Add client implementation of distribution interface

Adds functionality to create a Repository client which connects to a remote endpoint.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

docs/client/authchallenge.go

@@ -0,0 +1,150 @@
+package client
+
+import (
+	"net/http"
+	"strings"
+)
+
+// Octet types from RFC 2616.
+type octetType byte
+
+// AuthorizationChallenge carries information
+// from a WWW-Authenticate response header.
+type AuthorizationChallenge struct {
+	Scheme     string
+	Parameters map[string]string
+}
+
+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
+	}
+}
+
+func parseAuthHeader(header http.Header) []AuthorizationChallenge {
+	var challenges []AuthorizationChallenge
+	for _, h := range header[http.CanonicalHeaderKey("WWW-Authenticate")] {
+		v, p := parseValueAndParams(h)
+		if v != "" {
+			challenges = append(challenges, AuthorizationChallenge{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 + i; 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 "", ""
+}

docs/client/endpoint.go

@@ -0,0 +1,266 @@
+package client
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution/registry/api/v2"
+)
+
+// Authorizer is used to apply Authorization to an HTTP request
+type Authorizer interface {
+	// Authorizer updates an HTTP request with the needed authorization
+	Authorize(req *http.Request) 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)
+}
+
+// RepositoryEndpoint represents a single host endpoint serving up
+// the distribution API.
+type RepositoryEndpoint struct {
+	Endpoint string
+	Mirror   bool
+
+	Header      http.Header
+	Credentials CredentialStore
+
+	ub *v2.URLBuilder
+}
+
+type nullAuthorizer struct{}
+
+func (na nullAuthorizer) Authorize(req *http.Request) error {
+	return nil
+}
+
+type repositoryTransport struct {
+	Transport  http.RoundTripper
+	Header     http.Header
+	Authorizer Authorizer
+}
+
+func (rt *repositoryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	reqCopy := new(http.Request)
+	*reqCopy = *req
+
+	// Copy existing headers then static headers
+	reqCopy.Header = make(http.Header, len(req.Header)+len(rt.Header))
+	for k, s := range req.Header {
+		reqCopy.Header[k] = append([]string(nil), s...)
+	}
+	for k, s := range rt.Header {
+		reqCopy.Header[k] = append(reqCopy.Header[k], s...)
+	}
+
+	if rt.Authorizer != nil {
+		if err := rt.Authorizer.Authorize(reqCopy); err != nil {
+			return nil, err
+		}
+	}
+
+	logrus.Debugf("HTTP: %s %s", req.Method, req.URL)
+
+	if rt.Transport != nil {
+		return rt.Transport.RoundTrip(reqCopy)
+	}
+	return http.DefaultTransport.RoundTrip(reqCopy)
+}
+
+type authTransport struct {
+	Transport http.RoundTripper
+	Header    http.Header
+}
+
+func (rt *authTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	reqCopy := new(http.Request)
+	*reqCopy = *req
+
+	// Copy existing headers then static headers
+	reqCopy.Header = make(http.Header, len(req.Header)+len(rt.Header))
+	for k, s := range req.Header {
+		reqCopy.Header[k] = append([]string(nil), s...)
+	}
+	for k, s := range rt.Header {
+		reqCopy.Header[k] = append(reqCopy.Header[k], s...)
+	}
+
+	logrus.Debugf("HTTP: %s %s", req.Method, req.URL)
+
+	if rt.Transport != nil {
+		return rt.Transport.RoundTrip(reqCopy)
+	}
+	return http.DefaultTransport.RoundTrip(reqCopy)
+}
+
+// URLBuilder returns a new URL builder
+func (e *RepositoryEndpoint) URLBuilder() (*v2.URLBuilder, error) {
+	if e.ub == nil {
+		var err error
+		e.ub, err = v2.NewURLBuilderFromString(e.Endpoint)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return e.ub, nil
+}
+
+// HTTPClient returns a new HTTP client configured for this endpoint
+func (e *RepositoryEndpoint) HTTPClient(name string) (*http.Client, error) {
+	transport := &repositoryTransport{
+		Header: e.Header,
+	}
+	client := &http.Client{
+		Transport: transport,
+	}
+
+	challenges, err := e.ping(client)
+	if err != nil {
+		return nil, err
+	}
+	actions := []string{"pull"}
+	if !e.Mirror {
+		actions = append(actions, "push")
+	}
+
+	transport.Authorizer = &endpointAuthorizer{
+		client:     &http.Client{Transport: &authTransport{Header: e.Header}},
+		challenges: challenges,
+		creds:      e.Credentials,
+		resource:   "repository",
+		scope:      name,
+		actions:    actions,
+	}
+
+	return client, nil
+}
+
+func (e *RepositoryEndpoint) ping(client *http.Client) ([]AuthorizationChallenge, error) {
+	ub, err := e.URLBuilder()
+	if err != nil {
+		return nil, err
+	}
+	u, err := ub.BuildBaseURL()
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequest("GET", u, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header = make(http.Header, len(e.Header))
+	for k, s := range e.Header {
+		req.Header[k] = append([]string(nil), s...)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var supportsV2 bool
+HeaderLoop:
+	for _, supportedVersions := range resp.Header[http.CanonicalHeaderKey("Docker-Distribution-API-Version")] {
+		for _, versionName := range strings.Fields(supportedVersions) {
+			if versionName == "registry/2.0" {
+				supportsV2 = true
+				break HeaderLoop
+			}
+		}
+	}
+
+	if !supportsV2 {
+		return nil, fmt.Errorf("%s does not appear to be a v2 registry endpoint", e.Endpoint)
+	}
+
+	if resp.StatusCode == http.StatusUnauthorized {
+		// Parse the WWW-Authenticate Header and store the challenges
+		// on this endpoint object.
+		return parseAuthHeader(resp.Header), nil
+	} else if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unable to get valid ping response: %d", resp.StatusCode)
+	}
+
+	return nil, nil
+}
+
+type endpointAuthorizer struct {
+	client     *http.Client
+	challenges []AuthorizationChallenge
+	creds      CredentialStore
+
+	resource string
+	scope    string
+	actions  []string
+
+	tokenLock       sync.Mutex
+	tokenCache      string
+	tokenExpiration time.Time
+}
+
+func (ta *endpointAuthorizer) Authorize(req *http.Request) error {
+	token, err := ta.getToken()
+	if err != nil {
+		return err
+	}
+	if token != "" {
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+	} else if ta.creds != nil {
+		username, password := ta.creds.Basic(req.URL)
+		if username != "" && password != "" {
+			req.SetBasicAuth(username, password)
+		}
+	}
+	return nil
+}
+
+func (ta *endpointAuthorizer) getToken() (string, error) {
+	ta.tokenLock.Lock()
+	defer ta.tokenLock.Unlock()
+	now := time.Now()
+	if now.Before(ta.tokenExpiration) {
+		//log.Debugf("Using cached token for %q", ta.auth.Username)
+		return ta.tokenCache, nil
+	}
+
+	for _, challenge := range ta.challenges {
+		switch strings.ToLower(challenge.Scheme) {
+		case "basic":
+			// no token necessary
+		case "bearer":
+			//log.Debugf("Getting bearer token with %s for %s", challenge.Parameters, ta.auth.Username)
+			params := map[string]string{}
+			for k, v := range challenge.Parameters {
+				params[k] = v
+			}
+			params["scope"] = fmt.Sprintf("%s:%s:%s", ta.resource, ta.scope, strings.Join(ta.actions, ","))
+			token, err := getToken(ta.creds, params, ta.client)
+			if err != nil {
+				return "", err
+			}
+			ta.tokenCache = token
+			ta.tokenExpiration = now.Add(time.Minute)
+
+			return token, nil
+		default:
+			//log.Infof("Unsupported auth scheme: %q", challenge.Scheme)
+		}
+	}
+
+	// Do not expire cache since there are no challenges which use a token
+	ta.tokenExpiration = time.Now().Add(time.Hour * 24)
+
+	return "", nil
+}

