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809a4eb249
I just ran into a bug in which the testcrypt child process was cleanly terminated, but at least one Python object was left lying around containing the identifier of a testcrypt object that had never been freed. On program exit, the Python reference count on that object went to zero, the __del__ method was invoked, and childprocess.funcall started a _new_ instance of testcrypt just so it could tell it to free the object identifier - which, of course, the new testcrypt had never heard of! We can already tell the difference between a ChildProcess object which has no subprocess because it hasn't yet been started, and one which has no subprocess because it's terminated: the latter has exitstatus set to something other than None. So now we enforce by assertion that we don't ever restart the child process, and the __del__ method avoids doing anything if the child has already finished.
314 lines
12 KiB
Python
314 lines
12 KiB
Python
import sys
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import os
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import numbers
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import subprocess
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import re
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import struct
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from binascii import hexlify
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# Expect to be run from the 'test' subdirectory, one level down from
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# the main source
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putty_srcdir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
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def unicode_to_bytes(arg):
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# Slightly fiddly way to do this which should work in Python 2 and 3
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if isinstance(arg, type(u'a')) and not isinstance(arg, type(b'a')):
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arg = arg.encode("UTF-8")
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return arg
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def bytevals(b):
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return struct.unpack("{:d}B".format(len(b)), b)
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def valbytes(b):
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b = list(b)
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return struct.pack("{:d}B".format(len(b)), *b)
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class ChildProcessFailure(Exception):
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pass
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class ChildProcess(object):
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def __init__(self):
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self.sp = None
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self.debug = None
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self.exitstatus = None
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self.exception = None
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dbg = os.environ.get("PUTTY_TESTCRYPT_DEBUG")
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if dbg is not None:
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if dbg == "stderr":
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self.debug = sys.stderr
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else:
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sys.stderr.write("Unknown value '{}' for PUTTY_TESTCRYPT_DEBUG"
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" (try 'stderr'\n")
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def start(self):
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assert self.sp is None
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override_command = os.environ.get("PUTTY_TESTCRYPT")
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if override_command is None:
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cmd = [os.path.join(putty_srcdir, "testcrypt")]
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shell = False
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else:
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cmd = override_command
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shell = True
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self.sp = subprocess.Popen(
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cmd, shell=shell, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
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def write_line(self, line):
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if self.exception is not None:
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# Re-raise our fatal-error exception, if it previously
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# occurred in a context where it couldn't be propagated (a
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# __del__ method).
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raise self.exception
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if self.debug is not None:
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self.debug.write("send: {}\n".format(line))
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self.sp.stdin.write(line + b"\n")
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self.sp.stdin.flush()
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def read_line(self):
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line = self.sp.stdout.readline()
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if len(line) == 0:
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self.exception = ChildProcessFailure("received EOF from testcrypt")
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raise self.exception
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line = line.rstrip(b"\r\n")
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if self.debug is not None:
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self.debug.write("recv: {}\n".format(line))
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return line
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def already_terminated(self):
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return self.sp is None and self.exitstatus is not None
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def funcall(self, cmd, args):
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if self.sp is None:
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assert self.exitstatus is None
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self.start()
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self.write_line(unicode_to_bytes(cmd) + b" " + b" ".join(
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unicode_to_bytes(arg) for arg in args))
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argcount = int(self.read_line())
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return [self.read_line() for arg in range(argcount)]
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def wait_for_exit(self):
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if self.sp is not None:
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self.sp.stdin.close()
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self.exitstatus = self.sp.wait()
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self.sp = None
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def check_return_status(self):
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self.wait_for_exit()
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if self.exitstatus is not None and self.exitstatus != 0:
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raise ChildProcessFailure("testcrypt returned exit status {}"
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.format(self.exitstatus))
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childprocess = ChildProcess()
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method_prefixes = {
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'val_wpoint': 'ecc_weierstrass_',
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'val_mpoint': 'ecc_montgomery_',
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'val_epoint': 'ecc_edwards_',
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'val_hash': 'ssh_hash_',
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'val_mac': 'ssh_mac_',
