[#119] frostfsid: Add 'GetValueForSubjectKey'

Signed-off-by: Alexander Chuprov <a.chuprov@yadro.com>

frostfsid/config.yml

@@ -7,6 +7,7 @@ safemethods:
   - "getGroupByName"
   - "getNamespace"
   - "getNamespaceExtended"
+  - "getValueForSubjectKey"
   - "getSubject"
   - "getSubjectExtended"
   - "getSubjectByKey"

frostfsid/frostfsid_contract.go

@@ -472,6 +472,30 @@ func GetSubjectKeyByName(ns, name string) interop.PublicKey {
 	return subjKey
 }
 
+// GetValueForSubjectKey GetSubjectKey returns the value associated with the key for the subject.
+func GetValueForSubjectKey(addr interop.Hash160, name string) string {
+	if len(addr) != interop.Hash160Len {
+		panic("incorrect address length")
+	}
+
+	ctx := storage.GetReadOnlyContext()
+	sKey := subjectKeyFromAddr(addr)
+	data := storage.Get(ctx, sKey).([]byte)
+	if data == nil {
+		return ""
+	}
+
+	sbj := std.Deserialize(data).(Subject)
+
+	for k, v := range sbj.KV {
+		if k == name {
+			return v
+		}
+	}
+
+	return ""
+}
+
 func ListSubjects() iterator.Iterator {
 	ctx := storage.GetReadOnlyContext()
 	return storage.Find(ctx, []byte{subjectKeysPrefix}, storage.KeysOnly|storage.RemovePrefix)

rpcclient/frostfsid/client.go

@@ -227,6 +227,11 @@ func (c *ContractReader) GetSubjectKeyByName(ns string, name string) (*keys.Publ
 	return unwrap.PublicKey(c.invoker.Call(c.hash, "getSubjectKeyByName", ns, name))
 }
 
+// GetValueForSubjectKey invokes `getValueForSubjectKey` method of contract.
+func (c *ContractReader) GetValueForSubjectKey(addr util.Uint160, name string) (string, error) {
+	return unwrap.UTF8String(c.invoker.Call(c.hash, "getValueForSubjectKey", addr, name))
+}
+
 // ListGroupSubjects invokes `listGroupSubjects` method of contract.
 func (c *ContractReader) ListGroupSubjects(ns string, groupID *big.Int) (uuid.UUID, result.Iterator, error) {
 	return unwrap.SessionIterator(c.invoker.Call(c.hash, "listGroupSubjects", ns, groupID))