Merge bitcoin#15770: rpc: Validate maxfeerate with AmountFromValue

aa410c2 rpc: Validate maxfeerate with AmountFromValue (João Barbosa)

Pull request description:

  With this change `maxfeerate` can also be set as a string, accordingly to the help test:
  ```
    maxfeerate    (numeric or string,
  ```
  Beside, there are no tests for the removed errors.

ACKs for commit aa410c:
  meshcollider:
    utACK bitcoin@aa410c2
  MarcoFalke:
    utACK aa410c2 Good catch

Tree-SHA512: f3bfea91dc7daa943729e270585dbf333055aeda805fbd01eaab20a7e0e6147382647c11525334382d198df0d3d45da6102b541efda5a1361f96271c98d5d89d

Author: MarcoFalke

src/rpc/rawtransaction.cpp

@@ -818,15 +818,13 @@ static UniValue sendrawtransaction(const JSONRPCRequest& request)
     // TODO: temporary migration code for old clients. Remove in v0.20
     if (request.params[1].isBool()) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Second argument must be numeric (maxfeerate) and no longer supports a boolean. To allow a transaction with high fees, set maxfeerate to 0.");
-    } else if (request.params[1].isNum()) {
+    } else if (!request.params[1].isNull()) {
         size_t weight = GetTransactionWeight(*tx);
         CFeeRate fr(AmountFromValue(request.params[1]));
         // the +3/4 part rounds the value up, and is the same formula used when
         // calculating the fee for a transaction
         // (see GetVirtualTransactionSize)
         max_raw_tx_fee = fr.GetFee((weight+3)/4);
-    } else if (!request.params[1].isNull()) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, "second argument (maxfeerate) must be numeric");
     }
 
     uint256 txid;
@@ -900,15 +898,13 @@ static UniValue testmempoolaccept(const JSONRPCRequest& request)
     // TODO: temporary migration code for old clients. Remove in v0.20
     if (request.params[1].isBool()) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Second argument must be numeric (maxfeerate) and no longer supports a boolean. To allow a transaction with high fees, set maxfeerate to 0.");
-    } else if (request.params[1].isNum()) {
+    } else if (!request.params[1].isNull()) {
         size_t weight = GetTransactionWeight(*tx);
         CFeeRate fr(AmountFromValue(request.params[1]));
         // the +3/4 part rounds the value up, and is the same formula used when
         // calculating the fee for a transaction
         // (see GetVirtualTransactionSize)
         max_raw_tx_fee = fr.GetFee((weight+3)/4);
-    } else if (!request.params[1].isNull()) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, "second argument (maxfeerate) must be numeric");
     }
 
     UniValue result(UniValue::VARR);

test/functional/rpc_rawtransaction.py

@@ -446,9 +446,9 @@ def run_test(self):
         # and sendrawtransaction should throw
         assert_raises_rpc_error(-26, "absurdly-high-fee", self.nodes[2].sendrawtransaction, rawTxSigned['hex'], 0.00001000)
         # And below calls should both succeed
-        testres = self.nodes[2].testmempoolaccept(rawtxs=[rawTxSigned['hex']], maxfeerate=0.00007000)[0]
+        testres = self.nodes[2].testmempoolaccept(rawtxs=[rawTxSigned['hex']], maxfeerate='0.00007000')[0]
         assert_equal(testres['allowed'], True)
-        self.nodes[2].sendrawtransaction(hexstring=rawTxSigned['hex'], maxfeerate=0.00007000)
+        self.nodes[2].sendrawtransaction(hexstring=rawTxSigned['hex'], maxfeerate='0.00007000')
 
 
 if __name__ == '__main__':