Merge #608

608: Smoothen the CLI's interface a bit r=da-kami a=thomaseizinger

- Add `--change-address` to the `buy-xmr` command.
- Remove `--receive-address` from the `resume` command.



Co-authored-by: Thomas Eizinger <thomas@eizinger.io>

CHANGELOG.md

@@ -19,6 +19,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   The rendezvous node address (`rendezvous_point`), as well as the ASB's external addresses (`external_addresses`) to be registered, is configured in the `network` section of the ASB config file.
   A rendezvous node is provided at `/dnsaddr/rendezvous.coblox.tech/p2p/12D3KooWQUt9DkNZxEn2R5ymJzWj15MpG6mTW84kyd8vDaRZi46o` which is used as default for discovery in the CLI.
   Upon discovery using `list-sellers` CLI users are provided with quote and connection information for each ASB discovered through the rendezvous node.
+- A mandatory `--change-address` parameter to the CLI's `buy-xmr` command.
+  The provided address is used to transfer Bitcoin in case of a refund and in case the user transfers more than the specified amount into the swap.
+  For more information see [#513](https://github.com/comit-network/xmr-btc-swap/issues/513).
 
 ### Fixed
 
@@ -39,6 +42,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   The CLI can use regular TCP connections and having both - TCP and websockets - causes problems and unnecessary overhead.
 - The `--seller-addr` parameter from the CLI's `resume` command.
   This information is now loaded from the database.
+- The `--receive-address` parameter from the CLI's `resume` command.
+  This information is now loaded from the database.
 
 ## [0.7.0] - 2021-05-28
 

swap/Cargo.toml

@@ -45,7 +45,7 @@ rust_decimal_macros = "1"
 serde = { version = "1", features = [ "derive" ] }
 serde_cbor = "0.11"
 serde_json = "1"
-serde_with = { version = "1.9.4", features = [ "macros" ] }
+serde_with = { version = "1", features = [ "macros" ] }
 sha2 = "0.9"
 sigma_fun = { git = "https://github.com/LLFourn/secp256kfun", default-features = false, features = [ "ed25519", "serde" ] }
 sled = "0.34"

swap/src/bin/asb.rs

@@ -231,7 +231,9 @@ async fn main() -> Result<()> {
                 }
             };
 
-            let psbt = bitcoin_wallet.send_to_address(address, amount).await?;
+            let psbt = bitcoin_wallet
+                .send_to_address(address, amount, None)
+                .await?;
             let signed_tx = bitcoin_wallet.sign_and_finalize(psbt).await?;
 
             bitcoin_wallet.broadcast(signed_tx, "withdraw").await?;

swap/src/bin/swap.rs

@@ -12,7 +12,7 @@
 #![forbid(unsafe_code)]
 #![allow(non_snake_case)]
 
-use anyhow::{bail, Context, Result};
+use anyhow::{Context, Result};
 use comfy_table::Table;
 use qrcode::render::unicode;
 use qrcode::QrCode;
@@ -59,6 +59,7 @@ async fn main() -> Result<()> {
             seller,
             bitcoin_electrum_rpc_url,
             bitcoin_target_block,
+            bitcoin_change_address,
             monero_receive_address,
             monero_daemon_address,
             tor_socks5_port,
@@ -113,6 +114,8 @@ async fn main() -> Result<()> {
             info!(%amount, %fees, %swap_id,  "Swapping");
 
             db.insert_peer_id(swap_id, seller_peer_id).await?;
+            db.insert_monero_address(swap_id, monero_receive_address)
+                .await?;
 
             let swap = Swap::new(
                 db,
@@ -122,6 +125,7 @@ async fn main() -> Result<()> {
                 env_config,
                 event_loop_handle,
                 monero_receive_address,
+                bitcoin_change_address,
                 amount,
             );
 
@@ -153,7 +157,6 @@ async fn main() -> Result<()> {
             swap_id,
             bitcoin_electrum_rpc_url,
             bitcoin_target_block,
-            monero_receive_address,
             monero_daemon_address,
             tor_socks5_port,
         } => {
@@ -163,10 +166,6 @@ async fn main() -> Result<()> {
             let seed = Seed::from_file_or_generate(data_dir.as_path())
                 .context("Failed to read in seed file")?;
 
