X-Git-Url: https://git.rapsys.eu/youtubedl/blobdiff_plain/5d3bcae50f6f7185984ffdf960a0bc5444b3d556..a4f82408d9a3d921d9c2af7e4d757f44737dc7ea:/youtube_dl/swfinterp.py

diff --git a/youtube_dl/swfinterp.py b/youtube_dl/swfinterp.py
new file mode 100644
index 0000000..b63c65b
--- /dev/null
+++ b/youtube_dl/swfinterp.py
@@ -0,0 +1,609 @@
+from __future__ import unicode_literals
+
+import collections
+import io
+import zlib
+
+from .utils import (
+    compat_str,
+    ExtractorError,
+    struct_unpack,
+)
+
+
+def _extract_tags(file_contents):
+    if file_contents[1:3] != b'WS':
+        raise ExtractorError(
+            'Not an SWF file; header is %r' % file_contents[:3])
+    if file_contents[:1] == b'C':
+        content = zlib.decompress(file_contents[8:])
+    else:
+        raise NotImplementedError(
+            'Unsupported compression format %r' %
+            file_contents[:1])
+
+    # Determine number of bits in framesize rectangle
+    framesize_nbits = struct_unpack('!B', content[:1])[0] >> 3
+    framesize_len = (5 + 4 * framesize_nbits + 7) // 8
+
+    pos = framesize_len + 2 + 2
+    while pos < len(content):
+        header16 = struct_unpack('<H', content[pos:pos + 2])[0]
+        pos += 2
+        tag_code = header16 >> 6
+        tag_len = header16 & 0x3f
+        if tag_len == 0x3f:
+            tag_len = struct_unpack('<I', content[pos:pos + 4])[0]
+            pos += 4
+        assert pos + tag_len <= len(content), \
+            ('Tag %d ends at %d+%d - that\'s longer than the file (%d)'
+                % (tag_code, pos, tag_len, len(content)))
+        yield (tag_code, content[pos:pos + tag_len])
+        pos += tag_len
+
+
+class _AVMClass_Object(object):
+    def __init__(self, avm_class):
+        self.avm_class = avm_class
+
+    def __repr__(self):
+        return '%s#%x' % (self.avm_class.name, id(self))
+
+
+class _ScopeDict(dict):
+    def __init__(self, avm_class):
+        super(_ScopeDict, self).__init__()
+        self.avm_class = avm_class
+
+    def __repr__(self):
+        return '%s__Scope(%s)' % (
+            self.avm_class.name,
+            super(_ScopeDict, self).__repr__())
+
+
+class _AVMClass(object):
+    def __init__(self, name_idx, name):
+        self.name_idx = name_idx
+        self.name = name
+        self.method_names = {}
+        self.method_idxs = {}
+        self.methods = {}
+        self.method_pyfunctions = {}
+
+        self.variables = _ScopeDict(self)
+
+    def make_object(self):
+        return _AVMClass_Object(self)
+
+    def __repr__(self):
+        return '_AVMClass(%s)' % (self.name)
+
+    def register_methods(self, methods):
+        self.method_names.update(methods.items())
+        self.method_idxs.update(dict(
+            (idx, name)
+            for name, idx in methods.items()))
+
+
+class _Multiname(object):
+    def __init__(self, kind):
+        self.kind = kind
+
+    def __repr__(self):
+        return '[MULTINAME kind: 0x%x]' % self.kind
+
+
+def _read_int(reader):
+    res = 0
+    shift = 0
+    for _ in range(5):
+        buf = reader.read(1)
+        assert len(buf) == 1
+        b = struct_unpack('<B', buf)[0]
+        res = res | ((b & 0x7f) << shift)
+        if b & 0x80 == 0:
+            break
+        shift += 7
+    return res
+
+
+def _u30(reader):
+    res = _read_int(reader)
+    assert res & 0xf0000000 == 0
+    return res
+_u32 = _read_int
+
+
+def _s32(reader):
+    v = _read_int(reader)
+    if v & 0x80000000 != 0:
+        v = - ((v ^ 0xffffffff) + 1)
+    return v
+
+
+def _s24(reader):
+    bs = reader.read(3)
+    assert len(bs) == 3
+    last_byte = b'\xff' if (ord(bs[2:3]) >= 0x80) else b'\x00'
+    return struct_unpack('<i', bs + last_byte)[0]
+
+
+def _read_string(reader):
+    slen = _u30(reader)
+    resb = reader.read(slen)
+    assert len(resb) == slen
+    return resb.decode('utf-8')
+
+
+def _read_bytes(count, reader):
+    assert count >= 0
+    resb = reader.read(count)
+    assert len(resb) == count
+    return resb
+
+
+def _read_byte(reader):
+    resb = _read_bytes(1, reader=reader)
+    res = struct_unpack('<B', resb)[0]
+    return res
+
+
+class SWFInterpreter(object):
+    def __init__(self, file_contents):
+        code_tag = next(tag
+                        for tag_code, tag in _extract_tags(file_contents)
+                        if tag_code == 82)
+        p = code_tag.index(b'\0', 4) + 1
+        code_reader = io.BytesIO(code_tag[p:])
+
+        # Parse ABC (AVM2 ByteCode)
+
+        # Define a couple convenience methods
+        u30 = lambda *args: _u30(*args, reader=code_reader)
