feat(psbt): allow use of non-btc nonWitnessUtxos

Enables extension of Psbt to support other chains.

Issue: BG-55848

Author: reardencode

src/psbt.d.ts

@@ -56,6 +56,7 @@ export declare class Psbt {
     static fromBase64(data: string, opts?: PsbtOptsOptional): Psbt;
     static fromHex(data: string, opts?: PsbtOptsOptional): Psbt;
     static fromBuffer(buffer: Buffer, opts?: PsbtOptsOptional): Psbt;
+    protected static transactionFromBuffer(buffer: Buffer, _network: Network): Transaction<bigint>;
     private __CACHE;
     private opts;
     constructor(opts?: PsbtOptsOptional, data?: PsbtBase);

src/psbt.js

@@ -78,6 +78,8 @@ class Psbt {
       // We will disable exporting the Psbt when unsafe sign is active.
       // because it is not BIP174 compliant.
       __UNSAFE_SIGN_NONSEGWIT: false,
+      __TX_FROM_BUFFER: buf =>
+        this.constructor.transactionFromBuffer(buf, this.opts.network),
     };
     if (this.data.inputs.length === 0) this.setVersion(2);
     // Make data hidden when enumerating
@@ -103,6 +105,9 @@ class Psbt {
     checkTxForDupeIns(psbt.__CACHE.__TX, psbt.__CACHE);
     return psbt;
   }
+  static transactionFromBuffer(buffer, _network) {
+    return transaction_1.Transaction.fromBuffer(buffer, undefined, 'bigint');
+  }
   get inputCount() {
     return this.data.inputs.length;
   }
@@ -1219,11 +1224,7 @@ function witnessStackToScriptWitness(witness) {
 }
 function addNonWitnessTxCache(cache, input, inputIndex) {
   cache.__NON_WITNESS_UTXO_BUF_CACHE[inputIndex] = input.nonWitnessUtxo;
-  const tx = transaction_1.Transaction.fromBuffer(
-    input.nonWitnessUtxo,
-    undefined,
-    'bigint',
-  );
+  const tx = cache.__TX_FROM_BUFFER(input.nonWitnessUtxo);
   cache.__NON_WITNESS_UTXO_TX_CACHE[inputIndex] = tx;
   const self = cache;
   const selfIndex = inputIndex;

ts_src/psbt.ts

@@ -114,6 +114,13 @@ export class Psbt {
     return psbt;
   }
 
+  protected static transactionFromBuffer(
+    buffer: Buffer,
+    _network: Network,
+  ): Transaction<bigint> {
+    return Transaction.fromBuffer<bigint>(buffer, undefined, 'bigint');
+  }
+
   private __CACHE: PsbtCache;
   private opts: PsbtOpts;
 
@@ -137,6 +144,11 @@ export class Psbt {
       // We will disable exporting the Psbt when unsafe sign is active.
       // because it is not BIP174 compliant.
       __UNSAFE_SIGN_NONSEGWIT: false,
+      __TX_FROM_BUFFER: buf =>
+        (this.constructor as typeof Psbt).transactionFromBuffer(
+          buf,
+          this.opts.network,
+        ),
     };
     if (this.data.inputs.length === 0) this.setVersion(2);
 
@@ -752,6 +764,7 @@ interface PsbtCache {
   __FEE?: bigint;
   __EXTRACTED_TX?: Transaction<bigint>;
   __UNSAFE_SIGN_NONSEGWIT: boolean;
+  __TX_FROM_BUFFER: (buf: Buffer) => Transaction<bigint>;
 }
 
 interface PsbtOptsOptional {
@@ -1590,11 +1603,7 @@ function addNonWitnessTxCache(
 ): void {
   cache.__NON_WITNESS_UTXO_BUF_CACHE[inputIndex] = input.nonWitnessUtxo!;
 
-  const tx = Transaction.fromBuffer<bigint>(
-    input.nonWitnessUtxo!,
-    undefined,
-    'bigint',
-  );
+  const tx = cache.__TX_FROM_BUFFER(input.nonWitnessUtxo!);
   cache.__NON_WITNESS_UTXO_TX_CACHE[inputIndex] = tx;
 
   const self = cache;