bitcoin-util evalscript subcommand

[ajtowns]

Introduces an evalscript subcommand for bitcoin-util that evaluates a script directly.

Relies on upstream PRs bitcoin#28802 and bitcoin#28806.

Example:

$ ./bitcoin-util evalscript '515293'
{
  "script": {
    "asm": "1 2 OP_ADD",
    "hex": "515293",
    "type": "nonstandard"
  },
  "sigversion": "witness_v0",
  "script_flags":  [
    "CHECKLOCKTIMEVERIFY",
    "CHECKSEQUENCEVERIFY",
    "DERSIG",
    "NULLDUMMY",
    "P2SH",
    "TAPROOT,WITNESS"
  ],
  "stack-after": [
    "03"
  ],
  "sigop-count": 0,
  "success": true
}

Provides --sigversion (base, witness_v0 or tapscript) to select different script versions, and --script_flags to enable the various script flags, eg:

$ ./bitcoin-util --sigversion=tapscript --script_flags=OP_CAT evalscript '51527e'
{
  "script": {
    "asm": "1 2 OP_CAT",
    "hex": "51527e",
    "type": "nonstandard"
  },
  "sigversion": "tapscript",
  "script_flags": [
    "OP_CAT"
  ],
  "stack-after": [
    "0102"
  ],
  "sigop-count": 0,
  "success": true
}

[ajtowns]

I think the signature checking is usable now:

$ ./bitcoin-util --sigversion=tapscript \
  --tx=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 \
  --input=0 \
  --spent_output=204e000000000000225120bc2d293f6482e242e12330379bb255f9f2f853a25ec19ed40f54a149c3af6315 \
  --ipk=50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0 \
  --script_flags=STANDARD \
  evalscript \
  '0x201bd43c4c240e0244871afe0650bdbedb13780a9d0644c4aa2398f46f20f46130 OP_CHECKSIGVERIFY 2016 OP_CHECKSEQUENCEVERIFY' \
  'ec3517b63e035c22f3659bfd30b9f440049b697a8d1cb8ef721658d683fa66c6c3f598d25682381c43fba7c94b5f994537041960d0c0e8c596fdcc1170b241c8'  

{
  "script": {
    "asm": "1bd43c4c240e0244871afe0650bdbedb13780a9d0644c4aa2398f46f20f46130 OP_CHECKSIGVERIFY 2016 OP_CHECKSEQUENCEVERIFY",
    "hex": "201bd43c4c240e0244871afe0650bdbedb13780a9d0644c4aa2398f46f20f46130ad02e007b2",
    "type": "nonstandard"
  },
  "sigversion": "tapscript",
  "script_flags": [
    "ANYPREVOUT",
    "CHECKLOCKTIMEVERIFY",
    "CHECKSEQUENCEVERIFY",
    "CLEANSTACK",
    "CONST_SCRIPTCODE",
    "DEFAULT_CHECK_TEMPLATE_VERIFY_HASH",
    "DERSIG",
    "DISCOURAGE_OP_SUCCESS",
    "DISCOURAGE_UPGRADABLE_CHECK_TEMPLATE_VERIFY_HASH",
    "DISCOURAGE_UPGRADABLE_NOPS",
    "DISCOURAGE_UPGRADABLE_PUBKEYTYPE",
    "DISCOURAGE_UPGRADABLE_TAPROOT_VERSION",
    "DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM",
    "LOW_S",
    "MINIMALDATA",
    "MINIMALIF",
    "NULLDUMMY",
    "NULLFAIL",
    "OP_CAT",
    "P2SH",
    "STRICTENC",
    "TAPROOT",
    "WITNESS",
    "WITNESS_PUBKEYTYPE"
  ],
  "stack-after": [
    "e007"
  ],
  "sigop-count": 0,
  "success": true
}

(Taken from tx 928f9e4c445d2f67d44a29600bf48616aa16797e9d0b8a9ef81532358a6211e7 on signet)

[ajtowns]

CHECKSIG doesn't work if you don't specify the various options, and CSV/CLTV don't work unless you specify a tx that actually satisfies the constraints. Might be good to grab the DummySignatureChecker from script/sign.cpp and use that when the --tx etc args aren't specified.

EDIT: now done