From a2fc93e582fc10b786b26bdbb382c33b3bb37255 Mon Sep 17 00:00:00 2001
From: Franck Royer <franck@coblox.tech>
Date: Mon, 21 Dec 2020 16:02:49 +1100
Subject: [PATCH] Avoid code duplication and nested returns

---
 swap/src/alice/swap.rs | 15 ++-------------
 swap/src/bitcoin.rs    | 27 +++++++++++++++++++++++----
 swap/src/bob/swap.rs   | 16 ++--------------
 swap/src/lib.rs        |  2 --
 4 files changed, 27 insertions(+), 33 deletions(-)

diff --git a/swap/src/alice/swap.rs b/swap/src/alice/swap.rs
index 4ca86671..34cb093d 100644
--- a/swap/src/alice/swap.rs
+++ b/swap/src/alice/swap.rs
@@ -16,11 +16,10 @@ use crate::{
     state,
     state::{Alice, Swap},
     storage::Database,
-    SwapAmounts, TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE,
+    SwapAmounts,
 };
 use anyhow::{bail, Result};
 use async_recursion::async_recursion;
-use bitcoin_harness::bitcoind_rpc::jsonrpc_client::JsonRpcError;
 use futures::{
     future::{select, Either},
     pin_mut,
@@ -474,17 +473,7 @@ pub async fn run_until(
                 .await
             }
             AliceState::T1Expired { state3 } => {
-                if let Err(error) = state3.submit_tx_cancel(bitcoin_wallet.as_ref()).await {
-                    if let Some(json_rpc_err) = error.downcast_ref::<JsonRpcError>() {
-                        if json_rpc_err.code == TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE {
-                            info!("Failed to send cancel transaction, assuming that is was already included by the other party...");
-                        } else {
-                            return Err(error);
-                        }
-                    } else {
-                        return Err(error);
-                    }
-                };
+                state3.submit_tx_cancel(bitcoin_wallet.as_ref()).await?;
 
                 let state = AliceState::BtcCancelled { state3 };
                 let db_state = (&state).into();
diff --git a/swap/src/bitcoin.rs b/swap/src/bitcoin.rs
index 5dfc8edd..5febb47e 100644
--- a/swap/src/bitcoin.rs
+++ b/swap/src/bitcoin.rs
@@ -2,7 +2,11 @@ use anyhow::{Context, Result};
 use async_trait::async_trait;
 use backoff::{backoff::Constant as ConstantBackoff, future::FutureOperation as _};
 use bitcoin::util::psbt::PartiallySignedTransaction;
-use bitcoin_harness::{bitcoind_rpc::PsbtBase64, BitcoindRpcApi};
+use bitcoin_harness::{
+    bitcoind_rpc,
+    bitcoind_rpc::{jsonrpc_client, jsonrpc_client::JsonRpcError, PsbtBase64},
+    BitcoindRpcApi,
+};
 use reqwest::Url;
 use std::time::Duration;
 use tokio::time::interval;
@@ -18,6 +22,7 @@ pub use ::bitcoin::{Address, Transaction};
 pub use xmr_btc::bitcoin::*;
 
 pub const TX_LOCK_MINE_TIMEOUT: u64 = 3600;
+const TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE: i64 = -27;
 
 #[derive(Debug)]
 pub struct Wallet {
@@ -105,9 +110,23 @@ impl SignTxLock for Wallet {
 #[async_trait]
 impl BroadcastSignedTransaction for Wallet {
     async fn broadcast_signed_transaction(&self, transaction: Transaction) -> Result<Txid> {
-        let txid = self.inner.send_raw_transaction(transaction).await?;
-        tracing::debug!("Bitcoin tx broadcasted! TXID = {}", txid);
-        Ok(txid)
+        let txid = transaction.txid();
+        match self.inner.send_raw_transaction(transaction).await {
+            Err(bitcoind_rpc::Error::JsonRpcClient(jsonrpc_client::Error::JsonRpc(
+                JsonRpcError {
+                    code: TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE,
+                    ..
+                },
+            ))) => {
+                tracing::info!("Cancel transaction is already confirmed.");
+                Ok(txid)
+            }
+            Err(err) => Err(err.into()),
+            Ok(txid) => {
+                tracing::debug!("Bitcoin tx broadcasted! TXID = {}", txid);
+                Ok(txid)
+            }
+        }
     }
 }
 
diff --git a/swap/src/bob/swap.rs b/swap/src/bob/swap.rs
index 556f15c4..c38dda06 100644
--- a/swap/src/bob/swap.rs
+++ b/swap/src/bob/swap.rs
@@ -3,11 +3,10 @@ use crate::{
     state,
     state::{Bob, Swap},
     storage::Database,
-    SwapAmounts, TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE,
+    SwapAmounts,
 };
 use anyhow::{bail, Result};
 use async_recursion::async_recursion;
-use bitcoin_harness::bitcoind_rpc::jsonrpc_client::JsonRpcError;
 use libp2p::{core::Multiaddr, PeerId};
 use rand::{CryptoRng, RngCore};
 use std::{convert::TryFrom, fmt, sync::Arc};
@@ -345,18 +344,7 @@ where
                 .await
             }
             BobState::T1Expired(state4) => {
-                let result = state4.submit_tx_cancel(bitcoin_wallet.as_ref()).await;
-                if let Err(error) = result {
-                    if let Some(json_rpc_err) = error.downcast_ref::<JsonRpcError>() {
-                        if json_rpc_err.code == TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE {
-                            info!("Failed to send cancel transaction, assuming that is was already included by the other party...");
-                        } else {
-                            return Err(error);
-                        }
-                    } else {
-                        return Err(error);
-                    }
-                };
+                state4.submit_tx_cancel(bitcoin_wallet.as_ref()).await?;
 
                 let state = BobState::Cancelled(state4);
                 db.insert_latest_state(swap_id, state::Swap::Bob(state.clone().into()))
diff --git a/swap/src/lib.rs b/swap/src/lib.rs
index 7b95a0d4..b71d005f 100644
--- a/swap/src/lib.rs
+++ b/swap/src/lib.rs
@@ -15,8 +15,6 @@ pub mod trace;
 
 pub type Never = std::convert::Infallible;
 
-const TRANSACTION_ALREADY_IN_BLOCKCHAIN_ERROR_CODE: i64 = -27;
-
 /// Commands sent from Bob to the main task.
 #[derive(Clone, Copy, Debug)]
 pub enum Cmd {