flow

Documentation

Index

• Constants
• type Accounter
  • func NewAccounter(maxEntries int, evictTimeout time.Duration, ifaceNamer InterfaceNamer, ...) *Accounter
  • func (c *Accounter) Account(in <-chan *RawRecord, out chan<- []*Record)
• type DataLink
• type Direction
• type HumanBytes
• type IPAddr
  • func (ia *IPAddr) IP() net.IP
  • func (ia *IPAddr) IntEncodeV4() uint32
  • func (ia *IPAddr) MarshalJSON() ([]byte, error)
• type InterfaceNamer
• type MacAddr
  • func (m *MacAddr) MarshalJSON() ([]byte, error)
  • func (m *MacAddr) String() string
• type Network
• type RawRecord
  • func ReadFrom(reader io.Reader) (*RawRecord, error)
• type Record
  • func NewRecord(key RecordKey, metrics RecordMetrics, currentTime time.Time, ...) *Record
• type RecordKey
• type RecordMetrics
  • func (r *RecordMetrics) Accumulate(src *RecordMetrics)
• type Transport

Constants

const (
	DirectionIngress = uint8(0)
	DirectionEgress  = uint8(1)
)

Values according to field 61 in https://www.iana.org/assignments/ipfix/ipfix.xhtml

const IPv6Type = 0x86DD

IPv6Type value as defined in IEEE 802: https://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml

const MacLen = 6

Types

type Accounter

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

Accounter accumulates flows metrics in memory and eventually evicts them via an evictor channel. The accounting process is usually done at kernel-space. This type reimplements it at userspace for the edge case where packets are submitted directly via ring-buffer because the kernel-side accounting map is full.

func NewAccounter

func NewAccounter(
	maxEntries int, evictTimeout time.Duration, ifaceNamer InterfaceNamer,
	clock func() time.Time,
	monoClock func() time.Duration,
) *Accounter

NewAccounter creates a new Accounter. The cache has no limit and it's assumed that eviction is done by the caller.

func (*Accounter) Account

func (c *Accounter) Account(in <-chan *RawRecord, out chan<- []*Record)

Account runs in a new goroutine. It reads all the records from the input channel and accumulate their metrics internally. Once the metrics have reached their max size or the eviction times out, it evicts all the accumulated flows by the returned channel.

type DataLink

type DataLink struct {
	SrcMac MacAddr
	DstMac MacAddr
}

type Direction

type Direction uint8

type HumanBytes

type HumanBytes uint64

type IPAddr

type IPAddr [net.IPv6len]uint8

IPAddr encodes v4 and v6 IPs with a fixed length. IPv4 addresses are encoded as IPv6 addresses with prefix ::ffff/96 as described in https://datatracker.ietf.org/doc/html/rfc4038#section-4.2 (same behavior as Go's net.IP type)

func (*IPAddr) IP

func (ia *IPAddr) IP() net.IP

IP returns the net.IP equivalent object

func (*IPAddr) IntEncodeV4

func (ia *IPAddr) IntEncodeV4() uint32

IntEncodeV4 encodes an IPv4 address as an integer (in network encoding, big endian). It assumes that the passed IP is already IPv4. Otherwise it would just encode the last 4 bytes of an IPv6 address

func (*IPAddr) MarshalJSON

func (ia *IPAddr) MarshalJSON() ([]byte, error)

type InterfaceNamer

type InterfaceNamer func(ifIndex int) string

type MacAddr

type MacAddr [MacLen]uint8

func (*MacAddr) MarshalJSON

func (m *MacAddr) MarshalJSON() ([]byte, error)

func (*MacAddr) String

func (m *MacAddr) String() string

type Network

type Network struct {
	SrcAddr IPAddr
	DstAddr IPAddr
}

type RawRecord

type RawRecord struct {
	RecordKey
	RecordMetrics
}

record structure as parsed from eBPF it's important to emphasize that the fields in this structure have to coincide, byte by byte, with the flow_record_t structure in the bpf/flow.h file

func ReadFrom

func ReadFrom(reader io.Reader) (*RawRecord, error)

ReadFrom reads a Record from a binary source, in LittleEndian order

type Record

type Record struct {
	RawRecord
	// TODO: redundant field from RecordMetrics. Reorganize structs
	TimeFlowStart time.Time
	TimeFlowEnd   time.Time
	Interface     string
}

Record contains accumulated metrics from a flow

func NewRecord

func NewRecord(
	key RecordKey,
	metrics RecordMetrics,
	currentTime time.Time,
	monotonicCurrentTime uint64,
	namer InterfaceNamer,
) *Record

type RecordKey

type RecordKey struct {
	EthProtocol uint16 `json:"Etype"`
	Direction   uint8  `json:"FlowDirection"`
	DataLink
	Network
	Transport
	IFIndex uint32
}

RecordKey identifies a flow Must coincide byte by byte with kernel-side flow_id_t (bpf/flow.h)

type RecordMetrics

type RecordMetrics struct {
	Packets uint32
	Bytes   uint64
	// StartMonoTimeNs and EndMonoTimeNs are the start and end times as system monotonic timestamps
	// in nanoseconds, as output from bpf_ktime_get_ns() (kernel space)
	// and monotime.Now() (user space)
	StartMonoTimeNs uint64
	EndMonoTimeNs   uint64
}

RecordMetrics provides flows metrics and timing information Must coincide byte by byte with kernel-side flow_metrics_t (bpf/flow.h)

func (*RecordMetrics) Accumulate

func (r *RecordMetrics) Accumulate(src *RecordMetrics)

type Transport

type Transport struct {
	SrcPort  uint16
	DstPort  uint16
	Protocol uint8 `json:"Proto"`
}