-            if monero_receive_address.network != env_config.monero_network {
-                bail!("The given monero address is on network {:?}, expected address of network {:?}.", monero_receive_address.network, env_config.monero_network)
-            }
-
             let bitcoin_wallet = init_bitcoin_wallet(
                 bitcoin_electrum_rpc_url,
                 &seed,
@@ -198,6 +197,7 @@ async fn main() -> Result<()> {
                 EventLoop::new(swap_id, swarm, seller_peer_id, env_config)?;
             let handle = tokio::spawn(event_loop.run());
 
+            let monero_receive_address = db.get_monero_address(swap_id)?;
             let swap = Swap::from_db(
                 db,
                 swap_id,

swap/src/bitcoin/lock.rs

@@ -24,6 +24,7 @@ impl TxLock {
         amount: Amount,
         A: PublicKey,
         B: PublicKey,
+        change: bitcoin::Address,
     ) -> Result<Self>
     where
         C: EstimateFeeRate,
@@ -34,7 +35,9 @@ impl TxLock {
             .address(wallet.get_network())
             .expect("can derive address from descriptor");
 
-        let psbt = wallet.send_to_address(address, amount).await?;
+        let psbt = wallet
+            .send_to_address(address, amount, Some(change))
+            .await?;
 
         Ok(Self {
             inner: psbt,
@@ -251,7 +254,11 @@ mod tests {
         wallet: &Wallet<(), bdk::database::MemoryDatabase, StaticFeeRate>,
         amount: Amount,
     ) -> PartiallySignedTransaction {
-        TxLock::new(&wallet, amount, A, B).await.unwrap().into()
+        let change = wallet.new_address().await.unwrap();
+        TxLock::new(&wallet, amount, A, B, change)
+            .await
+            .unwrap()
+            .into()
     }
 
     fn alice_and_bob() -> (PublicKey, PublicKey) {

swap/src/bitcoin/wallet.rs

@@ -16,7 +16,6 @@ use reqwest::Url;
 use rust_decimal::prelude::*;
 use rust_decimal::Decimal;
 use rust_decimal_macros::dec;
-use std::cmp::Ordering;
 use std::collections::{BTreeMap, HashMap};
 use std::convert::TryFrom;
 use std::fmt;
@@ -310,11 +309,18 @@ where
         &self,
         address: Address,
         amount: Amount,
+        change_override: Option<Address>,
     ) -> Result<PartiallySignedTransaction> {
         if self.network != address.network {
             bail!("Cannot build PSBT because network of given address is {} but wallet is on network {}", address.network, self.network);
         }
 
+        if let Some(change) = change_override.as_ref() {
+            if self.network != change.network {
+                bail!("Cannot build PSBT because network of given address is {} but wallet is on network {}", change.network, self.network);
+            }
+        }
+
         let wallet = self.wallet.lock().await;
         let client = self.client.lock().await;
         let fee_rate = client.estimate_feerate(self.target_block)?;
@@ -326,22 +332,31 @@ where
         let (psbt, _details) = tx_builder.finish()?;
         let mut psbt: PartiallySignedTransaction = psbt;
 
-        // When subscribing to transactions we depend on the relevant script being at
-        // output index 0, thus we ensure the relevant output to be at index `0`.
-        psbt.outputs.sort_by(|a, _| {
-            if a.witness_script.as_ref() == Some(&script) {
-                Ordering::Less
-            } else {
-                Ordering::Greater
+        match psbt.global.unsigned_tx.output.as_mut_slice() {
+            // our primary output is the 2nd one? reverse the vectors
+            [_, second_txout] if second_txout.script_pubkey == script => {
+                psbt.outputs.reverse();
+                psbt.global.unsigned_tx.output.reverse();
+            }
+            [first_txout, _] if first_txout.script_pubkey == script => {
+                // no need to do anything
             }
-        });
-        psbt.global.unsigned_tx.output.sort_by(|a, _| {
-            if a.script_pubkey == script {
-                Ordering::Less
-            } else {
-                Ordering::Greater
+            [_] => {
+                // single output, no need do anything
             }
-        });
+            _ => bail!("Unexpected transaction layout"),
+        }
+
+        if let ([_, change], [_, psbt_output], Some(change_override)) = (
+            &mut psbt.global.unsigned_tx.output.as_mut_slice(),
+            &mut psbt.outputs.as_mut_slice(),
+            change_override,
+        ) {
+            change.script_pubkey = change_override.script_pubkey();
+            // Might be populated based on the previously set change address, but for the
+            // overwrite we don't know unless we ask the user for more information.
+            psbt_output.bip32_derivation.clear();
+        }
 
