tcp.h

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/*
 * tcp.h
 *
 * Transmission Control Protocol (RFC 793).
 *
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 *
 * $Id: tcp.h,v 1.17 2004/02/23 10:02:11 dugsong Exp $
 */

#ifndef DNET_TCP_H
#define DNET_TCP_H

#define TCP_HDR_LEN     20              /* base TCP header length */
#define TCP_OPT_LEN     2               /* base TCP option length */
#define TCP_OPT_LEN_MAX 40
#define TCP_HDR_LEN_MAX (TCP_HDR_LEN + TCP_OPT_LEN_MAX)

#ifndef __GNUC__
# define __attribute__(x)
# pragma pack(1)
#endif

/*
 * TCP header, without options
 */
struct tcp_hdr {
        uint16_t        th_sport;       /* source port */
        uint16_t        th_dport;       /* destination port */
        uint32_t        th_seq;         /* sequence number */
        uint32_t        th_ack;         /* acknowledgment number */
#if DNET_BYTESEX == DNET_BIG_ENDIAN
        uint8_t         th_off:4,       /* data offset */
                        th_x2:4;        /* (unused) */
#elif DNET_BYTESEX == DNET_LIL_ENDIAN
        uint8_t         th_x2:4,
                        th_off:4;
#else
# error "need to include <dnet.h>"
#endif
        uint8_t         th_flags;       /* control flags */
        uint16_t        th_win;         /* window */
        uint16_t        th_sum;         /* checksum */
        uint16_t        th_urp;         /* urgent pointer */
};

/*
 * TCP control flags (th_flags)
 */
#define TH_FIN          0x01            /* end of data */
#define TH_SYN          0x02            /* synchronize sequence numbers */
#define TH_RST          0x04            /* reset connection */
#define TH_PUSH         0x08            /* push */
#define TH_ACK          0x10            /* acknowledgment number set */
#define TH_URG          0x20            /* urgent pointer set */
#define TH_ECE          0x40            /* ECN echo, RFC 3168 */
#define TH_CWR          0x80            /* congestion window reduced */

#define TCP_PORT_MAX    65535           /* maximum port */
#define TCP_WIN_MAX     65535           /* maximum (unscaled) window */

/*
 * Sequence number comparison macros
 */
#define TCP_SEQ_LT(a,b)         ((int)((a)-(b)) < 0)
#define TCP_SEQ_LEQ(a,b)        ((int)((a)-(b)) <= 0)
#define TCP_SEQ_GT(a,b)         ((int)((a)-(b)) > 0)
#define TCP_SEQ_GEQ(a,b)        ((int)((a)-(b)) >= 0)

/*
 * TCP FSM states
 */
#define TCP_STATE_CLOSED        0       /* closed */
#define TCP_STATE_LISTEN        1       /* listening from connection */
#define TCP_STATE_SYN_SENT      2       /* active, have sent SYN */
#define TCP_STATE_SYN_RECEIVED  3       /* have sent and received SYN */

#define TCP_STATE_ESTABLISHED   4       /* established */
#define TCP_STATE_CLOSE_WAIT    5       /* rcvd FIN, waiting for close */

#define TCP_STATE_FIN_WAIT_1    6       /* have closed, sent FIN */
#define TCP_STATE_CLOSING       7       /* closed xchd FIN, await FIN-ACK */
#define TCP_STATE_LAST_ACK      8       /* had FIN and close, await FIN-ACK */

#define TCP_STATE_FIN_WAIT_2    9       /* have closed, FIN is acked */
#define TCP_STATE_TIME_WAIT     10      /* in 2*MSL quiet wait after close */
#define TCP_STATE_MAX           11

