pybind/mgr/smb: add validation.py for generic module validation funcs

Signed-off-by: John Mulligan <jmulligan@redhat.com>

diff --git a/src/pybind/mgr/smb/validation.py b/src/pybind/mgr/smb/validation.py
new file mode 100644 (file)
index 0000000..3e04650
--- /dev/null
+++ b/src/pybind/mgr/smb/validation.py
@@ -0,0 +1,62 @@
+import posixpath
+import re
+
+# Initially, this regex is pretty restrictive.  But I (JJM) find that
+# starting out more restricitive is better than not because it's generally
+# easier to relax strict rules then discover someone relies on lax rules
+# that fail somewhere and now you've got backwards-compatibilty issues
+# to worry about.
+#
+# The names are valid dns fragments as well since the cluster_id can be
+# combined with the hostname for a virtual hostname for the container.
+_name_re = re.compile('^[a-zA-Z0-9]($|[a-zA-Z0-9-]{,16}[a-zA-Z0-9]$)')
+
+# We might want to open up share names to non-special unicode chars too.
+# but as above it's easier to start strict.
+_share_re = re.compile('^[a-zA-Z0-9_][a-zA-Z0-9. _-]{,63}$')
+
+
+def valid_id(value: str) -> bool:
+    """Return true if value is a valid (cluster|share|etc) ID."""
+    return bool(_name_re.match(value))
+
+
+def check_id(value: str) -> None:
+    """Raise ValueError if value is not a valid ID."""
+    if not valid_id(value):
+        raise ValueError(f"{value:!r} is not a valid ID")
+
+
+def valid_share_name(value: str) -> bool:
+    """Return true if value is a valid share name."""
+    return bool(_share_re.match(value))
+
+
+def check_share_name(value: str) -> None:
+    """Raise ValueError if value is not a valid share name."""
+    if not valid_share_name(value):
+        raise ValueError(f"{value:!r} is not a valid share name")
+
+
+# alias for normpath so other smb libs can just import validation module
+normalize_path = posixpath.normpath
+
+
+def valid_path(value: str) -> bool:
+    """Return true if value is a valid path for a share."""
+    path = normalize_path(value)
+    # ensure that post-normalization there are no relative path elements or
+    # empty segments
+    if path == '/':
+        # special case / to refer to the root of the volume/subvolume.
+        # it is always valid.
+        return True
+    return not any(
+        p in ('.', '..', '') for p in path.lstrip('/').split(posixpath.sep)
+    )
+
+
+def check_path(value: str) -> None:
+    """Raise ValueError if value is not a valid share path."""
+    if not valid_path(value):
+        raise ValueError(f'{value!r} is not a valid share path')