+        s32 = lambda *args: _s32(*args, reader=code_reader)
+        u32 = lambda *args: _u32(*args, reader=code_reader)
+        read_bytes = lambda *args: _read_bytes(*args, reader=code_reader)
+        read_byte = lambda *args: _read_byte(*args, reader=code_reader)
+
+        # minor_version + major_version
+        read_bytes(2 + 2)
+
+        # Constant pool
+        int_count = u30()
+        for _c in range(1, int_count):
+            s32()
+        uint_count = u30()
+        for _c in range(1, uint_count):
+            u32()
+        double_count = u30()
+        read_bytes(max(0, (double_count - 1)) * 8)
+        string_count = u30()
+        self.constant_strings = ['']
+        for _c in range(1, string_count):
+            s = _read_string(code_reader)
+            self.constant_strings.append(s)
+        namespace_count = u30()
+        for _c in range(1, namespace_count):
+            read_bytes(1)  # kind
+            u30()  # name
+        ns_set_count = u30()
+        for _c in range(1, ns_set_count):
+            count = u30()
+            for _c2 in range(count):
+                u30()
+        multiname_count = u30()
+        MULTINAME_SIZES = {
+            0x07: 2,  # QName
+            0x0d: 2,  # QNameA
+            0x0f: 1,  # RTQName
+            0x10: 1,  # RTQNameA
+            0x11: 0,  # RTQNameL
+            0x12: 0,  # RTQNameLA
+            0x09: 2,  # Multiname
+            0x0e: 2,  # MultinameA
+            0x1b: 1,  # MultinameL
+            0x1c: 1,  # MultinameLA
+        }
+        self.multinames = ['']
+        for _c in range(1, multiname_count):
+            kind = u30()
+            assert kind in MULTINAME_SIZES, 'Invalid multiname kind %r' % kind
+            if kind == 0x07:
+                u30()  # namespace_idx
+                name_idx = u30()
+                self.multinames.append(self.constant_strings[name_idx])
+            else:
+                self.multinames.append(_Multiname(kind))
+                for _c2 in range(MULTINAME_SIZES[kind]):
+                    u30()
+
+        # Methods
+        method_count = u30()
+        MethodInfo = collections.namedtuple(
+            'MethodInfo',
+            ['NEED_ARGUMENTS', 'NEED_REST'])
+        method_infos = []
+        for method_id in range(method_count):
+            param_count = u30()
+            u30()  # return type
+            for _ in range(param_count):
+                u30()  # param type
+            u30()  # name index (always 0 for youtube)
+            flags = read_byte()
+            if flags & 0x08 != 0:
+                # Options present
+                option_count = u30()
+                for c in range(option_count):
+                    u30()  # val
+                    read_bytes(1)  # kind
+            if flags & 0x80 != 0:
+                # Param names present
+                for _ in range(param_count):
+                    u30()  # param name
+            mi = MethodInfo(flags & 0x01 != 0, flags & 0x04 != 0)
+            method_infos.append(mi)
+
+        # Metadata
+        metadata_count = u30()
+        for _c in range(metadata_count):
+            u30()  # name
+            item_count = u30()
+            for _c2 in range(item_count):
+                u30()  # key
+                u30()  # value
+
+        def parse_traits_info():
+            trait_name_idx = u30()
+            kind_full = read_byte()
+            kind = kind_full & 0x0f
+            attrs = kind_full >> 4
+            methods = {}
+            if kind in [0x00, 0x06]:  # Slot or Const
+                u30()  # Slot id
+                u30()  # type_name_idx
+                vindex = u30()
+                if vindex != 0:
+                    read_byte()  # vkind
+            elif kind in [0x01, 0x02, 0x03]:  # Method / Getter / Setter
+                u30()  # disp_id
+                method_idx = u30()
+                methods[self.multinames[trait_name_idx]] = method_idx
+            elif kind == 0x04:  # Class
+                u30()  # slot_id
+                u30()  # classi
+            elif kind == 0x05:  # Function
+                u30()  # slot_id
+                function_idx = u30()
+                methods[function_idx] = self.multinames[trait_name_idx]
+            else:
+                raise ExtractorError('Unsupported trait kind %d' % kind)
+
+            if attrs & 0x4 != 0:  # Metadata present
+                metadata_count = u30()
+                for _c3 in range(metadata_count):
+                    u30()  # metadata index
+
+            return methods
+
