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helpers.go
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helpers.go
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package txnbuild
import (
"fmt"
"github.com/stellar/go/amount"
"github.com/stellar/go/strkey"
"github.com/stellar/go/support/errors"
"github.com/stellar/go/xdr"
)
// validateStellarPublicKey returns an error if a public key is invalid. Otherwise, it returns nil.
// It is a wrapper around the IsValidEd25519PublicKey method of the strkey package.
func validateStellarPublicKey(publicKey string) error {
if publicKey == "" {
return errors.New("public key is undefined")
}
if !strkey.IsValidEd25519PublicKey(publicKey) {
return errors.Errorf("%s is not a valid stellar public key", publicKey)
}
return nil
}
// validateStellarSignerKey returns an error if a signerkey is invalid. Otherwise, it returns nil.
func validateStellarSignerKey(signerKey string) error {
if signerKey == "" {
return errors.New("signer key is undefined")
}
var xdrKey xdr.SignerKey
if err := xdrKey.SetAddress(signerKey); err != nil {
return errors.Errorf("%s is not a valid stellar signer key", signerKey)
}
return nil
}
// validateStellarAsset checks if the asset supplied is a valid stellar Asset. It returns an error if the asset is
// nil, has an invalid asset code or issuer.
func validateStellarAsset(asset Asset) error {
if asset == nil {
return errors.New("asset is undefined")
}
if asset.IsNative() {
return nil
}
_, err := asset.GetType()
if err != nil {
return err
}
err = validateStellarPublicKey(asset.GetIssuer())
if err != nil {
return errors.Errorf("asset issuer: %s", err.Error())
}
return nil
}
// validateAmount checks if the provided value is a valid stellar amount, it returns an error if not.
// This is used to validate price and amount fields in structs.
func validateAmount(n interface{}) error {
var stellarAmount int64
// type switch can be extended to handle other types. Currently, the types for number values in the txnbuild
// package are string or int64.
switch value := n.(type) {
case int64:
stellarAmount = value
case string:
v, err := amount.ParseInt64(value)
if err != nil {
return err
}
stellarAmount = v
default:
return errors.Errorf("could not parse expected numeric value %v", n)
}
if stellarAmount < 0 {
return errors.New("amount can not be negative")
}
return nil
}
// validateAssetCode checks if the provided asset is valid as an asset code.
// It returns an error if the asset is invalid.
// The asset must be non native (XLM) with a valid asset code.
func validateAssetCode(asset Asset) error {
// Note: we are not using validateStellarAsset() function for AllowTrust operations because it requires the
// following :
// - asset is non-native
// - asset code is valid
// - asset issuer is not required. This is actually ignored by the operation
if asset == nil {
return errors.New("asset is undefined")
}
if asset.IsNative() {
return errors.New("native (XLM) asset type is not allowed")
}
_, err := asset.GetType()
if err != nil {
return err
}
return nil
}
// validateChangeTrustAsset checks if the provided asset is valid for use in ChangeTrust operation.
// It returns an error if the asset is invalid.
// The asset must be non native (XLM) with a valid asset code and issuer.
func validateChangeTrustAsset(asset Asset) error {
// Note: we are not using validateStellarAsset() function for ChangeTrust operations because it requires the
// following :
// - asset is non-native
// - asset code is valid
// - asset issuer is valid
err := validateAssetCode(asset)
if err != nil {
return err
}
err = validateStellarPublicKey(asset.GetIssuer())
if err != nil {
return errors.Errorf("asset issuer: %s", err.Error())
}
return nil
}
// validatePassiveOffer checks if the fields of a CreatePassiveOffer struct are valid.
// It checks that the buying and selling assets are valid stellar assets, and that amount and price are valid.
// It returns an error if any field is invalid.
func validatePassiveOffer(buying, selling Asset, offerAmount, price string) error {
// Note: see discussion on how this can be improved:
// https://github.com/stellar/go/pull/1707#discussion_r321508440
err := validateStellarAsset(buying)
if err != nil {
return NewValidationError("Buying", err.Error())
}
err = validateStellarAsset(selling)
if err != nil {
return NewValidationError("Selling", err.Error())
}
err = validateAmount(offerAmount)
if err != nil {
return NewValidationError("Amount", err.Error())
}
err = validateAmount(price)
if err != nil {
return NewValidationError("Price", err.Error())
}
return nil
}
// validateOffer checks if the fields of ManageBuyOffer or ManageSellOffer struct are valid.
// It checks that the buying and selling assets are valid stellar assets, and that amount, price and offerID
// are valid. It returns an error if any field is invalid.
func validateOffer(buying, selling Asset, offerAmount, price string, offerID int64) error {
err := validatePassiveOffer(buying, selling, offerAmount, price)
if err != nil {
return err
}
err = validateAmount(offerID)
if err != nil {
return NewValidationError("OfferID", err.Error())
}
return nil
}
// ValidationError is a custom error struct that holds validation errors of txnbuild's operation structs.
type ValidationError struct {
Field string // Field is the struct field on which the validation error occured.
Message string // Message is the validation error message.
}
// Error for ValidationError struct implements the error interface.
func (opError *ValidationError) Error() string {
return fmt.Sprintf("Field: %s, Error: %s", opError.Field, opError.Message)
}
// NewValidationError creates a ValidationError struct with the provided field and message values.
func NewValidationError(field, message string) *ValidationError {
return &ValidationError{
Field: field,
Message: message,
}
}
// ParseAssetString parses an asset string in canonical form (SEP-11) into an Asset structure.
// https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0011.md#asset
func ParseAssetString(canonical string) (Asset, error) {
assets, err := xdr.BuildAssets(canonical)
if err != nil {
return nil, errors.Wrap(err, "error parsing asset string")
}
if len(assets) != 1 {
return nil, errors.New("error parsing out a single asset")
}
// The above returned a list, so we'll need to grab the first element.
asset, err := assetFromXDR(assets[0])
if err != nil {
return nil, errors.Wrap(err, "error parsing asset string via XDR types")
}
return asset, nil
}