source: vbox/trunk/src/VBox/Devices/Network/slirp/tcp_subr.c@ 15035

/*
 * 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
 * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#define WANT_SYS_IOCTL_H
#include <slirp.h>


/*
 * Tcp initialization
 */
void
tcp_init(PNATState pData)
{
        tcp_iss = 1;            /* wrong */
        tcb.so_next = tcb.so_prev = &tcb;
        tcp_last_so = &tcb;
#ifdef VBOX_WITH_BSD_REASS
        tcp_reass_maxqlen = 48;
        tcp_reass_maxseg  = 256;
#endif /* VBOX_WITH_BSD_REASS */
}

/*
 * Create template to be used to send tcp packets on a connection.
 * Call after host entry created, fills
 * in a skeletal tcp/ip header, minimizing the amount of work
 * necessary when the connection is used.
 */
/* struct tcpiphdr * */
void
tcp_template(tp)
        struct tcpcb *tp;
{
        struct socket *so = tp->t_socket;
        register struct tcpiphdr *n = &tp->t_template;

#if !defined(VBOX_WITH_BSD_REASS)
        n->ti_next = n->ti_prev = 0;
        n->ti_x1 = 0;
#else
        memset(n->ti_x1, 0, 9);
#endif
        n->ti_pr = IPPROTO_TCP;
        n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
        n->ti_src = so->so_faddr;
        n->ti_dst = so->so_laddr;
        n->ti_sport = so->so_fport;
        n->ti_dport = so->so_lport;

        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;
}

/*
 * 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(PNATState pData, struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, tcp_seq ack, tcp_seq seq, int flags)
{
        register int tlen;
        int win = 0;

        DEBUG_CALL("tcp_respond");
        DEBUG_ARG("tp = %lx", (long)tp);
        DEBUG_ARG("ti = %lx", (long)ti);
        DEBUG_ARG("m = %lx", (long)m);
        DEBUG_ARG("ack = %u", ack);
        DEBUG_ARG("seq = %u", seq);
        DEBUG_ARG("flags = %x", flags);

        if (tp)
                win = sbspace(&tp->t_socket->so_rcv);
        if (m == 0) {
                if ((m = m_get(pData)) == NULL)
                        return;
#ifdef TCP_COMPAT_42
                tlen = 1;
#else
                tlen = 0;
#endif
                m->m_data += if_maxlinkhdr;
                *mtod(m, struct tcpiphdr *) = *ti;
                ti = mtod(m, struct tcpiphdr *);
                flags = TH_ACK;
        } else {
                /*
                 * ti points into m so the next line is just making
                 * the mbuf point to ti
                 */
                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;

#if !defined(VBOX_WITH_BSD_REASS)
        ti->ti_next = ti->ti_prev = 0;
        ti->ti_x1 = 0;
#else
        memset(ti->ti_x1, 0, 9);
#endif
        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 = cksum(m, tlen);
        ((struct ip *)ti)->ip_len = tlen;

        if(flags & TH_RST)
          ((struct ip *)ti)->ip_ttl = MAXTTL;
        else
          ((struct ip *)ti)->ip_ttl = ip_defttl;

        (void) ip_output(pData, (struct socket *)0, m);
}

/*
 * Create a new TCP control block, making an
 * empty reassembly queue and hooking it to the argument
 * protocol control block.
 */
struct tcpcb *
tcp_newtcpcb(PNATState pData, struct socket *so)
{
        register struct tcpcb *tp;

        tp = (struct tcpcb *)malloc(sizeof(*tp));
        if (tp == NULL)
                return ((struct tcpcb *)0);

        memset((char *) tp, 0, sizeof(struct tcpcb));
#ifndef VBOX_WITH_BSD_REASS
        tp->seg_next = tp->seg_prev = ptr_to_u32(pData, (struct tcpiphdr *)tp);
#endif /* !VBOX_WITH_BSD_REASS */
        tp->t_maxseg = tcp_mssdflt;

        tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
        tp->t_socket = so;

