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. 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>

/* patchable/settable parameters for tcp */

int         tcp_mssdflt = TCP_MSS;

int         tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;

int        tcp_do_rfc1323 = 0;        /* Don't do rfc1323 performance enhancements */

int        tcp_rcvspace;        /* You may want to change this */

int        tcp_sndspace;        /* Keep small if you have an error prone link */

/*

 * Tcp initialization

 */

void

tcp_init()

{

        tcp_iss = 1;                /* wrong */

        tcb.so_next = tcb.so_prev = &tcb;

        /* tcp_rcvspace = our Window we advertise to the remote */

        tcp_rcvspace = TCP_RCVSPACE;

        tcp_sndspace = TCP_SNDSPACE;

        /* Make sure tcp_sndspace is at least 2*MSS */

        if (tcp_sndspace < 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr)))

                tcp_sndspace = 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr));

}

/*

 * 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;

        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 = 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(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;

        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()) == 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;

        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 = 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((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(so)

        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 = (tcpiphdrp_32)tp;

        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(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(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 socket *so = tp->t_socket;

        register struct mbuf *m;

        DEBUG_CALL("tcp_close");

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

        /* free the reassembly queue, if any */

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

        while (t != (struct tcpiphdr *)tp) {

                t = (struct tcpiphdr *)t->ti_next;

                m = (struct mbuf *) REASS_MBUF((struct tcpiphdr *)t->ti_prev);

                remque_32((struct tcpiphdr *) t->ti_prev);

                m_freem(m);

        }

        /* It's static */

/*        if (tp->t_template)

 *                (void) m_free(dtom(tp->t_template));

 */

/*        free(tp, M_PCB);  */

        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(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(tp)

        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;

        }

/*        soisfdisconnecting(tp->t_socket); */

        if (tp && tp->t_state >= TCPS_FIN_WAIT_2)

                soisfdisconnected(tp->t_socket);

        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(so)

     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(0xffffff00)) == special_addr.s_addr) {

      /* It's an alias */

      switch(ntohl(so->so_faddr.s_addr) & 0xff) {

      case CTL_DNS:

        addr.sin_addr = dns_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(inso)

        struct socket *inso;

{

        struct socket *so;

        struct sockaddr_in addr;

        int 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(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 = 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(tp);

}

/*

 * Attach a TCPCB to a socket.

 */

int

tcp_attach(so)

        struct socket *so;

{

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

           return -1;

        insque(so, &tcb);

        return 0;

}

/*

 * Set the socket's type of service field

 */

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}

};

struct emu_t *tcpemu = 0;

/*

 * Return TOS according to the above table

 */

u_int8_t

tcp_tos(so)

        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;

}

int do_echo = -1;

/*

 * 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(so, m)

        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;

                        int 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, "%d%*[ ,]%d", &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(m);

                        return 0;

                }

#if 0

         case EMU_RLOGIN:

                /*

                 * Rlogin emulation

                 * First we accumulate all the initial option negotiation,

                 * then fork_exec() rlogin according to the  options

                 */

                {

                        int i, i2, n;

                        char *ptr;

                        char args[100];

                        char term[100];

                        struct sbuf *so_snd = &so->so_snd;

                        struct sbuf *so_rcv = &so->so_rcv;

                        /* First check if they have a priveladged port, or too much data has arrived */

                        if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||

                            (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {

                                memcpy(so_snd->sb_wptr, "Permission denied\n", 18);

                                so_snd->sb_wptr += 18;

                                so_snd->sb_cc += 18;

                                tcp_sockclosed(sototcpcb(so));

                                m_free(m);

                                return 0;

                        }

                        /* Append the current data */

                        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_free(m);

                        /*

                         * Check if we have all the initial options,

                         * and build argument list to rlogin while we're here

                         */

                        n = 0;

                        ptr = so_rcv->sb_data;

                        args[0] = 0;

                        term[0] = 0;

                        while (ptr < so_rcv->sb_wptr) {

                                if (*ptr++ == 0) {

                                        n++;

                                        if (n == 2) {

                                                sprintf(args, "rlogin -l %s %s",

                                                        ptr, inet_ntoa(so->so_faddr));

                                        } else if (n == 3) {

                                                i2 = so_rcv->sb_wptr - ptr;

                                                for (i = 0; i < i2; i++) {

                                                        if (ptr[i] == '/') {

                                                                ptr[i] = 0;

#ifdef HAVE_SETENV

                                                                sprintf(term, "%s", ptr);

#else

                                                                sprintf(term, "TERM=%s", ptr);

#endif

                                                                ptr[i] = '/';

                                                                break;

                                                        }

                                                }

                                        }

                                }

                        }

                        if (n != 4)

                           return 0;

                        /* We have it, set our term variable and fork_exec() */

#ifdef HAVE_SETENV

                        setenv("TERM", term, 1);

#else

                        putenv(term);

#endif

                        fork_exec(so, args, 2);

                        term[0] = 0;

                        so->so_emu = 0;

                        /* And finally, send the client a 0 character */

                        so_snd->sb_wptr[0] = 0;

                        so_snd->sb_wptr++;

                        so_snd->sb_cc++;

                        return 0;

                }

         case EMU_RSH:

                /*

                 * rsh emulation

                 * First we accumulate all the initial option negotiation,

                 * then rsh_exec() rsh according to the  options

                 */

                {

                        int  n;

                        char *ptr;

                        char *user;

                        char *args;

                        struct sbuf *so_snd = &so->so_snd;

                        struct sbuf *so_rcv = &so->so_rcv;

                        /* First check if they have a priveladged port, or too much data has arrived */

                        if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||

                            (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {

                                memcpy(so_snd->sb_wptr, "Permission denied\n", 18);

                                so_snd->sb_wptr += 18;

                                so_snd->sb_cc += 18;

                                tcp_sockclosed(sototcpcb(so));

                                m_free(m);

                                return 0;

                        }

                        /* Append the current data */

                        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_free(m);

                        /*

                         * Check if we have all the initial options,

                         * and build argument list to rlogin while we're here

                         */

                        n = 0;

                        ptr = so_rcv->sb_data;

                        user="";

                        args="";

                        if (so->extra==NULL) {

                                struct socket *ns;

                                struct tcpcb* tp;

                                int port=atoi(ptr);

                                if (port <= 0) return 0;

                if (port > 1023 || port < 512) {

                  memcpy(so_snd->sb_wptr, "Permission denied\n", 18);

                  so_snd->sb_wptr += 18;

                  so_snd->sb_cc += 18;

                  tcp_sockclosed(sototcpcb(so));

                  return 0;

                }

                                if ((ns=socreate()) == NULL)

                  return 0;

                                if (tcp_attach(ns)<0) {

                  free(ns);

                  return 0;

                                }

                                ns->so_laddr=so->so_laddr;

                                ns->so_lport=htons(port);

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

                                ns->so_faddr=so->so_faddr;

                                ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */

                                if (ns->so_faddr.s_addr == 0 || 

                                        ns->so_faddr.s_addr == loopback_addr.s_addr)

                  ns->so_faddr = alias_addr;

                                ns->so_iptos = tcp_tos(ns);

                                tp = sototcpcb(ns);

                                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++;

                                 */

                /*soisfconnecting(ns);*/

                                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(tp);

                                so->extra=ns;

                        }

                        while (ptr < so_rcv->sb_wptr) {

              if (*ptr++ == 0) {

                n++;

                if (n == 2) {

                  user=ptr;

                } else if (n == 3) {

                  args=ptr;

                }

              }

                        }

                        if (n != 4)

              return 0;

                        rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);

                        so->so_emu = 0;

                        so->extra=NULL;