feat: support per-host scope hints (#604)

The purpose of this PR is to fix the bug, but new APIs are needed to
avoid breaking changes.
1. Introduce `auth.WithScopesForHost`
2. Introduce `auth.AppendScopesForHost`
3. Introduce `auth.GetScopesForHost` and `auth.GetAllScopesForHost`
4. Introduce `auth.AppendRepositoryScope`

Resolves: #581
Signed-off-by: Lixia (Sylvia) Lei <lixlei@microsoft.com>

Author: Wwwsylvia

content.go

@@ -29,7 +29,6 @@ import (
 	"oras.land/oras-go/v2/internal/docker"
 	"oras.land/oras-go/v2/internal/interfaces"
 	"oras.land/oras-go/v2/internal/platform"
-	"oras.land/oras-go/v2/internal/registryutil"
 	"oras.land/oras-go/v2/internal/syncutil"
 	"oras.land/oras-go/v2/registry"
 	"oras.land/oras-go/v2/registry/remote/auth"
@@ -91,7 +90,7 @@ func TagN(ctx context.Context, target Target, srcReference string, dstReferences
 			if err != nil {
 				return ocispec.Descriptor{}, err
 			}
-			ctx = registryutil.WithScopeHint(ctx, ref, auth.ActionPull, auth.ActionPush)
+			ctx = auth.AppendRepositoryScope(ctx, ref, auth.ActionPull, auth.ActionPush)
 		}
 
 		desc, contentBytes, err := FetchBytes(ctx, target, srcReference, FetchBytesOptions{
@@ -149,7 +148,7 @@ func Tag(ctx context.Context, target Target, src, dst string) (ocispec.Descripto
 			if err != nil {
 				return ocispec.Descriptor{}, err
 			}
-			ctx = registryutil.WithScopeHint(ctx, ref, auth.ActionPull, auth.ActionPush)
+			ctx = auth.AppendRepositoryScope(ctx, ref, auth.ActionPull, auth.ActionPush)
 		}
 		desc, rc, err := refFetcher.FetchReference(ctx, src)
 		if err != nil {

internal/registryutil/auth.go

@@ -177,19 +177,19 @@ func (c *Client) Do(originalReq *http.Request) (*http.Response, error) {
 	// attempt cached auth token
 	var attemptedKey string
 	cache := c.cache()
-	registry := originalReq.Host
-	scheme, err := cache.GetScheme(ctx, registry)
+	host := originalReq.Host
+	scheme, err := cache.GetScheme(ctx, host)
 	if err == nil {
 		switch scheme {
 		case SchemeBasic:
-			token, err := cache.GetToken(ctx, registry, SchemeBasic, "")
+			token, err := cache.GetToken(ctx, host, SchemeBasic, "")
 			if err == nil {
 				req.Header.Set("Authorization", "Basic "+token)
 			}
 		case SchemeBearer:
-			scopes := GetScopes(ctx)
+			scopes := GetAllScopesForHost(ctx, host)
 			attemptedKey = strings.Join(scopes, " ")
-			token, err := cache.GetToken(ctx, registry, SchemeBearer, attemptedKey)
+			token, err := cache.GetToken(ctx, host, SchemeBearer, attemptedKey)
 			if err == nil {
 				req.Header.Set("Authorization", "Bearer "+token)
 			}
@@ -211,8 +211,8 @@ func (c *Client) Do(originalReq *http.Request) (*http.Response, error) {
 	case SchemeBasic:
 		resp.Body.Close()
 
-		token, err := cache.Set(ctx, registry, SchemeBasic, "", func(ctx context.Context) (string, error) {
-			return c.fetchBasicAuth(ctx, registry)
+		token, err := cache.Set(ctx, host, SchemeBasic, "", func(ctx context.Context) (string, error) {
+			return c.fetchBasicAuth(ctx, host)
 		})
 		if err != nil {
 			return nil, fmt.Errorf("%s %q: %w", resp.Request.Method, resp.Request.URL, err)
@@ -223,17 +223,17 @@ func (c *Client) Do(originalReq *http.Request) (*http.Response, error) {
 	case SchemeBearer:
 		resp.Body.Close()
 
-		// merge hinted scopes with challenged scopes
-		scopes := GetScopes(ctx)
-		if scope := params["scope"]; scope != "" {
-			scopes = append(scopes, strings.Split(scope, " ")...)
+		scopes := GetAllScopesForHost(ctx, host)
+		if paramScope := params["scope"]; paramScope != "" {
+			// merge hinted scopes with challenged scopes
+			scopes = append(scopes, strings.Split(paramScope, " ")...)
 			scopes = CleanScopes(scopes)
 		}
 		key := strings.Join(scopes, " ")
 
 		// attempt the cache again if there is a scope change
 		if key != attemptedKey {
-			if token, err := cache.GetToken(ctx, registry, SchemeBearer, key); err == nil {
+			if token, err := cache.GetToken(ctx, host, SchemeBearer, key); err == nil {
 				req = originalReq.Clone(ctx)
 				req.Header.Set("Authorization", "Bearer "+token)
 				if err := rewindRequestBody(req); err != nil {
@@ -254,8 +254,8 @@ func (c *Client) Do(originalReq *http.Request) (*http.Response, error) {
 		// attempt with credentials
 		realm := params["realm"]
 		service := params["service"]
-		token, err := cache.Set(ctx, registry, SchemeBearer, key, func(ctx context.Context) (string, error) {
-			return c.fetchBearerToken(ctx, registry, realm, service, scopes)
+		token, err := cache.Set(ctx, host, SchemeBearer, key, func(ctx context.Context) (string, error) {
+			return c.fetchBearerToken(ctx, host, realm, service, scopes)
 		})
 		if err != nil {
 			return nil, fmt.Errorf("%s %q: %w", resp.Request.Method, resp.Request.URL, err)