# -*- test-case-name: twisted.conch.test.test_filetransfer -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE file for details.

"""
Tests for L{twisted.conch.ssh.filetransfer}.
"""


import os
import re
import struct
from unittest import skipIf

from twisted.internet import defer
from twisted.internet.error import ConnectionLost
from twisted.protocols import loopback
from twisted.python import components
from twisted.python.compat import _PY37PLUS
from twisted.python.filepath import FilePath
from twisted.trial.unittest import TestCase

try:
    from twisted.conch import unix as _unix
except ImportError:
    unix = None
else:
    unix = _unix

try:
    from twisted.conch.unix import (
        SFTPServerForUnixConchUser as _SFTPServerForUnixConchUser,
    )
except ImportError:
    SFTPServerForUnixConchUser = None
else:
    SFTPServerForUnixConchUser = _SFTPServerForUnixConchUser

try:
    import cryptography as _cryptography
except ImportError:
    cryptography = None
else:
    cryptography = _cryptography

try:
    from twisted.conch.avatar import ConchUser as _ConchUser
except ImportError:
    ConchUser = object
else:
    ConchUser = _ConchUser  # type: ignore[misc]

try:
    from twisted.conch.ssh import common, connection, filetransfer, session
except ImportError:
    pass


class TestAvatar(ConchUser):
    def __init__(self):
        ConchUser.__init__(self)
        self.channelLookup[b"session"] = session.SSHSession
        self.subsystemLookup[b"sftp"] = filetransfer.FileTransferServer

    def _runAsUser(self, f, *args, **kw):
        try:
            f = iter(f)
        except TypeError:
            f = [(f, args, kw)]
        for i in f:
            func = i[0]
            args = len(i) > 1 and i[1] or ()
            kw = len(i) > 2 and i[2] or {}
            r = func(*args, **kw)
        return r


class FileTransferTestAvatar(TestAvatar):
    def __init__(self, homeDir):
        TestAvatar.__init__(self)
        self.homeDir = homeDir

    def getHomeDir(self):
        return FilePath(os.getcwd()).preauthChild(self.homeDir.path)


class ConchSessionForTestAvatar:
    def __init__(self, avatar):
        self.avatar = avatar


if SFTPServerForUnixConchUser is None:
    # unix should either be a fully working module, or None.  I'm not sure
    # how this happens, but on win32 it does.  Try to cope.  --spiv.
    import warnings

    warnings.warn(
        (
            "twisted.conch.unix imported %r, "
            "but doesn't define SFTPServerForUnixConchUser'"
        )
        % (unix,)
    )
else:

    class FileTransferForTestAvatar(SFTPServerForUnixConchUser):  # type: ignore[misc,valid-type]
        def gotVersion(self, version, otherExt):
            return {b"conchTest": b"ext data"}

        def extendedRequest(self, extName, extData):
            if extName == b"testExtendedRequest":
                return b"bar"
            raise NotImplementedError

    components.registerAdapter(
        FileTransferForTestAvatar, TestAvatar, filetransfer.ISFTPServer
    )


class SFTPTestBase(TestCase):
    def setUp(self):
        self.testDir = FilePath(self.mktemp())
        # Give the testDir another level so we can safely "cd .." from it in
        # tests.
        self.testDir = self.testDir.child("extra")
        self.testDir.child("testDirectory").makedirs(True)

        with self.testDir.child("testfile1").open(mode="wb") as f:
            f.write(b"a" * 10 + b"b" * 10)
            with open("/dev/urandom", "rb") as f2:
                f.write(f2.read(1024 * 64))  # random data
        self.testDir.child("testfile1").chmod(0o644)
        with self.testDir.child("testRemoveFile").open(mode="wb") as f:
            f.write(b"a")
        with self.testDir.child("testRenameFile").open(mode="wb") as f:
            f.write(b"a")
        with self.testDir.child(".testHiddenFile").open(mode="wb") as f:
            f.write(b"a")


