网络协议 第1篇: TCP & UDP

写道

DOD STANDARD TRANSMISSION CONTROL PROTOCOL
https://www.iteye.com/blog/lobin-2328266

 

 

1、TCP

 

 

网络地址

 

网络地址结构定义如下：

/* Internet address. */

struct in_addr

{

  in_addr_t s_addr;

};

 

对于ipv4来说，网络地址是一个32位的地址，所以in_addr_t被定义为一个32位的无符号整型类型。

typedef uint32_t in_addr_t;

ip地址（点分格式）转换为32位的地址（in_addr_t）参考另一篇文章：https://www.iteye.com/blog/lobin-2511945

 

 

socket地址

socket地址包括协议簇、端口、网络地址信息。socket地址存在多种定义。

 

socket地址结构定义如下：

/* Structure describing an Internet (IP) socket address. */

#define __SOCK_SIZE__16/* sizeof(struct sockaddr)*/

struct sockaddr_in

{

  sa_family_t sin_family;/* Address family*/

  in_port_t sin_port;/* Port number*/

  struct in_addr sin_addr;/* Internet address*/

 

  /* Pad to size of `struct sockaddr'. */

  unsigned char  __pad[__SOCK_SIZE__ - sizeof(short int)

- sizeof(unsigned short int) - sizeof(struct in_addr)];

};

#define sin_zero__pad/* for BSD UNIX comp. -FvK*/

 

 

 

struct sockaddr {

  sa_family_tsa_family;/* address family, AF_xxx*/

  charsa_data[14];/* 14 bytes of protocol address*/

};

 

 

/* POSIX requires only at least 100 bytes */

#define UNIX_PATH_MAX   108

 

struct sockaddr_un {

  sa_family_t sun_family;              /* address family AF_LOCAL/AF_UNIX */

  char         sun_path[UNIX_PATH_MAX]; /* 108 bytes of socket address     */

};

 

协议簇被定义为一个16位的无符号整型类型。

typedef uint16_t sa_family_t;

 

/* Supported address families. */

/*

 * Address families.

 */

#define AF_UNSPEC       0               /* unspecified */

#define AF_UNIX         1               /* local to host (pipes, portals) */

#define AF_LOCAL        1               /* POSIX name for AF_UNIX */

#define AF_INET         2               /* internetwork: UDP, TCP, etc. */

#define AF_IMPLINK      3               /* arpanet imp addresses */

#define AF_PUP          4               /* pup protocols: e.g. BSP */

#define AF_CHAOS        5               /* mit CHAOS protocols */

#define AF_NS           6               /* XEROX NS protocols */

#define AF_ISO          7               /* ISO protocols */

#define AF_OSI          AF_ISO          /* OSI is ISO */

#define AF_ECMA         8               /* european computer manufacturers */

#define AF_DATAKIT      9               /* datakit protocols */

#define AF_CCITT        10              /* CCITT protocols, X.25 etc */

#define AF_SNA          11              /* IBM SNA */

#define AF_DECnet       12              /* DECnet */

#define AF_DLI          13              /* Direct data link interface */

#define AF_LAT          14              /* LAT */

#define AF_HYLINK       15              /* NSC Hyperchannel */

#define AF_APPLETALK    16              /* AppleTalk */

#define AF_NETBIOS      17              /* NetBios-style addresses */

#define AF_INET6        23              /* IP version 6 */

 

#define AF_MAX          32

/*

 * Protocol families, same as address families for now.

 */

#define PF_UNSPEC       AF_UNSPEC

#define PF_UNIX         AF_UNIX

#define PF_LOCAL        AF_LOCAL

#define PF_INET         AF_INET

#define PF_IMPLINK      AF_IMPLINK

#define PF_PUP          AF_PUP

#define PF_CHAOS        AF_CHAOS

#define PF_NS           AF_NS

#define PF_ISO          AF_ISO

#define PF_OSI          AF_OSI

#define PF_ECMA         AF_ECMA

#define PF_DATAKIT      AF_DATAKIT

#define PF_CCITT        AF_CCITT

#define PF_SNA          AF_SNA

#define PF_DECnet       AF_DECnet

#define PF_DLI          AF_DLI

#define PF_LAT          AF_LAT

#define PF_HYLINK       AF_HYLINK

#define PF_APPLETALK    AF_APPLETALK

#define PF_NETBIOS      AF_NETBIOS

#define PF_INET6        AF_INET6

 

#define PF_MAX          AF_MAX

协议簇被定义成和地址簇一样。

 

 

 

#define TCPCB_FLAG_FIN0x01

#define TCPCB_FLAG_SYN0x02

#define TCPCB_FLAG_RST0x04

#define TCPCB_FLAG_PSH0x08

#define TCPCB_FLAG_ACK0x10

#define TCPCB_FLAG_URG0x20

#define TCPCB_FLAG_ECE0x40

#define TCPCB_FLAG_CWR0x80

 

URG控制位：

带外（out-of-band）数据

 

ACK控制位

 

PSH控制位

 

RST控制位

 

SYN控制位

 

FIN控制位

 

 

状态：

enum {

  TCP_ESTABLISHED = 1,

  TCP_SYN_SENT,

  TCP_SYN_RECV,

  TCP_FIN_WAIT1,

  TCP_FIN_WAIT2,

  TCP_TIME_WAIT,

  TCP_CLOSE,

  TCP_CLOSE_WAIT,

  TCP_LAST_ACK,

  TCP_LISTEN,

  TCP_CLOSING, /* now a valid state */

 

  TCP_MAX_STATES /* Leave at the end! */

};

 

1、TCP_SYN_SENT

2、TCP_ESTABLISHED

3、TCP_CLOSE_WAIT

4、TCP_CLOSE

 

 

enum {

  TCPF_ESTABLISHED = (1 << 1),

  TCPF_SYN_SENT  = (1 << 2),

  TCPF_SYN_RECV  = (1 << 3),

  TCPF_FIN_WAIT1 = (1 << 4),

  TCPF_FIN_WAIT2 = (1 << 5),

  TCPF_TIME_WAIT = (1 << 6),

  TCPF_CLOSE     = (1 << 7),

  TCPF_CLOSE_WAIT = (1 << 8),

  TCPF_LAST_ACK  = (1 << 9),

  TCPF_LISTEN    = (1 << 10),

  TCPF_CLOSING   = (1 << 11) 

};

 

 

2、UDP