今晚遗留问题

1 为什么当host地址设置为INADDR_ANY以后，调用WSAIoctrl会出错。

2 如此定义IP头结构，struct的内存分配问题。

typedef struct ip_hdr
{
  unsigned char  ip_header_len:4;  // 4-bit header length (in 32-bit words)
  unsigned char  ip_version   :4;  // 4-bit IPv4 version
  unsigned char  ip_tos;           // IP type of service
  unsigned short ip_total_length;  // Total length
  unsigned short ip_id;            // Unique identifier 
  unsigned char  ip_frag_offset   :5; // Fragment offset field
  unsigned char  ip_more_fragment :1;
  unsigned char  ip_dont_fragment :1;
  unsigned char  ip_reserved_zero :1;
  unsigned char  ip_frag_offset1;    //fragment offset
  unsigned char  ip_ttl;           // Time to live
  unsigned char  ip_protocol;      // Protocol(TCP,UDP etc)
  unsigned short ip_checksum;      // IP checksum
  unsigned int   ip_srcaddr;       // Source address
  unsigned int   ip_destaddr;      // Source address
}   IPV4_HDR;