Vendor main dependencies.

vendor/github.com/docker/distribution/registry/client/auth/api_version.go

@@ -0,0 +1,58 @@
+package auth
+
+import (
+	"net/http"
+	"strings"
+)
+
+// APIVersion represents a version of an API including its
+// type and version number.
+type APIVersion struct {
+	// Type refers to the name of a specific API specification
+	// such as "registry"
+	Type string
+
+	// Version is the version of the API specification implemented,
+	// This may omit the revision number and only include
+	// the major and minor version, such as "2.0"
+	Version string
+}
+
+// String returns the string formatted API Version
+func (v APIVersion) String() string {
+	return v.Type + "/" + v.Version
+}
+
+// APIVersions gets the API versions out of an HTTP response using the provided
+// version header as the key for the HTTP header.
+func APIVersions(resp *http.Response, versionHeader string) []APIVersion {
+	versions := []APIVersion{}
+	if versionHeader != "" {
+		for _, supportedVersions := range resp.Header[http.CanonicalHeaderKey(versionHeader)] {
+			for _, version := range strings.Fields(supportedVersions) {
+				versions = append(versions, ParseAPIVersion(version))
+			}
+		}
+	}
+	return versions
+}
+
+// ParseAPIVersion parses an API version string into an APIVersion
+// Format (Expected, not enforced):
+// API version string = <API type> '/' <API version>
+// API type = [a-z][a-z0-9]*
+// API version = [0-9]+(\.[0-9]+)?
+// TODO(dmcgowan): Enforce format, add error condition, remove unknown type
+func ParseAPIVersion(versionStr string) APIVersion {
+	idx := strings.IndexRune(versionStr, '/')
+	if idx == -1 {
+		return APIVersion{
+			Type:    "unknown",
+			Version: versionStr,
+		}
+	}
+	return APIVersion{
+		Type:    strings.ToLower(versionStr[:idx]),
+		Version: versionStr[idx+1:],
+	}
+}

vendor/github.com/docker/distribution/registry/client/auth/challenge/addr.go

@@ -0,0 +1,27 @@
+package challenge
+
+import (
+	"net/url"
+	"strings"
+)
+
+// FROM: https://golang.org/src/net/http/http.go
+// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
+// return true if the string includes a port.
+func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
+
+// FROM: http://golang.org/src/net/http/transport.go
+var portMap = map[string]string{
+	"http":  "80",
+	"https": "443",
+}
+
+// canonicalAddr returns url.Host but always with a ":port" suffix
+// FROM: http://golang.org/src/net/http/transport.go
+func canonicalAddr(url *url.URL) string {
+	addr := url.Host
+	if !hasPort(addr) {
+		return addr + ":" + portMap[url.Scheme]
+	}
+	return addr
+}

vendor/github.com/docker/distribution/registry/client/auth/challenge/authchallenge.go

@@ -0,0 +1,237 @@
+package challenge
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+)
+
+// Challenge carries information from a WWW-Authenticate response header.
+// See RFC 2617.
+type Challenge struct {
+	// Scheme is the auth-scheme according to RFC 2617
+	Scheme string
+
+	// Parameters are the auth-params according to RFC 2617
+	Parameters map[string]string
+}
+
+// Manager manages the challenges for endpoints.
+// The challenges are pulled out of HTTP responses. Only
+// responses which expect challenges should be added to
+// the manager, since a non-unauthorized request will be
+// viewed as not requiring challenges.
+type Manager interface {
+	// GetChallenges returns the challenges for the given
+	// endpoint URL.
+	GetChallenges(endpoint url.URL) ([]Challenge, error)
+
+	// AddResponse adds the response to the challenge
+	// manager. The challenges will be parsed out of
+	// the WWW-Authenicate headers and added to the
+	// URL which was produced the response. If the
+	// response was authorized, any challenges for the
+	// endpoint will be cleared.
+	AddResponse(resp *http.Response) error
+}
+
+// NewSimpleManager returns an instance of
+// Manger which only maps endpoints to challenges
+// based on the responses which have been added the
+// manager. The simple manager will make no attempt to
+// perform requests on the endpoints or cache the responses
+// to a backend.
