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33 * @(#)tcp_seq.h 8.3 (Berkeley) 6/21/95
37 #ifndef _NETINET_TCP_SEQ_H_
38 #define _NETINET_TCP_SEQ_H_
40 * TCP sequence numbers are 32 bit integers operated
41 * on with modular arithmetic. These macros can be
42 * used to compare such integers.
44 #define SEQ_LT(a,b) ((int)((a)-(b)) < 0)
45 #define SEQ_LEQ(a,b) ((int)((a)-(b)) <= 0)
46 #define SEQ_GT(a,b) ((int)((a)-(b)) > 0)
47 #define SEQ_GEQ(a,b) ((int)((a)-(b)) >= 0)
49 /* for modulo comparisons of timestamps */
50 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
51 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
54 * TCP connection counts are 32 bit integers operated
55 * on with modular arithmetic. These macros can be
56 * used to compare such integers.
58 #define CC_LT(a,b) ((int)((a)-(b)) < 0)
59 #define CC_LEQ(a,b) ((int)((a)-(b)) <= 0)
60 #define CC_GT(a,b) ((int)((a)-(b)) > 0)
61 #define CC_GEQ(a,b) ((int)((a)-(b)) >= 0)
63 /* Macro to increment a CC: skip 0 which has a special meaning */
64 #define CC_INC(c) (++(c) == 0 ? ++(c) : (c))
67 * Macros to initialize tcp sequence numbers for
68 * send and receive from initial send and receive
71 #define tcp_rcvseqinit(tp) \
72 (tp)->rcv_adv = (tp)->rcv_nxt = (tp)->irs + 1
74 #define tcp_sendseqinit(tp) \
75 (tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = \
78 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * hz)
79 /* timestamp wrap-around time */
82 extern tcp_cc tcp_ccgen; /* global connection count */
85 * Increment for tcp_iss each second.
86 * This is designed to increment at the standard 250 KB/s,
87 * but with a random component averaging 128 KB.
88 * We also increment tcp_iss by a quarter of this amount
89 * each time we use the value for a new connection.
90 * If defined, the tcp_random18() macro should produce a
91 * number in the range [0-0x3ffff] that is hard to predict.
94 #define tcp_random18() ((random() >> 14) & 0x3ffff)
96 #define TCP_ISSINCR (122*1024 + tcp_random18())
98 extern tcp_seq tcp_iss; /* tcp initial send seq # */
100 #define TCP_ISSINCR (250*1024) /* increment for tcp_iss each second */
102 #endif /* _NETINET_TCP_SEQ_H_ */