dht: persist values with system time

Dht::onDisconnected() only starts a bootstrap when bootstrapJob is
unset, reading a set handle as "a bootstrap is already scheduled".
That reading is wrong: Scheduler::run() erases the job from its timers
and calls it, but never clears the shared handle the caller holds, and
Scheduler::cancel() leaves the handle alone too when the job is no
longer in the timers. The handle therefore stays set for as long as the
Dht lives, once a bootstrap job has run.

That is harmless while bootstrap() reschedules itself, which it does as
long as the node is disconnected. It is not harmless on the early
return: a job that fires while a ping is still in flight, or while a
dubious contact keeps the status at Connecting, returns without
rescheduling. From then on the chain is dead and onDisconnected() will
not restart it, so a node that goes on to lose every contact stays
disconnected for good. Only an explicit addBootstrap() or a
connectivityChanged() can revive it, and a node whose network simply
went away gets neither.

Clearing the handle on the early return restores the meaning
onDisconnected() relies on.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/python-wheels.yml

@@ -16,14 +16,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, ubuntu-24.04-arm, macos-latest]
+        os: [ubuntu-latest, ubuntu-24.04-arm, macos-15]
 
     steps:
       - uses: actions/checkout@v7
 
       # Run locally with: pipx run cibuildwheel --platform linux python
       - name: Build wheels
-        uses: pypa/cibuildwheel@v4.1.0
+        uses: pypa/cibuildwheel@v4.1.1
         with:
           package-dir: python
 

CMakeLists.txt

@@ -10,7 +10,7 @@ if(POLICY CMP0167)
 endif()
 
 set (opendht_VERSION_MAJOR 4)
-set (opendht_VERSION_MINOR 1.1)
+set (opendht_VERSION_MINOR 2.0)
 set (opendht_VERSION ${opendht_VERSION_MAJOR}.${opendht_VERSION_MINOR})
 set (PACKAGE_VERSION ${opendht_VERSION})
 set (VERSION "${opendht_VERSION}")

include/opendht/crypto.h

@@ -267,9 +267,14 @@ public:
     /**
      * Sign this revocation list using provided key and certificate.
      * Validity_period sets the duration until next update (default to no next update).
+     * If `number` is non-zero, it is stored verbatim (big-endian) as the CRL Number
+     * extension. Otherwise the number is initialized randomly on the first signature
+     * and incremented on subsequent ones.
      */
-    void sign(const PrivateKey&, const Certificate&, duration validity_period = {});
-    void sign(const Identity& id) { sign(*id.first, *id.second); }
+    void sign(const PrivateKey&, const Certificate&, duration validity_period = {}, uint64_t number = 0);
+    void sign(const Identity& id, duration validity_period = {}, uint64_t number = 0) {
+        sign(*id.first, *id.second, validity_period, number);
+    }
 
     bool isSignedBy(const Certificate& issuer) const;
 

include/opendht/utils.h

@@ -85,6 +85,14 @@ using system_clock = std::chrono::system_clock;
 using time_point = clock::time_point;
 using duration = clock::duration;
 
+OPENDHT_PUBLIC time_point from_system_time(system_clock::time_point t,
+                                           time_point steady_now,
+                                           system_clock::time_point system_now);
+OPENDHT_PUBLIC time_point from_system_time(system_clock::time_point t);
+OPENDHT_PUBLIC system_clock::time_point to_system_time(time_point t,
+                                                       time_point steady_now,
+                                                       system_clock::time_point system_now);
+OPENDHT_PUBLIC system_clock::time_point to_system_time(time_point t);
 OPENDHT_PUBLIC time_point from_time_t(std::time_t t);
 OPENDHT_PUBLIC std::time_t to_time_t(time_point t);
 

meson.build

@@ -5,7 +5,7 @@ project(
     'cython',
     license: 'MIT',
     license_files: 'LICENSE',
-    version: '4.1.1',
+    version: '4.2.0',
     meson_version: '>=1.1.0',
     default_options: ['cpp_std=c++20', 'warning_level=3'],
 )

src/crypto.cpp

@@ -571,6 +571,12 @@ PublicKey::toString() const
     }
     if (err != GNUTLS_E_SUCCESS)
         throw CryptoException(std::string("Could not print public key: ") + gnutls_strerror(err));
+    // GnuTLS reports the PEM size including the terminating null byte, which
+    // does not belong to the text and would end up embedded in whatever the
+    // string is copied into, such as the "owner" field of a serialized value.
+    ret.resize(sz);
+    if (not ret.empty() and ret.back() == '\0')
+        ret.pop_back();
     return ret;
 }
 
