feat(validations): set a maximum stake amount per validator and stake…

… transaction

config/src/defaults.rs

@@ -498,6 +498,9 @@ pub const PSEUDO_CONSENSUS_CONSTANTS_WIP0027_COLLATERAL_AGE: u32 = 13440;
 /// Maximum weight units that a block can devote to `StakeTransaction`s.
 pub const PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_BLOCK_WEIGHT: u32 = 10_000_000;
 
+/// Maximum amount of nanoWits that a `StakeTransaction` can add (and can be staked on a single validator).
+pub const PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS: u64 = 10_000_000_000_000_000;
+
 /// Minimum amount of nanoWits that a `StakeTransaction` can add, and minimum amount that can be
 /// left in stake by an `UnstakeTransaction`.
 pub const PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS: u64 = 10_000_000_000_000;

data_structures/src/chain/mod.rs

@@ -3013,6 +3013,19 @@ impl TransactionsPool {
             })
     }
 
+    /// Remove stake transactions that would result in overstaking on a validator
+    pub fn remove_overstake_transactions(&mut self, transactions: Vec<Hash>) {
+        for st_tx_hash in transactions.iter() {
+            if let Some(st_tx) = self
+                .st_transactions
+                .get(st_tx_hash)
+                .map(|(_, st)| st.clone())
+            {
+                self.st_remove(&st_tx);
+            }
+        }
+    }
+
     /// Remove an unstake transaction from the pool.
     ///
     /// This should be used to remove transactions that got included in a consolidated block.

data_structures/src/error.rs

@@ -301,6 +301,12 @@ pub enum TransactionError {
         stake, min_stake
     )]
     StakeBelowMinimum { min_stake: u64, stake: u64 },
+    /// Stake amount above maximum
+    #[fail(
+        display = "The amount of coins in stake ({}) is more than the maximum allowed ({})",
+        stake, max_stake
+    )]
+    StakeAboveMaximum { max_stake: u64, stake: u64 },
     /// Unstaking more than the total staked
     #[fail(
         display = "Tried to unstake more coins than the current stake ({} > {})",

node/src/actors/chain_manager/mining.rs

@@ -18,6 +18,7 @@ use futures::future::{try_join_all, FutureExt};
 
 use witnet_config::defaults::{
     PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_BLOCK_WEIGHT,
+    PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_WIP0027_COLLATERAL_AGE,
 };
@@ -37,7 +38,11 @@ use witnet_data_structures::{
     proto::versioning::{ProtocolVersion, ProtocolVersion::*, VersionedHashable},
     radon_error::RadonError,
     radon_report::{RadonReport, ReportContext, TypeLike},
-    staking::{stake::totalize_stakes, stakes::QueryStakesKey},
+    staking::{
+        helpers::StakeKey,
+        stake::totalize_stakes,
+        stakes::{QueryStakesKey, StakesTracker},
+    },
     transaction::{
         CommitTransaction, CommitTransactionBody, DRTransactionBody, MintTransaction,
         RevealTransaction, RevealTransactionBody, StakeTransactionBody, TallyTransaction,
@@ -77,6 +82,8 @@ use crate::{
     signature_mngr,
 };
 
+const MAX_STAKE_NANOWITS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS;
+
 impl ChainManager {
     /// Try to mine a block
     pub fn try_mine_block(&mut self, ctx: &mut Context<Self>) -> Result<(), ChainManagerError> {
@@ -236,6 +243,7 @@ impl ChainManager {
                     tapi_version,
                     &active_wips,
                     Some(validator_count),
+                    &act.chain_state.stakes,
                 );
 
                 // Sign the block hash
@@ -920,6 +928,7 @@ pub fn build_block(
     tapi_signals: u32,
     active_wips: &ActiveWips,
     validator_count: Option<usize>,
+    stakes: &StakesTracker,
 ) -> (BlockHeader, BlockTransactions) {
     let validator_count = validator_count.unwrap_or(DEFAULT_VALIDATOR_COUNT_FOR_TESTS);
     let (transactions_pool, unspent_outputs_pool, dr_pool) = pools_ref;
@@ -1141,6 +1150,7 @@ pub fn build_block(
     let protocol_version = ProtocolVersion::from_epoch(epoch);
 
     if protocol_version > V1_7 {
+        let mut overstake_transactions = Vec::<Hash>::new();
         let mut included_validators = HashSet::<PublicKeyHash>::new();
         for st_tx in transactions_pool.st_iter() {
             let validator_pkh = st_tx.body.output.authorization.public_key.pkh();
@@ -1152,6 +1162,37 @@ pub fn build_block(
                 continue;
             }
 