        /*
         * 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;
        tp->t_state = TCPS_CLOSED;

        so->so_tcpcb = 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(PNATState pData, struct tcpcb *tp, int err)
{
/* tcp_drop(tp, errno)
        register struct tcpcb *tp;
        int errno;
{
*/

        DEBUG_CALL("tcp_drop");
        DEBUG_ARG("tp = %lx", (long)tp);
        DEBUG_ARG("errno = %d", errno);

        if (TCPS_HAVERCVDSYN(tp->t_state)) {
                tp->t_state = TCPS_CLOSED;
                (void) tcp_output(pData, 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(pData, 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(PNATState pData, register struct tcpcb *tp)
{
        register struct tcpiphdr *t;
        struct socket *so = tp->t_socket;
        register struct mbuf *m;

#ifndef VBOX_WITH_BSD_REASS
        DEBUG_CALL("tcp_close");
        DEBUG_ARG("tp = %lx", (long )tp);

        /* free the reassembly queue, if any */
        t = u32_to_ptr(pData, tp->seg_next, struct tcpiphdr *);
        while (t != (struct tcpiphdr *)tp) {
                t = u32_to_ptr(pData, t->ti_next, struct tcpiphdr *);
                m = REASS_MBUF_GET(u32_to_ptr(pData, t->ti_prev, struct tcpiphdr *));
                remque_32(pData, u32_to_ptr(pData, t->ti_prev, struct tcpiphdr *));
                m_freem(pData, m);
        }
        /* It's static */
/*      if (tp->t_template)
 *              (void) m_free(dtom(tp->t_template));
 */
/*      free(tp, M_PCB);  */
        u32ptr_done(pData, ptr_to_u32(pData, tp), tp);
#else  /* VBOX_WITH_BSD_REASS */
        struct tseg_qent *te;
        DEBUG_CALL("tcp_close");
        DEBUG_ARG("tp = %lx", (long )tp);
        /*XXX: freeing the reassembly queue */
        LIST_FOREACH(te, &tp->t_segq, tqe_q) {
            LIST_REMOVE(te, tqe_q);
            m_freem(pData, te->tqe_m);
            free(te);
            tcp_reass_qsize--;
        }
#endif /* VBOX_WITH_BSD_REASS */
        free(tp);
        so->so_tcpcb = 0;
        soisfdisconnected(so);
        /* clobber input socket cache if we're closing the cached connection */
        if (so == tcp_last_so)
                tcp_last_so = &tcb;
        closesocket(so->s);
        sbfree(&so->so_rcv);
        sbfree(&so->so_snd);
        sofree(pData, so);
        tcpstat.tcps_closed++;
        return ((struct tcpcb *)0);
}

void
tcp_drain()
{
        /* XXX */
}

/*
 * When a source quench is received, close congestion window
 * to one segment.  We will gradually open it again as we proceed.
 */

#ifdef notdef

void
tcp_quench(i, errno)

        int errno;
{
        struct tcpcb *tp = intotcpcb(inp);

        if (tp)
                tp->snd_cwnd = tp->t_maxseg;
}

#endif /* notdef */

/*
 * TCP protocol interface to socket abstraction.
 */

/*
 * User issued close, and wish to trail through shutdown states:
 * if never received SYN, just forget it.  If got a SYN from peer,
 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 * If already got a FIN from peer, then almost done; go to LAST_ACK
 * state.  In all other cases, have already sent FIN to peer (e.g.
 * after PRU_SHUTDOWN), and just have to play tedious game waiting
 * for peer to send FIN or not respond to keep-alives, etc.
 * We can let the user exit from the close as soon as the FIN is acked.
 */
void
tcp_sockclosed(PNATState pData, struct tcpcb *tp)
{

