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tcp.h
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C/C++ Source or Header
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1994-07-11
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6KB
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168 lines
/* TCP implementation. Follows RFC 793 as closely as possible */
#define DEF_WND 2048 /* Default receiver window */
#define NTCB 19 /* # TCB hash table headers */
#define DEF_MSS 512 /* Default maximum segment size */
#define DEF_RTT 5000 /* Initial guess at round trip time (5 sec) */
#define MSL2 30 /* Guess at two maximum-segment lifetimes */
/* Round trip timing parameters */
#define AGAIN 8 /* Average RTT gain = 1/8 */
#define DGAIN 4 /* Mean deviation gain = 1/4 */
/* TCP segment header -- internal representation
* Note that this structure is NOT the actual header as it appears on the
* network (in particular, the offset and checksum fields are missing).
* All that knowledge is in the functions ntohtcp() and htontcp() in tcpsubr.c
*/
struct tcp {
int16 source; /* Source port */
int16 dest; /* Destination port */
int32 seq; /* Sequence number */
int32 ack; /* Acknowledgment number */
char flags; /* Flags, data offset */
#define URG 0x20 /* URGent flag */
#define ACK 0x10 /* ACKnowledgment flag */
#define PSH 0x08 /* PuSH flag */
#define RST 0x04 /* ReSeT flag */
#define SYN 0x02 /* SYNchronize flag */
#define FIN 0x01 /* FINal flag */
int16 wnd; /* Receiver flow control window */
int16 up; /* Urgent pointer */
int16 mss; /* Optional max seg size */
};
/* TCP options */
#define EOL_KIND 0
#define NOOP_KIND 1
#define MSS_KIND 2
#define TCPLEN 20
#define MSS_LENGTH 4
/* Resequencing queue entry */
struct reseq {
struct reseq *next; /* Linked-list pointer */
char tos; /* Type of service */
struct tcp seg; /* TCP header */
struct mbuf *bp; /* data */
int16 length; /* data length */
};
#define NULLRESEQ (struct reseq *)0
/* TCP connection control block */
struct tcb {
struct tcb *prev; /* Linked list pointers for hash table */
struct tcb *next;
struct connection conn;
char state; /* Connection state */
#define CLOSED 0 /* Must be 0 */
#define LISTEN 1
#define SYN_SENT 2
#define SYN_RECEIVED 3
#define ESTABLISHED 4
#define FINWAIT1 5
#define FINWAIT2 6
#define CLOSE_WAIT 7
#define CLOSING 8
#define LAST_ACK 9
#define TIME_WAIT 10
char reason; /* Reason for closing */
#define NORMAL 0 /* Normal close */
#define RESET 1 /* Reset by other end */
#define TIMEOUT 2 /* Excessive retransmissions */
#define NETWORK 3 /* Network problem (ICMP message) */
/* If reason == NETWORK, the ICMP type and code values are stored here */
char type;
char code;
/* Send sequence variables */
struct {
int32 una; /* First unacknowledged sequence number */
int32 nxt; /* Next sequence num to be sent for the first time */
int32 ptr; /* Working transmission pointer */
int16 wnd; /* Other end's offered receive window */
int16 up; /* Send urgent pointer */
int32 wl1; /* Sequence number used for last window update */
int32 wl2; /* Ack number used for last window update */
} snd;
int32 iss; /* Initial send sequence number */
int16 cwind; /* Congestion window */
int16 ssthresh; /* Slow-start threshold */
int32 resent; /* Count of bytes retransmitted */
/* Receive sequence variables */
struct {
int32 nxt; /* Incoming sequence number expected next */
int16 wnd; /* Our offered receive window */
int16 up; /* Receive urgent pointer */
} rcv;
int32 irs; /* Initial receive sequence number */
int16 mss; /* Maximum segment size */
int32 rerecv; /* Count of duplicate bytes received */
int16 window; /* Receiver window and send queue limit */
char backoff; /* Backoff interval */
void (*r_upcall)(); /* Call when "significant" amount of data arrives */
void (*t_upcall)(); /* Call when ok to send more data */
void (*s_upcall)(); /* Call when connection state changes */
char flags; /* Control flags */
#define FORCE 1 /* We owe the other end an ACK or window update */
#define CLONE 2 /* Server-type TCB, cloned on incoming SYN */
#define RETRAN 4 /* A retransmission has occurred */
#define ACTIVE 8 /* TCB created with an active open */
#define SYNACK 16 /* Our SYN has been acked */
char tos; /* Type of service (for IP) */
struct mbuf *rcvq; /* Receive queue */
int16 rcvcnt;
struct mbuf *sndq; /* Send queue */
int16 sndcnt; /* Number of unacknowledged sequence numbers on
* send queue. NB: includes SYN and FIN, which don't
* actually appear on sndq!
*/
struct reseq *reseq; /* Out-of-order segment queue */
struct timer timer; /* Retransmission timer */
struct timer rtt_timer; /* Round trip timer */
int32 rttseq; /* Sequence number being timed */
int32 srtt; /* Smoothed round trip time, milliseconds */
int32 mdev; /* Mean deviation, milliseconds */
char *user; /* User parameter (e.g., for mapping to an
* application control block
*/
};
#define NULLTCB (struct tcb *)0
/* TCP statistics counters */
struct tcp_stat {
int16 runt; /* Smaller than minimum size */
int16 checksum; /* TCP header checksum errors */
int16 conout; /* Outgoing connection attempts */
int16 conin; /* Incoming connection attempts */
int16 resets; /* Resets generated */
int16 bdcsts; /* Bogus broadcast packets */
};
extern struct tcp_stat tcp_stat;
extern struct tcb *tcbs[];
extern int32 iss();
struct tcb *lookup_tcb();
struct tcb *create_tcb();
void rehash_tcb(),tcp_output(),tcp_input(),close_self(),dump_seg(),
setstate();
struct mbuf *htontcp();
/* TCP primitives */
struct tcb *open_tcp();
int send_tcp(),recv_tcp(),close_tcp(),del_tcp();
void state_tcp(),tcp_dump();
extern int16 tcp_mss;
extern int16 tcp_window;
extern int32 tcp_irtt;