docs/client/errors.go

@@ -1,9 +1,14 @@
 package client
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
+	"net/http"
 
 	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/registry/api/v2"
 )
 
 // RepositoryNotFoundError is returned when making an operation against a
@@ -77,3 +82,35 @@ type UnexpectedHTTPStatusError struct {
 func (e *UnexpectedHTTPStatusError) Error() string {
 	return fmt.Sprintf("Received unexpected HTTP status: %s", e.Status)
 }
+
+// UnexpectedHTTPResponseError is returned when an expected HTTP status code
+// is returned, but the content was unexpected and failed to be parsed.
+type UnexpectedHTTPResponseError struct {
+	ParseErr error
+	Response []byte
+}
+
+func (e *UnexpectedHTTPResponseError) Error() string {
+	shortenedResponse := string(e.Response)
+	if len(shortenedResponse) > 15 {
+		shortenedResponse = shortenedResponse[:12] + "..."
+	}
+	return fmt.Sprintf("Error parsing HTTP response: %s: %q", e.ParseErr.Error(), shortenedResponse)
+}
+
+func parseHTTPErrorResponse(response *http.Response) error {
+	var errors v2.Errors
+	body, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return err
+	}
+	decoder := json.NewDecoder(bytes.NewReader(body))
+	err = decoder.Decode(&errors)
+	if err != nil {
+		return &UnexpectedHTTPResponseError{
+			ParseErr: err,
+			Response: body,
+		}
+	}
+	return &errors
+}

