sockets - MASM:两次取消引用结构指针？

Question

我一直在使用 MASM 再次涉足 x86 程序集，但遇到了一个小障碍。希望从纯粹的享受中重新发明轮子。

    ASSUME eax:PTR hostent
    mov ebx, [eax].h_addr_list ;this doesn't compile -- but IDE recognizes hostent.h_addr_list
   ;I think I need to dereference the pointer twice, but I have no clue how to do that with MASM.
   ;It sounds silly, yes, but doing the traditional mov eax, [eax] won't solve my compiler error

    mov ecx, [eax].h_name ;this compiles just fine

   ;mov ebx, (hostent PTR [eax]).h_addr_list ;didn't work either.
   ASSUME eax:nothing 

问题似乎是 h_addr_list 是一个字符 **，而 h_name 是一个字符 *。抛出的错误是:

error A2006: undefined symbol : h_addr_list

hostent 结构的定义是:

    typedef struct hostent {
  char FAR      *h_name; //note the char FAR *
  char FAR  FAR **h_aliases;
  short         h_addrtype;
  short         h_length;
  char FAR  FAR **h_addr_list; //note the char FAR FAR **
} HOSTENT, *PHOSTENT, FAR *LPHOSTENT;

Answer 1

我强烈怀疑您正在使用 MASM32 并且有这样的一行:

include \masm32\include\windows.inc

windows.inc 包含 HOSTENT 结构:

hostent STRUCT
  h_name      DWORD      ?
  h_alias     DWORD      ?
  h_addr      WORD       ?
  h_len       WORD       ?
  h_list      DWORD      ?
hostent ENDS

比较一下:

typedef struct hostent {
  char FAR      *h_name; //note the char FAR *
  char FAR  FAR **h_aliases;
  short         h_addrtype;
  short         h_length;
  char FAR  FAR **h_addr_list; //note the char FAR FAR **
} HOSTENT, *PHOSTENT, FAR *LPHOSTENT;

你会注意到 h_addr_list在 windows.inc 中定义为 h_list .您可以修改 windows.inc 并重命名 h_list或者您可以修改您的代码以引用 h_list而不是 h_addr_list .我会做后者，因为它会使您的代码与其他使用 MASM32 的代码兼容。

还应该清楚的是，其他一些字段的命名也略有不同。