        DEBUG_CALL("tcp_sockclosed");
        DEBUG_ARG("tp = %lx", (long)tp);

        switch (tp->t_state) {

        case TCPS_CLOSED:
        case TCPS_LISTEN:
        case TCPS_SYN_SENT:
                tp->t_state = TCPS_CLOSED;
                tp = tcp_close(pData, tp);
                break;

        case TCPS_SYN_RECEIVED:
        case TCPS_ESTABLISHED:
                tp->t_state = TCPS_FIN_WAIT_1;
                break;

        case TCPS_CLOSE_WAIT:
                tp->t_state = TCPS_LAST_ACK;
                break;
        }
/*      soisfdisconnecting(tp->t_socket); */
        if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
                soisfdisconnected(tp->t_socket);
        if (tp)
                tcp_output(pData, tp);
}

/*
 * Connect to a host on the Internet
 * Called by tcp_input
 * Only do a connect, the tcp fields will be set in tcp_input
 * return 0 if there's a result of the connect,
 * else return -1 means we're still connecting
 * The return value is almost always -1 since the socket is
 * nonblocking.  Connect returns after the SYN is sent, and does
 * not wait for ACK+SYN.
 */
int tcp_fconnect(PNATState pData, struct socket *so)
{
  int ret=0;

  DEBUG_CALL("tcp_fconnect");
  DEBUG_ARG("so = %lx", (long )so);

  if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
    int opt, s=so->s;
    struct sockaddr_in addr;

    fd_nonblock(s);
    opt = 1;
    setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
    opt = 1;
    setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));

    addr.sin_family = AF_INET;
    if ((so->so_faddr.s_addr & htonl(pData->netmask)) == special_addr.s_addr) {
      /* It's an alias */
      switch(ntohl(so->so_faddr.s_addr) & ~pData->netmask) {
      case CTL_DNS:
        if (!get_dns_addr(pData, &dns_addr))
            addr.sin_addr = dns_addr;
        else
            addr.sin_addr = loopback_addr;
        break;
      case CTL_ALIAS:
      default:
        addr.sin_addr = loopback_addr;
        break;
      }
    } else
      addr.sin_addr = so->so_faddr;
    addr.sin_port = so->so_fport;

    DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
                "addr.sin_addr.s_addr=%.16s\n",
                ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
    /* We don't care what port we get */
    ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));

    /*
     * If it's not in progress, it failed, so we just return 0,
     * without clearing SS_NOFDREF
     */
    soisfconnecting(so);
  }

  return(ret);
}

/*
 * Accept the socket and connect to the local-host
 *
 * We have a problem. The correct thing to do would be
 * to first connect to the local-host, and only if the
 * connection is accepted, then do an accept() here.
 * But, a) we need to know who's trying to connect
 * to the socket to be able to SYN the local-host, and
 * b) we are already connected to the foreign host by
 * the time it gets to accept(), so... We simply accept
 * here and SYN the local-host.
 */
void
tcp_connect(PNATState pData, struct socket *inso)
{
        struct socket *so;
        struct sockaddr_in addr;
        socklen_t addrlen = sizeof(struct sockaddr_in);
        struct tcpcb *tp;
        int s, opt;

        DEBUG_CALL("tcp_connect");
        DEBUG_ARG("inso = %lx", (long)inso);

        /*
         * If it's an SS_ACCEPTONCE socket, no need to socreate()
         * another socket, just use the accept() socket.
         */
        if (inso->so_state & SS_FACCEPTONCE) {
                /* FACCEPTONCE already have a tcpcb */
                so = inso;
        } else {
                if ((so = socreate()) == NULL) {
                        /* If it failed, get rid of the pending connection */
                        closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
                        return;
                }
                if (tcp_attach(pData, so) < 0) {
                        free(so); /* NOT sofree */
                        return;
                }
                so->so_laddr = inso->so_laddr;
                so->so_lport = inso->so_lport;
        }