@@ -1396,8 +1402,11 @@ setRandomSerial(gnutls_x509_crt_t cert)
 {
     std::random_device rdev;
     std::uniform_int_distribution<int64_t> dist {1};
-    int64_t cert_serial = dist(rdev);
-    gnutls_x509_crt_set_serial(cert, &cert_serial, sizeof(cert_serial));
+    const auto cert_serial = dist(rdev);
+    std::array<uint8_t, sizeof(cert_serial)> packed_serial;
+    for (size_t i = 0; i < packed_serial.size(); i++)
+        packed_serial[i] = cert_serial >> (8 * (packed_serial.size() - 1 - i));
+    gnutls_x509_crt_set_serial(cert, packed_serial.data(), packed_serial.size());
 }
 
 Certificate
@@ -1873,34 +1882,8 @@ RevocationList::getUpdateTime() const
     return std::chrono::system_clock::from_time_t(t);
 }
 
-enum class Endian : uint32_t { LITTLE = 0, BIG = 1 };
-
-template<typename T>
-T
-endian(T w, Endian endian = Endian::BIG)
-{
-    // this gets optimized out into if (endian == host_endian) return w;
-    union {
-        uint64_t quad;
-        uint32_t islittle;
-    } t;
-    t.quad = 1;
-    if (t.islittle ^ (uint32_t) endian)
-        return w;
-    T r = 0;
-
-    // decent compilers will unroll this (gcc)
-    // or even convert straight into single bswap (clang)
-    for (size_t i = 0; i < sizeof(r); i++) {
-        r <<= 8;
-        r |= w & 0xff;
-        w >>= 8;
-    }
-    return r;
-}
-
 void
-RevocationList::sign(const PrivateKey& key, const Certificate& ca, duration validity)
+RevocationList::sign(const PrivateKey& key, const Certificate& ca, duration validity, uint64_t crlNumber)
 {
     if (auto err = gnutls_x509_crl_set_version(crl, 2))
         throw CryptoException(std::string("Unable to set CRL version: ") + gnutls_strerror(err));
@@ -1910,19 +1893,28 @@ RevocationList::sign(const PrivateKey& key, const Certificate& ca, duration vali
         throw CryptoException(std::string("Unable to set CRL update time: ") + gnutls_strerror(err));
     if (auto err = gnutls_x509_crl_set_next_update(crl, std::chrono::system_clock::to_time_t(next_update)))
         throw CryptoException(std::string("Unable to set CRL next update time: ") + gnutls_strerror(err));
-    uint64_t number {0};
-    size_t number_sz {sizeof(number)};
-    unsigned critical {0};
-    gnutls_x509_crl_get_number(crl, &number, &number_sz, &critical);
+    uint64_t number {crlNumber};
     if (number == 0) {
-        // initialize to a random number
-        number_sz = sizeof(number);
-        std::random_device rdev;
-        std::generate_n((uint8_t*) &number, sizeof(number), std::bind(rand_byte, std::ref(rdev)));
-    } else
-        number = endian(endian(number) + 1);
-    if (auto err = gnutls_x509_crl_set_number(crl, &number, sizeof(number)))
-        throw CryptoException(std::string("Unable to set CRL update time: ") + gnutls_strerror(err));
+        // The CRL Number extension holds a DER integer of variable length, so it must be
+        // read as a big-endian byte string rather than straight into an uint64_t.
+        auto current = getNumber();
+        for (uint8_t byte : current)
+            number = (number << 8) | byte;
+        if (number == 0) {
+            // Initialize to a random number.
+            std::random_device rdev;
+            do {
+                std::generate_n((uint8_t*) &number, sizeof(number), std::bind(rand_byte, std::ref(rdev)));
+            } while (number == 0);
+        } else
+            number++;
+    }
+    // Store the number in network byte order.
+    uint8_t packedNumber[sizeof(number)];
+    for (size_t i = 0; i < sizeof(packedNumber); i++)
+        packedNumber[i] = (uint8_t) ((number >> (8 * (sizeof(packedNumber) - 1 - i))) & 0xff);
+    if (auto err = gnutls_x509_crl_set_number(crl, packedNumber, sizeof(packedNumber)))
+        throw CryptoException(std::string("Unable to set CRL number: ") + gnutls_strerror(err));
     if (auto err = gnutls_x509_crl_sign2(crl, ca.cert, key.x509_key, GNUTLS_DIG_SHA512, 0))
         throw CryptoException(std::string("Unable to sign certificate revocation list: ") + gnutls_strerror(err));
     // to be able to actually use the CRL we need to serialize/deserialize it

