origin.go

// Copyright 2016 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package logfwd

import (
	"fmt"

	"github.com/juju/errors"
	"github.com/juju/names/v4"
	"github.com/juju/version"
)

// canonicalPEN is the IANA-registered Private Enterprise Number
// assigned to Canonical. Among other things, this is used in RFC 5424
// structured data.
//
// See https://www.iana.org/assignments/enterprise-numbers/enterprise-numbers.
const canonicalPEN = 28978

// These are the recognized origin types.
const (
	OriginTypeUnknown OriginType = 0
	OriginTypeUser               = iota
	OriginTypeMachine
	OriginTypeUnit
)

var originTypes = map[OriginType]string{
	OriginTypeUnknown: "unknown",
	OriginTypeUser:    names.UserTagKind,
	OriginTypeMachine: names.MachineTagKind,
	OriginTypeUnit:    names.UnitTagKind,
}

// OriginType is the "enum" type for the different kinds of log record
// origin.
type OriginType int

// ParseOriginType converts a string to an OriginType or fails if
// not able. It round-trips with String().
func ParseOriginType(value string) (OriginType, error) {
	for ot, str := range originTypes {
		if value == str {
			return ot, nil
		}
	}
	const originTypeInvalid OriginType = -1
	return originTypeInvalid, errors.Errorf("unrecognized origin type %q", value)
}

// String returns a string representation of the origin type.
func (ot OriginType) String() string {
	return originTypes[ot]
}

// Validate ensures that the origin type is correct.
func (ot OriginType) Validate() error {
	// As noted above, typedef'ing int means that the use of int
	// literals or explicit type conversion could result in unsupported
	// "enum" values. Otherwise OriginType would not need this method.
	if _, ok := originTypes[ot]; !ok {
		return errors.NewNotValid(nil, "unsupported origin type")
	}
	return nil
}

// ValidateName ensures that the given origin name is valid within the
// context of the origin type.
func (ot OriginType) ValidateName(name string) error {
	switch ot {
	case OriginTypeUnknown:
		if name != "" {
			return errors.NewNotValid(nil, "origin name must not be set if type is unknown")
		}
	case OriginTypeUser:
		if !names.IsValidUser(name) {
			return errors.NewNotValid(nil, "bad user name")
		}
	case OriginTypeMachine:
		if !names.IsValidMachine(name) {
			return errors.NewNotValid(nil, "bad machine name")
		}
	case OriginTypeUnit:
		if !names.IsValidUnit(name) {
			return errors.NewNotValid(nil, "bad unit name")
		}
	}
	return nil
}

// Origin describes what created the record.
type Origin struct {
	// ControllerUUID is the ID of the Juju controller under which the
	// record originated.
	ControllerUUID string

	// ModelUUID is the ID of the Juju model under which the record
	// originated.
	ModelUUID string

	// Hostname identifies the host where the record originated.
	Hostname string

	// Type identifies the kind of thing that generated the record.
	Type OriginType

	// Name identifies the thing that generated the record.
	Name string

	// Software identifies the running software that created the record.
	Software Software
}

// OriginForMachineAgent populates a new origin for the agent.
func OriginForMachineAgent(tag names.MachineTag, controller, model string, ver version.Number) Origin {
	return originForAgent(OriginTypeMachine, tag, controller, model, ver)
}

// OriginForUnitAgent populates a new origin for the agent.
func OriginForUnitAgent(tag names.UnitTag, controller, model string, ver version.Number) Origin {
	return originForAgent(OriginTypeUnit, tag, controller, model, ver)
}

func originForAgent(oType OriginType, tag names.Tag, controller, model string, ver version.Number) Origin {
	origin := originForJuju(oType, tag.Id(), controller, model, ver)
	origin.Hostname = fmt.Sprintf("%s.%s", tag, model)
	origin.Software.Name = fmt.Sprintf("jujud-%s-agent", tag.Kind())
	return origin
}

// OriginForJuju populates a new origin for the juju client.
func OriginForJuju(tag names.Tag, controller, model string, ver version.Number) (Origin, error) {
	oType, err := ParseOriginType(tag.Kind())
	if err != nil {
		return Origin{}, errors.Annotate(err, "invalid tag")
	}
	return originForJuju(oType, tag.Id(), controller, model, ver), nil
}

func originForJuju(oType OriginType, name, controller, model string, ver version.Number) Origin {
	return Origin{
		ControllerUUID: controller,
		ModelUUID:      model,
		Type:           oType,
		Name:           name,
		Software: Software{
			PrivateEnterpriseNumber: canonicalPEN,
			Name:                    "juju",
			Version:                 ver,
		},
	}
}

// Validate ensures that the origin is correct.
func (o Origin) Validate() error {
	if o.ControllerUUID == "" {
		return errors.NewNotValid(nil, "empty ControllerUUID")
	}
	if !names.IsValidModel(o.ControllerUUID) {
		return errors.NewNotValid(nil, fmt.Sprintf("ControllerUUID %q not a valid UUID", o.ControllerUUID))
	}

	if o.ModelUUID == "" {
		return errors.NewNotValid(nil, "empty ModelUUID")
	}
	if !names.IsValidModel(o.ModelUUID) {
		return errors.NewNotValid(nil, fmt.Sprintf("ModelUUID %q not a valid UUID", o.ModelUUID))
	}

	if err := o.Type.Validate(); err != nil {
		return errors.Annotate(err, "invalid Type")
	}

	if o.Name == "" && o.Type != OriginTypeUnknown {
		return errors.NewNotValid(nil, "empty Name")
	}
	if err := o.Type.ValidateName(o.Name); err != nil {
		return errors.Annotatef(err, "invalid Name %q", o.Name)
	}

	if !o.Software.isZero() {
		if err := o.Software.Validate(); err != nil {
			return errors.Annotate(err, "invalid Software")
		}
	}

	return nil
}

// Software describes a running application.
type Software struct {
	// PrivateEnterpriseNumber is the IANA-registered "SMI Network
	// Management Private Enterprise Code" for the software's vendor.
	//
	// See https://tools.ietf.org/html/rfc5424#section-7.2.2.
	PrivateEnterpriseNumber int

	// Name identifies the software (relative to the vendor).
	Name string

	// Version is the software's version.
	Version version.Number
}

func (sw Software) isZero() bool {
	if sw.PrivateEnterpriseNumber > 0 {
		return false
	}
	if sw.Name != "" {
		return false
	}
	if sw.Version != version.Zero {
		return false
	}
	return true
}

// Validate ensures that the software info is correct.
func (sw Software) Validate() error {
	if sw.PrivateEnterpriseNumber <= 0 {
		return errors.NewNotValid(nil, "missing PrivateEnterpriseNumber")
	}
	if sw.Name == "" {
		return errors.NewNotValid(nil, "empty Name")
	}
	if sw.Version == version.Zero {
		return errors.NewNotValid(nil, "empty Version")
	}
	return nil
}