Merge #481

481: Min buy amount r=da-kami a=da-kami



Co-authored-by: Daniel Karzel <daniel@comit.network>

swap/Cargo.toml

@@ -40,7 +40,7 @@ proptest = "1"
 rand = "0.7"
 rand_chacha = "0.2"
 reqwest = { version = "0.11", features = [ "rustls-tls", "stream", "socks" ], default-features = false }
-rust_decimal = "1"
+rust_decimal = { version = "1", features = [ "serde-float" ] }
 rust_decimal_macros = "1"
 serde = { version = "1", features = [ "derive" ] }
 serde_cbor = "0.11"

swap/src/asb/command.rs

@@ -1,7 +1,5 @@
 use crate::bitcoin::Amount;
-use bitcoin::util::amount::ParseAmountError;
-use bitcoin::{Address, Denomination};
-use rust_decimal::Decimal;
+use bitcoin::Address;
 use std::path::PathBuf;
 use uuid::Uuid;
 
@@ -28,15 +26,6 @@ pub struct Arguments {
 pub enum Command {
     #[structopt(about = "Main command to run the ASB.")]
     Start {
-        #[structopt(long = "max-buy-btc", help = "The maximum amount of BTC the ASB is willing to buy.", default_value = "0.005", parse(try_from_str = parse_btc))]
-        max_buy: Amount,
-        #[structopt(
-            long = "ask-spread",
-            help = "The spread in percent that should be applied to the asking price.",
-            default_value = "0.02"
-        )]
-        ask_spread: Decimal,
-
         #[structopt(
             long = "resume-only",
             help = "For maintenance only. When set, no new swap requests will be accepted, but existing unfinished swaps will be resumed."
@@ -124,7 +113,3 @@ pub struct RecoverCommandParams {
     )]
     pub force: bool,
 }
-
-fn parse_btc(s: &str) -> Result<Amount, ParseAmountError> {
-    Amount::from_str_in(s, Denomination::Bitcoin)
-}

swap/src/asb/config.rs

@@ -1,10 +1,12 @@
 use crate::fs::{ensure_directory_exists, system_config_dir, system_data_dir};
 use crate::tor::{DEFAULT_CONTROL_PORT, DEFAULT_SOCKS5_PORT};
-use anyhow::{Context, Result};
+use anyhow::{bail, Context, Result};
 use config::ConfigError;
 use dialoguer::theme::ColorfulTheme;
 use dialoguer::Input;
 use libp2p::core::Multiaddr;
+use rust_decimal::prelude::FromPrimitive;
+use rust_decimal::Decimal;
 use serde::{Deserialize, Serialize};
 use std::ffi::OsStr;
 use std::fs;
@@ -18,6 +20,10 @@ const DEFAULT_ELECTRUM_RPC_URL: &str = "ssl://electrum.blockstream.info:60002";
 const DEFAULT_MONERO_WALLET_RPC_TESTNET_URL: &str = "http://127.0.0.1:38083/json_rpc";
 const DEFAULT_BITCOIN_CONFIRMATION_TARGET: usize = 3;
 
+const DEFAULT_MIN_BUY_AMOUNT: f64 = 0.002f64;
+const DEFAULT_MAX_BUY_AMOUNT: f64 = 0.02f64;
+const DEFAULT_SPREAD: f64 = 0.02f64;
+
 #[derive(Clone, Debug, serde::Serialize, serde::Deserialize, PartialEq)]
 pub struct Config {
     pub data: Data,
@@ -25,6 +31,7 @@ pub struct Config {
     pub bitcoin: Bitcoin,
     pub monero: Monero,
     pub tor: TorConf,
+    pub maker: Maker,
 }
 
 impl Config {
@@ -72,6 +79,16 @@ pub struct TorConf {
     pub socks5_port: u16,
 }
 
+#[derive(Clone, Debug, Deserialize, PartialEq, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct Maker {
+    #[serde(with = "::bitcoin::util::amount::serde::as_btc")]
+    pub min_buy_btc: bitcoin::Amount,
+    #[serde(with = "::bitcoin::util::amount::serde::as_btc")]
+    pub max_buy_btc: bitcoin::Amount,
+    pub ask_spread: Decimal,
+}
+
 impl Default for TorConf {
     fn default() -> Self {
         Self {
@@ -123,10 +140,11 @@ where
     F: Fn() -> Result<Config>,
 {
     info!("Config file not found, running initial setup...");
-    ensure_directory_exists(config_path.as_path())?;
     let initial_config = config_file()?;
 
     let toml = toml::to_string(&initial_config)?;
+
+    ensure_directory_exists(config_path.as_path())?;
     fs::write(&config_path, toml)?;
 
     info!(
@@ -185,6 +203,27 @@ pub fn query_user_for_initial_testnet_config() -> Result<Config> {
         .default(DEFAULT_SOCKS5_PORT.to_owned())
         .interact_text()?;
 
