// downloadMeta downloads top-level metadata from remote storage and verifies
// it using the given file metadata.
func (c *Client) downloadMeta(name string, m data.FileMeta) ([]byte, error) {
r, size, err := c.download(name, c.remote.GetMeta, m.Hashes)
if err != nil {
if IsNotFound(err) {
return nil, ErrMissingRemoteMetadata{name}
}
return nil, err
}
defer r.Close()
// return ErrWrongSize if the reported size is known and incorrect
if size >= 0 && size != m.Length {
return nil, ErrWrongSize{name, size, m.Length}
}
// wrap the data in a LimitReader so we download at most m.Length bytes
stream := io.LimitReader(r, m.Length)
// read the data, simultaneously writing it to buf and generating metadata
var buf bytes.Buffer
meta, err := util.GenerateFileMeta(io.TeeReader(stream, &buf), m.HashAlgorithms()...)
if err != nil {
return nil, err
}
if err := util.FileMetaEqual(meta, m); err != nil {
return nil, ErrDownloadFailed{name, err}
}
return buf.Bytes(), nil
}
// Download downloads the given target file from remote storage into dest.
//
// dest will be deleted and an error returned in the following situations:
//
// * The target does not exist in the local targets.json
// * The target does not exist in remote storage
// * Metadata cannot be generated for the downloaded data
// * Generated metadata does not match local metadata for the given file
func (c *Client) Download(name string, dest Destination) (err error) {
// delete dest if there is an error
defer func() {
if err != nil {
dest.Delete()
}
}()
// populate c.targets from local storage if not set
if c.targets == nil {
if err := c.getLocalMeta(); err != nil {
return err
}
}
// return ErrUnknownTarget if the file is not in the local targets.json
normalizedName := util.NormalizeTarget(name)
localMeta, ok := c.targets[normalizedName]
if !ok {
return ErrUnknownTarget{name}
}
// get the data from remote storage
r, size, err := c.download(normalizedName, c.remote.GetTarget, localMeta.Hashes)
if err != nil {
return err
}
defer r.Close()
// return ErrWrongSize if the reported size is known and incorrect
if size >= 0 && size != localMeta.Length {
return ErrWrongSize{name, size, localMeta.Length}
}
// wrap the data in a LimitReader so we download at most localMeta.Length bytes
stream := io.LimitReader(r, localMeta.Length)
// read the data, simultaneously writing it to dest and generating metadata
actual, err := util.GenerateFileMeta(io.TeeReader(stream, dest), localMeta.HashAlgorithms()...)
if err != nil {
return ErrDownloadFailed{name, err}
}
// check the data has the correct length and hashes
if err := util.FileMetaEqual(actual, localMeta); err != nil {
if err == util.ErrWrongLength {
return ErrWrongSize{name, actual.Length, localMeta.Length}
}
return ErrDownloadFailed{name, err}
}
return nil
}
// hasMeta checks whether local metadata has the given file meta
func (c *Client) hasMeta(name string, m data.FileMeta) bool {
b, ok := c.localMeta[name]
if !ok {
return false
}
meta, err := util.GenerateFileMeta(bytes.NewReader(b), m.HashAlgorithms()...)
if err != nil {
return false
}
err = util.FileMetaEqual(meta, m)
return err == nil
}
func (InteropSuite) TestGoClientPythonGenerated(c *C) {
// start file server
cwd, err := os.Getwd()
c.Assert(err, IsNil)
testDataDir := filepath.Join(cwd, "testdata")
addr, cleanup := startFileServer(c, testDataDir)
defer cleanup()
for _, dir := range []string{"with-consistent-snapshot", "without-consistent-snapshot"} {
remote, err := HTTPRemoteStore(
fmt.Sprintf("http://%s/%s/repository", addr, dir),
&HTTPRemoteOptions{MetadataPath: "metadata", TargetsPath: "targets"},
)
c.Assert(err, IsNil)
// initiate a client with the root keys
f, err := os.Open(filepath.Join("testdata", dir, "keystore", "root_key.pub"))
c.Assert(err, IsNil)
key := &data.Key{}
c.Assert(json.NewDecoder(f).Decode(key), IsNil)
c.Assert(key.Type, Equals, "ed25519")
c.Assert(key.Value.Public, HasLen, ed25519.PublicKeySize)
client := NewClient(MemoryLocalStore(), remote)
c.Assert(client.Init([]*data.Key{key}, 1), IsNil)
// check update returns the correct updated targets
files, err := client.Update()
c.Assert(err, IsNil)
c.Assert(files, HasLen, len(pythonTargets))
for name, data := range pythonTargets {
file, ok := files[name]
if !ok {
c.Fatalf("expected updated targets to contain %s", name)
}
meta, err := util.GenerateFileMeta(bytes.NewReader(data), file.HashAlgorithms()...)
c.Assert(err, IsNil)
c.Assert(util.FileMetaEqual(file, meta), IsNil)
}
// download the files and check they have the correct content
for name, data := range pythonTargets {
var dest testDestination
c.Assert(client.Download(name, &dest), IsNil)
c.Assert(dest.deleted, Equals, false)
c.Assert(dest.String(), Equals, string(data))
}
}
}
func assertFiles(c *C, files data.Files, names []string) {
c.Assert(files, HasLen, len(names))
for _, name := range names {
target, ok := targetFiles[name]
if !ok {
c.Fatalf("unknown target %s", name)
}
file, ok := files[name]
if !ok {
c.Fatalf("expected files to contain %s", name)
}
meta, err := util.GenerateFileMeta(bytes.NewReader(target), file.HashAlgorithms()...)
c.Assert(err, IsNil)
c.Assert(util.FileMetaEqual(file, meta), IsNil)
}
}
// decodeTargets decodes and verifies targets metadata, sets c.targets and
// returns updated targets.
func (c *Client) decodeTargets(b json.RawMessage) (data.Files, error) {
targets := &data.Targets{}
if err := signed.Unmarshal(b, targets, "targets", c.targetsVer, c.db); err != nil {
return nil, ErrDecodeFailed{"targets.json", err}
}
updatedTargets := make(data.Files)
for path, meta := range targets.Targets {
if local, ok := c.targets[path]; ok {
if err := util.FileMetaEqual(local, meta); err == nil {
continue
}
}
updatedTargets[path] = meta
}
c.targetsVer = targets.Version
c.targets = targets.Targets
return updatedTargets, nil
}