docs/client/repository.go

@@ -0,0 +1,657 @@
+package client
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"strconv"
+	"time"
+
+	ctxu "github.com/docker/distribution/context"
+
+	"github.com/docker/distribution/manifest"
+
+	"github.com/docker/distribution/digest"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/registry/api/v2"
+	"golang.org/x/net/context"
+)
+
+// NewRepositoryClient creates a new Repository for the given repository name and endpoint
+func NewRepositoryClient(ctx context.Context, name string, endpoint *RepositoryEndpoint) (distribution.Repository, error) {
+	if err := v2.ValidateRespositoryName(name); err != nil {
+		return nil, err
+	}
+
+	ub, err := endpoint.URLBuilder()
+	if err != nil {
+		return nil, err
+	}
+
+	client, err := endpoint.HTTPClient(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &repository{
+		client:  client,
+		ub:      ub,
+		name:    name,
+		context: ctx,
+		mirror:  endpoint.Mirror,
+	}, nil
+}
+
+type repository struct {
+	client  *http.Client
+	ub      *v2.URLBuilder
+	context context.Context
+	name    string
+	mirror  bool
+}
+
+func (r *repository) Name() string {
+	return r.name
+}
+
+func (r *repository) Layers() distribution.LayerService {
+	return &layers{
+		repository: r,
+	}
+}
+
+func (r *repository) Manifests() distribution.ManifestService {
+	return &manifests{
+		repository: r,
+	}
+}
+
+func (r *repository) Signatures() distribution.SignatureService {
+	return &signatures{
+		repository: r,
+	}
+}
+
+type signatures struct {
+	*repository
+}
+
+func (s *signatures) Get(dgst digest.Digest) ([][]byte, error) {
+	panic("not implemented")
+}
+
+func (s *signatures) Put(dgst digest.Digest, signatures ...[]byte) error {
+	panic("not implemented")
+}
+
+type manifests struct {
+	*repository
+}
+
+func (ms *manifests) Tags() ([]string, error) {
+	panic("not implemented")
+}
+
+func (ms *manifests) Exists(dgst digest.Digest) (bool, error) {
+	return ms.ExistsByTag(dgst.String())
+}
+
+func (ms *manifests) ExistsByTag(tag string) (bool, error) {
+	u, err := ms.ub.BuildManifestURL(ms.name, tag)
+	if err != nil {
+		return false, err
+	}
+
+	resp, err := ms.client.Head(u)
+	if err != nil {
+		return false, err
+	}
+
+	switch {
+	case resp.StatusCode == http.StatusOK:
+		return true, nil
+	case resp.StatusCode == http.StatusNotFound:
+		return false, nil
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return false, parseHTTPErrorResponse(resp)
+	default:
+		return false, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (ms *manifests) Get(dgst digest.Digest) (*manifest.SignedManifest, error) {
+	return ms.GetByTag(dgst.String())
+}
+
+func (ms *manifests) GetByTag(tag string) (*manifest.SignedManifest, error) {
+	u, err := ms.ub.BuildManifestURL(ms.name, tag)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := ms.client.Get(u)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	switch {
+	case resp.StatusCode == http.StatusOK:
+		var sm manifest.SignedManifest
+		decoder := json.NewDecoder(resp.Body)
+
+		if err := decoder.Decode(&sm); err != nil {
+			return nil, err
+		}
+
+		return &sm, nil
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return nil, parseHTTPErrorResponse(resp)
+	default:
+		return nil, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (ms *manifests) Put(m *manifest.SignedManifest) error {
+	manifestURL, err := ms.ub.BuildManifestURL(ms.name, m.Tag)
+	if err != nil {
+		return err
+	}
+
+	putRequest, err := http.NewRequest("PUT", manifestURL, bytes.NewReader(m.Raw))
+	if err != nil {
+		return err
+	}
+
+	resp, err := ms.client.Do(putRequest)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	switch {
+	case resp.StatusCode == http.StatusAccepted:
+		// TODO(dmcgowan): Use or check digest header
+		return nil
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return parseHTTPErrorResponse(resp)
+	default:
+		return &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (ms *manifests) Delete(dgst digest.Digest) error {
+	u, err := ms.ub.BuildManifestURL(ms.name, dgst.String())
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequest("DELETE", u, nil)
+	if err != nil {
+		return err
+	}
+
+	resp, err := ms.client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	switch {
+	case resp.StatusCode == http.StatusOK:
+		return nil
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return parseHTTPErrorResponse(resp)
+	default:
+		return &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+type layers struct {
+	*repository
+}
+
+func sanitizeLocation(location, source string) (string, error) {
+	locationURL, err := url.Parse(location)
+	if err != nil {
+		return "", err
+	}
+
+	if locationURL.Scheme == "" {
+		sourceURL, err := url.Parse(source)
+		if err != nil {
+			return "", err
+		}
+		locationURL = &url.URL{
+			Scheme: sourceURL.Scheme,