+    let min_buy = Input::with_theme(&ColorfulTheme::default())
+        .with_prompt("Enter minimum Bitcoin amount you are willing to accept per swap or hit enter to use default.")
+        .default(DEFAULT_MIN_BUY_AMOUNT)
+        .interact_text()?;
+    let min_buy = bitcoin::Amount::from_btc(min_buy)?;
+
+    let max_buy = Input::with_theme(&ColorfulTheme::default())
+        .with_prompt("Enter maximum Bitcoin amount you are willing to accept per swap or hit enter to use default.")
+        .default(DEFAULT_MAX_BUY_AMOUNT)
+        .interact_text()?;
+    let max_buy = bitcoin::Amount::from_btc(max_buy)?;
+
+    let ask_spread = Input::with_theme(&ColorfulTheme::default())
+        .with_prompt("Enter spread (in percent; value between 0.x and 1.0) to be used on top of the market rate or hit enter to use default.")
+        .default(DEFAULT_SPREAD)
+        .interact_text()?;
+    if !(0.0..=1.0).contains(&ask_spread) {
+        bail!(format!("Invalid spread {}. For the spread value floating point number in interval [0..1] are allowed.", ask_spread))
+    }
+    let ask_spread = Decimal::from_f64(ask_spread).context("Unable to parse spread")?;
+
     println!();
 
     Ok(Config {
@@ -203,6 +242,11 @@ pub fn query_user_for_initial_testnet_config() -> Result<Config> {
             control_port: tor_control_port,
             socks5_port: tor_socks5_port,
         },
+        maker: Maker {
+            min_buy_btc: min_buy,
+            max_buy_btc: max_buy,
+            ask_spread,
+        },
     })
 }
 
@@ -236,6 +280,11 @@ mod tests {
                 wallet_rpc_url: Url::from_str(DEFAULT_MONERO_WALLET_RPC_TESTNET_URL).unwrap(),
             },
             tor: Default::default(),
+            maker: Maker {
+                min_buy_btc: bitcoin::Amount::from_btc(DEFAULT_MIN_BUY_AMOUNT).unwrap(),
+                max_buy_btc: bitcoin::Amount::from_btc(DEFAULT_MAX_BUY_AMOUNT).unwrap(),
+                ask_spread: Decimal::from_f64(DEFAULT_SPREAD).unwrap(),
+            },
         };
 
         initial_setup(config_path.clone(), || Ok(expected.clone())).unwrap();

swap/src/bin/asb.rs

@@ -79,11 +79,7 @@ async fn main() -> Result<()> {
     let env_config = env::Testnet::get_config();
 
     match opt.cmd {
-        Command::Start {
-            max_buy,
-            ask_spread,
-            resume_only,
-        } => {
+        Command::Start { resume_only } => {
             let bitcoin_wallet = init_bitcoin_wallet(&config, &seed, env_config).await?;
             let monero_wallet = init_monero_wallet(&config, env_config).await?;
 
@@ -122,12 +118,13 @@ async fn main() -> Result<()> {
 
             let current_balance = monero_wallet.get_balance().await?;
             let lock_fee = monero_wallet.static_tx_fee_estimate();
-            let kraken_rate = KrakenRate::new(ask_spread, kraken_price_updates);
+            let kraken_rate = KrakenRate::new(config.maker.ask_spread, kraken_price_updates);
             let mut swarm = swarm::alice(
                 &seed,
                 current_balance,
                 lock_fee,
-                max_buy,
+                config.maker.min_buy_btc,
+                config.maker.max_buy_btc,
                 kraken_rate.clone(),
                 resume_only,
             )?;
@@ -144,7 +141,8 @@ async fn main() -> Result<()> {
                 Arc::new(monero_wallet),
                 Arc::new(db),
                 kraken_rate,
-                max_buy,
+                config.maker.min_buy_btc,
+                config.maker.max_buy_btc,
             )
             .unwrap();
 

swap/src/bin/swap.rs

@@ -20,7 +20,7 @@ use std::path::PathBuf;
 use std::sync::Arc;
 use std::time::Duration;
 use structopt::StructOpt;
-use swap::bitcoin::{Amount, TxLock};
+use swap::bitcoin::TxLock;
 use swap::cli::command::{Arguments, Command, MoneroParams};
 use swap::database::Database;
 use swap::env::{Config, GetConfig};
@@ -94,23 +94,19 @@ async fn main() -> Result<()> {
                 EventLoop::new(swap_id, swarm, alice_peer_id, bitcoin_wallet.clone())?;
             let event_loop = tokio::spawn(event_loop.run());
 
