fix: 0 ARKtoshi amount handling (#85)

Author: sleepdefic1t

CHANGELOG.md

@@ -15,6 +15,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Changed
 
+### Changed
+
+- properly handle 0 ARKtoshi Transaction amounts.
 - improved Windows support ([#83])
 
 ## [0.3.1] - 2019-02-19

src/include/cpp-crypto/transactions/builder.h

@@ -18,8 +18,17 @@ namespace Transactions {
 
 class Builder {
  public:
+  /**
+  * Builder::buildTransfer()
+  *
+  * note: The 'Type 0'/Transfer amount must be greater than 0 ARKtoshi.
+  * If amount is not > 0, Builder will return an empty Transaction object and
+  * validation will fail.
+  **/
   static Transaction buildTransfer(std::string recipientId, uint64_t amount, std::string vendorField,
                                    std::string passphrase, std::string secondPassphrase = "");
+  /**/
+
   static Transaction buildSecondSignatureRegistration(std::string passphrase, std::string secondPassphrase = "");
   static Transaction buildDelegateRegistration(std::string username, std::string passphrase,
                                                std::string secondPassphrase = "");

src/transactions/builder.cpp

@@ -13,6 +13,8 @@ namespace Transactions {
 Transaction Builder::buildTransfer(std::string recipientId, uint64_t amount, std::string vendorField,
                                    std::string passphrase, std::string secondPassphrase) {
   Transaction transaction;
+  if (amount < 1ull) { return transaction; };
+
   transaction.type = Enums::Types::TRANSFER;
   transaction.fee = Configuration::Fee().get(Enums::Types::TRANSFER);
   transaction.recipientId = std::move(recipientId);

src/transactions/transaction.cpp

@@ -58,6 +58,8 @@ bool Ark::Crypto::Transactions::Transaction::internalVerify(
     std::string publicKey,
     std::vector<uint8_t> bytes,
     std::string signature) const {
+  if (bytes.empty()) { return false; };
+
   const auto hash = Sha256::getHash(&bytes[0], bytes.size());
   const auto key = Identities::PublicKey::fromHex(publicKey.c_str());
   auto signatureBytes = HexToBytes(signature.c_str());
@@ -69,6 +71,8 @@ std::vector<uint8_t> Ark::Crypto::Transactions::Transaction::toBytes(
     bool skipSecondSignature) const {
   std::vector<uint8_t> bytes;
 
+  if (this->type == 0 && amount < 1ull) { return bytes; };
+
   pack(bytes, this->type);
   pack(bytes, this->timestamp);
 

test/transactions/builder.cpp

@@ -13,4 +13,14 @@ TEST(transactions, build_transfer) {
   ASSERT_STREQ("D61mfSggzbvQgTUe6JhYKH2doHaqJ3Dyib", actual.recipientId.c_str());
   ASSERT_TRUE(100000000 == actual.amount);
   ASSERT_STREQ("", actual.vendorField.c_str());
+
+  // test 0 ARKtoshi value
+  const auto shouldBeEmpty = Ark::Crypto::Transactions::Builder::buildTransfer(
+      "D61mfSggzbvQgTUe6JhYKH2doHaqJ3Dyib",
+      0,
+      "",
+      "Secret passphrase");
+  ASSERT_STREQ("", shouldBeEmpty.recipientId.c_str());
+  ASSERT_EQ(0, shouldBeEmpty.amount);
+  ASSERT_FALSE(shouldBeEmpty.verify());
 }