         Ok(psbt)
     }
@@ -1062,7 +1077,8 @@ mod tests {
         // if the change output is below dust it will be dropped by the BDK
         for amount in above_dust..(balance - (above_dust - 1)) {
             let (A, B) = (PublicKey::random(), PublicKey::random());
-            let txlock = TxLock::new(&wallet, bitcoin::Amount::from_sat(amount), A, B)
+            let change = wallet.new_address().await.unwrap();
+            let txlock = TxLock::new(&wallet, bitcoin::Amount::from_sat(amount), A, B, change)
                 .await
                 .unwrap();
             let txlock_output = txlock.script_pubkey();
@@ -1077,4 +1093,30 @@ mod tests {
             );
         }
     }
+
+    #[tokio::test]
+    async fn can_override_change_address() {
+        let wallet = Wallet::new_funded_default_fees(50_000);
+        let custom_change = "bcrt1q08pfqpsyrt7acllzyjm8q5qsz5capvyahm49rw"
+            .parse::<Address>()
+            .unwrap();
+
+        let psbt = wallet
+            .send_to_address(
+                wallet.new_address().await.unwrap(),
+                Amount::from_sat(10_000),
+                Some(custom_change.clone()),
+            )
+            .await
+            .unwrap();
+        let transaction = wallet.sign_and_finalize(psbt).await.unwrap();
+
+        match transaction.output.as_slice() {
+            [first, change] => {
+                assert_eq!(first.value, 10_000);
+                assert_eq!(change.script_pubkey, custom_change.script_pubkey());
+            }
+            _ => panic!("expected exactly two outputs"),
+        }
+    }
 }

swap/src/cli/command.rs

@@ -74,11 +74,11 @@ where
                     bitcoin_electrum_rpc_url,
                     bitcoin_target_block,
                 },
-            monero:
-                Monero {
-                    monero_receive_address,
-                    monero_daemon_address,
-                },
+            bitcoin_change_address,
+            monero: Monero {
+                monero_daemon_address,
+            },
+            monero_receive_address,
             tor: Tor { tor_socks5_port },
         } => Arguments {
             env_config: env_config_from(is_testnet),
@@ -92,6 +92,7 @@ where
                     is_testnet,
                 )?,
                 bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
+                bitcoin_change_address,
                 monero_receive_address: validate_monero_address(
                     monero_receive_address,
                     is_testnet,
@@ -117,11 +118,9 @@ where
                     bitcoin_electrum_rpc_url,
                     bitcoin_target_block,
                 },
-            monero:
-                Monero {
-                    monero_receive_address,
-                    monero_daemon_address,
-                },
+            monero: Monero {
+                monero_daemon_address,
+            },
             tor: Tor { tor_socks5_port },
         } => Arguments {
             env_config: env_config_from(is_testnet),
@@ -135,7 +134,6 @@ where
                     is_testnet,
                 )?,
                 bitcoin_target_block: bitcoin_target_block_from(bitcoin_target_block, is_testnet),
-                monero_receive_address,
                 monero_daemon_address: monero_daemon_address_from(
                     monero_daemon_address,
                     is_testnet,
@@ -214,6 +212,7 @@ pub enum Command {
         seller: Multiaddr,
         bitcoin_electrum_rpc_url: Url,
         bitcoin_target_block: usize,
+        bitcoin_change_address: bitcoin::Address,
         monero_receive_address: monero::Address,
         monero_daemon_address: String,
         tor_socks5_port: u16,
@@ -223,7 +222,6 @@ pub enum Command {
         swap_id: Uuid,
         bitcoin_electrum_rpc_url: Url,
         bitcoin_target_block: usize,
-        monero_receive_address: monero::Address,
         monero_daemon_address: String,
         tor_socks5_port: u16,
     },
@@ -287,9 +285,21 @@ pub enum RawCommand {
         #[structopt(flatten)]
         bitcoin: Bitcoin,
 