-            let send_bitcoin = determine_btc_to_swap(
+            let max_givable = || bitcoin_wallet.max_giveable(TxLock::script_size());
+            let (send_bitcoin, fees) = determine_btc_to_swap(
                 event_loop_handle.request_quote(),
-                bitcoin_wallet.balance(),
+                max_givable().await?,
                 bitcoin_wallet.new_address(),
-                async {
-                    while bitcoin_wallet.balance().await? == Amount::ZERO {
-                        bitcoin_wallet.sync().await?;
-
-                        tokio::time::sleep(Duration::from_secs(1)).await;
-                    }
-
-                    bitcoin_wallet.balance().await
-                },
-                bitcoin_wallet.max_giveable(TxLock::script_size()),
+                || bitcoin_wallet.balance(),
+                max_givable,
+                || bitcoin_wallet.sync(),
             )
             .await?;
 
+            info!("Swapping {} with {} fees", send_bitcoin, fees);
+
             db.insert_peer_id(swap_id, alice_peer_id).await?;
 
             let swap = Swap::new(
@@ -332,51 +328,83 @@ async fn init_monero_wallet(
     Ok((monero_wallet, monero_wallet_rpc_process))
 }
 
-async fn determine_btc_to_swap(
-    request_quote: impl Future<Output = Result<BidQuote>>,
-    initial_balance: impl Future<Output = Result<bitcoin::Amount>>,
+async fn determine_btc_to_swap<FB, TB, FMG, TMG, FS, TS>(
+    bid_quote: impl Future<Output = Result<BidQuote>>,
+    mut current_maximum_giveable: bitcoin::Amount,
     get_new_address: impl Future<Output = Result<bitcoin::Address>>,
-    wait_for_deposit: impl Future<Output = Result<bitcoin::Amount>>,
-    max_giveable: impl Future<Output = Result<bitcoin::Amount>>,
-) -> Result<bitcoin::Amount> {
+    balance: FB,
+    max_giveable: FMG,
+    sync: FS,
+) -> Result<(bitcoin::Amount, bitcoin::Amount)>
+where
+    TB: Future<Output = Result<bitcoin::Amount>>,
+    FB: Fn() -> TB,
+    TMG: Future<Output = Result<bitcoin::Amount>>,
+    FMG: Fn() -> TMG,
+    TS: Future<Output = Result<()>>,
+    FS: Fn() -> TS,
+{
     debug!("Requesting quote");
-
-    let bid_quote = request_quote.await?;
-
+    let bid_quote = bid_quote.await?;
     info!("Received quote: 1 XMR ~ {}", bid_quote.price);
 
-    // TODO: Also wait for more funds if balance < dust
-    let initial_balance = initial_balance.await?;
+    let max_giveable = if current_maximum_giveable == bitcoin::Amount::ZERO
+        || current_maximum_giveable < bid_quote.min_quantity
+    {
+        let deposit_address = get_new_address.await?;
+        let minimum_amount = bid_quote.min_quantity;
+        let maximum_amount = bid_quote.max_quantity;
 
-    let balance = if initial_balance == Amount::ZERO {
         info!(
-            "Please deposit the BTC you want to swap to {} (max {})",
-            get_new_address.await?,
-            bid_quote.max_quantity
+            %deposit_address,
+            %current_maximum_giveable,
+            %minimum_amount,
+            %maximum_amount,
+            "Please deposit BTC you want to swap to",
         );
 
-        let new_balance = wait_for_deposit
-            .await
-            .context("Failed to wait for Bitcoin deposit")?;
+        loop {
+            sync().await?;
 
-        info!("Received {}", new_balance);
-        new_balance
+            let new_max_givable = max_giveable().await?;
+
+            if new_max_givable != current_maximum_giveable {
+                current_maximum_giveable = new_max_givable;
+
+                let new_balance = balance().await?;
+                tracing::info!(
+                    %new_balance,
+                    %current_maximum_giveable,
+                    "Received BTC",
+                );
+
+                if current_maximum_giveable >= bid_quote.min_quantity {
+                    break;
+                } else {
+                    tracing::info!(
+                        %minimum_amount,
+                        %deposit_address,
+                        "Please deposit more, not enough BTC to trigger swap with",
+                    );
+                }
+            }
+
+            tokio::time::sleep(Duration::from_secs(1)).await;
+        }
+
+        current_maximum_giveable
     } else {
-        info!("Found {} in wallet", initial_balance);
-        initial_balance
+        current_maximum_giveable
     };
 
-    let max_giveable = max_giveable
-        .await
-        .context("Failed to compute max 'giveable' Bitcoin amount")?;
+    let balance = balance().await?;
     let fees = balance - max_giveable;
 
     let max_accepted = bid_quote.max_quantity;
 
     let btc_swap_amount = min(max_giveable, max_accepted);
-    info!("Swapping {} with {} fees", btc_swap_amount, fees);
 
-    Ok(btc_swap_amount)
+    Ok((btc_swap_amount, fees))
 }
 
 #[cfg(test)]
@@ -390,74 +418,162 @@ mod tests {
     async fn given_no_balance_and_transfers_less_than_max_swaps_max_giveable() {
         let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
 
