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fix(totp): handle negative time and refine rounding #36

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Merged
LimiNode merged 1 commit into from
Sep 4, 2025
Merged

fix(totp): handle negative time and refine rounding #36

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14 changes: 10 additions & 4 deletions hmac_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
std::time_t rounded = (now / interval_sec) * interval_sec;
std::time_t rounded = now - (now % interval_sec);
return get_hmac(key, std::to_string(rounded), hash_type);
}

Expand All @@ -39,7 +39,7 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
std::time_t rounded = (now / interval_sec) * interval_sec;
std::time_t rounded = now - (now % interval_sec);
if (constant_time_equals(token, get_hmac(key, std::to_string(rounded), hash_type))) return true;
if (rounded >= std::numeric_limits<std::time_t>::min() + interval_sec) {
if (constant_time_equals(token, get_hmac(key, std::to_string(rounded - interval_sec), hash_type))) return true;
Expand All @@ -59,7 +59,7 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
std::time_t rounded = (now / interval_sec) * interval_sec;
std::time_t rounded = now - (now % interval_sec);
std::string payload = std::to_string(rounded) + "|" + fingerprint;
return get_hmac(key, payload, hash_type);
}
Expand All @@ -73,7 +73,7 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
std::time_t rounded = (now / interval_sec) * interval_sec;
std::time_t rounded = now - (now % interval_sec);
std::string prefix = "|" + fingerprint;
std::string payload = std::to_string(rounded) + prefix;
if (constant_time_equals(token, get_hmac(key, payload, hash_type))) return true;
Expand Down Expand Up @@ -154,6 +154,9 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
if (now < 0) {
throw std::runtime_error("std::time returned negative value");
}
uint64_t timestamp = static_cast<uint64_t>(now);
return get_totp_code_at(key_ptr, key_len, timestamp, period, digits, hash_type);
}
Expand Down Expand Up @@ -203,6 +206,9 @@ namespace hmac {
if (now == static_cast<std::time_t>(-1) && errno != 0) {
throw std::runtime_error("std::time failed");
}
if (now < 0) {
throw std::runtime_error("std::time returned negative value");
}
uint64_t timestamp = static_cast<uint64_t>(now);
uint64_t counter = timestamp / period;
if (token == get_hotp_code(key_ptr, key_len, counter, digits, hash_type)) return true;
Expand Down
17 changes: 14 additions & 3 deletions test_all.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -215,16 +215,16 @@ TEST(TimeErrorTest, MinusOneWithErrno) {
mock_time_value = 0;
}

TEST(TotpTimeErrorTest, MinusOneNoErrno) {
TEST(TotpTimeErrorTest, NegativeTimeThrows) {
const std::string key = "12345";
mock_time_value = static_cast<std::time_t>(-1);
mock_errno_value = 0;
EXPECT_NO_THROW(hmac::get_totp_code(key));
EXPECT_THROW(hmac::get_totp_code(key), std::runtime_error);
mock_time_value = 0;
mock_errno_value = 0;
}

TEST(TotpTimeErrorTest, MinusOneWithErrno) {
TEST(TotpTimeErrorTest, NegativeTimeThrowsErrno) {
const std::string key = "12345";
mock_time_value = static_cast<std::time_t>(-1);
mock_errno_value = EINVAL;
Expand All @@ -233,6 +233,17 @@ TEST(TotpTimeErrorTest, MinusOneWithErrno) {
mock_time_value = 0;
}

TEST(TotpTimeErrorTest, ValidityNegativeTimeThrows) {
const std::string key = "12345";
mock_time_value = static_cast<std::time_t>(-1);
mock_errno_value = 0;
EXPECT_THROW(
hmac::is_totp_token_valid(0, key.data(), key.size(), 30, 6, hmac::TypeHash::SHA1),
std::runtime_error);
mock_time_value = 0;
mock_errno_value = 0;
}

int main(int argc, char **argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
Expand Down
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