Fix off by small amounts in sent amount kaspa (#2220)

* Fix off by small amounts in sent amount kaspa

Floating point math causes inconsistencies when converting kas to sompi.

Use a method that parses the amount as a string, the converts it to
sompi then parse back to uint64

* Deal with SendAmount as strings all the way

* Consistent config handling

* Set variables directly from utils.KasToSompi

Use = instead of := to ensure no shadowing

* Fix validate amount regex

* Use decimal places as defined by constants

Also check if SompiPerKaspa is multiple of 10

* Minor updates for context clarity

cmd/kaspawallet/config.go

@@ -57,7 +57,7 @@ type sendConfig struct {
 	DaemonAddress            string   `long:"daemonaddress" short:"d" description:"Wallet daemon server to connect to"`
 	ToAddress                string   `long:"to-address" short:"t" description:"The public address to send Kaspa to" required:"true"`
 	FromAddresses            []string `long:"from-address" short:"a" description:"Specific public address to send Kaspa from. Use multiple times to accept several addresses" required:"false"`
-	SendAmount               float64  `long:"send-amount" short:"v" description:"An amount to send in Kaspa (e.g. 1234.12345678)"`
+	SendAmount               string   `long:"send-amount" short:"v" description:"An amount to send in Kaspa (e.g. 1234.12345678)"`
 	IsSendAll                bool     `long:"send-all" description:"Send all the Kaspa in the wallet (mutually exclusive with --send-amount)"`
 	UseExistingChangeAddress bool     `long:"use-existing-change-address" short:"u" description:"Will use an existing change address (in case no change address was ever used, it will use a new one)"`
 	Verbose                  bool     `long:"show-serialized" short:"s" description:"Show a list of hex encoded sent transactions"`
@@ -74,7 +74,7 @@ type createUnsignedTransactionConfig struct {
 	DaemonAddress            string   `long:"daemonaddress" short:"d" description:"Wallet daemon server to connect to"`
 	ToAddress                string   `long:"to-address" short:"t" description:"The public address to send Kaspa to" required:"true"`
 	FromAddresses            []string `long:"from-address" short:"a" description:"Specific public address to send Kaspa from. Use multiple times to accept several addresses" required:"false"`
-	SendAmount               float64  `long:"send-amount" short:"v" description:"An amount to send in Kaspa (e.g. 1234.12345678)"`
+	SendAmount               string   `long:"send-amount" short:"v" description:"An amount to send in Kaspa (e.g. 1234.12345678)"`
 	IsSendAll                bool     `long:"send-all" description:"Send all the Kaspa in the wallet (mutually exclusive with --send-amount)"`
 	UseExistingChangeAddress bool     `long:"use-existing-change-address" short:"u" description:"Will use an existing change address (in case no change address was ever used, it will use a new one)"`
 	config.NetworkFlags
@@ -296,8 +296,8 @@ func parseCommandLine() (subCommand string, config interface{}) {
 }
 
 func validateCreateUnsignedTransactionConf(conf *createUnsignedTransactionConfig) error {
-	if (!conf.IsSendAll && conf.SendAmount == 0) ||
+	if (!conf.IsSendAll && conf.SendAmount == "") ||
-		(conf.IsSendAll && conf.SendAmount > 0) {
+		(conf.IsSendAll && conf.SendAmount != "") {
 
 		return errors.New("exactly one of '--send-amount' or '--all' must be specified")
 	}
@@ -305,8 +305,8 @@ func validateCreateUnsignedTransactionConf(conf *createUnsignedTransactionConfig
 }
 
 func validateSendConfig(conf *sendConfig) error {
-	if (!conf.IsSendAll && conf.SendAmount == 0) ||
+	if (!conf.IsSendAll && conf.SendAmount == "") ||
-		(conf.IsSendAll && conf.SendAmount > 0) {
+		(conf.IsSendAll && conf.SendAmount != "") {
 
 		return errors.New("exactly one of '--send-amount' or '--all' must be specified")
 	}

cmd/kaspawallet/create_unsigned_tx.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/kaspanet/kaspad/cmd/kaspawallet/daemon/client"
 	"github.com/kaspanet/kaspad/cmd/kaspawallet/daemon/pb"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
+	"github.com/kaspanet/kaspad/cmd/kaspawallet/utils"
 )
 
 func createUnsignedTransaction(conf *createUnsignedTransactionConfig) error {
@@ -20,7 +20,12 @@ func createUnsignedTransaction(conf *createUnsignedTransactionConfig) error {
 	ctx, cancel := context.WithTimeout(context.Background(), daemonTimeout)
 	defer cancel()
 
-	sendAmountSompi := uint64(conf.SendAmount * constants.SompiPerKaspa)
+	sendAmountSompi, err := utils.KasToSompi(conf.SendAmount)
+
+	if err != nil {
+		return err
+	}
+
 	response, err := daemonClient.CreateUnsignedTransactions(ctx, &pb.CreateUnsignedTransactionsRequest{
 		From:                     conf.FromAddresses,
 		Address:                  conf.ToAddress,

cmd/kaspawallet/send.go

@@ -10,7 +10,7 @@ import (
 	"github.com/kaspanet/kaspad/cmd/kaspawallet/daemon/pb"
 	"github.com/kaspanet/kaspad/cmd/kaspawallet/keys"
 	"github.com/kaspanet/kaspad/cmd/kaspawallet/libkaspawallet"
-	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
+	"github.com/kaspanet/kaspad/cmd/kaspawallet/utils"
 	"github.com/pkg/errors"
 )
 
