317 lines
10 KiB
C
317 lines
10 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
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*/
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#include "../tcplp.h"
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#include "../lib/bitmap.h"
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#include "../lib/cbuf.h"
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#include "tcp.h"
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#include "tcp_fsm.h"
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#include "tcp_seq.h"
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#include "tcp_var.h"
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/*
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* samkumar: Segments are only reassembled within the window; data outside the
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* window is thrown away. So, the total amount of reassembly data cannot exceed
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* the size of the receive window.
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*
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* I have essentially rewritten it to use TCPlp's data structure for the
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* reassembly buffer. I have kept the original code as a comment below this
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* function, for reference.
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*
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* Looking at the usage of this function in tcp_input, this just has to set
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* *tlenp to 0 if the received segment is already completely buffered; it does
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* not need to update it if only part of the segment is trimmed off.
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*/
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int
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tcp_reass(struct tcpcb* tp, struct tcphdr* th, int* tlenp, otMessage* data, off_t data_offset, struct tcplp_signals* sig)
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{
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size_t mergeable, written;
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size_t offset;
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size_t start_index;
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size_t usedbefore;
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int tlen;
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size_t merged = 0;
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int flags = 0;
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/*
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* Call with th==NULL after become established to
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* force pre-ESTABLISHED data up to user socket.
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*/
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if (th == NULL)
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goto present;
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tlen = *tlenp;
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/* Insert the new segment queue entry into place. */
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KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), ("Adding past segment to the reassembly queue"));
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offset = (size_t) (th->th_seq - tp->rcv_nxt);
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if (cbuf_reass_count_set(&tp->recvbuf, (size_t) offset, tp->reassbmp, tlen) >= (size_t) tlen) {
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*tlenp = 0;
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goto present;
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}
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written = cbuf_reass_write(&tp->recvbuf, (size_t) offset, data, data_offset, tlen, tp->reassbmp, &start_index, cbuf_copy_from_message);
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if ((th->th_flags & TH_FIN) && (tp->reass_fin_index == -1)) {
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tp->reass_fin_index = (int16_t) (start_index + tlen);
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}
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KASSERT(written == tlen, ("Reassembly write out of bounds: tried to write %d, but wrote %d", tlen, (int) written));
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present:
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/*
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* Present data to user, advancing rcv_nxt through
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* completed sequence space.
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*/
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mergeable = cbuf_reass_count_set(&tp->recvbuf, 0, tp->reassbmp, (size_t) 0xFFFFFFFF);
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usedbefore = cbuf_used_space(&tp->recvbuf);
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if (!tpiscantrcv(tp) || usedbefore == 0) {
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/* If usedbefore == 0, but we can't receive more, then we still need to move the buffer
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along by merging and then popping, in case we receive a FIN later on. */
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if (tp->reass_fin_index >= 0 && cbuf_reass_within_offset(&tp->recvbuf, mergeable, (size_t) tp->reass_fin_index)) {
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tp->reass_fin_index = -2; // So we won't consider any more FINs
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flags = TH_FIN;
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}
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merged = cbuf_reass_merge(&tp->recvbuf, mergeable, tp->reassbmp);
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KASSERT(merged == mergeable, ("Reassembly merge out of bounds: tried to merge %d, but merged %d", (int) mergeable, (int) merged));
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if (tpiscantrcv(tp)) {
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cbuf_pop(&tp->recvbuf, merged); // So no data really enters the buffer
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} else if (merged > 0) {
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sig->recvbuf_added = true;
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}
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} else {
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/* If there is data in the buffer AND we can't receive more, then that must be because we received a FIN,
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but the user hasn't yet emptied the buffer of its contents. */
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KASSERT (tp->reass_fin_index == -2, ("Can't receive more, and data in buffer, but haven't received a FIN"));
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}
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tp->rcv_nxt += mergeable;
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return flags;
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}
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#if 0
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int
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tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
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{
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struct tseg_qent *q;
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struct tseg_qent *p = NULL;
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struct tseg_qent *nq;
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struct tseg_qent *te = NULL;
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struct socket *so = tp->t_inpcb->inp_socket;
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char *s = NULL;
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int flags;
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struct tseg_qent tqs;
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INP_WLOCK_ASSERT(tp->t_inpcb);
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/*
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* XXX: tcp_reass() is rather inefficient with its data structures
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* and should be rewritten (see NetBSD for optimizations).
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*/
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/*
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* Call with th==NULL after become established to
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* force pre-ESTABLISHED data up to user socket.
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*/
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if (th == NULL)
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goto present;
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/*
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* Limit the number of segments that can be queued to reduce the
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* potential for mbuf exhaustion. For best performance, we want to be
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* able to queue a full window's worth of segments. The size of the
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* socket receive buffer determines our advertised window and grows
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* automatically when socket buffer autotuning is enabled. Use it as the
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* basis for our queue limit.