+func NewSimpleManager() Manager {
+	return &simpleManager{
+		Challanges: make(map[string][]Challenge),
+	}
+}
+
+type simpleManager struct {
+	sync.RWMutex
+	Challanges map[string][]Challenge
+}
+
+func normalizeURL(endpoint *url.URL) {
+	endpoint.Host = strings.ToLower(endpoint.Host)
+	endpoint.Host = canonicalAddr(endpoint)
+}
+
+func (m *simpleManager) GetChallenges(endpoint url.URL) ([]Challenge, error) {
+	normalizeURL(&endpoint)
+
+	m.RLock()
+	defer m.RUnlock()
+	challenges := m.Challanges[endpoint.String()]
+	return challenges, nil
+}
+
+func (m *simpleManager) AddResponse(resp *http.Response) error {
+	challenges := ResponseChallenges(resp)
+	if resp.Request == nil {
+		return fmt.Errorf("missing request reference")
+	}
+	urlCopy := url.URL{
+		Path:   resp.Request.URL.Path,
+		Host:   resp.Request.URL.Host,
+		Scheme: resp.Request.URL.Scheme,
+	}
+	normalizeURL(&urlCopy)
+
+	m.Lock()
+	defer m.Unlock()
+	m.Challanges[urlCopy.String()] = challenges
+	return nil
+}
+
+// Octet types from RFC 2616.
+type octetType byte
+
+var octetTypes [256]octetType
+
+const (
+	isToken octetType = 1 << iota
+	isSpace
+)
+
+func init() {
+	// OCTET      = <any 8-bit sequence of data>
+	// CHAR       = <any US-ASCII character (octets 0 - 127)>
+	// CTL        = <any US-ASCII control character (octets 0 - 31) and DEL (127)>
+	// CR         = <US-ASCII CR, carriage return (13)>
+	// LF         = <US-ASCII LF, linefeed (10)>
+	// SP         = <US-ASCII SP, space (32)>
+	// HT         = <US-ASCII HT, horizontal-tab (9)>
+	// <">        = <US-ASCII double-quote mark (34)>
+	// CRLF       = CR LF
+	// LWS        = [CRLF] 1*( SP | HT )
+	// TEXT       = <any OCTET except CTLs, but including LWS>
+	// separators = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\" | <">
+	//              | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP | HT
+	// token      = 1*<any CHAR except CTLs or separators>
+	// qdtext     = <any TEXT except <">>
+
+	for c := 0; c < 256; c++ {
+		var t octetType
+		isCtl := c <= 31 || c == 127
+		isChar := 0 <= c && c <= 127
+		isSeparator := strings.IndexRune(" \t\"(),/:;<=>?@[]\\{}", rune(c)) >= 0
+		if strings.IndexRune(" \t\r\n", rune(c)) >= 0 {
+			t |= isSpace
+		}
+		if isChar && !isCtl && !isSeparator {
+			t |= isToken
+		}
+		octetTypes[c] = t
+	}
+}
+
+// ResponseChallenges returns a list of authorization challenges
+// for the given http Response. Challenges are only checked if
+// the response status code was a 401.
+func ResponseChallenges(resp *http.Response) []Challenge {
+	if resp.StatusCode == http.StatusUnauthorized {
+		// Parse the WWW-Authenticate Header and store the challenges
+		// on this endpoint object.