+            // If a set of staking transactions is sent simultaneously to the transactions pool using a staking amount smaller
+            // than MAX_STAKE_NANOWITS they can all be accepted since they do not introduce overstaking yet. However, accepting
+            // all of them in subsequent blocks could violate the MAX_STAKE_NANOWITS rule. Thus we still need to check that we
+            // do not include all these staking transactions in a block so we do not produce an invalid block.
+            let stakes_key = QueryStakesKey::Key(StakeKey {
+                validator: st_tx.body.output.key.validator,
+                withdrawer: st_tx.body.output.key.withdrawer,
+            });
+            match stakes.query_stakes(stakes_key) {
+                Ok(stake_entry) => {
+                    // TODO: modify this to enable delegated staking with multiple withdrawer addresses on a single validator
+                    let staked_amount: u64 = stake_entry
+                        .first()
+                        .map(|stake| stake.value.coins)
+                        .unwrap()
+                        .into();
+                    if st_tx.body.output.value + staked_amount > MAX_STAKE_NANOWITS {
+                        overstake_transactions.push(st_tx.hash());
+                        continue;
+                    }
+                }
+                Err(_) => {
+                    // This should never happen since a staking transaction to a non-existing (validator, withdrawer) pair
+                    // with a value higher than MAX_STAKE_NANOWITS should not have been accepted in the transactions pool.
+                    if st_tx.body.output.value > MAX_STAKE_NANOWITS {
+                        overstake_transactions.push(st_tx.hash());
+                        continue;
+                    }
+                }
+            };
+
             let transaction_weight = st_tx.weight();
             let transaction_fee =
                 match st_transaction_fee(st_tx, &utxo_diff, epoch, epoch_constants) {
@@ -1188,6 +1229,8 @@ pub fn build_block(
 
             included_validators.insert(validator_pkh);
         }
+
+        transactions_pool.remove_overstake_transactions(overstake_transactions);
     } else {
         transactions_pool.clear_stake_transactions();
     }

validations/src/tests/mod.rs

@@ -7,6 +7,7 @@ use std::{
 use itertools::Itertools;
 
 use witnet_config::defaults::{
+    PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_POS_UNSTAKING_DELAY_SECONDS,
     PSEUDO_CONSENSUS_CONSTANTS_WIP0022_REWARD_COLLATERAL_RATIO,
@@ -57,6 +58,7 @@ mod witnessing;
 static ONE_WIT: u64 = 1_000_000_000;
 const MAX_VT_WEIGHT: u32 = 20_000;
 const MAX_DR_WEIGHT: u32 = 80_000;
+const MAX_STAKE_NANOWITS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS;
 const MIN_STAKE_NANOWITS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS;
 const UNSTAKING_DELAY_SECONDS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_UNSTAKING_DELAY_SECONDS;
 
