8f134647ca
in network byte order. Any host byte order processing is done in local variables and host byte order values are never[1] written to a packet. After this change a packet processed by the stack isn't modified at all[2] except for TTL. After this change a network stack hacker doesn't need to scratch his head trying to figure out what is the byte order at the given place in the stack. [1] One exception still remains. The raw sockets convert host byte order before pass a packet to an application. Probably this would remain for ages for compatibility. [2] The ip_input() still subtructs header len from ip->ip_len, but this is planned to be fixed soon. Reviewed by: luigi, Maxim Dounin <mdounin mdounin.ru> Tested by: ray, Olivier Cochard-Labbe <olivier cochard.me>
649 lines
16 KiB
C
649 lines
16 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 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_subr.c 8.2 (Berkeley) 5/24/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/callout.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/protosw.h>
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#include <sys/random.h>
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#include <vm/uma.h>
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#include <net/route.h>
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#include <net/if.h>
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#include <net/vnet.h>
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/ip_var.h>
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#ifdef INET6
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#include <netinet/ip6.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/scope6_var.h>
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#include <netinet6/nd6.h>
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#endif
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#ifdef INET6
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#include <netinet6/tcp6_var.h>
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#endif
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif
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#ifdef INET6
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#include <netinet6/ip6protosw.h>
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#endif
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#include <machine/in_cksum.h>
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#include <security/mac/mac_framework.h>
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static VNET_DEFINE(uma_zone_t, tcptw_zone);
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#define V_tcptw_zone VNET(tcptw_zone)
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static int maxtcptw;
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/*
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* The timed wait queue contains references to each of the TCP sessions
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* currently in the TIME_WAIT state. The queue pointers, including the
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* queue pointers in each tcptw structure, are protected using the global
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* tcbinfo lock, which must be held over queue iteration and modification.
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*/
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static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl);
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#define V_twq_2msl VNET(twq_2msl)
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static void tcp_tw_2msl_reset(struct tcptw *, int);
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static void tcp_tw_2msl_stop(struct tcptw *);
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static int
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tcptw_auto_size(void)
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{
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int halfrange;
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/*
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* Max out at half the ephemeral port range so that TIME_WAIT
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* sockets don't tie up too many ephemeral ports.
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*/
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if (V_ipport_lastauto > V_ipport_firstauto)
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halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
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else
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halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
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/* Protect against goofy port ranges smaller than 32. */
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return (imin(imax(halfrange, 32), maxsockets / 5));
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}
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static int
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sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
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{
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int error, new;
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if (maxtcptw == 0)
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new = tcptw_auto_size();
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else
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new = maxtcptw;
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error = sysctl_handle_int(oidp, &new, 0, req);
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if (error == 0 && req->newptr)
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if (new >= 32) {
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maxtcptw = new;
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uma_zone_set_max(V_tcptw_zone, maxtcptw);
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}
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return (error);
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}
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SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW,
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&maxtcptw, 0, sysctl_maxtcptw, "IU",
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"Maximum number of compressed TCP TIME_WAIT entries");
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VNET_DEFINE(int, nolocaltimewait) = 0;
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#define V_nolocaltimewait VNET(nolocaltimewait)
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
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&VNET_NAME(nolocaltimewait), 0,
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"Do not create compressed TCP TIME_WAIT entries for local connections");
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void
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tcp_tw_zone_change(void)
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{
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if (maxtcptw == 0)
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uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
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}
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void
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tcp_tw_init(void)
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{
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V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
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TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
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if (maxtcptw == 0)
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uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
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else
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uma_zone_set_max(V_tcptw_zone, maxtcptw);
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TAILQ_INIT(&V_twq_2msl);
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}
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#ifdef VIMAGE
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void
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tcp_tw_destroy(void)
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{
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struct tcptw *tw;
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INP_INFO_WLOCK(&V_tcbinfo);
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while((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
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tcp_twclose(tw, 0);
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INP_INFO_WUNLOCK(&V_tcbinfo);
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uma_zdestroy(V_tcptw_zone);
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}
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#endif
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/*
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* Move a TCP connection into TIME_WAIT state.
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* tcbinfo is locked.
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* inp is locked, and is unlocked before returning.
