#ifndef ORIG #include #include "bsd_only.h" #endif /* $NetBSD: tcp_subr.c,v 1.65 1999/01/26 08:28:50 thorpej Exp $ */ /*- * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation * Facility, NASA Ames Research Center. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993, 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 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_subr.c 8.2 (Berkeley) 5/24/95 */ #include "opt_tcp_compat_42.h" #include "rnd.h" #include #include #include #include #include #include #include #include #include #include #include #if NRND > 0 #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* patchable/settable parameters for tcp */ int tcp_mssdflt = TCP_MSS; int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; int tcp_do_rfc1323 = 1; /* window scaling / timestamps (obsolete) */ int tcp_do_sack = 1; /* selective acknowledgement */ int tcp_do_win_scale = 1; /* RFC1323 window scaling */ int tcp_do_timestamps = 1; /* RFC1323 timestamps */ int tcp_do_newreno = 0; /* Use the New Reno algorithms */ int tcp_ack_on_push = 0; /* set to enable immediate ACK-on-PUSH */ int tcp_init_win = 1; int tcp_mss_ifmtu = 0; #ifdef TCP_COMPAT_42 int tcp_compat_42 = 1; #else int tcp_compat_42 = 0; #endif #ifndef TCBHASHSIZE #define TCBHASHSIZE 128 #endif int tcbhashsize = TCBHASHSIZE; int tcp_freeq __P((struct tcpcb *)); struct pool tcpcb_pool; struct pool tcp_template_pool; /* * Tcp initialization */ void tcp_init() { dbg_trace("tcp_init\n"); pool_init(&tcpcb_pool, sizeof(struct tcpcb), 0, 0, 0, "tcpcbpl", 0, NULL, NULL, M_PCB); pool_init(&tcp_template_pool, sizeof(struct tcpiphdr), 0, 0, 0, "tcptmpl", 0, NULL, NULL, M_MBUF); in_pcbinit(&tcbtable, tcbhashsize, tcbhashsize); LIST_INIT(&tcp_delacks); if (max_protohdr < sizeof(struct tcpiphdr)) max_protohdr = sizeof(struct tcpiphdr); if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) panic("tcp_init"); /* Initialize the compressed state engine. */ syn_cache_init(); } /* * Create template to be used to send tcp packets on a connection. * Call after host entry created, allocates an mbuf and fills * in a skeletal tcp/ip header, minimizing the amount of work * necessary when the connection is used. */ struct tcpiphdr * tcp_template(tp) struct tcpcb *tp; { register struct inpcb *inp = tp->t_inpcb; register struct tcpiphdr *n; if ((n = tp->t_template) == 0) { n = pool_get(&tcp_template_pool, PR_NOWAIT); if (n == NULL) return (NULL); } bzero(n->ti_x1, sizeof n->ti_x1); n->ti_pr = IPPROTO_TCP; n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); n->ti_src = inp->inp_laddr; n->ti_dst = inp->inp_faddr; n->ti_sport = inp->inp_lport; n->ti_dport = inp->inp_fport; n->ti_seq = 0; n->ti_ack = 0; n->ti_x2 = 0; n->ti_off = 5; n->ti_flags = 0; n->ti_win = 0; n->ti_sum = 0; n->ti_urp = 0; return (n); } /* * Send a single message to the TCP at address specified by * the given TCP/IP header. If m == 0, then we make a copy * of the tcpiphdr at ti and send directly to the addressed host. * This is used to force keep alive messages out using the TCP * template for a connection tp->t_template. If flags are given * then we send a message back to the TCP which originated the * segment ti, and discard the mbuf containing it and any other * attached mbufs. * * In any case the ack and sequence number of the transmitted * segment are as specified by the parameters. */ int tcp_respond(tp, ti, m, ack, seq, flags) struct tcpcb *tp; register struct tcpiphdr *ti; register struct mbuf *m; tcp_seq ack, seq; int flags; { struct route