most test passes with ext auth

backend/Gopkg.lock

@@ -9,6 +9,17 @@
   revision = "767c40d6a2e058483c25fa193e963a22da17236d"
   version = "v0.18.0"
 
+[[projects]]
+  digest = "1:6f958db63973bc397ef72acacbd56e045b4a0160af1224d6eb0f20deb860c0cd"
+  name = "git.tkginternal.com/commons/pkg/repeater"
+  packages = [
+    ".",
+    "strategy",
+  ]
+  pruneopts = "UT"
+  revision = "a207227f9303dc677c4d9644f709ad1e29bd0940"
+  version = "v1.0.0"
+
 [[projects]]
   digest = "1:bff7b2530f02b143623e260c11df5cbf34e0faeaca6aa001a8be31f333518ca9"
   name = "github.com/PuerkitoBio/goquery"
@@ -111,6 +122,20 @@
   revision = "9f855fadd4b8cde7773f9ef51f6b2705af239519"
   version = "v1.0.0"
 
+[[projects]]
+  branch = "master"
+  digest = "1:5ef69525e5e62fb771f3f6910c94030a86b542eff1cb9d9350803b6dae147144"
+  name = "github.com/go-pkgz/auth"
+  packages = [
+    ".",
+    "avatar",
+    "middleware",
+    "provider",
+    "token",
+  ]
+  pruneopts = "UT"
+  revision = "8d5238712a320d972f9d658e2fd1d4468ef81c3e"
+
 [[projects]]
   digest = "1:1212e114344a5cdcc834ea69e19d456eef230f9784659080fee67e02ba2cb574"
   name = "github.com/go-pkgz/mongo"
@@ -375,6 +400,7 @@
   analyzer-name = "dep"
   analyzer-version = 1
   input-imports = [
+    "git.tkginternal.com/commons/pkg/repeater",
     "github.com/PuerkitoBio/goquery",
     "github.com/coreos/bbolt",
     "github.com/dgrijalva/jwt-go",
@@ -386,6 +412,10 @@
     "github.com/go-chi/chi/middleware",
     "github.com/go-chi/cors",
     "github.com/go-chi/render",
+    "github.com/go-pkgz/auth",
+    "github.com/go-pkgz/auth/avatar",
+    "github.com/go-pkgz/auth/provider",
+    "github.com/go-pkgz/auth/token",
     "github.com/go-pkgz/mongo",
     "github.com/go-pkgz/repeater",
     "github.com/go-pkgz/rest",
@@ -397,19 +427,12 @@
     "github.com/hashicorp/logutils",
     "github.com/jessevdk/go-flags",
     "github.com/microcosm-cc/bluemonday",
-    "github.com/nullrocks/identicon",
     "github.com/patrickmn/go-cache",
     "github.com/pkg/errors",
     "github.com/rakyll/statik/fs",
     "github.com/stretchr/testify/assert",
     "github.com/stretchr/testify/require",
     "golang.org/x/crypto/acme/autocert",
-    "golang.org/x/image/draw",
-    "golang.org/x/oauth2",
-    "golang.org/x/oauth2/facebook",
-    "golang.org/x/oauth2/github",
-    "golang.org/x/oauth2/google",
-    "golang.org/x/oauth2/yandex",
     "gopkg.in/russross/blackfriday.v2",
   ]
   solver-name = "gps-cdcl"

backend/app/cmd/avatar.go

@@ -6,10 +6,9 @@ import (
 	"time"
 
 	"github.com/coreos/bbolt"
+	"github.com/go-pkgz/auth/avatar"
 	"github.com/go-pkgz/mongo"
 	"github.com/pkg/errors"
-
-	"github.com/umputun/remark/backend/app/store/avatar"
 )
 
 // AvatarCommand set of flags and command for avatar migration
@@ -76,19 +75,19 @@ func (ac *AvatarCommand) makeAvatarStore(gr AvatarGroup) (avatar.Store, error) {
 		if err := makeDirs(gr.FS.Path); err != nil {
 			return nil, err
 		}
-		return avatar.NewLocalFS(gr.FS.Path, gr.RszLmt), nil
+		return avatar.NewLocalFS(gr.FS.Path), nil
 	case "mongo":
 		mgServer, err := ac.makeMongo()
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to create mongo server")
 		}
 		conn := mongo.NewConnection(mgServer, ac.Mongo.DB, "")
-		return avatar.NewGridFS(conn, gr.RszLmt), nil
+		return avatar.NewGridFS(conn), nil
 	case "bolt":
 		if err := makeDirs(path.Dir(gr.Bolt.File)); err != nil {
 			return nil, err
 		}
-		return avatar.NewBoltDB(gr.Bolt.File, bolt.Options{}, gr.RszLmt)
+		return avatar.NewBoltDB(gr.Bolt.File, bolt.Options{})
 	}
 	return nil, errors.Errorf("unsupported avatar store type %s", gr.Type)
 }

backend/app/cmd/avatar_test.go

@@ -5,10 +5,10 @@ import (
 	"os"
 	"testing"
 
+	"github.com/go-pkgz/auth/avatar"
 	flags "github.com/jessevdk/go-flags"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"github.com/umputun/remark/backend/app/store/avatar"
 )
 
 func TestAvatar_Execute(t *testing.T) {

backend/app/cmd/server.go

@@ -12,19 +12,23 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/go-pkgz/auth/token"
+
 	bolt "github.com/coreos/bbolt"
+	"github.com/pkg/errors"
+
+	"github.com/go-pkgz/auth"
+	"github.com/go-pkgz/auth/avatar"
+	"github.com/go-pkgz/auth/provider"
 	"github.com/go-pkgz/mongo"
 	"github.com/go-pkgz/rest/cache"
-	"github.com/pkg/errors"
 
 	"github.com/umputun/remark/backend/app/migrator"
 	"github.com/umputun/remark/backend/app/notify"
 	"github.com/umputun/remark/backend/app/rest/api"
-	"github.com/umputun/remark/backend/app/rest/auth"
 	"github.com/umputun/remark/backend/app/rest/proxy"
 	"github.com/umputun/remark/backend/app/store"
 	"github.com/umputun/remark/backend/app/store/admin"
-	"github.com/umputun/remark/backend/app/store/avatar"
 	"github.com/umputun/remark/backend/app/store/engine"
 	"github.com/umputun/remark/backend/app/store/service"
 )
@@ -148,7 +152,7 @@ type serverApp struct {
 	restSrv       *api.Rest
 	migratorSrv   *api.Migrator
 	exporter      migrator.Exporter
-	devAuth       *auth.DevAuthServer
+	devAuth       *provider.DevAuthServer
 	dataService   *service.DataStore
 	avatarStore   avatar.Store
 	notifyService *notify.Service
@@ -217,18 +221,38 @@ func (s *ServerCommand) newServerApp() (*serverApp, error) {
 		return nil, errors.Wrap(err, "failed to make cache")
 	}
 
-	// token TTL is 5 minutes, inactivity interval 7+ days by default
-	jwtService := auth.NewJWT(adminStore, strings.HasPrefix(s.RemarkURL, "https://"), s.Auth.TTL.JWT, s.Auth.TTL.Cookie)
-
 	avatarStore, err := s.makeAvatarStore()
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to make avatar store")
 	}
-	avatarProxy := &proxy.Avatar{
-		Store:     avatarStore,
-		RoutePath: "/api/v1/avatar",
-		RemarkURL: strings.TrimSuffix(s.RemarkURL, "/"),
-	}
+
+	authenticator := auth.NewService(auth.Opts{
+		TokenDuration:  s.Auth.TTL.JWT,
+		CookieDuration: s.Auth.TTL.Cookie,
+		SecureCookies:  strings.HasPrefix(s.RemarkURL, "https://"),
+		SecretReader: token.SecretFunc(func(id string) (string, error) {
+			return adminStore.Key(id)
+		}),
+		ClaimsUpd: token.ClaimsUpdFunc(func(c token.Claims) token.Claims {
+			c.User.SetAdmin(dataService.IsAdmin(c.Audience, c.User.ID))
+			return c
+		}),
+		DevPasswd: s.DevPasswd,
+		//Validator:         dataService,
+		AvatarStore:       avatarStore,
+		AvatarResizeLimit: s.Avatar.RszLmt,
+		AvatarRoutePath:   "/api/v1/avatar",
+	})
+	s.addAuthProviders(authenticator)
+
+	// token TTL is 5 minutes, inactivity interval 7+ days by default
+	// jwtService := auth.NewJWT(adminStore, strings.HasPrefix(s.RemarkURL, "https://"), s.Auth.TTL.JWT, s.Auth.TTL.Cookie)
+
+	// avatarProxy := &proxy.Avatar{
+	// 	Store:     avatarStore,
+	// 	RoutePath: "/api/v1/avatar",
+	// 	RemarkURL: strings.TrimSuffix(s.RemarkURL, "/"),
+	// }
 
 	exporter := &migrator.Native{DataStore: dataService}
 
@@ -247,7 +271,6 @@ func (s *ServerCommand) newServerApp() (*serverApp, error) {
 		notifyService = notify.NopService // disable notifier
 	}
 
-	authProviders := s.makeAuthProviders(jwtService, avatarProxy, dataService)
 	imgProxy := &proxy.Image{Enabled: s.ImageProxy, RoutePath: "/api/v1/img", RemarkURL: s.RemarkURL}
 	commentFormatter := store.NewCommentFormatter(imgProxy)
 
@@ -263,27 +286,24 @@ func (s *ServerCommand) newServerApp() (*serverApp, error) {
 		RemarkURL:        s.RemarkURL,
 		ImageProxy:       imgProxy,
 		CommentFormatter: commentFormatter,
-		AvatarProxy:      avatarProxy,
 		Migrator:         migr,
 		ReadOnlyAge:      s.ReadOnlyAge,
 		SharedSecret:     s.SharedSecret,
-		Authenticator: auth.Authenticator{
-			JWTService:        jwtService,
-			KeyStore:          adminStore,
-			Providers:         authProviders,
-			DevPasswd:         s.DevPasswd,
-			PermissionChecker: dataService,
-		},
-		Cache:         loadingCache,
-		NotifyService: notifyService,
-		SSLConfig:     sslConfig,
+		Authenticator:    *authenticator,
+		Cache:            loadingCache,
+		NotifyService:    notifyService,
+		SSLConfig:        sslConfig,
 	}
 
 	srv.ScoreThresholds.Low, srv.ScoreThresholds.Critical = s.LowScore, s.CriticalScore
 
-	var devAuth *auth.DevAuthServer
+	var devAuth provider.DevAuthServer
 	if s.Auth.Dev {
-		devAuth = &auth.DevAuthServer{Provider: authProviders[len(authProviders)-1]}
+		p, err := authenticator.Provider("dev")
+		if err != nil {
+			return nil, errors.Wrap(err, "can't pick dev provider")
+		}
+		devAuth = provider.DevAuthServer{Provider: p}
 	}
 
 	return &serverApp{
@@ -291,7 +311,7 @@ func (s *ServerCommand) newServerApp() (*serverApp, error) {
 		restSrv:       srv,
 		migratorSrv:   migr,
 		exporter:      exporter,
-		devAuth:       devAuth,
+		devAuth:       &devAuth,
 		dataService:   dataService,
 		avatarStore:   avatarStore,
 		notifyService: notifyService,
@@ -385,19 +405,19 @@ func (s *ServerCommand) makeAvatarStore() (avatar.Store, error) {
 		if err := makeDirs(s.Avatar.FS.Path); err != nil {
 			return nil, err
 		}
-		return avatar.NewLocalFS(s.Avatar.FS.Path, s.Avatar.RszLmt), nil
+		return avatar.NewLocalFS(s.Avatar.FS.Path), nil
 	case "mongo":
 		mgServer, err := s.makeMongo()
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to create mongo server")
 		}
 		conn := mongo.NewConnection(mgServer, s.Mongo.DB, "")
-		return avatar.NewGridFS(conn, s.Avatar.RszLmt), nil
+		return avatar.NewGridFS(conn), nil
 	case "bolt":
 		if err := makeDirs(path.Dir(s.Avatar.Bolt.File)); err != nil {
 			return nil, err
 		}
-		return avatar.NewBoltDB(s.Avatar.Bolt.File, bolt.Options{}, s.Avatar.RszLmt)
+		return avatar.NewBoltDB(s.Avatar.Bolt.File, bolt.Options{})
 	}
 	return nil, errors.Errorf("unsupported avatar store type %s", s.Avatar.Type)
 }
@@ -452,40 +472,33 @@ func (s *ServerCommand) makeMongo() (result *mongo.Server, err error) {
 	return mongo.NewServerWithURL(s.Mongo.URL, 10*time.Second)
 }
 
-func (s *ServerCommand) makeAuthProviders(jwt *auth.JWT, ap *proxy.Avatar, ds *service.DataStore) []auth.Provider {
+func (s *ServerCommand) addAuthProviders(authenticator *auth.Service) {
 
-	makeParams := func(cid, secret string) auth.Params {
-		return auth.Params{
-			JwtService:        jwt,
-			AvatarProxy:       ap,
-			RemarkURL:         s.RemarkURL,
-			Cid:               cid,
-			Csecret:           secret,
-			PermissionChecker: ds,
-		}
-	}
-
-	providers := []auth.Provider{}
+	providers := 0
 	if s.Auth.Google.CID != "" && s.Auth.Google.CSEC != "" {
-		providers = append(providers, auth.NewGoogle(makeParams(s.Auth.Google.CID, s.Auth.Google.CSEC)))
+		authenticator.AddProvider("google", s.Auth.Google.CID, s.Auth.Google.CSEC)
+		providers++
 	}
 	if s.Auth.Github.CID != "" && s.Auth.Github.CSEC != "" {
-		providers = append(providers, auth.NewGithub(makeParams(s.Auth.Github.CID, s.Auth.Github.CSEC)))
+		authenticator.AddProvider("github", s.Auth.Github.CID, s.Auth.Github.CSEC)
+		providers++
 	}
 	if s.Auth.Facebook.CID != "" && s.Auth.Facebook.CSEC != "" {
-		providers = append(providers, auth.NewFacebook(makeParams(s.Auth.Facebook.CID, s.Auth.Facebook.CSEC)))
+		authenticator.AddProvider("facebook", s.Auth.Facebook.CID, s.Auth.Facebook.CSEC)
+		providers++
 	}
 	if s.Auth.Yandex.CID != "" && s.Auth.Yandex.CSEC != "" {
-		providers = append(providers, auth.NewYandex(makeParams(s.Auth.Yandex.CID, s.Auth.Yandex.CSEC)))
+		authenticator.AddProvider("yandex", s.Auth.Yandex.CID, s.Auth.Yandex.CSEC)
+		providers++
 	}
 	if s.Auth.Dev {
-		providers = append(providers, auth.NewDev(makeParams("", "")))
+		authenticator.AddProvider("dev", "", "")
+		providers++
 	}
 
-	if len(providers) == 0 {
+	if providers == 0 {
 		log.Printf("[WARN] no auth providers defined")
 	}
-	return providers
 }
 
 func (s *ServerCommand) makeNotify(dataStore *service.DataStore) (*notify.Service, error) {

backend/app/cmd/server_test.go

@@ -39,8 +39,12 @@ func TestServerApp(t *testing.T) {
 	assert.Equal(t, "pong", string(body))
 
 	// add comment
-	resp, err = http.Post("http://dev:password@localhost:18080/api/v1/comment", "json",
+	client := http.Client{Timeout: 5 * time.Second}
+	req, err := http.NewRequest("POST", "http://localhost:18080/api/v1/comment",
 		strings.NewReader(`{"text": "test 123", "locator":{"url": "https://radio-t.com/blah1", "site": "remark"}}`))
+	req.SetBasicAuth("dev", "password")
+	require.Nil(t, err)
+	resp, err = client.Do(req)
 	require.Nil(t, err)
 	assert.Equal(t, http.StatusCreated, resp.StatusCode)
 	body, _ = ioutil.ReadAll(resp.Body)
@@ -62,8 +66,8 @@ func TestServerApp_DevMode(t *testing.T) {
 	go func() { _ = app.run(ctx) }()
 	time.Sleep(100 * time.Millisecond) // let server start
 
-	assert.Equal(t, 4+1, len(app.restSrv.Authenticator.Providers), "extra auth provider")
-	assert.Equal(t, "dev", app.restSrv.Authenticator.Providers[4].Name, "dev auth provider")
+	assert.Equal(t, 4+1, len(app.restSrv.Authenticator.Providers()), "extra auth provider")
+	assert.Equal(t, "dev", app.restSrv.Authenticator.Providers()[4].Name, "dev auth provider")
 	// send ping
 	resp, err := http.Get("http://localhost:18085/api/v1/ping")
 	require.Nil(t, err)

backend/vendor/git.tkginternal.com/commons/pkg/repeater/.gitlab-ci.yml

@@ -0,0 +1,25 @@
+image: docker.tkginternal.com/system/buildimage-go:1.1-master
+
+stages:
+    - build
+
+variables:
+    PROJ: "repeater"
+    GROUP: "commons/pkg"
+    PKG: "git.tkginternal.com"
+
+build_app:
+    stage: build
+    script:
+        - mkdir -p /go/src/$PKG/$GROUP && cp -fR $CI_PROJECT_DIR /go/src/$PKG/$GROUP/$PROJ
+        - mkdir -p $CI_PROJECT_DIR/target && ln -s $CI_PROJECT_DIR/target /go/src/$PKG/$GROUP/$PROJ/target
+        - cd /go/src/$PKG/$GROUP/$PROJ
+        - go get -v && go get -t $(go list -e ./... | grep -v vendor) && go test -v $(go list -e ./... | grep -v vendor)
+        - gometalinter --exclude=test --vendored-linters --disable-all --vendor --enable=vet --enable=vetshadow --enable=golint  --enable=ineffassign --enable=goconst --enable=gas --enable=staticcheck --enable=errcheck --deadline=120s ./...
+        - go build -ldflags "-X main.revision=$REV" -o $CI_PROJECT_DIR/target/$PROJ
+        - cd /go/src/$PKG/$GROUP/$PROJ && /script/coverage.sh
+    tags:
+        - gobuilder
+    artifacts:
+        paths:
+            - target/

backend/vendor/git.tkginternal.com/commons/pkg/repeater/README.md

@@ -0,0 +1,41 @@
+# Repeater
+
+[![pipeline status](https://git.tkginternal.com/commons/pkg/repeater/badges/master/pipeline.svg)](https://git.tkginternal.com/commons/pkg/repeater/commits/master) 
+[![coverage report](https://git.tkginternal.com/commons/pkg/repeater/badges/master/coverage.svg)](https://git.tkginternal.com/commons/pkg/repeater/commits/master)
+[![GoDoc](https://godoc.tkginternal.com/godoc.svg)](https://godoc.tkginternal.com/pkg/git.tkginternal.com/commons/pkg/repeater/)
+
+
+Package repeater call fun till it returns no error, up to repeat some number of iterations and delays defined by strategy.
+Repeats number and delays defined by strategy.Interface. Terminates immediately on err from provided, optional list of critical errors
+
+## Install and update
+
+`go get -u git.tkginternal.com/commons/pkg/repeater`
+
+## How to use
+
+New Repeater created by `New(strtg strategy.Interface)` or shortcut for defaults - `NewDefault(repeats int, delay time.Duration) *Repeater`.
+
+To activate use `Do` method. Do repeats fun till no error. Predefined (optional) errors terminate immediately
+                            
+`func (r Repeater) Do(fun func() error, errors ...error) (err error)`
+
+### Repeating strategy
+
+User can provide his own strategy implementing this interface:
+
+```go
+type Interface interface {
+	Start(ctx context.Context) chan struct{}
+}
+```
+
+Returned channels used as "ticks", i.e. for each repeat (or initial) operation one read from this channel needed. Closing this channel indicates "done with retries". This is pretty much the same idea as `time.Timer` or `time.Tick` implements. Note - the first (technically not-repeated-yet) call won't happen **until something sent to the channel**. This is why typical strategy sends first "tick" prior to first wait/sleep.
+
+Three mist common strategies provided by package and ready to use:
+1. **Fixed delay**, up to max number of attempts - `NewFixedDelay(repeats int, delay time.Duration)`. 
+This is default strategy used by `repeater.NewDefault` constructor
+2. **BackOff** with jitter provides exponential backoff. It starts from 100ms interval and goes in steps with `last * math.Pow(factor, attempt)`. Optional jitter randomizes intervals a little bit. The strategy created by `NewBackoff(repeats int, factor float64, jitter bool)`. _Factor = 1 effectively makes this strategy fixed with 100ms delay._ 
+
+3. **Once** strategy does not do any repeats and mainly useful for tests - `NewOnce()`
+