+		return parseAuthHeader(resp.Header)
+	}
+
+	return nil
+}
+
+func parseAuthHeader(header http.Header) []Challenge {
+	challenges := []Challenge{}
+	for _, h := range header[http.CanonicalHeaderKey("WWW-Authenticate")] {
+		v, p := parseValueAndParams(h)
+		if v != "" {
+			challenges = append(challenges, Challenge{Scheme: v, Parameters: p})
+		}
+	}
+	return challenges
+}
+
+func parseValueAndParams(header string) (value string, params map[string]string) {
+	params = make(map[string]string)
+	value, s := expectToken(header)
+	if value == "" {
+		return
+	}
+	value = strings.ToLower(value)
+	s = "," + skipSpace(s)
+	for strings.HasPrefix(s, ",") {
+		var pkey string
+		pkey, s = expectToken(skipSpace(s[1:]))
+		if pkey == "" {
+			return
+		}
+		if !strings.HasPrefix(s, "=") {
+			return
+		}
+		var pvalue string
+		pvalue, s = expectTokenOrQuoted(s[1:])
+		if pvalue == "" {
+			return
+		}
+		pkey = strings.ToLower(pkey)
+		params[pkey] = pvalue
+		s = skipSpace(s)
+	}
+	return
+}
+
+func skipSpace(s string) (rest string) {
+	i := 0
+	for ; i < len(s); i++ {
+		if octetTypes[s[i]]&isSpace == 0 {
+			break
+		}
+	}
+	return s[i:]
+}
+
+func expectToken(s string) (token, rest string) {
+	i := 0
+	for ; i < len(s); i++ {
+		if octetTypes[s[i]]&isToken == 0 {
+			break
+		}
+	}
+	return s[:i], s[i:]
+}
+
+func expectTokenOrQuoted(s string) (value string, rest string) {
+	if !strings.HasPrefix(s, "\"") {
+		return expectToken(s)
+	}
+	s = s[1:]
+	for i := 0; i < len(s); i++ {
+		switch s[i] {
+		case '"':
+			return s[:i], s[i+1:]
+		case '\\':
+			p := make([]byte, len(s)-1)
+			j := copy(p, s[:i])
+			escape := true
+			for i = i + 1; i < len(s); i++ {
+				b := s[i]
+				switch {
+				case escape:
+					escape = false
+					p[j] = b
+					j++
+				case b == '\\':
+					escape = true
+				case b == '"':
+					return string(p[:j]), s[i+1:]
+				default:
+					p[j] = b
+					j++
+				}
+			}
+			return "", ""
+		}
+	}
+	return "", ""
+}

vendor/github.com/docker/distribution/registry/client/auth/session.go

@@ -0,0 +1,503 @@
+package auth
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution/registry/client"
+	"github.com/docker/distribution/registry/client/auth/challenge"
+	"github.com/docker/distribution/registry/client/transport"
+)
+
+var (
+	// ErrNoBasicAuthCredentials is returned if a request can't be authorized with
+	// basic auth due to lack of credentials.
+	ErrNoBasicAuthCredentials = errors.New("no basic auth credentials")
+
+	// ErrNoToken is returned if a request is successful but the body does not
+	// contain an authorization token.
+	ErrNoToken = errors.New("authorization server did not include a token in the response")
+)
+
+const defaultClientID = "registry-client"
+
+// AuthenticationHandler is an interface for authorizing a request from
+// params from a "WWW-Authenicate" header for a single scheme.
+type AuthenticationHandler interface {
+	// Scheme returns the scheme as expected from the "WWW-Authenicate" header.
+	Scheme() string
+
+	// AuthorizeRequest adds the authorization header to a request (if needed)
+	// using the parameters from "WWW-Authenticate" method. The parameters
+	// values depend on the scheme.
+	AuthorizeRequest(req *http.Request, params map[string]string) error
+}
+
+// CredentialStore is an interface for getting credentials for
+// a given URL
+type CredentialStore interface {
+	// Basic returns basic auth for the given URL
+	Basic(*url.URL) (string, string)
+
+	// RefreshToken returns a refresh token for the
+	// given URL and service
+	RefreshToken(*url.URL, string) string
+
+	// SetRefreshToken sets the refresh token if none
+	// is provided for the given url and service
+	SetRefreshToken(realm *url.URL, service, token string)
+}
+
+// NewAuthorizer creates an authorizer which can handle multiple authentication
+// schemes. The handlers are tried in order, the higher priority authentication
+// methods should be first. The challengeMap holds a list of challenges for
+// a given root API endpoint (for example "https://registry-1.docker.io/v2/").
+func NewAuthorizer(manager challenge.Manager, handlers ...AuthenticationHandler) transport.RequestModifier {
+	return &endpointAuthorizer{
+		challenges: manager,
+		handlers:   handlers,
+	}
+}
+
+type endpointAuthorizer struct {
+	challenges challenge.Manager
+	handlers   []AuthenticationHandler
+	transport  http.RoundTripper
+}
+
+func (ea *endpointAuthorizer) ModifyRequest(req *http.Request) error {
+	pingPath := req.URL.Path
+	if v2Root := strings.Index(req.URL.Path, "/v2/"); v2Root != -1 {
+		pingPath = pingPath[:v2Root+4]
+	} else if v1Root := strings.Index(req.URL.Path, "/v1/"); v1Root != -1 {
+		pingPath = pingPath[:v1Root] + "/v2/"
+	} else {
+		return nil
+	}
+
+	ping := url.URL{
+		Host:   req.URL.Host,
+		Scheme: req.URL.Scheme,
+		Path:   pingPath,
+	}
+
+	challenges, err := ea.challenges.GetChallenges(ping)
+	if err != nil {
+		return err
+	}
+
+	if len(challenges) > 0 {
+		for _, handler := range ea.handlers {
+			for _, c := range challenges {
+				if c.Scheme != handler.Scheme() {
+					continue
+				}
+				if err := handler.AuthorizeRequest(req, c.Parameters); err != nil {
+					return err
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+// This is the minimum duration a token can last (in seconds).