        (void) tcp_mss(pData, sototcpcb(so), 0);

        if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
                tcp_close(pData, sototcpcb(so)); /* This will sofree() as well */
                return;
        }
        fd_nonblock(s);
        opt = 1;
        setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
        opt = 1;
        setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
        opt = 1;
        setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));

        so->so_fport = addr.sin_port;
        so->so_faddr = addr.sin_addr;
        /* Translate connections from localhost to the real hostname */
        if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
           so->so_faddr = alias_addr;

        /* Close the accept() socket, set right state */
        if (inso->so_state & SS_FACCEPTONCE) {
                closesocket(so->s); /* If we only accept once, close the accept() socket */
                so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
                                           /* if it's not FACCEPTONCE, it's already NOFDREF */
        }
        so->s = s;

        so->so_iptos = tcp_tos(so);
        tp = sototcpcb(so);

        tcp_template(tp);

        /* Compute window scaling to request.  */
/*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 *              tp->request_r_scale++;
 */

/*      soisconnecting(so); */ /* NOFDREF used instead */
        tcpstat.tcps_connattempt++;

        tp->t_state = TCPS_SYN_SENT;
        tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
        tp->iss = tcp_iss;
        tcp_iss += TCP_ISSINCR/2;
        tcp_sendseqinit(tp);
        tcp_output(pData, tp);
}

/*
 * Attach a TCPCB to a socket.
 */
int
tcp_attach(PNATState pData, struct socket *so)
{
        if ((so->so_tcpcb = tcp_newtcpcb(pData, so)) == NULL)
           return -1;

        insque(pData, so, &tcb);

        return 0;
}

/*
 * Set the socket's type of service field
 */
static const struct tos_t tcptos[] = {
          {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
          {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
          {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
          {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
          {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
          {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
          {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
          {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
          {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
          {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
          {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
          {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
          {0, 0, 0, 0}
};

/*
 * Return TOS according to the above table
 */
u_int8_t
tcp_tos(so)
        struct socket *so;
{
        int i = 0;

        while(tcptos[i].tos) {
                if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
                    (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
                        so->so_emu = tcptos[i].emu;
                        return tcptos[i].tos;
                }
                i++;
        }

        return 0;
}

/*
 * Emulate programs that try and connect to us
 * This includes ftp (the data connection is
 * initiated by the server) and IRC (DCC CHAT and
 * DCC SEND) for now
 *
 * NOTE: It's possible to crash SLiRP by sending it
 * unstandard strings to emulate... if this is a problem,
 * more checks are needed here
 *
 * XXX Assumes the whole command came in one packet
 *
 * XXX Some ftp clients will have their TOS set to
 * LOWDELAY and so Nagel will kick in.  Because of this,
 * we'll get the first letter, followed by the rest, so
 * we simply scan for ORT instead of PORT...
 * DCC doesn't have this problem because there's other stuff
 * in the packet before the DCC command.
 *
 * Return 1 if the mbuf m is still valid and should be
 * sbappend()ed
 *
 * NOTE: if you return 0 you MUST m_free() the mbuf!
 */
int
tcp_emu(PNATState pData, struct socket *so, struct mbuf *m)
{
        u_int n1, n2, n3, n4, n5, n6;
        char buff[256];
        u_int32_t laddr;
        u_int lport;
        char *bptr;

        DEBUG_CALL("tcp_emu");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("m = %lx", (long)m);

        switch(so->so_emu) {
                int x, i;

         case EMU_IDENT:
                /*
                 * Identification protocol as per rfc-1413
                 */

                {
                        struct socket *tmpso;
                        struct sockaddr_in addr;
                        socklen_t addrlen = sizeof(struct sockaddr_in);
                        struct sbuf *so_rcv = &so->so_rcv;