+			Host:   sourceURL.Host,
+			Path:   location,
+		}
+		location = locationURL.String()
+	}
+	return location, nil
+}
+
+func (ls *layers) Exists(dgst digest.Digest) (bool, error) {
+	_, err := ls.fetchLayer(dgst)
+	if err != nil {
+		switch err := err.(type) {
+		case distribution.ErrUnknownLayer:
+			return false, nil
+		default:
+			return false, err
+		}
+	}
+
+	return true, nil
+}
+
+func (ls *layers) Fetch(dgst digest.Digest) (distribution.Layer, error) {
+	return ls.fetchLayer(dgst)
+}
+
+func (ls *layers) Upload() (distribution.LayerUpload, error) {
+	u, err := ls.ub.BuildBlobUploadURL(ls.name)
+
+	resp, err := ls.client.Post(u, "", nil)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	switch {
+	case resp.StatusCode == http.StatusAccepted:
+		// TODO(dmcgowan): Check for invalid UUID
+		uuid := resp.Header.Get("Docker-Upload-UUID")
+		location, err := sanitizeLocation(resp.Header.Get("Location"), u)
+		if err != nil {
+			return nil, err
+		}
+
+		return &httpLayerUpload{
+			layers:    ls,
+			uuid:      uuid,
+			startedAt: time.Now(),
+			location:  location,
+		}, nil
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return nil, parseHTTPErrorResponse(resp)
+	default:
+		return nil, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (ls *layers) Resume(uuid string) (distribution.LayerUpload, error) {
+	panic("not implemented")
+}
+
+func (ls *layers) fetchLayer(dgst digest.Digest) (distribution.Layer, error) {
+	u, err := ls.ub.BuildBlobURL(ls.name, dgst)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := ls.client.Head(u)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	switch {
+	case resp.StatusCode == http.StatusOK:
+		lengthHeader := resp.Header.Get("Content-Length")
+		length, err := strconv.ParseInt(lengthHeader, 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing content-length: %v", err)
+		}
+
+		var t time.Time
+		lastModified := resp.Header.Get("Last-Modified")
+		if lastModified != "" {
+			t, err = http.ParseTime(lastModified)
+			if err != nil {
+				return nil, fmt.Errorf("error parsing last-modified: %v", err)
+			}
+		}
+
+		return &httpLayer{
+			layers:    ls,
+			size:      length,
+			digest:    dgst,
+			createdAt: t,
+		}, nil
+	case resp.StatusCode == http.StatusNotFound:
+		return nil, distribution.ErrUnknownLayer{
+			FSLayer: manifest.FSLayer{
+				BlobSum: dgst,
+			},
+		}
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return nil, parseHTTPErrorResponse(resp)
+	default:
+		return nil, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+type httpLayer struct {
+	*layers
+
+	size      int64
+	digest    digest.Digest
+	createdAt time.Time
+
+	rc     io.ReadCloser // remote read closer
+	brd    *bufio.Reader // internal buffered io
+	offset int64
+	err    error
+}
+
+func (hl *httpLayer) CreatedAt() time.Time {
+	return hl.createdAt
+}
+
+func (hl *httpLayer) Digest() digest.Digest {
+	return hl.digest
+}
+
+func (hl *httpLayer) Read(p []byte) (n int, err error) {
+	if hl.err != nil {
+		return 0, hl.err
+	}
+
+	rd, err := hl.reader()
+	if err != nil {
+		return 0, err
+	}
+
+	n, err = rd.Read(p)
+	hl.offset += int64(n)
+
+	// Simulate io.EOR error if we reach filesize.
+	if err == nil && hl.offset >= hl.size {
+		err = io.EOF
+	}
+
+	return n, err
+}
+
+func (hl *httpLayer) Seek(offset int64, whence int) (int64, error) {
+	if hl.err != nil {
+		return 0, hl.err
+	}
+
+	var err error
+	newOffset := hl.offset
+
+	switch whence {
+	case os.SEEK_CUR:
+		newOffset += int64(offset)
+	case os.SEEK_END:
+		newOffset = hl.size + int64(offset)
+	case os.SEEK_SET:
+		newOffset = int64(offset)
+	}
+
+	if newOffset < 0 {
+		err = fmt.Errorf("cannot seek to negative position")
+	} else {
+		if hl.offset != newOffset {
+			hl.reset()
+		}
+
+		// No problems, set the offset.
+		hl.offset = newOffset
+	}
+
+	return hl.offset, err
+}
+
+func (hl *httpLayer) Close() error {
+	if hl.err != nil {
+		return hl.err
+	}
+
+	// close and release reader chain
+	if hl.rc != nil {
+		hl.rc.Close()
+	}
+
+	hl.rc = nil
+	hl.brd = nil
+
+	hl.err = fmt.Errorf("httpLayer: closed")
+
+	return nil
+}
+
+func (hl *httpLayer) reset() {
+	if hl.err != nil {
+		return
+	}
+	if hl.rc != nil {
+		hl.rc.Close()
+		hl.rc = nil
+	}
+}
+
+func (hl *httpLayer) reader() (io.Reader, error) {
+	if hl.err != nil {
+		return nil, hl.err
+	}
+
+	if hl.rc != nil {
+		return hl.brd, nil
+	}
+
+	// If the offset is great than or equal to size, return a empty, noop reader.
+	if hl.offset >= hl.size {
+		return ioutil.NopCloser(bytes.NewReader([]byte{})), nil
+	}
+
+	blobURL, err := hl.ub.BuildBlobURL(hl.name, hl.digest)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequest("GET", blobURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	if hl.offset > 0 {
+		// TODO(stevvooe): Get this working correctly.
+