-        let amount = determine_btc_to_swap(
+        let (amount, fees) = determine_btc_to_swap(
             async { Ok(quote_with_max(0.01)) },
-            async { Ok(Amount::ZERO) },
+            Amount::ZERO,
             get_dummy_address(),
-            async { Ok(Amount::from_btc(0.0001)?) },
-            async { Ok(Amount::from_btc(0.00009)?) },
+            || async { Ok(Amount::from_btc(0.001)?) },
+            || async { Ok(Amount::from_btc(0.0009)?) },
+            || async { Ok(()) },
         )
         .await
         .unwrap();
 
-        assert_eq!(amount, Amount::from_btc(0.00009).unwrap())
+        let expected_amount = Amount::from_btc(0.0009).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
     }
 
     #[tokio::test]
     async fn given_no_balance_and_transfers_more_then_swaps_max_quantity_from_quote() {
         let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
 
-        let amount = determine_btc_to_swap(
+        let (amount, fees) = determine_btc_to_swap(
             async { Ok(quote_with_max(0.01)) },
-            async { Ok(Amount::ZERO) },
+            Amount::ZERO,
             get_dummy_address(),
-            async { Ok(Amount::from_btc(0.1)?) },
-            async { Ok(Amount::from_btc(0.09)?) },
+            || async { Ok(Amount::from_btc(0.1001)?) },
+            || async { Ok(Amount::from_btc(0.1)?) },
+            || async { Ok(()) },
         )
         .await
         .unwrap();
 
-        assert_eq!(amount, Amount::from_btc(0.01).unwrap())
+        let expected_amount = Amount::from_btc(0.01).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
     }
 
     #[tokio::test]
     async fn given_initial_balance_below_max_quantity_swaps_max_givable() {
         let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
 
-        let amount = determine_btc_to_swap(
+        let (amount, fees) = determine_btc_to_swap(
             async { Ok(quote_with_max(0.01)) },
-            async { Ok(Amount::from_btc(0.005)?) },
+            Amount::from_btc(0.0049).unwrap(),
             async { panic!("should not request new address when initial balance is > 0") },
-            async { panic!("should not wait for deposit when initial balance > 0") },
-            async { Ok(Amount::from_btc(0.0049)?) },
+            || async { Ok(Amount::from_btc(0.005)?) },
+            || async { panic!("should not wait for deposit when initial balance > 0") },
+            || async { Ok(()) },
         )
         .await
         .unwrap();
 
-        assert_eq!(amount, Amount::from_btc(0.0049).unwrap())
+        let expected_amount = Amount::from_btc(0.0049).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
     }
 
     #[tokio::test]
     async fn given_initial_balance_above_max_quantity_swaps_max_quantity() {
         let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
 
-        let amount = determine_btc_to_swap(
+        let (amount, fees) = determine_btc_to_swap(
             async { Ok(quote_with_max(0.01)) },
-            async { Ok(Amount::from_btc(0.1)?) },
+            Amount::from_btc(0.1).unwrap(),
             async { panic!("should not request new address when initial balance is > 0") },
-            async { panic!("should not wait for deposit when initial balance > 0") },
-            async { Ok(Amount::from_btc(0.09)?) },
+            || async { Ok(Amount::from_btc(0.1001)?) },
+            || async { panic!("should not wait for deposit when initial balance > 0") },
+            || async { Ok(()) },
         )
         .await
         .unwrap();
 
-        assert_eq!(amount, Amount::from_btc(0.01).unwrap())
+        let expected_amount = Amount::from_btc(0.01).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
+    }
+
+    #[tokio::test]
+    async fn given_no_initial_balance_then_min_wait_for_sufficient_deposit() {
+        let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
+
+        let (amount, fees) = determine_btc_to_swap(
+            async { Ok(quote_with_min(0.01)) },
+            Amount::ZERO,
+            get_dummy_address(),
+            || async { Ok(Amount::from_btc(0.0101)?) },
+            || async { Ok(Amount::from_btc(0.01)?) },
+            || async { Ok(()) },
+        )
+        .await
+        .unwrap();
+
+        let expected_amount = Amount::from_btc(0.01).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
+    }
+
+    #[tokio::test]
+    async fn given_balance_less_then_min_wait_for_sufficient_deposit() {
+        let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
+
+        let (amount, fees) = determine_btc_to_swap(
+            async { Ok(quote_with_min(0.01)) },
+            Amount::from_btc(0.0001).unwrap(),
+            get_dummy_address(),
+            || async { Ok(Amount::from_btc(0.0101)?) },
+            || async { Ok(Amount::from_btc(0.01)?) },
+            || async { Ok(()) },
+        )
+        .await
+        .unwrap();
+
+        let expected_amount = Amount::from_btc(0.01).unwrap();
+        let expected_fees = Amount::from_btc(0.0001).unwrap();
+
+        assert_eq!((amount, fees), (expected_amount, expected_fees))
+    }
+
+    #[tokio::test]
+    async fn given_no_initial_balance_and_transfers_less_than_min_keep_waiting() {
+        let _guard = subscriber::set_default(tracing_subscriber::fmt().with_test_writer().finish());
+
+        let error = tokio::time::timeout(
+            Duration::from_secs(1),
+            determine_btc_to_swap(
+                async { Ok(quote_with_min(0.1)) },
+                Amount::ZERO,
+                get_dummy_address(),
+                || async { Ok(Amount::from_btc(0.0101)?) },
+                || async { Ok(Amount::from_btc(0.01)?) },
+                || async { Ok(()) },
+            ),
+        )
+        .await
+        .unwrap_err();
+
+        assert!(matches!(error, tokio::time::error::Elapsed { .. }))
     }
 
