Always 200 for OPTS UTF8 or OPTS UTF-8 ON (#676)

Author: vivodi

HISTORY.rst

@@ -3,6 +3,10 @@ Bug tracker at https://github.com/giampaolo/pyftpdlib/issues
 Version: 2.2.0 - XXXX-XX-XX
 ===========================
 
+**Bug fixes**
+
+* #676: Always return 200 for the ``OPTS UTF8`` and ``OPTS UTF-8 ON`` commands
+  to ensure correct FTP client compatibility when UTF-8 is supported.
 
 **Compatibility notes**
 

pyftpdlib/handlers/ftp/control.py

@@ -2224,22 +2224,24 @@ def ftp_OPTS(self, line):
                 raise ValueError("Invalid number of arguments")
             if " " in line:
                 cmd, arg = line.split(" ")
-                if ";" not in arg:
-                    raise ValueError("Invalid argument")
             else:
                 cmd, arg = line, ""
-            # actually the only command able to accept options is MLST
-            if cmd.upper() != "MLST" or "MLST" not in self.proto_cmds:
+            # the only commands able to accept options are MLST and UTF8
+            if cmd.upper() in ("UTF8", "UTF-8"):
+                self.respond('200 Always in UTF8 mode.')
+            elif cmd.upper() == "MLST" and "MLST" in self.proto_cmds:
+                if arg and ';' not in arg:
+                    raise ValueError('Invalid argument')
+                facts = [x.lower() for x in arg.split(";")]
+                self._current_facts = [
+                    x for x in facts if x in self._available_facts
+                ]
+                f = "".join([x + ";" for x in self._current_facts])
+                self.respond("200 MLST OPTS " + f)
+            else:
                 raise ValueError(f'Unsupported command "{cmd}"')
         except ValueError as err:
             self.respond(f"501 {err}.")
-        else:
-            facts = [x.lower() for x in arg.split(";")]
-            self._current_facts = [
-                x for x in facts if x in self._available_facts
-            ]
-            f = "".join([x + ";" for x in self._current_facts])
-            self.respond("200 MLST OPTS " + f)
 
     def ftp_NOOP(self, line):
         """Do nothing."""