From babd1d7b609454b2f403903d5e9b76dfb2222dfb Mon Sep 17 00:00:00 2001
From: Daniel Karzel <daniel@comit.network>
Date: Tue, 16 Feb 2021 16:00:27 +1100
Subject: [PATCH] Wait for refund if insufficient Monero is locked up

---
 swap/src/protocol/bob/state.rs | 15 +++++++++------
 swap/src/protocol/bob/swap.rs  | 11 ++++++++++-
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/swap/src/protocol/bob/state.rs b/swap/src/protocol/bob/state.rs
index aa32b5e4..83780a9b 100644
--- a/swap/src/protocol/bob/state.rs
+++ b/swap/src/protocol/bob/state.rs
@@ -7,7 +7,7 @@ use crate::{
     },
     execution_params::ExecutionParams,
     monero,
-    monero::{monero_private_key, TransferProof},
+    monero::{monero_private_key, InsufficientFunds, TransferProof},
     protocol::{
         alice::{Message1, Message3},
         bob::{EncryptedSignature, Message0, Message2, Message4},
@@ -310,7 +310,7 @@ impl State3 {
         xmr_wallet: &W,
         transfer_proof: TransferProof,
         monero_wallet_restore_blockheight: u32,
-    ) -> Result<State4>
+    ) -> Result<Result<State4, InsufficientFunds>>
     where
         W: monero::WatchForTransfer,
     {
@@ -319,7 +319,7 @@ impl State3 {
         ));
         let S = self.S_a_monero + S_b_monero;
 
-        xmr_wallet
+        if let Err(e) = xmr_wallet
             .watch_for_transfer(
                 S,
                 self.v.public(),
@@ -327,9 +327,12 @@ impl State3 {
                 self.xmr,
                 self.min_monero_confirmations,
             )
-            .await?;
+            .await
+        {
+            return Ok(Err(e));
+        }
 
-        Ok(State4 {
+        Ok(Ok(State4 {
             A: self.A,
             b: self.b,
             s_b: self.s_b,
@@ -343,7 +346,7 @@ impl State3 {
             tx_cancel_sig_a: self.tx_cancel_sig_a,
             tx_refund_encsig: self.tx_refund_encsig,
             monero_wallet_restore_blockheight,
-        })
+        }))
     }
 
     pub async fn wait_for_cancel_timelock_to_expire<W>(&self, bitcoin_wallet: &W) -> Result<()>
diff --git a/swap/src/protocol/bob/swap.rs b/swap/src/protocol/bob/swap.rs
index d645e83e..72686335 100644
--- a/swap/src/protocol/bob/swap.rs
+++ b/swap/src/protocol/bob/swap.rs
@@ -4,6 +4,7 @@ use crate::{
     database::{Database, Swap},
     execution_params::ExecutionParams,
     monero,
+    monero::InsufficientFunds,
     protocol::bob::{self, event_loop::EventLoopHandle, state::*, QuoteRequest},
 };
 use anyhow::{bail, Result};
@@ -186,7 +187,15 @@ async fn run_until_internal(
 
                     select! {
                         state4 = xmr_lock_watcher => {
-                            BobState::XmrLocked(state4?)
+                            match state4? {
+                                Ok(state4) => BobState::XmrLocked(state4),
+                                Err(InsufficientFunds {..}) => {
+                                     info!("The other party has locked insufficient Monero funds! Waiting for refund...");
+                                     state.wait_for_cancel_timelock_to_expire(bitcoin_wallet.as_ref()).await?;
+                                     let state4 = state.state4();
+                                     BobState::CancelTimelockExpired(state4)
+                                },
+                            }
                         },
                         _ = cancel_timelock_expires => {
                             let state4 = state.state4();