flash – 如何在AVM2字节码中找到方法？

发布时间：2020-12-15 07:25:41 所属栏目：百科来源：网络整理

导读：我一直在玩ABC字节码,并希望有人可以为我解决一个混乱点.我有一个简单的Flash文件,可以在舞台上放置一个剪辑,并有一个小脚本来更新它在每个帧上的位置.代码看起来像： package{ import flash.display.MovieClip; import flash.events.Event; public class Re

我一直在玩ABC字节码,并希望有人可以为我解决一个混乱点.我有一个简单的Flash文件,可以在舞台上放置一个剪辑,并有一个小脚本来更新它在每个帧上的位置.代码看起来像：

package
{
     import flash.display.MovieClip;     
     import flash.events.Event;

     public class RedCircle extends MovieClip
     {
          public function RedCircle()
          {
               this.addEventListener(Event.ENTER_FRAME,moveit);
          }

          function moveit(e:Event)
          {
               this.x -=1;
          }
     }
}

其编译类似于：

protected package protected RedCircle
{
    class RedCircle extends flash.display.MovieClip
    {
        static () : Void
        {
            getlocal_0();
            pushscope();
            returnvoid();
        }



        RedCircle () : Void
        {
            getlocal_0();
            pushscope();
            getlocal_0();
            constructsuper(0);
            getlocal_0();
            getlex(flash.events.Event);
            getproperty(ENTER_FRAME);
            getlex(internal .moveit);       // ###1
            callpropvoid(addEventListener,2);
            returnvoid();
        }



        function (anonymous) (flash.events.Event param1) : Void // ###2
        {
            getlocal_0();
            pushscope();
            getlocal_0();
            getlocal_0();
            getproperty(x);
            decrement();
            setproperty(x);
            returnvoid();
        }
    }
}

我的问题是’getlex’操作是如何工作的(我用### 1标记了它).它传递了一个引用该类的’moveit’方法的multiname.不幸的是,方法信息中的’name’字段似乎永远不会被编译器使用.所有方法都将空字符串作为其名称(在上面显示为### 2处的未命名函数).

Flash播放器如何将多个名称链接到未命名的方法？在AVM2规范中似乎没有这方面的规定.

我知道这是可能的,因为像sothink这样的商业反编译器会设法确定方法名称.我只是不确定他们是如何做到的,或者代码是如何工作的.

解决方法

我不确定为什么你的反编译器将该方法显示为(匿名).