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*/
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void
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tcp_twstart(struct tcpcb *tp)
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{
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struct tcptw *tw;
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struct inpcb *inp = tp->t_inpcb;
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int acknow;
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struct socket *so;
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#ifdef INET6
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int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
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#endif
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INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_reset(). */
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INP_WLOCK_ASSERT(inp);
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if (V_nolocaltimewait) {
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int error = 0;
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#ifdef INET6
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if (isipv6)
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error = in6_localaddr(&inp->in6p_faddr);
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#endif
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#if defined(INET6) && defined(INET)
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else
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#endif
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#ifdef INET
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error = in_localip(inp->inp_faddr);
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#endif
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if (error) {
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tp = tcp_close(tp);
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if (tp != NULL)
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INP_WUNLOCK(inp);
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return;
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}
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}
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tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
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if (tw == NULL) {
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tw = tcp_tw_2msl_scan(1);
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if (tw == NULL) {
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tp = tcp_close(tp);
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if (tp != NULL)
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INP_WUNLOCK(inp);
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return;
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}
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}
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tw->tw_inpcb = inp;
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/*
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* Recover last window size sent.
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*/
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if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt))
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tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
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else
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tw->last_win = 0;
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/*
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* Set t_recent if timestamps are used on the connection.
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*/
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if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
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(TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
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tw->t_recent = tp->ts_recent;
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tw->ts_offset = tp->ts_offset;
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} else {
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tw->t_recent = 0;
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tw->ts_offset = 0;
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}
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tw->snd_nxt = tp->snd_nxt;
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tw->rcv_nxt = tp->rcv_nxt;
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tw->iss = tp->iss;
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tw->irs = tp->irs;
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tw->t_starttime = tp->t_starttime;
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tw->tw_time = 0;
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/* XXX
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* If this code will
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* be used for fin-wait-2 state also, then we may need
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* a ts_recent from the last segment.
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*/
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acknow = tp->t_flags & TF_ACKNOW;
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/*
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* First, discard tcpcb state, which includes stopping its timers and
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* freeing it. tcp_discardcb() used to also release the inpcb, but
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* that work is now done in the caller.
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*
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* Note: soisdisconnected() call used to be made in tcp_discardcb(),
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* and might not be needed here any longer.
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*/
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tcp_discardcb(tp);
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so = inp->inp_socket;
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soisdisconnected(so);
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tw->tw_cred = crhold(so->so_cred);
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SOCK_LOCK(so);
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tw->tw_so_options = so->so_options;
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SOCK_UNLOCK(so);
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if (acknow)
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tcp_twrespond(tw, TH_ACK);
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inp->inp_ppcb = tw;
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inp->inp_flags |= INP_TIMEWAIT;
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tcp_tw_2msl_reset(tw, 0);
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/*
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* If the inpcb owns the sole reference to the socket, then we can
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* detach and free the socket as it is not needed in time wait.
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*/
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if (inp->inp_flags & INP_SOCKREF) {
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KASSERT(so->so_state & SS_PROTOREF,
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("tcp_twstart: !SS_PROTOREF"));
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inp->inp_flags &= ~INP_SOCKREF;
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INP_WUNLOCK(inp);
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ACCEPT_LOCK();
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SOCK_LOCK(so);
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so->so_state &= ~SS_PROTOREF;
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sofree(so);
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} else
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INP_WUNLOCK(inp);
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}
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#if 0
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/*
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* The appromixate rate of ISN increase of Microsoft TCP stacks;
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* the actual rate is slightly higher due to the addition of
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* random positive increments.
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*
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* Most other new OSes use semi-randomized ISN values, so we
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* do not need to worry about them.
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*/
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#define MS_ISN_BYTES_PER_SECOND 250000
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/*
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* Determine if the ISN we will generate has advanced beyond the last
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* sequence number used by the previous connection. If so, indicate
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* that it is safe to recycle this tw socket by returning 1.
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*/
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int
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tcp_twrecycleable(struct tcptw *tw)
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{
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tcp_seq new_iss = tw->iss;
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tcp_seq new_irs = tw->irs;
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INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
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new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
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new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);
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if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
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return (1);
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else
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return (0);
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}
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#endif
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/*
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* Returns 1 if the TIME_WAIT state was killed and we should start over,
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* looking for a pcb in the listen state. Returns 0 otherwise.
