Fees for substrate (#375)

Co-authored-by: shekohex <dev+github@shadykhalifa.me>
Co-authored-by: Salman Pathan <pathansalman555@gmail.com>
Co-authored-by: drewstone <drewstone329@gmail.com>

README.md

@@ -488,18 +488,20 @@ cargo test
 
 ### To run E2E tests
 
-First you will need [`protocol-substrate`](https://github.com/webb-tools/protocol-substrate) node, compiled locally (in release mode) and both the `protocol-substrate` and `relayer` project must be next to each other. The relayer must be compiled using `--features integration-tests,cli`.
+First you will need [`protocol-substrate`](https://github.com/webb-tools/protocol-substrate) and [`tangle`](https://github.com/webb-tools/tangle) nodes, compiled locally (in release mode) and both the `protocol-substrate` and `relayer` project must be next to each other. The relayer must be compiled using `--features integration-tests,cli`.
 
 Here is the basic setup you will need:
 
 1. Clone the Relayer repo `git clone https://github.com/webb-tools/relayer.git`
 2. Clone Protocol Substrate node `https://github.com/webb-tools/protocol-substrate.git`
 3. Then fetch the submodules for the node `cd protocol-substrate && git submodule update --init`
 4. While you are there, build the standalone node `cargo build --release -p webb-standalone-node`
-5. And then go back to the relayer `cd ../relayer`
-6. Run `cd tests && dvc pull`
-7. Run `yarn install` (in `tests` dir)
-8. `yarn test`
+5. Clone Tangle repo `https://github.com/webb-tools/tangle.git`
+6. Build tangle `cd tangle && cargo build --release --features integration-tests -p tangle-standalone`
+7. And then go back to the relayer `cd ../relayer`
+8. Run `cd tests && dvc pull`
+9. Run `yarn install` (in `tests` dir)
+10. `yarn test`
 
 ### Tips for E2E tests
 

crates/relayer-handler-utils/src/lib.rs

@@ -18,7 +18,7 @@
 use serde::{Deserialize, Deserializer, Serialize};
 use tokio::sync::mpsc;
 use webb::evm::ethers::abi::Address;
-use webb::evm::ethers::prelude::{ContractError, I256};
+use webb::evm::ethers::prelude::{ContractError, I256, U128};
 use webb::evm::ethers::providers::Middleware;
 use webb::evm::ethers::types::Bytes;
 use webb::evm::ethers::types::{H256, U256};
@@ -52,6 +52,24 @@ impl<'de> Deserialize<'de> for WebbI256 {
         Ok(WebbI256(i128_val))
     }
 }
+/// A wrapper type around [`i128`] that implements a correct way for [`Serialize`] and [`Deserialize`].
+///
+/// This supports the signed integer hex values that are not originally supported by the [`i128`] type.
+#[derive(Debug, Clone, Serialize)]
+#[serde(transparent)]
+pub struct WebbI128(pub i128);
+
+impl<'de> Deserialize<'de> for WebbI128 {
+    fn deserialize<D>(deserializer: D) -> Result<WebbI128, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let i128_str = String::deserialize(deserializer)?;
+        let value = i128::from_str_radix(&i128_str, 16)
+            .map_err(serde::de::Error::custom)?;
+        Ok(WebbI128(value))
+    }
+}
 
 /// Type of Command to use
 #[derive(Debug, Clone, Deserialize)]
@@ -170,8 +188,8 @@ type P = Vec<u8>; // Substrate raw proof bytes
 type R = Vec<[u8; 32]>; // Substrate roots format
 type E = [u8; 32]; // Substrate element type
 type I = AccountId32; // Substrate account identifier
-type B = u128; // Substrate balance type
-type A = i128; // Substrate signed amount type
+type B = U128; // Substrate balance type
+type A = WebbI128; // Substrate signed amount type
 type T = u32; // Substrate assetId
 