backend/vendor/git.tkginternal.com/commons/pkg/repeater/repeater.go

@@ -0,0 +1,60 @@
+// Package repeater call fun till it returns no error, up to repeat some number of iterations and delays defined by strategy.
+// Repeats number and delays defined by strategy.Interface. Terminates immediately on err from
+// provided, optional list of critical errors
+package repeater
+
+import (
+	"context"
+	"time"
+
+	"git.tkginternal.com/commons/pkg/repeater/strategy"
+)
+
+// Repeater is the main object, should be made by New or NewDefault, embeds strategy
+type Repeater struct {
+	strategy.Interface
+}
+
+// New repeater with a given strategy. If strategy=nil initializes with FixedDelay 5sec, 10 times.
+func New(strtg strategy.Interface) *Repeater {
+	if strtg == nil {
+		strtg = strategy.NewFixedDelay(10, time.Second*5)
+	}
+	result := Repeater{Interface: strtg}
+	return &result
+}
+
+// NewDefault makes repeater with FixedDelay strategy
+func NewDefault(repeats int, delay time.Duration) *Repeater {
+	return New(strategy.NewFixedDelay(repeats, delay))
+}
+
+// Do repeats fun till no error. Predefined (optional) errors terminate immediately
+func (r Repeater) Do(fun func() error, errors ...error) (err error) {
+
+	ctx, cancelFunc := context.WithCancel(context.Background())
+	defer cancelFunc() // ensure strategy's channel termination
+
+	inErrors := func(err error) bool {
+		for _, e := range errors {
+			if e == err {
+				return true
+			}
+		}
+		return false
+	}
+
+	ch := r.Start(ctx) // channel of ticks-like events provided by strategy
+
+	// closed channel indicates completion or early termination, set by strategy
+	for range ch {
+
+		if err = fun(); err == nil {
+			return nil
+		}
+		if err != nil && inErrors(err) { //terminate on critical error from provided list
+			return err
+		}
+	}
+	return err
+}

backend/vendor/git.tkginternal.com/commons/pkg/repeater/strategy/backoff.go

@@ -0,0 +1,56 @@
+package strategy
+
+import (
+	"context"
+	"math"
+	"math/rand"
+	"time"
+)
+
+// Backoff implements Interface for exponential-backoff
+// it starts from 100ms and goes in steps with last * math.Pow(factor, attempt)
+// optional jitter randomize intervals a little bit.
+type Backoff struct {
+	repeats int
+	factor  float64
+	jitter  bool
+}
+
+// NewBackoff makes Backoff strategy with given factor and optional jitter
+func NewBackoff(repeats int, factor float64, jitter bool) Interface {
+	if repeats == 0 {
+		repeats = 1
+	}
+	if factor <= 0 {
+		factor = 1
+	}
+	result := Backoff{repeats: repeats, factor: factor, jitter: jitter}
+	return &result
+}
+
+// Start returns channel, similar to time.Timer
+// then publishing signals to channel ch for retries attempt. Closed ch indicates "done" event
+// consumer (repeater) should stop it explicitly after completion
+func (b *Backoff) Start(ctx context.Context) (ch chan struct{}) {
+	ch = make(chan struct{})
+	go func() {
+		defer close(ch)
+		rnd := rand.New(rand.NewSource(int64(time.Now().Nanosecond())))
+		minDelay := 100 * time.Millisecond // starts 100ms
+		for i := 0; i < b.repeats; i++ {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				ch <- struct{}{}
+				delay := float64(minDelay) * math.Pow(b.factor, float64(i))
+				if b.jitter {
+					delay = rnd.Float64()*(float64(2*minDelay)) + (delay - float64(minDelay))
+				}
+				// log.Printf("%v", time.Duration(delay))
+				time.Sleep(time.Duration(delay))
+			}
+		}
+	}()
+	return ch
+}

backend/vendor/git.tkginternal.com/commons/pkg/repeater/strategy/fixed.go

@@ -0,0 +1,41 @@
+package strategy
+
+import (
+	"context"
+	"time"
+)
+
+// FixedDelay implements Interface for fixed intervals up to max repeats
+type FixedDelay struct {
+	repeats int
+	delay   time.Duration
+}
+
+// NewFixedDelay makes a Interface
+func NewFixedDelay(repeats int, delay time.Duration) Interface {
+	if repeats == 0 {
+		repeats = 1
+	}
+	result := FixedDelay{repeats: repeats, delay: delay}
+	return &result
+}
+
+// Start returns channel, similar to time.Timer
+// then publishing signals to channel ch for retries attempt.
+// can be terminated (canceled) via context.
+func (s *FixedDelay) Start(ctx context.Context) (ch chan struct{}) {
+	ch = make(chan struct{})
+	go func() {
+		defer close(ch)
+		for i := 0; i < s.repeats; i++ {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				ch <- struct{}{}
+				time.Sleep(s.delay)
+			}
+		}
+	}()
+	return ch
+}

backend/vendor/git.tkginternal.com/commons/pkg/repeater/strategy/strategy.go

@@ -0,0 +1,28 @@
+// Package strategy defines repeater's strategy and implements some. Strategy result
+// is channel acting like time.Timer ot time.Tick
+package strategy
+
+import "context"
+
+// Interface for repeats strategy. Returns channel with ticks
+type Interface interface {
+	Start(ctx context.Context) chan struct{}
+}
+
+// Once strategy eliminate repeats and makes a single try only
+type Once struct{}
+
+// NewOnce makes no-repeat strategy
+func NewOnce() Interface {
+	return &Once{}
+}
+
+// Start returns closed channel with a single element to prevent any repeats
+func (s *Once) Start(ctx context.Context) (ch chan struct{}) {
+	ch = make(chan struct{})
+	go func() {
+		ch <- struct{}{}
+		close(ch)
+	}()
+	return ch
+}

backend/vendor/github.com/dgrijalva/jwt-go/.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+bin
+
+

backend/vendor/github.com/dgrijalva/jwt-go/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+script:
+    - go vet ./...
+    - go test -v ./...
+
+go:
+  - 1.3
+  - 1.4
+  - 1.5
+  - 1.6
+  - 1.7
+  - tip

backend/vendor/github.com/dgrijalva/jwt-go/LICENSE

@@ -0,0 +1,8 @@
+Copyright (c) 2012 Dave Grijalva
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

backend/vendor/github.com/dgrijalva/jwt-go/MIGRATION_GUIDE.md

@@ -0,0 +1,97 @@
+## Migration Guide from v2 -> v3
+
+Version 3 adds several new, frequently requested features.  To do so, it introduces a few breaking changes.  We've worked to keep these as minimal as possible.  This guide explains the breaking changes and how you can quickly update your code.
+
+### `Token.Claims` is now an interface type
+
+The most requested feature from the 2.0 verison of this library was the ability to provide a custom type to the JSON parser for claims. This was implemented by introducing a new interface, `Claims`, to replace `map[string]interface{}`.  We also included two concrete implementations of `Claims`: `MapClaims` and `StandardClaims`.
+
+`MapClaims` is an alias for `map[string]interface{}` with built in validation behavior.  It is the default claims type when using `Parse`.  The usage is unchanged except you must type cast the claims property.
+
+The old example for parsing a token looked like this..
+
+```go
+	if token, err := jwt.Parse(tokenString, keyLookupFunc); err == nil {
+		fmt.Printf("Token for user %v expires %v", token.Claims["user"], token.Claims["exp"])
+	}
+```
+
+is now directly mapped to...
+
+```go
+	if token, err := jwt.Parse(tokenString, keyLookupFunc); err == nil {
+		claims := token.Claims.(jwt.MapClaims)
+		fmt.Printf("Token for user %v expires %v", claims["user"], claims["exp"])
+	}
+```
+
+`StandardClaims` is designed to be embedded in your custom type.  You can supply a custom claims type with the new `ParseWithClaims` function.  Here's an example of using a custom claims type.
+
+```go
+	type MyCustomClaims struct {
+		User string
+		*StandardClaims
+	}
+	
+	if token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, keyLookupFunc); err == nil {
+		claims := token.Claims.(*MyCustomClaims)
+		fmt.Printf("Token for user %v expires %v", claims.User, claims.StandardClaims.ExpiresAt)
+	}
+```
+
+### `ParseFromRequest` has been moved
+
+To keep this library focused on the tokens without becoming overburdened with complex request processing logic, `ParseFromRequest` and its new companion `ParseFromRequestWithClaims` have been moved to a subpackage, `request`.  The method signatues have also been augmented to receive a new argument: `Extractor`.
+
+`Extractors` do the work of picking the token string out of a request.  The interface is simple and composable.
+
+This simple parsing example:
+
+```go
+	if token, err := jwt.ParseFromRequest(tokenString, req, keyLookupFunc); err == nil {
+		fmt.Printf("Token for user %v expires %v", token.Claims["user"], token.Claims["exp"])
+	}
+```
+
+is directly mapped to:
+
+```go
+	if token, err := request.ParseFromRequest(req, request.OAuth2Extractor, keyLookupFunc); err == nil {
+		claims := token.Claims.(jwt.MapClaims)
+		fmt.Printf("Token for user %v expires %v", claims["user"], claims["exp"])
+	}
+```
+
+There are several concrete `Extractor` types provided for your convenience:
+
+* `HeaderExtractor` will search a list of headers until one contains content.
+* `ArgumentExtractor` will search a list of keys in request query and form arguments until one contains content.
+* `MultiExtractor` will try a list of `Extractors` in order until one returns content.
+* `AuthorizationHeaderExtractor` will look in the `Authorization` header for a `Bearer` token.
+* `OAuth2Extractor` searches the places an OAuth2 token would be specified (per the spec): `Authorization` header and `access_token` argument
+* `PostExtractionFilter` wraps an `Extractor`, allowing you to process the content before it's parsed.  A simple example is stripping the `Bearer ` text from a header
+
+
+### RSA signing methods no longer accept `[]byte` keys
+
+Due to a [critical vulnerability](https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/), we've decided the convenience of accepting `[]byte` instead of `rsa.PublicKey` or `rsa.PrivateKey` isn't worth the risk of misuse.
+
+To replace this behavior, we've added two helper methods: `ParseRSAPrivateKeyFromPEM(key []byte) (*rsa.PrivateKey, error)` and `ParseRSAPublicKeyFromPEM(key []byte) (*rsa.PublicKey, error)`.  These are just simple helpers for unpacking PEM encoded PKCS1 and PKCS8 keys. If your keys are encoded any other way, all you need to do is convert them to the `crypto/rsa` package's types.
+
+```go 
+	func keyLookupFunc(*Token) (interface{}, error) {
+		// Don't forget to validate the alg is what you expect:
+		if _, ok := token.Method.(*jwt.SigningMethodRSA); !ok {
+			return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
+		}
+		
+		// Look up key 
+		key, err := lookupPublicKey(token.Header["kid"])
+		if err != nil {
+			return nil, err
+		}
+		
+		// Unpack key from PEM encoded PKCS8
+		return jwt.ParseRSAPublicKeyFromPEM(key)
+	}
+```

backend/vendor/github.com/dgrijalva/jwt-go/README.md

@@ -0,0 +1,100 @@
+# jwt-go
+
+[![Build Status](https://travis-ci.org/dgrijalva/jwt-go.svg?branch=master)](https://travis-ci.org/dgrijalva/jwt-go)
+[![GoDoc](https://godoc.org/github.com/dgrijalva/jwt-go?status.svg)](https://godoc.org/github.com/dgrijalva/jwt-go)
+
+A [go](http://www.golang.org) (or 'golang' for search engine friendliness) implementation of [JSON Web Tokens](http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html)
+
+**NEW VERSION COMING:** There have been a lot of improvements suggested since the version 3.0.0 released in 2016. I'm working now on cutting two different releases: 3.2.0 will contain any non-breaking changes or enhancements. 4.0.0 will follow shortly which will include breaking changes. See the 4.0.0 milestone to get an idea of what's coming. If you have other ideas, or would like to participate in 4.0.0, now's the time. If you depend on this library and don't want to be interrupted, I recommend you use your dependency mangement tool to pin to version 3. 
+
+**SECURITY NOTICE:** Some older versions of Go have a security issue in the cryotp/elliptic. Recommendation is to upgrade to at least 1.8.3. See issue #216 for more detail.
+
+**SECURITY NOTICE:** It's important that you [validate the `alg` presented is what you expect](https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/). This library attempts to make it easy to do the right thing by requiring key types match the expected alg, but you should take the extra step to verify it in your usage.  See the examples provided.
+
+## What the heck is a JWT?
+
+JWT.io has [a great introduction](https://jwt.io/introduction) to JSON Web Tokens.
+
+In short, it's a signed JSON object that does something useful (for example, authentication).  It's commonly used for `Bearer` tokens in Oauth 2.  A token is made of three parts, separated by `.`'s.  The first two parts are JSON objects, that have been [base64url](http://tools.ietf.org/html/rfc4648) encoded.  The last part is the signature, encoded the same way.
+
+The first part is called the header.  It contains the necessary information for verifying the last part, the signature.  For example, which encryption method was used for signing and what key was used.
+
+The part in the middle is the interesting bit.  It's called the Claims and contains the actual stuff you care about.  Refer to [the RFC](http://self-issued.info/docs/draft-jones-json-web-token.html) for information about reserved keys and the proper way to add your own.
+
+## What's in the box?
+
+This library supports the parsing and verification as well as the generation and signing of JWTs.  Current supported signing algorithms are HMAC SHA, RSA, RSA-PSS, and ECDSA, though hooks are present for adding your own.
+
+## Examples
+
+See [the project documentation](https://godoc.org/github.com/dgrijalva/jwt-go) for examples of usage:
+
+* [Simple example of parsing and validating a token](https://godoc.org/github.com/dgrijalva/jwt-go#example-Parse--Hmac)
+* [Simple example of building and signing a token](https://godoc.org/github.com/dgrijalva/jwt-go#example-New--Hmac)
+* [Directory of Examples](https://godoc.org/github.com/dgrijalva/jwt-go#pkg-examples)
+
+## Extensions
+
+This library publishes all the necessary components for adding your own signing methods.  Simply implement the `SigningMethod` interface and register a factory method using `RegisterSigningMethod`.  
+
+Here's an example of an extension that integrates with the Google App Engine signing tools: https://github.com/someone1/gcp-jwt-go
+
+## Compliance
+
+This library was last reviewed to comply with [RTF 7519](http://www.rfc-editor.org/info/rfc7519) dated May 2015 with a few notable differences:
+
+* In order to protect against accidental use of [Unsecured JWTs](http://self-issued.info/docs/draft-ietf-oauth-json-web-token.html#UnsecuredJWT), tokens using `alg=none` will only be accepted if the constant `jwt.UnsafeAllowNoneSignatureType` is provided as the key.
+
+## Project Status & Versioning
+
+This library is considered production ready.  Feedback and feature requests are appreciated.  The API should be considered stable.  There should be very few backwards-incompatible changes outside of major version updates (and only with good reason).
+
+This project uses [Semantic Versioning 2.0.0](http://semver.org).  Accepted pull requests will land on `master`.  Periodically, versions will be tagged from `master`.  You can find all the releases on [the project releases page](https://github.com/dgrijalva/jwt-go/releases).
+
+While we try to make it obvious when we make breaking changes, there isn't a great mechanism for pushing announcements out to users.  You may want to use this alternative package include: `gopkg.in/dgrijalva/jwt-go.v3`.  It will do the right thing WRT semantic versioning.
+
+**BREAKING CHANGES:*** 
+* Version 3.0.0 includes _a lot_ of changes from the 2.x line, including a few that break the API.  We've tried to break as few things as possible, so there should just be a few type signature changes.  A full list of breaking changes is available in `VERSION_HISTORY.md`.  See `MIGRATION_GUIDE.md` for more information on updating your code.
+
+## Usage Tips
+
+### Signing vs Encryption
+
+A token is simply a JSON object that is signed by its author. this tells you exactly two things about the data:
+
+* The author of the token was in the possession of the signing secret
+* The data has not been modified since it was signed
+
+It's important to know that JWT does not provide encryption, which means anyone who has access to the token can read its contents. If you need to protect (encrypt) the data, there is a companion spec, `JWE`, that provides this functionality. JWE is currently outside the scope of this library.
+
+### Choosing a Signing Method
+
+There are several signing methods available, and you should probably take the time to learn about the various options before choosing one.  The principal design decision is most likely going to be symmetric vs asymmetric.
+
+Symmetric signing methods, such as HSA, use only a single secret. This is probably the simplest signing method to use since any `[]byte` can be used as a valid secret. They are also slightly computationally faster to use, though this rarely is enough to matter. Symmetric signing methods work the best when both producers and consumers of tokens are trusted, or even the same system. Since the same secret is used to both sign and validate tokens, you can't easily distribute the key for validation.
+
+Asymmetric signing methods, such as RSA, use different keys for signing and verifying tokens. This makes it possible to produce tokens with a private key, and allow any consumer to access the public key for verification.
+
+### Signing Methods and Key Types
+
+Each signing method expects a different object type for its signing keys. See the package documentation for details. Here are the most common ones:
+
+* The [HMAC signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodHMAC) (`HS256`,`HS384`,`HS512`) expect `[]byte` values for signing and validation
+* The [RSA signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodRSA) (`RS256`,`RS384`,`RS512`) expect `*rsa.PrivateKey` for signing and `*rsa.PublicKey` for validation
+* The [ECDSA signing method](https://godoc.org/github.com/dgrijalva/jwt-go#SigningMethodECDSA) (`ES256`,`ES384`,`ES512`) expect `*ecdsa.PrivateKey` for signing and `*ecdsa.PublicKey` for validation
+
+### JWT and OAuth
+
+It's worth mentioning that OAuth and JWT are not the same thing. A JWT token is simply a signed JSON object. It can be used anywhere such a thing is useful. There is some confusion, though, as JWT is the most common type of bearer token used in OAuth2 authentication.
+
+Without going too far down the rabbit hole, here's a description of the interaction of these technologies:
+
+* OAuth is a protocol for allowing an identity provider to be separate from the service a user is logging in to. For example, whenever you use Facebook to log into a different service (Yelp, Spotify, etc), you are using OAuth.
+* OAuth defines several options for passing around authentication data. One popular method is called a "bearer token". A bearer token is simply a string that _should_ only be held by an authenticated user. Thus, simply presenting this token proves your identity. You can probably derive from here why a JWT might make a good bearer token.
+* Because bearer tokens are used for authentication, it's important they're kept secret. This is why transactions that use bearer tokens typically happen over SSL.
+
+## More
+
+Documentation can be found [on godoc.org](http://godoc.org/github.com/dgrijalva/jwt-go).
+
+The command line utility included in this project (cmd/jwt) provides a straightforward example of token creation and parsing as well as a useful tool for debugging your own integration. You'll also find several implementation examples in the documentation.

