only allow code to be set once

src/wormhole/_boss.py

@@ -17,7 +17,8 @@ from ._rendezvous import RendezvousConnector
 from ._lister import Lister
 from ._code import Code
 from ._terminator import Terminator
-from .errors import ServerError, LonelyError, WrongPasswordError, KeyFormatError
+from .errors import (ServerError, LonelyError, WrongPasswordError,
+                     KeyFormatError, OnlyOneCodeError)
 from .util import bytes_to_dict
 
 @attrs
@@ -62,6 +63,7 @@ class Boss(object):
         self._C.wire(self, self._RC, self._L)
         self._T.wire(self, self._RC, self._N, self._M)
 
+        self._did_start_code = False
         self._next_tx_phase = 0
         self._next_rx_phase = 0
         self._rx_phases = {} # phase -> plaintext
@@ -113,12 +115,21 @@ class Boss(object):
     # Wormhole only knows about this Boss instance, and everything else is
     # hidden away).
     def input_code(self, stdio):
+        if self._did_start_code:
+            raise OnlyOneCodeError()
+        self._did_start_code = True
         self._C.input_code(stdio)
     def allocate_code(self, code_length):
+        if self._did_start_code:
+            raise OnlyOneCodeError()
+        self._did_start_code = True
         self._C.allocate_code(code_length)
     def set_code(self, code):
         if ' ' in code:
             raise KeyFormatError("code (%s) contains spaces." % code)
+        if self._did_start_code:
+            raise OnlyOneCodeError()
+        self._did_start_code = True
         self._C.set_code(code)
 
     @m.input()

src/wormhole/errors.py

@@ -54,6 +54,9 @@ class NoTorError(WormholeError):
 class NoKeyError(WormholeError):
     """w.derive_key() was called before got_verifier() fired"""
 
+class OnlyOneCodeError(WormholeError):
+    """Only one w.generate_code/w.set_code/w.type_code may be called"""
+
 class WormholeClosed(Exception):
     """Deferred-returning API calls errback with WormholeClosed if the
     wormhole was already closed, or if it closes before a real result can be

src/wormhole/test/test_wormhole.py

@@ -8,7 +8,8 @@ from twisted.internet.defer import Deferred, gatherResults, inlineCallbacks
 from .common import ServerBase
 from .. import wormhole, _rendezvous
 from ..errors import (WrongPasswordError, WelcomeError, InternalError,
-                      KeyFormatError, WormholeClosed, LonelyError)
+                      KeyFormatError, WormholeClosed, LonelyError,
+                      NoKeyError, OnlyOneCodeError)
 from spake2 import SPAKE2_Symmetric
 from ..timing import DebugTiming
 from ..util import (bytes_to_dict, dict_to_bytes,
@@ -979,23 +980,24 @@ class MessageDoubler(_rendezvous.RendezvousConnector):
 
 class Errors(ServerBase, unittest.TestCase):
     @inlineCallbacks
-    def test_codes_1(self):
+    def test_derive_key_early(self):
         w = wormhole.create(APPID, self.relayurl, reactor)
         # definitely too early
-        self.assertRaises(InternalError, w.derive_key, "purpose", 12)
-
-        w.set_code("123-purple-elephant")
-        # code can only be set once
-        self.assertRaises(InternalError, w.set_code, "123-nope")
-        yield self.assertFailure(w.when_code(), InternalError)
-        yield self.assertFailure(w.input_code(), InternalError)
-        yield w.close()
+        self.assertRaises(NoKeyError, w.derive_key, "purpose", 12)
+        yield self.assertFailure(w.close(), LonelyError)
 
     @inlineCallbacks
-    def test_codes_2(self):
+    def test_multiple_set_code(self):
         w = wormhole.create(APPID, self.relayurl, reactor)
+        w.set_code("123-purple-elephant")
+        # code can only be set once
+        self.assertRaises(OnlyOneCodeError, w.set_code, "123-nope")
+        yield self.assertFailure(w.close(), LonelyError)
+
+    @inlineCallbacks
+    def test_allocate_and_set_code(self):
+        w = wormhole.create(APPID, self.relayurl, reactor)
+        w.allocate_code()
         yield w.when_code()
-        self.assertRaises(InternalError, w.set_code, "123-nope")
-        yield self.assertFailure(w.when_code(), InternalError)
-        yield self.assertFailure(w.input_code(), InternalError)
-        yield w.close()
+        self.assertRaises(OnlyOneCodeError, w.set_code, "123-nope")
+        yield self.assertFailure(w.close(), LonelyError)