 /// The command type for Substrate mixer txes

crates/relayer-handlers/src/lib.rs

@@ -24,6 +24,7 @@ use std::sync::Arc;
 use futures::prelude::*;
 
 use axum::extract::ws::{Message, WebSocket};
+use axum::http::StatusCode;
 use axum::response::Response;
 use axum::Json;
 use axum_client_ip::InsecureClientIp;
@@ -36,9 +37,12 @@ use webb_relayer_handler_utils::{
     Command, CommandResponse, CommandStream, EvmCommandType,
     IpInformationResponse, SubstrateCommandType,
 };
-use webb_relayer_tx_relay::evm::fees::{get_fee_info, FeeInfo};
+use webb_relayer_tx_relay::evm::fees::{get_evm_fee_info, EvmFeeInfo};
 
 use webb_relayer_tx_relay::evm::vanchor::handle_vanchor_relay_tx;
+use webb_relayer_tx_relay::substrate::fees::{
+    get_substrate_fee_info, SubstrateFeeInfo,
+};
 use webb_relayer_tx_relay::substrate::mixer::handle_substrate_mixer_relay_tx;
 use webb_relayer_tx_relay::substrate::vanchor::handle_substrate_vanchor_relay_tx;
 use webb_relayer_utils::HandlerError;
@@ -201,13 +205,33 @@ pub async fn handle_cmd(
 /// * `vanchor` - Address of the smart contract
 /// * `gas_amount` - How much gas the transaction needs. Don't use U256 here because it
 ///                  gets parsed incorrectly.
-pub async fn handle_fee_info(
+pub async fn handle_evm_fee_info(
     State(ctx): State<Arc<RelayerContext>>,
     Path((chain_id, vanchor, gas_amount)): Path<(u64, Address, u64)>,
-) -> Result<Json<FeeInfo>, HandlerError> {
+) -> Result<Json<EvmFeeInfo>, HandlerError> {
     let chain_id = TypedChainId::from(chain_id);
     let gas_amount = U256::from(gas_amount);
-    Ok(get_fee_info(chain_id, vanchor, gas_amount, ctx.as_ref())
+    Ok(
+        get_evm_fee_info(chain_id, vanchor, gas_amount, ctx.as_ref())
+            .await
+            .map(Json)?,
+    )
+}
+
+/// Handler for fee estimation
+///
+/// # Arguments
+/// * `chain_id` - ID of the blockchain
+/// * `estimated_tx_fees` - Estimated transaction fees
+/// * `ctx` - RelayContext reference that holds the configuration
+pub async fn handle_substrate_fee_info(
+    State(ctx): State<Arc<RelayerContext>>,
+    Path((chain_id, estimated_tx_fees)): Path<(u64, u128)>,
+) -> Result<Json<SubstrateFeeInfo>, HandlerError> {
+    get_substrate_fee_info(chain_id, estimated_tx_fees.into(), ctx.as_ref())
         .await
-        .map(Json)?)
+        .map(Json)
+        .map_err(|e| {
+            HandlerError(StatusCode::INTERNAL_SERVER_ERROR, e.to_string())
+        })
 }

crates/tx-relay/Cargo.toml

@@ -27,6 +27,7 @@ native-tls = { workspace = true, optional = true }
 webb-proposals = { workspace = true }
 ethereum-types = { workspace = true }
 serde = { workspace = true }
+sp-core = { workspace = true }
 
 once_cell = "1.17.0"
 chrono = { version = "0.4.23", features = ["serde"] }

crates/tx-relay/src/evm/fees.rs

@@ -1,8 +1,10 @@
+use crate::{MAX_REFUND_USD, TRANSACTION_PROFIT_USD};
 use chrono::DateTime;
 use chrono::Duration;
 use chrono::Utc;
 use once_cell::sync::Lazy;
 use serde::Serialize;
+use std::cmp::min;
 use std::collections::HashMap;
 use std::ops::Add;
 use std::sync::{Arc, Mutex};
@@ -11,6 +13,8 @@ use webb::evm::contract::protocol_solidity::{
 };
 use webb::evm::ethers::middleware::gas_oracle::GasOracle;
 use webb::evm::ethers::prelude::U256;
+use webb::evm::ethers::providers::Middleware;
+use webb::evm::ethers::signers::Signer;
 use webb::evm::ethers::types::Address;
 use webb::evm::ethers::utils::{format_units, parse_units};
 use webb_chains_info::chain_info_by_chain_id;
@@ -19,22 +23,19 @@ use webb_proposals::TypedChainId;
 use webb_relayer_context::RelayerContext;
 use webb_relayer_utils::Result;
 
-/// Maximum refund amount per relay transaction in USD.
-const MAX_REFUND_USD: f64 = 5.;
 /// Amount of time for which a `FeeInfo` is valid after creation
 static FEE_CACHE_TIME: Lazy<Duration> = Lazy::new(|| Duration::minutes(1));
-/// Amount of profit that the relay should make with each transaction (in USD).
-const TRANSACTION_PROFIT_USD: f64 = 5.;
 
