Merge #339: Add PsbtInputExt::update_with_descriptor

f40dc83 fixup! Add find_derivation_index_for_spk (LLFourn)
3374e11 fixup! Add segwit_version to DescriptorType (LLFourn)
e85b99c Add segwit_version to DescriptorType (LLFourn)
cb0dd48 Add PsbtInputExt::update_with_descriptor (LLFourn)
f3198dc Add find_derivation_index_for_spk (LLFourn)

Pull request description:

  Fixes #335

  This populates all relevant fields in a PSBT input according to a descriptor. Includes previously not yet implemented logic for populating `bip32_derivation` and `tap_key_origins`. Also optionally checks the `witness_utxo` and `non_witness_utxo`.

  I renamed `PsbtExt::update_desc` to `PsbtExt::update_inp_with_descriptor` which calls `update_with_descriptor`
  internally but retrieves the vout for the input for the `non_witness_utxo` check automatically. I removed the derivation range functionality because it didn't feel useful (and if it is then it probably belongs in a separate function). Let me know if you want me to add it back where it was or to provide an additional utility function to find which index a script pubkey was derived from.

Top commit has no ACKs.

Tree-SHA512: 03a89a0aaaa3e3ef906537101e364fbbc8fc925872dbd8345e405383d307abbed5d6155967e34bae1b10451a170a6b1339ad507abf4943f80a2f5a6513b87783

Author: sanket1729

integration_test/src/test_desc.rs

@@ -13,7 +13,7 @@ use bitcoin::util::{psbt, sighash};
 use bitcoin::{self, Amount, OutPoint, SchnorrSig, Script, Transaction, TxIn, TxOut, Txid};
 use bitcoincore_rpc::{json, Client, RpcApi};
 use miniscript::miniscript::iter;
-use miniscript::psbt::PsbtExt;
+use miniscript::psbt::{PsbtInputExt, PsbtExt};
 use miniscript::{Descriptor, DescriptorTrait, Miniscript, ToPublicKey};
 use miniscript::{MiniscriptKey, ScriptContext};
 use std::collections::BTreeMap;
@@ -109,10 +109,10 @@ pub fn test_desc_satisfy(cl: &Client, testdata: &TestData, desc: &str) -> Witnes
         script_pubkey: addr.script_pubkey(),
     });
     let mut input = psbt::Input::default();
+    input.update_with_descriptor_unchecked(&desc).unwrap();
     input.witness_utxo = Some(witness_utxo.clone());
     psbt.inputs.push(input);
     psbt.outputs.push(psbt::Output::default());
-    psbt.update_desc(0, &desc, None).unwrap();
 
     // --------------------------------------------
     // Sign the transactions with all keys

src/descriptor/mod.rs

@@ -23,13 +23,15 @@
 //! these with BIP32 paths, pay-to-contract instructions, etc.
 //!
 
+use std::ops::Range;
 use std::{collections::HashMap, sync::Arc};
 use std::{
     fmt,
     str::{self, FromStr},
 };
 
 use bitcoin::blockdata::witness::Witness;
+use bitcoin::util::address::WitnessVersion;
 use bitcoin::{self, secp256k1, Script};
 
 use self::checksum::verify_checksum;
@@ -259,6 +261,22 @@ pub enum DescriptorType {
     Tr,
 }
 
+impl DescriptorType {
+    /// Returns the segwit version implied by the descriptor type.
+    ///
+    /// This will return `Some(WitnessVersion::V0)` whether it is "native" segwitv0 or "wrapped" p2sh segwit.
+    pub fn segwit_version(&self) -> Option<WitnessVersion> {
+        use self::DescriptorType::*;
+        match self {
+            Tr => Some(WitnessVersion::V1),
+            Wpkh | ShWpkh | Wsh | ShWsh | ShWshSortedMulti | WshSortedMulti => {
+                Some(WitnessVersion::V0)
+            }
+            Bare | Sh | Pkh | ShSortedMulti => None,
+        }
+    }
+}
+
 impl<Pk: MiniscriptKey> Descriptor<Pk> {
     // Keys
 
@@ -749,6 +767,31 @@ impl Descriptor<DescriptorPublicKey> {
 
         descriptor.to_string()
     }
+
+    /// Utility method for deriving the descriptor at each index in a range to find one matching
+    /// `script_pubkey`.
+    ///
+    /// If it finds a match then it returns the index it was derived at and the concrete
+    /// descriptor at that index. If the descriptor is non-derivable then it will simply check the
+    /// script pubkey against the descriptor and return it if it matches (in this case the index
+    /// returned will be meaningless).
+    pub fn find_derivation_index_for_spk<C: secp256k1::Verification>(
+        &self,
+        secp: &secp256k1::Secp256k1<C>,
+        script_pubkey: &Script,
+        range: Range<u32>,
+    ) -> Result<Option<(u32, Descriptor<bitcoin::PublicKey>)>, ConversionError> {
+        let range = if self.is_deriveable() { range } else { 0..1 };
+
+        for i in range {
+            let concrete = self.derived_descriptor(&secp, i)?;
+            if &concrete.script_pubkey() == script_pubkey {
+                return Ok(Some((i, concrete)));
+            }
+        }
+
+        Ok(None)
+    }
 }
 
 impl<Pk> expression::FromTree for Descriptor<Pk>
@@ -1736,4 +1779,31 @@ pk(03f28773c2d975288bc7d1d205c3748651b075fbc6610e58cddeeddf8f19405aa8))";
         Descriptor::<DescriptorPublicKey>::from_str(&format!("wsh(pk({}))", x_only_key))
             .unwrap_err();
     }
+
+    #[test]
+    fn test_find_derivation_index_for_spk() {
+        let secp = secp256k1::Secp256k1::verification_only();
+        let descriptor = Descriptor::from_str("tr([73c5da0a/86'/0'/0']xpub6BgBgsespWvERF3LHQu6CnqdvfEvtMcQjYrcRzx53QJjSxarj2afYWcLteoGVky7D3UKDP9QyrLprQ3VCECoY49yfdDEHGCtMMj92pReUsQ/0/*)").unwrap();
+        let script_at_0_1 = Script::from_str(
+            "5120a82f29944d65b86ae6b5e5cc75e294ead6c59391a1edc5e016e3498c67fc7bbb",
+        )
+        .unwrap();
+        let expected_concrete = Descriptor::from_str(
+            "tr(0283dfe85a3151d2517290da461fe2815591ef69f2b18a2ce63f01697a8b313145)",
+        )
+        .unwrap();
+
+        assert_eq!(
+            descriptor.find_derivation_index_for_spk(&secp, &script_at_0_1, 0..1),
+            Ok(None)
+        );
+        assert_eq!(
+            descriptor.find_derivation_index_for_spk(&secp, &script_at_0_1, 0..2),
+            Ok(Some((1, expected_concrete.clone())))
+        );
+        assert_eq!(
+            descriptor.find_derivation_index_for_spk(&secp, &script_at_0_1, 0..10),
+            Ok(Some((1, expected_concrete)))
+        );
+    }
 }