VBVX - VPP Buffer View eXtensions

VBVX (VPP Buffer View eXtensions) is a small, header-only C++23 library for zero-copy parsing of packet buffers. It provides views over common on-wire headers (Ethernet, VLAN, ARP, IPv4/v6, TCP/UDP, ICMP, SRv6) without copying.

About

• Purpose: Safe, zero-copy access to common wire-protocol headers for packet parsing/inspection.
• Core abstractions:
  • BufferView - parses offsets and exposes header views and helper accessors (e.g., ether_type(), l3_offset(), l4_offset()).
  • HeaderView<H> - lightweight wrapper around const H* with a .copy() helper when a local value is needed.
  • FlagsView / ConstFlagsView - zero-copy, chainable views for bitmask enums; enable operators by specializing vbvx::enable_bitmask_operators<YourEnum>.
  • vbvx/* - packed POD header structs with compile-time checks for layout and alignment.

Design notes: headers are [[gnu::packed]] with alignof == 1. On-wire fields are network byte order; use helpers like autoswap to convert to host order.

Features

• Zero-copy, bounds-checked views for L2/L3/L4 headers (Ethernet/VLAN/ARP, IPv4/IPv6, TCP/UDP, ICMP)
• SRv6 (Segment Routing over IPv6): SRH segment list + TLV parsing
• Header-only C++23 library (easy to vendor)
• Endianness agnostic (e.g., autoswap) and sane accessors for on-wire fields
• GoogleTest-based unit tests that cover parsing branches

Using VBVX from CMake

You can consume VBVX from your CMake-based project in two common ways: vendoring it with add_subdirectory, or fetching it at configure time with FetchContent.

1) Via add_subdirectory (vendored or submodule)

Add the VBVX source tree into your project (e.g., as a submodule or copied directory) and call:

# From your top-level CMakeLists.txt
add_subdirectory(path/to/vbvx)

# Link the provided target into your executable/library
target_link_libraries(my_app PRIVATE vbvx::vbvx)

This is simple and keeps control in your project's tree.

2) Via FetchContent (recommended for external deps)

Use CMake's FetchContent to declare and make VBVX available at configure time. Pin a tag or commit for reproducible builds:

include(FetchContent)

FetchContent_Declare(vbvx
  GIT_REPOSITORY https://github.com/llmxio/vbvx.git
  GIT_TAG        vX.Y.Z  # pin to a release tag or commit
)
FetchContent_MakeAvailable(vbvx)

target_link_libraries(my_app PRIVATE vbvx::vbvx)

Notes:

• Prefer pinning a tag or commit with FetchContent for reproducible builds.
• If you installed (see below) VBVX system-wide via cmake --install, you can also use find_package(VBVX CONFIG REQUIRED) and link vbvx::vbvx.

Install

Requirements:

• A C++23-capable compiler (GCC/Clang) and CMake (Ninja recommended).

Quick build and test:

# Configure (enable tests)
cmake -G Ninja -B build -S . -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTING=ON
# Build
cmake --build build
# Run tests (verbose)
ctest --test-dir build -V
# Or run a specific test binary
build/tests/vbvx_tests --gtest_filter=TestSuite.TestName

Optional install:

cmake --install build --prefix /some/install/prefix

Documentation

Build the HTML API docs using Doxygen (requires Doxygen to be installed):

# Configure with docs enabled
cmake -S . -B build -DBUILD_DOCS=ON
# Build docs target
cmake --build build --target docs
# HTML output: build/docs/html

Usage

Include the main header and construct a BufferView over your packet data:

#include "vbvx/buffer_view.hxx"

vbvx::BufferView buf(data, len);
if (auto ip = buf.ipv4_header()) {
  if (auto proto = buf.ip_protocol(); proto == vbvx::IpProtocol::TCP) {
    if (auto tcp = buf.tcp_header()) {
      auto src_port = tcp->src_port();
      auto dst_port = tcp->dst_port();
      // use src/dst
    }
  }
}

Notes:

• Use hv.copy() on a HeaderView when you need a local copy to mutate or hold beyond the original buffer lifetime.
• Expect on-wire fields in network byte order; use autoswap or provided helpers to get host-order values.

SRv6

• SRv6 header definitions live in vbvx/srv6_header.hxx.
• Tests: tests/test_srv6_header.cxx, tests/test_srv6_tlv.cxx.
• Example - obtain an SRv6 header and inspect segments/TLVs:

#include "vbvx/buffer_view.hxx"

vbvx::BufferView buf(packet_data, packet_len);
if (auto srh = buf.srv6_header()) {
  if (!srh->is_valid_routing_type()) {
    // Not an SRH (routing type mismatch)
  } else {
    // Number of 128-bit SIDs in the segment list
    auto n = srh->segments_count();

    // Access the first SID (returns std::span<const uint8_t, 16>)
    auto first_sid = srh->segment_at(0);

    // Iterate TLVs without allocation
    vbvx::SRv6TlvIterator it(srh->tlv_first_ptr(), srh->tlv_bytes_len());
    vbvx::SRv6Tlv t;
    while (it.next(t)) {
      // handle t.type, t.length and t.value
    }
  }
}

• Note: BufferView::srv6_header() returns an SRH only when the IPv6 Next Header is Routing (43) and the SRH is the first extension header.
• When adding SRv6 features/tests, follow the existing pattern: raw byte arrays in wire order + HeaderView/BufferView assertions.

FlagsView

Use this when you’ve got a bitmask enum (usually a field inside a header struct) and you want a small view to flip bits without copying.

• FlagsView<Enum>: mutable, chainable (set/clear/toggle/reset)
• ConstFlagsView<Enum>: read-only (has/has_all)
• To enable |, &, ^, ~, and shifts on your enum, specialize vbvx::enable_bitmask_operators<Enum> to std::true_type

Example:

#include "vbvx/flags_view.hxx"

enum class FooFlags : uint8_t {
  None = 0,
  A = 1 << 0,
  B = 1 << 1,
  C = 1 << 2,
};

template<> struct vbvx::enable_bitmask_operators<FooFlags> : std::true_type {};

FooFlags flags = FooFlags::None;

vbvx::FlagsView fv(flags);
fv.set(FooFlags::A).set(FooFlags::B);
fv.clear(FooFlags::A);
fv.toggle(FooFlags::C);

if (fv.has(FooFlags::B)) {
  // ...
}

vbvx::ConstFlagsView cfv = fv;
auto current = cfv.value();

Notes: No allocation, no indirection: it just operates on the underlying enum value you pass in.

License & Acknowledgements

Full terms are in the LICENSE file.