Author: tuexen Date: Tue Dec 4 22:46:58 2018 New Revision: 341504 URL: https://svnweb.freebsd.org/changeset/base/341504
Log: MFC r339989, r339991: Improve a comment to refer to the actual sections in the TCP specification for the comparisons made. Thanks to lstewart@ for the suggestion. Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D17595 Modified: stable/12/sys/netinet/tcp_syncache.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/netinet/tcp_syncache.c ============================================================================== --- stable/12/sys/netinet/tcp_syncache.c Tue Dec 4 22:25:24 2018 (r341503) +++ stable/12/sys/netinet/tcp_syncache.c Tue Dec 4 22:46:58 2018 (r341504) @@ -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)) || _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
