initial import of NetBSD tree

1 files changed, 453 insertions, 0 deletions

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
new file mode 100644
index 00000000000..76f8c9d631b
--- /dev/null
+++ b/sys/netinet/tcp_subr.c
@@ -0,0 +1,453 @@
+/*	$NetBSD: tcp_subr.c,v 1.19 1995/06/12 06:48:54 mycroft 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 <sys/param.h>
+#include <sys/proc.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/socket.h>
+#include <sys/socketvar.h>
+#include <sys/protosw.h>
+#include <sys/errno.h>
+
+#include <net/route.h>
+#include <net/if.h>
+
+#include <netinet/in.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/in_pcb.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_icmp.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 <netinet/tcpip.h>
+
+/* patchable/settable parameters for tcp */
+int 	tcp_mssdflt = TCP_MSS;
+int 	tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
+int	tcp_do_rfc1323 = 1;
+
+extern	struct inpcb *tcp_last_inpcb;
+
+/*
+ * Tcp initialization
+ */
+void
+tcp_init()
+{
+
+	tcp_iss = 1;		/* wrong */
+	in_pcbinit(&tcbtable);
+	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 *);
+	}
+	n->ti_next = n->ti_prev = 0;
+	n->ti_x1 = 0;
+	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_short)(sizeof (struct tcphdr) + tlen));
+	tlen += sizeof (struct tcpiphdr);
+	m->m_len = tlen;
+	m->m_pkthdr.len = tlen;
+	m->m_pkthdr.rcvif = (struct ifnet *) 0;
+	ti->ti_next = ti->ti_prev = 0;
+	ti->ti_x1 = 0;
+	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));
+	tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp;
+	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 tcpiphdr *t;
+	struct inpcb *inp = tp->t_inpcb;
+	struct socket *so = inp->inp_socket;
+	register struct mbuf *m;
+#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;
+
+		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 */
+	t = tp->seg_next;
+	while (t != (struct tcpiphdr *)tp) {
+		t = (struct tcpiphdr *)t->ti_next;
+		m = REASS_MBUF((struct tcpiphdr *)t->ti_prev);
+		remque(t->ti_prev);
+		m_freem(m);
+	}
+	if (tp->t_template)
+		(void) m_free(dtom(tp->t_template));
+	free(tp, M_PCB);
+	inp->inp_ppcb = 0;
+	soisdisconnected(so);
+	/* clobber input pcb cache if we're closing the cached connection */
+	if (inp == tcp_last_inpcb)
+		tcp_last_inpcb = 0;
+	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, ip)
+	int cmd;
+	struct sockaddr *sa;
+	register struct ip *ip;
+{
+	register struct tcphdr *th;
+	extern struct in_addr zeroin_addr;
+	extern int inetctlerrmap[];
+	void (*notify) __P((struct inpcb *, int)) = tcp_notify;
+	int errno;
+
+	if ((unsigned)cmd >= PRC_NCMDS)
+		return;
+	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;
+	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);
+}
+
+/*
+ * 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;
+}