from __future__ import unicode_literals import itertools import json import math import operator import re from .utils import ( NO_DEFAULT, ExtractorError, js_to_json, remove_quotes, unified_timestamp, ) from .compat import ( compat_collections_chain_map as ChainMap, compat_itertools_zip_longest as zip_longest, compat_str, ) _NAME_RE = r'[a-zA-Z_$][\w$]*' # (op, definition) in order of binding priority, tightest first # avoid dict to maintain order # definition None => Defined in JSInterpreter._operator _DOT_OPERATORS = ( ('.', None), # TODO: ('?.', None), ) _OPERATORS = ( ('|', operator.or_), ('^', operator.xor), ('&', operator.and_), ('>>', operator.rshift), ('<<', operator.lshift), ('+', operator.add), ('-', operator.sub), ('*', operator.mul), ('/', operator.truediv), ('%', operator.mod), ) _COMP_OPERATORS = ( ('===', operator.is_), ('==', operator.eq), ('!==', operator.is_not), ('!=', operator.ne), ('<=', operator.le), ('>=', operator.ge), ('<', operator.lt), ('>', operator.gt), ) _LOG_OPERATORS = ( ('&', operator.and_), ('|', operator.or_), ('^', operator.xor), ) _SC_OPERATORS = ( ('?', None), ('||', None), ('&&', None), # TODO: ('??', None), ) _OPERATOR_RE = '|'.join(map(lambda x: re.escape(x[0]), _OPERATORS + _LOG_OPERATORS)) _MATCHING_PARENS = dict(zip(*zip('()', '{}', '[]'))) _QUOTES = '\'"' def _ternary(cndn, if_true=True, if_false=False): """Simulate JS's ternary operator (cndn?if_true:if_false)""" if cndn in (False, None, 0, ''): return if_false try: if math.isnan(cndn): # NB: NaN cannot be checked by membership return if_false except TypeError: pass return if_true class JS_Break(ExtractorError): def __init__(self): ExtractorError.__init__(self, 'Invalid break') class JS_Continue(ExtractorError): def __init__(self): ExtractorError.__init__(self, 'Invalid continue') class LocalNameSpace(ChainMap): def __setitem__(self, key, value): for scope in self.maps: if key in scope: scope[key] = value return self.maps[0][key] = value def __delitem__(self, key): raise NotImplementedError('Deleting is not supported') def __repr__(self): return 'LocalNameSpace%s' % (self.maps, ) class JSInterpreter(object): __named_object_counter = 0 def __init__(self, code, objects=None): self.code, self._functions = code, {} self._objects = {} if objects is None else objects class Exception(ExtractorError): def __init__(self, msg, *args, **kwargs): expr = kwargs.pop('expr', None) if expr is not None: msg = '{0} in: {1!r}'.format(msg.rstrip(), expr[:100]) super(JSInterpreter.Exception, self).__init__(msg, *args, **kwargs) def _named_object(self, namespace, obj): self.__named_object_counter += 1 name = '__youtube_dl_jsinterp_obj%d' % (self.__named_object_counter, ) namespace[name] = obj return name @staticmethod def _separate(expr, delim=',', max_split=None, skip_delims=None): if not expr: return counters = {k: 0 for k in _MATCHING_PARENS.values()} start, splits, pos, skipping, delim_len = 0, 0, 0, 0, len(delim) - 1 in_quote, escaping = None, False for idx, char in enumerate(expr): if not in_quote: if char in _MATCHING_PARENS: counters[_MATCHING_PARENS[char]] += 1 elif char in counters: counters[char] -= 1 if not escaping: if char in _QUOTES and in_quote in (char, None): in_quote = None if in_quote else char else: escaping = in_quote and char == '\\' else: escaping = False if char != delim[pos] or any(counters.values()) or in_quote: pos = skipping = 0 continue elif skipping > 0: skipping -= 1 continue elif pos == 0 and skip_delims: here = expr[idx:] for s in skip_delims if isinstance(skip_delims, (list, tuple)) else [skip_delims]: if here.startswith(s) and s: skipping = len(s) - 1 break if skipping > 0: continue if pos < delim_len: pos += 1 continue yield expr[start: idx - delim_len] start, pos = idx + 1, 0 splits += 1 if max_split and splits >= max_split: break yield expr[start:] @classmethod def _separate_at_paren(cls, expr, delim): separated = list(cls._separate(expr, delim, 1)) if len(separated) < 2: raise cls.Exception('No terminating paren {delim} in {expr}'.format(**locals())) return separated[0][1:].strip(), separated[1].strip() @staticmethod def _all_operators(): return itertools.chain( _SC_OPERATORS, _LOG_OPERATORS, _COMP_OPERATORS, _OPERATORS) def _operator(self, op, left_val, right_expr, expr, local_vars, allow_recursion): if op in ('||', '&&'): if (op == '&&') ^ _ternary(left_val): return left_val # short circuiting elif op == '?': right_expr = _ternary(left_val, *self._separate(right_expr, ':', 1)) right_val = self.interpret_expression(right_expr, local_vars, allow_recursion) opfunc = op and next((v for k, v in self._all_operators() if k == op), None) if not opfunc: return right_val try: return opfunc(left_val, right_val) except Exception as e: raise self.Exception('Failed to evaluate {left_val!r} {op} {right_val!r}'.format(**locals()), expr, cause=e) def _index(self, obj, idx): if idx == 'length': return len(obj) try: return obj[int(idx)] if isinstance(obj, list) else obj[idx] except Exception as e: raise self.Exception('Cannot get index {idx}'.format(**locals()), expr=repr(obj), cause=e) def _dump(self, obj, namespace): try: return json.dumps(obj) except TypeError: return self._named_object(namespace, obj) def interpret_statement(self, stmt, local_vars, allow_recursion=100): if allow_recursion < 0: raise self.Exception('Recursion limit reached') allow_recursion -= 1 should_return = False sub_statements = list(self._separate(stmt, ';')) or [''] expr = stmt = sub_statements.pop().strip() for sub_stmt in sub_statements: ret, should_return = self.interpret_statement(sub_stmt, local_vars, allow_recursion) if should_return: return ret, should_return m = re.match(r'(?P(?:var|const|let)\s)|return(?:\s+|$)', stmt) if m: expr = stmt[len(m.group(0)):].strip() should_return = not m.group('var') if not expr: return None, should_return if expr[0] in _QUOTES: inner, outer = self._separate(expr, expr[0], 1) inner = json.loads(js_to_json(inner + expr[0])) # , strict=True)) if not outer: return inner, should_return expr = self._named_object(local_vars, inner) + outer if expr.startswith('new '): obj = expr[4:] if obj.startswith('Date('): left, right = self._separate_at_paren(obj[4:], ')') left = self.interpret_expression(left, local_vars, allow_recursion) expr = unified_timestamp(left, False) if not expr: raise self.Exception('Failed to parse date {left!r}'.format(**locals()), expr=expr) expr = self._dump(int(expr * 1000), local_vars) + right else: raise self.Exception('Unsupported object {obj}'.format(**locals()), expr=expr) if expr.startswith('void '): left = self.interpret_expression(expr[5:], local_vars, allow_recursion) return None, should_return if expr.startswith('{'): inner, outer = self._separate_at_paren(expr, '}') inner, should_abort = self.interpret_statement(inner, local_vars, allow_recursion) if not outer or should_abort: return inner, should_abort or should_return else: expr = self._dump(inner, local_vars) + outer if expr.startswith('('): inner, outer = self._separate_at_paren(expr, ')') inner, should_abort = self.interpret_statement(inner, local_vars, allow_recursion) if not outer or should_abort: return inner, should_abort or should_return else: expr = self._dump(inner, local_vars) + outer if expr.startswith('['): inner, outer = self._separate_at_paren(expr, ']') name = self._named_object(local_vars, [ self.interpret_expression(item, local_vars, allow_recursion) for item in self._separate(inner)]) expr = name + outer m = re.match(r'(?Ptry|finally)\s*|(?:(?Pcatch)|(?Pfor)|(?Pswitch))\s*\(', expr) md = m.groupdict() if m else {} if md.get('try'): if expr[m.end()] == '{': try_expr, expr = self._separate_at_paren(expr[m.end():], '}') else: try_expr, expr = expr[m.end() - 1:], '' ret, should_abort = self.interpret_statement(try_expr, local_vars, allow_recursion) if should_abort: return ret, True ret, should_abort = self.interpret_statement(expr, local_vars, allow_recursion) return ret, should_abort or should_return elif md.get('catch'): # We ignore the catch block _, expr = self._separate_at_paren(expr, '}') ret, should_abort = self.interpret_statement(expr, local_vars, allow_recursion) return ret, should_abort or should_return elif md.get('for'): constructor, remaining = self._separate_at_paren(expr[m.end() - 1:], ')') if remaining.startswith('{'): body, expr = self._separate_at_paren(remaining, '}') else: switch_m = re.match(r'switch\s*\(', remaining) # FIXME if switch_m: switch_val, remaining = self._separate_at_paren(remaining[switch_m.end() - 1:], ')') body, expr = self._separate_at_paren(remaining, '}') body = 'switch(%s){%s}' % (switch_val, body) else: body, expr = remaining, '' start, cndn, increment = self._separate(constructor, ';') self.interpret_expression(start, local_vars, allow_recursion) while True: if not _ternary(self.interpret_expression(cndn, local_vars, allow_recursion)): break try: ret, should_abort = self.interpret_statement(body, local_vars, allow_recursion) if should_abort: return ret, True except JS_Break: break except JS_Continue: pass self.interpret_expression(increment, local_vars, allow_recursion) ret, should_abort = self.interpret_statement(expr, local_vars, allow_recursion) return ret, should_abort or should_return elif md.get('switch'): switch_val, remaining = self._separate_at_paren(expr[m.end() - 1:], ')') switch_val = self.interpret_expression(switch_val, local_vars, allow_recursion) body, expr = self._separate_at_paren(remaining, '}') items = body.replace('default:', 'case default:').split('case ')[1:] for default in (False, True): matched = False for item in items: case, stmt = (i.strip() for i in self._separate(item, ':', 1)) if default: matched = matched or case == 'default' elif not matched: matched = (case != 'default' and switch_val == self.interpret_expression(case, local_vars, allow_recursion)) if not matched: continue try: ret, should_abort = self.interpret_statement(stmt, local_vars, allow_recursion) if should_abort: return ret except JS_Break: break if matched: break ret, should_abort = self.interpret_statement(expr, local_vars, allow_recursion) return ret, should_abort or should_return # Comma separated statements sub_expressions = list(self._separate(expr)) if len(sub_expressions) > 1: for sub_expr in sub_expressions: ret, should_abort = self.interpret_statement(sub_expr, local_vars, allow_recursion) if should_abort: return ret, True return ret, False for m in re.finditer(r'''(?x) (?P\+\+|--)(?P{_NAME_RE})| (?P{_NAME_RE})(?P\+\+|--)'''.format(**globals()), expr): var = m.group('var1') or m.group('var2') start, end = m.span() sign = m.group('pre_sign') or m.group('post_sign') ret = local_vars[var] local_vars[var] += 1 if sign[0] == '+' else -1 if m.group('pre_sign'): ret = local_vars[var] expr = expr[:start] + self._dump(ret, local_vars) + expr[end:] if not expr: return None, should_return m = re.match(r'''(?x) (?P (?P{_NAME_RE})(?:\[(?P[^\]]+?)\])?\s* (?P{_OPERATOR_RE})? =(?P.*)$ )|(?P (?!if|return|true|false|null|undefined)(?P{_NAME_RE})$ )|(?P (?P{_NAME_RE})\[(?P.+)\]$ )|(?P (?P{_NAME_RE})(?:\.(?P[^(]+)|\[(?P[^\]]+)\])\s* )|(?P (?P{_NAME_RE})\((?P.*)\)$ )'''.format(**globals()), expr) md = m.groupdict() if m else {} if md.get('assign'): left_val = local_vars.get(m.group('out')) if not m.group('index'): local_vars[m.group('out')] = self._operator( m.group('op'), left_val, m.group('expr'), expr, local_vars, allow_recursion) return local_vars[m.group('out')], should_return elif left_val is None: raise self.Exception('Cannot index undefined variable ' + m.group('out'), expr=expr) idx = self.interpret_expression(m.group('index'), local_vars, allow_recursion) if not isinstance(idx, (int, float)): raise self.Exception('List index %s must be integer' % (idx, ), expr=expr) idx = int(idx) left_val[idx] = self._operator( m.group('op'), left_val[idx], m.group('expr'), expr, local_vars, allow_recursion) return left_val[idx], should_return elif expr.isdigit(): return int(expr), should_return elif expr == 'break': raise JS_Break() elif expr == 'continue': raise JS_Continue() elif md.get('return'): return