     fn quote_with_max(btc: f64) -> BidQuote {
         BidQuote {
             price: Amount::from_btc(0.001).unwrap(),
             max_quantity: Amount::from_btc(btc).unwrap(),
+            min_quantity: Amount::ZERO,
+        }
+    }
+
+    fn quote_with_min(btc: f64) -> BidQuote {
+        BidQuote {
+            price: Amount::from_btc(0.001).unwrap(),
+            max_quantity: Amount::max_value(),
+            min_quantity: Amount::from_btc(btc).unwrap(),
         }
     }
 

swap/src/network/quote.rs

@@ -30,6 +30,9 @@ pub struct BidQuote {
     /// The price at which the maker is willing to buy at.
     #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
     pub price: bitcoin::Amount,
+    /// The minimum quantity the maker is willing to buy.
+    #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
+    pub min_quantity: bitcoin::Amount,
     /// The maximum quantity the maker is willing to buy.
     #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
     pub max_quantity: bitcoin::Amount,

swap/src/network/spot_price.rs

@@ -43,7 +43,13 @@ pub enum Response {
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub enum Error {
     NoSwapsAccepted,
-    MaxBuyAmountExceeded {
+    AmountBelowMinimum {
+        #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
+        min: bitcoin::Amount,
+        #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
+        buy: bitcoin::Amount,
+    },
+    AmountAboveMaximum {
         #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
         max: bitcoin::Amount,
         #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
@@ -74,8 +80,16 @@ mod tests {
         let serialized = serde_json::to_string(&Response::Error(Error::NoSwapsAccepted)).unwrap();
         assert_eq!(error, serialized);
 
-        let error = r#"{"Error":{"MaxBuyAmountExceeded":{"max":0,"buy":0}}}"#.to_string();
-        let serialized = serde_json::to_string(&Response::Error(Error::MaxBuyAmountExceeded {
+        let error = r#"{"Error":{"AmountBelowMinimum":{"min":0,"buy":0}}}"#.to_string();
+        let serialized = serde_json::to_string(&Response::Error(Error::AmountBelowMinimum {
+            min: Default::default(),
+            buy: Default::default(),
+        }))
+        .unwrap();
+        assert_eq!(error, serialized);
+
+        let error = r#"{"Error":{"AmountAboveMaximum":{"max":0,"buy":0}}}"#.to_string();
+        let serialized = serde_json::to_string(&Response::Error(Error::AmountAboveMaximum {
             max: Default::default(),
             buy: Default::default(),
         }))

swap/src/network/swarm.rs

@@ -12,6 +12,7 @@ pub fn alice<LR>(
     seed: &Seed,
     balance: monero::Amount,
     lock_fee: monero::Amount,
+    min_buy: bitcoin::Amount,
     max_buy: bitcoin::Amount,
     latest_rate: LR,
     resume_only: bool,
@@ -21,7 +22,14 @@ where
 {
     with_clear_net(
         seed,
-        alice::Behaviour::new(balance, lock_fee, max_buy, latest_rate, resume_only),
+        alice::Behaviour::new(
+            balance,
+            lock_fee,
+            min_buy,
+            max_buy,
+            latest_rate,
+            resume_only,
+        ),
     )
 }
 

swap/src/protocol/alice/behaviour.rs

@@ -84,6 +84,7 @@ where
     pub fn new(
         balance: monero::Amount,
         lock_fee: monero::Amount,
+        min_buy: bitcoin::Amount,
         max_buy: bitcoin::Amount,
         latest_rate: LR,
         resume_only: bool,
@@ -93,6 +94,7 @@ where
             spot_price: spot_price::Behaviour::new(
                 balance,
                 lock_fee,
+                min_buy,
                 max_buy,
                 latest_rate,
                 resume_only,

swap/src/protocol/alice/event_loop.rs

@@ -43,6 +43,7 @@ where
     monero_wallet: Arc<monero::Wallet>,
     db: Arc<Database>,
     latest_rate: LR,
+    min_buy: bitcoin::Amount,
     max_buy: bitcoin::Amount,
 
