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blocking: finish alignment

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This commit is contained in:
Brian Warner 2015-07-24 17:28:55 -07:00
parent 2ad65e13fe
commit d8ca850d1a
1 changed files with 29 additions and 26 deletions
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37
src/wormhole/blocking/transcribe.py
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@ -97,13 +97,6 @@ class Wormhole:
r.raise_for_status() r.raise_for_status()
return r.json() return r.json()
def _post_message(self, url, msg):
# TODO: retry on failure, with exponential backoff. We're guarding
# against the rendezvous server being temporarily offline.
if not isinstance(msg, type(b"")): raise UsageError(type(msg))
resp = self._post_json(url, {"message": hexlify(msg).decode("ascii")})
return resp["messages"] # other_msgs
def _allocate_channel(self): def _allocate_channel(self):
r = requests.post(self.relay + "allocate/%s" % self.side) r = requests.post(self.relay + "allocate/%s" % self.side)
r.raise_for_status() r.raise_for_status()
@ -155,6 +148,13 @@ class Wormhole:
idB=self.appid+":SymmetricB") idB=self.appid+":SymmetricB")
self.msg1 = self.sp.start() self.msg1 = self.sp.start()
def _post_message(self, url, msg):
# TODO: retry on failure, with exponential backoff. We're guarding
# against the rendezvous server being temporarily offline.
if not isinstance(msg, type(b"")): raise UsageError(type(msg))
resp = self._post_json(url, {"message": hexlify(msg).decode("ascii")})
return resp["messages"] # other_msgs
def _get_message(self, old_msgs, verb, msgnum): def _get_message(self, old_msgs, verb, msgnum):
# For now, server errors cause the client to fail. TODO: don't. This # For now, server errors cause the client to fail. TODO: don't. This
# will require changing the client to re-post messages when the # will require changing the client to re-post messages when the
@ -208,31 +208,34 @@ class Wormhole:
return self.verifier return self.verifier
def get_data(self, outbound_data): def get_data(self, outbound_data):
# only call this once
if self.code is None: raise UsageError if self.code is None: raise UsageError
if self.channel_id is None: raise UsageError if self.channel_id is None: raise UsageError
try:
self._get_key() self._get_key()
return self._get_data2(outbound_data)
finally:
self._deallocate()
def _get_data2(self, outbound_data):
# Without predefined roles, we can't derive predictably unique keys # Without predefined roles, we can't derive predictably unique keys
# for each side, so we use the same key for both. We use random # for each side, so we use the same key for both. We use random
# nonces to keep the messages distinct, and check for reflection. # nonces to keep the messages distinct, and check for reflection.
try:
data_key = self.derive_key(b"data-key") data_key = self.derive_key(b"data-key")
outbound_encrypted = self._encrypt_data(data_key, outbound_data) outbound_encrypted = self._encrypt_data(data_key, outbound_data)
old_msgs = self._post_message(self._url("post", "data"), msgs = self._post_message(self._url("post", "data"), outbound_encrypted)
outbound_encrypted)
inbound_encrypted = self._get_message(old_msgs, "poll", "data") inbound_encrypted = self._get_message(msgs, "poll", "data")
if inbound_encrypted == outbound_encrypted: if inbound_encrypted == outbound_encrypted:
raise ReflectionAttack raise ReflectionAttack
try: try:
inbound_data = self._decrypt_data(data_key, inbound_encrypted) inbound_data = self._decrypt_data(data_key, inbound_encrypted)
return inbound_data
except CryptoError: except CryptoError:
raise WrongPasswordError raise WrongPasswordError
finally:
self._deallocate()
return inbound_data
def _deallocate(self): def _deallocate(self):
r = requests.post(self._url("deallocate")) # only try once, no retries
r.raise_for_status() requests.post(self._url("deallocate"))
# ignore POST failure, don't call r.raise_for_status()