src/dht.cpp

@@ -2270,8 +2270,16 @@ Dht::onDisconnected()
 void
 Dht::bootstrap()
 {
-    if (dht4.status != NodeStatus::Disconnected || dht6.status != NodeStatus::Disconnected)
+    if (dht4.status != NodeStatus::Disconnected || dht6.status != NodeStatus::Disconnected) {
+        // The job that led here has already run, and the scheduler does not
+        // clear the handle to a job it has executed. onDisconnected() reads a
+        // set handle as "a bootstrap is already scheduled" and does nothing,
+        // so leaving it set here means the node never tries to rejoin the
+        // network once it has lost it. Clearing it is what says that no
+        // bootstrap is pending any more.
+        bootstrapJob.reset();
         return;
+    }
     if (logger_)
         logger_->debug("[{}] Bootstraping", myid.to_view());
     bootstrap_pending = false;
@@ -2355,6 +2363,9 @@ Dht::confirmNodes()
 std::vector<ValuesExport>
 Dht::exportValues() const
 {
+    const auto& now = scheduler.time();
+    const auto system_now = system_clock::now();
+
     std::vector<ValuesExport> e {};
     e.reserve(store.size());
     for (const auto& h : store) {
@@ -2367,7 +2378,7 @@ Dht::exportValues() const
         pk.pack_array(vals.size());
         for (const auto& v : vals) {
             pk.pack_array(4);
-            pk.pack(v.created.time_since_epoch().count());
+            pk.pack(to_system_time(v.created, now, system_now));
             v.data->msgpack_pack(pk);
             if (const auto& store_addr = v.store_bucket ? v.store_bucket->getAddr() : SockAddr {}) {
                 pk.pack_bin(store_addr.getLength());
@@ -2375,7 +2386,7 @@ Dht::exportValues() const
             } else {
                 pk.pack_bin(0);
             }
-            pk.pack(v.expiration.time_since_epoch().count());
+            pk.pack(to_system_time(v.expiration, now, system_now));
         }
         ve.second = {buffer.data(), buffer.data() + buffer.size()};
         e.push_back(std::move(ve));
@@ -2387,6 +2398,7 @@ void
 Dht::importValues(const std::vector<ValuesExport>& import)
 {
     const auto& now = scheduler.time();
+    const auto system_now = system_clock::now();
 
     unsigned imported = 0, ignored = 0;
     size_t imported_size = 0;
@@ -2411,8 +2423,15 @@ Dht::importValues(const std::vector<ValuesExport>& import)
                 Value tmp_val;
                 SockAddr store_addr;
                 try {
-                    val_time = time_point {
-                        time_point::duration {valel.via.array.ptr[0].as<time_point::duration::rep>()}};
+                    const bool uses_system_time = valel.via.array.ptr[0].type == msgpack::type::EXT;
+                    if (uses_system_time) {
+                        val_time = from_system_time(valel.via.array.ptr[0].as<system_clock::time_point>(),
+                                                    now,
+                                                    system_now);
+                    } else {
+                        val_time = time_point {
+                            time_point::duration {valel.via.array.ptr[0].as<time_point::duration::rep>()}};
+                    }
                     tmp_val.msgpack_unpack(valel.via.array.ptr[1]);
                     if (valel.via.array.size >= 3) {
                         auto addr_blob = valel.via.array.ptr[2].as<Blob>();
@@ -2422,8 +2441,14 @@ Dht::importValues(const std::vector<ValuesExport>& import)
                         }
                     }
                     if (valel.via.array.size >= 4) {
-                        expiration = time_point {
-                            time_point::duration {valel.via.array.ptr[3].as<time_point::duration::rep>()}};
+                        if (uses_system_time) {
+                            expiration = from_system_time(valel.via.array.ptr[3].as<system_clock::time_point>(),
+                                                          now,
+                                                          system_now);
+                        } else {
+                            expiration = time_point {
+                                time_point::duration {valel.via.array.ptr[3].as<time_point::duration::rep>()}};
+                        }
                     }
                 } catch (const std::exception&) {
                     if (logger_)

