psbt: validate that non_witness_utxo txids match the input txids

This requires updating a couple serde test vectors -- we are tightening
validation so that some existing serde-serialized PSBTs no longer
deserialize. I believe this is the correct thing to do.

Author: apoelstra

bitcoin/src/psbt/mod.rs

@@ -1667,6 +1667,7 @@ mod tests {
             },
             unsigned_tx: {
                 let mut unsigned = tx.clone();
+                unsigned.input[0].previous_output.txid = tx.compute_txid();
                 unsigned.input[0].script_sig = ScriptBuf::new();
                 unsigned.input[0].witness = Witness::default();
                 unsigned

bitcoin/src/psbt/serialize.rs

@@ -103,8 +103,20 @@ impl Psbt {
 
             let mut inputs: Vec<Input> = Vec::with_capacity(inputs_len);
 
-            for _ in 0..inputs_len {
-                inputs.push(Input::decode(r)?);
+            for i in 0..inputs_len {
+                let input = Input::decode(r)?;
+                if let Some(ref tx) = input.non_witness_utxo {
+                    let input_outpoint = global.unsigned_tx.input[i].previous_output;
+                    let txid = tx.compute_txid();
+                    if txid != input_outpoint.txid {
+                        return Err(Error::IncorrectNonWitnessUtxo {
+                            index: i,
+                            input_outpoint,
+                            non_witness_utxo_txid: txid,
+                        });
+                    }
+                }
+                inputs.push(input);
             }
 
             inputs

bitcoin/tests/data/serde/psbt_base64.json

@@ -1 +1 @@
-"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"
+"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"

bitcoin/tests/data/serde/psbt_bincode

@@ -285,6 +285,7 @@ fn serde_regression_psbt() {
         },
         unsigned_tx: {
             let mut unsigned = tx.clone();
+            unsigned.input[0].previous_output.txid = tx.compute_txid();
             unsigned.input[0].script_sig = ScriptBuf::new();
             unsigned.input[0].witness = Witness::default();
             unsigned