Skip to content

Avoid using srand/rand for client_key generation (#324) #348

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
paneendrakumar0 wants to merge 1 commit into
base: rolling
Choose a base branch
from
Open

Avoid using srand/rand for client_key generation (#324) #348

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
27 changes: 22 additions & 5 deletions rmw_microxrcedds_c/src/rmw_init.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,27 @@

extern rmw_uxrce_transport_params_t rmw_uxrce_transport_default_params;

static uint32_t
generate_client_key(void)
{
static uint32_t state = 0;
int64_t now = uxr_nanos();
uint32_t entropy = (uint32_t)(now ^ (now >> 32));
state ^= entropy;
if (state == 0) {
state = 0x1337BEEF;
}
uint32_t key;
do {
// 32-bit Marsaglia xorshift PRNG (zero dynamic memory allocation)
state ^= state << 13;
state ^= state >> 17;
state ^= state << 5;
key = state;
} while (key == 0);
return key;
}

rmw_ret_t
rmw_init_options_init(
rmw_init_options_t * init_options,
Expand Down Expand Up @@ -108,11 +129,7 @@ rmw_init_options_init(
init_options->impl->transport_params.read_cb = rmw_uxrce_transport_default_params.read_cb;
#endif /* if defined(RMW_UXRCE_TRANSPORT_SERIAL) */

srand(uxr_nanos());

do {
init_options->impl->transport_params.client_key = rand(); //NOLINT
} while (init_options->impl->transport_params.client_key == 0);
init_options->impl->transport_params.client_key = generate_client_key();

return RMW_RET_OK;
}
Expand Down
26 changes: 26 additions & 0 deletions rmw_microxrcedds_c/test/test_rmw.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#include <rmw/init_options.h>
#include <rcutils/allocator.h>
#include <rmw_microros/rmw_microros.h>
#include <rmw_microros_internal/types.h>

#include <ctime>

Expand Down Expand Up @@ -92,3 +93,28 @@ TEST(rmw_microxrcedds, sync_session)
ASSERT_EQ(rmw_init_options_fini(&test_options), RMW_RET_OK);
ASSERT_EQ(rmw_shutdown(&test_context), RMW_RET_OK);
}

/*
* Testing client_key generation in rmw_init_options_init. https://github.com/micro-ROS/rmw_microxrcedds/issues/324
*/
TEST(rmw_microxrcedds, client_key_generation)
{
rmw_init_options_t options1 = rmw_get_zero_initialized_init_options();
rmw_init_options_t options2 = rmw_get_zero_initialized_init_options();

ASSERT_EQ(rmw_init_options_init(&options1, rcutils_get_default_allocator()), RMW_RET_OK);
ASSERT_EQ(rmw_init_options_init(&options2, rcutils_get_default_allocator()), RMW_RET_OK);

EXPECT_NE(options1.impl->transport_params.client_key, 0u);
EXPECT_NE(options2.impl->transport_params.client_key, 0u);
EXPECT_NE(options1.impl->transport_params.client_key, options2.impl->transport_params.client_key);

rmw_init_options_t options_copy = rmw_get_zero_initialized_init_options();
ASSERT_EQ(rmw_init_options_copy(&options1, &options_copy), RMW_RET_OK);
EXPECT_EQ(options_copy.impl->transport_params.client_key,
options1.impl->transport_params.client_key);

ASSERT_EQ(rmw_init_options_fini(&options_copy), RMW_RET_OK);
ASSERT_EQ(rmw_init_options_fini(&options1), RMW_RET_OK);
ASSERT_EQ(rmw_init_options_fini(&options2), RMW_RET_OK);
}