fix(applying): contemplate fee rules for genesis UTxOs (#332)

pallas-applying/docs/byron-validation-rules.md

@@ -29,7 +29,7 @@ Refer to the [Byron's ledger white paper](https://github.com/input-output-hk/car
 	- ***addrHash<sub>utxo</sub> : TxIn -> KeyHash*** takes a transaction input, extracts its associated transaction output from ***utxo***, extracts the address contained in it, and returns its hash. In other words, given ***utxo*** and transaction input ***i*** such that ***utxo(i) = (a, _)***, we have that ***addrHash<sub>utxo</sub>(i) := hash(a)***.
 - **Protocol Parameters**:
 	- ***pps ∈ PParams*** is the set of (Byron) protocol parameters, with the following associated functions:
-		- ***minFees : PParams x Tx → ℕ*** gives the minimum amount of fees that must be paid for the transaction as determined by the protocol parameters.
+		- ***minFees : PParams x Tx → ℕ*** gives the minimum amount of fees that must be paid for the transaction as determined by the protocol parameters. If ***tx*** spends only genesis UTxOs (i.e., only input UTxOs generated at the genesis of the ledger), then ***minFees(pps, tx) = 0***.
 		- ***maxTxSize : PParams → ℕ*** gives the (global) maximum transaction size.
 - ***Witnesses***:
 	- ***VKey*** is the set of verification keys (a.k.a. public keys).

pallas-applying/src/byron.rs

@@ -74,7 +74,11 @@ fn check_outs_have_lovelace(tx: &Tx) -> ValidationResult {
 
 fn check_fees(tx: &Tx, size: &u64, utxos: &UTxOs, prot_pps: &ByronProtParams) -> ValidationResult {
     let mut inputs_balance: u64 = 0;
+    let mut only_redeem_utxos: bool = true;
     for input in tx.inputs.iter() {
+        if !is_redeem_utxo(input, utxos) {
+            only_redeem_utxos = false;
+        }
         match utxos
             .get(&MultiEraInput::from_byron(input))
             .and_then(MultiEraOutput::as_byron)
@@ -83,6 +87,9 @@ fn check_fees(tx: &Tx, size: &u64, utxos: &UTxOs, prot_pps: &ByronProtParams) ->
             None => return Err(ValidationError::UnableToComputeFees),
         }
     }
+    if only_redeem_utxos {
+        Ok(())
+    } else {
         let mut outputs_balance: u64 = 0;
         for output in tx.outputs.iter() {
             outputs_balance += output.amount
@@ -90,9 +97,24 @@ fn check_fees(tx: &Tx, size: &u64, utxos: &UTxOs, prot_pps: &ByronProtParams) ->
         let total_balance: u64 = inputs_balance - outputs_balance;
         let min_fees: u64 = prot_pps.min_fees_const + prot_pps.min_fees_factor * size;
         if total_balance < min_fees {
-        return Err(ValidationError::FeesBelowMin);
+            Err(ValidationError::FeesBelowMin)
-    }
+        } else {
             Ok(())
+        }
+    }
+}
+
+fn is_redeem_utxo(input: &TxIn, utxos: &UTxOs) -> bool {
+    match find_tx_out(input, utxos) {
+        Ok(tx_out) => {
+            let address: ByronAddress = mk_byron_address(&tx_out.address);
+            match address.decode() {
+                Ok(addr_payload) => matches!(addr_payload.addrtype, AddrType::Redeem),
+                _ => false,
+            }
+        }
+        _ => false,
+    }
 }
 
 fn check_size(size: &u64, prot_pps: &ByronProtParams) -> ValidationResult {

pallas-applying/tests/byron.rs

@@ -27,13 +27,11 @@ mod byron_tests {
         pallas_codec::minicbor::decode::<MintedTxPayload>(&tx_cbor[..]).unwrap()
     }
 
-    fn build_utxo<'a>(tx: &Tx) -> UTxOs<'a> {
+    // Careful: this function assumes tx has exactly one input.
+    fn mk_utxo_for_single_input_tx<'a>(tx: &Tx, address_payload: String, amount: u64) -> UTxOs<'a> {
         let mut tx_ins: Vec<TxIn> = tx.inputs.clone().to_vec();
         assert_eq!(tx_ins.len(), 1, "Unexpected number of inputs.");
         let tx_in: TxIn = tx_ins.pop().unwrap();
-        let address_payload =
-            "83581cff66e7549ee0706abe5ce63ba325f792f2c1145d918baf563db2b457a101581e581cca3e553c9c63\
-            c5927480e7434620200eb3a162ef0b6cf6f671ba925100";
         let input_tx_out_addr: Address = match hex::decode(address_payload) {
             Ok(addr_bytes) => Address {
                 payload: TagWrap(ByteVec::from(addr_bytes)),
@@ -43,18 +41,47 @@ mod byron_tests {
         };
         let tx_out: TxOut = TxOut {
             address: input_tx_out_addr,
-            amount: 19999000000,
+            amount: amount,
         };
         let mut utxos: UTxOs = new_utxos();
         add_to_utxo(&mut utxos, tx_in, tx_out);
         utxos
     }
 
