magic-wormhole/src/wormhole/scripts/cmd_receive.py

from __future__ import print_function
import io, os, sys, json, binascii, six, tempfile, zipfile
from twisted.internet import reactor, defer
from twisted.internet.defer import inlineCallbacks, returnValue
from ..twisted.transcribe import Wormhole, WrongPasswordError
from ..twisted.transit import TransitReceiver
from ..errors import TransferError
from .progress import ProgressPrinter


APPID = u"lothar.com/wormhole/text-or-file-xfer"

class RespondError(Exception):
    def __init__(self, response):
        self.response = response

def receive_twisted_sync(args):
    # try to use twisted.internet.task.react(f) here (but it calls sys.exit
    # directly)
    d = defer.Deferred()
    # don't call receive_twisted() until after the reactor is running, so
    # that if it raises an exception synchronously, we won't stop the reactor
    # before it starts
    reactor.callLater(0, d.callback, None)
    d.addCallback(lambda _: receive_twisted(args))
    rc = []
    def _done(res):
        rc.extend([True, res])
        reactor.stop()
    def _err(f):
        rc.extend([False, f])
        reactor.stop()
    d.addCallbacks(_done, _err)
    reactor.run()
    if rc[0]:
        return rc[1]
    print(str(rc[1]))
    rc[1].raiseException()

def receive_twisted(args):
    return TwistedReceiver(args).go()


class TwistedReceiver:
    def __init__(self, args):
        assert isinstance(args.relay_url, type(u""))
        self.args = args

    def msg(self, *args, **kwargs):
        print(*args, file=self.args.stdout, **kwargs)

    # TODO: @handle_server_error
    @inlineCallbacks
    def go(self):
        tor_manager = None
        if self.args.tor:
            _start = self.args.timing.add_event("import TorManager")
            from ..twisted.tor_manager import TorManager
            self.args.timing.finish_event(_start)
            tor_manager = TorManager(reactor, timing=self.args.timing)
            # For now, block everything until Tor has started. Soon: launch
            # tor in parallel with everything else, make sure the TorManager
            # can lazy-provide an endpoint, and overlap the startup process
            # with the user handing off the wormhole code
            yield tor_manager.start()

        w = Wormhole(APPID, self.args.relay_url, tor_manager,
                     timing=self.args.timing)

        rc = yield self._go(w, tor_manager)
        yield w.close()
        returnValue(rc)

    @inlineCallbacks
    def _go(self, w, tor_manager):
        yield self.handle_code(w)
        verifier = yield w.get_verifier()
        self.show_verifier(verifier)
        them_d = yield self.get_data(w)
        try:
            if "message" in them_d:
                yield self.handle_text(them_d, w)
                returnValue(0)
            if "file" in them_d:
                f = self.handle_file(them_d)
                rp = yield self.establish_transit(w, them_d, tor_manager)
                yield self.transfer_data(rp, f)
                self.write_file(f)
                yield self.close_transit(rp)
            elif "directory" in them_d:
                f = self.handle_directory(them_d)
                rp = yield self.establish_transit(w, them_d, tor_manager)
                yield self.transfer_data(rp, f)
                self.write_directory(f)
                yield self.close_transit(rp)
            else:
                self.msg(u"I don't know what they're offering\n")
                self.msg(u"Offer details:", them_d)
                raise RespondError({"error": "unknown offer type"})
        except RespondError as r:
            data = json.dumps(r.response).encode("utf-8")
            yield w.send_data(data)
            returnValue(1)
        returnValue(0)

    @inlineCallbacks
    def handle_code(self, w):
        code = self.args.code
        if self.args.zeromode:
            assert not code
            code = u"0-"
        if not code:
            code = yield w.input_code("Enter receive wormhole code: ",
                                      self.args.code_length)
        yield w.set_code(code)

    def show_verifier(self, verifier):
        verifier_hex = binascii.hexlify(verifier).decode("ascii")
        if self.args.verify:
            self.msg(u"Verifier %s." % verifier_hex)

    @inlineCallbacks
    def get_data(self, w):
        try:
            them_bytes = yield w.get_data()
        except WrongPasswordError as e:
            raise TransferError(u"ERROR: " + e.explain())
        them_d = json.loads(them_bytes.decode("utf-8"))
        if "error" in them_d:
            raise TransferError(u"ERROR: " + them_d["error"])
        returnValue(them_d)

