Introduce constructor for p2wpkh input pairs

Author: shinghim

payjoin-test-utils/src/lib.rs

@@ -303,3 +303,18 @@ pub static PARSED_PAYJOIN_PROPOSAL_WITH_SENDER_INFO: Lazy<Psbt> = Lazy::new(|| {
 pub const MULTIPARTY_ORIGINAL_PSBT_ONE: &str = "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";
 
 pub const MULTIPARTY_ORIGINAL_PSBT_TWO: &str = "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";
+
+/// sha256d of the empty string
+#[rustfmt::skip]
+pub const DUMMY32: [u8; 32] = [
+    0x5d, 0xf6, 0xe0, 0xe2, 0x76, 0x13, 0x59, 0xd3,
+    0x0a, 0x82, 0x75, 0x05, 0x8e, 0x29, 0x9f, 0xcc,
+    0x03, 0x81, 0x53, 0x45, 0x45, 0xf5, 0x5c, 0xf4,
+    0x3e, 0x41, 0x98, 0x3f, 0x5d, 0x4c, 0x94, 0x56,
+];
+/// hash160 of the empty string
+#[rustfmt::skip]
+pub const DUMMY20: [u8; 20] = [
+    0xb4, 0x72, 0xa2, 0x66, 0xd0, 0xbd, 0x89, 0xc1, 0x37, 0x06,
+    0xa4, 0x13, 0x2c, 0xcf, 0xb1, 0x6f, 0x7c, 0x3b, 0x9f, 0xcb,
+];

payjoin/src/psbt/mod.rs

@@ -217,7 +217,7 @@ impl InternalInputPair<'_> {
     }
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub(crate) enum PrevTxOutError {
     MissingUtxoInformation,
     IndexOutOfBounds { output_count: usize, index: u32 },
@@ -236,14 +236,15 @@ impl fmt::Display for PrevTxOutError {
 
 impl std::error::Error for PrevTxOutError {}
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub(crate) enum InternalPsbtInputError {
     PrevTxOut(PrevTxOutError),
     UnequalTxid,
     /// TxOut provided in `segwit_utxo` doesn't match the one in `non_segwit_utxo`
     SegWitTxOutMismatch,
     AddressType(AddressTypeError),
     NoRedeemScript,
+    InvalidP2wpkhScriptPubkey,
 }
 
 impl fmt::Display for InternalPsbtInputError {
@@ -254,6 +255,7 @@ impl fmt::Display for InternalPsbtInputError {
             Self::SegWitTxOutMismatch => write!(f, "transaction output provided in SegWit UTXO field doesn't match the one in non-SegWit UTXO field"),
             Self::AddressType(_) => write!(f, "invalid address type"),
             Self::NoRedeemScript => write!(f, "provided p2sh PSBT input is missing a redeem_script"),
+            Self::InvalidP2wpkhScriptPubkey => write!(f, "provided script pubkey is invalid for P2WPKH")
         }
     }
 }
@@ -266,6 +268,7 @@ impl std::error::Error for InternalPsbtInputError {
             Self::SegWitTxOutMismatch => None,
             Self::AddressType(error) => Some(error),
             Self::NoRedeemScript => None,
+            Self::InvalidP2wpkhScriptPubkey => None,
         }
     }
 }
@@ -278,7 +281,7 @@ impl From<AddressTypeError> for InternalPsbtInputError {
     fn from(value: AddressTypeError) -> Self { Self::AddressType(value) }
 }
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq)]
 pub struct PsbtInputError(InternalPsbtInputError);
 
 impl From<InternalPsbtInputError> for PsbtInputError {
@@ -309,7 +312,7 @@ impl std::error::Error for PsbtInputsError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { Some(&self.error) }
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub(crate) enum AddressTypeError {
     PrevTxOut(PrevTxOutError),
     InvalidScript(FromScriptError),

payjoin/src/receive/mod.rs

@@ -11,7 +11,7 @@
 
 use std::str::FromStr;
 
-use bitcoin::{psbt, AddressType, Psbt, TxIn, TxOut};
+use bitcoin::{psbt, AddressType, OutPoint, Psbt, TxIn, TxOut};
 pub(crate) use error::InternalPayloadError;
 pub use error::{
     Error, InputContributionError, JsonReply, OutputSubstitutionError, PayloadError,
@@ -58,6 +58,30 @@ impl InputPair {
         Ok(input_pair)
     }
 
+    /// Constructs a new ['InputPair'] for spending a native SegWit P2WPKH output
+    pub fn new_p2wpkh(txout: TxOut, outpoint: OutPoint) -> Result<Self, PsbtInputError> {
+        if !txout.script_pubkey.is_p2wpkh() {
+            return Err(InternalPsbtInputError::InvalidP2wpkhScriptPubkey.into());
+        }
+
+        let txin = TxIn {
+            previous_output: OutPoint { txid: outpoint.txid, vout: outpoint.vout },
+            script_sig: Default::default(),
+            sequence: Default::default(),
+            witness: Default::default(),
+        };
+
+        let psbtin = psbt::Input {
+            witness_utxo: Some(TxOut { value: txout.value, script_pubkey: txout.script_pubkey }),
+            ..psbt::Input::default()
+        };
+        let input_pair = Self { txin, psbtin };
+        let raw = InternalInputPair::from(&input_pair);
+        raw.validate_utxo()?;
+
+        Ok(input_pair)
+    }
+
     pub(crate) fn previous_txout(&self) -> TxOut {
         InternalInputPair::from(self)
             .previous_txout()
@@ -88,3 +112,35 @@ pub(crate) fn parse_payload(
 
     Ok((psbt, params))
 }
+
+#[cfg(test)]
+mod tests {
+    use bitcoin::hashes::Hash;
+    use bitcoin::key::WPubkeyHash;
+    use bitcoin::{Amount, ScriptBuf, ScriptHash, Txid};
+    use payjoin_test_utils::{DUMMY20, DUMMY32};
+
+    use super::*;
+    use crate::psbt::InternalPsbtInputError::InvalidP2wpkhScriptPubkey;
+
+    #[test]
+    fn create_p2wpkh_input_pair() {
+        let outpoint = OutPoint { txid: Txid::from_byte_array(DUMMY32), vout: 31 };
+        let p2wpkh_txout = TxOut {
+            value: Amount::from_sat(12345),
+            script_pubkey: ScriptBuf::new_p2wpkh(&WPubkeyHash::from_byte_array(DUMMY20)),
+        };
+        let p2wpkh_pair = InputPair::new_p2wpkh(p2wpkh_txout.clone(), outpoint).unwrap();
+        assert_eq!(p2wpkh_pair.txin.previous_output, outpoint);
+        assert_eq!(p2wpkh_pair.psbtin.witness_utxo.unwrap(), p2wpkh_txout);
+
+        let p2sh_txout = TxOut {
+            value: Default::default(),
+            script_pubkey: ScriptBuf::new_p2sh(&ScriptHash::all_zeros()),
+        };
+        assert_eq!(
+            InputPair::new_p2wpkh(p2sh_txout, outpoint).err().unwrap(),
+            PsbtInputError::from(InvalidP2wpkhScriptPubkey)
+        )
+    }
+}