backend/vendor/github.com/dgrijalva/jwt-go/VERSION_HISTORY.md

@@ -0,0 +1,118 @@
+## `jwt-go` Version History
+
+#### 3.2.0
+
+* Added method `ParseUnverified` to allow users to split up the tasks of parsing and validation
+* HMAC signing method returns `ErrInvalidKeyType` instead of `ErrInvalidKey` where appropriate
+* Added options to `request.ParseFromRequest`, which allows for an arbitrary list of modifiers to parsing behavior. Initial set include `WithClaims` and `WithParser`. Existing usage of this function will continue to work as before.
+* Deprecated `ParseFromRequestWithClaims` to simplify API in the future.
+
+#### 3.1.0
+
+* Improvements to `jwt` command line tool
+* Added `SkipClaimsValidation` option to `Parser`
+* Documentation updates
+
+#### 3.0.0
+
+* **Compatibility Breaking Changes**: See MIGRATION_GUIDE.md for tips on updating your code
+	* Dropped support for `[]byte` keys when using RSA signing methods.  This convenience feature could contribute to security vulnerabilities involving mismatched key types with signing methods.
+	* `ParseFromRequest` has been moved to `request` subpackage and usage has changed
+	* The `Claims` property on `Token` is now type `Claims` instead of `map[string]interface{}`.  The default value is type `MapClaims`, which is an alias to `map[string]interface{}`.  This makes it possible to use a custom type when decoding claims.
+* Other Additions and Changes
+	* Added `Claims` interface type to allow users to decode the claims into a custom type
+	* Added `ParseWithClaims`, which takes a third argument of type `Claims`.  Use this function instead of `Parse` if you have a custom type you'd like to decode into.
+	* Dramatically improved the functionality and flexibility of `ParseFromRequest`, which is now in the `request` subpackage
+	* Added `ParseFromRequestWithClaims` which is the `FromRequest` equivalent of `ParseWithClaims`
+	* Added new interface type `Extractor`, which is used for extracting JWT strings from http requests.  Used with `ParseFromRequest` and `ParseFromRequestWithClaims`.
+	* Added several new, more specific, validation errors to error type bitmask
+	* Moved examples from README to executable example files
+	* Signing method registry is now thread safe
+	* Added new property to `ValidationError`, which contains the raw error returned by calls made by parse/verify (such as those returned by keyfunc or json parser)
+
+#### 2.7.0
+
+This will likely be the last backwards compatible release before 3.0.0, excluding essential bug fixes.
+
+* Added new option `-show` to the `jwt` command that will just output the decoded token without verifying
+* Error text for expired tokens includes how long it's been expired
+* Fixed incorrect error returned from `ParseRSAPublicKeyFromPEM`
+* Documentation updates
+
+#### 2.6.0
+
+* Exposed inner error within ValidationError
+* Fixed validation errors when using UseJSONNumber flag
+* Added several unit tests
+
+#### 2.5.0
+
+* Added support for signing method none.  You shouldn't use this.  The API tries to make this clear.
+* Updated/fixed some documentation
+* Added more helpful error message when trying to parse tokens that begin with `BEARER `
+
+#### 2.4.0
+
+* Added new type, Parser, to allow for configuration of various parsing parameters
+	* You can now specify a list of valid signing methods.  Anything outside this set will be rejected.
+	* You can now opt to use the `json.Number` type instead of `float64` when parsing token JSON
+* Added support for [Travis CI](https://travis-ci.org/dgrijalva/jwt-go)
+* Fixed some bugs with ECDSA parsing
+
+#### 2.3.0
+
+* Added support for ECDSA signing methods
+* Added support for RSA PSS signing methods (requires go v1.4)
+
+#### 2.2.0
+
+* Gracefully handle a `nil` `Keyfunc` being passed to `Parse`.  Result will now be the parsed token and an error, instead of a panic.
+
+#### 2.1.0
+
+Backwards compatible API change that was missed in 2.0.0.
+
+* The `SignedString` method on `Token` now takes `interface{}` instead of `[]byte`
+
+#### 2.0.0
+
+There were two major reasons for breaking backwards compatibility with this update.  The first was a refactor required to expand the width of the RSA and HMAC-SHA signing implementations.  There will likely be no required code changes to support this change.
+
+The second update, while unfortunately requiring a small change in integration, is required to open up this library to other signing methods.  Not all keys used for all signing methods have a single standard on-disk representation.  Requiring `[]byte` as the type for all keys proved too limiting.  Additionally, this implementation allows for pre-parsed tokens to be reused, which might matter in an application that parses a high volume of tokens with a small set of keys.  Backwards compatibilty has been maintained for passing `[]byte` to the RSA signing methods, but they will also accept `*rsa.PublicKey` and `*rsa.PrivateKey`.
+
+It is likely the only integration change required here will be to change `func(t *jwt.Token) ([]byte, error)` to `func(t *jwt.Token) (interface{}, error)` when calling `Parse`.
+
+* **Compatibility Breaking Changes**
+	* `SigningMethodHS256` is now `*SigningMethodHMAC` instead of `type struct`
+	* `SigningMethodRS256` is now `*SigningMethodRSA` instead of `type struct`
+	* `KeyFunc` now returns `interface{}` instead of `[]byte`
+	* `SigningMethod.Sign` now takes `interface{}` instead of `[]byte` for the key
+	* `SigningMethod.Verify` now takes `interface{}` instead of `[]byte` for the key
+* Renamed type `SigningMethodHS256` to `SigningMethodHMAC`.  Specific sizes are now just instances of this type.
+    * Added public package global `SigningMethodHS256`
+    * Added public package global `SigningMethodHS384`
+    * Added public package global `SigningMethodHS512`
+* Renamed type `SigningMethodRS256` to `SigningMethodRSA`.  Specific sizes are now just instances of this type.
+    * Added public package global `SigningMethodRS256`
+    * Added public package global `SigningMethodRS384`
+    * Added public package global `SigningMethodRS512`
+* Moved sample private key for HMAC tests from an inline value to a file on disk.  Value is unchanged.
+* Refactored the RSA implementation to be easier to read
+* Exposed helper methods `ParseRSAPrivateKeyFromPEM` and `ParseRSAPublicKeyFromPEM`
+
+#### 1.0.2
+
+* Fixed bug in parsing public keys from certificates
+* Added more tests around the parsing of keys for RS256
+* Code refactoring in RS256 implementation.  No functional changes
+
+#### 1.0.1
+
+* Fixed panic if RS256 signing method was passed an invalid key
+
+#### 1.0.0
+
+* First versioned release
+* API stabilized
+* Supports creating, signing, parsing, and validating JWT tokens
+* Supports RS256 and HS256 signing methods

backend/vendor/github.com/dgrijalva/jwt-go/claims.go

@@ -0,0 +1,134 @@
+package jwt
+
+import (
+	"crypto/subtle"
+	"fmt"
+	"time"
+)
+
+// For a type to be a Claims object, it must just have a Valid method that determines
+// if the token is invalid for any supported reason
+type Claims interface {
+	Valid() error
+}
+
+// Structured version of Claims Section, as referenced at
+// https://tools.ietf.org/html/rfc7519#section-4.1
+// See examples for how to use this with your own claim types
+type StandardClaims struct {
+	Audience  string `json:"aud,omitempty"`
+	ExpiresAt int64  `json:"exp,omitempty"`
+	Id        string `json:"jti,omitempty"`
+	IssuedAt  int64  `json:"iat,omitempty"`
+	Issuer    string `json:"iss,omitempty"`
+	NotBefore int64  `json:"nbf,omitempty"`
+	Subject   string `json:"sub,omitempty"`
+}
+
+// Validates time based claims "exp, iat, nbf".
+// There is no accounting for clock skew.
+// As well, if any of the above claims are not in the token, it will still
+// be considered a valid claim.
+func (c StandardClaims) Valid() error {
+	vErr := new(ValidationError)
+	now := TimeFunc().Unix()
+
+	// The claims below are optional, by default, so if they are set to the
+	// default value in Go, let's not fail the verification for them.
+	if c.VerifyExpiresAt(now, false) == false {
+		delta := time.Unix(now, 0).Sub(time.Unix(c.ExpiresAt, 0))
+		vErr.Inner = fmt.Errorf("token is expired by %v", delta)
+		vErr.Errors |= ValidationErrorExpired
+	}
+
+	if c.VerifyIssuedAt(now, false) == false {
+		vErr.Inner = fmt.Errorf("Token used before issued")
+		vErr.Errors |= ValidationErrorIssuedAt
+	}
+
+	if c.VerifyNotBefore(now, false) == false {
+		vErr.Inner = fmt.Errorf("token is not valid yet")
+		vErr.Errors |= ValidationErrorNotValidYet
+	}
+
+	if vErr.valid() {
+		return nil
+	}
+
+	return vErr
+}
+
+// Compares the aud claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyAudience(cmp string, req bool) bool {
+	return verifyAud(c.Audience, cmp, req)
+}
+
+// Compares the exp claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyExpiresAt(cmp int64, req bool) bool {
+	return verifyExp(c.ExpiresAt, cmp, req)
+}
+
+// Compares the iat claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuedAt(cmp int64, req bool) bool {
+	return verifyIat(c.IssuedAt, cmp, req)
+}
+
+// Compares the iss claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuer(cmp string, req bool) bool {
+	return verifyIss(c.Issuer, cmp, req)
+}
+
+// Compares the nbf claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyNotBefore(cmp int64, req bool) bool {
+	return verifyNbf(c.NotBefore, cmp, req)
+}
+
+// ----- helpers
+
+func verifyAud(aud string, cmp string, required bool) bool {
+	if aud == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(aud), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyExp(exp int64, now int64, required bool) bool {
+	if exp == 0 {
+		return !required
+	}
+	return now <= exp
+}
+
+func verifyIat(iat int64, now int64, required bool) bool {
+	if iat == 0 {
+		return !required
+	}
+	return now >= iat
+}
+
+func verifyIss(iss string, cmp string, required bool) bool {
+	if iss == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(iss), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyNbf(nbf int64, now int64, required bool) bool {
+	if nbf == 0 {
+		return !required
+	}
+	return now >= nbf
+}

backend/vendor/github.com/dgrijalva/jwt-go/doc.go

@@ -0,0 +1,4 @@
+// Package jwt is a Go implementation of JSON Web Tokens: http://self-issued.info/docs/draft-jones-json-web-token.html
+//
+// See README.md for more info.
+package jwt

backend/vendor/github.com/dgrijalva/jwt-go/ecdsa.go

@@ -0,0 +1,148 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/rand"
+	"errors"
+	"math/big"
+)
+
+var (
+	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
+	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
+)
+
+// Implements the ECDSA family of signing methods signing methods
+// Expects *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for verification
+type SigningMethodECDSA struct {
+	Name      string
+	Hash      crypto.Hash
+	KeySize   int
+	CurveBits int
+}
+
+// Specific instances for EC256 and company
+var (
+	SigningMethodES256 *SigningMethodECDSA
+	SigningMethodES384 *SigningMethodECDSA
+	SigningMethodES512 *SigningMethodECDSA
+)
+
+func init() {
+	// ES256
+	SigningMethodES256 = &SigningMethodECDSA{"ES256", crypto.SHA256, 32, 256}
+	RegisterSigningMethod(SigningMethodES256.Alg(), func() SigningMethod {
+		return SigningMethodES256
+	})
+
+	// ES384
+	SigningMethodES384 = &SigningMethodECDSA{"ES384", crypto.SHA384, 48, 384}
+	RegisterSigningMethod(SigningMethodES384.Alg(), func() SigningMethod {
+		return SigningMethodES384
+	})
+
+	// ES512
+	SigningMethodES512 = &SigningMethodECDSA{"ES512", crypto.SHA512, 66, 521}
+	RegisterSigningMethod(SigningMethodES512.Alg(), func() SigningMethod {
+		return SigningMethodES512
+	})
+}
+
+func (m *SigningMethodECDSA) Alg() string {
+	return m.Name
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an ecdsa.PublicKey struct
+func (m *SigningMethodECDSA) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	// Get the key
+	var ecdsaKey *ecdsa.PublicKey
+	switch k := key.(type) {
+	case *ecdsa.PublicKey:
+		ecdsaKey = k
+	default:
+		return ErrInvalidKeyType
+	}
+
+	if len(sig) != 2*m.KeySize {
+		return ErrECDSAVerification
+	}
+
+	r := big.NewInt(0).SetBytes(sig[:m.KeySize])
+	s := big.NewInt(0).SetBytes(sig[m.KeySize:])
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	if verifystatus := ecdsa.Verify(ecdsaKey, hasher.Sum(nil), r, s); verifystatus == true {
+		return nil
+	} else {
+		return ErrECDSAVerification
+	}
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an ecdsa.PrivateKey struct
+func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string, error) {
+	// Get the key
+	var ecdsaKey *ecdsa.PrivateKey
+	switch k := key.(type) {
+	case *ecdsa.PrivateKey:
+		ecdsaKey = k
+	default:
+		return "", ErrInvalidKeyType
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return r, s
+	if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
+		curveBits := ecdsaKey.Curve.Params().BitSize
+
+		if m.CurveBits != curveBits {
+			return "", ErrInvalidKey
+		}
+
+		keyBytes := curveBits / 8
+		if curveBits%8 > 0 {
+			keyBytes += 1
+		}
+
+		// We serialize the outpus (r and s) into big-endian byte arrays and pad
+		// them with zeros on the left to make sure the sizes work out. Both arrays
+		// must be keyBytes long, and the output must be 2*keyBytes long.
+		rBytes := r.Bytes()
+		rBytesPadded := make([]byte, keyBytes)
+		copy(rBytesPadded[keyBytes-len(rBytes):], rBytes)
+
+		sBytes := s.Bytes()
+		sBytesPadded := make([]byte, keyBytes)
+		copy(sBytesPadded[keyBytes-len(sBytes):], sBytes)
+
+		out := append(rBytesPadded, sBytesPadded...)
+
+		return EncodeSegment(out), nil
+	} else {
+		return "", err
+	}
+}

backend/vendor/github.com/dgrijalva/jwt-go/ecdsa_utils.go

@@ -0,0 +1,67 @@
+package jwt
+
+import (
+	"crypto/ecdsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+)
+
+var (
+	ErrNotECPublicKey  = errors.New("Key is not a valid ECDSA public key")
+	ErrNotECPrivateKey = errors.New("Key is not a valid ECDSA private key")
+)
+
+// Parse PEM encoded Elliptic Curve Private Key Structure
+func ParseECPrivateKeyFromPEM(key []byte) (*ecdsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParseECPrivateKey(block.Bytes); err != nil {
+		return nil, err
+	}
+
+	var pkey *ecdsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PrivateKey); !ok {
+		return nil, ErrNotECPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 public key
+func ParseECPublicKeyFromPEM(key []byte) (*ecdsa.PublicKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
+		if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
+			parsedKey = cert.PublicKey
+		} else {
+			return nil, err
+		}
+	}
+
+	var pkey *ecdsa.PublicKey
+	var ok bool
+	if pkey, ok = parsedKey.(*ecdsa.PublicKey); !ok {
+		return nil, ErrNotECPublicKey
+	}
+
+	return pkey, nil
+}

backend/vendor/github.com/dgrijalva/jwt-go/errors.go

@@ -0,0 +1,59 @@
+package jwt
+
+import (
+	"errors"
+)
+
+// Error constants
+var (
+	ErrInvalidKey      = errors.New("key is invalid")
+	ErrInvalidKeyType  = errors.New("key is of invalid type")
+	ErrHashUnavailable = errors.New("the requested hash function is unavailable")
+)
+
+// The errors that might occur when parsing and validating a token
+const (
+	ValidationErrorMalformed        uint32 = 1 << iota // Token is malformed
+	ValidationErrorUnverifiable                        // Token could not be verified because of signing problems
+	ValidationErrorSignatureInvalid                    // Signature validation failed
+
+	// Standard Claim validation errors
+	ValidationErrorAudience      // AUD validation failed
+	ValidationErrorExpired       // EXP validation failed
+	ValidationErrorIssuedAt      // IAT validation failed
+	ValidationErrorIssuer        // ISS validation failed
+	ValidationErrorNotValidYet   // NBF validation failed
+	ValidationErrorId            // JTI validation failed
+	ValidationErrorClaimsInvalid // Generic claims validation error
+)
+
+// Helper for constructing a ValidationError with a string error message
+func NewValidationError(errorText string, errorFlags uint32) *ValidationError {
+	return &ValidationError{
+		text:   errorText,
+		Errors: errorFlags,
+	}
+}
+
+// The error from Parse if token is not valid
+type ValidationError struct {
+	Inner  error  // stores the error returned by external dependencies, i.e.: KeyFunc
+	Errors uint32 // bitfield.  see ValidationError... constants
+	text   string // errors that do not have a valid error just have text
+}
+
+// Validation error is an error type
+func (e ValidationError) Error() string {
+	if e.Inner != nil {
+		return e.Inner.Error()
+	} else if e.text != "" {
+		return e.text
+	} else {
+		return "token is invalid"
+	}
+}
+
+// No errors
+func (e *ValidationError) valid() bool {
+	return e.Errors == 0
+}

backend/vendor/github.com/dgrijalva/jwt-go/hmac.go

@@ -0,0 +1,95 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/hmac"
+	"errors"
+)
+
+// Implements the HMAC-SHA family of signing methods signing methods
+// Expects key type of []byte for both signing and validation
+type SigningMethodHMAC struct {
+	Name string
+	Hash crypto.Hash
+}
+
+// Specific instances for HS256 and company
+var (
+	SigningMethodHS256  *SigningMethodHMAC
+	SigningMethodHS384  *SigningMethodHMAC
+	SigningMethodHS512  *SigningMethodHMAC
+	ErrSignatureInvalid = errors.New("signature is invalid")
+)
+
+func init() {
+	// HS256
+	SigningMethodHS256 = &SigningMethodHMAC{"HS256", crypto.SHA256}
+	RegisterSigningMethod(SigningMethodHS256.Alg(), func() SigningMethod {
+		return SigningMethodHS256
+	})
+
+	// HS384
+	SigningMethodHS384 = &SigningMethodHMAC{"HS384", crypto.SHA384}
+	RegisterSigningMethod(SigningMethodHS384.Alg(), func() SigningMethod {
+		return SigningMethodHS384
+	})
+
+	// HS512
+	SigningMethodHS512 = &SigningMethodHMAC{"HS512", crypto.SHA512}
+	RegisterSigningMethod(SigningMethodHS512.Alg(), func() SigningMethod {
+		return SigningMethodHS512
+	})
+}
+
+func (m *SigningMethodHMAC) Alg() string {
+	return m.Name
+}
+
+// Verify the signature of HSXXX tokens.  Returns nil if the signature is valid.
+func (m *SigningMethodHMAC) Verify(signingString, signature string, key interface{}) error {
+	// Verify the key is the right type
+	keyBytes, ok := key.([]byte)
+	if !ok {
+		return ErrInvalidKeyType
+	}
+
+	// Decode signature, for comparison
+	sig, err := DecodeSegment(signature)
+	if err != nil {
+		return err
+	}
+
+	// Can we use the specified hashing method?
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+
+	// This signing method is symmetric, so we validate the signature
+	// by reproducing the signature from the signing string and key, then
+	// comparing that against the provided signature.
+	hasher := hmac.New(m.Hash.New, keyBytes)
+	hasher.Write([]byte(signingString))
+	if !hmac.Equal(sig, hasher.Sum(nil)) {
+		return ErrSignatureInvalid
+	}
+
+	// No validation errors.  Signature is good.
+	return nil
+}
+
+// Implements the Sign method from SigningMethod for this signing method.
+// Key must be []byte
+func (m *SigningMethodHMAC) Sign(signingString string, key interface{}) (string, error) {
+	if keyBytes, ok := key.([]byte); ok {
+		if !m.Hash.Available() {
+			return "", ErrHashUnavailable
+		}
+
+		hasher := hmac.New(m.Hash.New, keyBytes)
+		hasher.Write([]byte(signingString))
+
+		return EncodeSegment(hasher.Sum(nil)), nil
+	}
+
+	return "", ErrInvalidKeyType
+}