+		// If we are at different offset, issue a range request from there.
+		req.Header.Add("Range", fmt.Sprintf("1-"))
+		ctxu.GetLogger(hl.context).Infof("Range: %s", req.Header.Get("Range"))
+	}
+
+	resp, err := hl.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch {
+	case resp.StatusCode == 200:
+		hl.rc = resp.Body
+	default:
+		defer resp.Body.Close()
+		return nil, fmt.Errorf("unexpected status resolving reader: %v", resp.Status)
+	}
+
+	if hl.brd == nil {
+		hl.brd = bufio.NewReader(hl.rc)
+	} else {
+		hl.brd.Reset(hl.rc)
+	}
+
+	return hl.brd, nil
+}
+
+func (hl *httpLayer) Length() int64 {
+	return hl.size
+}
+
+func (hl *httpLayer) Handler(r *http.Request) (http.Handler, error) {
+	panic("Not implemented")
+}
+
+type httpLayerUpload struct {
+	*layers
+
+	uuid      string
+	startedAt time.Time
+
+	location string // always the last value of the location header.
+	offset   int64
+	closed   bool
+}
+
+var _ distribution.LayerUpload = &httpLayerUpload{}
+
+func (hlu *httpLayerUpload) ReadFrom(r io.Reader) (n int64, err error) {
+	req, err := http.NewRequest("PATCH", hlu.location, r)
+	if err != nil {
+		return 0, err
+	}
+	defer req.Body.Close()
+
+	resp, err := hlu.client.Do(req)
+	if err != nil {
+		return 0, err
+	}
+
+	switch {
+	case resp.StatusCode == http.StatusAccepted:
+		// TODO(dmcgowan): Validate headers
+		hlu.uuid = resp.Header.Get("Docker-Upload-UUID")
+		hlu.location, err = sanitizeLocation(resp.Header.Get("Location"), hlu.location)
+		if err != nil {
+			return 0, err
+		}
+		rng := resp.Header.Get("Range")
+		var start, end int64
+		if n, err := fmt.Sscanf(rng, "%d-%d", &start, &end); err != nil {
+			return 0, err
+		} else if n != 2 || end < start {
+			return 0, fmt.Errorf("bad range format: %s", rng)
+		}
+
+		return (end - start + 1), nil
+	case resp.StatusCode == http.StatusNotFound:
+		return 0, &BlobUploadNotFoundError{Location: hlu.location}
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return 0, parseHTTPErrorResponse(resp)
+	default:
+		return 0, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (hlu *httpLayerUpload) Write(p []byte) (n int, err error) {
+	req, err := http.NewRequest("PATCH", hlu.location, bytes.NewReader(p))
+	if err != nil {
+		return 0, err
+	}
+	req.Header.Set("Content-Range", fmt.Sprintf("%d-%d", hlu.offset, hlu.offset+int64(len(p)-1)))
+	req.Header.Set("Content-Length", fmt.Sprintf("%d", len(p)))
+	req.Header.Set("Content-Type", "application/octet-stream")
+
+	resp, err := hlu.client.Do(req)
+	if err != nil {
+		return 0, err
+	}
+
+	switch {
+	case resp.StatusCode == http.StatusAccepted:
+		// TODO(dmcgowan): Validate headers
+		hlu.uuid = resp.Header.Get("Docker-Upload-UUID")
+		hlu.location, err = sanitizeLocation(resp.Header.Get("Location"), hlu.location)
+		if err != nil {
+			return 0, err
+		}
+		rng := resp.Header.Get("Range")
+		var start, end int
+		if n, err := fmt.Sscanf(rng, "%d-%d", &start, &end); err != nil {
+			return 0, err
+		} else if n != 2 || end < start {
+			return 0, fmt.Errorf("bad range format: %s", rng)
+		}
+
+		return (end - start + 1), nil
+	case resp.StatusCode == http.StatusNotFound:
+		return 0, &BlobUploadNotFoundError{Location: hlu.location}
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return 0, parseHTTPErrorResponse(resp)
+	default:
+		return 0, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (hlu *httpLayerUpload) Seek(offset int64, whence int) (int64, error) {
+	newOffset := hlu.offset
+
+	switch whence {
+	case os.SEEK_CUR:
+		newOffset += int64(offset)
+	case os.SEEK_END:
+		return newOffset, errors.New("Cannot seek from end on incomplete upload")
+	case os.SEEK_SET:
+		newOffset = int64(offset)
+	}
+
+	hlu.offset = newOffset
+
+	return hlu.offset, nil
+}
+
+func (hlu *httpLayerUpload) UUID() string {
+	return hlu.uuid
+}
+
+func (hlu *httpLayerUpload) StartedAt() time.Time {
+	return hlu.startedAt
+}
+
+func (hlu *httpLayerUpload) Finish(digest digest.Digest) (distribution.Layer, error) {
+	// TODO(dmcgowan): Check if already finished, if so just fetch
+	req, err := http.NewRequest("PUT", hlu.location, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	values := req.URL.Query()
+	values.Set("digest", digest.String())
+	req.URL.RawQuery = values.Encode()
+
+	resp, err := hlu.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch {
+	case resp.StatusCode == http.StatusCreated:
+		return hlu.Layers().Fetch(digest)
+	case resp.StatusCode == http.StatusNotFound:
+		return nil, &BlobUploadNotFoundError{Location: hlu.location}
+	case resp.StatusCode >= 400 && resp.StatusCode < 500:
+		return nil, parseHTTPErrorResponse(resp)
+	default:
+		return nil, &UnexpectedHTTPStatusError{Status: resp.Status}
+	}
+}
+
+func (hlu *httpLayerUpload) Cancel() error {
+	panic("not implemented")
+}
+
+func (hlu *httpLayerUpload) Close() error {
+	hlu.closed = true
+	return nil
+}

