Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/security/v2/validity_restriction.cpp

@@ -0,0 +1,223 @@
+#include <vanetza/security/exception.hpp>
+#include <vanetza/security/v2/validity_restriction.hpp>
+
+namespace vanetza
+{
+namespace security
+{
+namespace v2
+{
+
+Duration::Duration() : m_raw(0)
+{
+}
+
+Duration::Duration(BitNumber<uint16_t, 13> value, Units unit) :
+    m_raw(static_cast<decltype(m_raw)>(unit))
+{
+    m_raw <<= 13;
+    m_raw |= value.raw();
+}
+
+Duration::Duration(uint16_t raw) : m_raw(raw)
+{
+}
+
+std::chrono::seconds Duration::to_seconds() const
+{
+    using std::chrono::seconds;
+
+    // see section 4.2.17 of TS 103 097 v1.2.1 for conversion factors
+    switch (unit()) {
+        case Units::Seconds:
+            return seconds(value());
+
+        case Units::Minutes:
+            return seconds(value() * 60U);
+
+        case Units::Hours:
+            return seconds(value() * 3600U);
+
+        case Units::Sixty_Hour_Blocks:
+            return seconds(value() * 216000U);
+
+        case Units::Years:
+            return seconds(value() * 31556925ULL);
+
+        default:
+            // undefined, let's interpret it as minimal duration, which will fail during validation
+            return std::chrono::seconds::min();
+    }
+}
+
+StartAndEndValidity::StartAndEndValidity(Time32 start, Time32 end) :
+    start_validity(start), end_validity(end) {}
+
+StartAndDurationValidity::StartAndDurationValidity(Time32 start, Duration dur) :
+    start_validity(start), duration(dur) {}
+
+ValidityRestrictionType get_type(const ValidityRestriction& restriction)
+{
+    struct validity_restriction_visitor : public boost::static_visitor<ValidityRestrictionType>
+    {
+        ValidityRestrictionType operator()(const EndValidity&)
+        {
+            return ValidityRestrictionType::Time_End;
+        }
+        ValidityRestrictionType operator()(const StartAndEndValidity&)
+        {
+            return ValidityRestrictionType::Time_Start_And_End;
+        }
+        ValidityRestrictionType operator()(const StartAndDurationValidity&)
+        {
+            return ValidityRestrictionType::Time_Start_And_Duration;
+        }
+        ValidityRestrictionType operator()(const GeographicRegion&)
+        {
+            return ValidityRestrictionType::Region;
+        }
+    };
+
+    validity_restriction_visitor visit;
+    return boost::apply_visitor(visit, restriction);
+}
+
+size_t get_size(const Time32&)
+{
+    return sizeof(Time32);
+}
+
+size_t get_size(const Time64&)
+{
+    return sizeof(Time64);
+}
+
+size_t get_size(const Duration&)
+{
+    return sizeof(uint16_t);
+}
+
+size_t get_size(const StartAndEndValidity& validity)
+{
+    size_t size = sizeof(validity.end_validity);
+    size += sizeof(validity.start_validity);
+    return size;
+}
+
+size_t get_size(const StartAndDurationValidity& validity)
+{
+    size_t size = sizeof(validity.start_validity);
+    size += get_size(validity.duration);
+    return size;
+}
+
+size_t get_size(const ValidityRestriction& restriction)
+{
+    size_t size = sizeof(ValidityRestrictionType);
+    struct validity_restriction_visitor : public boost::static_visitor<size_t>
+    {
+        size_t operator()(const EndValidity& validity)
+        {
+            return sizeof(validity);
+        }
+        size_t operator()(const StartAndEndValidity& validity)
+        {
+            return get_size(validity);
+        }
+        size_t operator()(const StartAndDurationValidity& validity)
+        {
+            return get_size(validity);
+        }
+        size_t operator()(const GeographicRegion& region)
+        {
+            return get_size(region);
+        }
+    };
+
+    validity_restriction_visitor visit;
+    size += boost::apply_visitor(visit, restriction);
+    return size;
+}
+
+size_t deserialize(InputArchive& ar, ValidityRestriction& restriction)
+{
+    size_t size = 0;
+    ValidityRestrictionType type;
+    deserialize(ar, type);
+    size += sizeof(ValidityRestrictionType);
+    switch (type) {
+        case ValidityRestrictionType::Time_End: {
+            EndValidity end;
+            deserialize(ar, end);
+            size += sizeof(end);
+            restriction = end;
+            break;
+        }
+        case ValidityRestrictionType::Time_Start_And_Duration: {
+            StartAndDurationValidity validity;
+            deserialize(ar, validity.start_validity);
+            uint16_t duration;
+            deserialize(ar, duration);
+            validity.duration = Duration(duration);
+            size += get_size(validity);
+            restriction = validity;
+            break;
+        }
+        case ValidityRestrictionType::Time_Start_And_End: {
+            StartAndEndValidity validity;
+            deserialize(ar, validity.start_validity);
+            deserialize(ar, validity.end_validity);
+            restriction = validity;
+            size += get_size(validity);
+            break;
+        }
+        case ValidityRestrictionType::Region: {
+            GeographicRegion region;
+            size += deserialize(ar, region);
+            restriction = region;
+            break;
+        }
+        default:
+            throw deserialization_error("Unknown ValidityRestrictionType");
+    }
+    return size;
+}
+
+void serialize(OutputArchive& ar, const ValidityRestriction& restriction)
+{
+    struct validity_restriction_visitor : public boost::static_visitor<>
+    {
+        validity_restriction_visitor(OutputArchive& ar) :
+            m_archive(ar)
+        {
+        }
+        void operator()(const EndValidity& validity)
+        {
+            serialize(m_archive, host_cast(validity));
+        }
+        void operator()(const StartAndEndValidity& validity)
+        {
+            serialize(m_archive, host_cast(validity.start_validity));
+            serialize(m_archive, host_cast(validity.end_validity));
+        }
+        void operator()(const StartAndDurationValidity& validity)
+        {
+            serialize(m_archive, host_cast(validity.start_validity));
+            serialize(m_archive, host_cast(validity.duration.raw()));
+        }
+        void operator()(const GeographicRegion& region)
+        {
+            serialize(m_archive, region);
+        }
+        OutputArchive& m_archive;
+    };
+
+    ValidityRestrictionType type = get_type(restriction);
+    serialize(ar, type);
+    validity_restriction_visitor visit(ar);
+    boost::apply_visitor(visit, restriction);
+}
+
+} // namespace v2
+} // namespace security
+} // namespace vanetza