// Copyright 2005-2017 The Mumble Developers. All rights reserved.
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file at the root of the
// Mumble source tree or at <https://www.mumble.info/LICENSE>.

#include <QtCore>
#include <QtTest>

#include "CryptographicRandom.h"

#include <stdint.h>
#include <stdlib.h>
#include <limits>

class TestCryptographicRandom : public QObject {
		Q_OBJECT
	private slots:
		void fillBuffer();
		void uint32();
		void uniform();
};

// Verify the entropy of the data returned by the random source
// by zlib compressing it and ensuring the compressed size is at
// least 99% of the size of the input data.
//
// The inspiration for this check is from the rand_test.go file
// for Go standard library's crypt/rand package:
// https://golang.org/src/crypto/rand/rand_test.go
bool verifyEntropy(unsigned char *buf, int len) {
	QByteArray flated = qCompress(buf, len);
	return (flated.size() >= ((len * 99) / 100));
}

void TestCryptographicRandom::fillBuffer() {
	const int buflen = 1000000;

	for (int i = 0; i < 10; i++) {
		unsigned char *buf = reinterpret_cast<unsigned char *>(calloc(buflen, 1));
		CryptographicRandom::fillBuffer(buf, buflen);
		QVERIFY(verifyEntropy(buf, buflen));
		free(buf);
	}
}

void TestCryptographicRandom::uint32() {
	const int buflen = 1000000;

	for (int i = 0; i < 10; i++) {
		unsigned char *buf = reinterpret_cast<unsigned char *>(calloc(buflen, 1));
		int niter = buflen / sizeof(uint32_t);
		for (int j = 0; j < niter; j++) {
			int off = j * sizeof(uint32_t);
			uint32_t val = CryptographicRandom::uint32();
			buf[off] = val & 0xff;
			buf[off+1] = (val >> 8) & 0xff;
			buf[off+2] = (val >> 16) & 0xff;
			buf[off+3] = (val >> 24) & 0xff;
		}
		QVERIFY(verifyEntropy(buf, buflen));
		free(buf);
	}
}

void TestCryptographicRandom::uniform() {
	for (uint32_t upperBound = 0; upperBound < 10000; upperBound++) {
		uint32_t val = CryptographicRandom::uniform(upperBound);
		QVERIFY(val <= upperBound);
	}
}


QTEST_MAIN(TestCryptographicRandom)
#include "TestCryptographicRandom.moc"