iproute, *ro; struct rtentry *rt; struct sockaddr_in *dst; int error, tlen, win = 0; if (tp != NULL && (flags & TH_RST) == 0) win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); if (m == 0) { m = m_gethdr(M_DONTWAIT, MT_HEADER); if (m == NULL) return (ENOBUFS); if (tcp_compat_42) tlen = 1; else tlen = 0; m->m_data += max_linkhdr; *mtod(m, struct tcpiphdr *) = *ti; ti = mtod(m, struct tcpiphdr *); flags = TH_ACK; } else { m_freem(m->m_next); m->m_next = 0; m->m_data = (caddr_t)ti; m->m_len = sizeof (struct tcpiphdr); tlen = 0; #define xchg(a,b,type) { type t; t=a; a=b; b=t; } xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t); xchg(ti->ti_dport, ti->ti_sport, u_int16_t); #undef xchg } bzero(ti->ti_x1, sizeof ti->ti_x1); ti->ti_seq = htonl(seq); ti->ti_ack = htonl(ack); ti->ti_x2 = 0; if ((flags & TH_SYN) == 0) { if (tp) ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale)); else ti->ti_win = htons((u_int16_t)win); ti->ti_off = sizeof (struct tcphdr) >> 2; tlen += sizeof (struct tcphdr); } else tlen += ti->ti_off << 2; ti->ti_len = htons((u_int16_t)tlen); tlen += sizeof (struct ip); m->m_len = tlen; m->m_pkthdr.len = tlen; m->m_pkthdr.rcvif = (struct ifnet *) 0; ti->ti_flags = flags; ti->ti_urp = 0; ti->ti_sum = 0; ti->ti_sum = in_cksum(m, tlen); ((struct ip *)ti)->ip_len = tlen; ((struct ip *)ti)->ip_ttl = ip_defttl; /* * If we're doing Path MTU discovery, we need to set DF unless * the route's MTU is locked. If we lack a route, we need to * look it up now. * * ip_output() could do this for us, but it's convenient to just * do it here unconditionally. */ if (tp != NULL) { ro = &tp->t_inpcb->inp_route; #ifdef DIAGNOSTIC if (!in_hosteq(ti->ti_dst, tp->t_inpcb->inp_faddr)) panic("tcp_respond: ti_dst %x != inp_faddr %x", ntohl(ti->ti_dst.s_addr), ntohl(tp->t_inpcb->inp_faddr.s_addr)); #endif } else { ro = &iproute; bzero(ro, sizeof(*ro)); } if ((rt = ro->ro_rt) == NULL || (rt->rt_flags & RTF_UP) == 0) { if (ro->ro_rt != NULL) { RTFREE(ro->ro_rt); ro->ro_rt = NULL; } dst = satosin(&ro->ro_dst); dst->sin_family = AF_INET; dst->sin_len = sizeof(*dst); dst->sin_addr = ti->ti_dst; rtalloc(ro); if ((rt = ro->ro_rt) == NULL) { m_freem(m); ipstat.ips_noroute++; return (EHOSTUNREACH); } } if (ip_mtudisc != 0 && (rt->rt_rmx.rmx_locks & RTV_MTU) == 0) ((struct ip *)ti)->ip_off |= IP_DF; error = ip_output(m, NULL, ro, 0, NULL); if (ro == &iproute) { RTFREE(ro->ro_rt); ro->ro_rt = NULL; } return (error); } /* * Create a new TCP control block, making an * empty reassembly queue and hooking it to the argument * protocol control block. */ struct tcpcb * tcp_newtcpcb(inp) struct inpcb *inp; { register struct tcpcb *tp; tp = pool_get(&tcpcb_pool, PR_NOWAIT); if (tp == NULL) return (NULL); bzero((caddr_t)tp, sizeof(struct tcpcb)); LIST_INIT(&tp->segq); LIST_INIT(&tp->timeq); tp->t_peermss = tcp_mssdflt; tp->t_ourmss = tcp_mssdflt; tp->t_segsz = tcp_mssdflt; tp->t_flags = 0; if (tcp_do_rfc1323 && tcp_do_win_scale) tp->t_flags |= TF_REQ_SCALE; if (tcp_do_rfc1323 && tcp_do_timestamps) tp->t_flags |= TF_REQ_TSTMP; if (tcp_do_sack == 2) tp->t_flags |= TF_WILL_SACK; else if (tcp_do_sack == 1) tp->t_flags |= TF_WILL_SACK|TF_IGNR_RXSACK; tp->t_flags |= TF_CANT_TXSACK; tp->t_inpcb = inp; /* * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives * reasonable initial retransmit time. */ tp->t_srtt = TCPTV_SRTTBASE; tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << (TCP_RTTVAR_SHIFT + 2 - 1); tp->t_rttmin = TCPTV_MIN; TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), TCPTV_MIN, TCPTV_REXMTMAX); tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; inp->inp_ip.ip_ttl = ip_defttl; inp->inp_ppcb = (caddr_t)tp; return (tp); } /* * Drop a TCP connection, reporting * the specified error. If connection is synchronized, * then send a RST to peer. */ struct tcpcb * tcp_drop(tp, errno) register struct tcpcb *tp; int errno; { struct socket *so = tp->t_inpcb->inp_socket; if (TCPS_HAVERCVDSYN(tp->t_state)) { tp->t_state = TCPS_CLOSED; (void) tcp_output(tp); tcpstat.tcps_drops++; } else tcpstat.tcps_conndrops++; if (errno == ETIMEDOUT && tp->t_softerror) errno = tp->t_softerror; so->so_error = errno; return (tcp_close(tp)); } /* * Close a TCP control block: * discard all space held by the tcp * discard internet protocol block * wake up any sleepers */ struct tcpcb * tcp_close(tp) register struct tcpcb *tp; { struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; #ifdef RTV_RTT register struct rtentry *rt; /* * If we sent enough data to get some meaningful characteristics, * save them in the routing entry. 'Enough' is arbitrarily * defined as the sendpipesize (default 4K) * 16. This would * give us 16 rtt samples assuming we only get one sample per * window (the usual case on a long haul net). 16 samples is * enough for the srtt filter to converge to within 5% of the correct * value; fewer samples and we could save a very bogus rtt. * * Don't update the default route's characteristics and don't * update anything that the user "locked". */ if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && (rt = inp->inp_route.ro_rt) && !in_nullhost(satosin(rt_key(rt))->sin_addr)) { register u_long i = 0; if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { i = tp->t_srtt * ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); if (rt->rt_rmx.rmx_rtt && i) /* * filter this update to half the old & half * the new values, converting scale. * See route.h and tcp_var.h for a * description of the scaling constants. */ rt->rt_rmx.rmx_rtt = (rt->rt_rmx.rmx_rtt + i) / 2; else rt->rt_rmx.rmx_rtt = i; } if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { i = tp->t_rttvar * ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2)); if (rt->rt_rmx.rmx_rttvar && i) rt->rt_rmx.rmx_rttvar = (rt->rt_rmx.rmx_rttvar + i) / 2; else rt->rt_rmx.rmx_rttvar = i; } /* * update the pipelimit (ssthresh) if it has been updated * already or if a pipesize was specified & the threshhold * got below half the pipesize. I.e., wait for bad news * before we start updating, then update on both good * and bad news. */ if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh) || i < (rt->rt_rmx.rmx_sendpipe / 2)) { /* * convert the limit from user data bytes to * packets then to packet data bytes. */ i = (i + tp->t_segsz / 2) / tp->t_segsz; if (i < 2) i = 2; i *= (u_long)(tp->t_segsz + sizeof (struct tcpiphdr)); if (rt->rt_rmx.rmx_ssthresh) rt->rt_rmx.rmx_ssthresh = (rt->rt_rmx.rmx_ssthresh + i) / 2; else rt->rt_rmx.rmx_ssthresh = i; } } #endif /* RTV_RTT */ /* free the reassembly queue, if any */ TCP_REASS_LOCK(tp); (void) tcp_freeq(tp); TCP_REASS_UNLOCK(tp); TCP_CLEAR_DELACK(tp); if (tp->t_template) pool_put(&tcp_template_pool, tp->t_template); pool_put(&tcpcb_pool, tp); inp->inp_ppcb = 0; soisdisconnected(so); in_pcbdetach(inp); tcpstat.tcps_closed++; return ((struct tcpcb *)0); } int tcp_freeq(tp) struct tcpcb *tp; { register struct ipqent *qe; int rv = 0; #ifdef TCPREASS_DEBUG int i = 0; #endif TCP_REASS_LOCK_CHECK(tp); while ((qe = tp->segq.lh_first) != NULL) { #ifdef TCPREASS_DEBUG printf("tcp_freeq[%p,%d]: %u:%u(%u) 0x%02x\n", tp, i++, qe->ipqe_seq, qe->ipqe_seq + qe->ipqe_len, qe->ipqe_len, qe->ipqe_flags & (TH_SYN|TH_FIN|TH_RST)); #endif LIST_REMOVE(qe, ipqe_q); LIST_REMOVE(qe, ipqe_timeq); m_freem(qe->ipqe_m); pool_put(&ipqent_pool, qe); rv = 1; } return (rv); } /* * Protocol drain routine. Called when memory is in short supply. */ void tcp_drain() { register struct inpcb *inp; register struct tcpcb *tp; /* * Free the sequence queue of all TCP connections. */ inp = tcbtable.inpt_queue.cqh_first; if (inp) /* XXX */ for (; inp != (struct inpcb *)&tcbtable.inpt_queue; inp = inp->inp_queue.cqe_next) { if ((tp = intotcpcb(inp)) != NULL) { /* * We may be called from a device's interrupt * context. If the tcpcb is already busy, * just bail out now. */ if (tcp_reass_lock_try(tp) == 0) continue; if (tcp_freeq(tp)) tcpstat.tcps_connsdrained++; TCP_REASS_UNLOCK(tp); } } } /* * Notify a tcp user of an asynchronous error; * store error as soft error, but wake up user * (for now, won't do anything until can select for soft error). */ void tcp_notify(inp, error) struct inpcb *inp; int error; { register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; register struct socket *so = inp->inp_socket; /* * Ignore some errors if we are hooked up. * If connection hasn't completed, has retransmitted several times, * and receives a second error, give up now. This is better * than waiting a long time to establish a connection that * can never complete. */ if (tp->t_state == TCPS_ESTABLISHED && (error == EHOSTUNREACH || error == ENETUNREACH || error == EHOSTDOWN)) { return; } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 && tp->t_rxtshift > 3 && tp->t_softerror) so->so_error = error; else tp->t_softerror = error; wakeup((caddr_t) &so->so_timeo); sorwakeup(so); sowwakeup(so); } void * tcp_ctlinput(cmd, sa, v) int cmd; struct sockaddr *sa; register void *v; { register struct ip *ip = v; register struct tcphdr *th; extern int inetctlerrmap[]; void (*notify) __P((struct inpcb *, int)) = tcp_notify; int errno; int nmatch; if ((unsigned)cmd >= PRC_NCMDS) return NULL; errno = inetctlerrmap[cmd]; if (cmd == PRC_QUENCH) notify = tcp_quench; else if (PRC_IS_REDIRECT(cmd)) notify = in_rtchange, ip = 0; else if (cmd == PRC_MSGSIZE && ip_mtudisc) notify = tcp_mtudisc, ip = 0; else if (cmd == PRC_HOSTDEAD) ip = 0; else if (errno == 0) return NULL; if (ip) { th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); nmatch = in_pcbnotify(&tcbtable, satosin(sa)->sin_addr, th->th_dport, ip->ip_src, th->th_sport, errno, notify); if (nmatch == 0 && syn_cache_count && (inetctlerrmap[cmd] == EHOSTUNREACH || inetctlerrmap[cmd] == ENETUNREACH || inetctlerrmap[cmd] == EHOSTDOWN)) syn_cache_unreach(ip, th); } else (void)in_pcbnotifyall(&tcbtable, satosin(sa)->sin_addr, errno, notify); return NULL; } /* * When a source quence is received, we are being notifed of congestion. * Close the congestion window down to the Loss Window (one segment). * We will gradually open it again as we proceed. */ void tcp_quench(inp, errno) struct inpcb *inp; int errno; { struct tcpcb *tp = intotcpcb(inp); if (tp) tp->snd_cwnd = tp->t_segsz; } /* * On receipt of path MTU corrections, flush old route and replace it * with the new one. Retransmit all unacknowledged packets, to ensure * that all packets will be received. */ void tcp_mtudisc(inp, errno) struct inpcb *inp; int errno; { struct tcpcb *tp = intotcpcb(inp); struct rtentry *rt = in_pcbrtentry(inp); if (tp != 0) { if (rt != 0) { /* * If this was not a host route, remove and