From 019d6c725a121e12f1bd4520bad14a43a6b9f84e Mon Sep 17 00:00:00 2001
From: Daniel Karzel <daniel@comit.network>
Date: Thu, 25 Feb 2021 13:54:12 +1100
Subject: [PATCH] Maximum sell amount for ASB that defaults to 0.5 XMR

---
 swap/src/asb/command.rs               | 12 +++++++++++-
 swap/src/bin/asb.rs                   |  3 ++-
 swap/src/protocol/alice/event_loop.rs | 20 +++++++++++++++++++-
 swap/tests/testutils/mod.rs           |  1 +
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/swap/src/asb/command.rs b/swap/src/asb/command.rs
index a34ae43d..c29ad9d5 100644
--- a/swap/src/asb/command.rs
+++ b/swap/src/asb/command.rs
@@ -1,3 +1,5 @@
+use crate::monero::Amount;
+use anyhow::Result;
 use std::path::PathBuf;
 
 #[derive(structopt::StructOpt, Debug)]
@@ -16,6 +18,14 @@ pub struct Arguments {
 #[derive(structopt::StructOpt, Debug)]
 #[structopt(name = "xmr_btc-swap", about = "XMR BTC atomic swap")]
 pub enum Command {
-    Start,
+    Start {
+        #[structopt(long = "max-sell-xmr", help = "The maximum amount of XMR the ASB is willing to sell.", default_value="0.5", parse(try_from_str = parse_xmr))]
+        max_sell: Amount,
+    },
     History,
 }
+
+fn parse_xmr(str: &str) -> Result<Amount> {
+    let amount = Amount::parse_monero(str)?;
+    Ok(amount)
+}
diff --git a/swap/src/bin/asb.rs b/swap/src/bin/asb.rs
index ed985d47..4bc1f845 100644
--- a/swap/src/bin/asb.rs
+++ b/swap/src/bin/asb.rs
@@ -79,7 +79,7 @@ async fn main() -> Result<()> {
     let wallet_data_dir = config.data.dir.join("wallet");
 
     match opt.cmd {
-        Command::Start => {
+        Command::Start { max_sell } => {
             let seed = Seed::from_file_or_generate(&config.data.dir)
                 .expect("Could not retrieve/initialize seed");
 
@@ -107,6 +107,7 @@ async fn main() -> Result<()> {
                 Arc::new(monero_wallet),
                 Arc::new(db),
                 rate_service,
+                max_sell,
             )
             .unwrap();
 
diff --git a/swap/src/protocol/alice/event_loop.rs b/swap/src/protocol/alice/event_loop.rs
index e061d6bf..7c24f1d5 100644
--- a/swap/src/protocol/alice/event_loop.rs
+++ b/swap/src/protocol/alice/event_loop.rs
@@ -4,7 +4,7 @@ use crate::{
     database::Database,
     execution_params::ExecutionParams,
     monero,
-    monero::BalanceTooLow,
+    monero::{Amount, BalanceTooLow},
     network,
     network::{transport, TokioExecutor},
     protocol::{
@@ -88,6 +88,7 @@ pub struct EventLoop<RS> {
     db: Arc<Database>,
     listen_address: Multiaddr,
     rate_service: RS,
+    max_sell: Amount,
 
     recv_encrypted_signature: broadcast::Sender<EncryptedSignature>,
     send_transfer_proof: mpsc::Receiver<(PeerId, TransferProof)>,
@@ -102,6 +103,7 @@ impl<RS> EventLoop<RS>
 where
     RS: LatestRate,
 {
+    #[allow(clippy::too_many_arguments)]
     pub fn new(
         listen_address: Multiaddr,
         seed: Seed,
@@ -110,6 +112,7 @@ where
         monero_wallet: Arc<monero::Wallet>,
         db: Arc<Database>,
         rate_service: RS,
+        max_sell: Amount,
     ) -> Result<(Self, mpsc::Receiver<RemoteHandle<Result<AliceState>>>)> {
         let identity = network::Seed::new(seed).derive_libp2p_identity();
         let behaviour = Behaviour::default();
@@ -142,6 +145,7 @@ where
             send_transfer_proof: send_transfer_proof.receiver,
             send_transfer_proof_sender: send_transfer_proof.sender,
             swap_handle_sender: swap_handle.sender,
+            max_sell,
         };
         Ok((event_loop, swap_handle.receiver))
     }
@@ -216,6 +220,13 @@ where
         let btc_amount = quote_request.btc_amount;
         let xmr_amount = rate.sell_quote(btc_amount)?;
 
+        if xmr_amount > self.max_sell {
+            anyhow!(MaximumSellAmountExceeded {
+                actual: xmr_amount,
+                max_sell: self.max_sell
+            });
+        }
+
         let xmr_balance = monero_wallet.get_balance().await?;
         let xmr_lock_fees = monero_wallet.static_tx_fee_estimate();
 
@@ -288,3 +299,10 @@ where
         Ok(())
     }
 }
+
+#[derive(Debug, Clone, Copy, thiserror::Error)]
+#[error("The amount {actual} exceeds the configured maximum sell amount of {max_sell} XMR")]
+pub struct MaximumSellAmountExceeded {
+    pub max_sell: Amount,
+    pub actual: Amount,
+}
diff --git a/swap/tests/testutils/mod.rs b/swap/tests/testutils/mod.rs
index 646a3cc4..3c1b8b09 100644
--- a/swap/tests/testutils/mod.rs
+++ b/swap/tests/testutils/mod.rs
@@ -383,6 +383,7 @@ where
         alice_monero_wallet.clone(),
         alice_db,
         fixed_rate::RateService::default(),
+        alice_starting_balances.xmr,
     )
     .unwrap();