+// A token must not live less than 60 seconds because older versions
+// of the Docker client didn't read their expiration from the token
+// response and assumed 60 seconds.  So to remain compatible with
+// those implementations, a token must live at least this long.
+const minimumTokenLifetimeSeconds = 60
+
+// Private interface for time used by this package to enable tests to provide their own implementation.
+type clock interface {
+	Now() time.Time
+}
+
+type tokenHandler struct {
+	header    http.Header
+	creds     CredentialStore
+	transport http.RoundTripper
+	clock     clock
+
+	offlineAccess bool
+	forceOAuth    bool
+	clientID      string
+	scopes        []Scope
+
+	tokenLock       sync.Mutex
+	tokenCache      string
+	tokenExpiration time.Time
+}
+
+// Scope is a type which is serializable to a string
+// using the allow scope grammar.
+type Scope interface {
+	String() string
+}
+
+// RepositoryScope represents a token scope for access
+// to a repository.
+type RepositoryScope struct {
+	Repository string
+	Class      string
+	Actions    []string
+}
+
+// String returns the string representation of the repository
+// using the scope grammar
+func (rs RepositoryScope) String() string {
+	repoType := "repository"
+	if rs.Class != "" {
+		repoType = fmt.Sprintf("%s(%s)", repoType, rs.Class)
+	}
+	return fmt.Sprintf("%s:%s:%s", repoType, rs.Repository, strings.Join(rs.Actions, ","))
+}
+
+// RegistryScope represents a token scope for access
+// to resources in the registry.
+type RegistryScope struct {
+	Name    string
+	Actions []string
+}
+
+// String returns the string representation of the user
+// using the scope grammar
+func (rs RegistryScope) String() string {
+	return fmt.Sprintf("registry:%s:%s", rs.Name, strings.Join(rs.Actions, ","))
+}
+
+// TokenHandlerOptions is used to configure a new token handler
+type TokenHandlerOptions struct {
+	Transport   http.RoundTripper
+	Credentials CredentialStore
+
+	OfflineAccess bool
+	ForceOAuth    bool
+	ClientID      string
+	Scopes        []Scope
+}
+
+// An implementation of clock for providing real time data.
+type realClock struct{}
+
+// Now implements clock
+func (realClock) Now() time.Time { return time.Now() }
+
+// NewTokenHandler creates a new AuthenicationHandler which supports
+// fetching tokens from a remote token server.
+func NewTokenHandler(transport http.RoundTripper, creds CredentialStore, scope string, actions ...string) AuthenticationHandler {
+	// Create options...
+	return NewTokenHandlerWithOptions(TokenHandlerOptions{
+		Transport:   transport,
+		Credentials: creds,
+		Scopes: []Scope{
+			RepositoryScope{
+				Repository: scope,
+				Actions:    actions,
+			},
+		},
+	})
+}
+
+// NewTokenHandlerWithOptions creates a new token handler using the provided
+// options structure.
