[Qt] add verifySize() function to PaymentServer

[Diapolo]

• add static verifySize() function to PaymentServer and move the logging
  on error into the function
• the function checks if the size is allowed as per BIP70

[jonasschnelli]

I would also strongly recommend to add a Unit-Test for verifySize().
We should no longer add implementations without test-coverage.
And i assume this is easy to test with another payment request in the fixtures.

[Diapolo]

@jonasschnelli As verifySize() IS used in PaymentServer::readPaymentRequestFromFile() we already have test coverage :). IMHO it doesn't make sense to spam paymentrequestdata.h with 50001 Bytes of garbage just to re-test verifySize() again. What do you think?

[jonasschnelli]

@Diapolo IMO we should add the 50001 bytes test. You might use this forged payment request http://jonasschnelli.ch/r1422608371.bitcoinpaymentrequest

I also tried to test PaymentServer::readPaymentRequestFromFile with 50001 random bytes. But there is no distinction between parsing error and size error (returns only a bool).
Is there a change to test the QWarning within a QT unit test? Just a little string comparison?

[Diapolo]

@jonasschnelli I'm fine with directly using verifySize() instead of PaymentServer::readPaymentRequestFromFile() (which can then be private again ^^). But we don't need a real invalid playment request for this check IMHO. As the check is triggerd by just if > 50000 bytes rule it can be random garbage data.

What do you mean by Is there a change to test the QWarning within a QT unit test? Just a little string comparison??

[jonasschnelli]

Tested, reviewed, stepped ACK.

nit: misses unit test

[jonasschnelli]

@Diapolo: sounds even better. I would recommend to just pass 50001 bytes through PaymentServer::verifySize. I understand that the test looks very trivial know. But the idea of test are that they give guidelines when extending the implementation.

[Diapolo]

@jonasschnelli Updated, I hope this is fine now?

[jonasschnelli]

tested ACK

[Diapolo]

Anything left to do for me to get this and other related pulls merged ;)?

[Diapolo]

Ping

[Diapolo]

@laanwj Mind giving this the final ACK ;)?

[jonasschnelli]

ReACK

[Diapolo]

@laanwj ping

[laanwj]

Why are you removing this test?

[Diapolo]

To be able to make readPaymentRequestFromFile private again, which I changed once and wasn't happy with it :). The function could also fail, if the file failed to open, which isn't what this test is for anyway.

[laanwj]

If you want to be able to test a private methods you could use a friend class / function. E.g. inside the class do

friend class PaymentServerTester;

Then do the testing in a class PaymentServerTester.

[Diapolo]

@laanwj It's not necessary here, but thanks for that C++ lesson :).

[Diapolo]

@jonasschnelli Maybe you can help me understand what's preventing this pull from getting merged?

[Diapolo]

@laanwj @jonasschnelli Ping

[laanwj]

@Diapolo because you removed the test for, unrelated, PaymentServer::readPaymentRequestFromFile

[Diapolo]

@laanwj As I said, I just made PaymentServer::readPaymentRequestFromFile() public, because I hacked the former unit-test. That function isn't reliable as unit-test because it can also fail if the file could not be opened (returns false then), which isn't what the test assumes, as we want to verify the DoS protection.

[jgarzik]

ut ACK

[Diapolo]

@laanwj Fixed merge-conflict, ready now.

[Diapolo]

@laanwj Ping

[Diapolo]

Final ping!