distribution/docs/auth/basic/access.go

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// Package basic provides a simple authentication scheme that checks for the
// user credential hash in an htpasswd formatted file in a configuration-determined
// location.
//
// The use of SHA hashes (htpasswd -s) is enforced since MD5 is insecure and simple
// system crypt() may be as well.
//
// This authentication method MUST be used under TLS, as simple token-replay attack is possible.
package basic
import (
"encoding/base64"
"errors"
"fmt"
"net/http"
"strings"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/registry/auth"
"golang.org/x/net/context"
)
type accessController struct {
realm string
htpasswd *HTPasswd
}
type challenge struct {
realm string
err error
}
var _ auth.AccessController = &accessController{}
var (
ErrPasswordRequired = errors.New("authorization credential required")
ErrInvalidCredential = errors.New("invalid authorization credential")
)
func newAccessController(options map[string]interface{}) (auth.AccessController, error) {
realm, present := options["realm"]
if _, ok := realm.(string); !present || !ok {
return nil, fmt.Errorf(`"realm" must be set for basic access controller`)
}
path, present := options["path"]
if _, ok := path.(string); !present || !ok {
return nil, fmt.Errorf(`"path" must be set for basic access controller`)
}
return &accessController{realm: realm.(string), htpasswd: NewHTPasswd(path.(string))}, nil
}
func (ac *accessController) Authorized(ctx context.Context, accessRecords ...auth.Access) (context.Context, error) {
req, err := ctxu.GetRequest(ctx)
if err != nil {
return nil, err
}
authHeader := req.Header.Get("Authorization")
if authHeader == "" {
challenge := challenge{
realm: ac.realm,
}
return nil, &challenge
}
parts := strings.Split(req.Header.Get("Authorization"), " ")
challenge := challenge{
realm: ac.realm,
}
if len(parts) != 2 || strings.ToLower(parts[0]) != "basic" {
challenge.err = ErrPasswordRequired
return nil, &challenge
}
text, err := base64.StdEncoding.DecodeString(parts[1])
if err != nil {
challenge.err = ErrInvalidCredential
return nil, &challenge
}
credential := strings.Split(string(text), ":")
if len(credential) != 2 {
challenge.err = ErrInvalidCredential
return nil, &challenge
}
if res, _ := ac.htpasswd.AuthenticateUser(credential[0], credential[1]); !res {
challenge.err = ErrInvalidCredential
return nil, &challenge
}
return auth.WithUser(ctx, auth.UserInfo{Name: credential[0]}), nil
}
func (ch *challenge) ServeHTTP(w http.ResponseWriter, r *http.Request) {
header := fmt.Sprintf("Realm realm=%q", ch.realm)
w.Header().Set("WWW-Authenticate", header)
w.WriteHeader(http.StatusUnauthorized)
}
func (ch *challenge) Error() string {
return fmt.Sprintf("basic authentication challenge: %#v", ch)
}
func init() {
auth.Register("basic", auth.InitFunc(newAccessController))
}