linux 網絡編程常用結構體

在/usr/include/linux/socket.h中定義

struct sockaddr {
        sa_family_t     sa_family;    /* address family, AF_xxx       */
        char            sa_data[14];    /* 14 bytes of protocol address */

}；

在/usr/include/netinet/in.h中定義

struct sockaddr_in

{
    __SOCKADDR_COMMON (sin_);
    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) -
                           __SOCKADDR_COMMON_SIZE -
                           sizeof (in_port_t) -
                           sizeof (struct in_addr)];    
                           /* 字符數組sin_zero[8]的存在是爲了保證結構體struct sockaddr_in的大小和結構體struct sockaddr的大小相等 */

};

struct sockaddr_in6 {
        short   sin6_family;
        u_short sin6_port;
        u_long  sin6_flowinfo;
        struct  in6_addr sin6_addr;
        u_long  sin6_scope_id;
};

struct in6_addr {
union {
__u8 u6_addr8[16];
__be16 u6_addr16[8];
__be32 u6_addr32[4];
} in6_u;

struct in_addr {
        unsigned long s_addr;
};

struct sockaddr_nl {
sa_family_t nl_family; /*AF_NETLINK*/
unsigned short nl_pad; /* 0 */
pid_t nl_pid; /* 進程pid */
u_32 nl_groups; /* 多播組掩碼*/
}nl;

struct nlmsghdr {
_u32 nlmsg_len; /* Length of msg including header */
_u32 nlmsg_type; /* 操作命令 */
_u16 nlmsg_flags; /* various flags */
_u32 nlmsg_seq; /* Sequence number */
_u32 nlmsg_pid; /* 進程PID */
};

struct rtmsg {
unsigned char rtm_family; /* 路由表地址族 */
unsigned char rtm_dst_len; /* 目的長度 */
unsigned char rtm_src_len; /* 源長度 */ (2.4.10頭文件的註釋標反了？)
unsigned char rtm_tos; /* TOS */

unsigned char rtm_table; /* 路由表選取 */
unsigned char rtm_protocol; /* 路由協議 */
unsigned char rtm_scope;
unsigned char rtm_type;

unsigned int rtm_flags;
};

  struct addrinfo {
               int              ai_flags;
               int              ai_family;//AF_INET,AF_INET6或者AF_UNSPEC
               int              ai_socktype;//SOCK_STREAM or SOCK_DGRAM
               int              ai_protocol;//0
               size_t           ai_addrlen;//往下參數在hints中均爲0或NULL
               struct sockaddr *ai_addr;
               char            *ai_canonname;
               struct addrinfo *ai_next;
           };