diff options
Diffstat (limited to 'sys/netinet/tcp_reass.c')
| -rw-r--r-- | sys/netinet/tcp_reass.c | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c new file mode 100644 index 0000000..5fd29b8 --- /dev/null +++ b/sys/netinet/tcp_reass.c @@ -0,0 +1,362 @@ +/*- + * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_inet.h" +#include "opt_inet6.h" +#include "opt_tcpdebug.h" + +#include <sys/param.h> +#include <sys/kernel.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/sysctl.h> +#include <sys/syslog.h> +#include <sys/systm.h> + +#include <vm/uma.h> + +#include <net/if.h> +#include <net/route.h> +#include <net/vnet.h> + +#include <netinet/in.h> +#include <netinet/in_pcb.h> +#include <netinet/in_systm.h> +#include <netinet/in_var.h> +#include <netinet/ip.h> +#include <netinet/ip_var.h> +#include <netinet/ip_options.h> +#include <netinet/ip6.h> +#include <netinet6/in6_pcb.h> +#include <netinet6/ip6_var.h> +#include <netinet6/nd6.h> +#include <netinet/tcp.h> +#include <netinet/tcp_fsm.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet6/tcp6_var.h> +#include <netinet/tcpip.h> +#ifdef TCPDEBUG +#include <netinet/tcp_debug.h> +#endif /* TCPDEBUG */ + +static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS); + +static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, + "TCP Segment Reassembly Queue"); + +static VNET_DEFINE(int, tcp_reass_maxseg) = 0; +#define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) +SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, + &VNET_NAME(tcp_reass_maxseg), 0, + "Global maximum number of TCP Segments in Reassembly Queue"); + +SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, + (CTLTYPE_INT | CTLFLAG_RD), NULL, 0, &tcp_reass_sysctl_qsize, "I", + "Global number of TCP Segments currently in Reassembly Queue"); + +static VNET_DEFINE(int, tcp_reass_overflows) = 0; +#define V_tcp_reass_overflows VNET(tcp_reass_overflows) +SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, + CTLTYPE_INT | CTLFLAG_RD, + &VNET_NAME(tcp_reass_overflows), 0, + "Global number of TCP Segment Reassembly Queue Overflows"); + +static VNET_DEFINE(uma_zone_t, tcp_reass_zone); +#define V_tcp_reass_zone VNET(tcp_reass_zone) + +/* Initialize TCP reassembly queue */ +static void +tcp_reass_zone_change(void *tag) +{ + + /* Set the zone limit and read back the effective value. */ + V_tcp_reass_maxseg = nmbclusters / 16; + V_tcp_reass_maxseg = uma_zone_set_max(V_tcp_reass_zone, + V_tcp_reass_maxseg); +} + +void +tcp_reass_init(void) +{ + + V_tcp_reass_maxseg = nmbclusters / 16; + TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", + &V_tcp_reass_maxseg); + V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), + NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); + /* Set the zone limit and read back the effective value. */ + V_tcp_reass_maxseg = uma_zone_set_max(V_tcp_reass_zone, + V_tcp_reass_maxseg); + EVENTHANDLER_REGISTER(nmbclusters_change, + tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); +} + +#ifdef VIMAGE +void +tcp_reass_destroy(void) +{ + + uma_zdestroy(V_tcp_reass_zone); +} +#endif + +void +tcp_reass_flush(struct tcpcb *tp) +{ + struct tseg_qent *qe; + + INP_WLOCK_ASSERT(tp->t_inpcb); + + while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { + LIST_REMOVE(qe, tqe_q); + m_freem(qe->tqe_m); + uma_zfree(V_tcp_reass_zone, qe); + tp->t_segqlen--; + } + + KASSERT((tp->t_segqlen == 0), + ("TCP reass queue %p segment count is %d instead of 0 after flush.", + tp, tp->t_segqlen)); +} + +static int +tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS) +{ + int qsize; + + qsize = uma_zone_get_cur(V_tcp_reass_zone); + return (sysctl_handle_int(oidp, &qsize, 0, req)); +} + +int +tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) +{ + struct tseg_qent *q; + struct tseg_qent *p = NULL; + struct tseg_qent *nq; + struct tseg_qent *te = NULL; + struct socket *so = tp->t_inpcb->inp_socket; + char *s = NULL; + int flags; + struct tseg_qent tqs; + + INP_WLOCK_ASSERT(tp->t_inpcb); + + /* + * XXX: tcp_reass() is rather inefficient with its data structures + * and should be rewritten (see NetBSD for optimizations). + */ + + /* + * Call with th==NULL after become established to + * force pre-ESTABLISHED data up to user socket. + */ + if (th == NULL) + goto present; + + /* + * Limit the number of segments that can be queued to reduce the + * potential for mbuf exhaustion. For best performance, we want to be + * able to queue a full