@skipIf(not unix, "can't run on non-posix computers")
class OurServerOurClientTests(SFTPTestBase):
    def setUp(self):
        SFTPTestBase.setUp(self)

        self.avatar = FileTransferTestAvatar(self.testDir)
        self.server = filetransfer.FileTransferServer(avatar=self.avatar)
        clientTransport = loopback.LoopbackRelay(self.server)

        self.client = filetransfer.FileTransferClient()
        self._serverVersion = None
        self._extData = None

        def _(serverVersion, extData):
            self._serverVersion = serverVersion
            self._extData = extData

        self.client.gotServerVersion = _
        serverTransport = loopback.LoopbackRelay(self.client)
        self.client.makeConnection(clientTransport)
        self.server.makeConnection(serverTransport)

        self.clientTransport = clientTransport
        self.serverTransport = serverTransport

        self._emptyBuffers()

    def _emptyBuffers(self):
        while self.serverTransport.buffer or self.clientTransport.buffer:
            self.serverTransport.clearBuffer()
            self.clientTransport.clearBuffer()

    def tearDown(self):
        self.serverTransport.loseConnection()
        self.clientTransport.loseConnection()
        self.serverTransport.clearBuffer()
        self.clientTransport.clearBuffer()

    def test_serverVersion(self):
        self.assertEqual(self._serverVersion, 3)
        self.assertEqual(self._extData, {b"conchTest": b"ext data"})

    def test_interface_implementation(self):
        """
        It implements the ISFTPServer interface.
        """
        self.assertTrue(
            filetransfer.ISFTPServer.providedBy(self.server.client),
            f"ISFTPServer not provided by {self.server.client!r}",
        )

    def test_openedFileClosedWithConnection(self):
        """
        A file opened with C{openFile} is closed when the connection is lost.
        """
        d = self.client.openFile(
            b"testfile1", filetransfer.FXF_READ | filetransfer.FXF_WRITE, {}
        )
        self._emptyBuffers()

        oldClose = os.close
        closed = []

        def close(fd):
            closed.append(fd)
            oldClose(fd)

        self.patch(os, "close", close)

        def _fileOpened(openFile):
            fd = self.server.openFiles[openFile.handle[4:]].fd
            self.serverTransport.loseConnection()
            self.clientTransport.loseConnection()
            self.serverTransport.clearBuffer()
            self.clientTransport.clearBuffer()
            self.assertEqual(self.server.openFiles, {})
            self.assertIn(fd, closed)

        d.addCallback(_fileOpened)
        return d

    def test_openedDirectoryClosedWithConnection(self):
        """
        A directory opened with C{openDirectory} is close when the connection
        is lost.
        """
        d = self.client.openDirectory("")
        self._emptyBuffers()

        def _getFiles(openDir):
            self.serverTransport.loseConnection()
            self.clientTransport.loseConnection()
            self.serverTransport.clearBuffer()
            self.clientTransport.clearBuffer()
            self.assertEqual(self.server.openDirs, {})

        d.addCallback(_getFiles)
        return d

    def test_openFileIO(self):
        d = self.client.openFile(
            b"testfile1", filetransfer.FXF_READ | filetransfer.FXF_WRITE, {}
        )
        self._emptyBuffers()

        def _fileOpened(openFile):
            self.assertEqual(openFile, filetransfer.ISFTPFile(openFile))
            d = _readChunk(openFile)
            d.addCallback(_writeChunk, openFile)
            return d

        def _readChunk(openFile):
            d = openFile.readChunk(0, 20)
            self._emptyBuffers()
            d.addCallback(self.assertEqual, b"a" * 10 + b"b" * 10)
            return d

        def _writeChunk(_, openFile):
            d = openFile.writeChunk(20, b"c" * 10)
            self._emptyBuffers()
            d.addCallback(_readChunk2, openFile)
            return d

        def _readChunk2(_, openFile):
            d = openFile.readChunk(0, 30)
            self._emptyBuffers()
            d.addCallback(self.assertEqual, b"a" * 10 + b"b" * 10 + b"c" * 10)
            return d

        d.addCallback(_fileOpened)
        return d

    def test_closedFileGetAttrs(self):
        d = self.client.openFile(
            b"testfile1", filetransfer.FXF_READ | filetransfer.FXF_WRITE, {}
        )
        self._emptyBuffers()

        def _getAttrs(_, openFile):
            d = openFile.getAttrs()
            self._emptyBuffers()
            return d

