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网络编程通用结构体

文章目录
  1. 1. IPV4
  2. 2. IPV6
  3. 3. 通用结构体
    1. 3.0.1. sockaddr 16字节
    2. 3.0.2. sockaddr_storage 128字节

IPV4

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struct sockaddr_in {
       sa_family_t sin_family;             /* AF_INET */
       in_port_t sin_port;                 /* Port number.  */
       struct in_addr sin_addr;            /* Internet address.  */
  
       /* Pad to size of `struct sockaddr'.  */
       unsigned char sin_zero[sizeof (struct sockaddr) -
                              sizeof (sa_family_t) -
                              sizeof (in_port_t) -
                             sizeof (struct in_addr)];
};
typedef uint32_t in_addr_t;
struct in_addr  {
     in_addr_t s_addr;                    /* IPv4 address */
};

// 占据 16 个字节

IPV6

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struct sockaddr_in6 {
     sa_family_t sin6_family;    /* AF_INET6 */
     in_port_t sin6_port;        /* Transport layer port # */
     uint32_t sin6_flowinfo;     /* IPv6 flow information */
     struct in6_addr sin6_addr;  /* IPv6 address */
     uint32_t sin6_scope_id;     /* IPv6 scope-id */
 };
 struct in6_addr {
     union {
         uint8_t u6_addr8[16];
         uint16_t u6_addr16[8];
         uint32_t u6_addr32[4];
     } in6_u;
 
     #define s6_addr                 in6_u.u6_addr8
     #define s6_addr16               in6_u.u6_addr16
     #define s6_addr32               in6_u.u6_addr32
 };

通用结构体

sockaddr 16字节

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struct sockaddr { 
     sa_family_t sa_family;       /* Address family */
     char sa_data[14];            /* protocol-specific address */
};

sockaddr_storage 128字节

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  /* Structure large enough to hold any socket address 
  (with the historical exception of AF_UNIX). 128 bytes reserved.  */
  
  #if ULONG_MAX > 0xffffffff
  # define __ss_aligntype __uint64_t
  #else
  # define __ss_aligntype __uint32_t
  #endif
  #define _SS_SIZE        128
 #define _SS_PADSIZE     (_SS_SIZE - (2 * sizeof (__ss_aligntype)))
 
 struct sockaddr_storage
 {
     sa_family_t ss_family;      /* Address family */
     __ss_aligntype __ss_align;  /* Force desired alignment.  */
     char __ss_padding[_SS_PADSIZE];
};