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*/
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int
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tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
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struct mbuf *m, int tlen)
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{
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struct tcptw *tw;
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int thflags;
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tcp_seq seq;
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/* tcbinfo lock required for tcp_twclose(), tcp_tw_2msl_reset(). */
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INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
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INP_WLOCK_ASSERT(inp);
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/*
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* XXXRW: Time wait state for inpcb has been recycled, but inpcb is
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* still present. This is undesirable, but temporarily necessary
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* until we work out how to handle inpcb's who's timewait state has
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* been removed.
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*/
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tw = intotw(inp);
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if (tw == NULL)
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goto drop;
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thflags = th->th_flags;
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/*
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* NOTE: for FIN_WAIT_2 (to be added later),
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* must validate sequence number before accepting RST
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*/
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/*
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* If the segment contains RST:
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* Drop the segment - see Stevens, vol. 2, p. 964 and
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* RFC 1337.
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*/
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if (thflags & TH_RST)
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goto drop;
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#if 0
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/* PAWS not needed at the moment */
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/*
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* RFC 1323 PAWS: If we have a timestamp reply on this segment
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* and it's less than ts_recent, drop it.
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*/
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if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
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TSTMP_LT(to.to_tsval, tp->ts_recent)) {
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if ((thflags & TH_ACK) == 0)
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goto drop;
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goto ack;
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}
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/*
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* ts_recent is never updated because we never accept new segments.
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*/
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#endif
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/*
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* If a new connection request is received
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* while in TIME_WAIT, drop the old connection
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* and start over if the sequence numbers
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* are above the previous ones.
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*/
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if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
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tcp_twclose(tw, 0);
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return (1);
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}
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/*
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* Drop the segment if it does not contain an ACK.
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*/
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if ((thflags & TH_ACK) == 0)
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goto drop;
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/*
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* Reset the 2MSL timer if this is a duplicate FIN.
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*/
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if (thflags & TH_FIN) {
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seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
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if (seq + 1 == tw->rcv_nxt)
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tcp_tw_2msl_reset(tw, 1);
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}
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/*
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* Acknowledge the segment if it has data or is not a duplicate ACK.
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*/
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if (thflags != TH_ACK || tlen != 0 ||
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th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
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tcp_twrespond(tw, TH_ACK);
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drop:
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INP_WUNLOCK(inp);
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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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void
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tcp_twclose(struct tcptw *tw, int reuse)
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{
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struct socket *so;
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struct inpcb *inp;
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/*
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* At this point, we are in one of two situations:
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*
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* (1) We have no socket, just an inpcb<->twtcp pair. We can free
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* all state.
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*
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* (2) We have a socket -- if we own a reference, release it and
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* notify the socket layer.
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*/
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inp = tw->tw_inpcb;
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KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
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KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
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INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_stop(). */
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INP_WLOCK_ASSERT(inp);
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tw->tw_inpcb = NULL;
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tcp_tw_2msl_stop(tw);
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inp->inp_ppcb = NULL;
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in_pcbdrop(inp);
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so = inp->inp_socket;
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if (so != NULL) {
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/*
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* If there's a socket, handle two cases: first, we own a
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* strong reference, which we will now release, or we don't
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* in which case another reference exists (XXXRW: think
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* about this more), and we don't need to take action.
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*/
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if (inp->inp_flags & INP_SOCKREF) {
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inp->inp_flags &= ~INP_SOCKREF;
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INP_WUNLOCK(inp);
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ACCEPT_LOCK();
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SOCK_LOCK(so);
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KASSERT(so->so_state & SS_PROTOREF,
|
|
("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
|
|
so->so_state &= ~SS_PROTOREF;
|
|
sofree(so);
|
|
} else {
|
|
/*
|
|
* If we don't own the only reference, the socket and
|
|
* inpcb need to be left around to be handled by
|
|
* tcp_usr_detach() later.
