from __future__ import absolute_import, print_function, division import os.path import re import codecs import unicodedata import importlib import inspect import six def always_bytes(unicode_or_bytes, *encode_args): if isinstance(unicode_or_bytes, six.text_type): return unicode_or_bytes.encode(*encode_args) return unicode_or_bytes def native(s, *encoding_opts): """ Convert :py:class:`bytes` or :py:class:`unicode` to the native :py:class:`str` type, using latin1 encoding if conversion is necessary. https://www.python.org/dev/peps/pep-3333/#a-note-on-string-types """ if not isinstance(s, (six.binary_type, six.text_type)): raise TypeError("%r is neither bytes nor unicode" % s) if six.PY3: if isinstance(s, six.binary_type): return s.decode(*encoding_opts) else: if isinstance(s, six.text_type): return s.encode(*encoding_opts) return s def clean_bin(s, keep_spacing=True): """ Cleans binary data to make it safe to display. Args: keep_spacing: If False, tabs and newlines will also be replaced. """ if isinstance(s, six.text_type): if keep_spacing: keep = u" \n\r\t" else: keep = u" " return u"".join( ch if (unicodedata.category(ch)[0] not in "CZ" or ch in keep) else u"." for ch in s ) else: if keep_spacing: keep = (9, 10, 13) # \t, \n, \r, else: keep = () return b"".join( six.int2byte(ch) if (31 < ch < 127 or ch in keep) else b"." for ch in six.iterbytes(s) ) def hexdump(s): """ Returns: A generator of (offset, hex, str) tuples """ for i in range(0, len(s), 16): offset = "{:0=10x}".format(i).encode() part = s[i:i + 16] x = b" ".join("{:0=2x}".format(i).encode() for i in six.iterbytes(part)) x = x.ljust(47) # 16*2 + 15 yield (offset, x, clean_bin(part, False)) def setbit(byte, offset, value): """ Set a bit in a byte to 1 if value is truthy, 0 if not. """ if value: return byte | (1 << offset) else: return byte & ~(1 << offset) def getbit(byte, offset): mask = 1 << offset return bool(byte & mask) class BiDi(object): """ A wee utility class for keeping bi-directional mappings, like field constants in protocols. Names are attributes on the object, dict-like access maps values to names: CONST = BiDi(a=1, b=2) assert CONST.a == 1 assert CONST.get_name(1) == "a" """ def __init__(self, **kwargs): self.names = kwargs self.values = {} for k, v in kwargs.items(): self.values[v] = k if len(self.names) != len(self.values): raise ValueError("Duplicate values not allowed.") def __getattr__(self, k): if k in self.names: return self.names[k] raise AttributeError("No such attribute: %s", k) def get_name(self, n, default=None): return self.values.get(n, default) class Data(object): def __init__(self, name): m = importlib.import_module(name) dirname = os.path.dirname(inspect.getsourcefile(m)) self.dirname = os.path.abspath(dirname) def path(self, path): """ Returns a path to the package data housed at 'path' under this module.Path can be a path to a file, or to a directory. This function will raise ValueError if the path does not exist. """ fullpath = os.path.join(self.dirname, path) if not os.path.exists(fullpath): raise ValueError("dataPath: %s does not exist." % fullpath) return fullpath _label_valid = re.compile(b"(?!-)[A-Z\d-]{1,63}(? 255: return False if host[-1] == b".": host = host[:-1] return all(_label_valid.match(x) for x in host.split(b".")) def is_valid_port(port): return 0 <= port <= 65535 def hostport(scheme, host, port): """ Returns the host component, with a port specifcation if needed. """ if (port, scheme) in [(80, "http"), (443, "https"), (80, b"http"), (443, b"https")]: return host else: if isinstance(host, six.binary_type): return b"%s:%d" % (host, port) else: return "%s:%d" % (host, port) def safe_subn(pattern, repl, target, *args, **kwargs): """ There are Unicode conversion problems with re.subn. We try to smooth that over by casting the pattern and replacement to strings. We really need a better solution that is aware of the actual content ecoding. """ return re.subn(str(pattern), str(repl), target, *args, **kwargs) def bytes_to_escaped_str(data): """ Take bytes and return a safe string that can be displayed to the user. Single quotes are always escaped, double quotes are never escaped: "'" + bytes_to_escaped_str(...) + "'" gives a valid Python string. """ # TODO: We may want to support multi-byte characters without escaping them. # One way to do would be calling .decode("utf8", "backslashreplace") first # and then escaping UTF8 control chars (see clean_bin). if not isinstance(data, bytes): raise ValueError("data must be bytes, but is {}".format(data.__class__.__name__)) # We always insert a double-quote here so that we get a single-quoted string back # https://stackoverflow.com/questions/29019340/why-does-python-use-different-quotes-for-representing-strings-depending-on-their return repr(b'"' + data).lstrip("b")[2:-1] def escaped_str_to_bytes(data): """ Take an escaped string and return the unescaped bytes equivalent. """ if not isinstance(data, six.string_types): if six.PY2: raise ValueError("data must be str or unicode, but is {}".format(data.__class__.__name__)) raise ValueError("data must be str, but is {}".format(data.__class__.__name__)) if six.PY2: if isinstance(data, unicode): data = data.encode("utf8") return data.decode("string-escape") # This one is difficult - we use an undocumented Python API here # as per http://stackoverflow.com/a/23151714/934719 return codecs.escape_decode(data)[0]