PacketHeader.hpp File Reference

Wire format helpers for the UDP-first transport layer. More...

#include <SDL3/SDL_stdinc.h>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <vector>

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Classes
struct	net::PacketHeader
	36-byte header at the start of every UDP datagram. More...

Namespaces
namespace	net

Enumerations
enum class	net::PacketKind : std::uint8_t {   net::Payload = 0 , net::ConnectionRequest = 1 , net::ConnectionAccepted = 2 , net::Disconnect = 3 ,   net::KeepAlive = 4 , net::RelayPayload = 5 , net::DirectoryControl = 6 }
	Packet kind discriminator (PacketHeader::kind field). More...
enum class	net::ChannelId : std::uint8_t {   net::InputUnreliable = 0 , net::SnapshotUnreliableSequenced = 1 , net::ControlReliableOrdered = 2 , net::EventReliableOrdered = 3 ,   net::VoiceUnreliableSequenced = 4 , net::Count = 5 , net::Unreliable = InputUnreliable , net::UnreliableSequenced = SnapshotUnreliableSequenced ,   net::ReliableOrdered = EventReliableOrdered , net::ReliableUnordered = ControlReliableOrdered }
	Per-channel reliability + ordering semantics. More...

Functions
void	net::writeU16Le (std::uint8_t *out, std::uint16_t v)
void	net::writeU32Le (std::uint8_t *out, std::uint32_t v)
void	net::writeU64Le (std::uint8_t *out, std::uint64_t v)
std::uint16_t	net::readU16Le (const std::uint8_t *in)
std::uint32_t	net::readU32Le (const std::uint8_t *in)
std::uint64_t	net::readU64Le (const std::uint8_t *in)
void	net::encodePacketHeader (const PacketHeader &hdr, std::uint8_t *out)
bool	net::decodePacketHeader (const std::uint8_t *data, std::size_t len, PacketHeader &out)
std::vector< std::uint8_t >	net::makeDatagram (PacketHeader hdr, const void *payload, int payloadLen)

Variables
constexpr std::uint16_t	net::k_protocolMagic = 0x3247
	Magic bytes identifying our protocol. ASCII "G2" little-endian.
constexpr std::uint8_t	net::k_protocolVersion = 2
	Wire-format version. Bump on any incompatible layout change.
constexpr int	net::k_maxPacketBytes = 1200
	Maximum total UDP datagram bytes we intentionally emit.
constexpr std::uint8_t	net::k_flagFragmented = 0x01
constexpr std::uint8_t	net::k_flagEncrypted = 0x02
constexpr std::uint8_t	net::k_flagRelayPreferred = 0x04
constexpr int	net::k_maxPayloadBytes = k_maxPacketBytes - static_cast<int>(sizeof(PacketHeader))
	Maximum payload bytes a single non-fragmented datagram can carry.

Detailed Description

Wire format helpers for the UDP-first transport layer.

Protocol v2 puts session identity, route selection, channel sequence, selective ack state, and fragmentation metadata in every UDP datagram. The wire format is explicitly little-endian so future Steam / relay backends can share the same payload contract without relying on host endianness.