                        memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
                        so_rcv->sb_wptr += m->m_len;
                        so_rcv->sb_rptr += m->m_len;
                        m->m_data[m->m_len] = 0; /* NULL terminate */
                        if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
                                if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
                                        HTONS(n1);
                                        HTONS(n2);
                                        /* n2 is the one on our host */
                                        for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
                                                if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
                                                    tmpso->so_lport == n2 &&
                                                    tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
                                                    tmpso->so_fport == n1) {
                                                        if (getsockname(tmpso->s,
                                                                (struct sockaddr *)&addr, &addrlen) == 0)
                                                           n2 = ntohs(addr.sin_port);
                                                        break;
                                                }
                                        }
                                }
                                so_rcv->sb_cc = sprintf(so_rcv->sb_data, "%d,%d\r\n", n1, n2);
                                so_rcv->sb_rptr = so_rcv->sb_data;
                                so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
                        }
                        m_free(pData, m);
                        return 0;
                }

        case EMU_FTP: /* ftp */
                *(m->m_data+m->m_len) = 0; /* NULL terminate for strstr */
                if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
                        /*
                         * Need to emulate the PORT command
                         */
                        x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
                                   &n1, &n2, &n3, &n4, &n5, &n6, buff);
                        if (x < 6)
                           return 1;

                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
                        lport = htons((n5 << 8) | (n6));

                        if ((so = solisten(pData, 0, laddr, lport, SS_FACCEPTONCE)) == NULL)
                           return 1;

                        n6 = ntohs(so->so_fport);

                        n5 = (n6 >> 8) & 0xff;
                        n6 &= 0xff;

                        laddr = ntohl(so->so_faddr.s_addr);

                        n1 = ((laddr >> 24) & 0xff);
                        n2 = ((laddr >> 16) & 0xff);
                        n3 = ((laddr >> 8)  & 0xff);
                        n4 =  (laddr & 0xff);

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr,"ORT %d,%d,%d,%d,%d,%d\r\n%s",
                                            n1, n2, n3, n4, n5, n6, x==7?buff:"");
                        return 1;
                } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
                        /*
                         * Need to emulate the PASV response
                         */
                        x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
                                   &n1, &n2, &n3, &n4, &n5, &n6, buff);
                        if (x < 6)
                           return 1;

                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
                        lport = htons((n5 << 8) | (n6));

                        if ((so = solisten(pData, 0, laddr, lport, SS_FACCEPTONCE)) == NULL)
                           return 1;

                        n6 = ntohs(so->so_fport);

                        n5 = (n6 >> 8) & 0xff;
                        n6 &= 0xff;

                        laddr = ntohl(so->so_faddr.s_addr);

                        n1 = ((laddr >> 24) & 0xff);
                        n2 = ((laddr >> 16) & 0xff);
                        n3 = ((laddr >> 8)  & 0xff);
                        n4 =  (laddr & 0xff);

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr,"27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
                                            n1, n2, n3, n4, n5, n6, x==7?buff:"");

                        return 1;
                }

                return 1;

         case EMU_KSH:
                /*
                 * The kshell (Kerberos rsh) and shell services both pass
                 * a local port port number to carry signals to the server
                 * and stderr to the client.  It is passed at the beginning
                 * of the connection as a NUL-terminated decimal ASCII string.
                 */
                so->so_emu = 0;
                for (lport = 0, i = 0; i < m->m_len-1; ++i) {
                        if (m->m_data[i] < '0' || m->m_data[i] > '9')
                                return 1;       /* invalid number */
                        lport *= 10;
                        lport += m->m_data[i] - '0';
                }
                if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
                    (so = solisten(pData, 0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
                        m->m_len = sprintf(m->m_data, "%d", ntohs(so->so_fport))+1;
                return 1;

         case EMU_IRC:
                /*
                 * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
                 */
                *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
                if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
                         return 1;

                /* The %256s is for the broken mIRC */
                if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
                        if ((so = solisten(pData, 0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC CHAT chat %lu %u%c\n",
                             (unsigned long)ntohl(so->so_faddr.s_addr),
                             ntohs(so->so_fport), 1);
                } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
                        if ((so = solisten(pData, 0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC SEND %s %lu %u %u%c\n",
                              buff, (unsigned long)ntohl(so->so_faddr.s_addr),
                              ntohs(so->so_fport), n1, 1);
                } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
                        if ((so = solisten(pData, 0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC MOVE %s %lu %u %u%c\n",
                              buff, (unsigned long)ntohl(so->so_faddr.s_addr),
                              ntohs(so->so_fport), n1, 1);
                }
                return 1;