backend/vendor/github.com/dgrijalva/jwt-go/map_claims.go

@@ -0,0 +1,94 @@
+package jwt
+
+import (
+	"encoding/json"
+	"errors"
+	// "fmt"
+)
+
+// Claims type that uses the map[string]interface{} for JSON decoding
+// This is the default claims type if you don't supply one
+type MapClaims map[string]interface{}
+
+// Compares the aud claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyAudience(cmp string, req bool) bool {
+	aud, _ := m["aud"].(string)
+	return verifyAud(aud, cmp, req)
+}
+
+// Compares the exp claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyExpiresAt(cmp int64, req bool) bool {
+	switch exp := m["exp"].(type) {
+	case float64:
+		return verifyExp(int64(exp), cmp, req)
+	case json.Number:
+		v, _ := exp.Int64()
+		return verifyExp(v, cmp, req)
+	}
+	return req == false
+}
+
+// Compares the iat claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyIssuedAt(cmp int64, req bool) bool {
+	switch iat := m["iat"].(type) {
+	case float64:
+		return verifyIat(int64(iat), cmp, req)
+	case json.Number:
+		v, _ := iat.Int64()
+		return verifyIat(v, cmp, req)
+	}
+	return req == false
+}
+
+// Compares the iss claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyIssuer(cmp string, req bool) bool {
+	iss, _ := m["iss"].(string)
+	return verifyIss(iss, cmp, req)
+}
+
+// Compares the nbf claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (m MapClaims) VerifyNotBefore(cmp int64, req bool) bool {
+	switch nbf := m["nbf"].(type) {
+	case float64:
+		return verifyNbf(int64(nbf), cmp, req)
+	case json.Number:
+		v, _ := nbf.Int64()
+		return verifyNbf(v, cmp, req)
+	}
+	return req == false
+}
+
+// Validates time based claims "exp, iat, nbf".
+// There is no accounting for clock skew.
+// As well, if any of the above claims are not in the token, it will still
+// be considered a valid claim.
+func (m MapClaims) Valid() error {
+	vErr := new(ValidationError)
+	now := TimeFunc().Unix()
+
+	if m.VerifyExpiresAt(now, false) == false {
+		vErr.Inner = errors.New("Token is expired")
+		vErr.Errors |= ValidationErrorExpired
+	}
+
+	if m.VerifyIssuedAt(now, false) == false {
+		vErr.Inner = errors.New("Token used before issued")
+		vErr.Errors |= ValidationErrorIssuedAt
+	}
+
+	if m.VerifyNotBefore(now, false) == false {
+		vErr.Inner = errors.New("Token is not valid yet")
+		vErr.Errors |= ValidationErrorNotValidYet
+	}
+
+	if vErr.valid() {
+		return nil
+	}
+
+	return vErr
+}

backend/vendor/github.com/dgrijalva/jwt-go/none.go

@@ -0,0 +1,52 @@
+package jwt
+
+// Implements the none signing method.  This is required by the spec
+// but you probably should never use it.
+var SigningMethodNone *signingMethodNone
+
+const UnsafeAllowNoneSignatureType unsafeNoneMagicConstant = "none signing method allowed"
+
+var NoneSignatureTypeDisallowedError error
+
+type signingMethodNone struct{}
+type unsafeNoneMagicConstant string
+
+func init() {
+	SigningMethodNone = &signingMethodNone{}
+	NoneSignatureTypeDisallowedError = NewValidationError("'none' signature type is not allowed", ValidationErrorSignatureInvalid)
+
+	RegisterSigningMethod(SigningMethodNone.Alg(), func() SigningMethod {
+		return SigningMethodNone
+	})
+}
+
+func (m *signingMethodNone) Alg() string {
+	return "none"
+}
+
+// Only allow 'none' alg type if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Verify(signingString, signature string, key interface{}) (err error) {
+	// Key must be UnsafeAllowNoneSignatureType to prevent accidentally
+	// accepting 'none' signing method
+	if _, ok := key.(unsafeNoneMagicConstant); !ok {
+		return NoneSignatureTypeDisallowedError
+	}
+	// If signing method is none, signature must be an empty string
+	if signature != "" {
+		return NewValidationError(
+			"'none' signing method with non-empty signature",
+			ValidationErrorSignatureInvalid,
+		)
+	}
+
+	// Accept 'none' signing method.
+	return nil
+}
+
+// Only allow 'none' signing if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Sign(signingString string, key interface{}) (string, error) {
+	if _, ok := key.(unsafeNoneMagicConstant); ok {
+		return "", nil
+	}
+	return "", NoneSignatureTypeDisallowedError
+}

backend/vendor/github.com/dgrijalva/jwt-go/parser.go

@@ -0,0 +1,148 @@
+package jwt
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+type Parser struct {
+	ValidMethods         []string // If populated, only these methods will be considered valid
+	UseJSONNumber        bool     // Use JSON Number format in JSON decoder
+	SkipClaimsValidation bool     // Skip claims validation during token parsing
+}
+
+// Parse, validate, and return a token.
+// keyFunc will receive the parsed token and should return the key for validating.
+// If everything is kosher, err will be nil
+func (p *Parser) Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
+	return p.ParseWithClaims(tokenString, MapClaims{}, keyFunc)
+}
+
+func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
+	token, parts, err := p.ParseUnverified(tokenString, claims)
+	if err != nil {
+		return token, err
+	}
+
+	// Verify signing method is in the required set
+	if p.ValidMethods != nil {
+		var signingMethodValid = false
+		var alg = token.Method.Alg()
+		for _, m := range p.ValidMethods {
+			if m == alg {
+				signingMethodValid = true
+				break
+			}
+		}
+		if !signingMethodValid {
+			// signing method is not in the listed set
+			return token, NewValidationError(fmt.Sprintf("signing method %v is invalid", alg), ValidationErrorSignatureInvalid)
+		}
+	}
+
+	// Lookup key
+	var key interface{}
+	if keyFunc == nil {
+		// keyFunc was not provided.  short circuiting validation
+		return token, NewValidationError("no Keyfunc was provided.", ValidationErrorUnverifiable)
+	}
+	if key, err = keyFunc(token); err != nil {
+		// keyFunc returned an error
+		if ve, ok := err.(*ValidationError); ok {
+			return token, ve
+		}
+		return token, &ValidationError{Inner: err, Errors: ValidationErrorUnverifiable}
+	}
+
+	vErr := &ValidationError{}
+
+	// Validate Claims
+	if !p.SkipClaimsValidation {
+		if err := token.Claims.Valid(); err != nil {
+
+			// If the Claims Valid returned an error, check if it is a validation error,
+			// If it was another error type, create a ValidationError with a generic ClaimsInvalid flag set
+			if e, ok := err.(*ValidationError); !ok {
+				vErr = &ValidationError{Inner: err, Errors: ValidationErrorClaimsInvalid}
+			} else {
+				vErr = e
+			}
+		}
+	}
+
+	// Perform validation
+	token.Signature = parts[2]
+	if err = token.Method.Verify(strings.Join(parts[0:2], "."), token.Signature, key); err != nil {
+		vErr.Inner = err
+		vErr.Errors |= ValidationErrorSignatureInvalid
+	}
+
+	if vErr.valid() {
+		token.Valid = true
+		return token, nil
+	}
+
+	return token, vErr
+}
+
+// WARNING: Don't use this method unless you know what you're doing
+//
+// This method parses the token but doesn't validate the signature. It's only
+// ever useful in cases where you know the signature is valid (because it has
+// been checked previously in the stack) and you want to extract values from
+// it.
+func (p *Parser) ParseUnverified(tokenString string, claims Claims) (token *Token, parts []string, err error) {
+	parts = strings.Split(tokenString, ".")
+	if len(parts) != 3 {
+		return nil, parts, NewValidationError("token contains an invalid number of segments", ValidationErrorMalformed)
+	}
+
+	token = &Token{Raw: tokenString}
+
+	// parse Header
+	var headerBytes []byte
+	if headerBytes, err = DecodeSegment(parts[0]); err != nil {
+		if strings.HasPrefix(strings.ToLower(tokenString), "bearer ") {
+			return token, parts, NewValidationError("tokenstring should not contain 'bearer '", ValidationErrorMalformed)
+		}
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	if err = json.Unmarshal(headerBytes, &token.Header); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// parse Claims
+	var claimBytes []byte
+	token.Claims = claims
+
+	if claimBytes, err = DecodeSegment(parts[1]); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
+	if p.UseJSONNumber {
+		dec.UseNumber()
+	}
+	// JSON Decode.  Special case for map type to avoid weird pointer behavior
+	if c, ok := token.Claims.(MapClaims); ok {
+		err = dec.Decode(&c)
+	} else {
+		err = dec.Decode(&claims)
+	}
+	// Handle decode error
+	if err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// Lookup signature method
+	if method, ok := token.Header["alg"].(string); ok {
+		if token.Method = GetSigningMethod(method); token.Method == nil {
+			return token, parts, NewValidationError("signing method (alg) is unavailable.", ValidationErrorUnverifiable)
+		}
+	} else {
+		return token, parts, NewValidationError("signing method (alg) is unspecified.", ValidationErrorUnverifiable)
+	}
+
+	return token, parts, nil
+}

backend/vendor/github.com/dgrijalva/jwt-go/rsa.go

@@ -0,0 +1,101 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+// Implements the RSA family of signing methods signing methods
+// Expects *rsa.PrivateKey for signing and *rsa.PublicKey for validation
+type SigningMethodRSA struct {
+	Name string
+	Hash crypto.Hash
+}
+
+// Specific instances for RS256 and company
+var (
+	SigningMethodRS256 *SigningMethodRSA
+	SigningMethodRS384 *SigningMethodRSA
+	SigningMethodRS512 *SigningMethodRSA
+)
+
+func init() {
+	// RS256
+	SigningMethodRS256 = &SigningMethodRSA{"RS256", crypto.SHA256}
+	RegisterSigningMethod(SigningMethodRS256.Alg(), func() SigningMethod {
+		return SigningMethodRS256
+	})
+
+	// RS384
+	SigningMethodRS384 = &SigningMethodRSA{"RS384", crypto.SHA384}
+	RegisterSigningMethod(SigningMethodRS384.Alg(), func() SigningMethod {
+		return SigningMethodRS384
+	})
+
+	// RS512
+	SigningMethodRS512 = &SigningMethodRSA{"RS512", crypto.SHA512}
+	RegisterSigningMethod(SigningMethodRS512.Alg(), func() SigningMethod {
+		return SigningMethodRS512
+	})
+}
+
+func (m *SigningMethodRSA) Alg() string {
+	return m.Name
+}
+
+// Implements the Verify method from SigningMethod
+// For this signing method, must be an *rsa.PublicKey structure.
+func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	var rsaKey *rsa.PublicKey
+	var ok bool
+
+	if rsaKey, ok = key.(*rsa.PublicKey); !ok {
+		return ErrInvalidKeyType
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, must be an *rsa.PrivateKey structure.
+func (m *SigningMethodRSA) Sign(signingString string, key interface{}) (string, error) {
+	var rsaKey *rsa.PrivateKey
+	var ok bool
+
+	// Validate type of key
+	if rsaKey, ok = key.(*rsa.PrivateKey); !ok {
+		return "", ErrInvalidKey
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return the encoded bytes
+	if sigBytes, err := rsa.SignPKCS1v15(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil)); err == nil {
+		return EncodeSegment(sigBytes), nil
+	} else {
+		return "", err
+	}
+}

backend/vendor/github.com/dgrijalva/jwt-go/rsa_pss.go

@@ -0,0 +1,126 @@
+// +build go1.4
+
+package jwt
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+)
+
+// Implements the RSAPSS family of signing methods signing methods
+type SigningMethodRSAPSS struct {
+	*SigningMethodRSA
+	Options *rsa.PSSOptions
+}
+
+// Specific instances for RS/PS and company
+var (
+	SigningMethodPS256 *SigningMethodRSAPSS
+	SigningMethodPS384 *SigningMethodRSAPSS
+	SigningMethodPS512 *SigningMethodRSAPSS
+)
+
+func init() {
+	// PS256
+	SigningMethodPS256 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS256",
+			Hash: crypto.SHA256,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA256,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS256.Alg(), func() SigningMethod {
+		return SigningMethodPS256
+	})
+
+	// PS384
+	SigningMethodPS384 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS384",
+			Hash: crypto.SHA384,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA384,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS384.Alg(), func() SigningMethod {
+		return SigningMethodPS384
+	})
+
+	// PS512
+	SigningMethodPS512 = &SigningMethodRSAPSS{
+		&SigningMethodRSA{
+			Name: "PS512",
+			Hash: crypto.SHA512,
+		},
+		&rsa.PSSOptions{
+			SaltLength: rsa.PSSSaltLengthAuto,
+			Hash:       crypto.SHA512,
+		},
+	}
+	RegisterSigningMethod(SigningMethodPS512.Alg(), func() SigningMethod {
+		return SigningMethodPS512
+	})
+}
+
+// Implements the Verify method from SigningMethod
+// For this verify method, key must be an rsa.PublicKey struct
+func (m *SigningMethodRSAPSS) Verify(signingString, signature string, key interface{}) error {
+	var err error
+
+	// Decode the signature
+	var sig []byte
+	if sig, err = DecodeSegment(signature); err != nil {
+		return err
+	}
+
+	var rsaKey *rsa.PublicKey
+	switch k := key.(type) {
+	case *rsa.PublicKey:
+		rsaKey = k
+	default:
+		return ErrInvalidKey
+	}
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	return rsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, m.Options)
+}
+
+// Implements the Sign method from SigningMethod
+// For this signing method, key must be an rsa.PrivateKey struct
+func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (string, error) {
+	var rsaKey *rsa.PrivateKey
+
+	switch k := key.(type) {
+	case *rsa.PrivateKey:
+		rsaKey = k
+	default:
+		return "", ErrInvalidKeyType
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return "", ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return the encoded bytes
+	if sigBytes, err := rsa.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); err == nil {
+		return EncodeSegment(sigBytes), nil
+	} else {
+		return "", err
+	}
+}

backend/vendor/github.com/dgrijalva/jwt-go/rsa_utils.go

@@ -0,0 +1,101 @@
+package jwt
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+)
+
+var (
+	ErrKeyMustBePEMEncoded = errors.New("Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key")
+	ErrNotRSAPrivateKey    = errors.New("Key is not a valid RSA private key")
+	ErrNotRSAPublicKey     = errors.New("Key is not a valid RSA public key")
+)
+
+// Parse PEM encoded PKCS1 or PKCS8 private key
+func ParseRSAPrivateKeyFromPEM(key []byte) (*rsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKCS1PrivateKey(block.Bytes); err != nil {
+		if parsedKey, err = x509.ParsePKCS8PrivateKey(block.Bytes); err != nil {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
+		return nil, ErrNotRSAPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 private key protected with password
+func ParseRSAPrivateKeyFromPEMWithPassword(key []byte, password string) (*rsa.PrivateKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	var parsedKey interface{}
+
+	var blockDecrypted []byte
+	if blockDecrypted, err = x509.DecryptPEMBlock(block, []byte(password)); err != nil {
+		return nil, err
+	}
+
+	if parsedKey, err = x509.ParsePKCS1PrivateKey(blockDecrypted); err != nil {
+		if parsedKey, err = x509.ParsePKCS8PrivateKey(blockDecrypted); err != nil {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PrivateKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
+		return nil, ErrNotRSAPrivateKey
+	}
+
+	return pkey, nil
+}
+
+// Parse PEM encoded PKCS1 or PKCS8 public key
+func ParseRSAPublicKeyFromPEM(key []byte) (*rsa.PublicKey, error) {
+	var err error
+
+	// Parse PEM block
+	var block *pem.Block
+	if block, _ = pem.Decode(key); block == nil {
+		return nil, ErrKeyMustBePEMEncoded
+	}
+
+	// Parse the key
+	var parsedKey interface{}
+	if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
+		if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
+			parsedKey = cert.PublicKey
+		} else {
+			return nil, err
+		}
+	}
+
+	var pkey *rsa.PublicKey
+	var ok bool
+	if pkey, ok = parsedKey.(*rsa.PublicKey); !ok {
+		return nil, ErrNotRSAPublicKey
+	}
+
+	return pkey, nil
+}

backend/vendor/github.com/dgrijalva/jwt-go/signing_method.go

@@ -0,0 +1,35 @@
+package jwt
+
+import (
+	"sync"
+)
+
+var signingMethods = map[string]func() SigningMethod{}
+var signingMethodLock = new(sync.RWMutex)
+
+// Implement SigningMethod to add new methods for signing or verifying tokens.
+type SigningMethod interface {
+	Verify(signingString, signature string, key interface{}) error // Returns nil if signature is valid
+	Sign(signingString string, key interface{}) (string, error)    // Returns encoded signature or error
+	Alg() string                                                   // returns the alg identifier for this method (example: 'HS256')
+}
+
+// Register the "alg" name and a factory function for signing method.
+// This is typically done during init() in the method's implementation
+func RegisterSigningMethod(alg string, f func() SigningMethod) {
+	signingMethodLock.Lock()
+	defer signingMethodLock.Unlock()
+
+	signingMethods[alg] = f
+}
+
+// Get a signing method from an "alg" string
+func GetSigningMethod(alg string) (method SigningMethod) {
+	signingMethodLock.RLock()
+	defer signingMethodLock.RUnlock()
+
+	if methodF, ok := signingMethods[alg]; ok {
+		method = methodF()
+	}
+	return
+}

backend/vendor/github.com/dgrijalva/jwt-go/token.go

@@ -0,0 +1,108 @@
+package jwt
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+// TimeFunc provides the current time when parsing token to validate "exp" claim (expiration time).
+// You can override it to use another time value.  This is useful for testing or if your
+// server uses a different time zone than your tokens.
+var TimeFunc = time.Now
+
+// Parse methods use this callback function to supply
+// the key for verification.  The function receives the parsed,
+// but unverified Token.  This allows you to use properties in the
+// Header of the token (such as `kid`) to identify which key to use.
+type Keyfunc func(*Token) (interface{}, error)
+
+// A JWT Token.  Different fields will be used depending on whether you're
+// creating or parsing/verifying a token.
+type Token struct {
+	Raw       string                 // The raw token.  Populated when you Parse a token
+	Method    SigningMethod          // The signing method used or to be used
+	Header    map[string]interface{} // The first segment of the token
+	Claims    Claims                 // The second segment of the token
+	Signature string                 // The third segment of the token.  Populated when you Parse a token
+	Valid     bool                   // Is the token valid?  Populated when you Parse/Verify a token
+}
+
+// Create a new Token.  Takes a signing method
+func New(method SigningMethod) *Token {
+	return NewWithClaims(method, MapClaims{})
+}
+
+func NewWithClaims(method SigningMethod, claims Claims) *Token {
+	return &Token{
+		Header: map[string]interface{}{
+			"typ": "JWT",
+			"alg": method.Alg(),
+		},
+		Claims: claims,
+		Method: method,
+	}
+}
+
+// Get the complete, signed token
+func (t *Token) SignedString(key interface{}) (string, error) {
+	var sig, sstr string
+	var err error
+	if sstr, err = t.SigningString(); err != nil {
+		return "", err
+	}
+	if sig, err = t.Method.Sign(sstr, key); err != nil {
+		return "", err
+	}
+	return strings.Join([]string{sstr, sig}, "."), nil
+}
+
+// Generate the signing string.  This is the
+// most expensive part of the whole deal.  Unless you
+// need this for something special, just go straight for
+// the SignedString.
+func (t *Token) SigningString() (string, error) {
+	var err error
+	parts := make([]string, 2)
+	for i, _ := range parts {
+		var jsonValue []byte
+		if i == 0 {
+			if jsonValue, err = json.Marshal(t.Header); err != nil {
+				return "", err
+			}
+		} else {
+			if jsonValue, err = json.Marshal(t.Claims); err != nil {
+				return "", err
+			}
+		}
+
+		parts[i] = EncodeSegment(jsonValue)
+	}
+	return strings.Join(parts, "."), nil
+}
+
+// Parse, validate, and return a token.
+// keyFunc will receive the parsed token and should return the key for validating.
+// If everything is kosher, err will be nil
+func Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
+	return new(Parser).Parse(tokenString, keyFunc)
+}
+
+func ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
+	return new(Parser).ParseWithClaims(tokenString, claims, keyFunc)
+}
+
+// Encode JWT specific base64url encoding with padding stripped
+func EncodeSegment(seg []byte) string {
+	return strings.TrimRight(base64.URLEncoding.EncodeToString(seg), "=")
+}
+
+// Decode JWT specific base64url encoding with padding stripped
+func DecodeSegment(seg string) ([]byte, error) {
+	if l := len(seg) % 4; l > 0 {
+		seg += strings.Repeat("=", 4-l)
+	}
+
+	return base64.URLEncoding.DecodeString(seg)
+}

