socket的常用数据结构
IPv4 Socket Address Structure
netinet/in.h
struct in_addr {
in_addr_t s_addr; /* 32-bit IPv4 address normally uint32_t*/
/* network byte ordered */
};
struct sockaddr_in {
[uint8_t sin_len;] /* length of structure (16) */
sa_family_t sin_family; /* AF_INET if sin_len exit uint8_t,else unsigned short 16 bit integer*/
in_port_t sin_port; /* 16-bit TCP or UDP port number normally uint_16*/
/* network byte ordered */
struct in_addr sin_addr; /* 32-bit IPv4 address */
/* network byte ordered */
char sin_zero[8]; /* unused */
};//all socket address structures are at least 16 bytes in size
Generic Socket Address Structure
sys/socket.h
struct sockaddr {
[uint8_t sa_len;] /*similar as sockaddr_in*/
sa_family_t sa_family; /* address family: AF_xxx value */
char sa_data[14]; /* protocol-specific address */
};
IPv6 Socket Address Structure
netinet/in.h
struct in6_addr {
uint8_t s6_addr[16]; /* 128-bit IPv6 address */
/* network byte ordered */
};
#define SIN6_LEN /* required for compile-time tests */
struct sockaddr_in6 {
[uint8_t sin6_len;] /* length of this struct (28) controled by SIN6_LEN macro*/
sa_family_t sin6_family; /* AF_INET6 */
in_port_t sin6_port; /* transport layer port# */
/* network byte ordered */
uint32_t sin6_flowinfo; /* flow information, undefined */
struct in6_addr sin6_addr; /* IPv6 address */
/* network byte ordered */
uint32_t sin6_scope_id; /* set of interfaces for a scope */
};
New Generic Socket Address Structure
netinet/in.h
struct sockaddr_storage {
uint8_t ss_len; /* length of this struct (implementation dependent) */
sa_family_t ss_family; /* address family: AF_xxx value */
/* implementation-dependent elements to provide:
* a) alignment sufficient to fulfill the alignment requirements of
* all socket address types that the system supports.
* b) enough storage to hold any type of socket address that the
* system supports.
*/
};
连接过程
socket Function
#include <sys/socket.h>
int socket (int family, int type, int protocol);
/* Returns: non-negative descriptor if OK, -1 on error */