blasphem/pkg/auth/authenticator.go

package auth

import (
	"crypto/rand"
	"encoding/hex"
	"errors"
	"net/http"

	"github.com/google/uuid"
	"github.com/labstack/echo/v4"
	"github.com/rs/zerolog/log"

	"dynatron.me/x/blasphem/pkg/frontend"
	"dynatron.me/x/blasphem/pkg/storage"
)

var (
	ErrInvalidAuth    = errors.New("invalid auth")
	ErrInvalidHandler = errors.New("no such handler")
)

type Authenticator struct {
	store     AuthStore
	flows     FlowStore
	sessions  SessionStore
	providers map[string]AuthProvider
}

type AuthError struct {
	Error       string `json:"error"`
	Description string `json:"error_description"`
}

func (a *Authenticator) InstallRoutes(e *echo.Echo) {
	authG := e.Group("/auth")
	authG.GET("/authorize", frontend.AliasHandler("authorize.html"))
	authG.GET("/providers", a.ProvidersHandler)
	authG.POST("/token", a.TokenHandler)

	authG.POST("/login_flow", a.BeginLoginFlowHandler)

	loginFlow := authG.Group("/login_flow") // TODO: add IP address affinity middleware
	loginFlow.POST("/:flow_id", a.LoginFlowHandler)
	loginFlow.DELETE("/:flow_id", a.LoginFlowDeleteHandler)

}

func (a *Authenticator) InitAuth(s storage.Store) error {
	a.flows = make(FlowStore)
	a.sessions.init()
	hap, err := NewHAProvider(s)
	if err != nil {
		return err
	}

	// XXX: yuck. use init with a registry or something
	a.providers = map[string]AuthProvider{
		hap.ProviderType(): hap,
	}

	return nil
}

func (a *Authenticator) Provider(name string) AuthProvider {
	p, ok := a.providers[name]
	if !ok {
		return nil
	}

	return p
}

type AuthProvider interface { // TODO: this should include stepping
	ProviderName() string
	ProviderID() *string
	ProviderType() string
	ProviderBase() AuthProviderBase
	FlowSchema() []FlowSchemaItem
	ValidateCreds(reqMap map[string]interface{}) (user ProviderUser, success bool)
}

type ProviderUser interface {
	ProviderUsername() string
}

type AuthProviderBase struct {
	Name string  `json:"name"`
	ID   *string `json:"id"`
	Type string  `json:"type"`
}

func (bp *AuthProviderBase) ProviderName() string           { return bp.Name }
func (bp *AuthProviderBase) ProviderID() *string            { return bp.ID }
func (bp *AuthProviderBase) ProviderType() string           { return bp.Type }
func (bp *AuthProviderBase) ProviderBase() AuthProviderBase { return *bp }

var HomeAssistant = "homeassistant"

// TODO: make this configurable
func (a *Authenticator) ProvidersHandler(c echo.Context) error {
	providers := []AuthProviderBase{
		a.Provider(HomeAssistant).ProviderBase(),
	}

	return c.JSON(http.StatusOK, providers)
}

func (a *Authenticator) Check(f *Flow, rm map[string]interface{}) (ProviderUser, error) {
	cID, hasCID := rm["client_id"]
	cIDStr, cidIsStr := cID.(string)
	if !hasCID || !cidIsStr || cIDStr == "" || cIDStr != string(f.request.ClientID) {
		return nil, ErrInvalidAuth
	}

	for _, h := range f.Handler {
		if h == nil {
			return nil, ErrInvalidHandler
		}

		p := a.Provider(*h)
		if p == nil {
			return nil, ErrInvalidAuth
		}

		user, success := p.ValidateCreds(rm)

		if success {
			log.Info().Str("user", user.ProviderUsername()).Msg("Login success")
			return user, nil
		}
	}

	return nil, ErrInvalidAuth
}

func genUUID() string {
	// must be addressable
	u := uuid.New()

	return hex.EncodeToString(u[:])
}

func genHex(l int) string {
	b := make([]byte, l)
	if _, err := rand.Read(b); err != nil {
		panic(err)
	}

	return hex.EncodeToString(b)
}