+        # Classes
+        class_count = u30()
+        classes = []
+        for class_id in range(class_count):
+            name_idx = u30()
+
+            cname = self.multinames[name_idx]
+            avm_class = _AVMClass(name_idx, cname)
+            classes.append(avm_class)
+
+            u30()  # super_name idx
+            flags = read_byte()
+            if flags & 0x08 != 0:  # Protected namespace is present
+                u30()  # protected_ns_idx
+            intrf_count = u30()
+            for _c2 in range(intrf_count):
+                u30()
+            u30()  # iinit
+            trait_count = u30()
+            for _c2 in range(trait_count):
+                trait_methods = parse_traits_info()
+                avm_class.register_methods(trait_methods)
+
+        assert len(classes) == class_count
+        self._classes_by_name = dict((c.name, c) for c in classes)
+
+        for avm_class in classes:
+            u30()  # cinit
+            trait_count = u30()
+            for _c2 in range(trait_count):
+                trait_methods = parse_traits_info()
+                avm_class.register_methods(trait_methods)
+
+        # Scripts
+        script_count = u30()
+        for _c in range(script_count):
+            u30()  # init
+            trait_count = u30()
+            for _c2 in range(trait_count):
+                parse_traits_info()
+
+        # Method bodies
+        method_body_count = u30()
+        Method = collections.namedtuple('Method', ['code', 'local_count'])
+        for _c in range(method_body_count):
+            method_idx = u30()
+            u30()  # max_stack
+            local_count = u30()
+            u30()  # init_scope_depth
+            u30()  # max_scope_depth
+            code_length = u30()
+            code = read_bytes(code_length)
+            for avm_class in classes:
+                if method_idx in avm_class.method_idxs:
+                    m = Method(code, local_count)
+                    avm_class.methods[avm_class.method_idxs[method_idx]] = m
+            exception_count = u30()
+            for _c2 in range(exception_count):
+                u30()  # from
+                u30()  # to
+                u30()  # target
+                u30()  # exc_type
+                u30()  # var_name
+            trait_count = u30()
+            for _c2 in range(trait_count):
+                parse_traits_info()
+
+        assert p + code_reader.tell() == len(code_tag)
+
+    def extract_class(self, class_name):
+        try:
+            return self._classes_by_name[class_name]
+        except KeyError:
+            raise ExtractorError('Class %r not found' % class_name)
+
+    def extract_function(self, avm_class, func_name):
+        if func_name in avm_class.method_pyfunctions:
+            return avm_class.method_pyfunctions[func_name]
+        if func_name in self._classes_by_name:
+            return self._classes_by_name[func_name].make_object()
+        if func_name not in avm_class.methods:
+            raise ExtractorError('Cannot find function %s.%s' % (
+                avm_class.name, func_name))
+        m = avm_class.methods[func_name]
+
+        def resfunc(args):
+            # Helper functions
+            coder = io.BytesIO(m.code)
+            s24 = lambda: _s24(coder)
+            u30 = lambda: _u30(coder)
+
+            registers = [avm_class.variables] + list(args) + [None] * m.local_count
+            stack = []
+            scopes = collections.deque([
+                self._classes_by_name, avm_class.variables])
+            while True:
+                opcode = _read_byte(coder)
+                if opcode == 17:  # iftrue
+                    offset = s24()
+                    value = stack.pop()
+                    if value:
+                        coder.seek(coder.tell() + offset)
+                elif opcode == 18:  # iffalse
+                    offset = s24()
+                    value = stack.pop()
+                    if not value:
+                        coder.seek(coder.tell() + offset)
+                elif opcode == 36:  # pushbyte
+                    v = _read_byte(coder)
+                    stack.append(v)
+                elif opcode == 42:  # dup
+                    value = stack[-1]
+                    stack.append(value)
+                elif opcode == 44:  # pushstring
+                    idx = u30()
+                    stack.append(self.constant_strings[idx])
+                elif opcode == 48:  # pushscope
+                    new_scope = stack.pop()
+                    scopes.append(new_scope)
