funds-manager: execution-client: Add quote execution helpers

funds-manager/funds-manager-server/src/custody_client/hot_wallets.rs

@@ -16,11 +16,11 @@ use rand::thread_rng;
 use tracing::info;
 use uuid::Uuid;
 
-use super::{CustodyClient, ERC20};
+use super::CustodyClient;
 use crate::{
     custody_client::DepositWithdrawSource,
     error::FundsManagerError,
-    helpers::{create_secrets_manager_entry_with_description, get_secret},
+    helpers::{create_secrets_manager_entry_with_description, get_secret, ERC20},
 };
 
 impl CustodyClient {
@@ -109,6 +109,7 @@ impl CustodyClient {
         Ok(())
     }
 
+    /// Transfer funds from a vault to a hot wallet
     pub async fn transfer_from_vault_to_hot_wallet(
         &self,
         vault: &str,

funds-manager/funds-manager-server/src/custody_client/mod.rs

@@ -1,5 +1,4 @@
 //! Manages the custody backend for the funds manager
-#![allow(missing_docs)]
 pub mod deposit;
 pub mod gas_wallets;
 mod hot_wallets;
@@ -8,7 +7,6 @@ pub mod withdraw;
 
 use aws_config::SdkConfig as AwsConfig;
 use ethers::middleware::SignerMiddleware;
-use ethers::prelude::abigen;
 use ethers::providers::{Http, Middleware, Provider};
 use ethers::signers::{LocalWallet, Signer};
 use ethers::types::{Address, TransactionReceipt, TransactionRequest};
@@ -26,16 +24,7 @@ use tracing::info;
 
 use crate::db::{DbConn, DbPool};
 use crate::error::FundsManagerError;
-
-abigen!(
-    ERC20,
-    r#"[
-        function balanceOf(address account) external view returns (uint256)
-        function transfer(address recipient, uint256 amount) external returns (bool)
-        function symbol() external view returns (string memory)
-        function decimals() external view returns (uint8)
-    ]"#
-);
+use crate::helpers::ERC20;
 
 /// The source of a deposit
 #[derive(Clone, Copy)]

funds-manager/funds-manager-server/src/custody_client/withdraw.rs

@@ -1,3 +1,4 @@
+//! Withdrawal methods for custodied funds
 use std::str::FromStr;
 
 use crate::{error::FundsManagerError, helpers::get_secret};

funds-manager/funds-manager-server/src/execution_client/error.rs

@@ -5,13 +5,21 @@ use std::fmt::Display;
 /// An error returned by the execution client
 #[derive(Debug, Clone)]
 pub enum ExecutionClientError {
+    /// An error interacting with Arbitrum
+    Arbitrum(String),
     /// An error returned by the execution client
     Http(String),
     /// An error parsing a value
     Parse(String),
 }
 
 impl ExecutionClientError {
+    /// Create a new arbitrum error
+    #[allow(clippy::needless_pass_by_value)]
+    pub fn arbitrum<T: ToString>(e: T) -> Self {
+        ExecutionClientError::Arbitrum(e.to_string())
+    }
+
     /// Create a new http error
     #[allow(clippy::needless_pass_by_value)]
     pub fn http<T: ToString>(e: T) -> Self {
@@ -28,6 +36,7 @@ impl ExecutionClientError {
 impl Display for ExecutionClientError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let msg = match self {
+            ExecutionClientError::Arbitrum(e) => format!("Arbitrum error: {e}"),
             ExecutionClientError::Http(e) => format!("HTTP error: {e}"),
             ExecutionClientError::Parse(e) => format!("Parse error: {e}"),
         };

funds-manager/funds-manager-server/src/execution_client/mod.rs

@@ -2,9 +2,15 @@
 //! API
 pub mod error;
 pub mod quotes;
+pub mod swap;
 
 use std::sync::Arc;
 
+use ethers::{
+    middleware::SignerMiddleware,
+    providers::{Http, Provider},
+    signers::LocalWallet,
+};
 use reqwest::{Client, Url};
 use serde::Deserialize;
 
@@ -22,12 +28,25 @@ pub struct ExecutionClient {
     base_url: String,
     /// The underlying HTTP client
     http_client: Arc<Client>,
+    /// The RPC provider
+    rpc_provider: Arc<Provider<Http>>,
 }
 
 impl ExecutionClient {
     /// Create a new client
-    pub fn new(api_key: String, base_url: String) -> Self {
-        Self { api_key, base_url, http_client: Arc::new(Client::new()) }
+    pub fn new(
+        api_key: String,
+        base_url: String,
+        rpc_url: String,
+    ) -> Result<Self, ExecutionClientError> {
+        let provider =
+            Provider::<Http>::try_from(&rpc_url).map_err(ExecutionClientError::arbitrum)?;
+        Ok(Self {
+            api_key,
+            base_url,
+            http_client: Arc::new(Client::new()),
+            rpc_provider: Arc::new(provider),
+        })
     }
 
