/* $OpenBSD: tcp_subr.c,v 1.5 1996/05/15 09:32:01 mickey Exp $ */ /* $NetBSD: tcp_subr.c,v 1.22 1996/02/13 23:44:00 christos Exp $ */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993 * 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 8.1 (Berkeley) 6/10/93 */ #include #include #include #include #include #include #include #include #include #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; /* * Configure kernel with options "TCP_DO_RFC1323=0" to disable RFC1323 stuff. * This is a good idea over slow SLIP/PPP links, because the timestamp * pretty well destroys the VJ compression (any packet with a timestamp * different from the previous one can't be compressed), as well as adding * more overhead. * XXX And it should be a settable per route characteristic (with this just * used as the default). */ #ifndef TCP_DO_RFC1323 #define TCP_DO_RFC1323 1 #endif int tcp_do_rfc1323 = TCP_DO_RFC1323; #ifndef TCBHASHSIZE #define TCBHASHSIZE 128 #endif int tcbhashsize = TCBHASHSIZE; /* * Tcp initialization */ void tcp_init() { tcp_iss = 1; /* wrong */ in_pcbinit(&tcbtable, tcbhashsize); if (max_protohdr < sizeof(struct tcpiphdr)) max_protohdr = sizeof(struct tcpiphdr); if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) panic("tcp_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 mbuf *m; register struct tcpiphdr *n; if ((n = tp->t_template) == 0) { m = m_get(M_DONTWAIT, MT_HEADER); if (m == NULL) return (0); m->m_len = sizeof (struct tcpiphdr); n = mtod(m, struct tcpiphdr *); } 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. */ void 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; { register int tlen; int win = 0; struct route *ro = 0; if (tp) { win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); ro = &tp->t_inpcb->inp_route; } if (m == 0) { m = m_gethdr(M_DONTWAIT, MT_HEADER); if (m == NULL) return; #ifdef TCP_COMPAT_42 tlen = 1; #else tlen = 0; #endif 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 } ti->ti_len = htons((u_int16_t)(sizeof (struct tcphdr) + tlen)); tlen += sizeof (struct tcpiphdr); m->m_len = tlen; m->m_pkthdr.len = tlen; m->m_pkthdr.rcvif = (struct ifnet *) 0; bzero(ti->ti_x1, sizeof ti->ti_x1); ti->ti_seq = htonl(seq); ti->ti_ack = htonl(ack); ti->ti_x2 = 0; ti->ti_off = sizeof (struct tcphdr) >> 2; ti->ti_flags = flags; if (tp) ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale)); else ti->ti_win = htons((u_int16_t)win); 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; (void) ip_output(m, NULL, ro, 0, NULL); } /* * 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 = malloc(sizeof(*tp), M_PCB, M_NOWAIT); if (tp == NULL) return ((struct tcpcb *)0); bzero((char *) tp, sizeof(struct tcpcb)); LIST_INIT(&tp->segq); tp->t_maxseg = tcp_mssdflt; tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 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; { register struct ipqent *qe; 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) && satosin(rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { register u_long i = 0; if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { i = tp->t_srtt * (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 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_SCALE)); 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_maxseg / 2) / tp->t_maxseg; if (i < 2) i = 2; i *= (u_long)(tp->t_maxseg + 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 */ while ((qe = tp->segq.lh_first) != NULL) { LIST_REMOVE(qe, ipqe_q); m_freem(qe->ipqe_m); FREE(qe, M_IPQ); } if (tp->t_template) (void) m_free(dtom(tp->t_template)); free(tp, M_PCB); inp->inp_ppcb = 0; soisdisconnected(so); in_pcbdetach(inp); tcpstat.tcps_closed++; return ((struct tcpcb *)0); } void tcp_drain() { } /* * 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; 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_HOSTDEAD) ip = 0; else if (errno == 0) return NULL; if (ip) { th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); in_pcbnotify(&tcbtable, sa, th->th_dport, ip->ip_src, th->th_sport, errno, notify); } else in_pcbnotifyall(&tcbtable, sa, errno, notify); return NULL; } /* * When a source quench is received, close congestion window * to 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_maxseg; }