src/http.cpp

@@ -302,7 +302,7 @@ static X509*
 issuer_from_chain(STACK_OF(X509) * fullchain)
 {
     X509 *cert, *issuer;
-    X509_NAME* issuer_name;
+    const X509_NAME* issuer_name;
 
     cert = cert_from_chain(fullchain);
     if ((issuer_name = X509_get_issuer_name(cert)) == nullptr)
@@ -917,8 +917,16 @@ Resolver::add_callback(ResolverCb cb, sa_family_t family)
                                                else
                                                    cb(ec, filter(endpoints, family));
                                            });
-    else
-        cb(ec_, family == AF_UNSPEC ? endpoints_ : filter(endpoints_, family));
+    else {
+        // Always dispatch the callback on the io_context thread. Invoking it
+        // synchronously would run the caller's continuation (e.g. the whole
+        // connect chain of Request::send) on the calling thread, mutating asio
+        // objects concurrently with the io thread running the io_context.
+        asio::post(resolver_.get_executor(),
+                   [cb = std::move(cb),
+                    ec = ec_,
+                    endpoints = family == AF_UNSPEC ? endpoints_ : filter(endpoints_, family)] { cb(ec, endpoints); });
+    }
 }
 
 void

src/utils.cpp

@@ -238,28 +238,58 @@ operator==(const SockAddr& a, const SockAddr& b)
     return a.equals(b);
 }
 
+time_point
+from_system_time(system_clock::time_point t, time_point steady_now, system_clock::time_point system_now)
+{
+    if (t == system_clock::time_point::min())
+        return time_point::min();
+    if (t == system_clock::time_point::max())
+        return time_point::max();
+    auto dt = t - system_now;
+    if (dt > system_clock::duration(0) and steady_now > time_point::max() - dt)
+        return time_point::max();
+    else if (dt < system_clock::duration(0) and steady_now < time_point::min() - dt)
+        return time_point::min();
+    return steady_now + dt;
+}
+
+time_point
+from_system_time(system_clock::time_point t)
+{
+    return from_system_time(t, clock::now(), system_clock::now());
+}
+
+system_clock::time_point
+to_system_time(time_point t, time_point steady_now, system_clock::time_point system_now)
+{
+    if (t == time_point::min())
+        return system_clock::time_point::min();
+    if (t == time_point::max())
+        return system_clock::time_point::max();
+    auto dt = t - steady_now;
+    if (dt > duration(0) and system_now >= system_clock::time_point::max() - dt)
+        return system_clock::time_point::max();
+    else if (dt < duration(0) and system_now <= system_clock::time_point::min() - dt)
+        return system_clock::time_point::min();
+    return system_now + std::chrono::duration_cast<system_clock::duration>(dt);
+}
+
+system_clock::time_point
+to_system_time(time_point t)
+{
+    return to_system_time(t, clock::now(), system_clock::now());
+}
+
 time_point
 from_time_t(std::time_t t)
 {
-    auto dt = system_clock::from_time_t(t) - system_clock::now();
-    auto now = clock::now();
-    if (dt > system_clock::duration(0) and now > time_point::max() - dt)
-        return time_point::max();
-    else if (dt < system_clock::duration(0) and now < time_point::min() - dt)
-        return time_point::min();
-    return now + dt;
+    return from_system_time(system_clock::from_time_t(t));
 }
 
 std::time_t
 to_time_t(time_point t)
 {
-    auto dt = t - clock::now();
-    auto now = system_clock::now();
-    if (dt > duration(0) and now >= system_clock::time_point::max() - dt)
-        return system_clock::to_time_t(system_clock::time_point::max());
-    else if (dt < duration(0) and now <= system_clock::time_point::min() - dt)
-        return system_clock::to_time_t(system_clock::time_point::min());
-    return system_clock::to_time_t(now + std::chrono::duration_cast<system_clock::duration>(dt));
+    return system_clock::to_time_t(to_system_time(t));
 }
 
