Create exception hierarchy

packages/sshecret-sshd/src/sshecret_sshd/constants.py

@@ -14,3 +14,7 @@ ERROR_INFO_USERNAME_GONE = "Unexpected error: Username lost in transit."
 ERROR_INFO_REMOTE_IP_GONE = (
     "Unexpected error: Client connection details lost in transit."
 )
+ERROR_GENERIC_ERROR = "An unexpected error occured"
+ERROR_UNAUTHORIZED = "Denied due to policy or configuration"
+
+ERROR_REGISTRATION_NOT_ALLOWED = "Received registration command from unauthorized source."

packages/sshecret-sshd/src/sshecret_sshd/exceptions.py

@@ -0,0 +1,117 @@
+"""Exceptions.
+
+
+We define a hierarchy like this:
+
+- BaseSshecretSshError
+  - PolicyError
+  - CommandError
+"""
+
+from sshecret_sshd import constants
+
+
+class BaseSshecretSshError(Exception):
+    """Base exception class."""
+
+    default_message: str = constants.ERROR_GENERIC_ERROR
+
+    def __init__(self, message: str | None = None) -> None:
+        """Init error class."""
+        super().__init__(message or self.default_message)
+
+
+class BackendError(BaseSshecretSshError):
+    """Error communicating with the backend."""
+
+    default_message: str = constants.ERROR_BACKEND_ERROR
+
+    def __init__(
+        self, message: str | None = None, backend_error: str | None = None
+    ) -> None:
+        """Init error class."""
+
+        if not message:
+            message = self.default_message
+        if backend_error:
+            message += f" Upstream error: {backend_error}"
+
+        super().__init__(message)
+
+
+class PolicyError(BaseSshecretSshError):
+    """Error related to policy"""
+
+    default_message: str = constants.ERROR_UNAUTHORIZED
+
+
+class CommandError(BaseSshecretSshError):
+    """Errors related to commands."""
+
+    default_message: str = constants.ERROR_GENERIC_ERROR
+
+
+class SecretNotFoundError(CommandError):
+    """Secret was not found."""
+
+    default_message: str = constants.ERROR_NO_SECRET_FOUND
+
+
+class UnknownClientOrSecretError(CommandError):
+    """Client or secret was not found."""
+
+    default_message: str = constants.ERROR_UNKNOWN_CLIENT_OR_SECRET
+
+
+class NoCommandReceivedError(CommandError):
+    """Client or secret was not found."""
+
+    default_message: str = constants.ERROR_NO_COMMAND_RECEIVED
+
+
+class NoPublicKeyError(PolicyError):
+    """No public key received."""
+
+    default_message: str = constants.ERROR_NO_PUBLIC_KEY
+
+
+class InvalidPublicKeyType(PolicyError):
+    """Type of public key is not correct."""
+
+    default_message: str = constants.ERROR_INVALID_KEY_TYPE
+
+
+class UnknownCommandError(CommandError):
+    """Unknown command received."""
+
+    default_message: str = constants.ERROR_UNKNOWN_COMMAND
+
+
+class ProcessError(BaseSshecretSshError):
+    """Process related errors."""
+
+    default_message: str = constants.ERROR_GENERIC_ERROR
+
+
+class NoBackendError(ProcessError):
+    """Error related to backend object resolution."""
+
+    default_message: str = constants.ERROR_INFO_BACKEND_GONE
+
+
+class NoUsernameError(ProcessError):
+    """Error related to username resolution."""
+
+    default_message: str = constants.ERROR_INFO_USERNAME_GONE
+
+
+class NoRemoteIpError(ProcessError):
+    """Error related to remote_ip resolution."""
+
+    default_message: str = constants.ERROR_INFO_REMOTE_IP_GONE
+
+
+class NoClientError(ProcessError):
+    """Error related to client resolution."""
+
+    default_message: str = constants.ERROR_UNKNOWN_CLIENT_OR_SECRET