rpc: bugfix: Properly use iswitness in converttopsbt

Also explain the param in all RPCs

Author: MarcoFalke

src/rpc/rawtransaction.cpp

@@ -435,8 +435,13 @@ static UniValue decoderawtransaction(const JSONRPCRequest& request)
                 "\nReturn a JSON object representing the serialized, hex-encoded transaction.\n",
                 {
                     {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The transaction hex string"},
-                    {"iswitness", RPCArg::Type::BOOL, /* default */ "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction\n"
-            "                         If iswitness is not present, heuristic tests will be used in decoding"},
+                    {"iswitness", RPCArg::Type::BOOL, /* default */ "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction.\n"
+                        "If iswitness is not present, heuristic tests will be used in decoding.\n"
+                        "If true, only witness deserialization will be tried.\n"
+                        "If false, only non-witness deserialization will be tried.\n"
+                        "This boolean should reflect whether the transaction has inputs\n"
+                        "(e.g. fully valid, or on-chain transactions), if known by the caller."
+                    },
                 },
                 RPCResult{
             "{\n"
@@ -1422,12 +1427,15 @@ UniValue converttopsbt(const JSONRPCRequest& request)
                 "createpsbt and walletcreatefundedpsbt should be used for new applications.\n",
                 {
                     {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex string of a raw transaction"},
-                    {"permitsigdata", RPCArg::Type::BOOL, /* default */ "false", "If true, any signatures in the input will be discarded and conversion.\n"
+                    {"permitsigdata", RPCArg::Type::BOOL, /* default */ "false", "If true, any signatures in the input will be discarded and conversion\n"
                             "                              will continue. If false, RPC will fail if any signatures are present."},
                     {"iswitness", RPCArg::Type::BOOL, /* default */ "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction.\n"
-                            "                              If iswitness is not present, heuristic tests will be used in decoding. If true, only witness deserializaion\n"
-                            "                              will be tried. If false, only non-witness deserialization will be tried. Only has an effect if\n"
-                            "                              permitsigdata is true."},
+                        "If iswitness is not present, heuristic tests will be used in decoding.\n"
+                        "If true, only witness deserialization will be tried.\n"
+                        "If false, only non-witness deserialization will be tried.\n"
+                        "This boolean should reflect whether the transaction has inputs\n"
+                        "(e.g. fully valid, or on-chain transactions), if known by the caller."
+                    },
                 },
                 RPCResult{
                             "  \"psbt\"        (string)  The resulting raw transaction (base64-encoded string)\n"
@@ -1444,16 +1452,15 @@ UniValue converttopsbt(const JSONRPCRequest& request)
         throw std::runtime_error(help.ToString());
     }
 
-
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL, UniValue::VBOOL}, true);
 
     // parse hex string from parameter
     CMutableTransaction tx;
     bool permitsigdata = request.params[1].isNull() ? false : request.params[1].get_bool();
     bool witness_specified = !request.params[2].isNull();
     bool iswitness = witness_specified ? request.params[2].get_bool() : false;
-    bool try_witness = permitsigdata ? (witness_specified ? iswitness : true) : false;
-    bool try_no_witness = permitsigdata ? (witness_specified ? !iswitness : true) : true;
+    const bool try_witness = witness_specified ? iswitness : true;
+    const bool try_no_witness = witness_specified ? !iswitness : true;
     if (!DecodeHexTx(tx, request.params[0].get_str(), try_no_witness, try_witness)) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     }

src/wallet/rpcwallet.cpp

@@ -3030,8 +3030,13 @@ static UniValue fundrawtransaction(const JSONRPCRequest& request)
                             "         \"CONSERVATIVE\""},
                         },
                         "options"},
-                    {"iswitness", RPCArg::Type::BOOL, /* default */ "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction \n"
-                            "                              If iswitness is not present, heuristic tests will be used in decoding"},
+                    {"iswitness", RPCArg::Type::BOOL, /* default */ "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction.\n"
+                        "If iswitness is not present, heuristic tests will be used in decoding.\n"
+                        "If true, only witness deserialization will be tried.\n"
+                        "If false, only non-witness deserialization will be tried.\n"
+                        "This boolean should reflect whether the transaction has inputs\n"
+                        "(e.g. fully valid, or on-chain transactions), if known by the caller."
+                    },
                 },
                 RPCResult{
                             "{\n"

test/functional/rpc_psbt.py

@@ -152,9 +152,10 @@ def run_test(self):
 
         # Make sure that a non-psbt with signatures cannot be converted
         # Error could be either "TX decode failed" (segwit inputs causes parsing to fail) or "Inputs must not have scriptSigs and scriptWitnesses"
+        # We must set iswitness=True because the serialized transaction has inputs and is therefore a witness transaction
         signedtx = self.nodes[0].signrawtransactionwithwallet(rawtx['hex'])
-        assert_raises_rpc_error(-22, "", self.nodes[0].converttopsbt, signedtx['hex'])
-        assert_raises_rpc_error(-22, "", self.nodes[0].converttopsbt, signedtx['hex'], False)
+        assert_raises_rpc_error(-22, "", self.nodes[0].converttopsbt, hexstring=signedtx['hex'], iswitness=True)
+        assert_raises_rpc_error(-22, "", self.nodes[0].converttopsbt, hexstring=signedtx['hex'], permitsigdata=False, iswitness=True)
         # Unless we allow it to convert and strip signatures
         self.nodes[0].converttopsbt(signedtx['hex'], True)