        def _err(f):
            self.flushLoggedErrors()
            return f

        def _close(openFile):
            d = openFile.close()
            self._emptyBuffers()
            d.addCallback(_getAttrs, openFile)
            d.addErrback(_err)
            return self.assertFailure(d, filetransfer.SFTPError)

        d.addCallback(_close)
        return d

    def test_openFileAttributes(self):
        d = self.client.openFile(
            b"testfile1", filetransfer.FXF_READ | filetransfer.FXF_WRITE, {}
        )
        self._emptyBuffers()

        def _getAttrs(openFile):
            d = openFile.getAttrs()
            self._emptyBuffers()
            d.addCallback(_getAttrs2)
            return d

        def _getAttrs2(attrs1):
            d = self.client.getAttrs(b"testfile1")
            self._emptyBuffers()
            d.addCallback(self.assertEqual, attrs1)
            return d

        return d.addCallback(_getAttrs)

    def test_openFileSetAttrs(self):
        # XXX test setAttrs
        # Ok, how about this for a start?  It caught a bug :)  -- spiv.
        d = self.client.openFile(
            b"testfile1", filetransfer.FXF_READ | filetransfer.FXF_WRITE, {}
        )
        self._emptyBuffers()

        def _getAttrs(openFile):
            d = openFile.getAttrs()
            self._emptyBuffers()
            d.addCallback(_setAttrs)
            return d

        def _setAttrs(attrs):
            attrs["atime"] = 0
            d = self.client.setAttrs(b"testfile1", attrs)
            self._emptyBuffers()
            d.addCallback(_getAttrs2)
            d.addCallback(self.assertEqual, attrs)
            return d

        def _getAttrs2(_):
            d = self.client.getAttrs(b"testfile1")
            self._emptyBuffers()
            return d

        d.addCallback(_getAttrs)
        return d

    def test_openFileExtendedAttributes(self):
        """
        Check that L{filetransfer.FileTransferClient.openFile} can send
        extended attributes, that should be extracted server side. By default,
        they are ignored, so we just verify they are correctly parsed.
        """
        savedAttributes = {}
        oldOpenFile = self.server.client.openFile

        def openFile(filename, flags, attrs):
            savedAttributes.update(attrs)
            return oldOpenFile(filename, flags, attrs)

        self.server.client.openFile = openFile

        d = self.client.openFile(
            b"testfile1",
            filetransfer.FXF_READ | filetransfer.FXF_WRITE,
            {"ext_foo": b"bar"},
        )
        self._emptyBuffers()

        def check(ign):
            self.assertEqual(savedAttributes, {"ext_foo": b"bar"})

        return d.addCallback(check)

    def test_removeFile(self):
        d = self.client.getAttrs(b"testRemoveFile")
        self._emptyBuffers()

        def _removeFile(ignored):
            d = self.client.removeFile(b"testRemoveFile")
            self._emptyBuffers()
            return d

        d.addCallback(_removeFile)
        d.addCallback(_removeFile)
        return self.assertFailure(d, filetransfer.SFTPError)

    def test_renameFile(self):
        d = self.client.getAttrs(b"testRenameFile")
        self._emptyBuffers()

        def _rename(attrs):
            d = self.client.renameFile(b"testRenameFile", b"testRenamedFile")
            self._emptyBuffers()
            d.addCallback(_testRenamed, attrs)
            return d

        def _testRenamed(_, attrs):
            d = self.client.getAttrs(b"testRenamedFile")
            self._emptyBuffers()
            d.addCallback(self.assertEqual, attrs)

        return d.addCallback(_rename)

    def test_directoryBad(self):
        d = self.client.getAttrs(b"testMakeDirectory")
        self._emptyBuffers()
        return self.assertFailure(d, filetransfer.SFTPError)

    def test_directoryCreation(self):
        d = self.client.makeDirectory(b"testMakeDirectory", {})
        self._emptyBuffers()

        def _getAttrs(_):
            d = self.client.getAttrs(b"testMakeDirectory")
            self._emptyBuffers()
            return d