backend/vendor/github.com/go-pkgz/auth/.gitignore

@@ -0,0 +1,14 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+.vscode
+*.cov

backend/vendor/github.com/go-pkgz/auth/.travis.yml

@@ -0,0 +1,23 @@
+language: go
+
+services:
+  - mongodb
+
+go:
+  - "1.11.x"
+
+install: true
+
+before_install:
+  - export TZ=America/Chicago
+  - curl -L https://git.io/vp6lP | sh 
+  - go get github.com/mattn/goveralls
+  - export MONGO_TEST=mongodb://127.0.0.1:27017
+  - export PATH=$(pwd)/bin:$PATH
+
+script:
+  - GO111MODULE=on go get ./...
+  - GO111MODULE=on go mod vendor
+  - GO111MODULE=on go test  -v -mod=vendor -covermode=count -coverprofile=profile.cov ./... || travis_terminate 1;
+  - ./bin/gometalinter --deadline=120s --exclude=test --exclude=mock --exclude=vendor --disable-all --enable=errcheck --enable=vet --enable=vetshadow --enable=megacheck --enable=ineffassign --enable=varcheck --enable=unconvert --enable=deadcode --enable=interfacer --enable=gotype ./... || travis_terminate 1;
+  - $GOPATH/bin/goveralls -coverprofile=profile.cov -service=travis-ci

backend/vendor/github.com/go-pkgz/auth/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 Umputun
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

backend/vendor/github.com/go-pkgz/auth/README.md

@@ -0,0 +1,128 @@
+# auth - authentication via oauth2 [![Build Status](https://travis-ci.org/go-pkgz/auth.svg?branch=master)](https://travis-ci.org/go-pkgz/auth) [![Coverage Status](https://coveralls.io/repos/github/go-pkgz/auth/badge.svg?branch=master)](https://coveralls.io/github/go-pkgz/auth?branch=master)
+
+This library provides "social login" with Github, Google, Facebook and Yandex.  
+
+- Multiple oauth2 providers can be used at the same time
+- Special `dev` provider allows local testing and development
+- JWT stored in a secure cookie and with XSRF protection. Cookies can be session-only
+- Minimal scopes with user name, id and picture (avatar) only
+- Integrated avatar proxy with FS, boltdb or gridfs storage
+- Support of user-defined storages
+- Black list with user-defined validator
+- Multiple aud (audience) supported
+- Secure key with customizable `SecretReader`
+- Ability to store extra information to token and retrieve on login
+- Middleware for easy integration into http routers
+
+## Install
+
+`go install github.com/go-pkgz/auth`
+
+## Usage
+
+Example with chi router:
+
+```go
+func main() {
+	/// define options
+	options := auth.Opts{
+		SecretReader:   token.SecretFunc(func(id string) (string, error) { return "secret", nil }), // secret key for JWT
+		TokenDuration:  time.Hour,
+		CookieDuration: time.Hour * 24,
+		Issuer:         "my-test-app",
+		URL:            "http://127.0.0.1:8080",
+		AvatarStore:    avatar.NewLocalFS("/tmp", 120),
+		Validator: middleware.ValidatorFunc(func(_ string, claims token.Claims) bool {
+			return claims.User != nil && strings.HasPrefix(claims.User.Name, "dev_") // allow only dev_ names
+		}),		
+	}
+
+	// create auth service
+	service, err := auth.NewService(options)
+	if err != nil {
+		log.Fatal(err)
+	}
+	service.AddProvider("github", "<Client ID>", "<Client Secret>")   // add github provider
+	service.AddProvider("facebook", "<Client ID>", "<Client Secret>") // add facebook provider
+
+	// retrieve auth middleware
+	m := service.Middleware()
+
+	// setup http server
+	router := chi.NewRouter()
+	router.Get("/open", openRouteHandler)                      // open api
+	router.With(m.Auth).Get("/private", protectedRouteHandler) // protected api
+
+	// setup auth routes
+	authRoutes, avaRoutes := service.Handlers()
+	router.Mount("/auth", authRoutes)  // add auth handlers
+	router.Mount("/avatar", avaRoutes) // add avatar handler
+
+	log.Fatal(http.ListenAndServe(":8080", router))
+}
+```
+
+## Middleware
+
+`github.com/go-pkgz/auth/middleware` provides ready-to-use middleware.
+
+- `middleware.Auth` - requires authenticated user
+- `middleware.Admin` - requires authenticated and admin user
+- `middleware.Trace` - doesn't require authenticated user, but adds user info to request
+  
+## Register oauth2 providers
+
+Authentication handled by external providers. You should setup oauth2 for all (or some) of them to allow users to authenticate. It is not mandatory to have all of them, but at least one should be correctly configured.
+
+#### Google Auth Provider
+
+1.  Create a new project: https://console.developers.google.com/project
+1.  Choose the new project from the top right project dropdown (only if another project is selected)
+1.  In the project Dashboard center pane, choose **"API Manager"**
+1.  In the left Nav pane, choose **"Credentials"**
+1.  In the center pane, choose **"OAuth consent screen"** tab. Fill in **"Product name shown to users"** and hit save.
+1.  In the center pane, choose **"Credentials"** tab.
+    * Open the **"New credentials"** drop down
+    * Choose **"OAuth client ID"**
+    * Choose **"Web application"**
+    * Application name is freeform, choose something appropriate
+    * Authorized origins is your domain ex: `https://example.mysite.com`
+    * Authorized redirect URIs is the location of oauth2/callback constructed as domain + `/auth/google/callback`, ex: `https://example.mysite.com/auth/google/callback`
+    * Choose **"Create"**
+2.  Take note of the **Client ID** and **Client Secret**
+
+_instructions for google oauth2 setup borrowed from [oauth2_proxy](https://github.com/bitly/oauth2_proxy)_
+
+#### GitHub Auth Provider
+
+1.  Create a new **"OAuth App"**: https://github.com/settings/developers
+1.  Fill **"Application Name"** and **"Homepage URL"** for your site
+1.  Under **"Authorization callback URL"** enter the correct url constructed as domain + `/auth/github/callback`. ie `https://example.mysite.com/auth/github/callback`
+1.  Take note of the **Client ID** and **Client Secret**
+
+#### Facebook Auth Provider
+
+1.  From https://developers.facebook.com select **"My Apps"** / **"Add a new App"**
+1.  Set **"Display Name"** and **"Contact email"**
+1.  Choose **"Facebook Login"** and then **"Web"**
+1.  Set "Site URL" to your domain, ex: `https://example.mysite.com`
+1.  Under **"Facebook login"** / **"Settings"** fill "Valid OAuth redirect URIs" with your callback url constructed as domain + `/auth/facebook/callback`
+1.  Select **"App Review"** and turn public flag on. This step may ask you to provide a link to your privacy policy.
+
+#### Yandex Auth Provider
+
+1.  Create a new **"OAuth App"**: https://oauth.yandex.com/client/new
+1.  Fill **"App name"** for your site
+1.  Under **Platforms** select **"Web services"** and enter **"Callback URI #1"** constructed as domain + `/auth/yandex/callback`. ie `https://example.mysite.com/auth/yandex/callback`
+1.  Select **Permissions**. You need following permissions only from the **"Yandex.Passport API"** section:
+    * Access to user avatar
+    * Access to username, first name and surname, gender
+1.  Fill out the rest of fields if needed
+1.  Take note of the **ID** and **Password**
+
+For more details refer to [Yandex OAuth](https://tech.yandex.com/oauth/doc/dg/concepts/about-docpage/) and [Yandex.Passport](https://tech.yandex.com/passport/doc/dg/index-docpage/) API documentation.
+
+
+## Status 
+
+The library extracted from [remark42](https://github.com/umputun/remark) project. The code in production use on multiple sites and seems to work fine.

backend/vendor/github.com/go-pkgz/auth/auth.go

@@ -0,0 +1,201 @@
+package auth
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/go-pkgz/rest"
+	"github.com/pkg/errors"
+
+	"github.com/go-pkgz/auth/avatar"
+	"github.com/go-pkgz/auth/middleware"
+	"github.com/go-pkgz/auth/provider"
+	"github.com/go-pkgz/auth/token"
+)
+
+// Service provides higher level wrapper allowing to construct everything and get back token middleware
+type Service struct {
+	opts           Opts
+	jwtService     *token.Service
+	providers      []provider.Service
+	authMiddleware middleware.Authenticator
+	avatarProxy    *avatar.Proxy
+	issuer         string
+}
+
+// Opts is a full set of all parameters to initialize Service
+type Opts struct {
+	SecretReader   token.Secret        // reader returns secret for given site id (aud)
+	ClaimsUpd      token.ClaimsUpdater // updater for jwt to add/modify values stored in the token
+	SecureCookies  bool                // makes jwt cookie secure
+	TokenDuration  time.Duration       // token's TTL, refreshed automatically
+	CookieDuration time.Duration       // cookie's TTL. This cookie stores JWT token
+	DisableXSRF    bool                // disable XSRF protection, useful for testing/debugging
+
+	// optional (custom) names for cookies and headers
+	JWTCookieName  string // default "JWT"
+	JWTHeaderKey   string // default "X-JWT"
+	XSRFCookieName string // default "XSRF-TOKEN"
+	XSRFHeaderKey  string // default "X-XSRF-TOKEN"
+
+	Issuer string // optional value for iss claim, usually the application name, default "go-pkgz/auth"
+
+	URL       string          // root url for the rest service, i.e. http://blah.example.com
+	Validator token.Validator // validator allows to reject some valid tokens with user-defined logic
+
+	AvatarStore       avatar.Store // store to save/load avatars
+	AvatarResizeLimit int          // resize avatar's limit in pixels
+	AvatarRoutePath   string       // avatar routing prefix, i.e. "/api/v1/avatar"
+
+	DevPasswd string // if presented, allows basic auth with user dev and given password
+}
+
+// NewService initializes everything
+func NewService(opts Opts) *Service {
+
+	jwtService := token.NewService(token.Opts{
+		SecretReader:   opts.SecretReader,
+		ClaimsUpd:      opts.ClaimsUpd,
+		SecureCookies:  opts.SecureCookies,
+		TokenDuration:  opts.TokenDuration,
+		CookieDuration: opts.CookieDuration,
+		DisableXSRF:    opts.DisableXSRF,
+		JWTCookieName:  opts.JWTCookieName,
+		JWTHeaderKey:   opts.JWTHeaderKey,
+		XSRFCookieName: opts.XSRFCookieName,
+		XSRFHeaderKey:  opts.XSRFHeaderKey,
+		Issuer:         opts.Issuer,
+	})
+
+	if opts.SecretReader == nil {
+		jwtService.SecretReader = token.SecretFunc(func(id string) (string, error) {
+			return "", errors.New("secrets reader not avalibale")
+		})
+	}
+
+	res := Service{
+		opts:       opts,
+		jwtService: jwtService,
+		authMiddleware: middleware.Authenticator{
+			JWTService: jwtService,
+			Validator:  opts.Validator,
+			DevPasswd:  opts.DevPasswd,
+		},
+	}
+
+	if opts.Issuer == "" {
+		res.issuer = "go-pkgz/auth"
+	}
+
+	if opts.AvatarStore != nil {
+		res.avatarProxy = &avatar.Proxy{
+			Store:       opts.AvatarStore,
+			URL:         opts.URL,
+			RoutePath:   opts.AvatarRoutePath,
+			ResizeLimit: opts.AvatarResizeLimit,
+		}
+	}
+
+	return &res
+}
+
+// Handlers gets http.Handler for all providers and avatars
+func (s *Service) Handlers() (authHandler http.Handler, avatarHandler http.Handler) {
+
+	providerHandler := func(w http.ResponseWriter, r *http.Request) {
+		elems := strings.Split(r.URL.Path, "/")
+		if len(elems) < 2 {
+			w.WriteHeader(http.StatusBadRequest)
+			return
+		}
+
+		// list all providers
+		if elems[len(elems)-1] == "list" {
+			list := []string{}
+			for _, p := range s.providers {
+				list = append(list, p.Name)
+			}
+			rest.RenderJSON(w, r, list)
+			return
+		}
+
+		// allow logout without specifying provider
+		if elems[len(elems)-1] == "logout" {
+			s.providers[0].Handler(w, r)
+			return
+		}
+
+		provName := elems[len(elems)-2]
+		p, err := s.Provider(provName)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			rest.RenderJSON(w, r, rest.JSON{"error": fmt.Sprintf("provider %s not supported", provName)})
+			return
+		}
+		p.Handler(w, r)
+	}
+
+	return http.HandlerFunc(providerHandler), http.HandlerFunc(s.avatarProxy.Handler)
+}
+
+// Middleware returns token middleware
+func (s *Service) Middleware() middleware.Authenticator {
+	return s.authMiddleware
+}
+
+// AddProvider adds provider for given name
+func (s *Service) AddProvider(name string, cid string, csecret string) {
+
+	p := provider.Params{
+		URL:         s.opts.URL,
+		JwtService:  s.jwtService,
+		Issuer:      s.issuer,
+		AvatarProxy: s.avatarProxy,
+		Cid:         cid,
+		Csecret:     csecret,
+	}
+
+	switch strings.ToLower(name) {
+	case "github":
+		s.providers = append(s.providers, provider.NewGithub(p))
+	case "google":
+		s.providers = append(s.providers, provider.NewGoogle(p))
+	case "facebook":
+		s.providers = append(s.providers, provider.NewFacebook(p))
+	case "yandex":
+		s.providers = append(s.providers, provider.NewFacebook(p))
+	case "dev":
+		s.providers = append(s.providers, provider.NewDev(p))
+	default:
+		return
+	}
+
+	s.authMiddleware.Providers = s.providers
+}
+
+// Provider gets provider by name
+func (s *Service) Provider(name string) (provider.Service, error) {
+	for _, p := range s.providers {
+		if p.Name == name {
+			return p, nil
+		}
+	}
+	return provider.Service{}, errors.Errorf("provider %s not found", name)
+}
+
+// Providers gets all registered providers
+func (s *Service) Providers() []provider.Service {
+	return s.providers
+}
+
+// TokenService returns token.Service
+func (s *Service) TokenService() *token.Service {
+	return s.jwtService
+}
+
+// AvatarProxy returns stored in service
+func (s *Service) AvatarProxy() *avatar.Proxy {
+	return s.avatarProxy
+}

backend/vendor/github.com/go-pkgz/auth/avatar/avatar.go

@@ -0,0 +1,162 @@
+// Package avatar implements avatart proxy for oauth and
+// defines store interface and implements local (fs), gridfs (mongo) and boltdb stores.
+package avatar
+
+import (
+	"bytes"
+	"image"
+	"image/png"
+	"io"
+	"log"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-pkgz/rest"
+	"github.com/pkg/errors"
+	"golang.org/x/image/draw"
+
+	"github.com/go-pkgz/auth/token"
+)
+
+// Proxy provides http handler for avatars from avatar.Store
+// On user login token will call Put and it will retrieve and save picture locally.
+type Proxy struct {
+	Store       Store
+	RoutePath   string
+	URL         string
+	ResizeLimit int
+}
+
+// Put stores retrieved avatar to avatar.Store. Gets image from user info. Returns proxied url
+func (p *Proxy) Put(u token.User) (avatarURL string, err error) {
+
+	// no picture for user, try default avatar
+	if u.Picture == "" {
+		return "", errors.Errorf("no picture for %s", u.ID)
+	}
+
+	// load avatar from remote location
+	client := http.Client{Timeout: 10 * time.Second}
+	var resp *http.Response
+	err = retry(5, time.Second, func() error {
+		var e error
+		resp, e = client.Get(u.Picture)
+		return e
+	})
+	if err != nil {
+		return "", errors.Wrap(err, "failed to fetch avatar from the orig")
+	}
+
+	defer func() {
+		if e := resp.Body.Close(); e != nil {
+			log.Printf("[WARN] can't close response body, %s", e)
+		}
+	}()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", errors.Errorf("failed to get avatar from the orig, status %s", resp.Status)
+	}
+
+	avatarID, err := p.Store.Put(u.ID, p.resize(resp.Body, p.ResizeLimit)) // put returns avatar base name, like 123456.image
+	if err != nil {
+		return "", err
+	}
+
+	log.Printf("[DEBUG] saved avatar from %s to %s, user %q", u.Picture, avatarID, u.Name)
+	return p.URL + p.RoutePath + "/" + avatarID, nil
+}
+
+// Handler returns token routes for given provider
+func (p *Proxy) Handler(w http.ResponseWriter, r *http.Request) {
+
+	if r.Method != "GET" {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+	}
+	elems := strings.Split(r.URL.Path, "/")
+	avatarID := elems[len(elems)-1]
+
+	// enforce client-side caching
+	etag := `"` + p.Store.ID(avatarID) + `"`
+	w.Header().Set("Etag", etag)
+	w.Header().Set("Cache-Control", "max-age=604800") // 7 days
+	if match := r.Header.Get("If-None-Match"); match != "" {
+		if strings.Contains(match, etag) {
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+	}
+
+	avReader, size, err := p.Store.Get(avatarID)
+	if err != nil {
+
+		rest.SendErrorJSON(w, r, http.StatusBadRequest, err, "can't load avatar")
+		return
+	}
+
+	defer func() {
+		if e := avReader.Close(); e != nil {
+			log.Printf("[WARN] can't close avatar reader for %s, %s", avatarID, e)
+		}
+	}()
+
+	w.Header().Set("Content-Type", "image/*")
+	w.Header().Set("Content-Length", strconv.Itoa(size))
+	w.WriteHeader(http.StatusOK)
+	if _, err = io.Copy(w, avReader); err != nil {
+		log.Printf("[WARN] can't send response to %s, %s", r.RemoteAddr, err)
+	}
+}
+
+// resize an image of supported format (PNG, JPG, GIF) to the size of "limit" px of the biggest side
+// (width or height) preserving aspect ratio.
+// Returns original reader if resizing is not needed or failed.
+func (p *Proxy) resize(reader io.Reader, limit int) io.Reader {
+	if reader == nil {
+		log.Print("[WARN] avatar resize(): reader is nil")
+		return nil
+	}
+	if limit <= 0 {
+		log.Print("[DEBUG] avatar resize(): limit should be greater than 0")
+		return reader
+	}
+
+	var teeBuf bytes.Buffer
+	tee := io.TeeReader(reader, &teeBuf)
+	src, _, err := image.Decode(tee)
+	if err != nil {
+		log.Printf("[WARN] avatar resize(): can't decode avatar image, %s", err)
+		return &teeBuf
+	}
+
+	bounds := src.Bounds()
+	w, h := bounds.Dx(), bounds.Dy()
+	if w <= limit && h <= limit || w <= 0 || h <= 0 {
+		log.Print("[DEBUG] resizing image is smaller that the limit or has 0 size")
+		return &teeBuf
+	}
+	newW, newH := w*limit/h, limit
+	if w > h {
+		newW, newH = limit, h*limit/w
+	}
+	m := image.NewRGBA(image.Rect(0, 0, newW, newH))
+	// Slower than `draw.ApproxBiLinear.Scale()` but better quality.
+	draw.BiLinear.Scale(m, m.Bounds(), src, src.Bounds(), draw.Src, nil)
+
+	var out bytes.Buffer
+	if err = png.Encode(&out, m); err != nil {
+		log.Printf("[WARN] avatar resize(): can't encode resized avatar to PNG, %s", err)
+		return &teeBuf
+	}
+	return &out
+}
+func retry(retries int, delay time.Duration, fn func() error) (err error) {
+	for i := 0; i < retries; i++ {
+		if err = fn(); err == nil {
+			return nil
+		}
+		time.Sleep(delay)
+	}
+	return errors.Wrap(err, "retry failed")
+}