+                elif opcode == 66:  # construct
+                    arg_count = u30()
+                    args = list(reversed(
+                        [stack.pop() for _ in range(arg_count)]))
+                    obj = stack.pop()
+                    res = obj.avm_class.make_object()
+                    stack.append(res)
+                elif opcode == 70:  # callproperty
+                    index = u30()
+                    mname = self.multinames[index]
+                    arg_count = u30()
+                    args = list(reversed(
+                        [stack.pop() for _ in range(arg_count)]))
+                    obj = stack.pop()
+
+                    if isinstance(obj, _AVMClass_Object):
+                        func = self.extract_function(obj.avm_class, mname)
+                        res = func(args)
+                        stack.append(res)
+                        continue
+                    elif isinstance(obj, _ScopeDict):
+                        if mname in obj.avm_class.method_names:
+                            func = self.extract_function(obj.avm_class, mname)
+                            res = func(args)
+                        else:
+                            res = obj[mname]
+                        stack.append(res)
+                        continue
+                    elif isinstance(obj, compat_str):
+                        if mname == 'split':
+                            assert len(args) == 1
+                            assert isinstance(args[0], compat_str)
+                            if args[0] == '':
+                                res = list(obj)
+                            else:
+                                res = obj.split(args[0])
+                            stack.append(res)
+                            continue
+                    elif isinstance(obj, list):
+                        if mname == 'slice':
+                            assert len(args) == 1
+                            assert isinstance(args[0], int)
+                            res = obj[args[0]:]
+                            stack.append(res)
+                            continue
+                        elif mname == 'join':
+                            assert len(args) == 1
+                            assert isinstance(args[0], compat_str)
+                            res = args[0].join(obj)
+                            stack.append(res)
+                            continue
+                    raise NotImplementedError(
+                        'Unsupported property %r on %r'
+                        % (mname, obj))
+                elif opcode == 72:  # returnvalue
+                    res = stack.pop()
+                    return res
+                elif opcode == 74:  # constructproperty
+                    index = u30()
+                    arg_count = u30()
+                    args = list(reversed(
+                        [stack.pop() for _ in range(arg_count)]))
+                    obj = stack.pop()
+
+                    mname = self.multinames[index]
+                    assert isinstance(obj, _AVMClass)
+
+                    # We do not actually call the constructor for now;
+                    # we just pretend it does nothing
+                    stack.append(obj.make_object())
+                elif opcode == 79:  # callpropvoid
+                    index = u30()
+                    mname = self.multinames[index]
+                    arg_count = u30()
+                    args = list(reversed(
+                        [stack.pop() for _ in range(arg_count)]))
+                    obj = stack.pop()
+                    if mname == 'reverse':
+                        assert isinstance(obj, list)
+                        obj.reverse()
+                    else:
+                        raise NotImplementedError(
+                            'Unsupported (void) property %r on %r'
+                            % (mname, obj))
+                elif opcode == 86:  # newarray
+                    arg_count = u30()
+                    arr = []
+                    for i in range(arg_count):
+                        arr.append(stack.pop())
+                    arr = arr[::-1]
+                    stack.append(arr)
+                elif opcode == 93:  # findpropstrict
+                    index = u30()
+                    mname = self.multinames[index]
+                    for s in reversed(scopes):
+                        if mname in s:
+                            res = s
+                            break
+                    else:
+                        res = scopes[0]