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'val_key': 'ssh_key_',
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'val_cipher': 'ssh_cipher_',
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'val_dh': 'dh_',
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'val_ecdh': 'ssh_ecdhkex_',
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'val_rsakex': 'ssh_rsakex_',
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'val_prng': 'prng_',
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'val_pcs': 'pcs_',
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}
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method_lists = {t: [] for t in method_prefixes}
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class Value(object):
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def __init__(self, typename, ident):
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self._typename = typename
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self._ident = ident
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for methodname, function in method_lists.get(self._typename, []):
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setattr(self, methodname,
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(lambda f: lambda *args: f(self, *args))(function))
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def _consumed(self):
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self._ident = None
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def __repr__(self):
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return "Value({!r}, {!r})".format(self._typename, self._ident)
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def __del__(self):
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if self._ident is not None and not childprocess.already_terminated():
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try:
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childprocess.funcall("free", [self._ident])
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except ChildProcessFailure:
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# If we see this exception now, we can't do anything
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# about it, because exceptions don't propagate out of
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# __del__ methods. Squelch it to prevent the annoying
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# runtime warning from Python, and the
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# 'self.exception' mechanism in the ChildProcess class
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# will raise it again at the next opportunity.
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#
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# (This covers both the case where testcrypt crashes
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# _during_ one of these free operations, and the
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# silencing of cascade failures when we try to send a
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# "free" command to testcrypt after it had already
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# crashed for some other reason.)
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pass
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def __long__(self):
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if self._typename != "val_mpint":
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raise TypeError("testcrypt values of types other than mpint"
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" cannot be converted to integer")
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hexval = childprocess.funcall("mp_dump", [self._ident])[0]
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return 0 if len(hexval) == 0 else int(hexval, 16)
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def __int__(self):
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return int(self.__long__())
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def make_argword(arg, argtype, fnname, argindex, to_preserve):
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typename, consumed = argtype
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if typename.startswith("opt_"):
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if arg is None:
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return "NULL"
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typename = typename[4:]
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if typename == "val_string":
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arg = unicode_to_bytes(arg)
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if isinstance(arg, bytes):
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retwords = childprocess.funcall(
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"newstring", ["".join("%{:02x}".format(b)
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for b in bytevals(arg))])
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arg = make_retvals([typename], retwords, unpack_strings=False)[0]
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to_preserve.append(arg)
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if typename == "val_mpint" and isinstance(arg, numbers.Integral):
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retwords = childprocess.funcall("mp_literal", ["0x{:x}".format(arg)])
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arg = make_retvals([typename], retwords)[0]
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to_preserve.append(arg)
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if isinstance(arg, Value):
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if arg._typename != typename:
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raise TypeError(
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"{}() argument {:d} should be {} ({} given)".format(
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fnname, argindex, typename, arg._typename))
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ident = arg._ident
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if consumed:
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arg._consumed()
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return ident
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if typename == "uint" and isinstance(arg, numbers.Integral):
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return "0x{:x}".format(arg)
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if typename in {
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"hashalg", "macalg", "keyalg", "cipheralg",
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"dh_group", "ecdh_alg", "rsaorder"}:
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arg = unicode_to_bytes(arg)
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if isinstance(arg, bytes) and b" " not in arg:
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return arg
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raise TypeError(
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"Can't convert {}() argument {:d} to {} (value was {!r})".format(
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fnname, argindex, typename, arg))
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def unpack_string(identifier):
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retwords = childprocess.funcall("getstring", [identifier])
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childprocess.funcall("free", [identifier])
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return re.sub(b"%[0-9A-F][0-9A-F]",
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lambda m: valbytes([int(m.group(0)[1:], 16)]),
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retwords[0])
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def unpack_mp(identifier):
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retwords = childprocess.funcall("mp_dump", [identifier])
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childprocess.funcall("free", [identifier])
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return int(retwords[0], 16)
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def make_retval(rettype, word, unpack_strings):
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if rettype.startswith("opt_"):
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if word == b"NULL":
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return None
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rettype = rettype[4:]