        # XXX not until version 4/5
        # self.assertEqual(filetransfer.FILEXFER_TYPE_DIRECTORY&attrs['type'],
        #                     filetransfer.FILEXFER_TYPE_DIRECTORY)

        def _removeDirectory(_):
            d = self.client.removeDirectory(b"testMakeDirectory")
            self._emptyBuffers()
            return d

        d.addCallback(_getAttrs)
        d.addCallback(_removeDirectory)
        d.addCallback(_getAttrs)
        return self.assertFailure(d, filetransfer.SFTPError)

    def test_openDirectory(self):
        d = self.client.openDirectory(b"")
        self._emptyBuffers()
        files = []

        def _getFiles(openDir):
            def append(f):
                files.append(f)
                return openDir

            d = defer.maybeDeferred(openDir.next)
            self._emptyBuffers()
            d.addCallback(append)
            d.addCallback(_getFiles)
            d.addErrback(_close, openDir)
            return d

        def _checkFiles(ignored):
            fs = list(list(zip(*files))[0])
            fs.sort()
            self.assertEqual(
                fs,
                [
                    b".testHiddenFile",
                    b"testDirectory",
                    b"testRemoveFile",
                    b"testRenameFile",
                    b"testfile1",
                ],
            )

        def _close(_, openDir):
            d = openDir.close()
            self._emptyBuffers()
            return d

        d.addCallback(_getFiles)
        d.addCallback(_checkFiles)
        return d

    def test_linkDoesntExist(self):
        d = self.client.getAttrs(b"testLink")
        self._emptyBuffers()
        return self.assertFailure(d, filetransfer.SFTPError)

    def test_linkSharesAttrs(self):
        d = self.client.makeLink(b"testLink", b"testfile1")
        self._emptyBuffers()

        def _getFirstAttrs(_):
            d = self.client.getAttrs(b"testLink", 1)
            self._emptyBuffers()
            return d

        def _getSecondAttrs(firstAttrs):
            d = self.client.getAttrs(b"testfile1")
            self._emptyBuffers()
            d.addCallback(self.assertEqual, firstAttrs)
            return d

        d.addCallback(_getFirstAttrs)
        return d.addCallback(_getSecondAttrs)

    def test_linkPath(self):
        d = self.client.makeLink(b"testLink", b"testfile1")
        self._emptyBuffers()

        def _readLink(_):
            d = self.client.readLink(b"testLink")
            self._emptyBuffers()
            testFile = FilePath(os.getcwd()).preauthChild(self.testDir.path)
            testFile = testFile.child("testfile1")
            d.addCallback(self.assertEqual, testFile.path)
            return d

        def _realPath(_):
            d = self.client.realPath(b"testLink")
            self._emptyBuffers()
            testLink = FilePath(os.getcwd()).preauthChild(self.testDir.path)
            testLink = testLink.child("testfile1")
            d.addCallback(self.assertEqual, testLink.path)
            return d

        d.addCallback(_readLink)
        d.addCallback(_realPath)
        return d

    def test_extendedRequest(self):
        d = self.client.extendedRequest(b"testExtendedRequest", b"foo")
        self._emptyBuffers()
        d.addCallback(self.assertEqual, b"bar")
        d.addCallback(self._cbTestExtendedRequest)
        return d

    def _cbTestExtendedRequest(self, ignored):
        d = self.client.extendedRequest(b"testBadRequest", b"")
        self._emptyBuffers()
        return self.assertFailure(d, NotImplementedError)

    @defer.inlineCallbacks
    @skipIf(_PY37PLUS, "Broken by PEP 479 and deprecated.")
    def test_openDirectoryIterator(self):
        """
        Check that the object returned by
        L{filetransfer.FileTransferClient.openDirectory} can be used
        as an iterator.
        """

        # This function is a little more complicated than it would be
        # normally, since we need to call _emptyBuffers() after
        # creating any SSH-related Deferreds, but before waiting on
        # them via yield.

        d = self.client.openDirectory(b"")
        self._emptyBuffers()
        openDir = yield d

        filenames = set()
        try:
            for f in openDir:
                self._emptyBuffers()
                (filename, _, fileattrs) = yield f
                filenames.add(filename)
        finally:
            d = openDir.close()
            self._emptyBuffers()
            yield d

        self._emptyBuffers()

        self.assertEqual(
            filenames,
            {
                b".testHiddenFile",
                b"testDirectory",
                b"testRemoveFile",
                b"testRenameFile",
                b"testfile1",
            },
        )

