da9b0ddf5b
This should clear up some of the confusion with random number generators and drivers that obtain entropy from the hardware. Also, many hardware number generators have limited bandwidth, so it's natural for their output to be only used for seeding a random number generator. Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>
112 lines
2.5 KiB
C
112 lines
2.5 KiB
C
/*
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* Copyright (c) 2017 Intel Corporation.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <entropy.h>
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#include <ztest.h>
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/*
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* @addtogroup t_entropy_api
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* @{
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* @defgroup t_entropy_get_entropy test_entropy_get_entropy
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* @brief TestPurpose: verify Get entropy works
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* @details
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* - Test Steps
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* -# Read random numbers from Entropy driver.
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* -# Verify whether buffer overflow occurred or not.
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* -# Verify whether buffer completely filled or not.
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* - Expected Results
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* -# Random number should be generated.
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* @}
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*/
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#define BUFFER_LENGTH 10
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#define RECHECK_RANDOM_ENTROPY 0x10
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static int random_entropy(struct device *dev, char *buffer, char num)
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{
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int ret, i;
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int count = 0;
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memset(buffer, num, BUFFER_LENGTH);
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/* The BUFFER_LENGTH-1 is used so the driver will not
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* write the last byte of the buffer. If that last
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* byte is not 0 on return it means the driver wrote
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* outside the passed buffer, and that should never
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* happen.
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*/
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ret = entropy_get_entropy(dev, buffer, BUFFER_LENGTH - 1);
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if (ret) {
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TC_PRINT("Error: entropy_get_entropy failed: %d\n", ret);
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return TC_FAIL;
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}
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if (buffer[BUFFER_LENGTH - 1] != num) {
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TC_PRINT("Error: entropy_get_entropy buffer overflow\n");
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return TC_FAIL;
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}
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for (i = 0; i < BUFFER_LENGTH - 1; i++) {
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TC_PRINT(" 0x%02x\n", buffer[i]);
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if (buffer[i] == num) {
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count++;
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}
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}
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if (count >= 2) {
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return RECHECK_RANDOM_ENTROPY;
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} else {
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return TC_PASS;
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}
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}
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/*
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* Function invokes the get_entropy callback in driver
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* to get the random data and fill to passed buffer
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*/
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static int get_entropy(void)
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{
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struct device *dev;
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u8_t buffer[BUFFER_LENGTH] = { 0 };
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int ret;
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dev = device_get_binding(CONFIG_ENTROPY_NAME);
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if (!dev) {
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TC_PRINT("error: no random device\n");
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return TC_FAIL;
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}
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TC_PRINT("random device is %p, name is %s\n",
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dev, dev->config->name);
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ret = random_entropy(dev, buffer, 0);
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/* Check whether 20% or more of buffer still filled with default
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* value(0), if yes then recheck again by filling nonzero value(0xa5)
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* to buffer. Recheck random_entropy and verify whether 20% or more
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* of buffer filled with value(0xa5) or not.
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*/
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if (ret == RECHECK_RANDOM_ENTROPY) {
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ret = random_entropy(dev, buffer, 0xa5);
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if (ret == RECHECK_RANDOM_ENTROPY) {
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return TC_FAIL;
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} else {
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return ret;
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}
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}
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return ret;
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}
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static void test_entropy_get_entropy(void)
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{
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zassert_true(get_entropy() == TC_PASS, NULL);
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}
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void test_main(void)
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{
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ztest_test_suite(entropy_api,
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ztest_unit_test(test_entropy_get_entropy));
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ztest_run_test_suite(entropy_api);
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}
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