/*
 * Options (opt_type) - http://www.iana.org/assignments/tcp-parameters
 */
#define TCP_OPT_EOL             0       /* end of option list */
#define TCP_OPT_NOP             1       /* no operation */
#define TCP_OPT_MSS             2       /* maximum segment size */
#define TCP_OPT_WSCALE          3       /* window scale factor, RFC 1072 */
#define TCP_OPT_SACKOK          4       /* SACK permitted, RFC 2018 */
#define TCP_OPT_SACK            5       /* SACK, RFC 2018 */
#define TCP_OPT_ECHO            6       /* echo (obsolete), RFC 1072 */
#define TCP_OPT_ECHOREPLY       7       /* echo reply (obsolete), RFC 1072 */
#define TCP_OPT_TIMESTAMP       8       /* timestamp, RFC 1323 */
#define TCP_OPT_POCONN          9       /* partial order conn, RFC 1693 */
#define TCP_OPT_POSVC           10      /* partial order service, RFC 1693 */
#define TCP_OPT_CC              11      /* connection count, RFC 1644 */
#define TCP_OPT_CCNEW           12      /* CC.NEW, RFC 1644 */
#define TCP_OPT_CCECHO          13      /* CC.ECHO, RFC 1644 */
#define TCP_OPT_ALTSUM          14      /* alt checksum request, RFC 1146 */
#define TCP_OPT_ALTSUMDATA      15      /* alt checksum data, RFC 1146 */
#define TCP_OPT_SKEETER         16      /* Skeeter */
#define TCP_OPT_BUBBA           17      /* Bubba */
#define TCP_OPT_TRAILSUM        18      /* trailer checksum */
#define TCP_OPT_MD5             19      /* MD5 signature, RFC 2385 */
#define TCP_OPT_SCPS            20      /* SCPS capabilities */
#define TCP_OPT_SNACK           21      /* selective negative acks */
#define TCP_OPT_REC             22      /* record boundaries */
#define TCP_OPT_CORRUPT         23      /* corruption experienced */
#define TCP_OPT_SNAP            24      /* SNAP */
#define TCP_OPT_TCPCOMP         26      /* TCP compression filter */
#define TCP_OPT_MAX             27

#define TCP_OPT_TYPEONLY(type)  \
        ((type) == TCP_OPT_EOL || (type) == TCP_OPT_NOP)

/*
 * TCP option (following TCP header)
 */
struct tcp_opt {
        uint8_t         opt_type;       /* option type */
        uint8_t         opt_len;        /* option length >= TCP_OPT_LEN */
        union tcp_opt_data {
                uint16_t        mss;            /* TCP_OPT_MSS */
                uint8_t         wscale;         /* TCP_OPT_WSCALE */
                uint16_t        sack[19];       /* TCP_OPT_SACK */
                uint32_t        echo;           /* TCP_OPT_ECHO{REPLY} */
                uint32_t        timestamp[2];   /* TCP_OPT_TIMESTAMP */
                uint32_t        cc;             /* TCP_OPT_CC{NEW,ECHO} */
                uint8_t         cksum;          /* TCP_OPT_ALTSUM */
                uint8_t         md5[16];        /* TCP_OPT_MD5 */
                uint8_t         data8[TCP_OPT_LEN_MAX - TCP_OPT_LEN];
        } opt_data;
} __attribute__((__packed__));

#ifndef __GNUC__
# pragma pack()
#endif

#define tcp_pack_hdr(hdr, sport, dport, seq, ack, flags, win, urp) do { \
        struct tcp_hdr *tcp_pack_p = (struct tcp_hdr *)(hdr);           \
        tcp_pack_p->th_sport = htons(sport);                            \
        tcp_pack_p->th_dport = htons(dport);                            \
        tcp_pack_p->th_seq = htonl(seq);                                \
        tcp_pack_p->th_ack = htonl(ack);                                \
        tcp_pack_p->th_x2 = 0; tcp_pack_p->th_off = 5;                  \
        tcp_pack_p->th_flags = flags;                                   \
        tcp_pack_p->th_win = htons(win);                                \
        tcp_pack_p->th_urp = htons(urp);                                \
} while (0)

#endif /* DNET_TCP_H */

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