     swap_sender: mpsc::Sender<Swap>,
@@ -74,6 +75,7 @@ where
         monero_wallet: Arc<monero::Wallet>,
         db: Arc<Database>,
         latest_rate: LR,
+        min_buy: bitcoin::Amount,
         max_buy: bitcoin::Amount,
     ) -> Result<(Self, mpsc::Receiver<Swap>)> {
         let swap_channel = MpscChannels::default();
@@ -86,6 +88,7 @@ where
             db,
             latest_rate,
             swap_sender: swap_channel.sender,
+            min_buy,
             max_buy,
             recv_encrypted_signature: Default::default(),
             inflight_encrypted_signatures: Default::default(),
@@ -206,7 +209,9 @@ where
                         }
                         SwarmEvent::Behaviour(OutEvent::SwapRequestDeclined { peer, error }) => {
                             match error {
-                                Error::ResumeOnlyMode | Error::MaxBuyAmountExceeded { .. } => {
+                                Error::ResumeOnlyMode
+                                | Error::AmountBelowMinimum { .. }
+                                | Error::AmountAboveMaximum { .. } => {
                                     tracing::warn!(%peer, "Ignoring spot price request because: {}", error);
                                 }
                                 Error::BalanceTooLow { .. }
@@ -228,7 +233,7 @@ where
                                 }
                             }
 
-                            let quote = match self.make_quote(self.max_buy).await {
+                            let quote = match self.make_quote(self.min_buy, self.max_buy).await {
                                 Ok(quote) => quote,
                                 Err(e) => {
                                     tracing::warn!(%peer, "Failed to make quote: {:#}", e);
@@ -355,7 +360,11 @@ where
         }
     }
 
-    async fn make_quote(&mut self, max_buy: bitcoin::Amount) -> Result<BidQuote> {
+    async fn make_quote(
+        &mut self,
+        min_buy: bitcoin::Amount,
+        max_buy: bitcoin::Amount,
+    ) -> Result<BidQuote> {
         let rate = self
             .latest_rate
             .latest_rate()
@@ -363,6 +372,7 @@ where
 
         Ok(BidQuote {
             price: rate.ask().context("Failed to compute asking price")?,
+            min_quantity: min_buy,
             max_quantity: max_buy,
         })
     }

swap/src/protocol/alice/spot_price.rs

@@ -44,6 +44,8 @@ where
     #[behaviour(ignore)]
     lock_fee: monero::Amount,
     #[behaviour(ignore)]
+    min_buy: bitcoin::Amount,
+    #[behaviour(ignore)]
     max_buy: bitcoin::Amount,
     #[behaviour(ignore)]
     latest_rate: LR,
@@ -62,6 +64,7 @@ where
     pub fn new(
         balance: monero::Amount,
         lock_fee: monero::Amount,
+        min_buy: bitcoin::Amount,
         max_buy: bitcoin::Amount,
         latest_rate: LR,
         resume_only: bool,
@@ -75,6 +78,7 @@ where
             events: Default::default(),
             balance,
             lock_fee,
+            min_buy,
             max_buy,
             latest_rate,
             resume_only,
@@ -156,8 +160,17 @@ where
         }
 
         let btc = request.btc;
+
+        if btc < self.min_buy {
+            self.decline(peer, channel, Error::AmountBelowMinimum {
+                min: self.min_buy,
+                buy: btc,
+            });
+            return;
+        }
+
         if btc > self.max_buy {
-            self.decline(peer, channel, Error::MaxBuyAmountExceeded {
+            self.decline(peer, channel, Error::AmountAboveMaximum {
                 max: self.max_buy,
                 buy: btc,
             });
@@ -183,7 +196,10 @@ where
         let xmr_lock_fees = self.lock_fee;
 
         if xmr_balance < xmr + xmr_lock_fees {
-            self.decline(peer, channel, Error::BalanceTooLow { buy: btc });
+            self.decline(peer, channel, Error::BalanceTooLow {
+                balance: xmr_balance,
+                buy: btc,
+            });
             return;
         }
 
@@ -215,13 +231,21 @@ impl From<OutEvent> for alice::OutEvent {
 pub enum Error {
     #[error("ASB is running in resume-only mode")]
     ResumeOnlyMode,
-    #[error("Maximum buy {max} exceeded {buy}")]
-    MaxBuyAmountExceeded {
+    #[error("Amount {buy} below minimum {min}")]
+    AmountBelowMinimum {
+        min: bitcoin::Amount,
+        buy: bitcoin::Amount,
+    },
+    #[error("Amount {buy} above maximum {max}")]
+    AmountAboveMaximum {
         max: bitcoin::Amount,
         buy: bitcoin::Amount,
     },
-    #[error("This seller's XMR balance is currently too low to fulfill the swap request to buy {buy}, please try again later")]
-    BalanceTooLow { buy: bitcoin::Amount },
+    #[error("Balance {balance} too low to fulfill swapping {buy}")]
+    BalanceTooLow {
+        balance: monero::Amount,
+        buy: bitcoin::Amount,
+    },
 