+        #[structopt(
+            long = "change-address",
+            help = "The bitcoin address where any form of change or excess funds should be sent to"
+        )]
+        bitcoin_change_address: bitcoin::Address,
+
         #[structopt(flatten)]
         monero: Monero,
 
+        #[structopt(long = "receive-address",
+            help = "The monero address where you would like to receive monero",
+            parse(try_from_str = parse_monero_address)
+        )]
+        monero_receive_address: monero::Address,
+
         #[structopt(flatten)]
         tor: Tor,
     },
@@ -346,12 +356,6 @@ pub enum RawCommand {
 
 #[derive(structopt::StructOpt, Debug)]
 pub struct Monero {
-    #[structopt(long = "receive-address",
-        help = "Provide the monero address where you would like to receive monero",
-        parse(try_from_str = parse_monero_address)
-    )]
-    pub monero_receive_address: monero::Address,
-
     #[structopt(
         long = "monero-daemon-address",
         help = "Specify to connect to a monero daemon of your choice: <host>:<port>"
@@ -520,7 +524,9 @@ mod tests {
     const MAINNET: &str = "mainnet";
 
     const MONERO_STAGENET_ADDRESS: &str = "53gEuGZUhP9JMEBZoGaFNzhwEgiG7hwQdMCqFxiyiTeFPmkbt1mAoNybEUvYBKHcnrSgxnVWgZsTvRBaHBNXPa8tHiCU51a";
+    const BITCOIN_TESTNET_ADDRESS: &str = "tb1qr3em6k3gfnyl8r7q0v7t4tlnyxzgxma3lressv";
     const MONERO_MAINNET_ADDRESS: &str = "44Ato7HveWidJYUAVw5QffEcEtSH1DwzSP3FPPkHxNAS4LX9CqgucphTisH978FLHE34YNEx7FcbBfQLQUU8m3NUC4VqsRa";
+    const BITCOIN_MAINNET_ADDRESS: &str = "bc1qe4epnfklcaa0mun26yz5g8k24em5u9f92hy325";
     const MULTI_ADDRESS: &str =
         "/ip4/127.0.0.1/tcp/9939/p2p/12D3KooWCdMKjesXMJz1SiZ7HgotrxuqhQJbP5sgBm2BwP1cqThi";
     const SWAP_ID: &str = "ea030832-3be9-454f-bb98-5ea9a788406b";
@@ -532,6 +538,8 @@ mod tests {
             "buy-xmr",
             "--receive-address",
             MONERO_MAINNET_ADDRESS,
+            "--change-address",
+            BITCOIN_MAINNET_ADDRESS,
             "--seller",
             MULTI_ADDRESS,
         ];
@@ -550,6 +558,8 @@ mod tests {
             "buy-xmr",
             "--receive-address",
             MONERO_STAGENET_ADDRESS,
+            "--change-address",
+            BITCOIN_TESTNET_ADDRESS,
             "--seller",
             MULTI_ADDRESS,
         ];
@@ -569,6 +579,8 @@ mod tests {
             "buy-xmr",
             "--receive-address",
             MONERO_STAGENET_ADDRESS,
+            "--change-address",
+            BITCOIN_TESTNET_ADDRESS,
             "--seller",
             MULTI_ADDRESS,
         ];
@@ -592,6 +604,8 @@ mod tests {
             "buy-xmr",
             "--receive-address",
             MONERO_MAINNET_ADDRESS,
+            "--change-address",
+            BITCOIN_MAINNET_ADDRESS,
             "--seller",
             MULTI_ADDRESS,
         ];
@@ -609,14 +623,7 @@ mod tests {
 
     #[test]
     fn given_resume_on_mainnet_then_defaults_to_mainnet() {
-        let raw_ars = vec![
-            BINARY_NAME,
-            "resume",
-            "--swap-id",
-            SWAP_ID,
-            "--receive-address",
-            MONERO_MAINNET_ADDRESS,
-        ];
+        let raw_ars = vec![BINARY_NAME, "resume", "--swap-id", SWAP_ID];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
 
