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/v3/sign_header_policy.hpp

@@ -0,0 +1,96 @@
+#pragma once
+#include <vanetza/common/clock.hpp>
+#include <vanetza/common/runtime.hpp>
+#include <vanetza/security/hashed_id.hpp>
+#include <vanetza/security/peer_request_tracker.hpp>
+#include <boost/optional/optional.hpp>
+
+namespace vanetza
+{
+
+// forward declaration
+class PositionProvider;
+
+namespace security
+{
+
+// forward declarations
+class CertificateProvider;
+struct SignRequest;
+
+namespace v3
+{
+
+
+/**
+ * SignHeaderPolicy is used while signing messages
+ *
+ * SignHeaderPolicy determines the header fields to be included in the secured message.
+ * Other components can influence the policy's behaviour by calling one of its "report" methods.
+ */
+class SignHeaderPolicy
+{
+public:
+    /**
+     * Prepare header fields for next secured message.
+     *
+     * \param req signing request (including ITS-AID for example)
+     * \param secured_message output message
+     * \return header fields
+     */
+    virtual void prepare_header(const SignRequest& req, SecuredMessage& secured_message) = 0;
+
+    /**
+     * Mark certificate as unrecognized in next secured message
+     * \param id hash of unknown certificate
+     */
+    virtual void request_unrecognized_certificate(HashedId8 id) = 0;
+
+    /**
+     * Request a full certificate to be included in next secured message
+     */
+    virtual void request_certificate() = 0;
+
+    /**
+     * Enqueue a certificate for P2P distribution.
+     * \param id hash of requested certificate
+     */
+    virtual void enqueue_p2p_request(HashedId3 id) = 0;
+
+    /**
+     * Discard a P2P certificate request.
+     * \param id hash of requested certificate
+     */
+    virtual void discard_p2p_request(HashedId3 id) = 0;
+
+    virtual ~SignHeaderPolicy() = default;
+};
+
+/**
+ * DefaultSignHeaderPolicy implements the default behaviour specified by ETSI TS 103 097 V2.1.1
+ */
+class DefaultSignHeaderPolicy : public SignHeaderPolicy
+{
+public:
+    DefaultSignHeaderPolicy(const Runtime&, PositionProvider& positioning, CertificateProvider&);
+
+    void prepare_header(const SignRequest& request, SecuredMessage& secured_message) override;
+    void request_unrecognized_certificate(HashedId8 id) override;
+    void request_certificate() override;
+    void enqueue_p2p_request(HashedId3) override;
+    void discard_p2p_request(HashedId3) override;
+
+private:
+    const Runtime& m_runtime;
+    PositionProvider& m_positioning;
+    CertificateProvider& m_cert_provider;
+    Clock::time_point m_cam_next_certificate;
+    bool m_cert_requested;
+    PeerRequestTracker m_incoming_requests;
+    PeerRequestTracker m_outgoing_requests;
+};
+
+} // namespace v3
+} // namespace security
+} // namespace vanetza
+