// downloadTargets is responsible for downloading any targets file
// including delegates roles.
func (c *Client) downloadTargets(role string) error {
role = data.RoleName(role) // this will really only do something for base targets role
if c.local.Snapshot == nil {
return ErrMissingMeta{role: role}
}
snap := c.local.Snapshot.Signed
root := c.local.Root.Signed
r := c.keysDB.GetRole(role)
if r == nil {
return fmt.Errorf("Invalid role: %s", role)
}
keyIDs := r.KeyIDs
s, err := c.getTargetsFile(role, keyIDs, snap.Meta, root.ConsistentSnapshot, r.Threshold)
if err != nil {
logrus.Error("Error getting targets file:", err)
return err
}
t, err := data.TargetsFromSigned(s)
if err != nil {
return err
}
err = c.local.SetTargets(role, t)
if err != nil {
return err
}
return nil
}
// SetTargets parses the Signed object into a SignedTargets object,
// reads the delegated roles and keys into the KeyDB, and sets the
// SignedTargets object agaist the role in the TufRepo.Targets map.
func (tr *TufRepo) SetTargets(role string, s *data.Signed) error {
t, err := data.TargetsFromSigned(s)
if err != nil {
return err
}
for _, k := range t.Signed.Delegations.Keys {
tr.keysDB.AddKey(k)
}
for _, r := range t.Signed.Delegations.Roles {
tr.keysDB.AddRole(r)
}
tr.Targets[role] = t
return nil
}
func validateTargets(role string, roles map[string]storage.MetaUpdate, kdb *keys.KeyDB) (*data.SignedTargets, error) {
// TODO: when delegations are being validated, validate parent
// role exists for any delegation
s := &data.Signed{}
err := json.Unmarshal(roles[role].Data, s)
if err != nil {
return nil, fmt.Errorf("could not parse %s", role)
}
// version specifically gets validated when writing to store to
// better handle race conditions there.
if err := signed.Verify(s, role, 0, kdb); err != nil {
return nil, err
}
t, err := data.TargetsFromSigned(s)
if err != nil {
return nil, err
}
if !data.ValidTUFType(t.Signed.Type, data.CanonicalTargetsRole) {
return nil, fmt.Errorf("%s has wrong type", role)
}
return t, nil
}
func (c Client) getTargetsFile(role string, keyIDs []string, snapshotMeta data.Files, consistent bool, threshold int) (*data.Signed, error) {
// require role exists in snapshots
roleMeta, ok := snapshotMeta[role]
if !ok {
return nil, ErrMissingMeta{role: role}
}
expectedSha256, ok := snapshotMeta[role].Hashes["sha256"]
if !ok {
return nil, ErrMissingMeta{role: role}
}
// try to get meta file from content addressed cache
var download bool
old := &data.Signed{}
version := 0
raw, err := c.cache.GetMeta(role, roleMeta.Length)
if err != nil || raw == nil {
logrus.Debugf("Couldn't not find cached %s, must download", role)
download = true
} else {
// file may have been tampered with on disk. Always check the hash!
genHash := sha256.Sum256(raw)
if !bytes.Equal(genHash[:], expectedSha256) {
download = true
}
err := json.Unmarshal(raw, old)
if err == nil {
targ, err := data.TargetsFromSigned(old)
if err == nil {
version = targ.Signed.Version
} else {
download = true
}
} else {
download = true
}
}
size := snapshotMeta[role].Length
var s *data.Signed
if download {
rolePath, err := c.RoleTargetsPath(role, hex.EncodeToString(expectedSha256), consistent)
if err != nil {
return nil, err
}
raw, s, err = c.downloadSigned(rolePath, size, expectedSha256)
if err != nil {
return nil, err
}
} else {
logrus.Debug("using cached ", role)
s = old
}
err = signed.Verify(s, role, version, c.keysDB)
if err != nil {
return nil, err
}
logrus.Debugf("successfully verified %s", role)
if download {
// if we error when setting meta, we should continue.
err = c.cache.SetMeta(role, raw)
if err != nil {
logrus.Errorf("Failed to write snapshot to local cache: %s", err.Error())
}
}
return s, nil
}