Add attestation production to BeaconChain

beacon_node/beacon_chain/src/attestation_production.rs

@@ -0,0 +1,53 @@
+use super::{BeaconChain, ClientDB, SlotClock};
+use types::{AttestationData, Hash256};
+
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    /*
+    DBError(String),
+    StateTransitionError(TransitionError),
+    PresentSlotIsNone,
+    */
+    SlotTooOld,
+    PresentSlotUnknown,
+    StateError,
+}
+
+impl<T, U> BeaconChain<T, U>
+where
+    T: ClientDB,
+    U: SlotClock,
+{
+    pub fn produce_attestation_data(
+        &self,
+        slot: u64,
+        shard: u64,
+    ) -> Result<AttestationData, Error> {
+        let present_slot = self
+            .present_slot()
+            .ok_or_else(|| Error::PresentSlotUnknown)?;
+        let state = self.state(present_slot).map_err(|_| Error::StateError)?;
+
+        let justified_slot = self.justified_slot();
+
+        let justified_block_root = *state
+            .get_block_root(justified_slot, &self.spec)
+            .ok_or_else(|| Error::SlotTooOld)?;
+
+        let head_slot = self.head().beacon_block.slot;
+        let epoch_boundary_root = *state
+            .get_block_root(head_slot % self.spec.epoch_length, &self.spec)
+            .ok_or_else(|| Error::SlotTooOld)?;
+
+        Ok(AttestationData {
+            slot,
+            shard,
+            beacon_block_root: self.head().beacon_block_root.clone(),
+            epoch_boundary_root,
+            shard_block_root: Hash256::zero(),
+            latest_crosslink_root: Hash256::zero(),
+            justified_slot,
+            justified_block_root,
+        })
+    }
+}

beacon_node/beacon_chain/src/lib.rs

@@ -1,3 +1,4 @@
+mod attestation_production;
 mod attestation_targets;
 mod block_graph;
 pub mod block_processing;