From a8ba89fe2195232e7e860342617ddf5f6c6244c2 Mon Sep 17 00:00:00 2001
From: Stan Bondi <sdbondi@users.noreply.github.com>
Date: Fri, 1 Jul 2022 13:58:54 +0200
Subject: [PATCH] feat(core): validates non-contract utxos have no sidechain
 features (#4259)

Description
---
- adds simple validation rule to check that non-contract outputs do not contain sidechain features

Motivation and Context
---
Outputs that are not flagged with contract `OutputType`s should not contain `SideChainFeatures`

How Has This Been Tested?
---
Fail case unit test, happy case is tested by other tests
---
 .../core/src/validation/dan_validators/mod.rs | 38 ++++++++++++++++++-
 base_layer/core/src/validation/error.rs       | 11 +++++-
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/base_layer/core/src/validation/dan_validators/mod.rs b/base_layer/core/src/validation/dan_validators/mod.rs
index fbaed04b67..004e86c6e8 100644
--- a/base_layer/core/src/validation/dan_validators/mod.rs
+++ b/base_layer/core/src/validation/dan_validators/mod.rs
@@ -52,6 +52,8 @@ mod helpers;
 mod error;
 pub use error::DanLayerValidationError;
 
+use crate::transactions::transaction_components::TransactionOutput;
+
 #[cfg(test)]
 mod test_helpers;
 
@@ -80,10 +82,44 @@ impl<B: BlockchainBackend> MempoolTransactionValidation for TxDanLayerValidator<
                     validate_update_proposal_acceptance(&self.db, output)?
                 },
                 OutputType::ContractAmendment => validate_amendment(&self.db, output)?,
-                _ => continue,
+                _ => validate_no_sidechain_features(output)?,
             }
         }
 
         Ok(())
     }
 }
+
+fn validate_no_sidechain_features(output: &TransactionOutput) -> Result<(), ValidationError> {
+    match output.features.sidechain_features {
+        Some(ref features) => Err(ValidationError::NonContractOutputContainsSidechainFeatures {
+            output_type: output.features.output_type,
+            contract_id: features.contract_id,
+        }),
+        None => Ok(()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use tari_common_types::types::FixedHash;
+
+    use super::*;
+    use crate::transactions::{
+        test_helpers::{create_unblinded_coinbase, TestParams},
+        transaction_components::SideChainFeatures,
+        CryptoFactories,
+    };
+
+    #[test]
+    fn it_rejects_standard_output_type_with_sidechain_features() {
+        let mut utxo = create_unblinded_coinbase(&TestParams::new(), 1);
+        utxo.features.sidechain_features = Some(SideChainFeatures::builder(FixedHash::default()).finish());
+        let output = utxo.as_transaction_output(&CryptoFactories::default()).unwrap();
+        let err = validate_no_sidechain_features(&output).unwrap_err();
+        assert!(matches!(
+            err,
+            ValidationError::NonContractOutputContainsSidechainFeatures { .. }
+        ))
+    }
+}
diff --git a/base_layer/core/src/validation/error.rs b/base_layer/core/src/validation/error.rs
index 6ba293a229..1fbe87d21f 100644
--- a/base_layer/core/src/validation/error.rs
+++ b/base_layer/core/src/validation/error.rs
@@ -20,7 +20,7 @@
 // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 // USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-use tari_common_types::types::HashOutput;
+use tari_common_types::types::{FixedHash, HashOutput};
 use thiserror::Error;
 use tokio::task;
 
@@ -29,7 +29,7 @@ use crate::{
     chain_storage::ChainStorageError,
     covenants::CovenantError,
     proof_of_work::{monero_rx::MergeMineError, PowError},
-    transactions::transaction_components::TransactionError,
+    transactions::transaction_components::{OutputType, TransactionError},
     validation::dan_validators::DanLayerValidationError,
 };
 
@@ -119,6 +119,13 @@ pub enum ValidationError {
     ErroneousCoinbaseOutput,
     #[error("Digital Asset Network Error: {0}")]
     DanLayerError(#[from] DanLayerValidationError),
+    #[error(
+        "Output was flagged as a {output_type} but contained sidechain feature data with contract_id {contract_id}"
+    )]
+    NonContractOutputContainsSidechainFeatures {
+        output_type: OutputType,
+        contract_id: FixedHash,
+    },
 }
 
 // ChainStorageError has a ValidationError variant, so to prevent a cyclic dependency we use a string representation in