    @defer.inlineCallbacks
    def test_openDirectoryIteratorDeprecated(self):
        """
        Using client.openDirectory as an iterator is deprecated.
        """
        d = self.client.openDirectory(b"")
        self._emptyBuffers()
        openDir = yield d
        oneFile = openDir.next()
        self._emptyBuffers()
        yield oneFile

        warnings = self.flushWarnings()
        message = (
            "Using twisted.conch.ssh.filetransfer.ClientDirectory"
            " as an iterator was deprecated in Twisted 18.9.0."
        )
        self.assertEqual(1, len(warnings))
        self.assertEqual(DeprecationWarning, warnings[0]["category"])
        self.assertEqual(message, warnings[0]["message"])

    @defer.inlineCallbacks
    def test_closedConnectionCancelsRequests(self):
        """
        If there are requests outstanding when the connection
        is closed for any reason, they should fail.
        """

        d = self.client.openFile(b"testfile1", filetransfer.FXF_READ, {})
        self._emptyBuffers()
        fh = yield d

        # Intercept the handling of the read request on the server side
        gotReadRequest = []

        def _slowRead(offset, length):
            self.assertEqual(gotReadRequest, [])
            d = defer.Deferred()
            gotReadRequest.append(offset)
            return d

        [serverSideFh] = self.server.openFiles.values()
        serverSideFh.readChunk = _slowRead
        del serverSideFh

        # Make a read request, dropping the connection before the reply
        # is sent
        d = fh.readChunk(100, 200)
        self._emptyBuffers()
        self.assertEqual(len(gotReadRequest), 1)
        self.assertNoResult(d)

        # Lost connection should cause an errback
        self.serverTransport.loseConnection()
        self.serverTransport.clearBuffer()
        self.clientTransport.clearBuffer()
        self._emptyBuffers()

        self.assertFalse(self.client.connected)
        self.failureResultOf(d, ConnectionLost)

        # Further attempts to use the filetransfer session should fail
        # immediately
        d = fh.getAttrs()
        self.failureResultOf(d, ConnectionLost)


class FakeConn:
    def sendClose(self, channel):
        pass


@skipIf(not unix, "can't run on non-posix computers")
class FileTransferCloseTests(TestCase):
    def setUp(self):
        self.avatar = TestAvatar()

    def buildServerConnection(self):
        # make a server connection
        conn = connection.SSHConnection()
        # server connections have a 'self.transport.avatar'.

        class DummyTransport:
            def __init__(self):
                self.transport = self

            def sendPacket(self, kind, data):
                pass

            def logPrefix(self):
                return "dummy transport"

        conn.transport = DummyTransport()
        conn.transport.avatar = self.avatar
        return conn

    def interceptConnectionLost(self, sftpServer):
        self.connectionLostFired = False
        origConnectionLost = sftpServer.connectionLost

        def connectionLost(reason):
            self.connectionLostFired = True
            origConnectionLost(reason)

        sftpServer.connectionLost = connectionLost

    def assertSFTPConnectionLost(self):
        self.assertTrue(
            self.connectionLostFired, "sftpServer's connectionLost was not called"
        )

    def test_sessionClose(self):
        """
        Closing a session should notify an SFTP subsystem launched by that
        session.
        """
        # make a session
        testSession = session.SSHSession(conn=FakeConn(), avatar=self.avatar)

        # start an SFTP subsystem on the session
        testSession.request_subsystem(common.NS(b"sftp"))
        sftpServer = testSession.client.transport.proto

        # intercept connectionLost so we can check that it's called
        self.interceptConnectionLost(sftpServer)

        # close session
        testSession.closeReceived()

        self.assertSFTPConnectionLost()

    def test_clientClosesChannelOnConnnection(self):
        """
        A client sending CHANNEL_CLOSE should trigger closeReceived on the
        associated channel instance.
        """
        conn = self.buildServerConnection()

