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/cam_ssp.hpp

@@ -0,0 +1,92 @@
+#ifndef CAM_SSP_HPP_GGBE8KES
+#define CAM_SSP_HPP_GGBE8KES
+
+#include <vanetza/common/byte_buffer.hpp>
+#include <cstdint>
+#include <set>
+#include <string>
+
+namespace vanetza
+{
+namespace security
+{
+
+/**
+ * CAM permission bits
+ *
+ * These bitmasks describe CA station roles, e.g. emergency vehicles.
+ * Some CAM data containers are linked to these roles. Misuse is opposed by checking CAM SSPs.
+ *
+ * \see EN 302 637-2 V1.3.2, Table 4
+ */
+enum class CamPermission : uint16_t
+{
+    // first octet
+    CEN_DSRC_Tolling_Zone = 0x80,
+    Public_Transport = 0x40,
+    Special_Transport = 0x20,
+    Dangerous_Goods = 0x10,
+    Roadwork = 0x08,
+    Rescue = 0x04,
+    Emergency = 0x02,
+    Safety_Car = 0x01,
+
+    // second octet
+    Closed_Lanes = 0x8000,
+    Request_For_Right_Of_Way = 0x4000,
+    Request_For_Free_Crossing_At_Traffic_Light = 0x2000,
+    No_Passing = 0x1000,
+    No_Passing_For_Trucks = 0x0800,
+    Speed_Limit = 0x0400,
+    // 0x0200 and 0x0100 are reserved for future usage
+};
+
+/**
+ * Set of CAM permissions, i.e. Service Specific Permissions
+ *
+ * \see EN 302 637-2 V1.3.2, section 6.2.2.2
+ */
+class CamPermissions
+{
+public:
+    CamPermissions();
+    CamPermissions(CamPermission);
+    CamPermissions(const std::initializer_list<CamPermission>&);
+
+    // check for permission
+    bool has(CamPermission) const;
+    bool has(const std::initializer_list<CamPermission>&) const;
+    bool has(const CamPermissions&) const;
+    bool none() const;
+
+    /**
+     * Get set of all included permissions
+     * \return permission set
+     */
+    std::set<CamPermission> permissions() const;
+
+    // permission manipulation (with chaining)
+    CamPermissions& add(CamPermission);
+    CamPermissions& remove(CamPermission);
+
+    // serialization helpers
+    ByteBuffer encode() const;
+    static CamPermissions decode(const ByteBuffer&);
+
+private:
+    using value_type = std::underlying_type<CamPermission>::type;
+    value_type m_bits;
+};
+
+/**
+ * Get string representation of CAM permission flag
+ * \param cp CAM permission flag
+ * \return string representation (empty for unknown flags)
+ */
+std::string stringify(CamPermission);
+
+} // namespace security
+} // namespace vanetza
+
+#endif /* CAM_SSP_HPP_GGBE8KES */
+