psbt: add a flags argument to psbt_get_input_signature_hash for future use

Author: jgriffiths

include/wally.hpp

@@ -988,8 +988,8 @@ inline int psbt_get_input_scriptcode_len(const PSBT& psbt, size_t index, const S
 }
 
 template <class PSBT, class TX, class SCRIPT, class BYTES_OUT>
-inline int psbt_get_input_signature_hash(const PSBT& psbt, size_t index, const TX& tx, const SCRIPT& script, BYTES_OUT& bytes_out) {
-    int ret = ::wally_psbt_get_input_signature_hash(detail::get_p(psbt), index, detail::get_p(tx), script.data(), script.size(), bytes_out.data(), bytes_out.size());
+inline int psbt_get_input_signature_hash(const PSBT& psbt, size_t index, const TX& tx, const SCRIPT& script, uint32_t flags, BYTES_OUT& bytes_out) {
+    int ret = ::wally_psbt_get_input_signature_hash(detail::get_p(psbt), index, detail::get_p(tx), script.data(), script.size(), flags, bytes_out.data(), bytes_out.size());
     return ret;
 }
 

include/wally_psbt.h

@@ -2115,13 +2115,14 @@ WALLY_CORE_API int wally_psbt_get_input_scriptcode(
     size_t *written);
 
 /**
- * Create a BTC transaction for signing a PSBT input and return its hash.
+ * Create a transaction for signing a PSBT input and return its hash.
  *
- * :param psbt: The PSBT containing the input to compute a signing hash for.
+ * :param psbt: The PSBT containing the input to compute a signature hash for.
  * :param index: The zero-based index of the PSBT input to sign.
  * :param tx: The transaction to generate the signature hash from.
  * :param script: The (unprefixed) scriptCode for the input being signed.
  * :param script_len: Length of ``script`` in bytes.
+ * :param flags: Flags controlling signature hash generation. Must be 0.
  * :param bytes_out: Destination for the signature hash.
  * FIXED_SIZED_OUTPUT(len, bytes_out, SHA256_LEN)
  */
@@ -2131,6 +2132,7 @@ WALLY_CORE_API int wally_psbt_get_input_signature_hash(
     const struct wally_tx *tx,
     const unsigned char *script,
     size_t script_len,
+    uint32_t flags,
     unsigned char *bytes_out,
     size_t len);
 

src/psbt.c

@@ -4009,15 +4009,16 @@ int wally_psbt_get_input_scriptcode(const struct wally_psbt *psbt, size_t index,
 int wally_psbt_get_input_signature_hash(struct wally_psbt *psbt, size_t index,
                                         const struct wally_tx *tx,
                                         const unsigned char *script, size_t script_len,
+                                        uint32_t flags,
                                         unsigned char *bytes_out, size_t len)
 {
     const struct wally_psbt_input *inp = psbt_get_input(psbt, index);
     uint64_t satoshi;
-    uint32_t sighash, flags;
+    uint32_t sighash, sig_flags;
     size_t is_pset;
     int ret;
 
-    if (!inp || !tx)
+    if (!inp || !tx || flags)
         return WALLY_EINVAL;
 
     if ((ret = wally_psbt_is_elements(psbt, &is_pset)) != WALLY_OK)
@@ -4026,7 +4027,7 @@ int wally_psbt_get_input_signature_hash(struct wally_psbt *psbt, size_t index,
     sighash = inp->sighash ? inp->sighash : WALLY_SIGHASH_ALL;
     if (sighash & 0xffffff00)
         return WALLY_EINVAL;
-    flags = inp->witness_utxo ? WALLY_TX_FLAG_USE_WITNESS : 0;
+    sig_flags = inp->witness_utxo ? WALLY_TX_FLAG_USE_WITNESS : 0;
 
