fix: Explicitly deny multipath keys

Although there is *some* code to handle multipath keys inside bdk,
it's all untested, and from a few quick tests it
seems that it's pretty easy to find buggy edge cases.
Better to deny multipath descs for now, and revisit the
decision once we work on supporting multidescriptor wallets.

diff --git a/src/descriptor/error.rs b/src/descriptor/error.rs
index 417a43dd3eced4109ef43e7b4a479598b9a15646..aed2d95b3dda2add5dfcbddff9cbdf8c4e88c19d 100644 (file)
--- a/src/descriptor/error.rs
+++ b/src/descriptor/error.rs
@@ -20,6 +20,8 @@ pub enum Error {
     InvalidDescriptorChecksum,
     /// The descriptor contains hardened derivation steps on public extended keys
     HardenedDerivationXpub,
+    /// The descriptor contains multipath keys
+    MultiPath,
 
     /// Error thrown while working with [`keys`](crate::keys)
     Key(crate::keys::KeyError),
@@ -62,6 +64,10 @@ impl std::fmt::Display for Error {
                 f,
                 "The descriptor contains hardened derivation steps on public extended keys"
             ),
+            Self::MultiPath => write!(
+                f,
+                "The descriptor contains multipath keys, which are not supported yet"
+            ),
             Self::Key(err) => write!(f, "Key error: {}", err),
             Self::Policy(err) => write!(f, "Policy error: {}", err),
             Self::InvalidDescriptorCharacter(char) => {

diff --git a/src/descriptor/mod.rs b/src/descriptor/mod.rs
index 5b97a3ed90af53fa24e9c57fa25ed3283d224692..1ee43e306f757bd1781d9f90d12a2b82395697f5 100644 (file)
--- a/src/descriptor/mod.rs
+++ b/src/descriptor/mod.rs
@@ -306,6 +306,10 @@ pub(crate) fn into_wallet_descriptor_checked<T: IntoWalletDescriptor>(
         return Err(DescriptorError::HardenedDerivationXpub);
     }
 
+    if descriptor.is_multipath() {
+        return Err(DescriptorError::MultiPath);
+    }
+
     // Run miniscript's sanity check, which will look for duplicated keys and other potential
     // issues
     descriptor.sanity_check()?;
@@ -862,6 +866,12 @@ mod test {
 
         assert_matches!(result, Err(DescriptorError::HardenedDerivationXpub));
 
+        let descriptor = "wpkh(tpubD6NzVbkrYhZ4XHndKkuB8FifXm8r5FQHwrN6oZuWCz13qb93rtgKvD4PQsqC4HP4yhV3tA2fqr2RbY5mNXfM7RxXUoeABoDtsFUq2zJq6YK/<0;1>/*)";
+        let result = into_wallet_descriptor_checked(descriptor, &secp, Network::Testnet);
+
+        assert_matches!(result, Err(DescriptorError::MultiPath));
+
+        // repeated pubkeys
         let descriptor = "wsh(multi(2,tpubD6NzVbkrYhZ4XHndKkuB8FifXm8r5FQHwrN6oZuWCz13qb93rtgKvD4PQsqC4HP4yhV3tA2fqr2RbY5mNXfM7RxXUoeABoDtsFUq2zJq6YK/0/*,tpubD6NzVbkrYhZ4XHndKkuB8FifXm8r5FQHwrN6oZuWCz13qb93rtgKvD4PQsqC4HP4yhV3tA2fqr2RbY5mNXfM7RxXUoeABoDtsFUq2zJq6YK/0/*))";
         let result = into_wallet_descriptor_checked(descriptor, &secp, Network::Testnet);