 Blob

tests/test_crypto.cpp

@@ -59,6 +59,24 @@ CryptoTester::testSignatureEncryption()
     }
 }
 
+void
+CryptoTester::testPublicKeyPemIsPlainText()
+{
+    auto key = dht::crypto::PrivateKey::generate();
+    auto pem = key.getPublicKey().toString();
+
+    // The exported key is PEM text: it must not carry the terminating null
+    // byte GnuTLS counts in the exported size, which would otherwise be
+    // embedded in anything the string is serialized into.
+    CPPUNIT_ASSERT(not pem.empty());
+    CPPUNIT_ASSERT_EQUAL(std::string::npos, pem.find('\0'));
+    CPPUNIT_ASSERT_EQUAL('\n', pem.back());
+
+    // The exported text still reads back as the same key.
+    dht::crypto::PublicKey reloaded(dht::Blob(pem.begin(), pem.end()));
+    CPPUNIT_ASSERT_EQUAL(key.getPublicKey().getId(), reloaded.getId());
+}
+
 void
 CryptoTester::testCertificateRevocation()
 {
@@ -95,10 +113,159 @@ CryptoTester::testCertificateRevocation()
     CPPUNIT_ASSERT_MESSAGE(v.toString(), v);
 }
 
+namespace {
+
+/** Read a CRL Number extension blob (big-endian, variable length) as an integer. */
+uint64_t
+crlNumberValue(const dht::Blob& number)
+{
+    uint64_t value {0};
+    for (uint8_t byte : number)
+        value = (value << 8) | byte;
+    return value;
+}
+
+} // namespace
+
+void
+CryptoTester::testRevocationListNumber()
+{
+    auto ca = dht::crypto::generateIdentity("ca");
+    auto device = dht::crypto::generateIdentity("dev", ca);
+
+    dht::crypto::RevocationList crl;
+    CPPUNIT_ASSERT_EQUAL(uint64_t(0), crlNumberValue(crl.getNumber()));
+
+    crl.revoke(*device.second);
+    crl.sign(ca);
+    auto first = crl.getNumber();
+    // An unnumbered list gets a random number on its first signature.
+    CPPUNIT_ASSERT(not first.empty());
+    CPPUNIT_ASSERT(crlNumberValue(first) != 0);
+
+    // Re-signing keeps the same lineage and moves the number forward.
+    crl.sign(ca);
+    auto second = crl.getNumber();
+    CPPUNIT_ASSERT_EQUAL(crlNumberValue(first) + 1, crlNumberValue(second));
+
+    crl.sign(ca);
+    CPPUNIT_ASSERT_EQUAL(crlNumberValue(first) + 2, crlNumberValue(crl.getNumber()));
+
+    // The number is a DER integer, so it is stored with leading zeros stripped.
+    // Incrementing must still work for numbers shorter than 8 bytes.
+    for (uint64_t start : {uint64_t(1), uint64_t(0x7f), uint64_t(0x80), uint64_t(0xffff)}) {
+        dht::crypto::RevocationList small;
+        small.revoke(*device.second);
+        small.sign(ca, {}, start);
+        CPPUNIT_ASSERT_EQUAL(start, crlNumberValue(small.getNumber()));
+        small.sign(ca);
+        CPPUNIT_ASSERT_EQUAL(start + 1, crlNumberValue(small.getNumber()));
+        small.sign(ca);
+        CPPUNIT_ASSERT_EQUAL(start + 2, crlNumberValue(small.getNumber()));
+    }
+}
+
+void
+CryptoTester::testRevocationListExplicitNumber()
+{
+    auto ca = dht::crypto::generateIdentity("ca");
+    auto device = dht::crypto::generateIdentity("dev", ca);
+
+    // Values chosen to cover leading zero bytes, a full-width number and the largest
+    // value that still encodes as a positive 8-byte DER integer.
+    const std::vector<uint64_t> numbers {1,
+                                         42,
+                                         0xff,
+                                         0x100,
+                                         0x0000'0001'0000'0000ull,
+                                         0x0000'02a1'0000'0001ull,
+                                         0x7fff'ffff'ffff'ffffull};
+    for (auto number : numbers) {
+        dht::crypto::RevocationList crl;
+        crl.revoke(*device.second);
+        crl.sign(ca, {}, number);
+        CPPUNIT_ASSERT_EQUAL(number, crlNumberValue(crl.getNumber()));
+        CPPUNIT_ASSERT(crl.isSignedBy(*ca.second));
