tracer

Documentation

Overview

Package tracer takes care of all interactions with the traceroute tools, currently only scamper. This package supports two types of traceroutes among the many that scamper can run: MDA and regular:

• MDA traceroute (tracelb) finds load balanced paths between two addresses by varying the first 4 bytes of the transport header, but keeping the first 4 bytes constant when probing consecutive hops. the -P parameter to tracelb says what type of probes to send, and while the names have overlap with the -P parameter to trace, they mean different things.
• Regular traceroute using Paris algorithm (trace -P icmp-paris) finds a single path between two addresses by keeping the first 4 bytes of the transport header constant.

See scamper's man page for more details.

Index

• Variables
• type Metadata
• type Scamper
  • func NewScamper(cfg ScamperConfig) (*Scamper, error)
  • func (s *Scamper) CachedTrace(uuid string, t time.Time, cachedTrace []byte) ([]byte, error)
  • func (*Scamper) DontTrace()
  • func (s *Scamper) Trace(remoteIP, uuid string, t time.Time) ([]byte, error)
  • func (s *Scamper) WriteFile(uuid string, t time.Time, data []byte) error
• type ScamperConfig

Variables

var (
	// ErrEmptyUUID is returned when a required UUID is empty.
	ErrEmptyUUID = errors.New("uuid is empty")
)

Types

type Metadata

type Metadata struct {
	UUID                    string
	TracerouteCallerVersion string
	CachedResult            bool
	CachedUUID              string
}

Metadata is the first line of the traceroute .jsonl file.

TODO: move this struct to ETL parser.

type Scamper

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

Scamper invokes an instance of the scamper tool for each traceroute.

func NewScamper

func NewScamper(cfg ScamperConfig) (*Scamper, error)

NewScamper validates the specified scamper configuration and, if successful, returns a new Scamper instance. Otherwise, it returns nil and an error.

func (*Scamper) CachedTrace

func (s *Scamper) CachedTrace(uuid string, t time.Time, cachedTrace []byte) ([]byte, error)

CachedTrace creates an updated traceroute using the given uuid and time based on the traceroute cache.

func (*Scamper) DontTrace

func (*Scamper) DontTrace()

DontTrace is called when a previous traceroute that we were waiting for fails. It increments a counter that tracks the number of these failures.

func (*Scamper) Trace

func (s *Scamper) Trace(remoteIP, uuid string, t time.Time) ([]byte, error)

Trace starts a new scamper process to run a traceroute based on the traceroute type and saves it in a file.

func (*Scamper) WriteFile

func (s *Scamper) WriteFile(uuid string, t time.Time, data []byte) error

WriteFile writes the given data to a file in the configured Scamper output path using the given UUID and time.

type ScamperConfig

type ScamperConfig struct {
	Binary           string
	OutputPath       string
	Timeout          time.Duration
	TraceType        string
	TracelbPTR       bool
	TracelbWaitProbe int
}

ScamperConfig contains configuration parameters of scamper.