transit: provide encrypted record-pipe, use it for file-xfer
This commit is contained in:
Brian Warner
parent
8b3e5836ee
commit
fcd2678dfd
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@ -1,6 +1,7 @@
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from __future__ import print_function
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import re, time, threading, socket, SocketServer
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from binascii import hexlify
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from binascii import hexlify, unhexlify
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from nacl.secret import SecretBox
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from ..util import ipaddrs
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from ..util.hkdf import HKDF
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from ..const import TRANSIT_RELAY
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@ -212,6 +213,62 @@ class MyTCPServer(SocketServer.TCPServer):
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t.start()
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class TransitClosed(TransitError):
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pass
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class BadNonce(TransitError):
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pass
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class ReceiveBuffer:
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def __init__(self, skt):
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self.skt = skt
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self.buf = b""
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def read(self, count):
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while len(self.buf) < count:
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more = self.skt.recv(4096)
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if not more:
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raise TransitClosed
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self.buf += more
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rc = self.buf[:count]
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self.buf = self.buf[count:]
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return rc
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class RecordPipe:
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def __init__(self, skt, send_key, receive_key):
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self.skt = skt
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self.send_box = SecretBox(send_key)
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self.send_nonce = 0
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self.receive_buf = ReceiveBuffer(self.skt)
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self.receive_box = SecretBox(receive_key)
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self.next_receive_nonce = 0
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def send_record(self, record):
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assert SecretBox.NONCE_SIZE == 24
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assert self.send_nonce < 2**(8*24)
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assert len(record) < 2**(8*4)
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nonce = unhexlify("%048x" % self.send_nonce) # big-endian
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self.send_nonce += 1
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encrypted = self.send_box.encrypt(record, nonce)
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length = unhexlify("%08x" % len(encrypted)) # always 4 bytes long
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send_to(self.skt, length)
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send_to(self.skt, encrypted)
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def receive_record(self):
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length_buf = self.receive_buf.read(4)
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length = int(hexlify(length_buf), 16)
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encrypted = self.receive_buf.read(length)
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nonce_buf = encrypted[:SecretBox.NONCE_SIZE] # assume it's prepended
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nonce = int(hexlify(nonce_buf), 16)
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if nonce != self.next_receive_nonce:
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raise BadNonce("received out-of-order record")
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self.next_receive_nonce += 1
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record = self.receive_box.decrypt(encrypted)
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return record
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def close(self):
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self.skt.close()
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class Common:
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def __init__(self):
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self.winning = threading.Event()
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@ -253,6 +310,22 @@ class Common:
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else:
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return build_sender_handshake(self._transit_key) + "go\n"
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def _sender_record_key(self):
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if self.is_sender:
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return HKDF(self._transit_key, SecretBox.KEY_SIZE,
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CTXinfo=b"transit_record_sender_key")
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else:
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return HKDF(self._transit_key, SecretBox.KEY_SIZE,
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CTXinfo=b"transit_record_receiver_key")
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def _receiver_record_key(self):
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if self.is_sender:
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return HKDF(self._transit_key, SecretBox.KEY_SIZE,
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CTXinfo=b"transit_record_receiver_key")
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else:
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return HKDF(self._transit_key, SecretBox.KEY_SIZE,
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CTXinfo=b"transit_record_sender_key")
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def set_transit_key(self, key):
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# This _have_transit_key condition/lock protects us against the race
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# where the sender knows the hints and the key, and connects to the
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@ -288,7 +361,7 @@ class Common:
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for hint in self._their_relay_hints:
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self._start_connector(hint, is_relay=True)
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def establish_connection(self):
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def establish_socket(self):
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start = time.time()
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self.winning_skt = None
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self.winning_skt_description = None
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@ -340,6 +413,11 @@ class Common:
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send_to(skt, "nevermind\n")
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skt.close()
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def connect(self):
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skt = self.establish_socket()
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return RecordPipe(skt, self._sender_record_key(),
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self._receiver_record_key())
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class TransitSender(Common):
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is_sender = True
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@ -1,8 +1,7 @@
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from __future__ import print_function
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import sys, os, json
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from nacl.secret import SecretBox
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from wormhole.blocking.transcribe import Receiver, WrongPasswordError
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from wormhole.blocking.transit import TransitReceiver
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from wormhole.blocking.transit import TransitReceiver, TransitError
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from .progress import start_progress, update_progress, finish_progress
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APPID = "lothar.com/wormhole/file-xfer"
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@ -28,10 +27,8 @@ def receive_file(so):
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#print("their data: %r" % (data,))
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file_data = data["file"]
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xfer_key = r.derive_key(APPID+"/xfer-key", SecretBox.KEY_SIZE)
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filename = os.path.basename(file_data["filename"]) # unicode
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filesize = file_data["filesize"]
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encrypted_filesize = filesize + SecretBox.NONCE_SIZE+16
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# now receive the rest of the owl
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tdata = data["transit"]
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@ -39,46 +36,47 @@ def receive_file(so):
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transit_receiver.set_transit_key(transit_key)
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transit_receiver.add_their_direct_hints(tdata["direct_connection_hints"])
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transit_receiver.add_their_relay_hints(tdata["relay_connection_hints"])
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skt = transit_receiver.establish_connection()
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record_pipe = transit_receiver.connect()
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print("Receiving %d bytes for '%s' (%s).." % (filesize, filename,
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transit_receiver.describe()))
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encrypted = b""
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next_update = start_progress(encrypted_filesize)
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while len(encrypted) < encrypted_filesize:
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more = skt.recv(encrypted_filesize - len(encrypted))
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if not more:
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print()
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print("Connection dropped before full file received")
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print("got %d bytes, wanted %d" % (len(encrypted), encrypted_filesize))
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return 1
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encrypted += more
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next_update = update_progress(next_update, len(encrypted),
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encrypted_filesize)
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finish_progress(encrypted_filesize)
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assert len(encrypted) == encrypted_filesize
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print("Decrypting..")