@@ -628,15 +635,7 @@ mod tests {
 
     #[test]
     fn given_resume_on_testnet_then_defaults_to_testnet() {
-        let raw_ars = vec![
-            BINARY_NAME,
-            "--testnet",
-            "resume",
-            "--swap-id",
-            SWAP_ID,
-            "--receive-address",
-            MONERO_STAGENET_ADDRESS,
-        ];
+        let raw_ars = vec![BINARY_NAME, "--testnet", "resume", "--swap-id", SWAP_ID];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
 
@@ -703,6 +702,8 @@ mod tests {
             "--data-dir",
             data_dir,
             "buy-xmr",
+            "--change-address",
+            BITCOIN_MAINNET_ADDRESS,
             "--receive-address",
             MONERO_MAINNET_ADDRESS,
             "--seller",
@@ -725,6 +726,8 @@ mod tests {
             "--data-dir",
             data_dir,
             "buy-xmr",
+            "--change-address",
+            BITCOIN_TESTNET_ADDRESS,
             "--receive-address",
             MONERO_STAGENET_ADDRESS,
             "--seller",
@@ -748,8 +751,6 @@ mod tests {
             "resume",
             "--swap-id",
             SWAP_ID,
-            "--receive-address",
-            MONERO_MAINNET_ADDRESS,
         ];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
@@ -770,8 +771,6 @@ mod tests {
             "resume",
             "--swap-id",
             SWAP_ID,
-            "--receive-address",
-            MONERO_STAGENET_ADDRESS,
         ];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
@@ -791,6 +790,8 @@ mod tests {
             BINARY_NAME,
             "--debug",
             "buy-xmr",
+            "--change-address",
+            BITCOIN_MAINNET_ADDRESS,
             "--receive-address",
             MONERO_MAINNET_ADDRESS,
             "--seller",
@@ -808,6 +809,8 @@ mod tests {
             "--testnet",
             "--debug",
             "buy-xmr",
+            "--change-address",
+            BITCOIN_TESTNET_ADDRESS,
             "--receive-address",
             MONERO_STAGENET_ADDRESS,
             "--seller",
@@ -820,15 +823,7 @@ mod tests {
             ParseResult::Arguments(Arguments::buy_xmr_testnet_defaults().with_debug())
         );
 
-        let raw_ars = vec![
-            BINARY_NAME,
-            "--debug",
-            "resume",
-            "--swap-id",
-            SWAP_ID,
-            "--receive-address",
-            MONERO_MAINNET_ADDRESS,
-        ];
+        let raw_ars = vec![BINARY_NAME, "--debug", "resume", "--swap-id", SWAP_ID];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
         assert_eq!(
@@ -843,8 +838,6 @@ mod tests {
             "resume",
             "--swap-id",
             SWAP_ID,
-            "--receive-address",
-            MONERO_STAGENET_ADDRESS,
         ];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
@@ -860,6 +853,8 @@ mod tests {
             BINARY_NAME,
             "--json",
             "buy-xmr",
+            "--change-address",
+            BITCOIN_MAINNET_ADDRESS,
             "--receive-address",
             MONERO_MAINNET_ADDRESS,
             "--seller",
@@ -877,6 +872,8 @@ mod tests {
             "--testnet",
             "--json",
             "buy-xmr",
+            "--change-address",
+            BITCOIN_TESTNET_ADDRESS,
             "--receive-address",
             MONERO_STAGENET_ADDRESS,
             "--seller",
@@ -889,15 +886,7 @@ mod tests {
             ParseResult::Arguments(Arguments::buy_xmr_testnet_defaults().with_json())
         );
 
