/
manager.go
90 lines (80 loc) · 2.01 KB
/
manager.go
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package auth
import (
"bytes"
"errors"
"log"
"time"
"golang.org/x/net/context"
"golang.org/x/oauth2/google"
cache "github.com/patrickmn/go-cache"
storage "google.golang.org/api/storage/v1"
)
// Manager provides cached authentication from GCS via user name and token
type Manager struct {
authCache *cache.Cache
gcs *storage.Service
gcsBucket string
}
// NewManager connects to GCS
func NewManager(ctx context.Context, gcsBucket string) (*Manager, error) {
if gcsBucket == "" {
log.Println("Authentication is disabled, no GCS bucket with authentication data provided")
return &Manager{}, nil
}
am := Manager{
// 5 minute TTL, purge every 30 seconds.
authCache: cache.New(5*time.Minute, 30*time.Second),
gcsBucket: gcsBucket,
}
client, err := google.DefaultClient(ctx, storage.DevstorageReadOnlyScope)
if err != nil {
return nil, err
}
am.gcs, err = storage.New(client)
return &am, err
}
func (am *Manager) fetchAuthToken(user string) (string, error) {
r, err := am.gcs.Objects.Get(am.gcsBucket, user).Download()
if err != nil {
return "", err
}
var b bytes.Buffer
_, err = b.ReadFrom(r.Body)
// TODO(dotdoom): encode files in JSON
return string(b.Bytes()), err
}
func (am *Manager) getAuthToken(user string) (string, error) {
token, found := am.authCache.Get(user)
if found {
return token.(string), nil
}
tokenString, err := am.fetchAuthToken(user)
if err == nil {
am.authCache.Set(user, tokenString, cache.DefaultExpiration)
}
return tokenString, err
}
// CheckAccess returns nil if access is granted
func (am *Manager) CheckAccess(user, token string) error {
// TODO(dotdoom): add 3rd parameter, level
// TODO(dotdoom): log auth errors
var (
actualToken string
err error
)
if am.gcs == nil {
actualToken = ""
} else {
actualToken, err = am.getAuthToken(user)
if err != nil {
return err
}
if actualToken == "" {
return errors.New("Cannot verify the token")
}
}
if actualToken != token {
return errors.New("Incorrect token supplied")
}
return nil
}