tcp.h

/* -*- c-basic-offset: 4 -*- */
#ifndef CLICKNET_TCP_H
#define CLICKNET_TCP_H
 
/*
 * <clicknet/tcp.h> -- TCP header definitions, based on one of the BSDs.
 *
 * Relevant RFCs include:
 *   RFC793     Transmission Control Protocol
 *   RFC1323    TCP Extensions for High Performance
 *   RFC2018    TCP Selective Acknowledgement Options
 *   RFC2581    TCP Congestion Control
 *   RFC2883    An Extension to the Selective Acknowledgement (SACK) Option
 *              for TCP
 *   RFC3168    The Addition of Explicit Congestion Notification (ECN) to IP
 *   RFC3540    Robust Explicit Congestion Notification (ECN) Signaling with
 *              Nonces
 * among many others.  See "A Roadmap for TCP Specification Documents",
 * currently an Internet-Draft.
 */
 
typedef uint32_t tcp_seq_t;
 
struct click_tcp {
    uint16_t    th_sport;               /* 0-1   source port                 */
    uint16_t    th_dport;               /* 2-3   destination port            */
    tcp_seq_t   th_seq;                 /* 4-7   sequence number             */
    tcp_seq_t   th_ack;                 /* 8-11  acknowledgement number      */
#if CLICK_BYTE_ORDER == CLICK_LITTLE_ENDIAN
    unsigned    th_flags2 : 4;          /* 12    more flags                  */
    unsigned    th_off : 4;             /*       data offset in words        */
#elif CLICK_BYTE_ORDER == CLICK_BIG_ENDIAN
    unsigned    th_off : 4;             /* 12    data offset in words        */
    unsigned    th_flags2 : 4;          /*       more flags                  */
#else
#   error "unknown byte order"
#endif
#define TH_NS           0x01            /*       in 'th_flags2'              */
    uint8_t     th_flags;               /* 13    flags                       */
#define TH_FIN          0x01
#define TH_SYN          0x02
#define TH_RST          0x04
#define TH_PUSH         0x08
#define TH_ACK          0x10
#define TH_URG          0x20
#define TH_ECE          0x40
#define TH_CWR          0x80
    uint16_t    th_win;                 /* 14-15 window                      */
    uint16_t    th_sum;                 /* 16-17 checksum                    */
    uint16_t    th_urp;                 /* 18-19 urgent pointer              */
};
 
/*
 * TCP sequence number comparisons
 */
 
#define SEQ_LT(x,y)     ((int)((x)-(y)) < 0)
#define SEQ_LEQ(x,y)    ((int)((x)-(y)) <= 0)
#define SEQ_GT(x,y)     ((int)((x)-(y)) > 0)
#define SEQ_GEQ(x,y)    ((int)((x)-(y)) >= 0)
 
/*
 * TCP options
 */
 
#define TCPOPT_EOL              0
#define TCPOPT_NOP              1
#define TCPOPT_MAXSEG           2
#define TCPOLEN_MAXSEG          4
#define TCPOPT_WSCALE           3
#define TCPOLEN_WSCALE          3
#define TCPOPT_SACK_PERMITTED   4
#define TCPOLEN_SACK_PERMITTED  2
#define TCPOPT_SACK             5
#define TCPOPT_TIMESTAMP        8
#define TCPOLEN_TIMESTAMP       10
 
struct tcp_opt_timestamp {
        uint32_t ts_val;
        uint32_t ts_ecr;
};
 
 
#endif