backend/vendor/github.com/go-pkgz/auth/avatar/bolt.go

@@ -0,0 +1,136 @@
+package avatar
+
+import (
+	"bytes"
+	"crypto/sha1"
+	"encoding/hex"
+	"io"
+	"io/ioutil"
+	"log"
+
+	bolt "github.com/coreos/bbolt"
+	"github.com/pkg/errors"
+)
+
+// BoltDB implements avatar store with bolt
+// using separate db (file) with "avatars" bucket to keep image bin and "metas" bucket
+// to keep sha1 of picture. avatarID (base file name) used as a key for both.
+type BoltDB struct {
+	fileName string // full path to boltdb
+	db       *bolt.DB
+}
+
+const avatarsBktName = "avatars"
+const metasBktName = "metas"
+
+// NewBoltDB makes bolt avatar store
+func NewBoltDB(fileName string, options bolt.Options) (*BoltDB, error) {
+	db, err := bolt.Open(fileName, 0600, &options)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to make boltdb for %s", fileName)
+	}
+	err = db.Update(func(tx *bolt.Tx) error {
+		if _, e := tx.CreateBucketIfNotExists([]byte(avatarsBktName)); e != nil {
+			return errors.Wrapf(e, "failed to create top level bucket %s", avatarsBktName)
+		}
+		_, e := tx.CreateBucketIfNotExists([]byte(metasBktName))
+		return errors.Wrapf(e, "failed to create top metas bucket %s", metasBktName)
+	})
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to initialize boltdb db %q buckets", fileName)
+	}
+	return &BoltDB{db: db, fileName: fileName}, nil
+}
+
+// Put avatar to bolt, key by avatarID. Trying to resize image and lso calculates sha1 of the file for ID func
+func (b *BoltDB) Put(userID string, reader io.Reader) (avatar string, err error) {
+	id := encodeID(userID)
+
+	avatarID := id + imgSfx
+	err = b.db.Update(func(tx *bolt.Tx) error {
+		buf := &bytes.Buffer{}
+		if _, err = io.Copy(buf, reader); err != nil {
+			return errors.Wrapf(err, "can't read avatar %s", avatarID)
+		}
+
+		if err = tx.Bucket([]byte(avatarsBktName)).Put([]byte(avatarID), buf.Bytes()); err != nil {
+			return errors.Wrapf(err, "can't put to bucket with %s", avatarID)
+		}
+		// store sha1 of the image
+		return tx.Bucket([]byte(metasBktName)).Put([]byte(avatarID), []byte(b.sha1(buf.Bytes(), avatarID)))
+	})
+	return avatarID, err
+}
+
+// Get avatar reader for avatar id.image, avatarID used as the direct key
+func (b *BoltDB) Get(avatarID string) (reader io.ReadCloser, size int, err error) {
+	buf := &bytes.Buffer{}
+	err = b.db.View(func(tx *bolt.Tx) error {
+		data := tx.Bucket([]byte(avatarsBktName)).Get([]byte(avatarID))
+		if data == nil {
+			return errors.Errorf("can't load avatar %s", avatarID)
+		}
+		size, err = buf.Write(data)
+		return errors.Wrapf(err, "failed to write for %s", avatarID)
+	})
+	return ioutil.NopCloser(buf), size, err
+}
+
+// ID returns a fingerprint of the avatar content.
+func (b *BoltDB) ID(avatarID string) (id string) {
+	data := []byte{}
+	err := b.db.View(func(tx *bolt.Tx) error {
+		if data = tx.Bucket([]byte(metasBktName)).Get([]byte(avatarID)); data == nil {
+			return errors.Errorf("can't load avatar's id for %s", avatarID)
+		}
+		return nil
+	})
+
+	if err != nil { // failed to get ID, use encoded avatarID
+		log.Printf("[DEBUG] can't get avatar info '%s', %s", avatarID, err)
+		return encodeID(avatarID)
+	}
+
+	return string(data)
+}
+
+// Remove avatar from bolt
+func (b *BoltDB) Remove(avatarID string) (err error) {
+	return b.db.Update(func(tx *bolt.Tx) error {
+		bkt := tx.Bucket([]byte(avatarsBktName))
+		if bkt.Get([]byte(avatarID)) == nil {
+			return errors.Errorf("avatar key not found, %s", avatarID)
+		}
+		if err = tx.Bucket([]byte(avatarsBktName)).Delete([]byte(avatarID)); err != nil {
+			return errors.Wrapf(err, "can't delete avatar object %s", avatarID)
+		}
+		return errors.Wrapf(tx.Bucket([]byte(metasBktName)).Delete([]byte(avatarID)),
+			"can't delete meta object %s", avatarID)
+	})
+}
+
+// List all avatars (ids) from metas bucket
+// note: id includes .image suffix
+func (b *BoltDB) List() (ids []string, err error) {
+	err = b.db.View(func(tx *bolt.Tx) error {
+		return tx.Bucket([]byte(metasBktName)).ForEach(func(k, _ []byte) error {
+			ids = append(ids, string(k))
+			return nil
+		})
+	})
+	return ids, errors.Wrap(err, "failed to list")
+}
+
+// Close bolt store
+func (b *BoltDB) Close() error {
+	return errors.Wrapf(b.db.Close(), "failed to close %s", b.fileName)
+}
+
+func (b *BoltDB) sha1(data []byte, avatarID string) (id string) {
+	h := sha1.New()
+	if _, err := h.Write(data); err != nil {
+		log.Printf("[DEBUG] can't apply sha1 for content of '%s', %s", avatarID, err)
+		return encodeID(avatarID)
+	}
+	return hex.EncodeToString(h.Sum(nil))
+}

backend/vendor/github.com/go-pkgz/auth/avatar/gridfs.go

@@ -0,0 +1,118 @@
+package avatar
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"log"
+	"time"
+
+	"github.com/globalsign/mgo"
+	"github.com/go-pkgz/mongo"
+	"github.com/pkg/errors"
+)
+
+// NewGridFS makes gridfs (mongo) avatar store
+func NewGridFS(conn *mongo.Connection) *GridFS {
+	return &GridFS{Connection: conn}
+}
+
+// GridFS implements Store for GridFS
+type GridFS struct {
+	Connection *mongo.Connection
+}
+
+// Put avatar to gridfs object, try to resize
+func (gf *GridFS) Put(userID string, reader io.Reader) (avatar string, err error) {
+	id := encodeID(userID)
+	err = gf.Connection.WithDB(func(dbase *mgo.Database) error {
+		fh, e := dbase.GridFS("fs").Create(id + imgSfx)
+		if e != nil {
+			return e
+		}
+		defer func() {
+			if err = fh.Close(); err != nil {
+				log.Printf("[WARN] can't close avatar file %v, %s", fh, err)
+			}
+		}()
+
+		_, e = io.Copy(fh, reader)
+		return e
+	})
+	return id + imgSfx, err
+}
+
+// Get avatar reader for avatar id.image
+func (gf *GridFS) Get(avatar string) (reader io.ReadCloser, size int, err error) {
+	buf := &bytes.Buffer{}
+	err = gf.Connection.WithDB(func(dbase *mgo.Database) error {
+		fh, e := dbase.GridFS("fs").Open(avatar)
+		if e != nil {
+			return errors.Wrapf(e, "can't load avatar %s", avatar)
+		}
+		if _, e = io.Copy(buf, fh); e != nil {
+			return errors.Wrapf(e, "can't copy avatar %s", avatar)
+		}
+		size = int(fh.Size())
+		return fh.Close()
+	})
+	return ioutil.NopCloser(buf), size, err
+}
+
+// ID returns a fingerprint of the avatar content. Uses MD5 because gridfs provides it directly
+func (gf *GridFS) ID(avatar string) (id string) {
+	err := gf.Connection.WithDB(func(dbase *mgo.Database) error {
+		fh, e := dbase.GridFS("fs").Open(avatar)
+		if e != nil {
+			return errors.Wrapf(e, "can't open avatar %s", avatar)
+		}
+		id = fh.MD5()
+		return errors.Wrapf(fh.Close(), "can't close avatar")
+	})
+	if err != nil {
+		log.Printf("[DEBUG] can't get file info '%s', %s", avatar, err)
+		return encodeID(avatar)
+	}
+	return id
+}
+
+// Remove avatar from gridfs
+func (gf *GridFS) Remove(avatar string) error {
+	return gf.Connection.WithDB(func(dbase *mgo.Database) error {
+		fh, e := dbase.GridFS("fs").Open(avatar)
+		if e != nil {
+			return errors.Wrapf(e, "can't get avatar %s", avatar)
+		}
+		if e = fh.Close(); e != nil {
+			log.Printf("[WARN] can't close avatar %s, %s", avatar, e)
+		}
+		return dbase.GridFS("fs").Remove(avatar)
+	})
+}
+
+// List all avatars (ids) on gfs
+// note: id includes .image suffix
+func (gf *GridFS) List() (ids []string, err error) {
+
+	type gfsFile struct {
+		UploadDate time.Time `bson:"uploadDate"`
+		Length     int64     `bson:",minsize"`
+		MD5        string
+		Filename   string `bson:",omitempty"`
+	}
+
+	files := []gfsFile{}
+	err = gf.Connection.WithDB(func(dbase *mgo.Database) error {
+		return dbase.GridFS("fs").Find(nil).All(&files)
+	})
+
+	for _, f := range files {
+		ids = append(ids, f.Filename)
+	}
+	return ids, errors.Wrap(err, "can't list avatars")
+}
+
+// Close gridfs does nothing but satisfies interface
+func (gf *GridFS) Close() error {
+	return nil
+}

backend/vendor/github.com/go-pkgz/auth/avatar/localfs.go

@@ -0,0 +1,123 @@
+package avatar
+
+import (
+	"fmt"
+	"hash/crc64"
+	"io"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/pkg/errors"
+)
+
+// LocalFS implements Store for local file system
+type LocalFS struct {
+	storePath string
+	ctcTable  *crc64.Table
+	once      sync.Once
+}
+
+// NewLocalFS makes file-system avatar store
+func NewLocalFS(storePath string) *LocalFS {
+	return &LocalFS{storePath: storePath}
+}
+
+// Put avatar for userID to file and return avatar's file name (base), like 12345678.image
+// userID can be avatarID as well, in this case encoding just strip .image prefix
+func (fs *LocalFS) Put(userID string, reader io.Reader) (avatar string, err error) {
+	if reader == nil {
+		return "", errors.New("empty reader")
+	}
+	id := encodeID(userID)
+	location := fs.location(id) // location adds partition to path
+
+	if e := os.MkdirAll(location, 0755); e != nil {
+		return "", errors.Wrapf(e, "failed to mkdir avatar location %s", location)
+	}
+
+	avFile := path.Join(location, id+imgSfx)
+	fh, err := os.Create(avFile)
+	if err != nil {
+		return "", errors.Wrapf(err, "can't create file %s", avFile)
+	}
+	defer func() {
+		if e := fh.Close(); e != nil {
+			log.Printf("[WARN] can't close avatar file %s, %s", avFile, e)
+		}
+	}()
+
+	if _, err = io.Copy(fh, reader); err != nil {
+		return "", errors.Wrapf(err, "can't save file %s", avFile)
+	}
+	log.Printf("[DEBUG] put avatar for %s to %s completed", userID, fh.Name())
+	return id + imgSfx, nil
+}
+
+// Get avatar reader for avatar id.image
+func (fs *LocalFS) Get(avatar string) (reader io.ReadCloser, size int, err error) {
+	location := fs.location(strings.TrimSuffix(avatar, imgSfx))
+	avFile := path.Join(location, avatar)
+	fh, err := os.Open(avFile)
+	if err != nil {
+		return nil, 0, errors.Wrapf(err, "can't load avatar %s, id", avatar)
+	}
+	if fi, e := fh.Stat(); e == nil {
+		size = int(fi.Size())
+	}
+	return fh, size, nil
+}
+
+// ID returns a fingerprint of the avatar content.
+func (fs *LocalFS) ID(avatar string) (id string) {
+	location := fs.location(strings.TrimSuffix(avatar, imgSfx))
+	avFile := path.Join(location, avatar)
+	fi, err := os.Stat(avFile)
+	if err != nil {
+		log.Printf("[DEBUG] can't get file info '%s', %s", avFile, err)
+		return encodeID(avatar)
+	}
+	return encodeID(avatar + strconv.FormatInt(fi.ModTime().Unix(), 10))
+}
+
+// Remove avatar file
+func (fs *LocalFS) Remove(avatar string) error {
+	location := fs.location(strings.TrimSuffix(avatar, imgSfx))
+	avFile := path.Join(location, avatar)
+	return os.Remove(avFile)
+}
+
+// List all avatars (ids) on local file system
+// note: id includes .image suffix
+func (fs *LocalFS) List() (ids []string, err error) {
+	err = filepath.Walk(fs.storePath,
+		func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+			if !info.IsDir() && strings.HasSuffix(info.Name(), imgSfx) {
+				ids = append(ids, info.Name())
+			}
+			return nil
+		})
+	return ids, errors.Wrap(err, "can't list avatars")
+}
+
+// Close gridfs does nothing but satisfies interface
+func (fs *LocalFS) Close() error {
+	return nil
+}
+
+// get location (directory) for user id by adding partition to final path in order to keep files
+// in different subdirectories and avoid too many files in a single place.
+// the end result is a full path like this - /tmp/avatars.test/92
+func (fs *LocalFS) location(id string) string {
+	fs.once.Do(func() { fs.ctcTable = crc64.MakeTable(crc64.ECMA) })
+	checksum64 := crc64.Checksum([]byte(id), fs.ctcTable)
+	partition := checksum64 % 100
+	return path.Join(fs.storePath, fmt.Sprintf("%02d", partition))
+}

backend/vendor/github.com/go-pkgz/auth/avatar/store.go

@@ -0,0 +1,62 @@
+package avatar
+
+//go:generate sh -c "mockery -inpkg -name Store -print > /tmp/mock.tmp && mv /tmp/mock.tmp store_mock.go"
+
+import (
+	"crypto/sha1"
+	"strings"
+
+	// Initializing packages for supporting GIF and JPEG formats.
+	_ "image/gif"
+	_ "image/jpeg"
+	"io"
+	"log"
+	"regexp"
+
+	"github.com/go-pkgz/auth/token"
+)
+
+// imgSfx for avatars
+const imgSfx = ".image"
+
+var reValidAvatarID = regexp.MustCompile(`^[a-fA-F0-9]{40}\.image$`)
+
+// Store defines interface to store and and load avatars
+type Store interface {
+	Put(userID string, reader io.Reader) (avatarID string, err error) // save avatar data from the reader and return base name
+	Get(avatarID string) (reader io.ReadCloser, size int, err error)  // load avatar via reader
+	ID(avatarID string) (id string)                                   // unique id of stored avatar's data
+	Remove(avatarID string) error                                     // remove avatar data
+	List() (ids []string, err error)                                  // list all avatar ids
+	Close() error                                                     // close store
+}
+
+// Migrate avatars between stores
+func Migrate(dst Store, src Store) (int, error) {
+	ids, err := src.List()
+	if err != nil {
+		return 0, err
+	}
+	for _, id := range ids {
+		srcReader, _, err := src.Get(id)
+		if err != nil {
+			log.Printf("[WARN] can't get reader for avatar %s", id)
+			continue
+		}
+		if _, err = dst.Put(id, srcReader); err != nil {
+			log.Printf("[WARN] can't put avatar %s", id)
+		}
+		if err = srcReader.Close(); err != nil {
+			log.Printf("[WARN] failed to close avatar %s", id)
+		}
+	}
+	return len(ids), nil
+}
+
+// encodeID hashes id to sha1. Skip encoding for already processed
+func encodeID(id string) string {
+	if reValidAvatarID.MatchString(id) {
+		return strings.TrimSuffix(id, imgSfx) // already encoded, strip .image
+	}
+	return token.HashID(sha1.New(), id)
+}

backend/vendor/github.com/go-pkgz/auth/go.mod

@@ -0,0 +1,23 @@
+module github.com/go-pkgz/auth
+
+require (
+	cloud.google.com/go v0.34.0 // indirect
+	github.com/boltdb/bolt v1.3.1 // indirect
+	github.com/coreos/bbolt v1.3.0
+	github.com/dgrijalva/jwt-go v3.2.0+incompatible
+	github.com/globalsign/mgo v0.0.0-20181015135952-eeefdecb41b8
+	github.com/go-errors/errors v1.0.1
+	github.com/go-pkgz/mongo v1.0.0
+	github.com/go-pkgz/rest v1.1.1
+	github.com/kr/pretty v0.1.0 // indirect
+	github.com/nullrocks/identicon v0.0.0-20180626043057-7875f45b0022
+	github.com/pkg/errors v0.8.0
+	github.com/stretchr/testify v1.2.2
+	golang.org/x/image v0.0.0-20181116024801-cd38e8056d9b
+	golang.org/x/net v0.0.0-20181220203305-927f97764cc3 // indirect
+	golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890
+	golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4 // indirect
+	golang.org/x/sys v0.0.0-20181221143128-b4a75ba826a6 // indirect
+	google.golang.org/appengine v1.4.0 // indirect
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+)