window's worth of segments. The size of the + * socket receive buffer determines our advertised window and grows + * automatically when socket buffer autotuning is enabled. Use it as the + * basis for our queue limit. + * Always let the missing segment through which caused this queue. + * NB: Access to the socket buffer is left intentionally unlocked as we + * can tolerate stale information here. + * + * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat + * should work but causes packets to be dropped when they shouldn't. + * Investigate why and re-evaluate the below limit after the behaviour + * is understood. + */ + if (th->th_seq != tp->rcv_nxt && + tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { + V_tcp_reass_overflows++; + TCPSTAT_INC(tcps_rcvmemdrop); + m_freem(m); + *tlenp = 0; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { + log(LOG_DEBUG, "%s; %s: queue limit reached, " + "segment dropped\n", s, __func__); + free(s, M_TCPLOG); + } + return (0); + } + + /* + * Allocate a new queue entry. If we can't, or hit the zone limit + * just drop the pkt. + * + * Use a temporary structure on the stack for the missing segment + * when the zone is exhausted. Otherwise we may get stuck. + */ + te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); + if (te == NULL) { + if (th->th_seq != tp->rcv_nxt) { + TCPSTAT_INC(tcps_rcvmemdrop); + m_freem(m); + *tlenp = 0; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, + NULL))) { + log(LOG_DEBUG, "%s; %s: global zone limit " + "reached, segment dropped\n", s, __func__); + free(s, M_TCPLOG); + } + return (0); + } else { + bzero(&tqs, sizeof(struct tseg_qent)); + te = &tqs; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, + NULL))) { + log(LOG_DEBUG, + "%s; %s: global zone limit reached, using " + "stack for missing segment\n", s, __func__); + free(s, M_TCPLOG); + } + } + } + tp->t_segqlen++; + + /* + * Find a segment which begins after this one does. + */ + LIST_FOREACH(q, &tp->t_segq, tqe_q) { + if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) + break; + p = q; + } + + /* + * If there is a preceding segment, it may provide some of + * our data already. If so, drop the data from the incoming + * segment. If it provides all of our data, drop us. + */ + if (p != NULL) { + int i; + /* conversion to int (in i) handles seq wraparound */ + i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; + if (i > 0) { + if (i >= *tlenp) { + TCPSTAT_INC(tcps_rcvduppack); + TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); + m_freem(m); + uma_zfree(V_tcp_reass_zone, te); + tp->t_segqlen--; + /* + * Try to present any queued data + * at the left window edge to the user. + * This is needed after the 3-WHS + * completes. + */ + goto present; /* ??? */ + } + m_adj(m, i); + *tlenp -= i; + th->th_seq += i; + } + } + tp->t_rcvoopack++; + TCPSTAT_INC(tcps_rcvoopack); + TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); + + /* + * While we overlap succeeding segments trim them or, + * if they are completely covered, dequeue them. + */ + while (q) { + int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; + if (i <= 0) + break; + if (i < q->tqe_len) { + q->tqe_th->th_seq += i; + q->tqe_len -= i; + m_adj(q->tqe_m, i); + break; + } + + nq = LIST_NEXT(q, tqe_q); + LIST_REMOVE(q, tqe_q); + m_freem(q->tqe_m); + uma_zfree(V_tcp_reass_zone, q); + tp->t_segqlen--; + q = nq; + } + + /* Insert the new segment queue entry into place. */ + te->tqe_m = m; + te->tqe_th = th; + te->tqe_len = *tlenp; + + if (p == NULL) { + LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); + } else { + KASSERT(te != &tqs, ("%s: temporary stack based entry not " + "first element in queue", __func__)); + LIST_INSERT_AFTER(p, te, tqe_q); + } + +present: + /* + * Present data to user, advancing rcv_nxt through + * completed sequence space. + */ + if (!TCPS_HAVEESTABLISHED(tp->t_state)) + return (0); + q = LIST_FIRST(&tp->t_segq); + if (!q || q->tqe_th->th_seq != tp->rcv_nxt) + return (0); + SOCKBUF_LOCK(&so->so_rcv); + do { + tp->rcv_nxt += q->tqe_len; + flags = q->tqe_th->th_flags & TH_FIN; + nq = LIST_NEXT(q, tqe_q); + LIST_REMOVE(q, tqe_q); + if (so->so_rcv.sb_state & SBS_CANTRCVMORE) + m_freem(q->tqe_m); + else + sbappendstream_locked(&so->so_rcv, q->tqe_m); + if (q != &tqs) + uma_zfree(V_tcp_reass_zone, q); + tp->t_segqlen--; + q = nq; + } while (q && q->tqe_th->th_seq == tp->rcv_nxt); + ND6_HINT(tp); + sorwakeup_locked(so); + return (flags); +} |