@@ -35,7 +35,11 @@ func send(conf *sendConfig) error {
 
 	var sendAmountSompi uint64
 	if !conf.IsSendAll {
-		sendAmountSompi = uint64(conf.SendAmount * constants.SompiPerKaspa)
+		sendAmountSompi, err = utils.KasToSompi(conf.SendAmount)
+
+		if err != nil {
+			return err
+		}
 	}
 
 	createUnsignedTransactionsResponse, err :=

cmd/kaspawallet/utils/format_kas.go

@@ -2,8 +2,13 @@ package utils
 
 import (
 	"fmt"
+	"math"
+	"regexp"
+	"strconv"
+	"strings"
 
 	"github.com/kaspanet/kaspad/domain/consensus/utils/constants"
+	"github.com/pkg/errors"
 )
 
 // FormatKas takes the amount of sompis as uint64, and returns amount of KAS with 8  decimal places
@@ -14,3 +19,50 @@ func FormatKas(amount uint64) string {
 	}
 	return res
 }
+
+// KasToSompi takes in a string representation of the Kas value to convert to Sompi
+func KasToSompi(amount string) (uint64, error) {
+	err := validateKASAmountFormat(amount)
+
+	if err != nil {
+		return 0, err
+	}
+
+	// after validation, amount can only be either an int OR
+	// a float with an int component and decimal places
+	parts := strings.Split(amount, ".")
+	amountStr := ""
+
+	if constants.SompiPerKaspa%10 != 0 {
+		return 0, errors.Errorf("Unable to convert to sompi when SompiPerKaspa is not a multiple of 10")
+	}
+
+	decimalPlaces := int(math.Log10(constants.SompiPerKaspa))
+	decimalStr := ""
+
+	if len(parts) == 2 {
+		decimalStr = parts[1]
+	}
+
+	amountStr = fmt.Sprintf("%s%-*s", parts[0], decimalPlaces, decimalStr) // Padded with spaces at the end to fill for missing decimals: Sample "0.01234    "
+	amountStr = strings.ReplaceAll(amountStr, " ", "0")                    // Make the spaces be 0s. Sample "0.012340000"
+
+	convertedAmount, err := strconv.ParseUint(amountStr, 10, 64)
+
+	return convertedAmount, err
+}
+
+func validateKASAmountFormat(amount string) error {
+	// Check whether it's an integer, or a float with max 8 digits
+	match, err := regexp.MatchString("^([1-9]\\d{0,11}|0)(\\.\\d{0,8})?$", amount)
+
+	if !match {
+		return errors.Errorf("Invalid amount")
+	}
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

cmd/kaspawallet/utils/format_kas_test.go

@@ -0,0 +1,90 @@
+package utils
+
+import "testing"
+
+// Takes in a string representation of the Kas value to convert to Sompi
+func TestKasToSompi(t *testing.T) {
+	type testVector struct {
+		originalAmount  string
+		convertedAmount uint64
+	}
+
+	validCases := []testVector{
+		{originalAmount: "0", convertedAmount: 0},
+		{originalAmount: "1", convertedAmount: 100000000},
+		{originalAmount: "33184.1489732", convertedAmount: 3318414897320},
+		{originalAmount: "21.35808032", convertedAmount: 2135808032},
+		{originalAmount: "184467440737.09551615", convertedAmount: 18446744073709551615},
+	}
+
+	for _, currentTestVector := range validCases {
+		convertedAmount, err := KasToSompi(currentTestVector.originalAmount)
+
+		if err != nil {
+			t.Error(err)
+		} else if convertedAmount != currentTestVector.convertedAmount {
+			t.Errorf("Expected %s, to convert to %d. Got: %d", currentTestVector.originalAmount, currentTestVector.convertedAmount, convertedAmount)
+		}
+	}
+
+	invalidCases := []string{
+		"184467440737.09551616", // Bigger than max uint64
+		"-1",
+		"a",
+		"",
+	}
+
+	for _, currentTestVector := range invalidCases {
+		_, err := KasToSompi(currentTestVector)
+
+		if err == nil {
+			t.Errorf("Expected an error but succeeded validation for test case %s", currentTestVector)
+		}
+	}
+}
+
+func TestValidateAmountFormat(t *testing.T) {
+	validCases := []string{
+		"0",
+		"1",
+		"1.0",
+		"0.1",
+		"0.12345678",
+		"111111111111.11111111", // 12 digits to the left of decimal, 8 digits to the right
+		"184467440737.09551615", // Maximum input that can be represented in sompi later
+		"184467440737.09551616", // Cannot be represented in sompi, but we'll acccept for "correct format"
+		"999999999999.99999999", // Cannot be represented in sompi, but we'll acccept for "correct format"
+	}
+
+	for _, testCase := range validCases {
+		err := validateKASAmountFormat(testCase)
+
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	invalidCases := []string{
+		"",
+		"a",
+		"-1",
+		"0.123456789",           // 9 decimal digits
+		".1",                    // decimal but no integer component
+		"0a",                    // Extra character
+		"0000000000000",         // 13 zeros
+		"012",                   // Int padded with zero
+		"00.1",                  // Decimal padded with zeros
+		"111111111111111111111", // all digits
+		"111111111111A11111111", // non-period/non-digit where decimal would be
+		"000000000000.00000000", // all zeros
+		"kaspa",                 // all text
+	}
+
+	for _, testCase := range invalidCases {
+		err := validateKASAmountFormat(testCase)
+
+		if err == nil {
+			t.Errorf("Expected an error but succeeded validation for test case %s", testCase)
+		}
+	}
+}