        # somehow get a session
        packet = common.NS(b"session") + struct.pack(">L", 0) * 3
        conn.ssh_CHANNEL_OPEN(packet)
        sessionChannel = conn.channels[0]

        sessionChannel.request_subsystem(common.NS(b"sftp"))
        sftpServer = sessionChannel.client.transport.proto
        self.interceptConnectionLost(sftpServer)

        # intercept closeReceived
        self.interceptConnectionLost(sftpServer)

        # close the connection
        conn.ssh_CHANNEL_CLOSE(struct.pack(">L", 0))

        self.assertSFTPConnectionLost()

    def test_stopConnectionServiceClosesChannel(self):
        """
        Closing an SSH connection should close all sessions within it.
        """
        conn = self.buildServerConnection()

        # somehow get a session
        packet = common.NS(b"session") + struct.pack(">L", 0) * 3
        conn.ssh_CHANNEL_OPEN(packet)
        sessionChannel = conn.channels[0]

        sessionChannel.request_subsystem(common.NS(b"sftp"))
        sftpServer = sessionChannel.client.transport.proto
        self.interceptConnectionLost(sftpServer)

        # close the connection
        conn.serviceStopped()

        self.assertSFTPConnectionLost()


@skipIf(not cryptography, "Cannot run without cryptography")
class ConstantsTests(TestCase):
    """
    Tests for the constants used by the SFTP protocol implementation.

    @ivar filexferSpecExcerpts: Excerpts from the
        draft-ietf-secsh-filexfer-02.txt (draft) specification of the SFTP
        protocol.  There are more recent drafts of the specification, but this
        one describes version 3, which is what conch (and OpenSSH) implements.
    """

    filexferSpecExcerpts = [
        """
           The following values are defined for packet types.

                #define SSH_FXP_INIT                1
                #define SSH_FXP_VERSION             2
                #define SSH_FXP_OPEN                3
                #define SSH_FXP_CLOSE               4
                #define SSH_FXP_READ                5
                #define SSH_FXP_WRITE               6
                #define SSH_FXP_LSTAT               7
                #define SSH_FXP_FSTAT               8
                #define SSH_FXP_SETSTAT             9
                #define SSH_FXP_FSETSTAT           10
                #define SSH_FXP_OPENDIR            11
                #define SSH_FXP_READDIR            12
                #define SSH_FXP_REMOVE             13
                #define SSH_FXP_MKDIR              14
                #define SSH_FXP_RMDIR              15
                #define SSH_FXP_REALPATH           16
                #define SSH_FXP_STAT               17
                #define SSH_FXP_RENAME             18
                #define SSH_FXP_READLINK           19
                #define SSH_FXP_SYMLINK            20
                #define SSH_FXP_STATUS            101
                #define SSH_FXP_HANDLE            102
                #define SSH_FXP_DATA              103
                #define SSH_FXP_NAME              104
                #define SSH_FXP_ATTRS             105
                #define SSH_FXP_EXTENDED          200
                #define SSH_FXP_EXTENDED_REPLY    201

           Additional packet types should only be defined if the protocol
           version number (see Section ``Protocol Initialization'') is
           incremented, and their use MUST be negotiated using the version
           number.  However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY
           packets can be used to implement vendor-specific extensions.  See
           Section ``Vendor-Specific-Extensions'' for more details.
        """,
        """
            The flags bits are defined to have the following values:

                #define SSH_FILEXFER_ATTR_SIZE          0x00000001
                #define SSH_FILEXFER_ATTR_UIDGID        0x00000002
                #define SSH_FILEXFER_ATTR_PERMISSIONS   0x00000004
                #define SSH_FILEXFER_ATTR_ACMODTIME     0x00000008
                #define SSH_FILEXFER_ATTR_EXTENDED      0x80000000

        """,
        """
            The `pflags' field is a bitmask.  The following bits have been
           defined.