 /// Cache for previously generated fee info. Key consists of the VAnchor address and chain id.
 /// Entries are valid as long as `timestamp` is no older than `FEE_CACHE_TIME`.
-static FEE_INFO_CACHED: Lazy<Mutex<HashMap<(Address, TypedChainId), FeeInfo>>> =
-    Lazy::new(|| Mutex::new(HashMap::new()));
+static FEE_INFO_CACHED: Lazy<
+    Mutex<HashMap<(Address, TypedChainId), EvmFeeInfo>>,
+> = Lazy::new(|| Mutex::new(HashMap::new()));
 
 /// Return value of fee_info API call. Contains information about relay transaction fee and refunds.
 #[derive(Debug, Serialize, Clone)]
 #[serde(rename_all = "camelCase")]
-pub struct FeeInfo {
+pub struct EvmFeeInfo {
     /// Estimated fee for an average relay transaction, in `wrappedToken`. This is only for
     /// display to the user
     pub estimated_fee: U256,
@@ -49,6 +50,9 @@ pub struct FeeInfo {
     /// Price of the native token in USD, internally cached to recalculate estimated fee
     #[serde(skip)]
     native_token_price: f64,
+    /// Number of decimals of the native token, internally cached to recalculate max refund
+    #[serde(skip)]
+    native_token_decimals: u8,
     /// Price of the wrapped token in USD, internally cached to recalculate estimated fee
     #[serde(skip)]
     wrapped_token_price: f64,
@@ -61,12 +65,12 @@ pub struct FeeInfo {
 ///
 /// If fee info was recently requested, the cached value is used. Otherwise it is regenerated
 /// based on the current exchange rate and estimated gas price.
-pub async fn get_fee_info(
+pub async fn get_evm_fee_info(
     chain_id: TypedChainId,
     vanchor: Address,
     gas_amount: U256,
     ctx: &RelayerContext,
-) -> Result<FeeInfo> {
+) -> Result<EvmFeeInfo> {
     // Retrieve cached fee info item
     let fee_info_cached = {
         let mut lock =
@@ -89,6 +93,14 @@ pub async fn get_fee_info(
             fee_info.wrapped_token_price,
             fee_info.wrapped_token_decimals,
         )?;
+        // Recalculate max refund in case relayer balance changed.
+        fee_info.max_refund = max_refund(
+            chain_id,
+            fee_info.native_token_price,
+            fee_info.native_token_decimals,
+            ctx,
+        )
+        .await?;
         Ok(fee_info)
     } else {
         let fee_info =
@@ -109,7 +121,7 @@ async fn generate_fee_info(
     vanchor: Address,
     gas_amount: U256,
     ctx: &RelayerContext,
-) -> Result<FeeInfo> {
+) -> Result<EvmFeeInfo> {
     // Get token names
     let (native_token, native_token_decimals) =
         get_native_token_name_and_decimals(chain_id)?;
@@ -162,25 +174,44 @@ async fn generate_fee_info(
     )?
     .into();
 
-    // Calculate the maximum refund amount per relay transaction in `nativeToken`.
-    let max_refund = parse_units(
-        MAX_REFUND_USD / native_token_price,
-        u32::from(native_token_decimals),
-    )?
-    .into();
-
-    Ok(FeeInfo {
+    Ok(EvmFeeInfo {
         estimated_fee,
         gas_price,
         refund_exchange_rate,
-        max_refund,
+        max_refund: max_refund(
+            chain_id,
+            native_token_price,
+            native_token_decimals,
+            ctx,
+        )
+        .await?,
         timestamp: Utc::now(),
         native_token_price,
+        native_token_decimals,
         wrapped_token_price,
         wrapped_token_decimals,
     })
 }
 