+        CPPUNIT_ASSERT(crl.isRevoked(*device.second));
+
+        // The number must survive a pack/unpack round-trip.
+        dht::crypto::RevocationList unpacked(crl.getPacked());
+        CPPUNIT_ASSERT_EQUAL(number, crlNumberValue(unpacked.getNumber()));
+    }
+
+    // An explicit number overrides the increment, in both directions.
+    dht::crypto::RevocationList crl;
+    crl.revoke(*device.second);
+    crl.sign(ca, {}, 1000);
+    CPPUNIT_ASSERT_EQUAL(uint64_t(1000), crlNumberValue(crl.getNumber()));
+    crl.sign(ca, {}, 5);
+    CPPUNIT_ASSERT_EQUAL(uint64_t(5), crlNumberValue(crl.getNumber()));
+
+    // Passing 0 falls back to the default behavior: increment the current number.
+    crl.sign(ca, {}, 0);
+    CPPUNIT_ASSERT_EQUAL(uint64_t(6), crlNumberValue(crl.getNumber()));
+}
+
+void
+CryptoTester::testRevocationListPartitionedNumber()
+{
+    // Two devices holding the same authority issue revocation lists independently.
+    // RFC 5280 5.2.3 requires CRL numbers to increase monotonically for a given CRL
+    // scope and issuer; partitioning the low bits by device keeps each sequence
+    // monotonic while making collisions between devices impossible.
+    constexpr unsigned TAG_BITS = 24;
+    constexpr uint64_t TAG_A = 0x0a0b0c;
+    constexpr uint64_t TAG_B = 0x0a0b0d;
+
+    auto ca = dht::crypto::generateIdentity("ca");
+    auto account = dht::crypto::generateIdentity("acc", ca, 4096, true);
+    auto deviceA = dht::crypto::generateIdentity("devA", account);
+    auto deviceB = dht::crypto::generateIdentity("devB", account);
+
+    uint64_t previous {0};
+    dht::crypto::RevocationList crlA;
+    for (unsigned i = 1; i <= 4; i++) {
+        crlA.revoke(*deviceA.second);
+        crlA.sign(account, {}, (uint64_t(i) << TAG_BITS) | TAG_A);
+        auto number = crlNumberValue(crlA.getNumber());
+        CPPUNIT_ASSERT_EQUAL(TAG_A, number & ((uint64_t(1) << TAG_BITS) - 1));
+        CPPUNIT_ASSERT(number > previous);
+        CPPUNIT_ASSERT_EQUAL(uint64_t(0), number >> 63);
+        previous = number;
+    }
+
+    // Both devices branch from the same counter but never mint the same number.
+    dht::crypto::RevocationList branchA;
+    branchA.revoke(*deviceA.second);
+    branchA.sign(account, {}, (uint64_t(9) << TAG_BITS) | TAG_A);
+    dht::crypto::RevocationList branchB;
+    branchB.revoke(*deviceB.second);
+    branchB.sign(account, {}, (uint64_t(9) << TAG_BITS) | TAG_B);
+    CPPUNIT_ASSERT(crlNumberValue(branchA.getNumber()) != crlNumberValue(branchB.getNumber()));
+
+    // Both are valid and revoke only their own target.
+    CPPUNIT_ASSERT(branchA.isSignedBy(*account.second));
+    CPPUNIT_ASSERT(branchB.isSignedBy(*account.second));
+    CPPUNIT_ASSERT(branchA.isRevoked(*deviceA.second));
+    CPPUNIT_ASSERT(not branchA.isRevoked(*deviceB.second));
+    CPPUNIT_ASSERT(branchB.isRevoked(*deviceB.second));
+    CPPUNIT_ASSERT(not branchB.isRevoked(*deviceA.second));
+
+    // A number minted by an older client is fully random, so bit 63 may be set. Masking
+    // it out and taking the counter part still yields a strictly greater number.
+    constexpr uint64_t legacy = 0xdead'beef'0123'4567ull;
+    dht::crypto::RevocationList legacyCrl;
+    legacyCrl.revoke(*deviceA.second);
+    legacyCrl.sign(account, {}, legacy);
+    auto counter = ((crlNumberValue(legacyCrl.getNumber()) & ~(uint64_t(1) << 63)) >> TAG_BITS) + 1;
+    legacyCrl.sign(account, {}, (counter << TAG_BITS) | TAG_A);
+    CPPUNIT_ASSERT(crlNumberValue(legacyCrl.getNumber()) > (legacy & ~(uint64_t(1) << 63)));
+    CPPUNIT_ASSERT_EQUAL(uint64_t(0), crlNumberValue(legacyCrl.getNumber()) >> 63);
+}
+
 void
 CryptoTester::testCertificateRequest()
-{
-    // Generate CA
+{    // Generate CA
     auto ca = dht::crypto::generateIdentity("Test CA");
 
