Merge bitcoin/bitcoin#32821: rpc: Handle -named argument parsing where '=' character is used

f53dbbc505 test: Add functional tests for named argument parsing (zaidmstrr)
694f04e2bd rpc: Handle -named argument parsing where '=' character is used (zaidmstrr)

Pull request description:

  Addresses [comment](https://github.com/bitcoin/bitcoin/pull/31375#discussion_r2091886628) and [this](https://github.com/bitcoin/bitcoin/pull/31375#discussion_r2092039999).

  The [PR #31375](https://github.com/bitcoin/bitcoin/pull/31375) got merged and enables `-named` by default in the `bitcoin rpc` interface; `bitcoin rpc` corresponds to `bitcoin-cli -named` as it's just a wrapper.  Now, the problem arises when we try to parse the positional paramater which might contain "=" character.  This splits the parameter into two parts first, before the "=" character, which treats this as the parameter name, but the other half is mostly passed as an empty string. Here, the first part of the string is an unknown parameter name; thus, an error is thrown. These types of errors are only applicable to those RPCs which might contain the `=` character as a parameter. Some examples are `finalizepsbt`, `decodepsbt`, `verifymessage` etc.

  This is the one example of the error in `finalizepsbt` RPC:
  ```
  ./bitcoin-cli -named -regtest finalizepsbt cHNidP8BAJoCAAAAAqvNEjSrzRI0q80SNKvNEjSrzRI0q80SNKvNEjSrzRI0AAAAAAD9////NBLNqzQSzas0Es2rNBLNqzQSzas0Es2rNBLNqzQSzasBAAAAAP3///8CoIYBAAAAAAAWABQVQBGVs/sqFAmC8HZ8O+g1htqivkANAwAAAAAAFgAUir7MzgyzDnRMjdkVa7d+Dwr07jsAAAAAAAAAAAA=
  error code: -8
  error message:
  Unknown named parameter cHNidP8BAJoCAAAAAqvNEjSrzRI0q80SNKvNEjSrzRI0q80SNKvNEjSrzRI0AAAAAAD9////NBLNqzQSzas0Es2rNBLNqzQSzas0Es2rNBLNqzQSzasBAAAAAP3///8CoIYBAAAAAAAWABQVQBGVs/sqFAmC8HZ8O+g1htqivkANAwAAAAAAFgAUir7MzgyzDnRMjdkVa7d+Dwr07jsAAAAAAAAAAAA
  ```
  This PR fixes this by updating the `vRPCConvertParams` table that identifies parameters that need special handling in `-named` parameter mode. The parser now recognises these parameters and handles strings with "=" char correctly, preventing them from being incorrectly split as parameter assignments.

ACKs for top commit:
  ryanofsky:
    Code review ACK f53dbbc505. Just applied comment & test suggestions since last review
  kannapoix:
    Code review ACK: f53dbbc505
  achow101:
    ACK f53dbbc505

Tree-SHA512: 1b517144efeff45a4c4256c27a39ddf187f1d6189d133402a45171678214a10ff2925c31edcfd556d67f85bd26d42f63c528b941b68c9880eab443f2c883e681

test/functional/rpc_psbt.py

@@ -369,6 +369,43 @@ class PSBTTest(BitcoinTestFramework):
         changepos = psbtx["changepos"]
         assert_equal(decoded_psbt["tx"]["vout"][changepos]["scriptPubKey"]["type"], expected_type)
 
+    def test_psbt_named_parameter_handling(self):
+        """Test that PSBT Base64 parameters with '=' padding are handled correctly in -named mode"""
+        self.log.info("Testing PSBT Base64 parameter handling with '=' padding characters")
+        node = self.nodes[0]
+        psbt_with_padding = "cHNidP8BAJoCAAAAAqvNEjSrzRI0q80SNKvNEjSrzRI0q80SNKvNEjSrzRI0AAAAAAD9////NBLNqzQSzas0Es2rNBLNqzQSzas0Es2rNBLNqzQSzasBAAAAAP3///8CoIYBAAAAAAAWABQVQBGVs/sqFAmC8HZ8O+g1htqivkANAwAAAAAAFgAUir7MzgyzDnRMjdkVa7d+Dwr07jsAAAAAAAAAAAA="
+
+        # Test decodepsbt with explicit named parameter containing '=' padding
+        result = node.cli("-named", "decodepsbt", f"psbt={psbt_with_padding}").send_cli()
+        assert 'tx' in result
+
+        # Test decodepsbt with positional argument containing '=' padding
+        result = node.cli("-named", "decodepsbt", psbt_with_padding).send_cli()
+        assert 'tx' in result
+
+        # Test analyzepsbt with positional argument containing '=' padding
+        result = node.cli("-named", "analyzepsbt", psbt_with_padding).send_cli()
+        assert 'inputs' in result
+
+        # Test finalizepsbt with positional argument containing '=' padding
+        result = node.cli("-named", "finalizepsbt", psbt_with_padding, "extract=true").send_cli()
+        assert 'complete' in result
+
+        # Test walletprocesspsbt with positional argument containing '=' padding
+        result = node.cli("-named", "walletprocesspsbt", psbt_with_padding).send_cli()
+        assert 'complete' in result
+
+        # Test utxoupdatepsbt with positional argument containing '=' padding
+        result = node.cli("-named", "utxoupdatepsbt", psbt_with_padding).send_cli()
+        assert isinstance(result, str) and len(result) > 0
+
+        # Test that unknown parameter with '=' gets treated as positional and return error
+        unknown_psbt_param = "unknown_param_data=more_data="
+        # This should be treated as positional and fail with decode error, not parameter error
+        assert_raises_rpc_error(-22, "TX decode failed invalid base64", node.cli("-named", "finalizepsbt", unknown_psbt_param).send_cli)
+
+        self.log.info("PSBT parameter handling test completed successfully")
+
     def run_test(self):
         # Create and fund a raw tx for sending 10 BTC
         psbtx1 = self.nodes[0].walletcreatefundedpsbt([], {self.nodes[2].getnewaddress():10})['psbt']
@@ -1211,6 +1248,7 @@ class PSBTTest(BitcoinTestFramework):
         if not self.options.usecli:
             self.test_sighash_mismatch()
         self.test_sighash_adding()
+        self.test_psbt_named_parameter_handling()
 
 if __name__ == '__main__':
     PSBTTest(__file__).main()