From owner-svn-src-all@freebsd.org Thu Nov 1 11:35:29 2018 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 66D4010ED7E6; Thu, 1 Nov 2018 11:35:29 +0000 (UTC) (envelope-from tuexen@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 155E1712BA; Thu, 1 Nov 2018 11:35:29 +0000 (UTC) (envelope-from tuexen@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id E066C1B23B; Thu, 1 Nov 2018 11:35:28 +0000 (UTC) (envelope-from tuexen@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id wA1BZSot094336; Thu, 1 Nov 2018 11:35:28 GMT (envelope-from tuexen@FreeBSD.org) Received: (from tuexen@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id wA1BZSAL094335; Thu, 1 Nov 2018 11:35:28 GMT (envelope-from tuexen@FreeBSD.org) Message-Id: <201811011135.wA1BZSAL094335@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: tuexen set sender to tuexen@FreeBSD.org using -f From: Michael Tuexen Date: Thu, 1 Nov 2018 11:35:28 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r339989 - head/sys/netinet X-SVN-Group: head X-SVN-Commit-Author: tuexen X-SVN-Commit-Paths: head/sys/netinet X-SVN-Commit-Revision: 339989 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Nov 2018 11:35:29 -0000 Author: tuexen Date: Thu Nov 1 11:35:28 2018 New Revision: 339989 URL: https://svnweb.freebsd.org/changeset/base/339989 Log: Improve a comment to refer to the actual sections in the TCP specification for the comparisons made. Thanks to lstewart@ for the suggestion. MFC after: 4 weeks Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D17595 Modified: head/sys/netinet/tcp_syncache.c Modified: head/sys/netinet/tcp_syncache.c ============================================================================== --- head/sys/netinet/tcp_syncache.c Thu Nov 1 10:25:22 2018 (r339988) +++ head/sys/netinet/tcp_syncache.c Thu Nov 1 11:35:28 2018 (r339989) @@ -581,15 +581,28 @@ syncache_chkrst(struct in_conninfo *inc, struct tcphdr /* * If the RST bit is set, check the sequence number to see * if this is a valid reset segment. + * * RFC 793 page 37: * In all states except SYN-SENT, all reset (RST) segments * are validated by checking their SEQ-fields. A reset is * valid if its sequence number is in the window. * - * The sequence number in the reset segment is normally an - * echo of our outgoing acknowlegement numbers, but some hosts - * send a reset with the sequence number at the rightmost edge - * of our receive window, and we have to handle this case. + * RFC 793 page 69: + * There are four cases for the acceptability test for an incoming + * segment: + * + * Segment Receive Test + * Length Window + * ------- ------- ------------------------------------------- + * 0 0 SEG.SEQ = RCV.NXT + * 0 >0 RCV.NXT =< SEG.SEQ < RCV.NXT+RCV.WND + * >0 0 not acceptable + * >0 >0 RCV.NXT =< SEG.SEQ < RCV.NXT+RCV.WND + * or RCV.NXT =< SEG.SEQ+SEG.LEN-1 < RCV.NXT+RCV.WND + * + * Note that when receiving a SYN segment in the LISTEN state, + * IRS is set to SEG.SEQ and RCV.NXT is set to SEG.SEQ+1, as + * described in RFC 793, page 66. */ if ((SEQ_GEQ(th->th_seq, sc->sc_irs + 1) && SEQ_LT(th->th_seq, sc->sc_irs + 1 + sc->sc_wnd)) || @@ -1731,6 +1744,7 @@ syncache_respond(struct syncache *sc, struct syncache_ th->th_seq = htonl(sc->sc_iss); else th->th_seq = htonl(sc->sc_iss + 1); +printf("SEG.SEQ=0x%x, ISS=0x%x.\n", ntohl(th->th_seq), sc->sc_iss); th->th_ack = htonl(sc->sc_irs + 1); th->th_off = sizeof(struct tcphdr) >> 2; th->th_x2 = 0;