path

type HopField struct {
	// IngressRouterAlert flag. If the IngressRouterAlert is set, the ingress router (in
	// construction direction) will process the L4 payload in the packet.
	IngressRouterAlert bool
	// EgressRouterAlert flag. If the EgressRouterAlert is set, the egress router (in
	// construction direction) will process the L4 payload in the packet.
	EgressRouterAlert bool
	// Exptime is the expiry time of a HopField. The field is 1-byte long, thus there are 256
	// different values available to express an expiration time. The expiration time expressed by
	// the value of this field is relative, and an absolute expiration time in seconds is computed
	// in combination with the timestamp field (from the corresponding info field) as follows
	//
	// Timestamp + (1 + ExpTime) * (24*60*60)/256
	ExpTime uint8
	// ConsIngress is the ingress interface ID in construction direction.
	ConsIngress uint16
	// ConsEgress is the egress interface ID in construction direction.
	ConsEgress uint16
	// Mac is the 6-byte Message Authentication Code to authenticate the HopField.
	Mac []byte
}

type InfoField struct {
	// Peer is the peering flag. If set to true, then the forwarding path is built as a peering
	// path, which requires special processing on the dataplane.
	Peer bool
	// ConsDir is the construction direction flag. If set to true then the hop fields are arranged
	// in the direction they have been constructed during beaconing.
	ConsDir bool
	// SegID is a updatable field that is required for the MAC-chaining mechanism.
	SegID uint16
	// Timestamp created by the initiator of the corresponding beacon. The timestamp is expressed in
	// Unix time, and is encoded as an unsigned integer within 4 bytes with 1-second time
	// granularity.  This timestamp enables validation of the hop field by verification of the
	// expiration time and MAC.
	Timestamp uint32
}

type Metadata struct {
	// Type is a unique value for the path.
	Type Type
	// Desc is the description/name of the path.
	Desc string
	// New is a path constructor function.
	New func() Path
}

type Path interface {
	// SerializeTo serializes the path into the provided buffer.
	SerializeTo(b []byte) error
	// DecodesFromBytes decodes the path from the provided buffer.
	DecodeFromBytes(b []byte) error
	// Reverse reverses a path such that it can be used in the reversed direction.
	//
	// XXX(shitz): This method should possibly be moved to a higher-level path manipulation package.
	Reverse() (Path, error)
	// Len returns the length of a path in bytes.
	Len() int
	// Type returns the type of a path.
	Type() Type
}

type Type uint8