Example #1
0
// downloadTimestamp is responsible for downloading the timestamp.json
// Timestamps are special in that we ALWAYS attempt to download and only
// use cache if the download fails (and the cache is still valid).
func (c *Client) downloadTimestamp() error {
	logrus.Debug("downloadTimestamp")
	role := data.RoleName("timestamp")

	// We may not have a cached timestamp if this is the first time
	// we're interacting with the repo. This will result in the
	// version being 0
	var download bool
	old := &data.Signed{}
	version := 0
	cachedTS, err := c.cache.GetMeta(role, maxSize)
	if err == nil {
		err := json.Unmarshal(cachedTS, old)
		if err == nil {
			ts, err := data.TimestampFromSigned(old)
			if err == nil {
				version = ts.Signed.Version
			}
		} else {
			old = nil
		}
	}
	// unlike root, targets and snapshot, always try and download timestamps
	// from remote, only using the cache one if we couldn't reach remote.
	raw, s, err := c.downloadSigned(role, maxSize, nil)
	if err != nil || len(raw) == 0 {
		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
		}
		logrus.Debug("using cached timestamp")
		s = old
	} else {
		download = true
	}
	err = signed.Verify(s, role, version, c.keysDB)
	if err != nil {
		return err
	}
	logrus.Debug("successfully verified timestamp")
	if download {
		c.cache.SetMeta(role, raw)
	}
	ts, err := data.TimestampFromSigned(s)
	if err != nil {
		return err
	}
	c.local.SetTimestamp(ts)
	return nil
}
Example #2
0
// SetTimestamp parses the Signed object into a SignedTimestamp object
// and sets the TufRepo.Timestamp field.
func (tr *TufRepo) SetTimestamp(s *data.Signed) error {
	ts, err := data.TimestampFromSigned(s)
	if err != nil {
		return err
	}
	tr.Timestamp = ts
	return nil
}
Example #3
0
// downloadSnapshot is responsible for downloading the snapshot.json
func (c *Client) downloadSnapshot() error {
	logrus.Debug("downloadSnapshot")
	role := data.RoleName("snapshot")
	if c.local.Timestamp == nil {
		return ErrMissingMeta{role: "snapshot"}
	}
	size := c.local.Timestamp.Signed.Meta[role].Length
	expectedSha256, ok := c.local.Timestamp.Signed.Meta[role].Hashes["sha256"]
	if !ok {
		return ErrMissingMeta{role: "snapshot"}
	}

	var download bool
	old := &data.Signed{}
	version := 0
	raw, err := c.cache.GetMeta(role, size)
	if raw == nil || err != nil {
		logrus.Debug("no snapshot in cache, must download")
		download = true
	} else {
		// file may have been tampered with on disk. Always check the hash!
		genHash := sha256.Sum256(raw)
		if !bytes.Equal(genHash[:], expectedSha256) {
			logrus.Debug("hash of snapshot in cache did not match expected hash, must download")
			download = true
		}
		err := json.Unmarshal(raw, old)
		if err == nil {
			snap, err := data.TimestampFromSigned(old)
			if err == nil {
				version = snap.Signed.Version
			} else {
				logrus.Debug("Could not parse Signed part of snapshot, must download")
				download = true
			}
		} else {
			logrus.Debug("Could not parse snapshot, must download")
			download = true
		}
	}
	var s *data.Signed
	if download {
		raw, s, err = c.downloadSigned(role, size, expectedSha256)
		if err != nil {
			return err
		}
	} else {
		logrus.Debug("using cached snapshot")
		s = old
	}

	err = signed.Verify(s, role, version, c.keysDB)
	if err != nil {
		return err
	}
	logrus.Debug("successfully verified snapshot")
	snap, err := data.SnapshotFromSigned(s)
	if err != nil {
		return err
	}
	c.local.SetSnapshot(snap)
	if download {
		err = c.cache.SetMeta(role, raw)
		if err != nil {
			logrus.Errorf("Failed to write snapshot to local cache: %s", err.Error())
		}
	}
	return nil
}
Example #4
0
// downloadSnapshot is responsible for downloading the snapshot.json
func (c *Client) downloadSnapshot() error {
	logrus.Debug("downloadSnapshot")
	role := data.RoleName("snapshot")
	size := c.local.Timestamp.Signed.Meta[role].Length
	expectedSha256, ok := c.local.Timestamp.Signed.Meta[role].Hashes["sha256"]
	if !ok {
		return fmt.Errorf("Sha256 is currently the only hash supported by this client. No Sha256 found for snapshot")
	}

	var download bool
	old := &data.Signed{}
	version := 0
	raw, err := c.cache.GetMeta(role, size)
	if raw == nil || err != nil {
		logrus.Debug("no snapshot in cache, must download")
		download = true
	} else {
		// file may have been tampered with on disk. Always check the hash!
		genHash := sha256.Sum256(raw)
		if !bytes.Equal(genHash[:], expectedSha256) {
			logrus.Debug("hash of snapshot in cache did not match expected hash, must download")
			download = true
		}
		err := json.Unmarshal(raw, old)
		if err == nil {
			snap, err := data.TimestampFromSigned(old)
			if err == nil {
				version = snap.Signed.Version
			} else {
				logrus.Debug("Could not parse Signed part of snapshot, must download")
				download = true
			}
		} else {
			logrus.Debug("Could not parse snapshot, must download")
			download = true
		}
	}
	var s *data.Signed
	if download {
		logrus.Debug("downloading new snapshot")
		raw, err = c.remote.GetMeta(role, size)
		if err != nil {
			return err
		}
		genHash := sha256.Sum256(raw)
		if !bytes.Equal(genHash[:], expectedSha256) {
			return fmt.Errorf("Retrieved snapshot did not verify against hash in timestamp.")
		}
		s = &data.Signed{}
		err = json.Unmarshal(raw, s)
		if err != nil {
			return err
		}
	} else {
		logrus.Debug("using cached snapshot")
		s = old
	}

	err = signed.Verify(s, role, version, c.keysDB)
	if err != nil {
		return err
	}
	logrus.Debug("successfully verified snapshot")
	c.local.SetSnapshot(s)
	if download {
		err = c.cache.SetMeta(role, raw)
		if err != nil {
			logrus.Errorf("Failed to write snapshot to local cache: %s", err.Error())
		}
	}
	return nil
}