Clean up delayed acks and T/TCP interactions:
- delay acks for T/TCP regardless of delack setting - fix bug where a single pass through tcp_input might not delay acks - use callout_active() instead of callout_pending() Sponsored by: DARPA, NAI Labs
This commit is contained in:
Jonathan Lemon
parent
ec20bdf897
commit
3bfd6421c2
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=111139
@ -153,14 +153,16 @@ do { \
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/*
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* Indicate whether this ack should be delayed. We can delay the ack if
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* - delayed acks are enabled and
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* - there is no delayed ack timer in progress and
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* - our last ack wasn't a 0-sized window. We never want to delay
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* the ack that opens up a 0-sized window.
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* the ack that opens up a 0-sized window and
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* - delayed acks are enabled or
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* - this is a half-synchronized T/TCP connection.
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*/
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#define DELAY_ACK(tp) \
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(tcp_delack_enabled && !callout_pending(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)
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#define DELAY_ACK(tp) \
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(((!callout_active(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)) && \
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(tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN)))
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static int
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tcp_reass(tp, th, tlenp, m)
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@ -505,7 +507,7 @@ tcp_input(m, off0)
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th->th_urp = ntohs(th->th_urp);
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/*
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* Delay droping TCP, IP headers, IPv6 ext headers, and TCP options,
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* Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
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* until after ip6_savecontrol() is called and before other functions
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* which don't want those proto headers.
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* Because ip6_savecontrol() is going to parse the mbuf to
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@ -862,23 +864,16 @@ tcp_input(m, off0)
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tp->t_state = TCPS_ESTABLISHED;
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/*
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* If there is a FIN, or if there is data and the
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* connection is local, then delay SYN,ACK(SYN) in
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* the hope of piggy-backing it on a response
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* segment. Otherwise must send ACK now in case
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* the other side is slow starting.
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* T/TCP logic:
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* If there is a FIN or if there is data, then
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* delay SYN,ACK(SYN) in the hope of piggy-backing
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* it on a response segment. Otherwise must send
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* ACK now in case the other side is slow starting.
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*/
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if (DELAY_ACK(tp) &&
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((thflags & TH_FIN) ||
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(tlen != 0 &&
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((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
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(!isipv6 && in_localaddr(inp->inp_faddr)))))) {
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_NEEDSYN;
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} else
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if (thflags & TH_FIN || tlen != 0)
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tp->t_flags |= (TF_DELACK | TF_NEEDSYN);
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else
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tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
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tcpstat.tcps_connects++;
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soisconnected(so);
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goto trimthenstep6;
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@ -1089,8 +1084,7 @@ tcp_input(m, off0)
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}
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sorwakeup(so);
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if (DELAY_ACK(tp)) {
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_DELACK;
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} else {
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tp->t_flags |= TF_ACKNOW;
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tcp_output(tp);
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@ -2099,8 +2093,7 @@ tcp_input(m, off0)
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LIST_EMPTY(&tp->t_segq) &&
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TCPS_HAVEESTABLISHED(tp->t_state)) {
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if (DELAY_ACK(tp))
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_DELACK;
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else
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tp->t_flags |= TF_ACKNOW;
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tp->rcv_nxt += tlen;
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@ -2143,9 +2136,8 @@ tcp_input(m, off0)
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* Otherwise, since we received a FIN then no
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* more input can be expected, send ACK now.
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*/
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if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN))
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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if (tp->t_flags & TF_NEEDSYN)
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tp->t_flags |= TF_DELACK;
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else
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tp->t_flags |= TF_ACKNOW;
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tp->rcv_nxt++;
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@ -2214,6 +2206,13 @@ tcp_input(m, off0)
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*/
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if (needoutput || (tp->t_flags & TF_ACKNOW))
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(void) tcp_output(tp);
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else if (tp->t_flags & TF_DELACK) {
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tp->t_flags &= ~TF_DELACK;
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KASSERT(!callout_active(tp->tt_delack),
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("delayed ack already active"));
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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}
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INP_UNLOCK(inp);
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return;
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@ -339,8 +339,9 @@ tcp_output(struct tcpcb *tp)
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* next expected input). If the difference is at least two
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* max size segments, or at least 50% of the maximum possible
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* window, then want to send a window update to peer.
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* Skip this if the connection is in T/TCP half-open state.
