updating gotuf dep with some better http error handling.

Signed-off-by: David Lawrence <david.lawrence@docker.com> (github: endophage)

Godeps/Godeps.json

@@ -63,7 +63,7 @@
 		},
 		{
 			"ImportPath": "github.com/endophage/gotuf",
-			"Rev": "5be7693587dc2f3c6b35fd1394fcc4e098b4f643"
+			"Rev": "5b7f722ae396b27c59ab5be5e7314a51d1813c29"
 		},
 		{
 			"ImportPath": "github.com/go-sql-driver/mysql",

Godeps/_workspace/src/github.com/endophage/gotuf/client/client.go

@@ -239,6 +239,8 @@ func (c *Client) downloadTimestamp() error {
 			if err == nil {
 				version = ts.Signed.Version
 			}
+		} else {
+			old = nil
 		}
 	}
 	// unlike root, targets and snapshot, always try and download timestamps
@@ -247,7 +249,15 @@ func (c *Client) downloadTimestamp() error {
 	raw, err := c.remote.GetMeta(role, maxSize)
 	var s *data.Signed
 	if err != nil || len(raw) == 0 {
-		if err, ok := err.(*store.ErrMetaNotFound); ok {
+		if err, ok := err.(store.ErrMetaNotFound); ok {
+			return err
+		}
+		if old == nil {
+			if err == nil {
+				// couldn't retrieve data from server and don't have valid
+				// data in cache.
+				return store.ErrMetaNotFound{}
+			}
 			return err
 		}
 		s = old

Godeps/_workspace/src/github.com/endophage/gotuf/store/httpstore.go

@@ -14,6 +14,24 @@ import (
 	"github.com/Sirupsen/logrus"
 )
 
+type ErrServerUnavailable struct{}
+
+func (err ErrServerUnavailable) Error() string {
+	return "Unable to reach trust server at this time."
+}
+
+type ErrShortRead struct{}
+
+func (err ErrShortRead) Error() string {
+	return "Trust server returned incompelete response."
+}
+
+type ErrMaliciousServer struct{}
+
+func (err ErrMaliciousServer) Error() string {
+	return "Trust server returned a bad response."
+}
+
 // HTTPStore manages pulling and pushing metadata from and to a remote
 // service over HTTP. It assumes the URL structure of the remote service
 // maps identically to the structure of the TUF repo:
@@ -67,12 +85,18 @@ func (s HTTPStore) GetMeta(name string, size int64) ([]byte, error) {
 		return nil, err
 	}
 	defer resp.Body.Close()
+	if resp.ContentLength > size {
+		return nil, ErrMaliciousServer{}
+	}
 	logrus.Debugf("%d when retrieving metadata for %s", resp.StatusCode, name)
 	if resp.StatusCode == http.StatusNotFound {
-		return nil, &ErrMetaNotFound{}
+		return nil, ErrMetaNotFound{}
 	}
-	b := io.LimitReader(resp.Body, int64(size))
+	b := io.LimitReader(resp.Body, size)
 	body, err := ioutil.ReadAll(b)
+	if resp.ContentLength > 0 && int64(len(body)) < resp.ContentLength {
+		return nil, ErrShortRead{}
+	}
 
 	if err != nil {
 		return nil, err

client/client.go

@@ -308,7 +308,7 @@ func (r *NotaryRepository) Publish() error {
 	// attempt to initialize the repo from the remote store
 	c, err := r.bootstrapClient()
 	if err != nil {
-		if _, ok := err.(*store.ErrMetaNotFound); ok {
+		if _, ok := err.(store.ErrMetaNotFound); ok {
 			// if the remote store return a 404 (translated into ErrMetaNotFound),
 			// the repo hasn't been initialized yet. Attempt to load it from disk.
 			err := r.bootstrapRepo()
@@ -506,7 +506,7 @@ func (r *NotaryRepository) bootstrapClient() (*tufclient.Client, error) {
 	// if remote store couldn't be setup, or we failed to get a root from it
 	// load the root from cache (offline operation)
 	if err != nil {
-		if err, ok := err.(*store.ErrMetaNotFound); ok {
+		if err, ok := err.(store.ErrMetaNotFound); ok {
 			// if the error was MetaNotFound then we successfully contacted
 			// the store and it doesn't know about the repo.
 			return nil, err
@@ -514,7 +514,7 @@ func (r *NotaryRepository) bootstrapClient() (*tufclient.Client, error) {
 		rootJSON, err = r.fileStore.GetMeta("root", maxSize)
 		if err != nil {
 			// if cache didn't return a root, we cannot proceed
-			return nil, &store.ErrMetaNotFound{}
+			return nil, store.ErrMetaNotFound{}
 		}
 	}
 	root := &data.Signed{}