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* Always let the missing segment through which caused this queue.
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* NB: Access to the socket buffer is left intentionally unlocked as we
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* can tolerate stale information here.
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*
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* XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
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* should work but causes packets to be dropped when they shouldn't.
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* Investigate why and re-evaluate the below limit after the behaviour
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* is understood.
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*/
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if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
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tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) {
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TCPSTAT_INC(tcps_rcvreassfull);
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*tlenp = 0;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
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log(LOG_DEBUG, "%s; %s: queue limit reached, "
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"segment dropped\n", s, __func__);
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free(s, M_TCPLOG);
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}
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m_freem(m);
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return (0);
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}
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/*
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* Allocate a new queue entry. If we can't, or hit the zone limit
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* just drop the pkt.
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*
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* Use a temporary structure on the stack for the missing segment
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* when the zone is exhausted. Otherwise we may get stuck.
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*/
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te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
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if (te == NULL) {
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if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) {
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TCPSTAT_INC(tcps_rcvmemdrop);
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m_freem(m);
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*tlenp = 0;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
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NULL))) {
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log(LOG_DEBUG, "%s; %s: global zone limit "
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"reached, segment dropped\n", s, __func__);
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free(s, M_TCPLOG);
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}
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return (0);
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} else {
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bzero(&tqs, sizeof(struct tseg_qent));
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te = &tqs;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
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NULL))) {
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log(LOG_DEBUG,
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"%s; %s: global zone limit reached, using "
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"stack for missing segment\n", s, __func__);
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free(s, M_TCPLOG);
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}
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}
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}
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tp->t_segqlen++;
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/*
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* Find a segment which begins after this one does.
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*/
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LIST_FOREACH(q, &tp->t_segq, tqe_q) {
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if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
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break;
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p = q;
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}
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/*
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* If there is a preceding segment, it may provide some of
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* our data already. If so, drop the data from the incoming
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* segment. If it provides all of our data, drop us.
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*/
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if (p != NULL) {
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int i;
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/* conversion to int (in i) handles seq wraparound */
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i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
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if (i > 0) {
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if (i >= *tlenp) {
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TCPSTAT_INC(tcps_rcvduppack);
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TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
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m_freem(m);
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if (te != &tqs)
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uma_zfree(tcp_reass_zone, te);
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tp->t_segqlen--;
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/*
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* Try to present any queued data
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* at the left window edge to the user.
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* This is needed after the 3-WHS
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* completes.
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*/
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goto present; /* ??? */
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}
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m_adj(m, i);
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*tlenp -= i;
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th->th_seq += i;
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}
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}
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tp->t_rcvoopack++;
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TCPSTAT_INC(tcps_rcvoopack);
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TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
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/*
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* While we overlap succeeding segments trim them or,
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* if they are completely covered, dequeue them.
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*/
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while (q) {
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int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
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if (i <= 0)
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break;
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if (i < q->tqe_len) {
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q->tqe_th->th_seq += i;
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q->tqe_len -= i;
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m_adj(q->tqe_m, i);
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break;
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}
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nq = LIST_NEXT(q, tqe_q);
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LIST_REMOVE(q, tqe_q);
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m_freem(q->tqe_m);
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uma_zfree(tcp_reass_zone, q);
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tp->t_segqlen--;
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q = nq;
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}
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/* Insert the new segment queue entry into place. */
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te->tqe_m = m;
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te->tqe_th = th;
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te->tqe_len = *tlenp;
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if (p == NULL) {
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LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
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} else {
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KASSERT(te != &tqs, ("%s: temporary stack based entry not "
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"first element in queue", __func__));
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LIST_INSERT_AFTER(p, te, tqe_q);
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}
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present:
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/*
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* Present data to user, advancing rcv_nxt through
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* completed sequence space.
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*/
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if (!TCPS_HAVEESTABLISHED(tp->t_state))
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return (0);
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q = LIST_FIRST(&tp->t_segq);
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if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
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return (0);
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SOCKBUF_LOCK(&so->so_rcv);
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do {
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tp->rcv_nxt += q->tqe_len;
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flags = q->tqe_th->th_flags & TH_FIN;
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nq = LIST_NEXT(q, tqe_q);
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LIST_REMOVE(q, tqe_q);
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if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
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m_freem(q->tqe_m);
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else
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sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
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if (q != &tqs)
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uma_zfree(tcp_reass_zone, q);
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tp->t_segqlen--;
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q = nq;
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} while (q && q->tqe_th->th_seq == tp->rcv_nxt);
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sorwakeup_locked(so);
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return (flags);
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}
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#endif
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