import operator import os import abc import pyparsing as pp import six from six.moves import reduce from netlib import strutils from netlib import human from . import generators, exceptions class Settings(object): def __init__( self, is_client=False, staticdir=None, unconstrained_file_access=False, request_host=None, websocket_key=None, protocol=None, ): self.is_client = is_client self.staticdir = staticdir self.unconstrained_file_access = unconstrained_file_access self.request_host = request_host self.websocket_key = websocket_key # TODO: refactor this into the protocol self.protocol = protocol Sep = pp.Optional(pp.Literal(":")).suppress() v_integer = pp.Word(pp.nums)\ .setName("integer")\ .setParseAction(lambda toks: int(toks[0])) v_literal = pp.MatchFirst( [ pp.QuotedString( "\"", unquoteResults=True, multiline=True ), pp.QuotedString( "'", unquoteResults=True, multiline=True ), ] ) v_naked_literal = pp.MatchFirst( [ v_literal, pp.Word("".join(i for i in pp.printables if i not in ",:\n@\'\"")) ] ) class Token(object): """ A token in the specification language. Tokens are immutable. The token classes have no meaning in and of themselves, and are combined into Components and Actions to build the language. """ __metaclass__ = abc.ABCMeta @classmethod def expr(cls): # pragma: no cover """ A parse expression. """ return None @abc.abstractmethod def spec(self): # pragma: no cover """ A parseable specification for this token. """ return None @property def unique_name(self): """ Controls uniqueness constraints for tokens. No two tokens with the same name will be allowed. If no uniquness should be applied, this should be None. """ return self.__class__.__name__.lower() def resolve(self, settings_, msg_): """ Resolves this token to ready it for transmission. This means that the calculated offsets of actions are fixed. settings: a language.Settings instance msg: The containing message """ return self def __repr__(self): return self.spec() class _TokValueLiteral(Token): def __init__(self, val): self.val = strutils.escaped_str_to_bytes(val) def get_generator(self, settings_): return self.val def freeze(self, settings_): return self class TokValueLiteral(_TokValueLiteral): """ A literal with Python-style string escaping """ @classmethod def expr(cls): e = v_literal.copy() return e.setParseAction(cls.parseAction) @classmethod def parseAction(cls, x): v = cls(*x) return v def spec(self): inner = strutils.bytes_to_escaped_str(self.val) inner = inner.replace(r"\'", r"\x27") return "'" + inner + "'" class TokValueNakedLiteral(_TokValueLiteral): @classmethod def expr(cls): e = v_naked_literal.copy() return e.setParseAction(lambda x: cls(*x)) def spec(self): return strutils.bytes_to_escaped_str(self.val) class TokValueGenerate(Token): def __init__(self, usize, unit, datatype): if not unit: unit = "b" self.usize, self.unit, self.datatype = usize, unit, datatype def bytes(self): return self.usize * human.SIZE_UNITS[self.unit] def get_generator(self, settings_): return generators.RandomGenerator(self.datatype, self.bytes()) def freeze(self, settings): g = self.get_generator(settings) return TokValueLiteral(strutils.bytes_to_escaped_str(g[:])) @classmethod def expr(cls): e = pp.Literal("@").suppress() + v_integer u = reduce( operator.or_, [pp.Literal(i) for i in human.SIZE_UNITS.keys()] ).leaveWhitespace() e = e + pp.Optional(u, default=None) s = pp.Literal(",").suppress() s += reduce( operator.or_, [pp.Literal(i) for i in generators.DATATYPES.keys()] ) e += pp.Optional(s, default="bytes") return e.setParseAction(lambda x: cls(*x)) def spec(self): s = "@%s" % self.usize if self.unit != "b": s += self.unit if self.datatype != "bytes": s += ",%s" % self.datatype return s class TokValueFile(Token): def __init__(self, path): self.path = str(path) @classmethod def expr(cls): e = pp.Literal("<").suppress() e = e + v_naked_literal return e.setParseAction(lambda x: cls(*x)) def freeze(self, settings_): return self def get_generator(self, settings): if not settings.staticdir: raise exceptions.FileAccessDenied("File access disabled.") s = os.path.expanduser(self.path) s = os.path.normpath( os.path.abspath(os.path.join(settings.staticdir, s)) ) uf = settings.unconstrained_file_access if not uf and not s.startswith(settings.staticdir): raise exceptions.FileAccessDenied( "File access outside of configured directory" ) if not os.path.isfile(s): raise exceptions.FileAccessDenied("File not readable") return generators.FileGenerator(s) def spec(self): return "<'%s'" % self.path TokValue = pp.MatchFirst( [ TokValueGenerate.expr(), TokValueFile.expr(), TokValueLiteral.expr() ] ) TokNakedValue = pp.MatchFirst( [ TokValueGenerate.expr(), TokValueFile.expr(), TokValueLiteral.expr(), TokValueNakedLiteral.expr(), ] ) TokOffset = pp.MatchFirst( [ v_integer, pp.Literal("r"), pp.Literal("a") ] ) class _Component(Token): """ A value component of the primary specification of an message. Components produce byte values describing the bytes of the message. """ def values(self, settings): # pragma: no cover """ A sequence of values, which can either be strings or generators. """ pass def string(self, settings=None): """ A bytestring representation of the object. """ return b"".join(i[:] for i in self.values(settings or {})) class KeyValue(_Component): """ A key/value pair. cls.preamble: leader """ def __init__(self, key, value): self.key, self.value = key, value @classmethod def expr(cls): e = pp.Literal(cls.preamble).suppress() e += TokValue e += pp.Literal("=").suppress() e += TokValue return e.setParseAction(lambda x: cls(*x)) def spec(self): return "%s%s=%s" % (self.preamble, self.key.spec(), self.value.spec()) def freeze(self, settings): return self.