Date: Sat, 8 Aug 2020 19:39:38 +0000 (UTC) From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364054 - head/sys/netinet Message-ID: <202008081939.078Jdciw056461@repo.freebsd.org>
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Author: tuexen Date: Sat Aug 8 19:39:38 2020 New Revision: 364054 URL: https://svnweb.freebsd.org/changeset/base/364054 Log: Improve the ECN negotiation when the TCP SYN-cache is used by making sure that * ECN is disabled if the client sends an non-ECN-setup SYN segment. * ECN is disabled is the ECN-setup SYN-ACK segment is retransmitted more than net.inet.tcp.ecn.maxretries times. Reviewed by: rscheff MFC after: 1 week Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D26008 Modified: head/sys/netinet/tcp_syncache.c Modified: head/sys/netinet/tcp_syncache.c ============================================================================== --- head/sys/netinet/tcp_syncache.c Sat Aug 8 16:56:20 2020 (r364053) +++ head/sys/netinet/tcp_syncache.c Sat Aug 8 19:39:38 2020 (r364054) @@ -510,6 +510,9 @@ syncache_timer(void *xsch) sch->sch_nextc = sc->sc_rxttime; continue; } + if (sc->sc_rxmits > V_tcp_ecn_maxretries) { + sc->sc_flags &= ~SCF_ECN; + } if (sc->sc_rxmits > V_tcp_syncache.rexmt_limit) { if ((s = tcp_log_addrs(&sc->sc_inc, NULL, NULL, NULL))) { log(LOG_DEBUG, "%s; %s: Retransmits exhausted, " @@ -1505,6 +1508,13 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *t sc->sc_tsreflect = to->to_tsval; else sc->sc_flags &= ~SCF_TIMESTAMP; + /* + * Disable ECN if needed. + */ + if ((sc->sc_flags & SCF_ECN) && + ((th->th_flags & (TH_ECE|TH_CWR)) != (TH_ECE|TH_CWR))) { + sc->sc_flags &= ~SCF_ECN; + } #ifdef MAC /* * Since we have already unconditionally allocated label
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