+func NewTokenHandlerWithOptions(options TokenHandlerOptions) AuthenticationHandler {
+	handler := &tokenHandler{
+		transport:     options.Transport,
+		creds:         options.Credentials,
+		offlineAccess: options.OfflineAccess,
+		forceOAuth:    options.ForceOAuth,
+		clientID:      options.ClientID,
+		scopes:        options.Scopes,
+		clock:         realClock{},
+	}
+
+	return handler
+}
+
+func (th *tokenHandler) client() *http.Client {
+	return &http.Client{
+		Transport: th.transport,
+		Timeout:   15 * time.Second,
+	}
+}
+
+func (th *tokenHandler) Scheme() string {
+	return "bearer"
+}
+
+func (th *tokenHandler) AuthorizeRequest(req *http.Request, params map[string]string) error {
+	var additionalScopes []string
+	if fromParam := req.URL.Query().Get("from"); fromParam != "" {
+		additionalScopes = append(additionalScopes, RepositoryScope{
+			Repository: fromParam,
+			Actions:    []string{"pull"},
+		}.String())
+	}
+
+	token, err := th.getToken(params, additionalScopes...)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+
+	return nil
+}
+
+func (th *tokenHandler) getToken(params map[string]string, additionalScopes ...string) (string, error) {
+	th.tokenLock.Lock()
+	defer th.tokenLock.Unlock()
+	scopes := make([]string, 0, len(th.scopes)+len(additionalScopes))
+	for _, scope := range th.scopes {
+		scopes = append(scopes, scope.String())
+	}
+	var addedScopes bool
+	for _, scope := range additionalScopes {
+		scopes = append(scopes, scope)
+		addedScopes = true
+	}
+
+	now := th.clock.Now()
+	if now.After(th.tokenExpiration) || addedScopes {
+		token, expiration, err := th.fetchToken(params, scopes)
+		if err != nil {
+			return "", err
+		}
+
+		// do not update cache for added scope tokens
+		if !addedScopes {
+			th.tokenCache = token
+			th.tokenExpiration = expiration
+		}
+
+		return token, nil
+	}
+
+	return th.tokenCache, nil
+}
+
+type postTokenResponse struct {
+	AccessToken  string    `json:"access_token"`
+	RefreshToken string    `json:"refresh_token"`
+	ExpiresIn    int       `json:"expires_in"`
+	IssuedAt     time.Time `json:"issued_at"`
+	Scope        string    `json:"scope"`
+}
+
+func (th *tokenHandler) fetchTokenWithOAuth(realm *url.URL, refreshToken, service string, scopes []string) (token string, expiration time.Time, err error) {
+	form := url.Values{}
+	form.Set("scope", strings.Join(scopes, " "))
+	form.Set("service", service)
+
+	clientID := th.clientID
+	if clientID == "" {
+		// Use default client, this is a required field
+		clientID = defaultClientID
+	}
+	form.Set("client_id", clientID)
+
+	if refreshToken != "" {
+		form.Set("grant_type", "refresh_token")
+		form.Set("refresh_token", refreshToken)
+	} else if th.creds != nil {
+		form.Set("grant_type", "password")
+		username, password := th.creds.Basic(realm)
+		form.Set("username", username)
+		form.Set("password", password)
+
+		// attempt to get a refresh token
+		form.Set("access_type", "offline")
+	} else {
+		// refuse to do oauth without a grant type
+		return "", time.Time{}, fmt.Errorf("no supported grant type")
+	}
+
+	resp, err := th.client().PostForm(realm.String(), form)
+	if err != nil {
+		return "", time.Time{}, err
+	}
+	defer resp.Body.Close()
+
+	if !client.SuccessStatus(resp.StatusCode) {
+		err := client.HandleErrorResponse(resp)
+		return "", time.Time{}, err
+	}
+
+	decoder := json.NewDecoder(resp.Body)
+
+	var tr postTokenResponse
+	if err = decoder.Decode(&tr); err != nil {
+		return "", time.Time{}, fmt.Errorf("unable to decode token response: %s", err)
+	}
+
+	if tr.RefreshToken != "" && tr.RefreshToken != refreshToken {
+		th.creds.SetRefreshToken(realm, service, tr.RefreshToken)
+	}
+
+	if tr.ExpiresIn < minimumTokenLifetimeSeconds {
+		// The default/minimum lifetime.
+		tr.ExpiresIn = minimumTokenLifetimeSeconds
+		logrus.Debugf("Increasing token expiration to: %d seconds", tr.ExpiresIn)
+	}
+
+	if tr.IssuedAt.IsZero() {
+		// issued_at is optional in the token response.