    @inlineCallbacks
    def handle_text(self, them_d, w):
        # we're receiving a text message
        self.msg(them_d["message"])
        data = json.dumps({"message_ack": "ok"}).encode("utf-8")
        yield w.send_data(data)

    def handle_file(self, them_d):
        file_data = them_d["file"]
        self.abs_destname = self.decide_destname("file",
                                                 file_data["filename"])
        self.xfersize = file_data["filesize"]

        self.msg(u"Receiving file (%d bytes) into: %s" %
                 (self.xfersize, os.path.basename(self.abs_destname)))
        self.ask_permission()
        tmp_destname = self.abs_destname + ".tmp"
        return open(tmp_destname, "wb")

    def handle_directory(self, them_d):
        file_data = them_d["directory"]
        zipmode = file_data["mode"]
        if zipmode != "zipfile/deflated":
            self.msg(u"Error: unknown directory-transfer mode '%s'" % (zipmode,))
            raise RespondError({"error": "unknown mode"})
        self.abs_destname = self.decide_destname("directory",
                                                 file_data["dirname"])
        self.xfersize = file_data["zipsize"]

        self.msg(u"Receiving directory (%d bytes) into: %s/" %
                 (self.xfersize, os.path.basename(self.abs_destname)))
        self.msg(u"%d files, %d bytes (uncompressed)" %
                 (file_data["numfiles"], file_data["numbytes"]))
        self.ask_permission()
        return tempfile.SpooledTemporaryFile()

    def decide_destname(self, mode, destname):
        # the basename() is intended to protect us against
        # "~/.ssh/authorized_keys" and other attacks
        destname = os.path.basename(destname)
        if self.args.output_file:
            destname = self.args.output_file # override
        abs_destname = os.path.join(self.args.cwd, destname)

        # get confirmation from the user before writing to the local directory
        if os.path.exists(abs_destname):
            self.msg(u"Error: refusing to overwrite existing %s %s" %
                     (mode, destname))
            raise RespondError({"error": "%s already exists" % mode})
        return abs_destname

    def ask_permission(self):
        _start = self.args.timing.add_event("permission", waiting="user")
        while True and not self.args.accept_file:
            ok = six.moves.input("ok? (y/n): ")
            if ok.lower().startswith("y"):
                break
            print(u"transfer rejected", file=sys.stderr)
            self.args.timing.finish_event(_start, answer="no")
            raise RespondError({"error": "transfer rejected"})
        self.args.timing.finish_event(_start, answer="yes")

    @inlineCallbacks
    def establish_transit(self, w, them_d, tor_manager):
        transit_key = w.derive_key(APPID+u"/transit-key")
        transit_receiver = TransitReceiver(self.args.transit_helper,
                                           no_listen=self.args.no_listen,
                                           tor_manager=tor_manager,
                                           timing=self.args.timing)
        transit_receiver.set_transit_key(transit_key)
        direct_hints = yield transit_receiver.get_direct_hints()
        relay_hints = yield transit_receiver.get_relay_hints()
        data = json.dumps({
            "file_ack": "ok",
            "transit": {
                "direct_connection_hints": direct_hints,
                "relay_connection_hints": relay_hints,
                },
            }).encode("utf-8")
        yield w.send_data(data)

        # now receive the rest of the owl
        tdata = them_d["transit"]
        transit_receiver.add_their_direct_hints(tdata["direct_connection_hints"])
        transit_receiver.add_their_relay_hints(tdata["relay_connection_hints"])
        record_pipe = yield transit_receiver.connect()
        returnValue(record_pipe)

    @inlineCallbacks
    def transfer_data(self, record_pipe, f):
        self.msg(u"Receiving (%s).." % record_pipe.describe())

        _start = self.args.timing.add_event("rx file")
        progress_stdout = self.args.stdout
        if self.args.hide_progress:
            progress_stdout = io.StringIO()
        progress = ProgressPrinter(self.xfersize, progress_stdout)

        progress.start()
        received = yield record_pipe.writeToFile(f, self.xfersize,
                                                 progress.update)
        progress.finish()
        self.args.timing.finish_event(_start)

        # except TransitError
        if received < self.xfersize:
            self.msg()
            self.msg(u"Connection dropped before full file received")
            self.msg(u"got %d bytes, wanted %d" % (received, self.xfersize))
            returnValue(1) # TODO: exit properly
        assert received == self.xfersize

    def write_file(self, f):
        tmp_name = f.name
        f.close()
        os.rename(tmp_name, self.abs_destname)
        self.msg(u"Received file written to %s" %
                 os.path.basename(self.abs_destname))

    def write_directory(self, f):
        self.msg(u"Unpacking zipfile..")
        _start = self.args.timing.add_event("unpack zip")
        with zipfile.ZipFile(f, "r", zipfile.ZIP_DEFLATED) as zf:
            zf.extractall(path=self.abs_destname)
            # extractall() appears to offer some protection against
            # malicious pathnames. For example, "/tmp/oops" and
            # "../tmp/oops" both do the same thing as the (safe)
            # "tmp/oops".
        self.msg(u"Received files written to %s/" %
                 os.path.basename(self.abs_destname))
        f.close()
        self.args.timing.finish_event(_start)

    @inlineCallbacks
    def close_transit(self, record_pipe):
        _start = self.args.timing.add_event("ack")
        yield record_pipe.send_record(b"ok\n")
        yield record_pipe.close()
        self.args.timing.finish_event(_start)