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decrypted = SecretBox(xfer_key).decrypt(encrypted)
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# only write to the current directory, and never overwrite anything
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here = os.path.abspath(os.getcwd())
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target = os.path.abspath(os.path.join(here, filename))
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if os.path.dirname(target) != here:
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print("Error: suggested filename (%s) would be outside current directory"
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% (filename,))
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skt.send("bad filename\n")
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skt.close()
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record_pipe.send_record("bad filename\n")
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record_pipe.close()
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return 1
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if os.path.exists(target):
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print("Error: refusing to overwrite existing file %s" % (filename,))
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skt.send("file already exists\n")
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skt.close()
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record_pipe.send_record("file already exists\n")
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record_pipe.close()
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return 1
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with open(target, "wb") as f:
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f.write(decrypted)
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tmp = target + ".tmp"
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with open(tmp, "wb") as f:
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received = 0
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next_update = start_progress(filesize)
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while received < filesize:
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try:
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plaintext = record_pipe.receive_record()
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except TransitError:
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print()
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print("Connection dropped before full file received")
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print("got %d bytes, wanted %d" % (received, filesize))
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return 1
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f.write(plaintext)
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received += len(plaintext)
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next_update = update_progress(next_update, received, filesize)
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finish_progress(filesize)
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assert received == filesize
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os.rename(tmp, target)
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print("Received file written to %s" % filename)
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skt.send("ok\n")
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skt.close()
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record_pipe.send_record("ok\n")
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record_pipe.close()
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return 0
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@ -1,6 +1,5 @@
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from __future__ import print_function
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import os, sys, json
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from nacl.secret import SecretBox
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from wormhole.blocking.transcribe import Initiator, WrongPasswordError
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from wormhole.blocking.transit import TransitSender
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from .progress import start_progress, update_progress, finish_progress
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@ -37,36 +36,30 @@ def send_file(so):
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return 1
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them_d = json.loads(them_bytes.decode("utf-8"))
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#print("them: %r" % (them_d,))
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xfer_key = i.derive_key(APPID+"/xfer-key", SecretBox.KEY_SIZE)
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print("Encrypting %d bytes.." % filesize)
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box = SecretBox(xfer_key)
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with open(filename, "rb") as f:
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plaintext = f.read()
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nonce = os.urandom(SecretBox.NONCE_SIZE)
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encrypted = box.encrypt(plaintext, nonce)
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tdata = them_d["transit"]
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transit_key = i.derive_key(APPID+"/transit-key")
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transit_sender.set_transit_key(transit_key)
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transit_sender.add_their_direct_hints(tdata["direct_connection_hints"])
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transit_sender.add_their_relay_hints(tdata["relay_connection_hints"])
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skt = transit_sender.establish_connection()
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record_pipe = transit_sender.connect()
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print("Sending (%s).." % transit_sender.describe())
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sent = 0
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next_update = start_progress(len(encrypted))
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while sent < len(encrypted):
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sent += skt.send(encrypted[sent:])
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next_update = update_progress(next_update, sent, len(encrypted))
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finish_progress(len(encrypted))
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CHUNKSIZE = 64*1024
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with open(filename, "rb") as f:
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sent = 0
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next_update = start_progress(filesize)
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while sent < filesize:
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plaintext = f.read(CHUNKSIZE)
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record_pipe.send_record(plaintext)
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sent += len(plaintext)
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next_update = update_progress(next_update, sent, filesize)
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finish_progress(filesize)
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print("File sent.. waiting for confirmation")
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# ack is a short newline-terminated string, followed by socket close. A long
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# read is probably good enough.
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ack = skt.recv(300)
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ack = record_pipe.receive_record()
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if ack == "ok\n":
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print("Confirmation received. Transfer complete.")
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return 0
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