Fix panic in evidence serialization

CHANGELOG.md

@@ -1,3 +1,12 @@
+## Unreleased
+
+### BUG FIXES
+
+* `[tendermint-proto]` Fix panic in evidence serialization in the case where we
+ receive an empty evidence Protobuf structure ([#782])
+
+[#782]: https://github.com/informalsystems/tendermint-rs/issues/782
+
 ## v0.18.0
 
 *Jan 29, 2021*

proto/src/serializers/evidence.rs

@@ -8,6 +8,8 @@ use crate::tendermint::types::Evidence;
 #[derive(Clone, PartialEq, ::serde::Deserialize, ::serde::Serialize)]
 #[serde(tag = "type", content = "value")]
 pub enum EvidenceVariant {
+ /// Provided for when the evidence struct's optional `sum` field is `None`.
+ None,
  #[serde(rename = "tendermint/DuplicateVoteEvidence")]
  DuplicateVoteEvidence(crate::tendermint::types::DuplicateVoteEvidence),
  #[serde(rename = "tendermint/LightClientAttackEvidence")]
@@ -17,34 +19,56 @@ pub enum EvidenceVariant {
 impl From<EvidenceVariant> for Evidence {
  fn from(value: EvidenceVariant) -> Self {
  match value {
- EvidenceVariant::DuplicateVoteEvidence(d) => Evidence {
- sum: Some(Sum::DuplicateVoteEvidence(d)),
- },
- EvidenceVariant::LightClientAttackEvidence(l) => Evidence {
- sum: Some(Sum::LightClientAttackEvidence(l)),
+ EvidenceVariant::None => Evidence { sum: None },
+ _ => Evidence {
+ sum: Some(value.into()),
  },
  }
  }
 }
 
 impl From<Evidence> for EvidenceVariant {
  fn from(value: Evidence) -> Self {
- let sum = value.sum.unwrap(); // Todo: Error handling
- match sum {
- Sum::DuplicateVoteEvidence(d) => Self::DuplicateVoteEvidence(d),
- Sum::LightClientAttackEvidence(l) => Self::LightClientAttackEvidence(l),
+ match value.sum {
+ Some(sum) => sum.into(),
+ None => Self::None,
  }
  }
 }
 
 impl From<Sum> for EvidenceVariant {
- fn from(_: Sum) -> Self {
- unimplemented!() // Prost adds extra annotations on top of Sum that are not used.
+ fn from(value: Sum) -> Self {
+ match value {
+ Sum::DuplicateVoteEvidence(d) => Self::DuplicateVoteEvidence(d),
+ Sum::LightClientAttackEvidence(l) => Self::LightClientAttackEvidence(l),
+ }
  }
 }
 
 impl From<EvidenceVariant> for Sum {
- fn from(_: EvidenceVariant) -> Self {
- unimplemented!() // Prost adds extra annotations on top of Sum that are not used.
+ fn from(value: EvidenceVariant) -> Self {
+ match value {
+ // This should never be called - should be handled instead in the
+ // `impl From<EvidenceVariant> for Evidence` above.
+ EvidenceVariant::None => {
+ panic!("non-existent evidence cannot be converted into its protobuf representation")
+ }
+ EvidenceVariant::DuplicateVoteEvidence(d) => Self::DuplicateVoteEvidence(d),
+ EvidenceVariant::LightClientAttackEvidence(l) => Self::LightClientAttackEvidence(l),
+ }
+ }
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ // Minimally reproduce https://github.com/informalsystems/tendermint-rs/issues/782
+ #[test]
+ fn empty_evidence() {
+ let ev = Evidence { sum: None };
+ let ev_json = serde_json::to_string(&ev).unwrap();
+ let ev_deserialized = serde_json::from_str::<Evidence>(&ev_json).unwrap();
+ assert_eq!(ev, ev_deserialized);
  }
 }