How can I prohibit a participant from sending the same code several times?

[stetsko-andrew-v]

How can I prohibit a participant from sending the same code several times?

[Haozhe Xie]

What do you mean? I don't understand.

[stetsko-andrew-v]

We want to start contest on VOJ and we want to secure from DDoS and we want that contestant can't send one program code several times.

[Haozhe Xie]

The whole system is protected by CSRF.
I think the code may not be submitted several times.

[stetsko-andrew-v]

Yes, we know about CSRF. But we want that contestant can't send 2 or more time same code, becouse we want to use it in our school where pupils DDoS our site.

[Haozhe Xie]

But the button is disabled after submitting. How to submit the code more than once?
One solution is to compare the code with the previous ones. If the newly submitted code is the same as the previous one, ignore the code.
What do you think?

[stetsko-andrew-v]

The contestant can publish a partial solution and throw it several times and because of this voj.judger may not work (collapse)

[stetsko-andrew-v]

I have edited SubmissionService.java but can't compile(error)
SubmissionService.java:

private Map<String, ? extends Object> getSubmissionCreationResult(Submission submission, boolean isCsrfTokenValid) {
		Map<String, Boolean> result = new HashMap<>(6, 1);
		String code = submission.getCode();
		List submissionsofthisuser = getSubmissions(submission.getProblem(), submission.getUser().getUsername());
		Boolean isCodeLikePrevious = false;
		for (Submission submissionp : submissionsofthisuser){
			if(submissionp.getCode() == code){ isCodeLikePrevious = true; break;}
		}
		result.put("isUserLogined", submission.getUser() != null);
		result.put("isProblemExists", submission.getProblem() != null);
		result.put("isLanguageExists", submission.getLanguage() != null);
		result.put("isCodeEmpty", code == null || code.length() == 0);
		result.put("isCsrfTokenValid", isCsrfTokenValid);
		result.put("isCodeLikePrevious", isCodeLikePrevious);
		boolean isSuccessful = result.get("isUserLogined")	&&  result.get("isProblemExists") &&
							   result.get("isLanguageExists") && !result.get("isCodeEmpty")	 &&
							   result.get("isCsrfTokenValid") && !result.get("isCodeLikePrevious");
		result.put("isSuccessful", isSuccessful);
		return result;
	}

[Haozhe Xie]

Please provide the corresponding logs.

[Haozhe Xie]

Closed due to inactivity.