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*/
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if (win > 0) {
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if (win > 0 && !(tp->t_flags & TF_NEEDSYN)) {
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/*
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* "adv" is the amount we can increase the window,
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* taking into account that we are limited by
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@ -965,8 +966,8 @@ tcp_output(struct tcpcb *tp)
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if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
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tp->rcv_adv = tp->rcv_nxt + win;
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tp->last_ack_sent = tp->rcv_nxt;
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tp->t_flags &= ~TF_ACKNOW;
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if (tcp_delack_enabled)
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tp->t_flags &= ~(TF_ACKNOW | TF_DELACK);
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if (callout_active(tp->tt_delack))
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callout_stop(tp->tt_delack);
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#if 0
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/*
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@ -153,14 +153,16 @@ do { \
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/*
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* Indicate whether this ack should be delayed. We can delay the ack if
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* - delayed acks are enabled and
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* - there is no delayed ack timer in progress and
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* - our last ack wasn't a 0-sized window. We never want to delay
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* the ack that opens up a 0-sized window.
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* the ack that opens up a 0-sized window and
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* - delayed acks are enabled or
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* - this is a half-synchronized T/TCP connection.
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*/
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#define DELAY_ACK(tp) \
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(tcp_delack_enabled && !callout_pending(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)
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#define DELAY_ACK(tp) \
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(((!callout_active(tp->tt_delack) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0)) && \
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(tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN)))
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static int
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tcp_reass(tp, th, tlenp, m)
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@ -505,7 +507,7 @@ tcp_input(m, off0)
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th->th_urp = ntohs(th->th_urp);
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/*
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* Delay droping TCP, IP headers, IPv6 ext headers, and TCP options,
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* Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
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* until after ip6_savecontrol() is called and before other functions
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* which don't want those proto headers.
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* Because ip6_savecontrol() is going to parse the mbuf to
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@ -862,23 +864,16 @@ tcp_input(m, off0)
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tp->t_state = TCPS_ESTABLISHED;
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/*
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* If there is a FIN, or if there is data and the
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* connection is local, then delay SYN,ACK(SYN) in
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* the hope of piggy-backing it on a response
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* segment. Otherwise must send ACK now in case
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* the other side is slow starting.
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* T/TCP logic:
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* If there is a FIN or if there is data, then
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* delay SYN,ACK(SYN) in the hope of piggy-backing
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* it on a response segment. Otherwise must send
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* ACK now in case the other side is slow starting.
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*/
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if (DELAY_ACK(tp) &&
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((thflags & TH_FIN) ||
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(tlen != 0 &&
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((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
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(!isipv6 && in_localaddr(inp->inp_faddr)))))) {
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_NEEDSYN;
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} else
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if (thflags & TH_FIN || tlen != 0)
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tp->t_flags |= (TF_DELACK | TF_NEEDSYN);
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else
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tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
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tcpstat.tcps_connects++;
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soisconnected(so);
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goto trimthenstep6;
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@ -1089,8 +1084,7 @@ tcp_input(m, off0)
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}
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sorwakeup(so);
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if (DELAY_ACK(tp)) {
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_DELACK;
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} else {
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tp->t_flags |= TF_ACKNOW;
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tcp_output(tp);
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@ -2099,8 +2093,7 @@ tcp_input(m, off0)
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LIST_EMPTY(&tp->t_segq) &&
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TCPS_HAVEESTABLISHED(tp->t_state)) {
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if (DELAY_ACK(tp))
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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tp->t_flags |= TF_DELACK;
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else
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tp->t_flags |= TF_ACKNOW;
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tp->rcv_nxt += tlen;
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@ -2143,9 +2136,8 @@ tcp_input(m, off0)
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* Otherwise, since we received a FIN then no
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* more input can be expected, send ACK now.
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*/
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if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN))
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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if (tp->t_flags & TF_NEEDSYN)
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tp->t_flags |= TF_DELACK;
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else
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tp->t_flags |= TF_ACKNOW;
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tp->rcv_nxt++;
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@ -2214,6 +2206,13 @@ tcp_input(m, off0)
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*/
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if (needoutput || (tp->t_flags & TF_ACKNOW))
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(void) tcp_output(tp);
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else if (tp->t_flags & TF_DELACK) {
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tp->t_flags &= ~TF_DELACK;
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KASSERT(!callout_active(tp->tt_delack),
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("delayed ack already active"));
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callout_reset(tp->tt_delack, tcp_delacktime,
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tcp_timer_delack, tp);
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}
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INP_UNLOCK(inp);
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return;
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