+async fn max_refund(
+    chain_id: TypedChainId,
+    native_token_price: f64,
+    native_token_decimals: u8,
+    ctx: &RelayerContext,
+) -> Result<U256> {
+    let wallet = ctx.evm_wallet(chain_id.underlying_chain_id()).await?;
+    let provider = ctx.evm_provider(chain_id.underlying_chain_id()).await?;
+    let relayer_balance = provider.get_balance(wallet.address(), None).await?;
+    // Calculate the maximum refund amount per relay transaction in `nativeToken`.
+    // Ensuring that refund <= relayer balance
+    let max_refund = parse_units(
+        MAX_REFUND_USD / native_token_price,
+        u32::from(native_token_decimals),
+    )?
+    .into();
+    Ok(min(relayer_balance, max_refund))
+}
+
 /// Pull USD prices of base token from coingecko.com, and use this to calculate the transaction
 /// fee in `wrappedToken` wei. This fee includes a profit for the relay of `TRANSACTION_PROFIT_USD`.
 ///
@@ -265,7 +296,7 @@ fn get_native_token_name_and_decimals(
             },
         ),
         Substrate(id) => match id {
-            1080 => Ok(("tTNT", 18)),
+            1081 => Ok(("tTNT", 18)),
             _ => {
                 // During testing, we will use the tTNT token for all substrate chains.
                 if cfg!(debug_assertions) {

crates/tx-relay/src/evm/vanchor.rs

@@ -1,7 +1,8 @@
 use super::*;
-use crate::evm::fees::{get_fee_info, FeeInfo};
+use crate::evm::fees::{get_evm_fee_info, EvmFeeInfo};
 use crate::evm::handle_evm_tx;
 use ethereum_types::U256;
+use futures::TryFutureExt;
 use std::{collections::HashMap, sync::Arc};
 use webb::evm::ethers::utils::{format_units, parse_ether};
 use webb::evm::{
@@ -81,19 +82,6 @@ pub async fn handle_vanchor_relay_tx<'a>(
     })?;
     let _ = stream.send(Network(NetworkStatus::Connected)).await;
 
-    // ensure that relayer has enough balance for refund
-    let relayer_balance = provider
-        .get_balance(wallet.address(), None)
-        .await
-        .map_err(|e| {
-            Error(format!("Failed to retrieve relayer balance: {e}"))
-        })?;
-    if cmd.ext_data.refund > relayer_balance {
-        return Err(Error(
-            "Requested refund is higher than relayer balance".to_string(),
-        ));
-    }
-
     let client = Arc::new(SignerMiddleware::new(provider, wallet));
     let contract = VAnchorContract::new(cmd.id, client.clone());
 
@@ -142,6 +130,7 @@ pub async fn handle_vanchor_relay_tx<'a>(
         public_inputs,
         encryptions,
     );
+
     if !cmd.ext_data.refund.is_zero() {
         call = call.value(cmd.ext_data.refund);
     }
@@ -153,7 +142,7 @@ pub async fn handle_vanchor_relay_tx<'a>(
             })
         })?;
     let typed_chain_id = TypedChainId::Evm(chain.chain_id);
-    let fee_info = get_fee_info(
+    let fee_info = get_evm_fee_info(
         typed_chain_id,
         contract_config.common.address,
         gas_amount,
@@ -186,7 +175,8 @@ pub async fn handle_vanchor_relay_tx<'a>(
     if cmd.ext_data.fee < adjusted_fee + wrapped_amount {
         let msg = format!(
             "User sent a fee that is too low {} but expected {}",
-            cmd.ext_data.fee, fee_info.estimated_fee
+            cmd.ext_data.fee,
+            adjusted_fee + wrapped_amount
         );
         return Err(Error(msg));
     }
@@ -214,6 +204,11 @@ pub async fn handle_vanchor_relay_tx<'a>(
         .total_fee_earned
         .inc_by(cmd.ext_data.fee.as_u128() as f64);
 
+    let relayer_balance = client
+        .get_balance(client.signer().address(), None)
+        .unwrap_or_else(|_| U256::zero())
+        .await;
+
     metrics
         .account_balance_entry(typed_chain_id)
         .set(wei_to_gwei(relayer_balance));
@@ -222,7 +217,7 @@ pub async fn handle_vanchor_relay_tx<'a>(
 
 fn calculate_wrapped_refund_amount(
     refund: U256,
-    fee_info: &FeeInfo,
+    fee_info: &EvmFeeInfo,
 ) -> webb_relayer_utils::Result<U256> {
     let refund_exchange_rate: f32 =
         format_units(fee_info.refund_exchange_rate, "ether")?.parse()?;

crates/tx-relay/src/lib.rs

@@ -4,3 +4,8 @@ pub mod evm;
 /// Substrate Transactional Relayer.
 #[cfg(feature = "substrate")]
 pub mod substrate;
+
+/// Maximum refund amount per relay transaction in USD.
+const MAX_REFUND_USD: f64 = 5.;
+/// Amount of profit that the relay should make with each transaction (in USD).
+const TRANSACTION_PROFIT_USD: f64 = 5.;