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if rettype == "val_string" and unpack_strings:
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return unpack_string(word)
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if rettype == "val_keycomponents":
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kc = {}
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retwords = childprocess.funcall("key_components_count", [word])
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for i in range(int(retwords[0], 0)):
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args = [word, "{:d}".format(i)]
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retwords = childprocess.funcall("key_components_nth_name", args)
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kc_key = unpack_string(retwords[0])
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retwords = childprocess.funcall("key_components_nth_str", args)
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if retwords[0] != b"NULL":
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kc_value = unpack_string(retwords[0]).decode("ASCII")
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else:
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retwords = childprocess.funcall("key_components_nth_mp", args)
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kc_value = unpack_mp(retwords[0])
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kc[kc_key.decode("ASCII")] = kc_value
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childprocess.funcall("free", [word])
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return kc
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if rettype.startswith("val_"):
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return Value(rettype, word)
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elif rettype == "int" or rettype == "uint":
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return int(word, 0)
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elif rettype == "boolean":
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assert word == b"true" or word == b"false"
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return word == b"true"
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raise TypeError("Can't deal with return value {!r} of type {!r}"
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.format(word, rettype))
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def make_retvals(rettypes, retwords, unpack_strings=True):
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assert len(rettypes) == len(retwords) # FIXME: better exception
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return [make_retval(rettype, word, unpack_strings)
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for rettype, word in zip(rettypes, retwords)]
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class Function(object):
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def __init__(self, fnname, rettypes, argtypes):
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self.fnname = fnname
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self.rettypes = rettypes
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self.argtypes = argtypes
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def __repr__(self):
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return "<Function {}>".format(self.fnname)
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def __call__(self, *args):
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if len(args) != len(self.argtypes):
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raise TypeError(
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"{}() takes exactly {} arguments ({} given)".format(
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self.fnname, len(self.argtypes), len(args)))
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to_preserve = []
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retwords = childprocess.funcall(
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self.fnname, [make_argword(args[i], self.argtypes[i],
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self.fnname, i, to_preserve)
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for i in range(len(args))])
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retvals = make_retvals(self.rettypes, retwords)
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if len(retvals) == 0:
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return None
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if len(retvals) == 1:
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return retvals[0]
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return tuple(retvals)
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def _setup(scope):
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header_file = os.path.join(putty_srcdir, "testcrypt.h")
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linere = re.compile(r'^FUNC\d+\((.*)\)$')
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valprefix = "val_"
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outprefix = "out_"
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optprefix = "opt_"
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consprefix = "consumed_"
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def trim_argtype(arg):
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if arg.startswith(optprefix):
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return optprefix + trim_argtype(arg[len(optprefix):])
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if (arg.startswith(valprefix) and
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"_" in arg[len(valprefix):]):
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# Strip suffixes like val_string_asciz
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arg = arg[:arg.index("_", len(valprefix))]
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return arg
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with open(header_file) as f:
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for line in iter(f.readline, ""):
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line = line.rstrip("\r\n").replace(" ", "")
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m = linere.match(line)
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if m is not None:
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words = m.group(1).split(",")
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function = words[1]
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rettypes = []
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argtypes = []
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argsconsumed = []
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if words[0] != "void":
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rettypes.append(trim_argtype(words[0]))
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for arg in words[2:]:
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if arg.startswith(outprefix):
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rettypes.append(trim_argtype(arg[len(outprefix):]))
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else:
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consumed = False
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if arg.startswith(consprefix):
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arg = arg[len(consprefix):]
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consumed = True
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arg = trim_argtype(arg)
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argtypes.append((arg, consumed))
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func = Function(function, rettypes, argtypes)
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scope[function] = func
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if len(argtypes) > 0:
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t = argtypes[0][0]
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if (t in method_prefixes and
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function.startswith(method_prefixes[t])):
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methodname = function[len(method_prefixes[t]):]
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method_lists[t].append((methodname, func))
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_setup(globals())
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del _setup
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