-        let raw_ars = vec![
-            BINARY_NAME,
-            "--json",
-            "resume",
-            "--swap-id",
-            SWAP_ID,
-            "--receive-address",
-            MONERO_MAINNET_ADDRESS,
-        ];
+        let raw_ars = vec![BINARY_NAME, "--json", "resume", "--swap-id", SWAP_ID];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
         assert_eq!(
@@ -912,8 +901,6 @@ mod tests {
             "resume",
             "--swap-id",
             SWAP_ID,
-            "--receive-address",
-            MONERO_STAGENET_ADDRESS,
         ];
 
         let args = parse_args_and_apply_defaults(raw_ars).unwrap();
@@ -935,6 +922,7 @@ mod tests {
                     bitcoin_electrum_rpc_url: Url::from_str(DEFAULT_ELECTRUM_RPC_URL_TESTNET)
                         .unwrap(),
                     bitcoin_target_block: DEFAULT_BITCOIN_CONFIRMATION_TARGET_TESTNET,
+                    bitcoin_change_address: BITCOIN_TESTNET_ADDRESS.parse().unwrap(),
                     monero_receive_address: monero::Address::from_str(MONERO_STAGENET_ADDRESS)
                         .unwrap(),
                     monero_daemon_address: DEFAULT_MONERO_DAEMON_ADDRESS_STAGENET.to_string(),
@@ -953,6 +941,7 @@ mod tests {
                     seller: Multiaddr::from_str(MULTI_ADDRESS).unwrap(),
                     bitcoin_electrum_rpc_url: Url::from_str(DEFAULT_ELECTRUM_RPC_URL).unwrap(),
                     bitcoin_target_block: DEFAULT_BITCOIN_CONFIRMATION_TARGET,
+                    bitcoin_change_address: BITCOIN_MAINNET_ADDRESS.parse().unwrap(),
                     monero_receive_address: monero::Address::from_str(MONERO_MAINNET_ADDRESS)
                         .unwrap(),
                     monero_daemon_address: DEFAULT_MONERO_DAEMON_ADDRESS.to_string(),
@@ -972,8 +961,6 @@ mod tests {
                     bitcoin_electrum_rpc_url: Url::from_str(DEFAULT_ELECTRUM_RPC_URL_TESTNET)
                         .unwrap(),
                     bitcoin_target_block: DEFAULT_BITCOIN_CONFIRMATION_TARGET_TESTNET,
-                    monero_receive_address: monero::Address::from_str(MONERO_STAGENET_ADDRESS)
-                        .unwrap(),
                     monero_daemon_address: DEFAULT_MONERO_DAEMON_ADDRESS_STAGENET.to_string(),
                     tor_socks5_port: DEFAULT_SOCKS5_PORT,
                 },
@@ -990,8 +977,6 @@ mod tests {
                     swap_id: Uuid::from_str(SWAP_ID).unwrap(),
                     bitcoin_electrum_rpc_url: Url::from_str(DEFAULT_ELECTRUM_RPC_URL).unwrap(),
                     bitcoin_target_block: DEFAULT_BITCOIN_CONFIRMATION_TARGET,
-                    monero_receive_address: monero::Address::from_str(MONERO_MAINNET_ADDRESS)
-                        .unwrap(),
                     monero_daemon_address: DEFAULT_MONERO_DAEMON_ADDRESS.to_string(),
                     tor_socks5_port: DEFAULT_SOCKS5_PORT,
                 },

swap/src/database.rs

@@ -69,6 +69,7 @@ pub struct Database {
     swaps: sled::Tree,
     peers: sled::Tree,
     addresses: sled::Tree,
+    monero_addresses: sled::Tree,
 }
 
 impl Database {
@@ -81,11 +82,13 @@ impl Database {
         let swaps = db.open_tree("swaps")?;
         let peers = db.open_tree("peers")?;
         let addresses = db.open_tree("addresses")?;
+        let monero_addresses = db.open_tree("monero_addresses")?;
 
         Ok(Database {
             swaps,
             peers,
             addresses,
+            monero_addresses,
         })
     }
 
@@ -116,6 +119,39 @@ impl Database {
         Ok(PeerId::from_str(peer_id.as_str())?)
     }
 
+    pub async fn insert_monero_address(
+        &self,
+        swap_id: Uuid,
+        address: monero::Address,
+    ) -> Result<()> {
+        let key = swap_id.as_bytes();
+        let value = serialize(&address)?;
+
+        self.monero_addresses.insert(key, value)?;
+
+        self.monero_addresses
+            .flush_async()
+            .await
+            .map(|_| ())
+            .context("Could not flush db")
+    }
+
+    pub fn get_monero_address(&self, swap_id: Uuid) -> Result<monero::Address> {
+        let encoded = self
+            .monero_addresses
+            .get(swap_id.as_bytes())?
+            .ok_or_else(|| {
+                anyhow!(
+                    "No Monero address found for swap id {} in database",
+                    swap_id
+                )
+            })?;
+
+        let monero_address = deserialize(&encoded)?;
+
+        Ok(monero_address)
+    }
+
     pub async fn insert_address(&self, peer_id: PeerId, address: Multiaddr) -> Result<()> {
         let key = peer_id.to_bytes();
 
