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FLASHING.md says how to take a newer version of the colleague's tree (copy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/geonet/cbf_packet_buffer.hpp

@@ -0,0 +1,202 @@
+#ifndef CBF_PACKET_BUFFER_HPP_MU3RK5V1
+#define CBF_PACKET_BUFFER_HPP_MU3RK5V1
+
+#include <vanetza/common/clock.hpp>
+#include <vanetza/geonet/cbf_packet_identifier.hpp>
+#include <vanetza/geonet/packet.hpp>
+#include <vanetza/geonet/pending_packet.hpp>
+#include <vanetza/geonet/pdu_variant.hpp>
+#include <boost/bimap/bimap.hpp>
+#include <boost/bimap/multiset_of.hpp>
+#include <boost/bimap/unordered_set_of.hpp>
+#include <boost/optional/optional.hpp>
+#include <cstddef>
+#include <list>
+#include <memory>
+
+// forward declarations
+namespace vanetza
+{
+class Runtime;
+
+namespace geonet
+{
+class Address;
+class CbfCounter;
+class CbfPacket;
+class Lifetime;
+
+/**
+ * CbfPacket enables handling of conventional packets in a CBF packet buffer.
+ * It contains a GeoBroadcast PDU and the network layer payload.
+ */
+class CbfPacket
+{
+public:
+    CbfPacket(PendingPacket<GbcPdu>&&, const MacAddress& sender);
+    CbfPacket(PendingPacket<GbcPdu, const MacAddress&>&&, const MacAddress& sender);
+
+    CbfPacket(CbfPacket&&) = default;
+    CbfPacket& operator=(CbfPacket&&) = default;
+
+    /**
+     * Get sender of buffered packet
+     * \return sender's link-layer address
+     */
+    const MacAddress& sender() const;
+
+    /**
+     * Get source address of buffered packet
+     * \return source address
+     */
+    const Address& source() const;
+
+    /**
+     * Get sequence number of buffered packet
+     * \return sequence number
+     */
+    SequenceNumber sequence_number() const;
+
+    /**
+     * Reduce lifetime of buffered packet
+     * \param d reduce lifetime by this duration
+     * \return remaining lifetime
+     */
+    Clock::duration reduce_lifetime(Clock::duration d);
+
+    /**
+     * Length of packet data in bytes (PDU including payload)
+     * \return size of packet on wire
+     */
+    std::size_t length() const;
+
+    PendingPacket<GbcPdu> packet() && { return std::move(m_packet); }
+
+private:
+    PendingPacket<GbcPdu> m_packet;
+    MacAddress m_sender;
+};
+
+
+/**
+ * CbfPacketBuffer facilitates implementation of contention based forwarding
+ */
+class CbfPacketBuffer
+{
+public:
+    using TimerCallback = std::function<void(PendingPacket<GbcPdu>&&)>;
+    using Identifier = CbfPacketIdentifier;
+
+    /**
+     * Create CBF packet buffer with bounded capacity
+     * \param rt Runtime instance used for internal timers
+     * \param cb Callback invoked for each packet on expiry
+     * \param cnt CBF counter implementation
+     * \param bytes Buffer can hold at most this number of bytes
+     */
+    CbfPacketBuffer(Runtime& rt, TimerCallback cb, std::unique_ptr<CbfCounter> cnt, std::size_t bytes);
+    ~CbfPacketBuffer();
+
+    /**
+     * Enqueue a packet and start an associated timer expiring after timeout
+     * \param packet Buffer this packet
+     * \param timeout CBF timer expiration for this packet
+     */
+    void add(CbfPacket&& packet, Clock::duration timeout);
+
+    /**
+     * Try to remove a packet from buffer.
+     * \param id packet identification
+     * \return true if packet existed before removal
+     */
+    bool remove(const Identifier& id);
+
+    /**
+     * Update associated packet timer
+     * \param id packet identification
+     * \param timeout CBF timer expiration
+     */
+    void update(const Identifier& id, Clock::duration timeout);
+
+    /**
+     * Fetch a packet from buffer.
+     *
+     * Associated timer is automatically stopped and packet removed from buffer.
+     * Packet lifetime is reduced by queueing time at return.
+     *
+     * \param id packet identification
+     * \return packet if found in buffer
+     */
+    boost::optional<CbfPacket> fetch(const Identifier& id);
+
+    /**
+     * Find packet in buffer.
+     * \param id packet identification
+     * \return read-only pointer to packet, nullptr if not found
+     */
+    const CbfPacket* find(const Identifier& id) const;
+
+    /**
+     * Get counter associated with given packet
+     * \note packet counter is incremented at each timer update
+     * \param id packet identification
+     * \return 0 if packet has never been buffered before
+     */
+    std::size_t counter(const Identifier& packet) const;
+
+private:
+
+    struct Timer
+    {
+        Timer(const Runtime&, Clock::duration timeout);
+        Timer(const Timer&) = default;
+        Timer& operator=(const Timer&) = default;
+        bool operator<(const Timer&) const;
+
+        Clock::time_point expiry;
+        Clock::time_point start;
+    };
+
+    using timer_bimap = boost::bimaps::bimap<
+        boost::bimaps::multiset_of<Timer>,
+        boost::bimaps::unordered_set_of<Identifier, std::hash<Identifier>>,
+        boost::bimaps::with_info<std::list<CbfPacket>::iterator>
+    >;
+
+    /**
+     * Flush all expired packets
+     */
+    void flush();
+
+    /**
+     * Remove timer from map and reschedule timer event if necessary
+     */
+    void remove_timer(typename timer_bimap::left_map::iterator);
+
+    /**
+     * Schedule next timer event at runtime
+     */
+    void schedule_timer();
+
+    /**
+     * Reduce packet lifetime by queueing time
+     * \param timer contains queueing start time
+     * \param packet associated packet
+     * \return true if packet remains valid, false if end of lifetime is reached
+     */
+    bool reduce_lifetime(const Timer&, CbfPacket&) const;
+
+    std::list<CbfPacket> m_packets;
+    timer_bimap m_timers;
+    Runtime& m_runtime;
+    std::unique_ptr<CbfCounter> m_counter;
+    const std::size_t m_capacity_bytes;
+    std::size_t m_stored_bytes;
+    TimerCallback m_timer_callback;
+};
+
+} // namespace geonet
+} // namespace vanetza
+
+#endif /* CBF_PACKET_BUFFER_HPP_MU3RK5V1 */
+