In a situation where:
- The remote host sends a FIN - in an ACK for a sequence number for which an ACK has already been received - There is still unacked data on route to the remote host - The packet does not contain a window update The packet may be dropped without processing the FIN flag. PR: kern/99188 Submitted by: Staffan Ulfberg <staffan@ulfberg.se> Discussed with: andre MFC after: never
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=258821
@ -2429,13 +2429,15 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
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hhook_run_tcp_est_in(tp, th, &to);
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if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
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if (tlen == 0 && tiwin == tp->snd_wnd) {
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if (tlen == 0 && tiwin == tp->snd_wnd &&
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!(thflags & TH_FIN)) {
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TCPSTAT_INC(tcps_rcvdupack);
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/*
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* If we have outstanding data (other than
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* a window probe), this is a completely
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* duplicate ack (ie, window info didn't
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* change), the ack is the biggest we've
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* change and FIN isn't set),
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* the ack is the biggest we've
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* seen and we've seen exactly our rexmt
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* threshhold of them, assume a packet
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* has been dropped and retransmit it.
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