Add subcommand to print internal bitcoin wallet descriptor

Example:

 cargo run --package swap --bin swap -- export-bitcoin-wallet

{"descriptor":"wpkh(xprv9s21ZrQH143K2q85eUf2ppCtti2Zar6aDCW5dCC5DG9VvutJ3cpe3Qf9wZpQeraNf9JEuGem1RyJZQMEWCN2DpWyL5WbsvmSW6wbL7Jq53H/84'/0'/0'/0/*)","blockheight":0,"label":"cli-bitcoin"}

CHANGELOG.md

@@ -50,6 +50,8 @@ It is possible to migrate critical data from the old db to the sqlite but there
 - Added a `disable-timestamp` flag to the ASB that disables timestamps from logs.
 - A `config` subcommand that prints the current configuration including the data directory location.
   This feature should alleviate difficulties users were having when finding where xmr-btc-swap was storing data.
+- Added `export-bitcoin-wallet` subcommand to the CLI and ASB, to print the internal bitcoin wallet descriptor.
+  This will allow users to transact and monitor using external wallets.
 
 ## [0.8.3] - 2021-09-03
 

swap/src/asb/command.rs

@@ -74,6 +74,15 @@ where
             env_config: env_config(testnet),
             cmd: Command::Config,
         },
+        RawCommand::ExportBitcoinWallet => Arguments {
+            testnet,
+            json,
+            sled,
+            disable_timestamp,
+            config_path: config_path(config, testnet)?,
+            env_config: env_config(testnet),
+            cmd: Command::ExportBitcoinWallet,
+        },
         RawCommand::ManualRecovery(ManualRecovery::Redeem {
             redeem_params: RecoverCommandParams { swap_id },
             do_not_await_finality,
@@ -222,6 +231,7 @@ pub enum Command {
     SafelyAbort {
         swap_id: Uuid,
     },
+    ExportBitcoinWallet,
 }
 
 #[derive(structopt::StructOpt, Debug)]
@@ -296,6 +306,8 @@ pub enum RawCommand {
         about = "Prints the Bitcoin and Monero balance. Requires the monero-wallet-rpc to be running."
     )]
     Balance,
+    #[structopt(about = "Print the internal bitcoin wallet descriptor.")]
+    ExportBitcoinWallet,
     #[structopt(about = "Contains sub-commands for recovering a swap manually.")]
     ManualRecovery(ManualRecovery),
 }

swap/src/bin/asb.rs

@@ -301,6 +301,11 @@ async fn main() -> Result<()> {
 
             tracing::info!("Redeem transaction successfully published with id {}", txid);
         }
+        Command::ExportBitcoinWallet => {
+            let bitcoin_wallet = init_bitcoin_wallet(&config, &seed, env_config).await?;
+            let wallet_export = bitcoin_wallet.wallet_export("asb").await?;
+            println!("{}", wallet_export.to_string())
+        }
     }
 
     Ok(())

swap/src/bin/swap.rs

@@ -409,6 +409,23 @@ async fn main() -> Result<()> {
                 println!("{}", table);
             }
         }
+        Command::ExportBitcoinWallet {
+            bitcoin_electrum_rpc_url,
+            bitcoin_target_block,
+        } => {
+            let seed = Seed::from_file_or_generate(data_dir.as_path())
+                .context("Failed to read in seed file")?;
+            let bitcoin_wallet = init_bitcoin_wallet(
+                bitcoin_electrum_rpc_url,
+                &seed,
+                data_dir.clone(),
+                env_config,
+                bitcoin_target_block,
+            )
+            .await?;
+            let wallet_export = bitcoin_wallet.wallet_export("cli").await?;
+            println!("{}", wallet_export.to_string())
+        }
     };
     Ok(())
 }

swap/src/bitcoin/wallet.rs

@@ -9,6 +9,7 @@ use bdk::database::BatchDatabase;
 use bdk::descriptor::Segwitv0;
 use bdk::electrum_client::{ElectrumApi, GetHistoryRes};
 use bdk::keys::DerivableKey;
+use bdk::wallet::export::WalletExport;
 use bdk::wallet::AddressIndex;
 use bdk::{FeeRate, KeychainKind, SignOptions};
 use bitcoin::{Network, Script};
@@ -174,6 +175,18 @@ impl Wallet {
 
         sub
     }
+
+    pub async fn wallet_export(&self, role: &str) -> Result<WalletExport> {
+        let wallet = self.wallet.lock().await;
+        match bdk::wallet::export::WalletExport::export_wallet(
+            &wallet,
+            &format!("{}-{}", role, self.network),
+            true,
+        ) {
+            Ok(wallet_export) => Ok(wallet_export),
+            Err(err_msg) => Err(anyhow::Error::msg(err_msg)),
+        }
+    }
 }
 
 fn print_status_change(txid: Txid, old: Option<ScriptStatus>, new: ScriptStatus) -> ScriptStatus {

swap/src/cli/command.rs

@@ -239,6 +239,22 @@ where
                 tor_socks5_port,
             },
         },
+        RawCommand::ExportBitcoinWallet { bitcoin } => {
+            let (bitcoin_electrum_rpc_url, bitcoin_target_block) =
+                bitcoin.apply_defaults(is_testnet)?;
+
+            Arguments {
+                env_config: env_config_from(is_testnet),
+                debug,
+                json,
+                sled,
+                data_dir: data::data_dir_from(data, is_testnet)?,
+                cmd: Command::ExportBitcoinWallet {
+                    bitcoin_electrum_rpc_url,
+                    bitcoin_target_block,
+                },
+            }
+        }
     };
 
     Ok(ParseResult::Arguments(arguments))
@@ -289,6 +305,10 @@ pub enum Command {
         namespace: XmrBtcNamespace,
         tor_socks5_port: u16,
     },
+    ExportBitcoinWallet {
+        bitcoin_electrum_rpc_url: Url,
+        bitcoin_target_block: usize,
+    },
 }
 
 #[derive(structopt::StructOpt, Debug)]
@@ -427,6 +447,11 @@ enum RawCommand {
         #[structopt(flatten)]
         tor: Tor,
     },
+    /// Print the internal bitcoin wallet descriptor
+    ExportBitcoinWallet {
+        #[structopt(flatten)]
+        bitcoin: Bitcoin,
+    },
 }
 
 #[derive(structopt::StructOpt, Debug)]