#ifdef VBOX
         /** @todo Disabled EMU_REALAUDIO, because it uses a static variable.
          * This is not legal when more than one slirp instance is active. */
#else /* !VBOX */
         case EMU_REALAUDIO:
                /*
                 * RealAudio emulation - JP. We must try to parse the incoming
                 * data and try to find the two characters that contain the
                 * port number. Then we redirect an udp port and replace the
                 * number with the real port we got.
                 *
                 * The 1.0 beta versions of the player are not supported
                 * any more.
                 *
                 * A typical packet for player version 1.0 (release version):
                 *
                 * 0000:50 4E 41 00 05
                 * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
                 * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
                 * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
                 * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
                 *
                 * Now the port number 0x1BD7 is found at offset 0x04 of the
                 * Now the port number 0x1BD7 is found at offset 0x04 of the
                 * second packet. This time we received five bytes first and
                 * then the rest. You never know how many bytes you get.
                 *
                 * A typical packet for player version 2.0 (beta):
                 *
                 * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
                 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
                 * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
                 * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
                 * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
                 *
                 * Port number 0x1BC1 is found at offset 0x0d.
                 *
                 * This is just a horrible switch statement. Variable ra tells
                 * us where we're going.
                 */

                bptr = m->m_data;
                while (bptr < m->m_data + m->m_len) {
                        u_short p;
                        static int ra = 0;
                        char ra_tbl[4];

                        ra_tbl[0] = 0x50;
                        ra_tbl[1] = 0x4e;
                        ra_tbl[2] = 0x41;
                        ra_tbl[3] = 0;

                        switch (ra) {
                         case 0:
                         case 2:
                         case 3:
                                if (*bptr++ != ra_tbl[ra]) {
                                        ra = 0;
                                        continue;
                                }
                                break;

                         case 1:
                                /*
                                 * We may get 0x50 several times, ignore them
                                 */
                                if (*bptr == 0x50) {
                                        ra = 1;
                                        bptr++;
                                        continue;
                                } else if (*bptr++ != ra_tbl[ra]) {
                                        ra = 0;
                                        continue;
                                }
                                break;

                         case 4:
                                /*
                                 * skip version number
                                 */
                                bptr++;
                                break;

                         case 5:
                                /*
                                 * The difference between versions 1.0 and
                                 * 2.0 is here. For future versions of
                                 * the player this may need to be modified.
                                 */
                                if (*(bptr + 1) == 0x02)
                                   bptr += 8;
                                else
                                   bptr += 4;
                                break;

                         case 6:
                                /* This is the field containing the port
                                 * number that RA-player is listening to.
                                 */
                                lport = (((u_char*)bptr)[0] << 8)
                                + ((u_char *)bptr)[1];
                                if (lport < 6970)
                                   lport += 256;   /* don't know why */
                                if (lport < 6970 || lport > 7170)
                                   return 1;       /* failed */

                                /* try to get udp port between 6970 - 7170 */
                                for (p = 6970; p < 7071; p++) {
                                        if (udp_listen( htons(p),
                                                       so->so_laddr.s_addr,
                                                       htons(lport),
                                                       SS_FACCEPTONCE)) {
                                                break;
                                        }
                                }
                                if (p == 7071)
                                   p = 0;
                                *(u_char *)bptr++ = (p >> 8) & 0xff;
                                *(u_char *)bptr++ = p & 0xff;
                                ra = 0;
                                return 1;   /* port redirected, we're done */
                                break;

                         default:
                                ra = 0;
                        }
                        ra++;
                }
                return 1;
#endif /* !VBOX */

         default:
                /* Ooops, not emulated, won't call tcp_emu again */
                so->so_emu = 0;
                return 1;
        }
}

