Reject transactions with no provides tags. (#3416)

substrate/core/transaction-pool/graph/src/error.rs

@@ -30,6 +30,12 @@ pub enum Error {
 	/// Transaction is invalid.
 	#[display(fmt="Invalid Transaction. Error Code: {}", _0)]
 	InvalidTransaction(i8),
+	/// The transaction validity returned no "provides" tag.
+	///
+	/// Such transactions are not accepted to the pool, since we use those tags
+	/// to define identity of transactions (occupance of the same "slot").
+	#[display(fmt="The transaction does not provide any tags, so the pool can't identify it.")]
+	NoTagsProvided,
 	/// The transaction is temporarily banned.
 	#[display(fmt="Temporarily Banned")]
 	TemporarilyBanned,

substrate/core/transaction-pool/graph/src/pool.rs

@@ -129,7 +129,9 @@ impl<B: ChainApi> Pool<B> {
 				}
 
 				match self.api.validate_transaction(at, xt.clone())? {
-					TransactionValidity::Valid(validity) => {
+					TransactionValidity::Valid(validity) => if validity.provides.is_empty() {
+						Err(error::Error::NoTagsProvided.into())
+					} else {
 						Ok(base::Transaction {
 							data: xt,
 							bytes
@@ -458,6 +460,8 @@ mod tests {
 	use assert_matches::assert_matches;
 	use crate::watcher;
 
+	const INVALID_NONCE: u64 = 254;
+
 	#[derive(Debug, Default)]
 	struct TestApi {
 		delay: Mutex<Option<std::sync::mpsc::Receiver<()>>>,
@@ -490,7 +494,7 @@ mod tests {
 				Ok(TransactionValidity::Valid(ValidTransaction {
 					priority: 4,
 					requires: if nonce > block_number { vec![vec![nonce as u8 - 1]] } else { vec![] },
-					provides: vec![vec![nonce as u8]],
+					provides: if nonce == INVALID_NONCE { vec![] } else { vec![vec![nonce as u8]] },
 					longevity: 3,
 					propagate: true,
 				}))
@@ -723,6 +727,24 @@ mod tests {
 		assert_eq!(pool.status().future, 0);
 	}
 
+	#[test]
+	fn should_reject_transactions_with_no_provides() {
+		// given
+		let pool = pool();
+
+		// when
+		let err = pool.submit_one(&BlockId::Number(0), uxt(Transfer {
+			from: AccountId::from_h256(H256::from_low_u64_be(1)),
+			to: AccountId::from_h256(H256::from_low_u64_be(2)),
+			amount: 5,
+			nonce: INVALID_NONCE,
+		})).unwrap_err();
+
+		// then
+		assert_eq!(pool.status().ready, 0);
+		assert_eq!(pool.status().future, 0);
+		assert_matches!(err, error::Error::NoTagsProvided);
+	}
 
 	mod listener {
 		use super::*;