                #define SSH_FXF_READ            0x00000001
                #define SSH_FXF_WRITE           0x00000002
                #define SSH_FXF_APPEND          0x00000004
                #define SSH_FXF_CREAT           0x00000008
                #define SSH_FXF_TRUNC           0x00000010
                #define SSH_FXF_EXCL            0x00000020
        """,
        """
            Currently, the following values are defined (other values may be
           defined by future versions of this protocol):

                #define SSH_FX_OK                            0
                #define SSH_FX_EOF                           1
                #define SSH_FX_NO_SUCH_FILE                  2
                #define SSH_FX_PERMISSION_DENIED             3
                #define SSH_FX_FAILURE                       4
                #define SSH_FX_BAD_MESSAGE                   5
                #define SSH_FX_NO_CONNECTION                 6
                #define SSH_FX_CONNECTION_LOST               7
                #define SSH_FX_OP_UNSUPPORTED                8
        """,
    ]

    def test_constantsAgainstSpec(self):
        """
        The constants used by the SFTP protocol implementation match those
        found by searching through the spec.
        """
        constants = {}
        for excerpt in self.filexferSpecExcerpts:
            for line in excerpt.splitlines():
                m = re.match(r"^\s*#define SSH_([A-Z_]+)\s+([0-9x]*)\s*$", line)
                if m:
                    constants[m.group(1)] = int(m.group(2), 0)
        self.assertTrue(
            len(constants) > 0, "No constants found (the test must be buggy)."
        )
        for k, v in constants.items():
            self.assertEqual(v, getattr(filetransfer, k))


@skipIf(not cryptography, "Cannot run without cryptography")
class RawPacketDataTests(TestCase):
    """
    Tests for L{filetransfer.FileTransferClient} which explicitly craft certain
    less common protocol messages to exercise their handling.
    """

    def setUp(self):
        self.ftc = filetransfer.FileTransferClient()

    def test_packetSTATUS(self):
        """
        A STATUS packet containing a result code, a message, and a language is
        parsed to produce the result of an outstanding request L{Deferred}.

        @see: U{section 9.1<http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-9.1>}
            of the SFTP Internet-Draft.
        """
        d = defer.Deferred()
        d.addCallback(self._cbTestPacketSTATUS)
        self.ftc.openRequests[1] = d
        data = (
            struct.pack("!LL", 1, filetransfer.FX_OK)
            + common.NS(b"msg")
            + common.NS(b"lang")
        )
        self.ftc.packet_STATUS(data)
        return d

    def _cbTestPacketSTATUS(self, result):
        """
        Assert that the result is a two-tuple containing the message and
        language from the STATUS packet.
        """
        self.assertEqual(result[0], b"msg")
        self.assertEqual(result[1], b"lang")

    def test_packetSTATUSShort(self):
        """
        A STATUS packet containing only a result code can also be parsed to
        produce the result of an outstanding request L{Deferred}.  Such packets
        are sent by some SFTP implementations, though not strictly legal.

        @see: U{section 9.1<http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-9.1>}
            of the SFTP Internet-Draft.
        """
        d = defer.Deferred()
        d.addCallback(self._cbTestPacketSTATUSShort)
        self.ftc.openRequests[1] = d
        data = struct.pack("!LL", 1, filetransfer.FX_OK)
        self.ftc.packet_STATUS(data)
        return d

    def _cbTestPacketSTATUSShort(self, result):
        """
        Assert that the result is a two-tuple containing empty strings, since
        the STATUS packet had neither a message nor a language.
        """
        self.assertEqual(result[0], b"")
        self.assertEqual(result[1], b"")

    def test_packetSTATUSWithoutLang(self):
        """
        A STATUS packet containing a result code and a message but no language
        can also be parsed to produce the result of an outstanding request
        L{Deferred}.  Such packets are sent by some SFTP implementations, though
        not strictly legal.

        @see: U{section 9.1<http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-9.1>}
            of the SFTP Internet-Draft.
        """
        d = defer.Deferred()
        d.addCallback(self._cbTestPacketSTATUSWithoutLang)
        self.ftc.openRequests[1] = d
        data = struct.pack("!LL", 1, filetransfer.FX_OK) + common.NS(b"msg")
        self.ftc.packet_STATUS(data)
        return d

    def _cbTestPacketSTATUSWithoutLang(self, result):
        """
        Assert that the result is a two-tuple containing the message from the
        STATUS packet and an empty string, since the language was missing.
        """
        self.assertEqual(result[0], b"msg")
        self.assertEqual(result[1], b"")
