Date: Wed, 1 Feb 2023 23:48:39 GMT From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: cd4974672ad3 - stable/13 - tcp: improve handling of SYN-ACK segments in TIMEWAIT state Message-ID: <202302012348.311NmdPL090949@gitrepo.freebsd.org>
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The branch stable/13 has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=cd4974672ad3204ebb27efb623f3aabfcc2b82ef commit cd4974672ad3204ebb27efb623f3aabfcc2b82ef Author: Michael Tuexen <tuexen@FreeBSD.org> AuthorDate: 2022-10-03 12:46:47 +0000 Commit: Michael Tuexen <tuexen@FreeBSD.org> CommitDate: 2023-02-01 23:47:53 +0000 tcp: improve handling of SYN-ACK segments in TIMEWAIT state Only consider segments with the SYN bit set and the ACK bit cleared as "new connection attempts", which result in re-using a connection being in TIMEWAIT state. This results in consistent handling of SYN-ACK segments. Reviewed by: rscheff@ Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D36864 (cherry picked from commit 2515552e6216095c3fa61d93ee024bb8861e07c2) --- sys/netinet/tcp_timewait.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c index f15cf6dae762..86c5e62fc9b6 100644 --- a/sys/netinet/tcp_timewait.c +++ b/sys/netinet/tcp_timewait.c @@ -456,7 +456,8 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, * are above the previous ones. * Allow UDP port number changes in this case. */ - if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { + if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && + SEQ_GT(th->th_seq, tw->rcv_nxt)) { tcp_twclose(tw, 0); TCPSTAT_INC(tcps_tw_recycles); return (1);
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