     // Generate signed request
@@ -149,6 +316,15 @@ CryptoTester::testCertificateSerialNumber()
     };
     auto serial = dht::crypto::Certificate(cert_pem).getSerialNumber();
     CPPUNIT_ASSERT(std::equal(SERIAL.begin(), SERIAL.end(), serial.begin(), serial.end()));
+
+    auto key = dht::crypto::PrivateKey::generateEC();
+    for (unsigned i = 0; i < 32; i++) {
+        auto generated = dht::crypto::Certificate::generate(key, "generated", {});
+        auto generatedSerial = generated.getSerialNumber();
+        CPPUNIT_ASSERT(not generatedSerial.empty());
+        CPPUNIT_ASSERT_EQUAL(uint8_t {0}, uint8_t(generatedSerial.front() & 0x80));
+        CPPUNIT_ASSERT(std::any_of(generatedSerial.begin(), generatedSerial.end(), [](uint8_t byte) { return byte != 0; }));
+    }
 }
 
 void

tests/test_crypto.h

@@ -12,7 +12,11 @@ class CryptoTester : public CppUnit::TestFixture
 {
     CPPUNIT_TEST_SUITE(CryptoTester);
     CPPUNIT_TEST(testSignatureEncryption);
+    CPPUNIT_TEST(testPublicKeyPemIsPlainText);
     CPPUNIT_TEST(testCertificateRevocation);
+    CPPUNIT_TEST(testRevocationListNumber);
+    CPPUNIT_TEST(testRevocationListExplicitNumber);
+    CPPUNIT_TEST(testRevocationListPartitionedNumber);
     CPPUNIT_TEST(testCertificateRequest);
     CPPUNIT_TEST(testCertificateSerialNumber);
     CPPUNIT_TEST(testOcsp);
@@ -36,10 +40,26 @@ public:
      * Test data signature, encryption and decryption
      */
     void testSignatureEncryption();
+    /**
+     * Test that an exported public key is text only, with no embedded null byte
+     */
+    void testPublicKeyPemIsPlainText();
     /**
      * Test certificate generation, validation and revocation
      */
     void testCertificateRevocation();
+    /**
+     * Test the default CRL Number behavior: random on first signature, incremented after
+     */
+    void testRevocationListNumber();
+    /**
+     * Test signing a revocation list with a caller-provided CRL Number
+     */
+    void testRevocationListExplicitNumber();
+    /**
+     * Test that issuers sharing an authority can partition the CRL Number space
+     */
+    void testRevocationListPartitionedNumber();
     /**
      * Test certificate requests
      */

tests/test_dhtrunner.cpp

@@ -210,6 +210,42 @@ DhtRunnerTester::testImportValuesPreservesRemoteQuota()
     restored.join();
 }
 
+void
+DhtRunnerTester::testExportValuesUsesSystemTime()
+{
+    auto key = dht::InfoHash::get("export-system-time");
+    const auto created = dht::clock::now();
+    msgpack::sbuffer importBuffer;
+    msgpack::packer<msgpack::sbuffer> pk(&importBuffer);
+    pk.pack_array(1);
+    pk.pack_array(2);
+    pk.pack(created.time_since_epoch().count());
+    dht::Value {std::string("persisted")}.msgpack_pack(pk);
+    node1.importValues({
+        dht::ValuesExport {key, {importBuffer.data(), importBuffer.data() + importBuffer.size()}}
+    });
+
+    auto exported = node1.exportValues();
+    CPPUNIT_ASSERT_EQUAL(size_t(1), exported.size());
+
+    msgpack::unpacked msg;
+    msgpack::unpack(msg, reinterpret_cast<const char*>(exported.front().second.data()), exported.front().second.size());
+    const auto values = msg.get();
+    CPPUNIT_ASSERT(values.type == msgpack::type::ARRAY);
+    CPPUNIT_ASSERT_EQUAL(uint32_t(1), values.via.array.size);
+    const auto& persistedValue = values.via.array.ptr[0];
+    CPPUNIT_ASSERT_EQUAL(uint32_t(4), persistedValue.via.array.size);
+    CPPUNIT_ASSERT(persistedValue.via.array.ptr[0].type == msgpack::type::EXT);
+    CPPUNIT_ASSERT(persistedValue.via.array.ptr[3].type == msgpack::type::EXT);
+
+    const auto persistedCreated = persistedValue.via.array.ptr[0].as<std::chrono::system_clock::time_point>();
+    const auto persistedExpiration = persistedValue.via.array.ptr[3].as<std::chrono::system_clock::time_point>();
+    const auto delta = std::chrono::system_clock::now() - persistedCreated;
+    CPPUNIT_ASSERT(delta >= std::chrono::system_clock::duration::zero());
+    CPPUNIT_ASSERT(delta < 5s);
+    CPPUNIT_ASSERT(persistedExpiration > persistedCreated);
+}
+
 void
 DhtRunnerTester::testImportValuesPreservesStoredExpiration()
 {