realloc. */ if ((rt->rt_flags & RTF_HOST) == 0) { in_rtchange(inp, errno); if ((rt = in_pcbrtentry(inp)) == 0) return; } /* * Slow start out of the error condition. We * use the MTU because we know it's smaller * than the previously transmitted segment. * * Note: This is more conservative than the * suggestion in draft-floyd-incr-init-win-03. */ if (rt->rt_rmx.rmx_mtu != 0) tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, rt->rt_rmx.rmx_mtu); } /* * Resend unacknowledged packets. */ tp->snd_nxt = tp->snd_una; tcp_output(tp); } } /* * Compute the MSS to advertise to the peer. Called only during * the 3-way handshake. If we are the server (peer initiated * connection), we are called with a pointer to the interface * on which the SYN packet arrived. If we are the client (we * initiated connection), we are called with a pointer to the * interface out which this connection should go. */ u_long tcp_mss_to_advertise(ifp) const struct ifnet *ifp; { extern u_long in_maxmtu; u_long mss = 0; /* * In order to avoid defeating path MTU discovery on the peer, * we advertise the max MTU of all attached networks as our MSS, * per RFC 1191, section 3.1. * * We provide the option to advertise just the MTU of * the interface on which we hope this connection will * be receiving. If we are responding to a SYN, we * will have a pretty good idea about this, but when * initiating a connection there is a bit more doubt. * * We also need to ensure that loopback has a large enough * MSS, as the loopback MTU is never included in in_maxmtu. */ if (ifp != NULL) mss = ifp->if_mtu; if (tcp_mss_ifmtu == 0) mss = max(in_maxmtu, mss); if (mss > sizeof(struct tcpiphdr)) mss -= sizeof(struct tcpiphdr); mss = max(tcp_mssdflt, mss); return (mss); } /* * Set connection variables based on the peer's advertised MSS. * We are passed the TCPCB for the actual connection. If we * are the server, we are called by the compressed state engine * when the 3-way handshake is complete. If we are the client, * we are called when we recieve the SYN,ACK from the server. * * NOTE: Our advertised MSS value must be initialized in the TCPCB * before this routine is called! */ void tcp_mss_from_peer(tp, offer) struct tcpcb *tp; int offer; { struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH) struct rtentry *rt = in_pcbrtentry(inp); #endif u_long bufsize; int mss; /* * As per RFC1122, use the default MSS value, unless they * sent us an offer. Do not accept offers less than 32 bytes. */ mss = tcp_mssdflt; if (offer) mss = offer; mss = max(mss, 32); /* sanity */ tp->t_peermss = mss; mss -= (tcp_optlen(tp) + ip_optlen(tp->t_inpcb)); /* * If there's a pipesize, change the socket buffer to that size. * Make the socket buffer an integral number of MSS units. If * the MSS is larger than the socket buffer, artificially decrease * the MSS. */ #ifdef RTV_SPIPE if (rt != NULL && rt->rt_rmx.rmx_sendpipe != 0) bufsize = rt->rt_rmx.rmx_sendpipe; else #endif bufsize = so->so_snd.sb_hiwat; if (bufsize < mss) mss = bufsize; else { bufsize = roundup(bufsize, mss); if (bufsize > sb_max) bufsize = sb_max; (void) sbreserve(&so->so_snd, bufsize); } tp->t_segsz = mss; #ifdef RTV_SSTHRESH if (rt != NULL && rt->rt_rmx.rmx_ssthresh) { /* * There's some sort of gateway or interface buffer * limit on the path. Use this to set the slow * start threshold, but set the threshold to no less * than 2 * MSS. */ tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); } #endif } /* * Processing necessary when a TCP connection is established. */ void tcp_established(tp) struct