     #[error("Failed to fetch latest rate")]
     LatestRateFetchFailed(#[source] Box<dyn std::error::Error + Send + 'static>),
@@ -234,11 +258,15 @@ impl Error {
     pub fn to_error_response(&self) -> spot_price::Error {
         match self {
             Error::ResumeOnlyMode => spot_price::Error::NoSwapsAccepted,
-            Error::MaxBuyAmountExceeded { max, buy } => spot_price::Error::MaxBuyAmountExceeded {
+            Error::AmountBelowMinimum { min, buy } => spot_price::Error::AmountBelowMinimum {
+                min: *min,
+                buy: *buy,
+            },
+            Error::AmountAboveMaximum { max, buy } => spot_price::Error::AmountAboveMaximum {
                 max: *max,
                 buy: *buy,
             },
-            Error::BalanceTooLow { buy } => spot_price::Error::BalanceTooLow { buy: *buy },
+            Error::BalanceTooLow { buy, .. } => spot_price::Error::BalanceTooLow { buy: *buy },
             Error::LatestRateFetchFailed(_) | Error::SellQuoteCalculationFailed(_) => {
                 spot_price::Error::Other
             }
@@ -262,6 +290,7 @@ mod tests {
             Self {
                 balance: monero::Amount::from_monero(1.0).unwrap(),
                 lock_fee: monero::Amount::ZERO,
+                min_buy: bitcoin::Amount::from_btc(0.001).unwrap(),
                 max_buy: bitcoin::Amount::from_btc(0.01).unwrap(),
                 rate: TestRate::default(), // 0.01
                 resume_only: false,
@@ -296,7 +325,10 @@ mod tests {
 
         test.send_request(request);
         test.assert_error(
-            alice::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
+            alice::spot_price::Error::BalanceTooLow {
+                balance: monero::Amount::ZERO,
+                buy: btc_to_swap,
+            },
             bob::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
         )
         .await;
@@ -323,7 +355,10 @@ mod tests {
 
         test.send_request(request);
         test.assert_error(
-            alice::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
+            alice::spot_price::Error::BalanceTooLow {
+                balance: monero::Amount::ZERO,
+                buy: btc_to_swap,
+            },
             bob::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
         )
         .await;
@@ -331,8 +366,12 @@ mod tests {
 
     #[tokio::test]
     async fn given_alice_has_insufficient_balance_because_of_lock_fee_then_returns_error() {
+        let balance = monero::Amount::from_monero(1.0).unwrap();
+
         let mut test = SpotPriceTest::setup(
-            AliceBehaviourValues::default().with_lock_fee(monero::Amount::from_piconero(1)),
+            AliceBehaviourValues::default()
+                .with_balance(balance)
+                .with_lock_fee(monero::Amount::from_piconero(1)),
         )
         .await;
 
@@ -342,14 +381,42 @@ mod tests {
 
         test.send_request(request);
         test.assert_error(
-            alice::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
+            alice::spot_price::Error::BalanceTooLow {
+                balance,
+                buy: btc_to_swap,
+            },
             bob::spot_price::Error::BalanceTooLow { buy: btc_to_swap },
         )
         .await;
     }
 
     #[tokio::test]
-    async fn given_max_buy_exceeded_then_returns_error() {
+    async fn given_below_min_buy_then_returns_error() {
+        let min_buy = bitcoin::Amount::from_btc(0.001).unwrap();
+
+        let mut test =
+            SpotPriceTest::setup(AliceBehaviourValues::default().with_min_buy(min_buy)).await;
+
+        let btc_to_swap = bitcoin::Amount::from_btc(0.0001).unwrap();
+
+        let request = spot_price::Request { btc: btc_to_swap };
+
+        test.send_request(request);
+        test.assert_error(
+            alice::spot_price::Error::AmountBelowMinimum {
+                buy: btc_to_swap,
+                min: min_buy,
+            },
+            bob::spot_price::Error::AmountBelowMinimum {
+                buy: btc_to_swap,
+                min: min_buy,
+            },
+        )
+        .await;
+    }
+
+    #[tokio::test]
+    async fn given_above_max_buy_then_returns_error() {
         let max_buy = bitcoin::Amount::from_btc(0.001).unwrap();
 