__class__( self.key.freeze(settings), self.value.freeze(settings) ) class CaselessLiteral(_Component): """ A caseless token that can take only one value. """ def __init__(self, value): self.value = value @classmethod def expr(cls): spec = pp.CaselessLiteral(cls.TOK) spec = spec.setParseAction(lambda x: cls(*x)) return spec def values(self, settings): return self.TOK def spec(self): return self.TOK def freeze(self, settings_): return self class OptionsOrValue(_Component): """ Can be any of a specified set of options, or a value specifier. """ preamble = "" options = [] def __init__(self, value): # If it's a string, we were passed one of the options, so we lower-case # it to be canonical. The user can specify a different case by using a # string value literal. self.option_used = False if isinstance(value, six.string_types): for i in self.options: # Find the exact option value in a case-insensitive way if i.lower() == value.lower(): self.option_used = True value = TokValueLiteral(i) break self.value = value @classmethod def expr(cls): parts = [pp.CaselessLiteral(i) for i in cls.options] m = pp.MatchFirst(parts) spec = m | TokValue.copy() spec = spec.setParseAction(lambda x: cls(*x)) if cls.preamble: spec = pp.Literal(cls.preamble).suppress() + spec return spec def values(self, settings): return [ self.value.get_generator(settings) ] def spec(self): s = self.value.spec() if s[1:-1].lower() in self.options: s = s[1:-1].lower() return "%s%s" % (self.preamble, s) def freeze(self, settings): return self.__class__(self.value.freeze(settings)) class Integer(_Component): bounds = (None, None) preamble = "" def __init__(self, value): v = int(value) outofbounds = any([ self.bounds[0] is not None and v < self.bounds[0], self.bounds[1] is not None and v > self.bounds[1] ]) if outofbounds: raise exceptions.ParseException( "Integer value must be between %s and %s." % self.bounds, 0, 0 ) self.value = str(value) @classmethod def expr(cls): e = v_integer.copy() if cls.preamble: e = pp.Literal(cls.preamble).suppress() + e return e.setParseAction(lambda x: cls(*x)) def values(self, settings): return self.value def spec(self): return "%s%s" % (self.preamble, self.value) def freeze(self, settings_): return self class Value(_Component): """ A value component lead by an optional preamble. """ preamble = "" def __init__(self, value): self.value = value @classmethod def expr(cls): e = (TokValue | TokNakedValue) if cls.preamble: e = pp.Literal(cls.preamble).suppress() + e return e.setParseAction(lambda x: cls(*x)) def values(self, settings): return [self.value.get_generator(settings)] def spec(self): return "%s%s" % (self.preamble, self.value.spec()) def freeze(self, settings): return self.__class__(self.value.freeze(settings)) class FixedLengthValue(Value): """ A value component lead by an optional preamble. """ preamble = "" length = None def __init__(self, value): Value.__init__(self, value) lenguess = None try: lenguess = len(value.get_generator(Settings())) except exceptions.RenderError: pass # This check will fail if we know the length upfront if lenguess is not None and lenguess != self.length: raise exceptions.RenderError( "Invalid value length: '%s' is %s bytes, should be %s." % ( self.spec(), lenguess, self.length ) ) def values(self, settings): ret = Value.values(self, settings) l = sum(len(i) for i in ret) # This check will fail if we don't know the length upfront - i.e. for # file inputs if l != self.length: raise exceptions.RenderError( "Invalid value length: '%s' is %s bytes, should be %s." % ( self.spec(), l, self.length ) ) return ret class Boolean(_Component): """ A boolean flag. name = true -name = false """ name = "" def __init__(self, value): self.value = value @classmethod def expr(cls): e = pp.Optional(pp.Literal("-"), default=True) e += pp.Literal(cls.name).suppress() def parse(s_, loc_, toks): val = True if toks[0] == "-": val = False return cls(val) return e.setParseAction(parse) def spec(self): return "%s%s" % ("-" if not self.value else "", self.name) class IntField(_Component): """ An integer field, where values can optionally specified by name. """ names = {} max = 16 preamble = "" def __init__(self, value): self.origvalue = value self.value = self.names.get(value, value) if self.value > self.max: raise exceptions.ParseException( "Value can't exceed %s" % self.max, 0, 0 ) @classmethod def expr(cls): parts = [pp.CaselessLiteral(i) for i in cls.names.keys()] m = pp.MatchFirst(parts) spec = m | v_integer.copy() spec = spec.setParseAction(lambda x: cls(*x)) if cls.preamble: spec = pp.Literal(cls.preamble).suppress() + spec return spec def values(self, settings): return [str(self.value)] def spec(self): return "%s%s" % (self.preamble, self.origvalue) class NestedMessage(Token): """ A nested message, as an escaped string with a preamble. """ preamble = "" nest_type = None def __init__(self, value): Token.__init__(self) self.value = value try: self.parsed = self.nest_type( self.nest_type.expr().parseString( value.val, parseAll=True ) ) except pp.ParseException as v: raise exceptions.ParseException(v.msg, v.line, v.col) @classmethod def expr(cls): e = pp.Literal(cls.preamble).suppress() e = e + TokValueLiteral.expr() return e.setParseAction(lambda x: cls(*x)) def values(self, settings): return [ self.value.get_generator(settings), ] def spec(self): return "%s%s" % (self.preamble, self.value.spec()) def freeze(self, settings): f = self.parsed.freeze(settings).spec() return self.__class__(TokValueLiteral(strutils.bytes_to_escaped_str(f)))