Implement skip_randao_verification and blinded block rewards API (#3540)

## Issue Addressed

https://github.com/ethereum/beacon-APIs/pull/222

## Proposed Changes

Update Lighthouse's randao verification API to match the `beacon-APIs` spec. We implemented the API before spec stabilisation, and it changed slightly in the course of review.

Rather than a flag `verify_randao` taking a boolean value, the new API uses a `skip_randao_verification` flag which takes no argument. The new spec also requires the randao reveal to be present and equal to the point-at-infinity when `skip_randao_verification` is set.

I've also updated the `POST /lighthouse/analysis/block_rewards` API to take blinded blocks as input, as the execution payload is irrelevant and we may want to assess blocks produced by builders.

## Additional Info

This is technically a breaking change, but seeing as I suspect I'm the only one using these parameters/APIs, I think we're OK to include this in a patch release.

common/eth2/src/lib.rs

@@ -1233,17 +1233,17 @@ impl BeaconNodeHttpClient {
         randao_reveal: &SignatureBytes,
         graffiti: Option<&Graffiti>,
     ) -> Result<ForkVersionedResponse<BeaconBlock<T, Payload>>, Error> {
-        self.get_validator_blocks_with_verify_randao(slot, Some(randao_reveal), graffiti, None)
+        self.get_validator_blocks_modular(slot, randao_reveal, graffiti, SkipRandaoVerification::No)
             .await
     }
 
     /// `GET v2/validator/blocks/{slot}`
-    pub async fn get_validator_blocks_with_verify_randao<T: EthSpec, Payload: ExecPayload<T>>(
+    pub async fn get_validator_blocks_modular<T: EthSpec, Payload: ExecPayload<T>>(
         &self,
         slot: Slot,
-        randao_reveal: Option<&SignatureBytes>,
+        randao_reveal: &SignatureBytes,
         graffiti: Option<&Graffiti>,
-        verify_randao: Option<bool>,
+        skip_randao_verification: SkipRandaoVerification,
     ) -> Result<ForkVersionedResponse<BeaconBlock<T, Payload>>, Error> {
         let mut path = self.eth_path(V2)?;
 
@@ -1253,19 +1253,17 @@ impl BeaconNodeHttpClient {
             .push("blocks")
             .push(&slot.to_string());
 
-        if let Some(randao_reveal) = randao_reveal {
-            path.query_pairs_mut()
-                .append_pair("randao_reveal", &randao_reveal.to_string());
-        }
+        path.query_pairs_mut()
+            .append_pair("randao_reveal", &randao_reveal.to_string());
 
         if let Some(graffiti) = graffiti {
             path.query_pairs_mut()
                 .append_pair("graffiti", &graffiti.to_string());
         }
 
-        if let Some(verify_randao) = verify_randao {
+        if skip_randao_verification == SkipRandaoVerification::Yes {
             path.query_pairs_mut()
-                .append_pair("verify_randao", &verify_randao.to_string());
+                .append_pair("skip_randao_verification", "");
         }
 
         self.get(path).await
@@ -1278,25 +1276,22 @@ impl BeaconNodeHttpClient {
         randao_reveal: &SignatureBytes,
         graffiti: Option<&Graffiti>,
     ) -> Result<ForkVersionedResponse<BeaconBlock<T, Payload>>, Error> {
-        self.get_validator_blinded_blocks_with_verify_randao(
+        self.get_validator_blinded_blocks_modular(
             slot,
-            Some(randao_reveal),
+            randao_reveal,
             graffiti,
-            None,
+            SkipRandaoVerification::No,
         )
         .await
     }
 
     /// `GET v1/validator/blinded_blocks/{slot}`
-    pub async fn get_validator_blinded_blocks_with_verify_randao<
-        T: EthSpec,
-        Payload: ExecPayload<T>,
-    >(
+    pub async fn get_validator_blinded_blocks_modular<T: EthSpec, Payload: ExecPayload<T>>(
         &self,
         slot: Slot,
-        randao_reveal: Option<&SignatureBytes>,
+        randao_reveal: &SignatureBytes,
         graffiti: Option<&Graffiti>,
-        verify_randao: Option<bool>,
+        skip_randao_verification: SkipRandaoVerification,
     ) -> Result<ForkVersionedResponse<BeaconBlock<T, Payload>>, Error> {
         let mut path = self.eth_path(V1)?;
 
@@ -1306,19 +1301,17 @@ impl BeaconNodeHttpClient {
             .push("blinded_blocks")
             .push(&slot.to_string());
 
-        if let Some(randao_reveal) = randao_reveal {
-            path.query_pairs_mut()
-                .append_pair("randao_reveal", &randao_reveal.to_string());
-        }
+        path.query_pairs_mut()
+            .append_pair("randao_reveal", &randao_reveal.to_string());
 
         if let Some(graffiti) = graffiti {
             path.query_pairs_mut()
                 .append_pair("graffiti", &graffiti.to_string());
         }
 
-        if let Some(verify_randao) = verify_randao {
+        if skip_randao_verification == SkipRandaoVerification::Yes {
             path.query_pairs_mut()
-                .append_pair("verify_randao", &verify_randao.to_string());
+                .append_key_only("skip_randao_verification");
         }
 
         self.get(path).await

common/eth2/src/types.rs

@@ -658,16 +658,34 @@ pub struct ProposerData {
     pub slot: Slot,
 }
 
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Deserialize)]
 pub struct ValidatorBlocksQuery {
-    pub randao_reveal: Option<SignatureBytes>,
+    pub randao_reveal: SignatureBytes,
     pub graffiti: Option<Graffiti>,
-    #[serde(default = "default_verify_randao")]
-    pub verify_randao: bool,
+    pub skip_randao_verification: SkipRandaoVerification,
 }
 
-fn default_verify_randao() -> bool {
-    true
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Deserialize)]
+#[serde(try_from = "Option<String>")]
+pub enum SkipRandaoVerification {
+    Yes,
+    #[default]
+    No,
+}
+
+/// Parse a `skip_randao_verification` query parameter.
+impl TryFrom<Option<String>> for SkipRandaoVerification {
+    type Error = String;
+
+    fn try_from(opt: Option<String>) -> Result<Self, String> {
+        match opt.as_deref() {
+            None => Ok(SkipRandaoVerification::No),
+            Some("") => Ok(SkipRandaoVerification::Yes),
+            Some(s) => Err(format!(
+                "skip_randao_verification does not take a value, got: {s}"
+            )),
+        }
+    }
 }
 
 #[derive(Clone, Serialize, Deserialize)]