tests/test_dhtrunner.h

@@ -21,6 +21,7 @@ class DhtRunnerTester : public CppUnit::TestFixture
     CPPUNIT_TEST(testListenLotOfBytes);
     CPPUNIT_TEST(testIdOps);
     CPPUNIT_TEST(testImportValuesPreservesRemoteQuota);
+    CPPUNIT_TEST(testExportValuesUsesSystemTime);
     CPPUNIT_TEST(testImportValuesPreservesStoredExpiration);
     CPPUNIT_TEST(testImportPermanentValueExpires);
     CPPUNIT_TEST(testBootstrapSetsConnectingState);
@@ -67,6 +68,7 @@ public:
      */
     void testIdOps();
     void testImportValuesPreservesRemoteQuota();
+    void testExportValuesUsesSystemTime();
     void testImportValuesPreservesStoredExpiration();
     void testImportPermanentValueExpires();
     void testBootstrapSetsConnectingState();

tests/test_http.cpp

@@ -8,6 +8,7 @@
 
 #include <iostream>
 #include <string>
+#include <atomic>
 #include <chrono>
 #include <condition_variable>
 
@@ -332,6 +333,36 @@ HttpTester::test_parse_url_just_slash()
     CPPUNIT_ASSERT_EQUAL(std::string("/"), parsed.target);
 }
 
+void
+HttpTester::test_completed_resolver_callback_uses_io_thread()
+{
+    asio::io_context ioContext;
+    const asio::ip::tcp::endpoint endpoint(asio::ip::address_v4::loopback(), 80);
+    dht::http::Resolver resolver(ioContext, {endpoint});
+    const auto callerThread = std::this_thread::get_id();
+    std::thread::id callbackThread;
+    asio::error_code callbackError;
+    std::vector<asio::ip::tcp::endpoint> resolvedEndpoints;
+    std::atomic_bool callbackCalled {false};
+
+    resolver.add_callback([&](const asio::error_code& ec, const auto& endpoints) {
+        callbackError = ec;
+        callbackThread = std::this_thread::get_id();
+        resolvedEndpoints = endpoints;
+        callbackCalled = true;
+    });
+
+    CPPUNIT_ASSERT(!callbackCalled);
+    std::thread ioThread([&] { ioContext.run(); });
+    ioThread.join();
+
+    CPPUNIT_ASSERT(callbackCalled);
+    CPPUNIT_ASSERT(!callbackError);
+    CPPUNIT_ASSERT(callbackThread != callerThread);
+    CPPUNIT_ASSERT_EQUAL(size_t(1), resolvedEndpoints.size());
+    CPPUNIT_ASSERT_EQUAL(endpoint, resolvedEndpoints.front());
+}
+
 void
 HttpTester::test_send_json()
 {

tests/test_http.h

@@ -39,6 +39,7 @@ class HttpTester : public CppUnit::TestFixture
     CPPUNIT_TEST(test_parse_url_complex_path_query_fragment);
     CPPUNIT_TEST(test_parse_url_empty);
     CPPUNIT_TEST(test_parse_url_just_slash);
+    CPPUNIT_TEST(test_completed_resolver_callback_uses_io_thread);
     // send
     CPPUNIT_TEST(test_send_json);
     CPPUNIT_TEST_SUITE_END();
@@ -82,6 +83,7 @@ public:
     void test_parse_url_complex_path_query_fragment();
     void test_parse_url_empty();
     void test_parse_url_just_slash();
+    void test_completed_resolver_callback_uses_io_thread();
     /**
      * Test send(json)
      */

vcpkg.json

@@ -1,6 +1,6 @@
 {
   "name": "opendht",
-  "version-string": "4.1.1",
+  "version-string": "4.2.0",
   "port-version": 1,
   "description": "OpenDHT: A lightweight C++17 Distributed Hash Table library.",
   "homepage": "https://opendht.net",