Implement dot stuffing for message bodies

lib/nntp/tiny/session.py

@@ -14,7 +14,8 @@ from nntp.tiny.db        import Database
 from nntp.tiny.response  import Response, ResponseCode
 from nntp.tiny.newsgroup import Newsgroup
 from nntp.tiny.user      import User, UserPermission
-from nntp.tiny.message   import Message, MessageRange, MessagePart
+from nntp.tiny.message   import (Message, MessageRange, MessagePart,
+                                 each_line)
 
 class SessionMode(enum.Enum):
     READER = 1
@@ -618,7 +619,13 @@ class Session():
             self.print('')
 
         if part is MessagePart.BODY or part is MessagePart.WHOLE:
-            self.print(message.body)
+            for line in each_line(message.body):
+                stripped = line.rstrip()
+
+                if stripped == '.':
+                    self.print('..')
+                else:
+                    self.print(stripped)
 
         return self.end()