backend/vendor/github.com/go-pkgz/auth/go.sum

@@ -0,0 +1,50 @@
+cloud.google.com/go v0.34.0 h1:eOI3/cP2VTU6uZLDYAoic+eyzzB9YyGmJ7eIjl8rOPg=
+cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/boltdb/bolt v1.3.1 h1:JQmyP4ZBrce+ZQu0dY660FMfatumYDLun9hBCUVIkF4=
+github.com/boltdb/bolt v1.3.1/go.mod h1:clJnj/oiGkjum5o1McbSZDSLxVThjynRyGBgiAx27Ps=
+github.com/coreos/bbolt v1.3.0 h1:HIgH5xUWXT914HCI671AxuTTqjj64UOFr7pHn48LUTI=
+github.com/coreos/bbolt v1.3.0/go.mod h1:iRUV2dpdMOn7Bo10OQBFzIJO9kkE559Wcmn+qkEiiKk=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
+github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
+github.com/globalsign/mgo v0.0.0-20181015135952-eeefdecb41b8 h1:DujepqpGd1hyOd7aW59XpK7Qymp8iy83xq74fLr21is=
+github.com/globalsign/mgo v0.0.0-20181015135952-eeefdecb41b8/go.mod h1:xkRDCp4j0OGD1HRkm4kmhM+pmpv3AKq5SU7GMg4oO/Q=
+github.com/go-errors/errors v1.0.1 h1:LUHzmkK3GUKUrL/1gfBUxAHzcev3apQlezX/+O7ma6w=
+github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
+github.com/go-pkgz/mongo v1.0.0 h1:9jijAK7prCRMetiyTu3c1rv/2lMypzuf2DWcVpTlwzw=
+github.com/go-pkgz/mongo v1.0.0/go.mod h1:R9si/F2aJsjz4MUxhzuppIHY8yLV3YCeuCpgcI50cu4=
+github.com/go-pkgz/rest v1.1.1 h1:YuLe+wOJwcE+Y0SkJ+AtvUOPGjTMe4Q4vg98Uqs9CKc=
+github.com/go-pkgz/rest v1.1.1/go.mod h1:DIxxm3vSt6e+IY+UQUOFsfB2YaHLmGoOfPLWN5pxQSA=
+github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/nullrocks/identicon v0.0.0-20180626043057-7875f45b0022 h1:Ys0rDzh8s4UMlGaDa1UTA0sfKgvF0hQZzTYX8ktjiDc=
+github.com/nullrocks/identicon v0.0.0-20180626043057-7875f45b0022/go.mod h1:x4NsS+uc7ecH/Cbm9xKQ6XzmJM57rWTkjywjfB2yQ18=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/image v0.0.0-20181116024801-cd38e8056d9b h1:VHyIDlv3XkfCa5/a81uzaoDkHH4rr81Z62g+xlnO8uM=
+golang.org/x/image v0.0.0-20181116024801-cd38e8056d9b/go.mod h1:ux5Hcp/YLpHSI86hEcLt0YII63i6oz57MZXIpbrjZUs=
+golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20181220203305-927f97764cc3 h1:eH6Eip3UpmR+yM/qI9Ijluzb1bNv/cAU/n+6l8tRSis=
+golang.org/x/net v0.0.0-20181220203305-927f97764cc3/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890 h1:uESlIz09WIHT2I+pasSXcpLYqYK8wHcdCetU3VuMBJE=
+golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4 h1:YUO/7uOKsKeq9UokNS62b8FYywz3ker1l1vDZRCRefw=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20181221143128-b4a75ba826a6 h1:IcgEB62HYgAhX0Nd/QrVgZlxlcyxbGQHElLUhW2X4Fo=
+golang.org/x/sys v0.0.0-20181221143128-b4a75ba826a6/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+google.golang.org/appengine v1.4.0 h1:/wp5JvzpHIxhs/dumFmF7BXTf3Z+dd4uXta4kVyO508=
+google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

backend/vendor/github.com/go-pkgz/auth/middleware/auth.go

@@ -0,0 +1,200 @@
+// Package middleware provides oauth2 support as well as related middlewares.
+package middleware
+
+import (
+	"encoding/base64"
+	"log"
+	"net/http"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/go-pkgz/auth/provider"
+	"github.com/go-pkgz/auth/token"
+)
+
+// Authenticator is top level token object providing middlewares
+type Authenticator struct {
+	JWTService *token.Service
+	Providers  []provider.Service
+	Validator  token.Validator
+	DevPasswd  string
+}
+
+var devUser = token.User{
+	ID:   "dev",
+	Name: "developer one",
+	Attributes: map[string]interface{}{
+		"admin": true,
+	},
+}
+
+var adminUser = token.User{
+	ID:   "admin",
+	Name: "admin",
+	Attributes: map[string]interface{}{
+		"admin": true,
+	},
+}
+
+// Auth middleware adds token from session and populates user info
+func (a *Authenticator) Auth(next http.Handler) http.Handler {
+	return a.auth(true)(next)
+}
+
+// Trace middleware doesn't require valid user but if user info presented populates info
+func (a *Authenticator) Trace(next http.Handler) http.Handler {
+	return a.auth(false)(next)
+}
+
+func (a *Authenticator) auth(reqAuth bool) func(http.Handler) http.Handler {
+
+	onError := func(h http.Handler, w http.ResponseWriter, r *http.Request, err error) {
+		if err == nil {
+			return
+		}
+		if !reqAuth {
+			h.ServeHTTP(w, r)
+			return
+		}
+		log.Printf("[DEBUG] failed token, %s", err)
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+	}
+
+	f := func(h http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+
+			// if secret key matches for given site (from request) return admin user
+			if a.checkSecretKey(r) {
+				r = token.SetUserInfo(r, adminUser)
+				h.ServeHTTP(w, r)
+				return
+			}
+
+			// use dev user basic token if enabled
+			if a.basicDevUser(r) {
+				r = token.SetUserInfo(r, devUser)
+				h.ServeHTTP(w, r)
+				return
+			}
+
+			claims, tkn, err := a.JWTService.Get(r)
+			if err != nil {
+				onError(h, w, r, errors.Wrap(err, "can't get token"))
+				return
+			}
+
+			if claims.Handshake != nil { // handshake in token indicate special use cases, not for login
+				onError(h, w, r, errors.Errorf("invalid kind of token for %s/%s", claims.User.Name, claims.User.ID))
+				return
+			}
+
+			if claims.User == nil {
+				onError(h, w, r, errors.New("failed token, no user info presented in the claim"))
+				return
+			}
+
+			if claims.User != nil { // if uinfo in token populate it to context
+				// validator passed by client and performs check on token or/and claims
+				if a.Validator != nil && !a.Validator.Validate(tkn, claims) {
+					onError(h, w, r, errors.Errorf("user %s/%s blocked", claims.User.Name, claims.User.ID))
+					a.JWTService.Reset(w)
+					return
+				}
+
+				if a.JWTService.IsExpired(claims) {
+					if claims, err = a.refreshExpiredToken(w, claims); err != nil {
+						a.JWTService.Reset(w)
+						onError(h, w, r, errors.Wrap(err, "can't refresh token"))
+						return
+					}
+					log.Printf("[DEBUG] token refreshed for %+v", claims.User)
+				}
+
+				r = token.SetUserInfo(r, *claims.User) // populate user info to request context
+			}
+
+			h.ServeHTTP(w, r)
+		}
+		return http.HandlerFunc(fn)
+	}
+	return f
+}
+
+func (a *Authenticator) checkSecretKey(r *http.Request) bool {
+	if a.JWTService.SecretReader == nil {
+		return false
+	}
+
+	aud := r.URL.Query().Get("aud")
+	secret := r.URL.Query().Get("secret")
+
+	skey, err := a.JWTService.SecretReader.Get(aud)
+	if err != nil {
+		return false
+	}
+
+	if strings.TrimSpace(secret) == "" || secret != skey {
+		return false
+	}
+	return true
+}
+
+// refreshExpiredToken makes new token with passed claims, but only if permission allowed
+func (a *Authenticator) refreshExpiredToken(w http.ResponseWriter, claims token.Claims) (token.Claims, error) {
+	// refresh token
+	if err := a.JWTService.Set(w, claims, false); err != nil {
+		return token.Claims{}, err
+	}
+	return claims, nil
+}
+
+// AdminOnly middleware allows access for admins only
+func (a *Authenticator) AdminOnly(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+
+		user, err := token.GetUserInfo(r)
+		if err != nil {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+
+		if !user.IsAdmin() {
+			http.Error(w, "Access denied", http.StatusForbidden)
+			return
+		}
+		next.ServeHTTP(w, r)
+	}
+	return http.HandlerFunc(fn)
+}
+
+func (a *Authenticator) basicDevUser(r *http.Request) bool {
+
+	if a.DevPasswd == "" {
+		return false
+	}
+
+	s := strings.SplitN(r.Header.Get("Authorization"), " ", 2)
+	if len(s) != 2 {
+		return false
+	}
+
+	b, err := base64.StdEncoding.DecodeString(s[1])
+	if err != nil {
+		log.Printf("[WARN] dev user token failed, failed to decode %s, %s", s[1], err)
+		return false
+	}
+
+	pair := strings.SplitN(string(b), ":", 2)
+	if len(pair) != 2 {
+		log.Printf("[WARN] dev user token failed, failed to split %s", string(b))
+		return false
+	}
+
+	if pair[0] != "dev" || pair[1] != a.DevPasswd {
+		log.Printf("[WARN] dev user token failed, user/passwd mismatch %+v", pair)
+		return false
+	}
+
+	return true
+}

backend/vendor/github.com/go-pkgz/auth/provider/dev_provider.go

@@ -0,0 +1,199 @@
+package provider
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/nullrocks/identicon"
+	"github.com/pkg/errors"
+	"golang.org/x/oauth2"
+
+	"github.com/go-pkgz/auth/token"
+)
+
+const devAuthPort = 8084
+
+// DevAuthServer is a fake oauth server for development
+// it provides stand-alone server running on its own port and pretending to be the real oauth2. It also provides
+// Dev Provider the same way as normal providers do, i.e. like github, google and others.
+// can run in interactive and non-interactive mode. In interactive mode login attempts will show login form to select
+// desired user name, this is the mode used for development. Non-interactive mode for tests only.
+type DevAuthServer struct {
+	Provider  Service
+	Automatic bool
+
+	username string // unsafe, but fine for dev
+
+	iconGen    *identicon.Generator
+	httpServer *http.Server
+	lock       sync.Mutex
+}
+
+// Run oauth2 dev server on port devAuthPort
+func (d *DevAuthServer) Run() {
+	d.username = "dev_user"
+	log.Printf("[INFO] run local oauth2 dev server on %d, redir url=%s", devAuthPort, d.Provider.RedirectURL)
+	d.lock.Lock()
+	var err error
+	d.iconGen, err = identicon.New("github", 5, 3)
+	if err != nil {
+		log.Printf("[WARN] can't create identicon, %s", err)
+	}
+
+	d.httpServer = &http.Server{
+		Addr: fmt.Sprintf(":%d", devAuthPort),
+		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			log.Printf("[DEBUG] dev oauth request %s %s %+v", r.Method, r.URL, r.Header)
+			switch {
+
+			case strings.HasPrefix(r.URL.Path, "/login/oauth/authorize"):
+
+				// first time it will be called without username and will ask for one
+				if !d.Automatic && (r.ParseForm() != nil || r.Form.Get("username") == "") {
+					if _, err = w.Write([]byte(fmt.Sprintf(devUserForm, r.URL.RawQuery))); err != nil {
+						log.Printf("[WARN] can't write, %s", err)
+					}
+					return
+				}
+
+				if !d.Automatic {
+					d.username = r.Form.Get("username")
+				}
+
+				state := r.URL.Query().Get("state")
+				callbackURL := fmt.Sprintf("%s?code=g0ZGZmNjVmOWI&state=%s", d.Provider.RedirectURL, state)
+				log.Printf("[DEBUG] callback url=%s", callbackURL)
+				w.Header().Add("Location", callbackURL)
+				w.WriteHeader(http.StatusFound)
+
+			case strings.HasPrefix(r.URL.Path, "/login/oauth/access_token"):
+				res := `{
+					"access_token":"MTQ0NjJkZmQ5OTM2NDE1ZTZjNGZmZjI3",
+					"token_type":"bearer",
+					"expires_in":3600,
+					"refresh_token":"IwOGYzYTlmM2YxOTQ5MGE3YmNmMDFkNTVk",
+					"scope":"create",
+					"state":"12345678"
+					}`
+				w.Header().Set("Content-Type", "application/json; charset=utf-8")
+				if _, err = w.Write([]byte(res)); err != nil {
+					w.WriteHeader(http.StatusInternalServerError)
+					return
+				}
+
+			case strings.HasPrefix(r.URL.Path, "/user"):
+				ava := fmt.Sprintf("http://127.0.0.1:%d/avatar?user=%s", devAuthPort, d.username)
+				res := fmt.Sprintf(`{
+					"id": "%s",
+					"name":"%s",
+					"picture":"%s"
+					}`, d.username, d.username, ava)
+
+				w.Header().Set("Content-Type", "application/json; charset=utf-8")
+				if _, err = w.Write([]byte(res)); err != nil {
+					w.WriteHeader(http.StatusInternalServerError)
+					return
+				}
+
+			case strings.HasPrefix(r.URL.Path, "/avatar"):
+				user := r.URL.Query().Get("user")
+				b, e := d.genAvatar(user)
+				if e != nil {
+					w.WriteHeader(http.StatusNotFound)
+					return
+				}
+				if _, err = w.Write(b); err != nil {
+					w.WriteHeader(http.StatusInternalServerError)
+					return
+				}
+
+			default:
+				w.WriteHeader(http.StatusBadRequest)
+			}
+		}),
+	}
+	d.lock.Unlock()
+
+	err = d.httpServer.ListenAndServe()
+	log.Printf("[WARN] dev oauth2 server terminated, %s", err)
+}
+
+// Shutdown oauth2 dev server
+func (d *DevAuthServer) Shutdown() {
+	log.Print("[WARN] shutdown oauth2 dev server")
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	d.lock.Lock()
+	if d.httpServer != nil {
+		if err := d.httpServer.Shutdown(ctx); err != nil {
+			log.Printf("[DEBUG] oauth2 dev shutdown error, %s", err)
+		}
+	}
+	log.Print("[DEBUG] shutdown dev oauth2 server completed")
+	d.lock.Unlock()
+}
+
+// NewDev makes dev oauth2 provider for admin user
+func NewDev(p Params) Service {
+	return initService(p, Service{
+		Name: "dev",
+		Endpoint: oauth2.Endpoint{
+			AuthURL:  fmt.Sprintf("http://127.0.0.1:%d/login/oauth/authorize", devAuthPort),
+			TokenURL: fmt.Sprintf("http://127.0.0.1:%d/login/oauth/access_token", devAuthPort),
+		},
+		RedirectURL: p.URL + "/auth/dev/callback",
+		Scopes:      []string{"user:email"},
+		InfoURL:     fmt.Sprintf("http://127.0.0.1:%d/user", devAuthPort),
+		MapUser: func(data userData, _ []byte) token.User {
+			userInfo := token.User{
+				ID:      data.value("id"),
+				Name:    data.value("name"),
+				Picture: data.value("picture"),
+			}
+			return userInfo
+		},
+	})
+}
+
+func (d *DevAuthServer) genAvatar(user string) ([]byte, error) {
+	if d.iconGen == nil {
+		return nil, errors.Errorf("no iconGen, skip avatar generation for %s", user)
+	}
+
+	ii, err := d.iconGen.Draw(user) // Generate an IdentIcon
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to draw avatar for %s", user)
+	}
+
+	buf := &bytes.Buffer{}
+	err = ii.Png(300, buf)
+	return buf.Bytes(), err
+}
+
+var devUserForm = `
+<html>
+    <head>
+	<title>Dev User</title>
+	<style>
+		form {
+			margin: 100 auto;
+			width: 300px;
+			padding: 1em;
+			border: 1px solid #CCC;
+		}
+	</style>
+    </head>
+	<body>
+		<form action="/login/oauth/authorize?%s" method="post">
+			username: <input type="text" name="username" value="dev_user">
+			<input type="submit" value="Login">
+		</form>
+    </body>
+</html>
+`

backend/vendor/github.com/go-pkgz/auth/provider/providers.go

@@ -0,0 +1,127 @@
+package provider
+
+import (
+	"crypto/sha1"
+	"encoding/json"
+	"fmt"
+
+	"golang.org/x/oauth2/facebook"
+	"golang.org/x/oauth2/github"
+	"golang.org/x/oauth2/google"
+	"golang.org/x/oauth2/yandex"
+
+	"github.com/go-pkgz/auth/token"
+)
+
+// NewGoogle makes google oauth2 provider
+func NewGoogle(p Params) Service {
+	return initService(p, Service{
+		Name:        "google",
+		Endpoint:    google.Endpoint,
+		RedirectURL: p.URL + "/token/google/callback",
+		Scopes:      []string{"https://www.googleapis.com/token/userinfo.profile"},
+		InfoURL:     "https://www.googleapis.com/oauth2/v3/userinfo",
+		MapUser: func(data userData, _ []byte) token.User {
+			userInfo := token.User{
+				// encode email with provider name to avoid collision if same id returned by other provider
+				ID:      "google_" + token.HashID(sha1.New(), data.value("sub")),
+				Name:    data.value("name"),
+				Picture: data.value("picture"),
+			}
+			if userInfo.Name == "" {
+				userInfo.Name = "noname_" + userInfo.ID[8:12]
+			}
+			return userInfo
+		},
+	})
+}
+
+// NewGithub makes github oauth2 provider
+func NewGithub(p Params) Service {
+	return initService(p, Service{
+		Name:        "github",
+		Endpoint:    github.Endpoint,
+		RedirectURL: p.URL + "/token/github/callback",
+		Scopes:      []string{},
+		InfoURL:     "https://api.github.com/user",
+		MapUser: func(data userData, _ []byte) token.User {
+			userInfo := token.User{
+				ID:      "github_" + token.HashID(sha1.New(), data.value("login")),
+				Name:    data.value("name"),
+				Picture: data.value("avatar_url"),
+			}
+			// github may have no user name, use login in this case
+			if userInfo.Name == "" {
+				userInfo.Name = data.value("login")
+			}
+			return userInfo
+		},
+	})
+}
+
+// NewFacebook makes facebook oauth2 provider
+func NewFacebook(p Params) Service {
+
+	// response format for fb /me call
+	type uinfo struct {
+		ID      string `json:"id"`
+		Name    string `json:"name"`
+		Picture struct {
+			Data struct {
+				URL string `json:"url"`
+			} `json:"data"`
+		} `json:"picture"`
+	}
+
+	return initService(p, Service{
+		Name:        "facebook",
+		Endpoint:    facebook.Endpoint,
+		RedirectURL: p.URL + "/token/facebook/callback",
+		Scopes:      []string{"public_profile"},
+		InfoURL:     "https://graph.facebook.com/me?fields=id,name,picture",
+		MapUser: func(data userData, bdata []byte) token.User {
+			userInfo := token.User{
+				ID:   "facebook_" + token.HashID(sha1.New(), data.value("id")),
+				Name: data.value("name"),
+			}
+			if userInfo.Name == "" {
+				userInfo.Name = userInfo.ID[0:16]
+			}
+
+			uinfoJSON := uinfo{}
+			if err := json.Unmarshal(bdata, &uinfoJSON); err == nil {
+				userInfo.Picture = uinfoJSON.Picture.Data.URL
+			}
+			return userInfo
+		},
+	})
+}
+
+// NewYandex makes yandex oauth2 provider
+func NewYandex(p Params) Service {
+	return initService(p, Service{
+		Name:        "yandex",
+		Endpoint:    yandex.Endpoint,
+		RedirectURL: p.URL + "/token/yandex/callback",
+		Scopes:      []string{},
+		// See https://tech.yandex.com/passport/doc/dg/reference/response-docpage/
+		InfoURL: "https://login.yandex.ru/info?format=json",
+		MapUser: func(data userData, _ []byte) token.User {
+			userInfo := token.User{
+				ID:   "yandex_" + token.HashID(sha1.New(), data.value("id")),
+				Name: data.value("display_name"), // using Display Name by default
+			}
+			if userInfo.Name == "" {
+				userInfo.Name = data.value("real_name") // using Real Name (== full name) if Display Name is empty
+			}
+			if userInfo.Name == "" {
+				userInfo.Name = data.value("login") // otherwise using login
+			}
+
+			if data.value("default_avatar_id") != "" {
+				userInfo.Picture = fmt.Sprintf("https://avatars.yandex.net/get-yapic/%s/islands-200", data.value("default_avatar_id"))
+			}
+			return userInfo
+		},
+	})
+}

