-
-/*
- * Structure to hold TCP options that are only used during segment
- * processing (in tcp_input), but not held in the tcpcb.
- * It's basically used to reduce the number of parameters
- * to tcp_dooptions.
- */
-struct tcpopt {
- u_long to_flag; /* which options are present */
-#define TOF_TS 0x0001 /* timestamp */
-#define TOF_CC 0x0002 /* CC and CCnew are exclusive */
-#define TOF_CCNEW 0x0004
-#define TOF_CCECHO 0x0008
- u_long to_tsval;
- u_long to_tsecr;
- tcp_cc to_cc; /* holds CC or CCnew */
- tcp_cc to_ccecho;
- u_short reserved; /* unused now: was to_maxseg */
-};
-
-/*
- * The TAO cache entry which is stored in the protocol family specific
- * portion of the route metrics.
- */
-struct rmxp_tao {
- tcp_cc tao_cc; /* latest CC in valid SYN */
- tcp_cc tao_ccsent; /* latest CC sent to peer */
- u_short tao_mssopt; /* peer's cached MSS */
-#ifdef notyet
- u_short tao_flags; /* cache status flags */
-#define TAOF_DONT 0x0001 /* peer doesn't understand rfc1644 */
-#define TAOF_OK 0x0002 /* peer does understand rfc1644 */
-#define TAOF_UNDEF 0 /* we don't know yet */
-#endif /* notyet */
-};
-#define rmx_taop(r) ((struct rmxp_tao *)(r).rmx_filler)
-
-#define intotcpcb(ip) ((struct tcpcb *)(ip)->inp_ppcb)
-#define sototcpcb(so) (intotcpcb(sotoinpcb(so)))
-
-/*
- * The smoothed round-trip time and estimated variance
- * are stored as fixed point numbers scaled by the values below.
- * For convenience, these scales are also used in smoothing the average
- * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
- * With these scales, srtt has 3 bits to the right of the binary point,
- * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
- * binary point, and is smoothed with an ALPHA of 0.75.
- */
-#define TCP_RTT_SCALE 32 /* multiplier for srtt; 3 bits frac. */
-#define TCP_RTT_SHIFT 5 /* shift for srtt; 3 bits frac. */
-#define TCP_RTTVAR_SCALE 16 /* multiplier for rttvar; 2 bits */
-#define TCP_RTTVAR_SHIFT 4 /* shift for rttvar; 2 bits */
-#define TCP_DELTA_SHIFT 2 /* see tcp_input.c */
-
-/*
- * The initial retransmission should happen at rtt + 4 * rttvar.
- * Because of the way we do the smoothing, srtt and rttvar
- * will each average +1/2 tick of bias. When we compute
- * the retransmit timer, we want 1/2 tick of rounding and
- * 1 extra tick because of +-1/2 tick uncertainty in the
- * firing of the timer. The bias will give us exactly the
- * 1.5 tick we need. But, because the bias is
- * statistical, we have to test that we don't drop below
- * the minimum feasible timer (which is 2 ticks).
- * This version of the macro adapted from a paper by Lawrence
- * Brakmo and Larry Peterson which outlines a problem caused
- * by insufficient precision in the original implementation,
- * which results in inappropriately large RTO values for very
- * fast networks.
- */
-#define TCP_REXMTVAL(tp) \
- max((tp)->t_rttmin, (((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)) \
- + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)
-#endif /* __APPLE_API_PRIVATE */
-
-#ifdef __APPLE_API_UNSTABLE
projects / apple / xnu.git / blobdiff