Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/security/v2/header_field.hpp

@@ -0,0 +1,144 @@
+#ifndef HEADER_FIELD_HPP_IHIAKD4K
+#define HEADER_FIELD_HPP_IHIAKD4K
+
+#include <vanetza/security/v2/basic_elements.hpp>
+#include <vanetza/security/v2/certificate.hpp>
+#include <vanetza/security/v2/encryption_parameter.hpp>
+#include <vanetza/security/v2/int_x.hpp>
+#include <vanetza/security/v2/recipient_info.hpp>
+#include <vanetza/security/v2/region.hpp>
+#include <vanetza/security/v2/signer_info.hpp>
+#include <boost/variant/variant.hpp>
+#include <list>
+
+namespace vanetza
+{
+namespace security
+{
+namespace v2
+{
+
+/// HeaderFieldType specified in TS 103 097 v1.2.1, section 5.5
+enum class HeaderFieldType : uint8_t
+{
+    Generation_Time = 0,                    // Time64
+    Generation_Time_Confidence = 1,         // Time64WithStandardDeviation
+    Expiration = 2,                         // Time32
+    Generation_Location = 3,                // TreeDLocation
+    Request_Unrecognized_Certificate = 4,   // std::list<HashedId3>
+    Its_Aid = 5,                            // IntX
+    Signer_Info = 128,                      // SignerInfo
+    Encryption_Parameters = 129,            // EncryptionParameters
+    Recipient_Info = 130,                   // std::list<RecipientInfo>
+};
+
+/// HeaderField specified in TS 103 097 v1.2.1, section 5.4
+using HeaderField = boost::variant<
+    Time64,
+    Time64WithStandardDeviation,
+    Time32,
+    ThreeDLocation,
+    std::list<HashedId3>,
+    IntX,
+    SignerInfo,
+    EncryptionParameter,
+    std::list<RecipientInfo>
+>;
+
+/**
+ * \brief Determines HeaderFieldType to a given HeaderField
+ * \param field
+ * \return type
+ */
+HeaderFieldType get_type(const HeaderField& field);
+
+/**
+ * \brief Calculates size of a HeaderField
+ * \param field
+ * \return number of octets needed to serialize the HeaderField
+ */
+std::size_t get_size(const HeaderField& field);
+
+/**
+ * \brief Serializes a HeaderField into a binary archive
+ * \note Serialization of HeaderField lists is provided by template
+ * \param ar to serialize in
+ * \param field to serialize
+ */
+void serialize(OutputArchive& ar, const HeaderField& field);
+
+/**
+ * \brief Deserializes a list of HeaderFields from a binary archive
+ * \param ar with a serialized list of HeaderFields at the beginning
+ * \param list of HeaderFields to deserialize
+ * \return size of the deserialized list
+ */
+size_t deserialize(InputArchive& ar, std::list<HeaderField>& list);
+
+/**
+ * \brief resolve type for matching HeaderFieldType
+ *
+ * This is kind of the reverse function of get_type(const HeaderField&)
+ */
+template<HeaderFieldType>
+struct header_field_type;
+
+template<>
+struct header_field_type<HeaderFieldType::Generation_Time>
+{
+    using type = Time64;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Generation_Time_Confidence>
+{
+    using type = Time64WithStandardDeviation;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Expiration>
+{
+    using type = Time32;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Generation_Location>
+{
+    using type = ThreeDLocation;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Request_Unrecognized_Certificate>
+{
+    using type = std::list<HashedId3>;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Its_Aid>
+{
+    using type = IntX;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Signer_Info>
+{
+    using type = SignerInfo;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Encryption_Parameters>
+{
+    using type = EncryptionParameter;
+};
+
+template<>
+struct header_field_type<HeaderFieldType::Recipient_Info>
+{
+    using type = std::list<RecipientInfo>;
+};
+
+} // namespace v2
+} // namespace security
+} // namespace vanetza
+
+#endif /* HEADER_FIELD_HPP_IHIAKD4K */