backend/vendor/github.com/go-pkgz/auth/provider/service.go

@@ -0,0 +1,247 @@
+package provider
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	jwt "github.com/dgrijalva/jwt-go"
+	"github.com/go-pkgz/rest"
+	"github.com/pkg/errors"
+	"golang.org/x/oauth2"
+
+	"github.com/go-pkgz/auth/avatar"
+	"github.com/go-pkgz/auth/token"
+)
+
+// Service represents oauth2 provider
+type Service struct {
+	Params
+	Name        string
+	RedirectURL string
+	InfoURL     string
+	Endpoint    oauth2.Endpoint
+	Scopes      []string
+	MapUser     func(userData, []byte) token.User // map info from InfoURL to User
+	conf        oauth2.Config
+}
+
+// Params to make initialized and ready to use provider
+type Params struct {
+	URL         string
+	JwtService  *token.Service
+	AvatarProxy *avatar.Proxy
+	Cid         string
+	Csecret     string
+	Issuer      string
+}
+
+type userData map[string]interface{}
+
+func (u userData) value(key string) string {
+	// json.Unmarshal converts json "null" value to go's "nil", in this case return empty string
+	if val, ok := u[key]; ok && val != nil {
+		return fmt.Sprintf("%v", val)
+	}
+	return ""
+}
+
+// initService makes token service for given provider
+func initService(p Params, service Service) Service {
+	log.Printf("[INFO] init token service %s", service.Name)
+	service.Params = p
+	service.conf = oauth2.Config{
+		ClientID:     service.Cid,
+		ClientSecret: service.Csecret,
+		RedirectURL:  service.RedirectURL,
+		Scopes:       service.Scopes,
+		Endpoint:     service.Endpoint,
+	}
+
+	log.Printf("[DEBUG] created %s token, id=%s, redir=%s, endpoint=%s",
+		service.Name, service.Cid, service.Endpoint, service.RedirectURL)
+	return service
+}
+
+// Handler returns auth routes for given provider
+func (p Service) Handler(w http.ResponseWriter, r *http.Request) {
+
+	if r.Method != "GET" {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+	if strings.HasSuffix(r.URL.Path, "/login") {
+		p.loginHandler(w, r)
+		return
+	}
+	if strings.HasSuffix(r.URL.Path, "/callback") {
+		p.authHandler(w, r)
+		return
+	}
+	if strings.HasSuffix(r.URL.Path, "/logout") {
+		p.LogoutHandler(w, r)
+		return
+	}
+	w.WriteHeader(http.StatusNotFound)
+}
+
+// loginHandler - GET /login?from=redirect-back-url&site=siteID&session=1
+func (p Service) loginHandler(w http.ResponseWriter, r *http.Request) {
+
+	log.Printf("[DEBUG] login with %s", p.Name)
+	// make state (random) and store in session
+	state, err := p.randToken()
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to make oauth2 state")
+		return
+	}
+
+	cid, err := p.randToken()
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to make claim's id")
+		return
+	}
+
+	claims := token.Claims{
+		Handshake: &token.Handshake{
+			State: state,
+			From:  r.URL.Query().Get("from"),
+		},
+		SessionOnly: r.URL.Query().Get("session") != "" && r.URL.Query().Get("session") != "0",
+		StandardClaims: jwt.StandardClaims{
+			Id:        cid,
+			Audience:  r.URL.Query().Get("site"),
+			ExpiresAt: time.Now().Add(30 * time.Minute).Unix(),
+			NotBefore: time.Now().Add(-1 * time.Minute).Unix(),
+		},
+	}
+
+	if err := p.JwtService.Set(w, claims, false); err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to set token")
+		return
+	}
+
+	// return login url
+	loginURL := p.conf.AuthCodeURL(state)
+	log.Printf("[DEBUG] login url %s, claims=%+v", loginURL, claims)
+
+	http.Redirect(w, r, loginURL, http.StatusFound)
+}
+
+// authHandler fills user info and redirects to "from" url. This is callback url redirected locally by browser
+// GET /callback
+func (p Service) authHandler(w http.ResponseWriter, r *http.Request) {
+	oauthClaims, _, err := p.JwtService.Get(r)
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to get token")
+		return
+	}
+
+	retrievedState := oauthClaims.Handshake.State
+	if retrievedState == "" || retrievedState != r.URL.Query().Get("state") {
+		http.Error(w, fmt.Sprintf("unexpected state %v", retrievedState), http.StatusUnauthorized)
+		return
+	}
+
+	log.Printf("[DEBUG] token with state %s", retrievedState)
+	tok, err := p.conf.Exchange(context.Background(), r.URL.Query().Get("code"))
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "exchange failed")
+		return
+	}
+
+	client := p.conf.Client(context.Background(), tok)
+	uinfo, err := client.Get(p.InfoURL)
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusBadRequest, err, fmt.Sprintf("failed to get client info via %s", p.InfoURL))
+		return
+	}
+
+	defer func() {
+		if e := uinfo.Body.Close(); e != nil {
+			log.Printf("[WARN] failed to close response body, %s", e)
+		}
+	}()
+
+	data, err := ioutil.ReadAll(uinfo.Body)
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to read user info")
+		return
+	}
+
+	jData := map[string]interface{}{}
+	if e := json.Unmarshal(data, &jData); e != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to unmarshal user info")
+		return
+	}
+	log.Printf("[DEBUG] got raw user info %+v", jData)
+
+	u := p.MapUser(jData, data)
+	u = p.setAvatar(u)
+
+	cid, err := p.randToken()
+	if err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to make claim's id")
+		return
+	}
+	claims := token.Claims{
+		User: &u,
+		StandardClaims: jwt.StandardClaims{
+			Issuer:   p.Issuer,
+			Id:       cid,
+			Audience: oauthClaims.Audience,
+		},
+		SessionOnly: oauthClaims.SessionOnly,
+	}
+
+	if err = p.JwtService.Set(w, claims, oauthClaims.SessionOnly); err != nil {
+		rest.SendErrorJSON(w, r, http.StatusInternalServerError, err, "failed to save user info")
+		return
+	}
+
+	log.Printf("[DEBUG] user info %+v", u)
+
+	// redirect to back url if presented in login query params
+	if oauthClaims.Handshake != nil && oauthClaims.Handshake.From != "" {
+		http.Redirect(w, r, oauthClaims.Handshake.From, http.StatusTemporaryRedirect)
+		return
+	}
+	rest.RenderJSON(w, r, &u)
+}
+
+// setAvatar saves avatar and puts proxied URL to u.Picture
+func (p Service) setAvatar(u token.User) token.User {
+	if p.AvatarProxy != nil {
+		if avatarURL, e := p.AvatarProxy.Put(u); e == nil {
+			u.Picture = avatarURL
+		} else {
+			log.Printf("[WARN] failed to set avatar for %+v, %+v", u, e)
+		}
+	}
+	return u
+}
+
+// LogoutHandler - GET /logout
+func (p Service) LogoutHandler(w http.ResponseWriter, r *http.Request) {
+	p.JwtService.Reset(w)
+	log.Printf("[DEBUG] logout")
+}
+
+func (p Service) randToken() (string, error) {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		return "", errors.Wrap(err, "can't get random")
+	}
+	s := sha1.New()
+	if _, err := s.Write(b); err != nil {
+		return "", errors.Wrap(err, "can't write randoms to sha1")
+	}
+	return fmt.Sprintf("%x", s.Sum(nil)), nil
+}

backend/vendor/github.com/go-pkgz/auth/token/jwt.go

@@ -0,0 +1,282 @@
+package token
+
+import (
+	"net/http"
+	"time"
+
+	jwt "github.com/dgrijalva/jwt-go"
+	"github.com/pkg/errors"
+)
+
+// Service wraps jwt operations
+// supports both header and cookie tokens
+type Service struct {
+	Opts
+}
+
+// Claims stores user info for token and state & from from login
+type Claims struct {
+	jwt.StandardClaims
+	User        *User      `json:"user,omitempty"` // user info
+	SessionOnly bool       `json:"sess_only,omitempty"`
+	Handshake   *Handshake `json:"handshake,omitempty"` // used for oauth handshake
+}
+
+// Handshake used for oauth handshake
+type Handshake struct {
+	State string `json:"state,omitempty"`
+	From  string `json:"from,omitempty"`
+	ID    string `json:"id,omitempty"`
+}
+
+// default names for cookies and headers
+const (
+	jwtCookieName  = "JWT"
+	jwtHeaderKey   = "X-JWT"
+	xsrfCookieName = "XSRF-TOKEN"
+	xsrfHeaderKey  = "X-XSRF-TOKEN"
+	issuer         = "go-pkgz/auth"
+	tokenDuration  = time.Minute * 15
+	cookieDuration = time.Hour * 24 * 31
+)
+
+// Opts holds constructor params
+type Opts struct {
+	SecretReader   Secret
+	ClaimsUpd      ClaimsUpdater
+	SecureCookies  bool
+	TokenDuration  time.Duration
+	CookieDuration time.Duration
+	DisableXSRF    bool
+
+	// optional (custom) names for cookies and headers
+	JWTCookieName  string
+	JWTHeaderKey   string
+	XSRFCookieName string
+	XSRFHeaderKey  string
+
+	Issuer string // optional value for iss claim, usually application name
+}
+
+// NewService makes JWT service
+func NewService(opts Opts) *Service {
+	res := Service{Opts: opts}
+
+	setDefault := func(fld *string, def string) {
+		if *fld == "" {
+			*fld = def
+		}
+	}
+
+	setDefault(&res.JWTCookieName, jwtCookieName)
+	setDefault(&res.JWTHeaderKey, jwtHeaderKey)
+	setDefault(&res.XSRFCookieName, xsrfCookieName)
+	setDefault(&res.XSRFHeaderKey, xsrfHeaderKey)
+	setDefault(&res.Issuer, issuer)
+
+	if opts.TokenDuration == 0 {
+		res.TokenDuration = tokenDuration
+	}
+
+	if opts.CookieDuration == 0 {
+		res.CookieDuration = cookieDuration
+	}
+
+	return &res
+}
+
+// Token makes token with claims
+func (j *Service) Token(claims Claims) (string, error) {
+
+	// update claims with ClaimsUpdFunc defined by consumer
+	if j.ClaimsUpd != nil {
+		claims = j.ClaimsUpd.Update(claims)
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+
+	secret, err := j.SecretReader.Get(claims.Audience) // get secret via consumer defined SecretReader
+	if err != nil {
+		return "", errors.Wrap(err, "can't get secret")
+	}
+
+	tokenString, err := token.SignedString([]byte(secret))
+	if err != nil {
+		return "", errors.Wrap(err, "can't sign token token")
+	}
+	return tokenString, nil
+}
+
+// Parse token string and verify. Not checking for expiration
+func (j *Service) Parse(tokenString string) (Claims, error) {
+	parser := jwt.Parser{SkipClaimsValidation: true} // allow parsing of expired tokens
+
+	getAud := func() (aud string, err error) { // parse token without signature check to get id (aud)
+		preToken, _, err := parser.ParseUnverified(tokenString, &Claims{})
+		if err != nil {
+			return "", errors.Wrap(err, "can't pre-parse token")
+		}
+		preClaims, ok := preToken.Claims.(*Claims)
+		if !ok {
+			return "", errors.New("invalid token")
+		}
+		return preClaims.Audience, nil
+	}
+
+	aud, err := getAud()
+	if err != nil {
+		return Claims{}, errors.Wrap(err, "failed to get aud from token token")
+	}
+
+	secret, err := j.SecretReader.Get(aud)
+	if err != nil {
+		return Claims{}, errors.Wrap(err, "can't get secret")
+	}
+
+	token, err := parser.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, errors.Errorf("unexpected signing method: %v", token.Header["alg"])
+		}
+		return []byte(secret), nil
+	})
+	if err != nil {
+		return Claims{}, errors.Wrap(err, "can't parse token")
+	}
+
+	claims, ok := token.Claims.(*Claims)
+	if !ok || !token.Valid {
+		return Claims{}, errors.New("invalid token")
+	}
+
+	return *claims, nil
+}
+
+// Set creates token cookie with xsrf cookie and put it to ResponseWriter
+// accepts claims and sets expiration if none defined. permanent flag means long-living cookie,
+// false makes it session only.
+func (j *Service) Set(w http.ResponseWriter, claims Claims, sessionOnly bool) error {
+	if claims.ExpiresAt == 0 {
+		claims.ExpiresAt = time.Now().Add(j.TokenDuration).Unix()
+	}
+
+	claims.Issuer = j.Issuer
+
+	tokenString, err := j.Token(claims)
+	if err != nil {
+		return errors.Wrap(err, "failed to make token token")
+	}
+
+	cookieExpiration := 0 // session cookie
+	if !sessionOnly {
+		cookieExpiration = int(j.CookieDuration.Seconds())
+	}
+
+	jwtCookie := http.Cookie{Name: jwtCookieName, Value: tokenString, HttpOnly: true, Path: "/",
+		MaxAge: cookieExpiration, Secure: j.SecureCookies}
+	http.SetCookie(w, &jwtCookie)
+
+	xsrfCookie := http.Cookie{Name: xsrfCookieName, Value: claims.Id, HttpOnly: false, Path: "/",
+		MaxAge: cookieExpiration, Secure: j.SecureCookies}
+	http.SetCookie(w, &xsrfCookie)
+
+	return nil
+}
+
+// Get token from header or cookie
+// if cookie used, verify xsrf token to match
+func (j *Service) Get(r *http.Request) (Claims, string, error) {
+
+	fromCookie := false
+	tokenString := ""
+
+	// try to get from X-JWT header
+	if tokenHeader := r.Header.Get(jwtHeaderKey); tokenHeader != "" {
+		tokenString = tokenHeader
+	}
+
+	// try to get from JWT cookie
+	if tokenString == "" {
+		fromCookie = true
+		jc, err := r.Cookie(jwtCookieName)
+		if err != nil {
+			return Claims{}, "", errors.Wrap(err, "token cookie was not presented")
+		}
+		tokenString = jc.Value
+	}
+
+	claims, err := j.Parse(tokenString)
+	if err != nil {
+		return Claims{}, "", errors.Wrap(err, "failed to get token")
+	}
+
+	if j.DisableXSRF {
+		return claims, tokenString, nil
+	}
+
+	if fromCookie && claims.User != nil {
+		xsrf := r.Header.Get(xsrfHeaderKey)
+		if claims.Id != xsrf {
+			return Claims{}, "", errors.New("xsrf mismatch")
+		}
+	}
+	return claims, tokenString, nil
+}
+
+// IsExpired returns true if claims expired
+func (j *Service) IsExpired(claims Claims) bool {
+	return !claims.VerifyExpiresAt(time.Now().Unix(), true)
+}
+
+// Reset token's cookies
+func (j *Service) Reset(w http.ResponseWriter) {
+	jwtCookie := http.Cookie{Name: jwtCookieName, Value: "", HttpOnly: false, Path: "/",
+		MaxAge: -1, Expires: time.Unix(0, 0), Secure: j.SecureCookies}
+	http.SetCookie(w, &jwtCookie)
+
+	xsrfCookie := http.Cookie{Name: xsrfCookieName, Value: "", HttpOnly: false, Path: "/",
+		MaxAge: -1, Expires: time.Unix(0, 0), Secure: j.SecureCookies}
+	http.SetCookie(w, &xsrfCookie)
+}
+
+// Secret defines interface returning secret key for given id (aud)
+type Secret interface {
+	Get(id string) (string, error)
+}
+
+// SecretFunc type is an adapter to allow the use of ordinary functions as Secret. If f is a function
+// with the appropriate signature, SecretFunc(f) is a Handler that calls f.
+type SecretFunc func(id string) (string, error)
+
+// Get calls f(id)
+func (f SecretFunc) Get(id string) (string, error) {
+	return f(id)
+}
+
+// ClaimsUpdater defines interface adding extras to claims
+type ClaimsUpdater interface {
+	Update(claims Claims) Claims
+}
+
+// ClaimsUpdFunc type is an adapter to allow the use of ordinary functions as ClaimsUpdater. If f is a function
+// with the appropriate signature, ClaimsUpdFunc(f) is a Handler that calls f.
+type ClaimsUpdFunc func(claims Claims) Claims
+
+// Update calls f(id)
+func (f ClaimsUpdFunc) Update(claims Claims) Claims {
+	return f(claims)
+}
+
+// Validator defines interface to accept o reject claims with consumer defined logic
+// It works with valid token and allows to reject some, based on token match or user's fields
+type Validator interface {
+	Validate(token string, claims Claims) bool
+}
+
+// ValidatorFunc type is an adapter to allow the use of ordinary functions as Validator. If f is a function
+// with the appropriate signature, ValidatorFunc(f) is a Validator that calls f.
+type ValidatorFunc func(token string, claims Claims) bool
+
+// Validate calls f(id)
+func (f ValidatorFunc) Validate(token string, claims Claims) bool {
+	return f(token, claims)
+}

backend/vendor/github.com/go-pkgz/auth/token/user.go

@@ -0,0 +1,126 @@
+package token
+
+import (
+	"context"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"hash/crc64"
+	"io"
+	"log"
+	"net/http"
+	"regexp"
+
+	"github.com/pkg/errors"
+)
+
+var reValidSha = regexp.MustCompile("^[a-fA-F0-9]{40}$")
+var reValidCrc64 = regexp.MustCompile("^[a-fA-F0-9]{16}$")
+
+const adminAttr = "admin" // predefined attribute key for bool isAdmin status
+
+// User is the basic part of oauth data provided by service
+type User struct {
+	Name    string `json:"name"`
+	ID      string `json:"id"`
+	Picture string `json:"picture"`
+	IP      string `json:"ip,omitempty"`
+	Email   string `json:"email,omitempty"`
+
+	Attributes map[string]interface{} `json:"attrs,omitempty"`
+}
+
+// SetBoolAttr sets boolean attribute
+func (u *User) SetBoolAttr(key string, val bool) {
+	if u.Attributes == nil {
+		u.Attributes = map[string]interface{}{}
+	}
+	u.Attributes[key] = val
+}
+
+// SetStrAttr sets string attribute
+func (u *User) SetStrAttr(key string, val string) {
+	if u.Attributes == nil {
+		u.Attributes = map[string]interface{}{}
+	}
+	u.Attributes[key] = val
+}
+
+// BoolAttr gets boolean attribute
+func (u *User) BoolAttr(key string) bool {
+	r, ok := u.Attributes[key].(bool)
+	if !ok {
+		return false
+	}
+	return r
+}
+
+// StrAttr gets string attribute
+func (u *User) StrAttr(key string) string {
+	r, ok := u.Attributes[key].(string)
+	if !ok {
+		return ""
+	}
+	return r
+}
+
+// SetAdmin is a shortcut to set "admin" attribute
+func (u *User) SetAdmin(val bool) {
+	u.SetBoolAttr(adminAttr, val)
+}
+
+// IsAdmin is a shortcut to get admin attribute
+func (u *User) IsAdmin() bool {
+	return u.BoolAttr(adminAttr)
+}
+
+// HashID tries to has val with hash.Hash and fallback to crc if needed
+func HashID(h hash.Hash, val string) string {
+
+	if reValidSha.MatchString(val) {
+		return val // already hashed or empty
+	}
+
+	if _, err := io.WriteString(h, val); err != nil {
+		// fail back to crc64
+		log.Printf("[WARN] can't hash id %s, %s", val, err)
+		if reValidCrc64.MatchString(val) {
+			return val // already crced
+		}
+		return fmt.Sprintf("%x", crc64.Checksum([]byte(val), crc64.MakeTable(crc64.ECMA)))
+	}
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+type contextKey string
+
+// MustGetUserInfo fails if can't extract user data from the request.
+// should be called from authenticated controllers only
+func MustGetUserInfo(r *http.Request) User {
+	user, err := GetUserInfo(r)
+	if err != nil {
+		panic(err)
+	}
+	return user
+}
+
+// GetUserInfo returns user from request context
+func GetUserInfo(r *http.Request) (user User, err error) {
+
+	ctx := r.Context()
+	if ctx == nil {
+		return User{}, errors.New("no info about user")
+	}
+	if u, ok := ctx.Value(contextKey("user")).(User); ok {
+		return u, nil
+	}
+
+	return User{}, errors.New("user can't be parsed")
+}
+
+// SetUserInfo sets user into request context
+func SetUserInfo(r *http.Request, user User) *http.Request {
+	ctx := r.Context()
+	ctx = context.WithValue(ctx, contextKey("user"), user)
+	return r.WithContext(ctx)
+}