         let mut test =
@@ -361,11 +428,11 @@ mod tests {
 
         test.send_request(request);
         test.assert_error(
-            alice::spot_price::Error::MaxBuyAmountExceeded {
+            alice::spot_price::Error::AmountAboveMaximum {
                 buy: btc_to_swap,
                 max: max_buy,
             },
-            bob::spot_price::Error::MaxBuyAmountExceeded {
+            bob::spot_price::Error::AmountAboveMaximum {
                 buy: btc_to_swap,
                 max: max_buy,
             },
@@ -442,6 +509,7 @@ mod tests {
                 Behaviour::new(
                     values.balance,
                     values.lock_fee,
+                    values.min_buy,
                     values.max_buy,
                     values.rate.clone(),
                     values.resume_only,
@@ -508,12 +576,25 @@ mod tests {
                     // TODO: Somehow make PartialEq work on Alice's spot_price::Error
                     match (alice_assert, error) {
                         (
-                            alice::spot_price::Error::BalanceTooLow { .. },
-                            alice::spot_price::Error::BalanceTooLow { .. },
+                            alice::spot_price::Error::BalanceTooLow {
+                                balance: balance1,
+                                buy: buy1,
+                            },
+                            alice::spot_price::Error::BalanceTooLow {
+                                balance: balance2,
+                                buy: buy2,
+                            },
+                        ) => {
+                            assert_eq!(balance1, balance2);
+                            assert_eq!(buy1, buy2);
+                        }
+                        (
+                            alice::spot_price::Error::AmountBelowMinimum { .. },
+                            alice::spot_price::Error::AmountBelowMinimum { .. },
                         )
                         | (
-                            alice::spot_price::Error::MaxBuyAmountExceeded { .. },
-                            alice::spot_price::Error::MaxBuyAmountExceeded { .. },
+                            alice::spot_price::Error::AmountAboveMaximum { .. },
+                            alice::spot_price::Error::AmountAboveMaximum { .. },
                         )
                         | (
                             alice::spot_price::Error::LatestRateFetchFailed(_),
@@ -555,6 +636,7 @@ mod tests {
     struct AliceBehaviourValues {
         pub balance: monero::Amount,
         pub lock_fee: monero::Amount,
+        pub min_buy: bitcoin::Amount,
         pub max_buy: bitcoin::Amount,
         pub rate: TestRate, // 0.01
         pub resume_only: bool,
@@ -571,6 +653,11 @@ mod tests {
             self
         }
 
+        pub fn with_min_buy(mut self, min_buy: bitcoin::Amount) -> AliceBehaviourValues {
+            self.min_buy = min_buy;
+            self
+        }
+
         pub fn with_max_buy(mut self, max_buy: bitcoin::Amount) -> AliceBehaviourValues {
             self.max_buy = max_buy;
             self

swap/src/protocol/bob/spot_price.rs

@@ -41,8 +41,13 @@ crate::impl_from_rr_event!(SpotPriceOutEvent, OutEvent, PROTOCOL);
 pub enum Error {
     #[error("Seller currently does not accept incoming swap requests, please try again later")]
     NoSwapsAccepted,
+    #[error("Seller refused to buy {buy} because the minimum configured buy limit is {min}")]
+    AmountBelowMinimum {
+        min: bitcoin::Amount,
+        buy: bitcoin::Amount,
+    },
     #[error("Seller refused to buy {buy} because the maximum configured buy limit is {max}")]
-    MaxBuyAmountExceeded {
+    AmountAboveMaximum {
         max: bitcoin::Amount,
         buy: bitcoin::Amount,
     },
@@ -59,8 +64,11 @@ impl From<spot_price::Error> for Error {
     fn from(error: spot_price::Error) -> Self {
         match error {
             spot_price::Error::NoSwapsAccepted => Error::NoSwapsAccepted,
-            spot_price::Error::MaxBuyAmountExceeded { max, buy } => {
-                Error::MaxBuyAmountExceeded { max, buy }
+            spot_price::Error::AmountBelowMinimum { min, buy } => {
+                Error::AmountBelowMinimum { min, buy }
+            }
+            spot_price::Error::AmountAboveMaximum { max, buy } => {
+                Error::AmountAboveMaximum { max, buy }
             }
             spot_price::Error::BalanceTooLow { buy } => Error::BalanceTooLow { buy },
             spot_price::Error::Other => Error::Other,

swap/tests/harness/mod.rs

@@ -226,6 +226,7 @@ async fn start_alice(
 
     let current_balance = monero_wallet.get_balance().await.unwrap();
     let lock_fee = monero_wallet.static_tx_fee_estimate();
+    let min_buy = bitcoin::Amount::from_sat(u64::MIN);
     let max_buy = bitcoin::Amount::from_sat(u64::MAX);
     let latest_rate = FixedRate::default();
     let resume_only = false;
@@ -234,6 +235,7 @@ async fn start_alice(
         &seed,
         current_balance,
         lock_fee,
+        min_buy,
         max_buy,
         latest_rate,
         resume_only,
@@ -248,7 +250,8 @@ async fn start_alice(
         monero_wallet,
         db,
         FixedRate::default(),
-        bitcoin::Amount::ONE_BTC,
+        min_buy,
+        max_buy,
     )
     .unwrap();