     if (is_pset) {
         if (!inp->witness_utxo)
@@ -4036,14 +4037,15 @@ int wally_psbt_get_input_signature_hash(struct wally_psbt *psbt, size_t index,
                                                     script, script_len,
                                                     inp->witness_utxo->value,
                                                     inp->witness_utxo->value_len,
-                                                    sighash, flags, bytes_out, len);
+                                                    sighash, sig_flags, bytes_out,
+                                                    len);
 #else
         return WALLY_EINVAL; /* Unsupported */
 #endif /* BUILD_ELEMENTS */
     }
     satoshi = inp->witness_utxo ? inp->witness_utxo->satoshi : 0;
     return wally_tx_get_btc_signature_hash(tx, index, script, script_len,
-                                           satoshi, sighash, flags,
+                                           satoshi, sighash, sig_flags,
                                            bytes_out, len);
 }
 
@@ -4139,7 +4141,7 @@ int wally_psbt_sign_bip32(struct wally_psbt *psbt,
         if (ret == WALLY_OK)
             ret = wally_psbt_get_input_signature_hash(psbt, i, tx,
                                                       scriptcode, scriptcode_len,
-                                                      txhash, sizeof(txhash));
+                                                      0, txhash, sizeof(txhash));
         /* Sign the input */
         if (ret == WALLY_OK)
             ret = wally_psbt_sign_input_bip32(psbt, i, subindex,

src/test/util.py

@@ -398,7 +398,7 @@ class wally_psbt(Structure):
     ('wally_psbt_get_input_bip32_key_from_alloc', c_int, [POINTER(wally_psbt), c_size_t, c_size_t, c_uint32, POINTER(ext_key), POINTER(POINTER(ext_key))]),
     ('wally_psbt_get_input_scriptcode', c_int, [POINTER(wally_psbt), c_size_t, c_void_p, c_size_t, c_void_p, c_size_t, c_size_t_p]),
     ('wally_psbt_get_input_scriptcode_len', c_int, [POINTER(wally_psbt), c_size_t, c_void_p, c_size_t, c_size_t_p]),
-    ('wally_psbt_get_input_signature_hash', c_int, [POINTER(wally_psbt), c_size_t, POINTER(wally_tx), c_void_p, c_size_t, c_void_p, c_size_t]),
+    ('wally_psbt_get_input_signature_hash', c_int, [POINTER(wally_psbt), c_size_t, POINTER(wally_tx), c_void_p, c_size_t, c_uint32, c_void_p, c_size_t]),
     ('wally_psbt_get_input_signing_script', c_int, [POINTER(wally_psbt), c_size_t, c_void_p, c_size_t, c_size_t_p]),
     ('wally_psbt_get_input_signing_script_len', c_int, [POINTER(wally_psbt), c_size_t, c_size_t_p]),
     ('wally_psbt_get_length', c_int, [POINTER(wally_psbt), c_uint32, c_size_t_p]),

src/wasm_package/functions.js

@@ -276,7 +276,7 @@ export function psbt_get_input_required_locktime(psbt: Ref_wally_psbt, index: nu
 export function psbt_get_input_scriptcode_len(psbt: Ref_wally_psbt, index: number, script: Buffer|Uint8Array): number;
 export function psbt_get_input_sequence(psbt: Ref_wally_psbt, index: number): number;
 export function psbt_get_input_sighash(psbt: Ref_wally_psbt, index: number): number;
-export function psbt_get_input_signature_hash(psbt: Ref_wally_psbt, index: number, tx: Ref_wally_tx, script: Buffer|Uint8Array): Buffer;
+export function psbt_get_input_signature_hash(psbt: Ref_wally_psbt, index: number, tx: Ref_wally_tx, script: Buffer|Uint8Array, flags: number): Buffer;
 export function psbt_get_input_signature_len(psbt: Ref_wally_psbt, index: number, subindex: number): number;
 export function psbt_get_input_signatures_size(psbt: Ref_wally_psbt, index: number): number;
 export function psbt_get_input_signing_script_len(psbt: Ref_wally_psbt, index: number): number;