docs/client/repository_test.go

@@ -0,0 +1,605 @@
+package client
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"code.google.com/p/go-uuid/uuid"
+
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest"
+	"github.com/docker/distribution/testutil"
+	"golang.org/x/net/context"
+)
+
+func testServer(rrm testutil.RequestResponseMap) (*RepositoryEndpoint, func()) {
+	h := testutil.NewHandler(rrm)
+	s := httptest.NewServer(h)
+	e := RepositoryEndpoint{Endpoint: s.URL, Mirror: false}
+	return &e, s.Close
+}
+
+func newRandomBlob(size int) (digest.Digest, []byte) {
+	b := make([]byte, size)
+	if n, err := rand.Read(b); err != nil {
+		panic(err)
+	} else if n != size {
+		panic("unable to read enough bytes")
+	}
+
+	dgst, err := digest.FromBytes(b)
+	if err != nil {
+		panic(err)
+	}
+
+	return dgst, b
+}
+
+func addTestFetch(repo string, dgst digest.Digest, content []byte, m *testutil.RequestResponseMap) {
+	*m = append(*m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "GET",
+			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Body:       content,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(len(content))},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+	*m = append(*m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "HEAD",
+			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(len(content))},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+}
+
+func addPing(m *testutil.RequestResponseMap) {
+	*m = append(*m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "GET",
+			Route:  "/v2/",
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Docker-Distribution-API-Version": {"registry/2.0"},
+			}),
+		},
+	})
+}
+
+func TestLayerFetch(t *testing.T) {
+	d1, b1 := newRandomBlob(1024)
+	var m testutil.RequestResponseMap
+	addTestFetch("test.example.com/repo1", d1, b1, &m)
+	addPing(&m)
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), "test.example.com/repo1", e)
+	if err != nil {
+		t.Fatal(err)
+	}
+	l := r.Layers()
+
+	layer, err := l.Fetch(d1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, err := ioutil.ReadAll(layer)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if bytes.Compare(b, b1) != 0 {
+		t.Fatalf("Wrong bytes values fetched: [%d]byte != [%d]byte", len(b), len(b1))
+	}
+
+	// TODO(dmcgowan): Test error cases
+}
+
+func TestLayerExists(t *testing.T) {
+	d1, b1 := newRandomBlob(1024)
+	var m testutil.RequestResponseMap
+	addTestFetch("test.example.com/repo1", d1, b1, &m)
+	addPing(&m)
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), "test.example.com/repo1", e)
+	if err != nil {
+		t.Fatal(err)
+	}
+	l := r.Layers()
+
+	ok, err := l.Exists(d1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !ok {
+		t.Fatalf("Blob does not exist: %s", d1)
+	}
+
+	// TODO(dmcgowan): Test error cases
+}
+
+func TestLayerUploadChunked(t *testing.T) {
+	dgst, b1 := newRandomBlob(1024)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	chunks := [][]byte{
+		b1[0:256],
+		b1[256:512],
+		b1[512:513],
+		b1[513:1024],
+	}
+	repo := "test.example.com/uploadrepo"
+	uuids := []string{uuid.New()}
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "POST",
+			Route:  "/v2/" + repo + "/blobs/uploads/",
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusAccepted,
+			Headers: http.Header(map[string][]string{
+				"Content-Length":     {"0"},
+				"Location":           {"/v2/" + repo + "/blobs/uploads/" + uuids[0]},
+				"Docker-Upload-UUID": {uuids[0]},
+				"Range":              {"0-0"},
+			}),
+		},
+	})
+	offset := 0
+	for i, chunk := range chunks {
+		uuids = append(uuids, uuid.New())
+		newOffset := offset + len(chunk)
+		m = append(m, testutil.RequestResponseMapping{
+			Request: testutil.Request{
+				Method: "PATCH",
+				Route:  "/v2/" + repo + "/blobs/uploads/" + uuids[i],
+				Body:   chunk,
+			},
+			Response: testutil.Response{
+				StatusCode: http.StatusAccepted,
+				Headers: http.Header(map[string][]string{
+					"Content-Length":     {"0"},
+					"Location":           {"/v2/" + repo + "/blobs/uploads/" + uuids[i+1]},
+					"Docker-Upload-UUID": {uuids[i+1]},
+					"Range":              {fmt.Sprintf("%d-%d", offset, newOffset-1)},
+				}),
+			},
+		})
+		offset = newOffset
+	}
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "PUT",
+			Route:  "/v2/" + repo + "/blobs/uploads/" + uuids[len(uuids)-1],
+			QueryParams: map[string][]string{
+				"digest": {dgst.String()},
+			},
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusCreated,
+			Headers: http.Header(map[string][]string{
+				"Content-Length":        {"0"},
+				"Docker-Content-Digest": {dgst.String()},
+				"Content-Range":         {fmt.Sprintf("0-%d", offset-1)},
+			}),
+		},
+	})
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "HEAD",
+			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(offset)},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+	l := r.Layers()
+
+	upload, err := l.Upload()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if upload.UUID() != uuids[0] {
+		log.Fatalf("Unexpected UUID %s; expected %s", upload.UUID(), uuids[0])
+	}
+
+	for _, chunk := range chunks {
+		n, err := upload.Write(chunk)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if n != len(chunk) {
+			t.Fatalf("Unexpected length returned from write: %d; expected: %d", n, len(chunk))
+		}
+	}
+
+	layer, err := upload.Finish(dgst)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if layer.Length() != int64(len(b1)) {
+		t.Fatalf("Unexpected layer size: %d; expected: %d", layer.Length(), len(b1))
+	}
+}
+
+func TestLayerUploadMonolithic(t *testing.T) {
+	dgst, b1 := newRandomBlob(1024)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	repo := "test.example.com/uploadrepo"
+	uploadID := uuid.New()
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "POST",
+			Route:  "/v2/" + repo + "/blobs/uploads/",
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusAccepted,
+			Headers: http.Header(map[string][]string{
+				"Content-Length":     {"0"},
+				"Location":           {"/v2/" + repo + "/blobs/uploads/" + uploadID},
+				"Docker-Upload-UUID": {uploadID},
+				"Range":              {"0-0"},
+			}),
+		},
+	})
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "PATCH",
+			Route:  "/v2/" + repo + "/blobs/uploads/" + uploadID,
+			Body:   b1,
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusAccepted,
+			Headers: http.Header(map[string][]string{
+				"Location":              {"/v2/" + repo + "/blobs/uploads/" + uploadID},
+				"Docker-Upload-UUID":    {uploadID},
+				"Content-Length":        {"0"},
+				"Docker-Content-Digest": {dgst.String()},
+				"Range":                 {fmt.Sprintf("0-%d", len(b1)-1)},
+			}),
+		},
+	})
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "PUT",