     /// Get a full URL for a given endpoint
@@ -61,4 +80,12 @@ impl ExecutionClient {
             .await
             .map_err(ExecutionClientError::http)
     }
+
+    /// Get an instance of a signer middleware with the http provider attached
+    fn get_signer(
+        &self,
+        wallet: LocalWallet,
+    ) -> SignerMiddleware<Arc<Provider<Http>>, LocalWallet> {
+        SignerMiddleware::new(self.rpc_provider.clone(), wallet)
+    }
 }

funds-manager/funds-manager-server/src/execution_client/quotes.rs

@@ -1,6 +1,11 @@
 //! Client methods for fetching quotes and prices from the execution venue
 
-use serde::Deserialize;
+use ethers::types::{Address, Bytes, U256};
+use serde::{Deserialize, Serialize};
+
+use crate::helpers::{
+    address_string_serialization, bytes_string_serialization, u256_string_serialization,
+};
 
 use super::{error::ExecutionClientError, ExecutionClient};
 
@@ -26,21 +31,34 @@ pub struct PriceResponse {
 }
 
 /// The subset of the quote response forwarded to consumers of this client
-#[derive(Debug, Deserialize)]
+#[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct ExecutionQuote {
+    /// The token address we're buying
+    #[serde(with = "address_string_serialization")]
+    pub buy_token_address: Address,
+    /// The token address we're selling
+    #[serde(with = "address_string_serialization")]
+    pub sell_token_address: Address,
+    /// The amount of tokens to sell
+    pub sell_amount: String,
     /// The quoted price
     pub price: String,
     /// The submitting address
-    pub from: String,
+    #[serde(with = "address_string_serialization")]
+    pub from: Address,
     /// The 0x swap contract address
-    pub to: String,
+    #[serde(with = "address_string_serialization")]
+    pub to: Address,
     /// The calldata for the swap
-    pub data: String,
+    #[serde(with = "bytes_string_serialization")]
+    pub data: Bytes,
     /// The value of the tx; should be zero
-    pub value: String,
+    #[serde(with = "u256_string_serialization")]
+    pub value: U256,
     /// The gas price used in the swap
-    pub gas_price: String,
+    #[serde(with = "u256_string_serialization")]
+    pub gas_price: U256,
 }
 
 impl ExecutionClient {

funds-manager/funds-manager-server/src/execution_client/swap.rs

@@ -0,0 +1,74 @@
+//! Handlers for executing swaps
+
+use std::str::FromStr;
+use std::sync::Arc;
+
+use ethers::{
+    providers::Middleware,
+    signers::LocalWallet,
+    types::{Address, Eip1559TransactionRequest, TransactionReceipt, U256},
+};
+
+use crate::helpers::ERC20;
+
+use super::{error::ExecutionClientError, quotes::ExecutionQuote, ExecutionClient};
+
+impl ExecutionClient {
+    /// Execute a quoted swap
+    pub async fn execute_swap(
+        &self,
+        quote: ExecutionQuote,
+        wallet: LocalWallet,
+    ) -> Result<(), ExecutionClientError> {
+        // Approve the necessary ERC20 allowance
+        let amount = U256::from_str(&quote.sell_amount).map_err(ExecutionClientError::parse)?;
+        self.approve_erc20_allowance(quote.sell_token_address, quote.to, amount, &wallet).await?;
+
+        // Execute the swap
+        self.execute_swap_tx(quote, wallet).await.map(|_| ())
+    }
+
+    /// Approve an erc20 allowance
+    async fn approve_erc20_allowance(
+        &self,
+        token_address: Address,
+        spender: Address,
+        amount: U256,
+        wallet: &LocalWallet,
+    ) -> Result<TransactionReceipt, ExecutionClientError> {
+        let client = self.get_signer(wallet.clone());
+        let erc20 = ERC20::new(token_address, Arc::new(client));
+        let tx = erc20.approve(spender, amount);
+        let pending_tx = tx.send().await.map_err(ExecutionClientError::arbitrum)?;
+
+        pending_tx
+            .await
+            .map_err(ExecutionClientError::arbitrum)?
+            .ok_or_else(|| ExecutionClientError::arbitrum("Transaction failed"))
+    }
+
+    /// Execute a swap
+    async fn execute_swap_tx(
+        &self,
+        quote: ExecutionQuote,
+        wallet: LocalWallet,
+    ) -> Result<TransactionReceipt, ExecutionClientError> {
+        let client = self.get_signer(wallet.clone());
+        let tx = Eip1559TransactionRequest::new()
+            .to(quote.to)
+            .from(quote.from)
+            .value(quote.value)
+            .gas(quote.gas_price)
+            .data(quote.data);
+
+        // Send the transaction
+        let pending_tx = client
+            .send_transaction(tx, None /* block */)
+            .await
+            .map_err(ExecutionClientError::arbitrum)?;
+        pending_tx
+            .await
+            .map_err(ExecutionClientError::arbitrum)?
+            .ok_or_else(|| ExecutionClientError::arbitrum("Transaction failed"))
+    }
+}