+                    stack.append(res[mname])
+                elif opcode == 94:  # findproperty
+                    index = u30()
+                    mname = self.multinames[index]
+                    for s in reversed(scopes):
+                        if mname in s:
+                            res = s
+                            break
+                    else:
+                        res = avm_class.variables
+                    stack.append(res)
+                elif opcode == 96:  # getlex
+                    index = u30()
+                    mname = self.multinames[index]
+                    for s in reversed(scopes):
+                        if mname in s:
+                            scope = s
+                            break
+                    else:
+                        scope = avm_class.variables
+                    # I cannot find where static variables are initialized
+                    # so let's just return None
+                    res = scope.get(mname)
+                    stack.append(res)
+                elif opcode == 97:  # setproperty
+                    index = u30()
+                    value = stack.pop()
+                    idx = self.multinames[index]
+                    if isinstance(idx, _Multiname):
+                        idx = stack.pop()
+                    obj = stack.pop()
+                    obj[idx] = value
+                elif opcode == 98:  # getlocal
+                    index = u30()
+                    stack.append(registers[index])
+                elif opcode == 99:  # setlocal
+                    index = u30()
+                    value = stack.pop()
+                    registers[index] = value
+                elif opcode == 102:  # getproperty
+                    index = u30()
+                    pname = self.multinames[index]
+                    if pname == 'length':
+                        obj = stack.pop()
+                        assert isinstance(obj, list)
+                        stack.append(len(obj))
+                    else:  # Assume attribute access
+                        idx = stack.pop()
+                        assert isinstance(idx, int)
+                        obj = stack.pop()
+                        assert isinstance(obj, list)
+                        stack.append(obj[idx])
+                elif opcode == 115:  # convert_
+                    value = stack.pop()
+                    intvalue = int(value)
+                    stack.append(intvalue)
+                elif opcode == 128:  # coerce
+                    u30()
+                elif opcode == 133:  # coerce_s
+                    assert isinstance(stack[-1], (type(None), compat_str))
+                elif opcode == 160:  # add
+                    value2 = stack.pop()
+                    value1 = stack.pop()
+                    res = value1 + value2
+                    stack.append(res)
+                elif opcode == 161:  # subtract
+                    value2 = stack.pop()
+                    value1 = stack.pop()
+                    res = value1 - value2
+                    stack.append(res)
+                elif opcode == 164:  # modulo
+                    value2 = stack.pop()
+                    value1 = stack.pop()
+                    res = value1 % value2
+                    stack.append(res)
+                elif opcode == 175:  # greaterequals
+                    value2 = stack.pop()
+                    value1 = stack.pop()
+                    result = value1 >= value2
+                    stack.append(result)
+                elif opcode == 208:  # getlocal_0
+                    stack.append(registers[0])
+                elif opcode == 209:  # getlocal_1
+                    stack.append(registers[1])
+                elif opcode == 210:  # getlocal_2
+                    stack.append(registers[2])
+                elif opcode == 211:  # getlocal_3
+                    stack.append(registers[3])
+                elif opcode == 212:  # setlocal_0
+                    registers[0] = stack.pop()
+                elif opcode == 213:  # setlocal_1
+                    registers[1] = stack.pop()
+                elif opcode == 214:  # setlocal_2
+                    registers[2] = stack.pop()
+                elif opcode == 215:  # setlocal_3
+                    registers[3] = stack.pop()
+                else:
+                    raise NotImplementedError(
+                        'Unsupported opcode %d' % opcode)
+
+        avm_class.method_pyfunctions[func_name] = resfunc
+        return resfunc
+