+    #[test]
+    fn successful_mainnet_tx_with_genesis_utxos() {
+        let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron2.tx"));
+        let mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron2.address")),
+            // The number of lovelace in this input is irrelevant, since no fees have to be paid
+            // for this transaction.
+            1,
+        );
+        let env: Environment = Environment {
+            prot_params: MultiEraProtParams::Byron(ByronProtParams {
+                min_fees_const: 155381,
+                min_fees_factor: 44,
+                max_tx_size: 4096,
+            }),
+            prot_magic: 764824073,
+        };
+        match mk_byron_tx_and_validate(&mtxp.transaction, &mtxp.witness, &utxos, &env) {
+            Ok(()) => (),
+            Err(err) => assert!(false, "Unexpected error ({:?}).", err),
+        }
+    }
+
     #[test]
     fn successful_mainnet_tx() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         let env: Environment = Environment {
             prot_params: MultiEraProtParams::Byron(ByronProtParams {
                 min_fees_const: 155381,
@@ -74,7 +101,11 @@ mod byron_tests {
     fn empty_ins() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mut mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         // Clear the set of inputs in the transaction.
         let mut tx: Tx = (*mtxp.transaction).clone();
         tx.inputs = MaybeIndefArray::Def(Vec::new());
@@ -106,7 +137,11 @@ mod byron_tests {
     fn empty_outs() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mut mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         // Clear the set of outputs in the transaction.
         let mut tx: Tx = (*mtxp.transaction).clone();
         tx.outputs = MaybeIndefArray::Def(Vec::new());
@@ -161,7 +196,11 @@ mod byron_tests {
     fn output_without_lovelace() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mut mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         // Remove lovelace from output.
         let mut tx: Tx = (*mtxp.transaction).clone();
         let altered_tx_out: TxOut = TxOut {
@@ -200,7 +239,11 @@ mod byron_tests {
     fn not_enough_fees() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         let env: Environment = Environment {
             prot_params: MultiEraProtParams::Byron(ByronProtParams {
                 min_fees_const: 1000,
@@ -223,7 +266,11 @@ mod byron_tests {
     fn tx_size_exceeds_max() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         let env: Environment = Environment {
             prot_params: MultiEraProtParams::Byron(ByronProtParams {
                 min_fees_const: 155381,
@@ -246,7 +293,11 @@ mod byron_tests {
     fn missing_witness() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mut mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         // Remove witness
         let new_witnesses: Witnesses = MaybeIndefArray::Def(Vec::new());
         let mut tx_buf: Vec<u8> = Vec::new();
@@ -278,7 +329,11 @@ mod byron_tests {
     fn wrong_signature() {
         let cbor_bytes: Vec<u8> = cbor_to_bytes(include_str!("../../test_data/byron1.tx"));
         let mut mtxp: MintedTxPayload = mainnet_tx_from_bytes_cbor(&cbor_bytes);
-        let utxos: UTxOs = build_utxo(&mtxp.transaction);
+        let utxos: UTxOs = mk_utxo_for_single_input_tx(
+            &mtxp.transaction,
+            String::from(include_str!("../../test_data/byron1.address")),
+            19999000000,
+        );
         // Modify signature in witness
         let new_wit: Twit = match mtxp.witness[0].clone() {
             Twit::PkWitness(CborWrap((pk, _))) => {

test_data/byron1.address

@@ -0,0 +1 @@
+83581cff66e7549ee0706abe5ce63ba325f792f2c1145d918baf563db2b457a101581e581cca3e553c9c63c5927480e7434620200eb3a162ef0b6cf6f671ba925100

test_data/byron2.address

@@ -0,0 +1 @@
+83581CDC7E4DD6A44886816DEC9A4B2021056A8FCAF500C09E316028F2985FA002

test_data/byron2.tx

@@ -0,0 +1 @@
+82839f8200d818582482582031eae73dd9b018a6bc2eb1b229b5497de563a81872d54516251cc8185f93288300ff9f8282d818584283581c29bb9c5f4e8d38a10117e700a9238238d6f528df04b998af83ecc424a101581e581cc9deb2c011989356a5dc96450244e7ed22bfb30fbfc3f5807237fc39001a97bf58b71a000f4240ffa0818202d81858658258204d99cc5ec6c1891a483157560771a114463d92a530df8fd64e03f68f571de9b75840f67993afa4ec3b897355593e77baaf754ecfba2bba96265b829d79e4f452c7d6a6f363d41dea6731bff7a14efcc900e08f94e92c326344e540064ddf99052806