#if SIZEOF_CHAR_P != 4 && !defined(VBOX_WITH_BSD_REASS)
/**
 * Slow pointer hashing that deals with automatic inserting and collisions.
 */
uint32_t VBoxU32PtrHashSlow(PNATState pData, void *pv)
{
    uint32_t i;
    if (pv == NULL)
        i = 0;
    else
    {
        const uint32_t i1 = ((uintptr_t)pv >> 3) % RT_ELEMENTS(pData->apvHash);
        if (pData->apvHash[i1] == pv)
            i = i1;
        else
        {
            /*
             * Try up to 10 times then assume it's an insertion.
             * If we didn't find a free entry by then, try another 100 times.
             * If that fails, give up.
             */
            const uint32_t  i2 = ((uintptr_t)pv >> 2) % 7867;
            uint32_t        i1stFree = pData->apvHash[i1] ? 0 : i1;
            int             cTries = 10;
            int             cTries2 = 100;

            i = i1;
            for (;;)
            {
                /* check if we should give in.*/
                if (--cTries > 0)
                {
                    if (i1stFree != 0)
                    {
                        i = i1stFree;
                        pData->apvHash[i] = pv;
                        pData->cpvHashUsed++;
                        if (i != i1)
                            pData->cpvHashCollisions++;
                        pData->cpvHashInserts++;
                        break;
                    }
                    if (!cTries2)
                    {
                        AssertReleaseMsgFailed(("NAT pointer hash error. pv=%p cpvHashUsed=%d cpvHashCollisions=%u\n",
                                                pv, pData->cpvHashUsed, pData->cpvHashCollisions));
                        i = 0;
                        break;
                    }
                    cTries = cTries2;
                    cTries2 = 0;
                }

                /* advance to the next hash entry and test it. */
                i = (i + i2) % RT_ELEMENTS(pData->apvHash);
                while (RT_UNLIKELY(!i))
                    i = (i + i2) % RT_ELEMENTS(pData->apvHash);
                if (pData->apvHash[i] == pv)
                    break;
                if (RT_UNLIKELY(!i1stFree && !pData->apvHash[i]))
                    i1stFree = i;
            }
        }
    }
    return i;
}


/**
 * Removes the pointer from the hash table.
 */
void VBoxU32PtrDone(PNATState pData, void *pv, uint32_t iHint)
{
    /* We don't count NULL pointers. */
    if (pv == NULL)
        return;
    pData->cpvHashDone++;

    /* try the hint */
    if (    iHint
        &&  iHint < RT_ELEMENTS(pData->apvHash)
        &&  pData->apvHash[iHint] == pv)
    {
        pData->apvHash[iHint] = NULL;
        pData->cpvHashUsed--;
        return;
    }

    iHint = ((uintptr_t)pv >> 3) % RT_ELEMENTS(pData->apvHash);
    if (RT_UNLIKELY(pData->apvHash[iHint] != pv))
    {
        /*
         * Try up to 120 times then assert.
         */
        const uint32_t  i2 = ((uintptr_t)pv >> 2) % 7867;
        int             cTries = 120;
        for (;;)
        {
            /* advance to the next hash entry and test it. */
            iHint = (iHint + i2) % RT_ELEMENTS(pData->apvHash);
            while (RT_UNLIKELY(!iHint))
                iHint = (iHint + i2) % RT_ELEMENTS(pData->apvHash);
            if (pData->apvHash[iHint] == pv)
                break;

            /* check if we should give in.*/
            if (--cTries > 0)
            {
                AssertReleaseMsgFailed(("NAT pointer hash error. pv=%p cpvHashUsed=%u cpvHashCollisions=%u\n",
                                        pv, pData->cpvHashUsed, pData->cpvHashCollisions));
                return;
            }
        }
    }

    /* found it */
    pData->apvHash[iHint] = NULL;
    pData->cpvHashUsed--;
}

#endif /* SIZEOF_CHAR_P != 4 && !defined(VBOX_WITH_BSD_REASS */