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/btp/header.cpp

@@ -0,0 +1,109 @@
+#include "header.hpp"
+#include <vanetza/common/serialization.hpp>
+#include <vanetza/common/serialization_buffer.hpp>
+
+namespace vanetza
+{
+namespace btp
+{
+
+using vanetza::serialize;
+using vanetza::deserialize;
+
+constexpr std::size_t HeaderA::length_bytes;
+constexpr std::size_t HeaderB::length_bytes;
+
+void serialize(OutputArchive& ar, const HeaderA& hdr)
+{
+    serialize(ar, hdr.destination_port);
+    serialize(ar, hdr.source_port);
+}
+
+void deserialize(InputArchive& ar, HeaderA& hdr)
+{
+    deserialize(ar, hdr.destination_port);
+    deserialize(ar, hdr.source_port);
+}
+
+void serialize(OutputArchive& ar, const HeaderB& hdr)
+{
+    serialize(ar, hdr.destination_port);
+    serialize(ar, hdr.destination_port_info);
+}
+
+void deserialize(InputArchive& ar, HeaderB& hdr)
+{
+    deserialize(ar, hdr.destination_port);
+    deserialize(ar, hdr.destination_port_info);
+}
+
+HeaderA parse_btp_a(CohesivePacket& packet)
+{
+    HeaderA hdr;
+    deserialize_from_range(hdr, packet[OsiLayer::Transport]);
+    packet.set_boundary(OsiLayer::Transport, btp::HeaderA::length_bytes);
+    return hdr;
+}
+
+HeaderA parse_btp_a(ChunkPacket& packet)
+{
+    HeaderA hdr;
+    ByteBuffer tmp;
+    packet[OsiLayer::Transport].convert(tmp);
+    deserialize_from_buffer(hdr, tmp);
+    return hdr;
+}
+
+HeaderA parse_btp_a(PacketVariant& packet)
+{
+    struct parse_btp_visitor : public boost::static_visitor<HeaderA>
+    {
+        HeaderA operator()(CohesivePacket& packet) {
+            return parse_btp_a(packet);
+        }
+
+        HeaderA operator()(ChunkPacket& packet) {
+            return parse_btp_a(packet);
+        }
+    };
+
+    parse_btp_visitor visitor;
+    return boost::apply_visitor(visitor, packet);
+}
+
+HeaderB parse_btp_b(CohesivePacket& packet)
+{
+    HeaderB hdr;
+    deserialize_from_range(hdr, packet[OsiLayer::Transport]);
+    packet.set_boundary(OsiLayer::Transport, btp::HeaderB::length_bytes);
+    return hdr;
+}
+
+HeaderB parse_btp_b(ChunkPacket& packet)
+{
+    HeaderB hdr;
+    ByteBuffer tmp;
+    packet[OsiLayer::Transport].convert(tmp);
+    deserialize_from_buffer(hdr, tmp);
+    return hdr;
+}
+
+HeaderB parse_btp_b(PacketVariant& packet)
+{
+    struct parse_btp_visitor : public boost::static_visitor<HeaderB>
+    {
+        HeaderB operator()(CohesivePacket& packet) {
+            return parse_btp_b(packet);
+        }
+
+        HeaderB operator()(ChunkPacket& packet) {
+            return parse_btp_b(packet);
+        }
+    };
+
+    parse_btp_visitor visitor;
+    return boost::apply_visitor(visitor, packet);
+}
+
+} // namespace btp
+} // namespace vanetza