@@ -425,4 +461,17 @@ mod tests {
 
         Ok(())
     }
+
+    #[tokio::test]
+    async fn save_and_load_monero_address() -> Result<()> {
+        let db_dir = tempfile::tempdir()?;
+        let swap_id = Uuid::new_v4();
+
+        Database::open(db_dir.path())?.insert_monero_address(swap_id, "53gEuGZUhP9JMEBZoGaFNzhwEgiG7hwQdMCqFxiyiTeFPmkbt1mAoNybEUvYBKHcnrSgxnVWgZsTvRBaHBNXPa8tHiCU51a".parse()?).await?;
+        let loaded_monero_address = Database::open(db_dir.path())?.get_monero_address(swap_id)?;
+
+        assert_eq!(loaded_monero_address.to_string(), "53gEuGZUhP9JMEBZoGaFNzhwEgiG7hwQdMCqFxiyiTeFPmkbt1mAoNybEUvYBKHcnrSgxnVWgZsTvRBaHBNXPa8tHiCU51a");
+
+        Ok(())
+    }
 }

swap/src/database/bob.rs

@@ -3,13 +3,17 @@ use crate::protocol::bob;
 use crate::protocol::bob::BobState;
 use monero_rpc::wallet::BlockHeight;
 use serde::{Deserialize, Serialize};
+use serde_with::{serde_as, DisplayFromStr};
 use std::fmt;
 
+#[serde_as]
 #[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
 pub enum Bob {
     Started {
         #[serde(with = "::bitcoin::util::amount::serde::as_sat")]
         btc_amount: bitcoin::Amount,
+        #[serde_as(as = "DisplayFromStr")]
+        change_address: bitcoin::Address,
     },
     ExecutionSetupDone {
         state2: bob::State2,
@@ -45,7 +49,13 @@ pub enum BobEndState {
 impl From<BobState> for Bob {
     fn from(bob_state: BobState) -> Self {
         match bob_state {
-            BobState::Started { btc_amount } => Bob::Started { btc_amount },
+            BobState::Started {
+                btc_amount,
+                change_address,
+            } => Bob::Started {
+                btc_amount,
+                change_address,
+            },
             BobState::SwapSetupCompleted(state2) => Bob::ExecutionSetupDone { state2 },
             BobState::BtcLocked(state3) => Bob::BtcLocked { state3 },
             BobState::XmrLockProofReceived {
@@ -77,7 +87,13 @@ impl From<BobState> for Bob {
 impl From<Bob> for BobState {
     fn from(db_state: Bob) -> Self {
         match db_state {
-            Bob::Started { btc_amount } => BobState::Started { btc_amount },
+            Bob::Started {
+                btc_amount,
+                change_address,
+            } => BobState::Started {
+                btc_amount,
+                change_address,
+            },
             Bob::ExecutionSetupDone { state2 } => BobState::SwapSetupCompleted(state2),
             Bob::BtcLocked { state3 } => BobState::BtcLocked(state3),
             Bob::XmrLockProofReceived {

swap/src/protocol/bob.rs

@@ -20,7 +20,7 @@ pub struct Swap {
     pub monero_wallet: Arc<monero::Wallet>,
     pub env_config: env::Config,
     pub id: Uuid,
-    pub receive_monero_address: monero::Address,
+    pub monero_receive_address: monero::Address,
 }
 
 impl Swap {
@@ -32,21 +32,26 @@ impl Swap {
         monero_wallet: Arc<monero::Wallet>,
         env_config: env::Config,
         event_loop_handle: cli::EventLoopHandle,
-        receive_monero_address: monero::Address,
+        monero_receive_address: monero::Address,
+        bitcoin_change_address: bitcoin::Address,
         btc_amount: bitcoin::Amount,
     ) -> Self {
         Self {
-            state: BobState::Started { btc_amount },
+            state: BobState::Started {
+                btc_amount,
+                change_address: bitcoin_change_address,
+            },
             event_loop_handle,
             db,
             bitcoin_wallet,
             monero_wallet,
             env_config,
             id,
-            receive_monero_address,
+            monero_receive_address,
         }
     }
 
