Merge pull request #110 from pythcoiner/issue_109

ledger: fix change detection logic in Ledger::display_address()

Author: edouardparis

cli/src/lib.rs

@@ -68,7 +68,7 @@ pub mod command {
                     {
                         if let Ok((device, _)) = device.wait_confirm().await {
                             let mut bb02 = BitBox02::from(device).with_network(network);
-                            if let Some(ref policy) = wallet.as_ref().map(|w| w.policy).flatten() {
+                            if let Some(policy) = wallet.as_ref().and_then(|w| w.policy) {
                                 bb02 = bb02.with_policy(policy)?;
                             }
                             hws.push(bb02.into());

src/ledger.rs

@@ -26,7 +26,10 @@ use ledger_bitcoin_client::{
     WalletPolicy, WalletPubKey,
 };
 
-use crate::{parse_version, utils, AddressScript, DeviceKind, Error as HWIError, HWI};
+use crate::{
+    parse_version, utils, AddressScript, DeviceKind, Error as HWIError, CHANGE_INDEX, HWI,
+    RECV_INDEX,
+};
 
 pub use hidapi::{DeviceInfo, HidApi};
 pub use ledger_bitcoin_client::async_client::Transport;
@@ -111,11 +114,14 @@ impl<T: Transport + Sync + Send> HWI for Ledger<T> {
                 let wallet =
                     WalletPolicy::new("".into(), WalletVersion::V2, descriptor_template, keys);
 
+                if ![RECV_INDEX, CHANGE_INDEX].contains(&normal_children[0]) {
+                    return Err(HWIError::Bip86ChangeIndex);
+                }
                 self.client
                     .get_wallet_address(
                         &wallet,
                         None,
-                        normal_children[0] == ChildNumber::from_normal_idx(0).unwrap(),
+                        normal_children[0] == CHANGE_INDEX,
                         normal_children[1].into(),
                         true,
                     )

src/lib.rs

@@ -13,12 +13,15 @@ pub mod utils;
 
 use async_trait::async_trait;
 use bitcoin::{
-    bip32::{DerivationPath, Fingerprint, Xpub},
+    bip32::{ChildNumber, DerivationPath, Fingerprint, Xpub},
     psbt::Psbt,
 };
 
 use std::{cmp::Ordering, fmt::Debug, str::FromStr};
 
+const RECV_INDEX: ChildNumber = ChildNumber::Normal { index: 0 };
+const CHANGE_INDEX: ChildNumber = ChildNumber::Normal { index: 1 };
+
 #[derive(Debug, Clone)]
 pub enum Error {
     ParsingPolicy(bip389::ParseError),
@@ -34,6 +37,7 @@ pub enum Error {
     Unexpected(&'static str),
     UserRefused,
     NetworkMismatch,
+    Bip86ChangeIndex,
 }
 
 impl std::fmt::Display for Error {
@@ -52,6 +56,9 @@ impl std::fmt::Display for Error {
             Error::Unexpected(e) => write!(f, "{}", e),
             Error::UserRefused => write!(f, "User refused operation"),
             Error::NetworkMismatch => write!(f, "Device network is different"),
+            Error::Bip86ChangeIndex => {
+                write!(f, "Ledger devices only accept 0 or 1 as`change` index value for BIP86 derivation path")
+            }
         }
     }
 }