packet

Documentation

Index

• Constants
• Variables
• func CheckUnixEpochTimestamp(b []byte) error
• type Client
  • func NewClient(psk []byte) (*Client, error)
  • func (c *Client) ParseResponse(resp []byte) (netip.AddrPort, error)
  • func (c *Client) PutRequest(req []byte)
• type Server
  • func NewServer(psk []byte) (*Server, error)
  • func (s *Server) Handle(clientAddrPort netip.AddrPort, req []byte, resp []byte) error

Constants

const (
	MessageTypeRequest = iota
	MessageTypeResponse
)

const (
	// random nonce + unix epoch timestamp + type + AEAD tag
	RequestPacketSize = chacha20poly1305.NonceSizeX + 8 + 1 + chacha20poly1305.Overhead

	// random nonce + unix epoch timestamp + type + IP + port + AEAD tag
	ResponsePacketSize = chacha20poly1305.NonceSizeX + 8 + 1 + 16 + 2 + chacha20poly1305.Overhead
)

const (
	// MaxEpochDiff is the maximum allowed time difference between a received timestamp and system time.
	MaxEpochDiff = 30

	// MaxTimeDiff is the maximum allowed time difference between a received timestamp and system time.
	MaxTimeDiff = MaxEpochDiff * time.Second

	// ReplayWindowDuration defines the amount of time during which a nonce check is necessary.
	ReplayWindowDuration = MaxTimeDiff * 2
)

Variables

var (
	ErrBadPacketSize  = errors.New("bad packet size")
	ErrRepeatedNonce  = errors.New("repeated nonce")
	ErrBadTimestamp   = errors.New("time offset too large")
	ErrBadMessageType = errors.New("bad message type")
)

Functions

func CheckUnixEpochTimestamp

func CheckUnixEpochTimestamp(b []byte) error

CheckUnixEpochTimestamp checks the Unix Epoch timestamp in the buffer and returns an error if the timestamp exceeds the allowed time difference from system time.

This function does not check buffer length. Make sure it's at least 8 bytes long.

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client generates request packets and parses response packets.

func NewClient

func NewClient(psk []byte) (*Client, error)

NewClient creates a new client with the given PSK.

func (*Client) ParseResponse

func (c *Client) ParseResponse(resp []byte) (netip.AddrPort, error)

ParseResponse parses the response packet and returns the client IP and port.

func (*Client) PutRequest

func (c *Client) PutRequest(req []byte)

PutRequest writes a request packet to the first RequestPacketSize bytes of the given buffer.

type Server

type Server struct {
	// contains filtered or unexported fields
}

Server generates responses to request packets.

func NewServer

func NewServer(psk []byte) (*Server, error)

NewServer creates a new server with the given PSK.

func (*Server) Handle

func (s *Server) Handle(clientAddrPort netip.AddrPort, req []byte, resp []byte) error

Handle processes the request packet and writes the response packet to the first ResponsePacketSize bytes of the given buffer.