mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-03-21 22:28:37 -05:00
3743859f97
Yesterday's commit 52ee636b092c199 which further extended the huge pile of arity-specific annoying wrapper macros pushed me over the edge and inspired me to give some harder thought to finding a way to handle all arities at once. And this time I found one! The new technique changes the syntax of the function specifications in testcrypt.h. In particular, they now have to specify a _name_ for each parameter as well as a type, because the macros generating the C marshalling wrappers will need a structure field for each parameter and cpp isn't flexible enough to generate names for those fields automatically. Rather than tediously name them arg1, arg2 etc, I've reused the names of the parameters from the prototypes or definitions of the underlying real functions (via a one-off auto-extraction process starting from the output of 'clang -Xclang -dump-ast' plus some manual polishing), which means testcrypt.h is now a bit more self-documenting. The testcrypt.py end of the mechanism is rewritten to eat the new format. Since it's got more complicated syntax and nested parens and things, I've written something a bit like a separated lexer/parser system in place of the previous crude regex matcher, which should enforce that the whole header file really does conform to the restricted syntax it has to fit into. The new system uses a lot less code in testcrypt.c, but I've made up for that by also writing a long comment explaining how it works, which was another thing the previous system lacked! Similarly, the new testcrypt.h has some long-overdue instructions at the top.
408 lines
15 KiB
Python
408 lines
15 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 string
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import struct
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from binascii import hexlify
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assert sys.version_info[:2] >= (3,0), "This is Python 3 code"
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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 coerce_to_bytes(arg):
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return arg.encode("UTF-8") if isinstance(arg, str) else arg
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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(coerce_to_bytes(cmd) + b" " + b" ".join(
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coerce_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': 'ssh2_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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'val_pockle': 'pockle_',
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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 marshal_string(val):
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val = coerce_to_bytes(val)
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assert isinstance(val, bytes), "Bad type for val_string input"
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return "".join(
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chr(b) if (0x20 <= b < 0x7F and b != 0x25)
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else "%{:02x}".format(b)
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for b in val)
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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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retwords = childprocess.funcall("newstring", [marshal_string(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 == "boolean":
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return "true" if arg else "false"
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if typename in {
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"hashalg", "macalg", "keyalg", "cipheralg",
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"dh_group", "ecdh_alg", "rsaorder", "primegenpolicy",
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"argon2flavour", "fptype", "httpdigesthash"}:
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arg = coerce_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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if typename == "mpint_list":
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sublist = [make_argword(len(arg), ("uint", False),
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fnname, argindex, to_preserve)]
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for val in arg:
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sublist.append(make_argword(val, ("val_mpint", False),
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fnname, argindex, to_preserve))
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return b" ".join(coerce_to_bytes(sub) for sub in sublist)
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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: bytes([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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elif rettype in {"pocklestatus", "mr_result"}:
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return word.decode("ASCII")
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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 _lex_testcrypt_header(header):
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pat = re.compile(
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# Skip any combination of whitespace and comments
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'(?:{})*'.format('|'.join((
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'[ \t\n]', # whitespace
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'/\\*(?:.|\n)*?\\*/', # C90-style /* ... */ comment, ended eagerly
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'//[^\n]*\n', # C99-style comment to end-of-line
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))) +
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# And then match a token
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'({})'.format('|'.join((
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# Punctuation
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'\(',
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'\)',
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',',
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# Identifier
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'[A-Za-z_][A-Za-z0-9_]*',
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# End of string
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'$',
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)))
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)
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pos = 0
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end = len(header)
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while pos < end:
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m = pat.match(header, pos)
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assert m is not None, (
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"Failed to lex testcrypt.h at byte position {:d}".format(pos))
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pos = m.end()
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tok = m.group(1)
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if len(tok) == 0:
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assert pos == end, (
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"Empty token should only be returned at end of string")
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yield tok, m.start(1)
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def _parse_testcrypt_header(tokens):
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def is_id(tok):
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return tok[0] in string.ascii_letters+"_"
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def expect(what, why, eof_ok=False):
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tok, pos = next(tokens)
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if tok == '' and eof_ok:
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return None
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if hasattr(what, '__call__'):
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description = lambda: ""
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ok = what(tok)
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elif isinstance(what, set):
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description = lambda: " or ".join("'"+x+"' " for x in sorted(what))
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ok = tok in what
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else:
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description = lambda: "'"+what+"' "
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ok = tok == what
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if not ok:
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sys.exit("testcrypt.h:{:d}: expected {}{}".format(
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pos, description(), why))
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return tok
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while True:
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tok = expect("FUNC", "at start of function specification", eof_ok=True)
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if tok is None:
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break
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expect("(", "after FUNC")
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rettype = expect(is_id, "return type")
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expect(",", "after return type")
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funcname = expect(is_id, "function name")
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expect(",", "after function name")
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expect("(", "to begin argument list")
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args = []
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firstargkind = expect({"ARG", "VOID"}, "at start of argument list")
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if firstargkind == "VOID":
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expect(")", "after VOID")
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else:
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while True:
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# Every time we come back to the top of this loop, we've
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# just seen 'ARG'
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expect("(", "after ARG")
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argtype = expect(is_id, "argument type")
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expect(",", "after argument type")
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argname = expect(is_id, "argument name")
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args.append((argtype, argname))
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expect(")", "at end of ARG")
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punct = expect({",", ")"}, "after argument")
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if punct == ")":
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break
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expect("ARG", "to begin next argument")
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expect(")", "at end of FUNC")
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yield funcname, rettype, args
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def _setup(scope):
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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(os.path.join(putty_srcdir, "testcrypt.h")) as f:
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header = f.read()
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tokens = _lex_testcrypt_header(header)
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for function, rettype, arglist in _parse_testcrypt_header(tokens):
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rettypes = []
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if rettype != "void":
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rettypes.append(trim_argtype(rettype))
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argtypes = []
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argsconsumed = []
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for arg, argname in arglist:
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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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