Merge #19215: psbt: Include and allow both non_witness_utxo and witness_utxo for segwit inputs

84d295e51341a126a6c3cbeea7a8caa04c7b5bc3 tests: Check that segwit inputs in psbt have both UTXO types (Andrew Chow)
46004790588c24174a0bec49b540d158ce163ffd psbt: always put a non_witness_utxo and don't remove it (Andrew Chow)
5279d8bc07d601fe6a67ad665fbc7591fe73c7de psbt: Allow both non_witness_utxo and witness_utxo (Andrew Chow)
72f6bec1da198764d4648a10a61c485e7ab65e9e rpc: show both UTXOs in decodepsbt (Andrew Chow)

Pull request description:

  Due to recent changes to hardware wallets, the full previous transaction will need to be provided for segwit inputs. Since some software may be checking for the existence of a `witness_utxo` to determine whether to produce a segwit signature, we keep that field to ease the transition.

  Because all of the sanity checks implemented by the `IsSane` functions were related to having mixed segwit and non-segwit data in a PSBT, those functions are removed as those checks are no longer proper.

  Some tests are updated/removed to accommodate this and a simple test added to check that both UTXOs are being added to segwit inputs.

  As discussed in the wallet IRC meeting, our own signer will not require `non_witness_utxo` for segwit inputs.

ACKs for top commit:
  Sjors:
    utACK 84d295e51341a126a6c3cbeea7a8caa04c7b5bc3 (didn't retest compared to 836d6fc, but fortunately HWI's CI tracks our master branch, with a bunch of hardware wallet simulators)
  ryanofsky:
    Code review re-ACK 84d295e51341a126a6c3cbeea7a8caa04c7b5bc3. No changes since last review, but now I understand the context better. I think it would good to improve the comments as suggested https://github.com/bitcoin/bitcoin/pull/19215#discussion_r447889473 and maybe refer to
  meshcollider:
    utACK 84d295e51341a126a6c3cbeea7a8caa04c7b5bc3

Tree-SHA512: ccc1fd3c16ac3859f5aca4fa489bd40f68be0b81bbdc4dd51188bbf28827a8642dc8b605a37318e5f16cf40f1c4910052dace2f27eca21bb58435f02a443e940

1 files changed, 0 insertions, 2 deletions

diff --git a/src/test/fuzz/psbt.cpp b/src/test/fuzz/psbt.cpp
index 64328fb66e..908e2b16f2 100644
--- a/src/test/fuzz/psbt.cpp
+++ b/src/test/fuzz/psbt.cpp
@@ -39,7 +39,6 @@ void test_one_input(const std::vector<uint8_t>& buffer)
     }
 
     (void)psbt.IsNull();
-    (void)psbt.IsSane();
 
     Optional<CMutableTransaction> tx = psbt.tx;
     if (tx) {
@@ -50,7 +49,6 @@ void test_one_input(const std::vector<uint8_t>& buffer)
     for (const PSBTInput& input : psbt.inputs) {
         (void)PSBTInputSigned(input);
         (void)input.IsNull();
-        (void)input.IsSane();
     }
 
     for (const PSBTOutput& output : psbt.outputs) {