First compiling version of per-block-proc refactor

eth2/state_processing/src/per_block_processing/verify_exit.rs

@@ -0,0 +1,41 @@
+use crate::errors::{ExitInvalid as Invalid, ExitValidationError as Error};
+use ssz::SignedRoot;
+use types::*;
+
+/// Verify validity of ``slashable_attestation`` fields.
+///
+/// Returns `Ok(())` if all fields are valid.
+///
+/// Spec v0.4.0
+pub fn verify_exit(
+    state: &BeaconState,
+    exit: &VoluntaryExit,
+    spec: &ChainSpec,
+) -> Result<(), Error> {
+    let validator = state
+        .validator_registry
+        .get(exit.validator_index as usize)
+        .ok_or(Error::Invalid(Invalid::ValidatorUnknown))?;
+
+    verify!(
+        validator.exit_epoch
+            > state.get_delayed_activation_exit_epoch(state.current_epoch(spec), spec),
+        Invalid::AlreadyExited
+    );
+
+    verify!(
+        state.current_epoch(spec) >= exit.epoch,
+        Invalid::FutureEpoch
+    );
+
+    let message = exit.signed_root();
+    let domain = spec.get_domain(exit.epoch, Domain::Exit, &state.fork);
+
+    verify!(
+        exit.signature
+            .verify(&message[..], domain, &validator.pubkey),
+        Invalid::BadSignature
+    );
+
+    Ok(())
+}