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/crates/bdk/src/descriptor/error.rs b/crates/bdk/src/descriptor/error.rs
index 8731b5bfda270b022a2b0e24f99492b07e40d5e1..07a874efed93a54a2e5feb81a250b208be004ef1 100644 (file)
--- a/crates/bdk/src/descriptor/error.rs
+++ b/crates/bdk/src/descriptor/error.rs
@@ -22,6 +22,8 @@ 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),
@@ -64,6 +66,10 @@ impl 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/crates/bdk/src/descriptor/mod.rs b/crates/bdk/src/descriptor/mod.rs
index e139f7bd8b477644cf5bb4d0bb1708a7385b868c..d5c3415f7bf28d0fbce55d7c365d5c9023a413b7 100644 (file)
--- a/crates/bdk/src/descriptor/mod.rs
+++ b/crates/bdk/src/descriptor/mod.rs
@@ -308,6 +308,10 @@ 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()?;
@@ -865,6 +869,12 @@ 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);