tcpoverdns

type Flag uint16

type InitiatorConfig struct {
	// SetConfig instructs the responder to configure itself according to the
	// parameters specified here.
	SetConfig bool
	// MaxSegmentLenExclHeader is the maximum length of the data portion in an
	// outgoing segment, the length excludes the headers.
	MaxSegmentLenExclHeader int
	// Debug enables verbose logging for IO activities.
	Debug bool
	// Timing configures the transmission control's timing
	// characteristics.
	Timing TimingConfig
}

type Segment struct {
	// Flags is a bitmap of individual control bits that help the stream to
	// transition between its states.
	Flags Flag
	// ID is the ID of the transmission control that constructed this segment.
	ID uint16
	// SeqNum is the sequence number of the first byte of data of the segment.
	SeqNum uint32
	// AckNum differs from the way it works in TCP. Over here it is the sequence
	// number of the latest byte arrived, whereas in TCP it is the next sequence
	// number expected from peer - oops!
	AckNum uint32
	// Reserved is a two-byte integer. It is currently used to inject a small
	// amount of randomness into the segment.
	Reserved uint16
	Data     []byte
}

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

type State int

type TimingConfig struct {
	// SlidingWindowWaitDuration is a short duration to wait the peer's
	// acknowledgement before this transmission control sends more data to the
	// output transport, including during consecutive retransmissions.
	// In practice, the duration should be higher than the initial
	// KeepAliveInterval.
	SlidingWindowWaitDuration time.Duration
	// RetransmissionInterval is a short duration to wait before re-transmitting
	// the unacknowledged outbound segments (if any). Subsequent retransmissions
	// occur at the interval of SlidingWindowWaitDuration.
	RetransmissionInterval time.Duration
	// AckDelay is a short delay between receiving the latest segment and
	// sending an outbound acknowledgement-only segment.
	// It should shorter than the retransmission interval by a magnitude.
	AckDelay time.Duration
	// KeepAliveInterval is a short duration to wait before transmitting an
	// outbound ack segment in the absence of outbound data.
	// This internal must be longer than the peer's retransmission interval.
	KeepAliveInterval time.Duration
	// ReadTimeout specifies a time limit for the Read function.
	ReadTimeout time.Duration
	// WriteTimeout specifies a time limit for the Write function.
	WriteTimeout time.Duration
}

type TransmissionControl struct {
	net.Conn
	// ID is a file descriptor-like number that identifies all outgoing segments
	// as well as used for logging.
	ID uint16
	// Debug enables verbose logging for IO activities.
	Debug bool
	// Logger is used to log IO activities when verbose logging is enabled.
	Logger *lalog.Logger
	// LogTag is a string that shows up in all log entries.
	LogTag string

	// Initiator determines whether this transmission control will initiate
	// the handshake sequence with the peer.
	// Otherwise, this transmission control remains passive at the start.
	Initiator bool
	// InitiatorConfig is an optional set of configuration parameters that this
	// transmission control will invite the peer to use.
	InitiatorConfig InitiatorConfig
	// InitiatorSegmentData is an optional byte array carried by initiator's
	// handshake (SYN) segment. It must be shorter than MaxSegmentLenExclHeader
	// minus InitiatorConfigLen.
	InitiatorSegmentData []byte
	// InitialTiming has the initial timing characteristics of this transmission
	// control without runtime adjustments.
	InitialTiming TimingConfig
	// InitialTiming has the live timing characteristics of this transmission
	// control including runtime adjustments.
	LiveTiming TimingConfig

	// MaxSegmentLenExclHeader is the maximum length of the data portion in an
	// outgoing segment, the length excludes the headers.
	MaxSegmentLenExclHeader int
	// InputTransport transports inbound segments.
	InputTransport io.Reader
	// OutputTransport transports outbound segments.
	OutputTransport io.Writer
	// OutputSegmentCallback (optional) is invoked for each outbound segment as
	// they are written to output transport.
	OutputSegmentCallback func(Segment)
	// PostHandshakeCallback (optional) is invoked immediately after the
	// initiator config is applied in this transmission control.
	PostConfigCallback func()

	// MaxSlidingWindow is the maximum length of data buffered in the outgoing
	// direction without receiving acknowledge from the peer.
	// This number is comparable to the TCP flow control sliding window.
	MaxSlidingWindow uint32
	// MaxRetransmissions is the maximum number of retransmissions that can be
	// made for handshake and data segments before the transmission control is
	// irreversably closed.
	MaxRetransmissions int
	// MaxTransportErrors is the maximum number of consecutive errors to
	// tolerate from input and output transports before closing down the
	// transmission control.
	MaxTransportErrors int
	// MaxLifetime is the maximum lifetime of the transmission control. After
	// the lifetime elapses, the transmission control will be unconditionally
	// closed/terminated.
	// This is used as a safeguard against transmission control going stale
	// without being properly closed/terminated.
	MaxLifetime time.Duration
	// contains filtered or unexported fields
}