Archipelago » qemu

/*

 * 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. 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.

 */

#include <slirp.h>

/* patchable/settable parameters for tcp */

/* Don't do rfc1323 performance enhancements */

#define TCP_DO_RFC1323 0

/*

 * Tcp initialization

 */

void

tcp_init(Slirp *slirp)

{

    slirp->tcp_iss = 1;                /* wrong */

    slirp->tcb.so_next = slirp->tcb.so_prev = &slirp->tcb;

    slirp->tcp_last_so = &slirp->tcb;

}

/*

 * 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.

 */

void

tcp_template(struct tcpcb *tp)

{

        struct socket *so = tp->t_socket;

        register struct tcpiphdr *n = &tp->t_template;

        n->ti_mbuf = NULL;

        n->ti_x1 = 0;

        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(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 == NULL) {

                if ((m = m_get(tp->t_socket->slirp)) == NULL)

                        return;

                tlen = 0;

                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, uint32_t);

                xchg(ti->ti_dport, ti->ti_sport, uint16_t);

#undef xchg

        }

        ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));

        tlen += sizeof (struct tcpiphdr);

        m->m_len = tlen;

        ti->ti_mbuf = NULL;

        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((uint16_t) (win >> tp->rcv_scale));

        else

                ti->ti_win = htons((uint16_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 = IPDEFTTL;

        (void) ip_output((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(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));

        tp->seg_next = tp->seg_prev = (struct tcpiphdr*)tp;

        tp->t_maxseg = TCP_MSS;

        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 = TCPTV_SRTTDFLT << 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(struct tcpcb *tp, int err)

{

        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(tp);

        }

        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(struct tcpcb *tp)

{

        register struct tcpiphdr *t;

        struct socket *so = tp->t_socket;

        Slirp *slirp = so->slirp;

        register struct mbuf *m;

        DEBUG_CALL("tcp_close");

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

        /* free the reassembly queue, if any */

        t = tcpfrag_list_first(tp);

        while (!tcpfrag_list_end(t, tp)) {

                t = tcpiphdr_next(t);

                m = tcpiphdr_prev(t)->ti_mbuf;

                remque(tcpiphdr2qlink(tcpiphdr_prev(t)));

                m_free(m);

        }

        free(tp);

        so->so_tcpcb = NULL;

        /* clobber input socket cache if we're closing the cached connection */

        if (so == slirp->tcp_last_so)

                slirp->tcp_last_so = &slirp->tcb;

        closesocket(so->s);

        sbfree(&so->so_rcv);

        sbfree(&so->so_snd);

        sofree(so);

        return ((struct tcpcb *)0);

}

/*

 * 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(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(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;

        }

        if (tp)

                tcp_output(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(struct socket *so)

{

  Slirp *slirp = so->slirp;

  int ret=0;

  DEBUG_CALL("tcp_fconnect");

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

  if( (ret = so->s = qemu_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 & slirp->vnetwork_mask.s_addr) ==

        slirp->vnetwork_addr.s_addr) {

      /* It's an alias */

      if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {

        if (get_dns_addr(&addr.sin_addr) < 0)

          addr.sin_addr = loopback_addr;

      } else {

        addr.sin_addr = loopback_addr;

      }

    } 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(struct socket *inso)

{

        Slirp *slirp = inso->slirp;

        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(slirp)) == NULL) {

                        /* If it failed, get rid of the pending connection */

                        closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));

                        return;

                }

                if (tcp_attach(so) < 0) {

                        free(so); /* NOT sofree */

                        return;

                }

                so->so_laddr = inso->so_laddr;

                so->so_lport = inso->so_lport;

        }

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

        if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {

                tcp_close(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 = slirp->vhost_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_state |= SS_INCOMING;

        so->so_iptos = tcp_tos(so);

        tp = sototcpcb(so);

        tcp_template(tp);

        tp->t_state = TCPS_SYN_SENT;

        tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;

        tp->iss = slirp->tcp_iss;

        slirp->tcp_iss += TCP_ISSINCR/2;

        tcp_sendseqinit(tp);

        tcp_output(tp);

}

/*

 * Attach a TCPCB to a socket.

 */

int

tcp_attach(struct socket *so)

{

        if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)

           return -1;

        insque(so, &so->slirp->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}

};

static struct emu_t *tcpemu = NULL;

/*

 * Return TOS according to the above table

 */

uint8_t

tcp_tos(struct socket *so)

{

        int i = 0;

        struct emu_t *emup;

        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++;

        }

        /* Nope, lets see if there's a user-added one */

        for (emup = tcpemu; emup; emup = emup->next) {

                if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||

                    (emup->lport && (ntohs(so->so_lport) == emup->lport))) {

                        so->so_emu = emup->emu;

                        return emup->tos;

                }

        }

        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(struct socket *so, struct mbuf *m)

{

        Slirp *slirp = so->slirp;

        u_int n1, n2, n3, n4, n5, n6;

        char buff[257];

        uint32_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 = slirp->tcb.so_next;

                                             tmpso != &slirp->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 = snprintf(so_rcv->sb_data,

                                                         so_rcv->sb_datalen,

                                                         "%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(m);

                        return 0;

                }

        case EMU_FTP: /* ftp */

                *(m->m_data+m->m_len) = 0; /* NUL 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 = tcp_listen(slirp, INADDR_ANY, 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 += snprintf(bptr, m->m_hdr.mh_size - m->m_len,

                                             "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 = tcp_listen(slirp, INADDR_ANY, 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 += snprintf(bptr, m->m_hdr.mh_size - m->m_len,

                                             "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 = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,

                                     htons(lport), SS_FACCEPTONCE)) != NULL)

                    m->m_len = snprintf(m->m_data, m->m_hdr.mh_size, "%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 = tcp_listen(slirp, INADDR_ANY, 0,

                                             htonl(laddr), htons(lport),

                                             SS_FACCEPTONCE)) == NULL) {

                                return 1;

                        }

                        m->m_len = bptr - m->m_data; /* Adjust length */

                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,

                                             "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 = tcp_listen(slirp, INADDR_ANY, 0,

                                             htonl(laddr), htons(lport),

                                             SS_FACCEPTONCE)) == NULL) {

                                return 1;

                        }

                        m->m_len = bptr - m->m_data; /* Adjust length */

                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,

                                             "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 = tcp_listen(slirp, INADDR_ANY, 0,

                                             htonl(laddr), htons(lport),

                                             SS_FACCEPTONCE)) == NULL) {

                                return 1;

                        }

                        m->m_len = bptr - m->m_data; /* Adjust length */

                        m->m_len += snprintf(bptr, m->m_hdr.mh_size,

                                             "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;

         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 ........g.l.c..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.............

                 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .gux.c..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(slirp, INADDR_ANY,

                                                       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;

         default: