/src/signable_builder/mod.rs

@@ -1,7 +1,9 @@
 //! The module used for building signables
 
+mod immutable_signable_builder;
 mod mithril_stake_distribution;
 mod signable_builder_service;
 
+pub use immutable_signable_builder::*;
 pub use mithril_stake_distribution::*;
 pub use signable_builder_service::*;

mithril-common/src/entities/beacon.rs

@@ -1,4 +1,5 @@
 use crate::entities::{Epoch, ImmutableFileNumber};
+use crate::signable_builder::Beacon as Beaconable;
 use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256};
 use std::cmp::Ordering;
@@ -18,6 +19,8 @@ pub struct Beacon {
     pub immutable_file_number: ImmutableFileNumber,
 }
 
+impl Beaconable for Beacon {}
+
 /// A BeaconComparison is the result of the comparison between a beacon and an oldest beacon.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum BeaconComparison {