@@ -9001,6 +9003,73 @@ fn st_below_min_stake() {
     );
 }
 
+#[test]
+fn st_above_max_stake() {
+    register_protocol_version(ProtocolVersion::V1_8, 10000, 10);
+
+    // Setup stakes tracker with a (validator, validator) pair
+    let (validator_pkh, withdrawer_pkh, stakes) =
+        setup_stakes_tracker(MAX_STAKE_NANOWITS, PRIV_KEY_1, PRIV_KEY_2);
+
+    let utxo_set = UnspentOutputsPool::default();
+    let block_number = 0;
+    let utxo_diff = UtxoDiff::new(&utxo_set, block_number);
+    let mut signatures_to_verify = vec![];
+    let vti = Input::new(
+        "2222222222222222222222222222222222222222222222222222222222222222:1"
+            .parse()
+            .unwrap(),
+    );
+
+    // The stake transaction will fail because its value is above MAX_STAKE_NANOWITS
+    let stake_output = StakeOutput {
+        value: MAX_STAKE_NANOWITS + 1,
+        ..Default::default()
+    };
+    let stake_tx_body = StakeTransactionBody::new(vec![vti], stake_output, None);
+    let stake_tx = StakeTransaction::new(stake_tx_body, vec![]);
+    let x = validate_stake_transaction(
+        &stake_tx,
+        &utxo_diff,
+        Epoch::from(10000 as u32),
+        EpochConstants::default(),
+        &mut signatures_to_verify,
+        &stakes,
+    );
+    assert_eq!(
+        x.unwrap_err().downcast::<TransactionError>().unwrap(),
+        TransactionError::StakeAboveMaximum {
+            max_stake: MAX_STAKE_NANOWITS,
+            stake: MAX_STAKE_NANOWITS + 1,
+        }
+    );
+
+    // The stake transaction will fail because the sum of its value and the amount which is
+    // already staked is above MAX_STAKE_NANOWITS
+    let stake_output = StakeOutput {
+        value: MIN_STAKE_NANOWITS,
+        key: StakeKey::from((validator_pkh, withdrawer_pkh)),
+        ..Default::default()
+    };
+    let stake_tx_body = StakeTransactionBody::new(vec![vti], stake_output, None);
+    let stake_tx = StakeTransaction::new(stake_tx_body, vec![]);
+    let x = validate_stake_transaction(
+        &stake_tx,
+        &utxo_diff,
+        Epoch::from(10000 as u32),
+        EpochConstants::default(),
+        &mut signatures_to_verify,
+        &stakes,
+    );
+    assert_eq!(
+        x.unwrap_err().downcast::<TransactionError>().unwrap(),
+        TransactionError::StakeAboveMaximum {
+            max_stake: MAX_STAKE_NANOWITS,
+            stake: MAX_STAKE_NANOWITS + MIN_STAKE_NANOWITS,
+        }
+    );
+}
+
 #[test]
 fn unstake_success() {
     // Setup stakes tracker with a (validator, validator) pair

validations/src/validations.rs

@@ -8,6 +8,7 @@ use std::{
 use itertools::Itertools;
 
 use witnet_config::defaults::{
+    PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS,
     PSEUDO_CONSENSUS_CONSTANTS_POS_UNSTAKING_DELAY_SECONDS,
     PSEUDO_CONSENSUS_CONSTANTS_WIP0022_REWARD_COLLATERAL_RATIO,
@@ -68,6 +69,7 @@ use crate::eligibility::{
 
 // TODO: move to a configuration
 const MAX_STAKE_BLOCK_WEIGHT: u32 = 10_000_000;
+const MAX_STAKE_NANOWITS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_MAX_STAKE_NANOWITS;
 const MIN_STAKE_NANOWITS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_MIN_STAKE_NANOWITS;
 const MAX_UNSTAKE_BLOCK_WEIGHT: u32 = 5_000;
 const UNSTAKING_DELAY_SECONDS: u64 = PSEUDO_CONSENSUS_CONSTANTS_POS_UNSTAKING_DELAY_SECONDS;
@@ -1346,6 +1348,37 @@ pub fn validate_stake_transaction<'a>(
         st_tx.body.output.key.withdrawer,
     )?;
 
+    // Check that the amount of coins to stake plus the alread staked amount is equal or smaller than the maximum allowed
+    let stakes_key = QueryStakesKey::Key(StakeKey {
+        validator: st_tx.body.output.key.validator,
+        withdrawer: st_tx.body.output.key.withdrawer,
+    });
+    match stakes.query_stakes(stakes_key) {
+        Ok(stake_entry) => {
+            // TODO: modify this to enable delegated staking with multiple withdrawer addresses on a single validator
+            let staked_amount: u64 = stake_entry
+                .first()
+                .map(|stake| stake.value.coins)
+                .unwrap()
+                .into();
+            if staked_amount + st_tx.body.output.value > MAX_STAKE_NANOWITS {
+                Err(TransactionError::StakeAboveMaximum {
+                    max_stake: MAX_STAKE_NANOWITS,
+                    stake: staked_amount + st_tx.body.output.value,
+                })?;
+            }
+        }
+        Err(_) => {
+            // Check that the amount of coins to stake is equal or smaller than the maximum allowed
+            if st_tx.body.output.value > MAX_STAKE_NANOWITS {
+                Err(TransactionError::StakeAboveMaximum {
+                    max_stake: MAX_STAKE_NANOWITS,
+                    stake: st_tx.body.output.value,
+                })?;
+            }
+        }
+    };
+
     validate_transaction_signature(
         &st_tx.signatures,
         &st_tx.body.inputs,