+			Route:  "/v2/" + repo + "/blobs/uploads/" + uploadID,
+			QueryParams: map[string][]string{
+				"digest": {dgst.String()},
+			},
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusCreated,
+			Headers: http.Header(map[string][]string{
+				"Content-Length":        {"0"},
+				"Docker-Content-Digest": {dgst.String()},
+				"Content-Range":         {fmt.Sprintf("0-%d", len(b1)-1)},
+			}),
+		},
+	})
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "HEAD",
+			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(len(b1))},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+	l := r.Layers()
+
+	upload, err := l.Upload()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if upload.UUID() != uploadID {
+		log.Fatalf("Unexpected UUID %s; expected %s", upload.UUID(), uploadID)
+	}
+
+	n, err := upload.ReadFrom(bytes.NewReader(b1))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != int64(len(b1)) {
+		t.Fatalf("Unexpected ReadFrom length: %d; expected: %d", n, len(b1))
+	}
+
+	layer, err := upload.Finish(dgst)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if layer.Length() != int64(len(b1)) {
+		t.Fatalf("Unexpected layer size: %d; expected: %d", layer.Length(), len(b1))
+	}
+}
+
+func TestLayerUploadResume(t *testing.T) {
+	// TODO(dmcgowan): implement
+}
+
+func newRandomSchema1Manifest(name, tag string, blobCount int) (*manifest.SignedManifest, digest.Digest) {
+	blobs := make([]manifest.FSLayer, blobCount)
+	history := make([]manifest.History, blobCount)
+
+	for i := 0; i < blobCount; i++ {
+		dgst, blob := newRandomBlob((i % 5) * 16)
+
+		blobs[i] = manifest.FSLayer{BlobSum: dgst}
+		history[i] = manifest.History{V1Compatibility: fmt.Sprintf("{\"Hex\": \"%x\"}", blob)}
+	}
+
+	m := &manifest.SignedManifest{
+		Manifest: manifest.Manifest{
+			Name:         name,
+			Tag:          tag,
+			Architecture: "x86",
+			FSLayers:     blobs,
+			History:      history,
+			Versioned: manifest.Versioned{
+				SchemaVersion: 1,
+			},
+		},
+	}
+	manifestBytes, err := json.Marshal(m)
+	if err != nil {
+		panic(err)
+	}
+	dgst, err := digest.FromBytes(manifestBytes)
+	if err != nil {
+		panic(err)
+	}
+
+	m.Raw = manifestBytes
+
+	return m, dgst
+}
+
+func addTestManifest(repo, reference string, content []byte, m *testutil.RequestResponseMap) {
+	*m = append(*m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "GET",
+			Route:  "/v2/" + repo + "/manifests/" + reference,
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Body:       content,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(len(content))},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+	*m = append(*m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "HEAD",
+			Route:  "/v2/" + repo + "/manifests/" + reference,
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {fmt.Sprint(len(content))},
+				"Last-Modified":  {time.Now().Add(-1 * time.Second).Format(time.ANSIC)},
+			}),
+		},
+	})
+
+}
+
+func checkEqualManifest(m1, m2 *manifest.SignedManifest) error {
+	if m1.Name != m2.Name {
+		return fmt.Errorf("name does not match %q != %q", m1.Name, m2.Name)
+	}
+	if m1.Tag != m2.Tag {
+		return fmt.Errorf("tag does not match %q != %q", m1.Tag, m2.Tag)
+	}
+	if len(m1.FSLayers) != len(m2.FSLayers) {
+		return fmt.Errorf("fs layer length does not match %d != %d", len(m1.FSLayers), len(m2.FSLayers))
+	}
+	for i := range m1.FSLayers {
+		if m1.FSLayers[i].BlobSum != m2.FSLayers[i].BlobSum {
+			return fmt.Errorf("blobsum does not match %q != %q", m1.FSLayers[i].BlobSum, m2.FSLayers[i].BlobSum)
+		}
+	}
+	if len(m1.History) != len(m2.History) {
+		return fmt.Errorf("history length does not match %d != %d", len(m1.History), len(m2.History))
+	}
+	for i := range m1.History {
+		if m1.History[i].V1Compatibility != m2.History[i].V1Compatibility {
+			return fmt.Errorf("blobsum does not match %q != %q", m1.History[i].V1Compatibility, m2.History[i].V1Compatibility)
+		}
+	}
+	return nil
+}
+
+func TestManifestFetch(t *testing.T) {
+	repo := "test.example.com/repo"
+	m1, dgst := newRandomSchema1Manifest(repo, "latest", 6)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	addTestManifest(repo, dgst.String(), m1.Raw, &m)
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ms := r.Manifests()
+
+	ok, err := ms.Exists(dgst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !ok {
+		t.Fatal("Manifest does not exist")
+	}
+
+	manifest, err := ms.Get(dgst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := checkEqualManifest(manifest, m1); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestManifestFetchByTag(t *testing.T) {
+	repo := "test.example.com/repo/by/tag"
+	m1, _ := newRandomSchema1Manifest(repo, "latest", 6)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	addTestManifest(repo, "latest", m1.Raw, &m)
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ms := r.Manifests()
+	ok, err := ms.ExistsByTag("latest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !ok {
+		t.Fatal("Manifest does not exist")
+	}
+
+	manifest, err := ms.GetByTag("latest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := checkEqualManifest(manifest, m1); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestManifestDelete(t *testing.T) {
+	repo := "test.example.com/repo/delete"
+	_, dgst1 := newRandomSchema1Manifest(repo, "latest", 6)
+	_, dgst2 := newRandomSchema1Manifest(repo, "latest", 6)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "DELETE",
+			Route:  "/v2/" + repo + "/manifests/" + dgst1.String(),
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusOK,
+			Headers: http.Header(map[string][]string{
+				"Content-Length": {"0"},
+			}),
+		},
+	})
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ms := r.Manifests()
+	if err := ms.Delete(dgst1); err != nil {
+		t.Fatal(err)
+	}
+	if err := ms.Delete(dgst2); err == nil {
+		t.Fatal("Expected error deleting unknown manifest")
+	}
+	// TODO(dmcgowan): Check for specific unknown error
+}
+
+func TestManifestPut(t *testing.T) {
+	repo := "test.example.com/repo/delete"
+	m1, dgst := newRandomSchema1Manifest(repo, "other", 6)
+	var m testutil.RequestResponseMap
+	addPing(&m)
+	m = append(m, testutil.RequestResponseMapping{
+		Request: testutil.Request{
+			Method: "PUT",
+			Route:  "/v2/" + repo + "/manifests/other",
+			Body:   m1.Raw,
+		},
+		Response: testutil.Response{
+			StatusCode: http.StatusAccepted,
+			Headers: http.Header(map[string][]string{
+				"Content-Length":        {"0"},
+				"Docker-Content-Digest": {dgst.String()},
+			}),
+		},
+	})
+
+	e, c := testServer(m)
+	defer c()
+
+	r, err := NewRepositoryClient(context.Background(), repo, e)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ms := r.Manifests()
+	if err := ms.Put(m1); err != nil {
+		t.Fatal(err)
+	}
+
+	// TODO(dmcgowan): Check for error cases
+}