+    #[allow(clippy::too_many_arguments)]
     pub fn from_db(
         db: Database,
         id: Uuid,
@@ -54,7 +59,7 @@ impl Swap {
         monero_wallet: Arc<monero::Wallet>,
         env_config: env::Config,
         event_loop_handle: cli::EventLoopHandle,
-        receive_monero_address: monero::Address,
+        monero_receive_address: monero::Address,
     ) -> Result<Self> {
         let state = db.get_state(id)?.try_into_bob()?.into();
 
@@ -66,7 +71,7 @@ impl Swap {
             monero_wallet,
             env_config,
             id,
-            receive_monero_address,
+            monero_receive_address,
         })
     }
 }

swap/src/protocol/bob/state.rs

@@ -25,6 +25,7 @@ use uuid::Uuid;
 pub enum BobState {
     Started {
         btc_amount: bitcoin::Amount,
+        change_address: bitcoin::Address,
     },
     SwapSetupCompleted(State2),
     BtcLocked(State3),
@@ -169,7 +170,14 @@ impl State0 {
             bail!("Alice's dleq proof doesn't verify")
         }
 
-        let tx_lock = bitcoin::TxLock::new(wallet, self.btc, msg.A, self.b.public()).await?;
+        let tx_lock = bitcoin::TxLock::new(
+            wallet,
+            self.btc,
+            msg.A,
+            self.b.public(),
+            self.refund_address.clone(),
+        )
+        .await?;
         let v = msg.v_a + self.v_b;
 
         Ok(State1 {

swap/src/protocol/bob/swap.rs

@@ -37,7 +37,7 @@ pub async fn run_until(
             &mut swap.event_loop_handle,
             swap.bitcoin_wallet.as_ref(),
             swap.monero_wallet.as_ref(),
-            swap.receive_monero_address,
+            swap.monero_receive_address,
         )
         .await?;
 
@@ -56,13 +56,15 @@ async fn next_state(
     event_loop_handle: &mut EventLoopHandle,
     bitcoin_wallet: &bitcoin::Wallet,
     monero_wallet: &monero::Wallet,
-    receive_monero_address: monero::Address,
+    monero_receive_address: monero::Address,
 ) -> Result<BobState> {
     tracing::trace!(%state, "Advancing state");
 
     Ok(match state {
-        BobState::Started { btc_amount } => {
-            let bitcoin_refund_address = bitcoin_wallet.new_address().await?;
+        BobState::Started {
+            btc_amount,
+            change_address,
+        } => {
             let tx_refund_fee = bitcoin_wallet
                 .estimate_fee(TxRefund::weight(), btc_amount)
                 .await?;
@@ -76,7 +78,7 @@ async fn next_state(
                     btc: btc_amount,
                     tx_refund_fee,
                     tx_cancel_fee,
-                    bitcoin_refund_address,
+                    bitcoin_refund_address: change_address,
                 })
                 .await?;
 
@@ -224,10 +226,10 @@ async fn next_state(
             // Ensure that the generated wallet is synced so we have a proper balance
             monero_wallet.refresh().await?;
             // Sweep (transfer all funds) to the given address
-            let tx_hashes = monero_wallet.sweep_all(receive_monero_address).await?;
+            let tx_hashes = monero_wallet.sweep_all(monero_receive_address).await?;
 
             for tx_hash in tx_hashes {
-                tracing::info!(%receive_monero_address, txid=%tx_hash.0, "Sent XMR to");
+                tracing::info!(%monero_receive_address, txid=%tx_hash.0, "Sent XMR to");
             }
 
             BobState::XmrRedeemed {

swap/tests/harness/mod.rs

@@ -434,6 +434,7 @@ impl BobParams {
             self.env_config,
             handle,
             self.monero_wallet.get_main_address(),
+            self.bitcoin_wallet.new_address().await?,
             btc_amount,
         );