这是abcData的转储：

abcFile{
minor_version (17): 16
major_version (19): 46
constant_pool{
    int_count (21): 0
        [0]: zero (not included in abcFile)
    uint_count (22): 0
        [0]: zero (not included in abcFile)
    double_count (23): 0
        [0]: NaN (not included in abcFile)
    string_count (24): 17
        string_info[0]{
            name: * (not included in abcFile)
        }
        string_info[1]{
            size (25): 12
            name (26): "flash.events"
        }
        string_info[2]{
            size (38): 5
            name (39): "Event"
        }
        string_info[3]{
            size (44): 0
            name (45): ""
        }
        string_info[4]{
            size (45): 9
            name (46): "RedCircle"
        }
        string_info[5]{
            size (55): 13
            name (56): "flash.display"
        }
        string_info[6]{
            size (69): 9
            name (70): "MovieClip"
        }
        string_info[7]{
            size (79): 6
            name (80): "moveit"
        }
        string_info[8]{
            size (86): 11
            name (87): "ENTER_FRAME"
        }
        string_info[9]{
            size (98): 16
            name (99): "addEventListener"
        }
        string_info[10]{
            size (115): 1
            name (116): "x"
        }
        string_info[11]{
            size (117): 6
            name (118): "Object"
        }
        string_info[12]{
            size (124): 15
            name (125): "EventDispatcher"
        }
        string_info[13]{
            size (140): 13
            name (141): "DisplayObject"
        }
        string_info[14]{
            size (154): 17
            name (155): "InteractiveObject"
        }
        string_info[15]{
            size (172): 22
            name (173): "DisplayObjectContainer"
        }
        string_info[16]{
            size (195): 6
            name (196): "Sprite"
        }
        namespace_count (202): 6
            namespace_info[0]{
                kind: * (not included in abcFile)
            }
            namespace_info[1]{
                kind (203): CONSTANT_PackageNamespace
                name (204): 1
            }
            namespace_info[2]{
                kind (205): CONSTANT_PackageNamespace
                name (206): 3
            }
            namespace_info[3]{
                kind (207): CONSTANT_PackageNamespace
                name (208): 5
            }
            namespace_info[4]{
                kind (209): CONSTANT_ProtectedNamespace
                name (210): 4
            }
            namespace_info[5]{
                kind (211): CONSTANT_PackageInternalNs
                name (212): 3
            }
        ns_set_count (213): 0
            ns_set_info[0]{
                ns: 0 (not included in abcFile)
            }
        multiname_count (214): 14
            multiname_info[0]{
                kind: 0 (not included in abcFile)
            }
            multiname_info[1]{
                kind (216): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (216): 1
                    name (217): 2 ("Event")
                }
            }
            multiname_info[2]{
                kind (219): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (219): 2
                    name (220): 4 ("RedCircle")
                }
            }
            multiname_info[3]{
                kind (222): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (222): 3
                    name (223): 6 ("MovieClip")
                }
            }
            multiname_info[4]{
                kind (225): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (225): 5
                    name (226): 7 ("moveit")
                }
            }
            multiname_info[5]{
                kind (228): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (228): 2
                    name (229): 8 ("ENTER_FRAME")
                }
            }
            multiname_info[6]{
                kind (231): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (231): 2
                    name (232): 9 ("addEventListener")
                }
            }
            multiname_info[7]{
                kind (234): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (234): 2
                    name (235): 10 ("x")
                }
            }
            multiname_info[8]{
                kind (237): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (237): 2
                    name (238): 11 ("Object")
                }
            }
            multiname_info[9]{
                kind (240): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (240): 1
                    name (241): 12 ("EventDispatcher")
                }
            }
            multiname_info[10]{
                kind (243): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (243): 3
                    name (244): 13 ("DisplayObject")
                }
            }
            multiname_info[11]{
                kind (246): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (246): 3
                    name (247): 14 ("InteractiveObject")
                }
            }
            multiname_info[12]{
                kind (249): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (249): 3
                    name (250): 15 ("DisplayObjectContainer")
                }
            }
            multiname_info[13]{
                kind (252): CONSTANT_QName
                multiname_kind_QNAME{
                    ns (252): 3
                    name (253): 16 ("Sprite")
                }
            }
    }
    method_count (254): 4
        method_info[0]{
            param_count (255): 0
            return_type (256): 0
            name (257): 0
            flags (258): 0
                NEED_ARGUMENTS (0x01): false
                NEED_ACTIVATION (0x02): false
                NEED_REST (0x04): false
                HAS_OPTIONAL (0x08): false
                SET_DXNS (0x40): false
                HAS_PARAM_NAMES (0x80): false
        }
        method_info[1]{
            param_count (259): 0
            return_type (260): 0
            name (261): 0
            flags (262): 0
                NEED_ARGUMENTS (0x01): false
                NEED_ACTIVATION (0x02): false
                NEED_REST (0x04): false
                HAS_OPTIONAL (0x08): false
                SET_DXNS (0x40): false
                HAS_PARAM_NAMES (0x80): false
        }
        method_info[2]{
            param_count (263): 1
            return_type (264): 0
            param_type[0] (265): 1
            name (266): 0
            flags (267): 0
                NEED_ARGUMENTS (0x01): false
                NEED_ACTIVATION (0x02): false
                NEED_REST (0x04): false
                HAS_OPTIONAL (0x08): false
                SET_DXNS (0x40): false
                HAS_PARAM_NAMES (0x80): false
        }
        method_info[3]{
            param_count (268): 0
            return_type (269): 0
            name (270): 0
            flags (271): 0
                NEED_ARGUMENTS (0x01): false
                NEED_ACTIVATION (0x02): false
                NEED_REST (0x04): false
                HAS_OPTIONAL (0x08): false
                SET_DXNS (0x40): false
                HAS_PARAM_NAMES (0x80): false
        }
    metadata_count (272): 0
    class_count (273): 1
        instance_info[0]{
            name (274): 2 (RedCircle)
            super_name (275): 3 (MovieClip)
            flags (276): 9
                CONSTANT_ClassSealed (0x01): true
                CONSTANT_ClassFinal (0x02): false
                CONSTANT_ClassInterface (0x04): false
                CONSTANT_ClassProtectedNs (0x08): true
            protectedNs (277): 4
            intrf_count (278): 0
            iinit (279): 1
            trait_count (280): 1
                traits_info[0]{
                    name (281): 4 (moveit)
                    kind (282): Trait_Method
                    ATTR_Final (0x1): false
                    ATTR_Override (0x2): false
                    ATTR_Metadata (0x4): false
                    trait_method{
                        disp_id (283): 0
                        method (284): 2
                    }
                }
        }
        class_info[0]{
            cinit (285): 0
            trait_count (286): 0
        }
    script_count (287): 1
        init (288): 3
            trait_count (289): 1
                traits_info[0]{
                    name (290): 2 (RedCircle)
                    kind (291): Trait_Class
                    ATTR_Metadata (0x4): false
                    trait_class{
                        slot_id (292): 1
                        classi (293): 0
                    }
                }
    method_body_count (294): 4
        method_body_info[0]{
            method (295): 0
            max_stack (296): 1
            local_count (297): 1
            init_scope_depth (298): 9
            max_scope_depth (299): 10
            code_length (300): 3
                208 0xD0 (301) getlocal_0
                48 0x30 (302) pushscope
                71 0x47 (303) returnvoid

