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[AROS.git] / workbench / network / stacks / AROSTCP / bsdsocket / netinet / tcp_subr.c

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 2006 Pavel Fedin
 *
 * 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
 * $Id$
 */

#include <sys/param.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 <sys/queue.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/in_var.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>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
#endif

#include <kern/kern_subr_protos.h>

/* patchable/settable parameters for tcp */
int     ip_defttl = 60;                           /* default time to live for TCP segs */
int     tcp_mssdflt = TCP_MSS;
int     tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
int     tcp_do_rfc1323 = 1;
int     tcp_do_rfc1644 = 1;
static  void tcp_cleartaocache(void);

extern u_char inetctlerrmap[];
extern struct in_addr zeroin_addr;

/*
 * Target size of TCP PCB hash table. Will be rounded down to a prime
 * number.
 */
#ifndef TCBHASHSIZE
#define TCBHASHSIZE     128
#endif

/*
 * Tcp initialization
 */
void
tcp_init()
{

        tcp_iss = 1;            /* wrong */
        tcp_ccgen = 1;
        tcp_cleartaocache();
        LIST_INIT(&tcb);
        tcbinfo.listhead = &tcb;
        tcbinfo.hashbase = phashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashsize);
        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_long);
                xchg(ti->ti_dport, ti->ti_sport, u_short);
#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;
        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_short) (win >> tp->rcv_scale));
        else
                ti->ti_win = htons((u_short)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;
#ifdef TCPDEBUG
        if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
                tcp_trace(TA_OUTPUT, 0, tp, ti, 0);
#endif
#ifdef ENABLE_MULTICAST
        (void) ip_output(m, NULL, ro, 0, NULL);
#else
        (void) ip_output(m, NULL, ro, 0);
#endif
}

/*
 * 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 = bsd_malloc(sizeof(*tp), M_PCB, M_NOWAIT);
        if (tp == NULL)
                return ((struct tcpcb *)0);
        bzero((char *) tp, sizeof(struct tcpcb));
        tp->t_segq = NULL;
        tp->t_maxseg = tp->t_maxopd = tcp_mssdflt;

        if (tcp_do_rfc1323)
                tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
        if (tcp_do_rfc1644)
                tp->t_flags |= TF_REQ_CC;
        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 << 2;
        tp->t_rttmin = TCPTV_MIN;
        TCPT_RANGESET(tp->t_rxtcur,
            ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
            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;
        register struct mbuf *q;
        register struct mbuf *nq;
#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) &&
            ((struct sockaddr_in *)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) != 0) && 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 */
        for (q = tp->t_segq; q; q = nq) {
                nq = q->m_nextpkt;
                tp->t_segq = nq;
                m_freem(q);
        }
        if (tp->t_template)
                (void) m_free(dtom(tp->t_template));
        bsd_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 (tp->t_state < TCPS_ESTABLISHED && 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, arg)
        int cmd;
        struct sockaddr *sa;
        void *arg;
{
        register struct ip *ip = arg;
        register struct tcphdr *th;
        void (*notify) __P((struct inpcb *, int)) = tcp_notify;

        if (cmd == PRC_QUENCH)
                notify = tcp_quench;
        else if (!PRC_IS_REDIRECT(cmd) &&
                 ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0))
                return;
        if (ip) {
                th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2));
                in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport,
                        cmd, notify);
        } else
                in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, 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;
}

/*
 * Look-up the routing entry to the peer of this inpcb.  If no route
 * is found and it cannot be allocated the return NULL.  This routine
 * is called by TCP routines that access the rmx structure and by tcp_mss
 * to get the interface MTU.
 */
struct rtentry *
tcp_rtlookup(inp)
        struct inpcb *inp;
{
        struct route *ro;
        struct rtentry *rt;

        ro = &inp->inp_route;
        rt = ro->ro_rt;
        if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
                /* No route yet, so try to acquire one */
                if (inp->inp_faddr.s_addr != INADDR_ANY) {
                        struct sockaddr_in *rodst_saddr = (struct sockaddr_in *)&ro->ro_dst;
                        ro->ro_dst.sa_family = AF_INET;
                        ro->ro_dst.sa_len = sizeof(ro->ro_dst);
                        rodst_saddr->sin_addr = inp->inp_faddr;
                        rtalloc(ro);
                        rt = ro->ro_rt;
                }
        }
        return rt;
}

/*
 * Return a pointer to the cached information about the remote host.
 * The cached information is stored in the protocol specific part of
 * the route metrics.
 */
struct rmxp_tao *
tcp_gettaocache(inp)
        struct inpcb *inp;
{
        struct rtentry *rt = tcp_rtlookup(inp);

        /* Make sure this is a host route and is up. */
        if (rt == NULL ||
            (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
                return NULL;

        return rmx_taop(rt->rt_rmx);
}

/*
 * Clear all the TAO cache entries, called from tcp_init.
 *
 * XXX
 * This routine is just an empty one, because we assume that the routing
 * routing tables are initialized at the same time when TCP, so there is
 * nothing in the cache left over.
 */
static void
tcp_cleartaocache(void)
{ }