tcpcb *tp; { struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; #ifdef RTV_RPIPE struct rtentry *rt = in_pcbrtentry(inp); #endif u_long bufsize; tp->t_state = TCPS_ESTABLISHED; TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); #ifdef RTV_RPIPE if (rt != NULL && rt->rt_rmx.rmx_recvpipe != 0) bufsize = rt->rt_rmx.rmx_recvpipe; else #endif bufsize = so->so_rcv.sb_hiwat; if (bufsize > tp->t_ourmss) { bufsize = roundup(bufsize, tp->t_ourmss); if (bufsize > sb_max) bufsize = sb_max; (void) sbreserve(&so->so_rcv, bufsize); } } /* * Check if there's an initial rtt or rttvar. Convert from the * route-table units to scaled multiples of the slow timeout timer. * Called only during the 3-way handshake. */ void tcp_rmx_rtt(tp) struct tcpcb *tp; { #ifdef RTV_RTT struct rtentry *rt; int rtt; if ((rt = in_pcbrtentry(tp->t_inpcb)) == NULL) return; if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { /* * XXX The lock bit for MTU indicates that the value * is also a minimum value; this is subject to time. */ if (rt->rt_rmx.rmx_locks & RTV_RTT) TCPT_RANGESET(tp->t_rttmin, rtt / (RTM_RTTUNIT / PR_SLOWHZ), TCPTV_MIN, TCPTV_REXMTMAX); tp->t_srtt = rtt / ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); if (rt->rt_rmx.rmx_rttvar) { tp->t_rttvar = rt->rt_rmx.rmx_rttvar / ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2)); } else { /* Default variation is +- 1 rtt */ tp->t_rttvar = tp->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT); } TCPT_RANGESET(tp->t_rxtcur, ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2), tp->t_rttmin, TCPTV_REXMTMAX); } #endif } tcp_seq tcp_iss_seq = 0; /* tcp initial seq # */ /* * Get a new sequence value given a tcp control block */ tcp_seq tcp_new_iss(tp, len, addin) void *tp; u_long len; tcp_seq addin; { tcp_seq tcp_iss; /* * add randomness about this connection, but do not estimate * entropy from the timing, since the physical device driver would * have done that for us. */ #if NRND > 0 if (tp != NULL) rnd_add_data(NULL, tp, len, 0); #endif /* * randomize. */ #if NRND > 0 rnd_extract_data(&tcp_iss, sizeof(tcp_iss), RND_EXTRACT_ANY); #else tcp_iss = random(); #endif /* * If we were asked to add some amount to a known value, * we will take a random value obtained above, mask off the upper * bits, and add in the known value. We also add in a constant to * ensure that we are at least a certain distance from the original * value. * * This is used when an old connection is in timed wait * and we have a new one coming in, for instance. */ if (addin != 0) { #ifdef TCPISS_DEBUG printf("Random %08x, ", tcp_iss); #endif tcp_iss &= TCP_ISS_RANDOM_MASK; tcp_iss += addin + TCP_ISSINCR; #ifdef TCPISS_DEBUG printf("Old ISS %08x, ISS %08x\n", addin, tcp_iss); #endif } else { tcp_iss &= TCP_ISS_RANDOM_MASK; tcp_iss += tcp_iss_seq; tcp_iss_seq += TCP_ISSINCR; #ifdef TCPISS_DEBUG printf("ISS %08x\n", tcp_iss); #endif } if (tcp_compat_42) { /* * Limit it to the positive range for really old TCP * implementations. */ if (tcp_iss >= 0x80000000) tcp_iss &= 0x7fffffff; /* XXX */ } return tcp_iss; } /* * Determine the length of the TCP options for this connection. * * XXX: What do we do for SACK, when we add that? Just reserve * all of the space? Otherwise we can't exactly be incrementing * cwnd by an amount that varies depending on the amount we last * had to SACK! */ u_int tcp_optlen(tp) struct tcpcb *tp; { if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == (TF_REQ_TSTMP | TF_RCVD_TSTMP)) return TCPOLEN_TSTAMP_APPA; else return 0; }