            exception_count (304): 0
            trait_count (305): 0
        }
        method_body_info[1]{
            method (306): 1
            max_stack (307): 3
            local_count (308): 1
            init_scope_depth (309): 10
            max_scope_depth (310): 11
            code_length (311): 17
                208 0xD0 (312) getlocal_0
                48 0x30 (313) pushscope
                208 0xD0 (314) getlocal_0
                73 0x49 (315) constructsuper
                    arg_count: 0
                208 0xD0 (317) getlocal_0
                96 0x60 (318) getlex
                    index: 1 (Event)
                102 0x66 (320) getproperty
                    index: 5 (ENTER_FRAME)
                208 0xD0 (322) getlocal_0
                102 0x66 (323) getproperty
                    index: 4 (moveit)
                79 0x4F (325) callpropvoid
                    index: 6 (addEventListener)
                    arg_count: 2
                71 0x47 (328) returnvoid

            exception_count (329): 0
            trait_count (330): 0
        }
        method_body_info[2]{
            method (331): 2
            max_stack (332): 3
            local_count (333): 2
            init_scope_depth (334): 10
            max_scope_depth (335): 11
            code_length (336): 10
                208 0xD0 (337) getlocal_0
                48 0x30 (338) pushscope
                208 0xD0 (339) getlocal_0
                208 0xD0 (340) getlocal_0
                102 0x66 (341) getproperty
                    index: 7
                147 0x93 (343) decrement
                97 0x61 (344) setproperty
                    index: 7
                71 0x47 (346) returnvoid

            exception_count (347): 0
            trait_count (348): 0
        }
        method_body_info[3]{
            method (349): 3
            max_stack (350): 2
            local_count (351): 1
            init_scope_depth (352): 1
            max_scope_depth (353): 9
            code_length (354): 39
                208 0xD0 (355) getlocal_0
                48 0x30 (356) pushscope
                101 0x65 (357) getscopeobject
                    index: 0
                96 0x60 (359) getlex
                    index: 8
                48 0x30 (361) pushscope
                96 0x60 (362) getlex
                    index: 9
                48 0x30 (364) pushscope
                96 0x60 (365) getlex
                    index: 10
                48 0x30 (367) pushscope
                96 0x60 (368) getlex
                    index: 11
                48 0x30 (370) pushscope
                96 0x60 (371) getlex
                    index: 12
                48 0x30 (373) pushscope
                96 0x60 (374) getlex
                    index: 13
                48 0x30 (376) pushscope
                96 0x60 (377) getlex
                    index: 3
                48 0x30 (379) pushscope
                96 0x60 (380) getlex
                    index: 3
                88 0x58 (382) newclass
                    index: 0
                29 0x1D (384) popscope
                29 0x1D (385) popscope
                29 0x1D (386) popscope
                29 0x1D (387) popscope
                29 0x1D (388) popscope
                29 0x1D (389) popscope
                29 0x1D (390) popscope
                104 0x68 (391) initproperty
                    index: 2
                71 0x47 (393) returnvoid

            exception_count (394): 0
            trait_count (395): 0
        }
 }

你在这里感兴趣的是instance_info [0].这是类的运行时实例的定义,这里将是RedCircle.实例具有各种类型的特征数组. RedCircle有一种Trait_Method特征(moveit),这意味着特征引用了方法(2).

因此,如果跳到method_body_info [1](RedCircle的构造函数),您可以在字节323看到调用getProperty时索引为4.

102 0x66 (323) getproperty
                   index: 4 (moveit)

这是对多个名称常量池的引用.

multiname_info[4]{
    kind (225): CONSTANT_QName
    multiname_kind_QNAME{
        ns (225): 5
        name (226): 7 ("moveit")
    }
}

在调用方法时,它会在实例的特征中查找名称索引.

traits_info[0]{
    name (281): 4 (moveit)
    kind (282): Trait_Method
    ATTR_Final (0x1): false
    ATTR_Override (0x2): false
    ATTR_Metadata (0x4): false
    trait_method{
        disp_id (283): 0
        method (284): 2
    }
}

然后调用相关方法.

method_info[2]{
    param_count (263): 1
    return_type (264): 0
    param_type[0] (265): 1
    name (266): 0
    flags (267): 0
        NEED_ARGUMENTS (0x01): false
        NEED_ACTIVATION (0x02): false
        NEED_REST (0x04): false
        HAS_OPTIONAL (0x08): false
        SET_DXNS (0x40): false
        HAS_PARAM_NAMES (0x80): false
}

method_body_info[2]{
    method (331): 2
    max_stack (332): 3
    local_count (333): 2
    init_scope_depth (334): 10
    max_scope_depth (335): 11
    code_length (336): 10
        208 0xD0 (337) getlocal_0
        48 0x30 (338) pushscope
        208 0xD0 (339) getlocal_0
        208 0xD0 (340) getlocal_0
        102 0x66 (341) getproperty
                           index: 7 (x)
        147 0x93 (343) decrement
        97 0x61 (344) setproperty
                           index: 7 (x)
        71 0x47 (346) returnvoid
    exception_count (347): 0
    trait_count (348): 0
}

一个简化的答案,但我希望它能解决一些问题.

（编辑：李大同）

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