local_vars[m.group('name')], should_return try: ret = json.loads(js_to_json(expr)) # strict=True) if not md.get('attribute'): return ret, should_return except ValueError: pass if md.get('indexing'): val = local_vars[m.group('in')] idx = self.interpret_expression(m.group('idx'), local_vars, allow_recursion) return self._index(val, idx), should_return for op, _ in self._all_operators(): # hackety: have higher priority than <>, but don't confuse them skip_delim = (op + op) if op in ('<', '>') else None separated = list(self._separate(expr, op, skip_delims=skip_delim)) if len(separated) < 2: continue right_expr = separated.pop() while op == '-' and len(separated) > 1 and not separated[-1].strip(): right_expr = '-' + right_expr separated.pop() left_val = self.interpret_expression(op.join(separated), local_vars, allow_recursion) return self._operator(op, 0 if left_val is None else left_val, right_expr, expr, local_vars, allow_recursion), should_return if md.get('attribute'): variable = m.group('var') member = m.group('member') if not member: member = self.interpret_expression(m.group('member2'), local_vars, allow_recursion) arg_str = expr[m.end():] if arg_str.startswith('('): arg_str, remaining = self._separate_at_paren(arg_str, ')') else: arg_str, remaining = None, arg_str def assertion(cndn, msg): """ assert, but without risk of getting optimized out """ if not cndn: raise ExtractorError('{member} {msg}'.format(**locals()), expr=expr) def eval_method(): if (variable, member) == ('console', 'debug'): return types = { 'String': compat_str, 'Math': float, } obj = local_vars.get(variable, types.get(variable, NO_DEFAULT)) if obj is NO_DEFAULT: if variable not in self._objects: self._objects[variable] = self.extract_object(variable) obj = self._objects[variable] # Member access if arg_str is None: return self._index(obj, member) # Function call argvals = [ self.interpret_expression(v, local_vars, allow_recursion) for v in self._separate(arg_str)] if obj == compat_str: if member == 'fromCharCode': assertion(argvals, 'takes one or more arguments') return ''.join(map(chr, argvals)) raise self.Exception('Unsupported string method ' + member, expr=expr) elif obj == float: if member == 'pow': assertion(len(argvals) == 2, 'takes two arguments') return argvals[0] ** argvals[1] raise self.Exception('Unsupported Math method ' + member, expr=expr) if member == 'split': assertion(argvals, 'takes one or more arguments') assertion(len(argvals) == 1, 'with limit argument is not implemented') return obj.split(argvals[0]) if argvals[0] else list(obj) elif member == 'join': assertion(isinstance(obj, list), 'must be applied on a list') assertion(len(argvals) == 1, 'takes exactly one argument') return argvals[0].join(obj) elif member == 'reverse': assertion(not argvals, 'does not take any arguments') obj.reverse() return obj elif member == 'slice': assertion(isinstance(obj, list), 'must be applied on a list') assertion(len(argvals) == 1, 'takes exactly one argument') return obj[argvals[0]:] elif member == 'splice': assertion(isinstance(obj, list), 'must be applied on a list') assertion(argvals, 'takes one or more arguments') index, howMany = map(int, (argvals + [len(obj)])[:2]) if index < 0: index += len(obj) add_items = argvals[2:] res = [] for i in range(index, min(index + howMany, len(obj))): res.append(obj.pop(index)) for i, item in enumerate(add_items): obj.insert(index + i, item) return res elif member == 'unshift': assertion(isinstance(obj, list), 'must be applied on a list') assertion(argvals, 'takes one or more arguments') for item in reversed(argvals): obj.insert(0, item) return obj elif member == 'pop': assertion(isinstance(obj, list), 'must be applied on a list') assertion(not argvals, 'does not take any arguments') if not obj: return return obj.pop() elif member == 'push': assertion(argvals, 'takes one or more arguments') obj.extend(argvals) return obj elif member == 'forEach': assertion(argvals, 'takes one or more arguments') assertion(len(argvals) <= 2, 'takes at-most 2 arguments') f, this = (argvals + [''])[:2] return [f((item, idx, obj), {'this': this}, allow_recursion) for idx, item in enumerate(obj)] elif member == 'indexOf': assertion(argvals, 'takes one or more arguments') assertion(len(argvals) <= 2, 'takes at-most 2 arguments') idx, start = (argvals + [0])[:2] try: return obj.index(idx, start) except ValueError: return -1 idx = int(member) if isinstance(obj, list) else member return obj[idx](argvals, allow_recursion=allow_recursion) if remaining: ret, should_abort = self.interpret_statement( self._named_object(local_vars, eval_method()) + remaining, local_vars, allow_recursion) return ret, should_return or should_abort else: return eval_method(), should_return elif md.get('function'): fname = m.group('fname') argvals = [self.interpret_expression(v, local_vars, allow_recursion) for v in self._separate(m.group('args'))] if fname in local_vars: return local_vars[fname](argvals, allow_recursion=allow_recursion), should_return elif fname not in self._functions: self._functions[fname] = self.extract_function(fname) return self._functions[fname](argvals, allow_recursion=allow_recursion), should_return raise self.Exception( 'Unsupported JS expression ' + (expr[:40] if expr != stmt else ''), expr=stmt) def interpret_expression(self, expr, local_vars, allow_recursion): ret, should_return = self.interpret_statement(expr, local_vars, allow_recursion) if should_return: raise self.Exception('Cannot return from an expression', expr) return ret def extract_object(self, objname): _FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')''' obj = {} obj_m = re.search( r'''(?x) (?(%s\s*:\s*function\s*\(.*?\)\s*{.*?}(?:,\s*)?)*) }\s*; ''' % (re.escape(objname), _FUNC_NAME_RE), self.code) if not obj_m: raise self.Exception('Could not find object ' + objname) fields = obj_m.group('fields') # Currently, it only supports function definitions fields_m = re.finditer( r'''(?x) (?P%s)\s*:\s*function\s*\((?P(?:%s|,)*)\){(?P[^}]+)} ''' % (_FUNC_NAME_RE, _NAME_RE), fields) for f in fields_m: argnames = self.build_arglist(f.group('args')) obj[remove_quotes(f.group('key'))] = self.build_function(argnames, f.group('code')) return obj def extract_function_code(self, funcname): """ @returns argnames, code """ func_m = re.search( r'''(?xs) (?: function\s+%(name)s| [{;,]\s*%(name)s\s*=\s*function| (?:var|const|let)\s+%(name)s\s*=\s*function )\s* \((?P[^)]*)\)\s* (?P{.+})''' % {'name': re.escape(funcname)}, self.code) code, _ = self._separate_at_paren(func_m.group('code'), '}') # refine the match if func_m is None: raise self.Exception('Could not find JS function "{funcname}"'.format(**locals())) return self.build_arglist(func_m.group('args')), code def extract_function(self, funcname): return self.extract_function_from_code(*self.extract_function_code(funcname)) def extract_function_from_code(self, argnames, code, *global_stack): local_vars = {} while True: mobj = re.search(r'function\((?P[^)]*)\)\s*{', code) if mobj is None: break start, body_start = mobj.span() body, remaining = self._separate_at_paren(code[body_start - 1:], '}') name = self._named_object( local_vars, self.extract_function_from_code( self.build_arglist(mobj.group('args')), body, local_vars, *global_stack)) code = code[:start] + name + remaining return self.build_function(argnames, code, local_vars, *global_stack) def call_function(self, funcname, *args): return self.extract_function(funcname)(args) @classmethod def build_arglist(cls, arg_text): if not arg_text: return [] return list(filter(None, (x.strip() or None for x in cls._separate(arg_text)))) def build_function(self, argnames, code, *global_stack): global_stack = list(global_stack) or [{}] argnames = tuple(argnames) def resf(args, kwargs={}, allow_recursion=100): global_stack[0].update( zip_longest(argnames, args, fillvalue=None)) global_stack[0].update(kwargs) var_stack = LocalNameSpace(*global_stack) ret, should_abort = self.interpret_statement(code.replace('\n', ''), var_stack, allow_recursion - 1) if should_abort: return ret return resf