docs/client/token.go

@@ -0,0 +1,78 @@
+package client
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type tokenResponse struct {
+	Token string `json:"token"`
+}
+
+func getToken(creds CredentialStore, params map[string]string, client *http.Client) (token string, err error) {
+	realm, ok := params["realm"]
+	if !ok {
+		return "", errors.New("no realm specified for token auth challenge")
+	}
+
+	realmURL, err := url.Parse(realm)
+	if err != nil {
+		return "", fmt.Errorf("invalid token auth challenge realm: %s", err)
+	}
+
+	// TODO(dmcgowan): Handle empty scheme
+
+	req, err := http.NewRequest("GET", realmURL.String(), nil)
+	if err != nil {
+		return "", err
+	}
+
+	reqParams := req.URL.Query()
+	service := params["service"]
+	scope := params["scope"]
+
+	if service != "" {
+		reqParams.Add("service", service)
+	}
+
+	for _, scopeField := range strings.Fields(scope) {
+		reqParams.Add("scope", scopeField)
+	}
+
+	if creds != nil {
+		username, password := creds.Basic(realmURL)
+		if username != "" && password != "" {
+			reqParams.Add("account", username)
+			req.SetBasicAuth(username, password)
+		}
+	}
+
+	req.URL.RawQuery = reqParams.Encode()
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("token auth attempt for registry: %s request failed with status: %d %s", req.URL, resp.StatusCode, http.StatusText(resp.StatusCode))
+	}
+
+	decoder := json.NewDecoder(resp.Body)
+
+	tr := new(tokenResponse)
+	if err = decoder.Decode(tr); err != nil {
+		return "", fmt.Errorf("unable to decode token response: %s", err)
+	}
+
+	if tr.Token == "" {
+		return "", errors.New("authorization server did not include a token in the response")
+	}
+
+	return tr.Token, nil
+}