|
|
*/
|
|
INP_WUNLOCK(inp);
|
|
}
|
|
} else
|
|
in_pcbfree(inp);
|
|
TCPSTAT_INC(tcps_closed);
|
|
crfree(tw->tw_cred);
|
|
tw->tw_cred = NULL;
|
|
if (reuse)
|
|
return;
|
|
uma_zfree(V_tcptw_zone, tw);
|
|
}
|
|
|
|
int
|
|
tcp_twrespond(struct tcptw *tw, int flags)
|
|
{
|
|
struct inpcb *inp = tw->tw_inpcb;
|
|
#if defined(INET6) || defined(INET)
|
|
struct tcphdr *th = NULL;
|
|
#endif
|
|
struct mbuf *m;
|
|
#ifdef INET
|
|
struct ip *ip = NULL;
|
|
#endif
|
|
u_int hdrlen, optlen;
|
|
int error = 0; /* Keep compiler happy */
|
|
struct tcpopt to;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6 = NULL;
|
|
int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
|
|
#endif
|
|
|
|
INP_WLOCK_ASSERT(inp);
|
|
|
|
m = m_gethdr(M_DONTWAIT, MT_DATA);
|
|
if (m == NULL)
|
|
return (ENOBUFS);
|
|
m->m_data += max_linkhdr;
|
|
|
|
#ifdef MAC
|
|
mac_inpcb_create_mbuf(inp, m);
|
|
#endif
|
|
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
th = (struct tcphdr *)(ip6 + 1);
|
|
tcpip_fillheaders(inp, ip6, th);
|
|
}
|
|
#endif
|
|
#if defined(INET6) && defined(INET)
|
|
else
|
|
#endif
|
|
#ifdef INET
|
|
{
|
|
hdrlen = sizeof(struct tcpiphdr);
|
|
ip = mtod(m, struct ip *);
|
|
th = (struct tcphdr *)(ip + 1);
|
|
tcpip_fillheaders(inp, ip, th);
|
|
}
|
|
#endif
|
|
to.to_flags = 0;
|
|
|
|
/*
|
|
* Send a timestamp and echo-reply if both our side and our peer
|
|
* have sent timestamps in our SYN's and this is not a RST.
|
|
*/
|
|
if (tw->t_recent && flags == TH_ACK) {
|
|
to.to_flags |= TOF_TS;
|
|
to.to_tsval = tcp_ts_getticks() + tw->ts_offset;
|
|
to.to_tsecr = tw->t_recent;
|
|
}
|
|
optlen = tcp_addoptions(&to, (u_char *)(th + 1));
|
|
|
|
m->m_len = hdrlen + optlen;
|
|
m->m_pkthdr.len = m->m_len;
|
|
|
|
KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
|
|
|
|
th->th_seq = htonl(tw->snd_nxt);
|
|
th->th_ack = htonl(tw->rcv_nxt);
|
|
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
|
|
th->th_flags = flags;
|
|
th->th_win = htons(tw->last_win);
|
|
|
|
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
|
|
th->th_sum = in6_cksum_pseudo(ip6,
|
|
sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0);
|
|
ip6->ip6_hlim = in6_selecthlim(inp, NULL);
|
|
error = ip6_output(m, inp->in6p_outputopts, NULL,
|
|
(tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
|
|
}
|
|
#endif
|
|
#if defined(INET6) && defined(INET)
|
|
else
|
|
#endif
|
|
#ifdef INET
|
|
{
|
|
m->m_pkthdr.csum_flags = CSUM_TCP;
|
|
th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
|
|
htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
|
|
ip->ip_len = htons(m->m_pkthdr.len);
|
|
if (V_path_mtu_discovery)
|
|
ip->ip_off |= htons(IP_DF);
|
|
error = ip_output(m, inp->inp_options, NULL,
|
|
((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
|
|
NULL, inp);
|
|
}
|
|
#endif
|
|
if (flags & TH_ACK)
|
|
TCPSTAT_INC(tcps_sndacks);
|
|
else
|
|
TCPSTAT_INC(tcps_sndctrl);
|
|
TCPSTAT_INC(tcps_sndtotal);
|
|
return (error);
|
|
}
|
|
|
|
static void
|
|
tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
|
|
{
|
|
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
INP_WLOCK_ASSERT(tw->tw_inpcb);
|
|
if (rearm)
|
|
TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
|
|
tw->tw_time = ticks + 2 * tcp_msl;
|
|
TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
|
|
}
|
|
|
|
static void
|
|
tcp_tw_2msl_stop(struct tcptw *tw)
|
|
{
|
|
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
|
|
}
|
|
|
|
struct tcptw *
|
|
tcp_tw_2msl_scan(int reuse)
|
|
{
|
|
struct tcptw *tw;
|
|
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
for (;;) {
|
|
tw = TAILQ_FIRST(&V_twq_2msl);
|
|
if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0))
|
|
break;
|
|
INP_WLOCK(tw->tw_inpcb);
|
|
tcp_twclose(tw, reuse);
|
|
if (reuse)
|
|
return (tw);
|
|
}
|
|
return (NULL);
|
|
}
|