Force engine id discovery to use empty user name for MikroTik RouterO…

…S compatibility

src/gufo/snmp/_fast.pyi

@@ -136,6 +136,7 @@ class SnmpV3ClientSocket(object):
     ) -> None: ...
     def set_keys(
         self: "SnmpV3ClientSocket",
+        user_name: str,
         auth_alg: int,
         auth_key: bytes,
         priv_alg: int,

src/gufo/snmp/async_client/client.py

@@ -119,6 +119,7 @@ def __init__(
             if not engine_id:
                 # Defer authentication until engine id is discovered
                 self._deferred_user = user
+                user = User.default()
             self._sock = SnmpV3ClientSocket(
                 f"{addr}:{port}",
                 engine_id if engine_id else b"",
@@ -328,6 +329,7 @@ async def refresh(self: "SnmpSession") -> None:
             )
             # Set and localize actual keys
             self._sock.set_keys(
+                self._deferred_user.name,
                 self._deferred_user.get_auth_alg(),
                 self._deferred_user.get_auth_key(),
                 self._deferred_user.get_priv_alg(),

src/gufo/snmp/sync_client/client.py

@@ -121,6 +121,7 @@ def __init__(
             if not engine_id:
                 # Defer authentication until engine id is discovered
                 self._deferred_user = user
+                user = User.default()
             self._sock = SnmpV3ClientSocket(
                 f"{addr}:{port}",
                 engine_id if engine_id else b"",
@@ -313,6 +314,7 @@ def refresh(self: "SnmpSession") -> None:
             self._sock.sync_refresh()
             # Set and localize actual keys
             self._sock.set_keys(
+                self._deferred_user.name,
                 self._deferred_user.get_auth_alg(),
                 self._deferred_user.get_auth_key(),
                 self._deferred_user.get_priv_alg(),

src/gufo/snmp/user.py

@@ -243,6 +243,16 @@ def __init__(
         ):
             self.priv_key._pad(self.auth_key.KEY_LENGTH)
 
+    @classmethod
+    def default(cls: Type["User"]) -> "User":
+        """
+        Default user without name and keys.
+
+        Returns:
+            Default user instance.
+        """
+        return User(name="")
+
     def require_auth(self: "User") -> bool:
         """
         Chech if user requires authentication.

src/socket/v3.rs

@@ -89,11 +89,14 @@ impl SnmpV3ClientSocket {
     /// Change keys
     fn set_keys(
         &mut self,
+        user_name: String,
         auth_alg: u8,
         auth_key: &[u8],
         priv_alg: u8,
         priv_key: &[u8],
     ) -> PyResult<()> {
+        // Replace user
+        self.user_name = user_name;
         // Auth key
         let mut auth = AuthKey::new(auth_alg)?;
         auth.as_key_type(auth_alg, auth_key, &self.engine_id)?;