diff options
Diffstat (limited to 'sys/netinet')
| -rw-r--r-- | sys/netinet/tcp_input.c | 63 |
1 files changed, 47 insertions, 16 deletions
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 22caaf6..0e3308b 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -1714,7 +1714,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, * Pull snd_wl1 up to prevent seq wrap relative to * th_seq. */ - tp->snd_wl1 = th->th_seq; + tp->snd_wl1 = th->th_seq + tlen; /* * Pull rcv_up up to prevent seq wrap relative to * rcv_nxt. @@ -2327,7 +2327,6 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, if (tlen == 0 && (thflags & TH_FIN) == 0) (void) tcp_reass(tp, (struct tcphdr *)0, 0, (struct mbuf *)0); - tp->snd_wl1 = th->th_seq - 1; /* FALLTHROUGH */ /* @@ -2638,12 +2637,10 @@ process_ACK: SOCKBUF_LOCK(&so->so_snd); if (acked > so->so_snd.sb_cc) { - tp->snd_wnd -= so->so_snd.sb_cc; sbdrop_locked(&so->so_snd, (int)so->so_snd.sb_cc); ourfinisacked = 1; } else { sbdrop_locked(&so->so_snd, acked); - tp->snd_wnd -= acked; ourfinisacked = 0; } /* NB: sowwakeup_locked() does an implicit unlock. */ @@ -2733,24 +2730,56 @@ step6: INP_WLOCK_ASSERT(tp->t_inpcb); /* - * Update window information. - * Don't look at window if no ACK: TAC's send garbage on first SYN. + * Window update acceptance logic. We have to be careful not + * to accept window updates from old segments in the presence + * of reordering or duplication. + * + * A window update is valid when: + * - the segment ACK's new data. + * - the segment carries new data and its ACK is current. + * - the segment matches the current SEQ and ACK but increases + * the window. This is the escape from persist mode, if there + * data to be sent. + * + * XXXAO: The presence of new SACK information would allow to + * accept window updates during retransmits. We don't have an + * easy way to test for that the moment. + * + * NB: The other side isn't allowed to shrink the window when + * not sending or acking new data. This behavior is strongly + * discouraged by RFC793, section 3.7, page 42 anyways. + * + * XXXAO: tiwin >= minmss to avoid jitter? */ - if ((thflags & TH_ACK) && - (SEQ_LT(tp->snd_wl1, th->th_seq) || - (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || - (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { - /* keep track of pure window updates */ - if (tlen == 0 && - tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) + if ((thflags & TH_ACK) && tiwin != tp->snd_wnd && + (SEQ_GT(th->th_ack, tp->snd_wl2) || + (th->th_ack == tp->snd_wl2 && + (SEQ_GT(th->th_seq + tlen, tp->snd_wl1) || + (th->th_seq == tp->snd_wl1 && tlen == 0 && tiwin > tp->snd_wnd))))) { +#if 0 + char *s; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { + log(LOG_DEBUG, "%s; %s: window update %lu -> %lu\n", + s, __func__, tp->snd_wnd, tiwin); + free(s, M_TCPLOG); + } +#endif + /* Keep track of pure window updates. */ + if (th->th_seq == tp->snd_wl1 && tlen == 0 && + tiwin > tp->snd_wnd) TCPSTAT_INC(tcps_rcvwinupd); + /* + * When the new window is larger, nudge output + * as we may be able to send more data. + */ + if (tiwin > tp->snd_wnd) + needoutput = 1; tp->snd_wnd = tiwin; - tp->snd_wl1 = th->th_seq; - tp->snd_wl2 = th->th_ack; if (tp->snd_wnd > tp->max_sndwnd) tp->max_sndwnd = tp->snd_wnd; - needoutput = 1; } + if (SEQ_GT(th->th_ack, tp->snd_wl2)) + tp->snd_wl2 = th->th_ack; /* * Process segments with URG. @@ -2870,6 +2899,8 @@ dodata: /* XXX */ thflags = tcp_reass(tp, th, &tlen, m); tp->t_flags |= TF_ACKNOW; } + if (SEQ_GT(th->th_seq, tp->snd_wl1)) + tp->snd_wl1 = th->th_seq + tlen; if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT)) tcp_update_sack_list(tp, save_start, save_start + tlen); #if 0 |
