kcenon::network::protocols::quic::packet_number Class Reference

QUIC packet number utilities (RFC 9000 Section 17.1) More...

#include <packet.h>

Collaboration diagram for kcenon::network::protocols::quic::packet_number:

Static Public Member Functions
static auto	encode (uint64_t full_pn, uint64_t largest_acked) -> std::pair< std::vector< uint8_t >, size_t >
	Encode a packet number for transmission.
static auto	decode (uint64_t truncated_pn, size_t pn_length, uint64_t largest_pn) noexcept -> uint64_t
	Decode a packet number from received data.
static auto	encoded_length (uint64_t full_pn, uint64_t largest_acked) noexcept -> size_t
	Get the minimum number of bytes needed to encode a packet number.

Detailed Description

QUIC packet number utilities (RFC 9000 Section 17.1)

Packet numbers are encoded using a variable-length encoding based on the difference from the largest acknowledged packet number.

Definition at line 173 of file packet.h.

Member Function Documentation

decode()

auto kcenon::network::protocols::quic::packet_number::decode ( uint64_t truncated_pn, size_t pn_length, uint64_t largest_pn ) -> uint64_t

staticnodiscardnoexcept

Decode a packet number from received data.

Parameters

truncated_pn	Truncated packet number from packet
pn_length	Length of the truncated packet number (1-4)
largest_pn	Largest packet number received so far

Returns

Full recovered packet number

Definition at line 103 of file packet.cpp.

{
    // RFC 9000 Appendix A
    uint64_t expected_pn = largest_pn + 1;
    uint64_t pn_win = 1ULL << (pn_length * 8);
    uint64_t pn_hwin = pn_win / 2;
    uint64_t pn_mask = pn_win - 1;
 
    // Reconstruct the full packet number
    uint64_t candidate_pn = (expected_pn & ~pn_mask) | truncated_pn;
 
    // Handle wrap-around cases
    if (candidate_pn <= expected_pn - pn_hwin && candidate_pn < (1ULL << 62) - pn_win)
    {
        return candidate_pn + pn_win;
    }
    if (candidate_pn > expected_pn + pn_hwin && candidate_pn >= pn_win)
    {
        return candidate_pn - pn_win;
    }
    return candidate_pn;
}

Referenced by kcenon::network::internal::quic_socket::handle_packet().

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encode()

auto kcenon::network::protocols::quic::packet_number::encode ( uint64_t full_pn, uint64_t largest_acked ) -> std::pair<std::vector<uint8_t>, size_t>

staticnodiscard

Encode a packet number for transmission.

Parameters

full_pn	Full packet number to encode
largest_acked	Largest acknowledged packet number (0 if none)

Returns

Pair of (encoded bytes, number of bytes used)

Definition at line 88 of file packet.cpp.

{
    size_t len = encoded_length(full_pn, largest_acked);
    std::vector<uint8_t> result(len);
 
    // Encode in big-endian order
    for (size_t i = 0; i < len; ++i)
    {
        result[len - 1 - i] = static_cast<uint8_t>(full_pn >> (i * 8));
    }
 
    return {result, len};
}

Referenced by kcenon::network::protocols::quic::packet_builder::build_handshake(), kcenon::network::protocols::quic::packet_builder::build_initial(), kcenon::network::protocols::quic::packet_builder::build_short(), and kcenon::network::protocols::quic::packet_builder::build_zero_rtt().

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encoded_length()

auto kcenon::network::protocols::quic::packet_number::encoded_length ( uint64_t full_pn, uint64_t largest_acked ) -> size_t

staticnodiscardnoexcept

Get the minimum number of bytes needed to encode a packet number.

Parameters

full_pn	Full packet number
largest_acked	Largest acknowledged packet number

Returns

Number of bytes (1-4)

Definition at line 127 of file packet.cpp.

{
    uint64_t num_unacked = (full_pn > largest_acked) ? (full_pn - largest_acked) : 1;
 
    if (num_unacked < (1ULL << 7))
    {
        return 1;
    }
    if (num_unacked < (1ULL << 15))
    {
        return 2;
    }
    if (num_unacked < (1ULL << 23))
    {
        return 3;
    }
    return 4;
}

Referenced by kcenon::network::protocols::quic::packet_builder::build_handshake(), kcenon::network::protocols::quic::packet_builder::build_initial(), kcenon::network::protocols::quic::packet_builder::build_short(), and kcenon::network::protocols::quic::packet_builder::build_zero_rtt().

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The documentation for this class was generated from the following files:

• src/internal/protocols/quic/packet.h
• src/protocols/quic/packet.cpp