+		tr.IssuedAt = th.clock.Now().UTC()
+	}
+
+	return tr.AccessToken, tr.IssuedAt.Add(time.Duration(tr.ExpiresIn) * time.Second), nil
+}
+
+type getTokenResponse struct {
+	Token        string    `json:"token"`
+	AccessToken  string    `json:"access_token"`
+	ExpiresIn    int       `json:"expires_in"`
+	IssuedAt     time.Time `json:"issued_at"`
+	RefreshToken string    `json:"refresh_token"`
+}
+
+func (th *tokenHandler) fetchTokenWithBasicAuth(realm *url.URL, service string, scopes []string) (token string, expiration time.Time, err error) {
+
+	req, err := http.NewRequest("GET", realm.String(), nil)
+	if err != nil {
+		return "", time.Time{}, err
+	}
+
+	reqParams := req.URL.Query()
+
+	if service != "" {
+		reqParams.Add("service", service)
+	}
+
+	for _, scope := range scopes {
+		reqParams.Add("scope", scope)
+	}
+
+	if th.offlineAccess {
+		reqParams.Add("offline_token", "true")
+		clientID := th.clientID
+		if clientID == "" {
+			clientID = defaultClientID
+		}
+		reqParams.Add("client_id", clientID)
+	}
+
+	if th.creds != nil {
+		username, password := th.creds.Basic(realm)
+		if username != "" && password != "" {
+			reqParams.Add("account", username)
+			req.SetBasicAuth(username, password)
+		}
+	}
+
+	req.URL.RawQuery = reqParams.Encode()
+
+	resp, err := th.client().Do(req)
+	if err != nil {
+		return "", time.Time{}, err
+	}
+	defer resp.Body.Close()
+
+	if !client.SuccessStatus(resp.StatusCode) {
+		err := client.HandleErrorResponse(resp)
+		return "", time.Time{}, err
+	}
+
+	decoder := json.NewDecoder(resp.Body)
+
+	var tr getTokenResponse
+	if err = decoder.Decode(&tr); err != nil {
+		return "", time.Time{}, fmt.Errorf("unable to decode token response: %s", err)
+	}
+
+	if tr.RefreshToken != "" && th.creds != nil {
+		th.creds.SetRefreshToken(realm, service, tr.RefreshToken)
+	}
+
+	// `access_token` is equivalent to `token` and if both are specified
+	// the choice is undefined.  Canonicalize `access_token` by sticking
+	// things in `token`.
+	if tr.AccessToken != "" {
+		tr.Token = tr.AccessToken
+	}
+
+	if tr.Token == "" {
+		return "", time.Time{}, ErrNoToken
+	}
+
+	if tr.ExpiresIn < minimumTokenLifetimeSeconds {
+		// The default/minimum lifetime.
+		tr.ExpiresIn = minimumTokenLifetimeSeconds
+		logrus.Debugf("Increasing token expiration to: %d seconds", tr.ExpiresIn)
+	}
+
+	if tr.IssuedAt.IsZero() {
+		// issued_at is optional in the token response.
+		tr.IssuedAt = th.clock.Now().UTC()
+	}
+
+	return tr.Token, tr.IssuedAt.Add(time.Duration(tr.ExpiresIn) * time.Second), nil
+}
+
+func (th *tokenHandler) fetchToken(params map[string]string, scopes []string) (token string, expiration time.Time, err error) {
+	realm, ok := params["realm"]
+	if !ok {
+		return "", time.Time{}, errors.New("no realm specified for token auth challenge")
+	}
+
+	// TODO(dmcgowan): Handle empty scheme and relative realm
+	realmURL, err := url.Parse(realm)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("invalid token auth challenge realm: %s", err)
+	}
+
+	service := params["service"]
+
+	var refreshToken string
+
+	if th.creds != nil {
+		refreshToken = th.creds.RefreshToken(realmURL, service)
+	}
+
+	if refreshToken != "" || th.forceOAuth {
+		return th.fetchTokenWithOAuth(realmURL, refreshToken, service, scopes)
+	}
+
+	return th.fetchTokenWithBasicAuth(realmURL, service, scopes)
+}
+
+type basicHandler struct {
+	creds CredentialStore
+}
+
+// NewBasicHandler creaters a new authentiation handler which adds
+// basic authentication credentials to a request.
+func NewBasicHandler(creds CredentialStore) AuthenticationHandler {
+	return &basicHandler{
+		creds: creds,
+	}
+}
+
+func (*basicHandler) Scheme() string {
+	return "basic"
+}
+
+func (bh *basicHandler) AuthorizeRequest(req *http.Request, params map[string]string) error {
+	if bh.creds != nil {
+		username, password := bh.creds.Basic(req.URL)
+		if username != "" && password != "" {
+			req.SetBasicAuth(username, password)
+			return nil
+		}
+	}
+	return ErrNoBasicAuthCredentials
+}