slirp/tcp_subr.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)tcp_subr.c  8.1 (Berkeley) 6/10/93
  34  * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
  35  */
  36
  37 /*
  38  * Changes and additions relating to SLiRP
  39  * Copyright (c) 1995 Danny Gasparovski.
  40  *
  41  * Please read the file COPYRIGHT for the
  42  * terms and conditions of the copyright.
  43  */
  44
  45 #define WANT_SYS_IOCTL_H
  46 #include <slirp.h>
  47
  48 /* patchable/settable parameters for tcp */
  49 /* Don't do rfc1323 performance enhancements */
  50 #define TCP_DO_RFC1323 0
  51
  52 /*
  53  * Tcp initialization
  54  */
  55 void
  56 tcp_init()
  57 {
  58         tcp_iss = 1;            /* wrong */
  59         tcb.so_next = tcb.so_prev = &tcb;
  60 }
  61
  62 /*
  63  * Create template to be used to send tcp packets on a connection.
  64  * Call after host entry created, fills
  65  * in a skeletal tcp/ip header, minimizing the amount of work
  66  * necessary when the connection is used.
  67  */
  68 /* struct tcpiphdr * */
  69 void
  70 tcp_template(tp)
  71         struct tcpcb *tp;
  72 {
  73         struct socket *so = tp->t_socket;
  74         register struct tcpiphdr *n = &tp->t_template;
  75
  76         n->ti_next = n->ti_prev = 0;
  77         n->ti_x1 = 0;
  78         n->ti_pr = IPPROTO_TCP;
  79         n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
  80         n->ti_src = so->so_faddr;
  81         n->ti_dst = so->so_laddr;
  82         n->ti_sport = so->so_fport;
  83         n->ti_dport = so->so_lport;
  84
  85         n->ti_seq = 0;
  86         n->ti_ack = 0;
  87         n->ti_x2 = 0;
  88         n->ti_off = 5;
  89         n->ti_flags = 0;
  90         n->ti_win = 0;
  91         n->ti_sum = 0;
  92         n->ti_urp = 0;
  93 }
  94
  95 /*
  96  * Send a single message to the TCP at address specified by
  97  * the given TCP/IP header.  If m == 0, then we make a copy
  98  * of the tcpiphdr at ti and send directly to the addressed host.
  99  * This is used to force keep alive messages out using the TCP
 100  * template for a connection tp->t_template.  If flags are given
 101  * then we send a message back to the TCP which originated the
 102  * segment ti, and discard the mbuf containing it and any other
 103  * attached mbufs.
 104  *
 105  * In any case the ack and sequence number of the transmitted
 106  * segment are as specified by the parameters.
 107  */
 108 void
 109 tcp_respond(tp, ti, m, ack, seq, flags)
 110         struct tcpcb *tp;
 111         register struct tcpiphdr *ti;
 112         register struct mbuf *m;
 113         tcp_seq ack, seq;
 114         int flags;
 115 {
 116         register int tlen;
 117         int win = 0;
 118
 119         DEBUG_CALL("tcp_respond");
 120         DEBUG_ARG("tp = %lx", (long)tp);
 121         DEBUG_ARG("ti = %lx", (long)ti);
 122         DEBUG_ARG("m = %lx", (long)m);
 123         DEBUG_ARG("ack = %u", ack);
 124         DEBUG_ARG("seq = %u", seq);
 125         DEBUG_ARG("flags = %x", flags);
 126
 127         if (tp)
 128                 win = sbspace(&tp->t_socket->so_rcv);
 129         if (m == 0) {
 130                 if ((m = m_get()) == NULL)
 131                         return;
 132 #ifdef TCP_COMPAT_42
 133                 tlen = 1;
 134 #else
 135                 tlen = 0;
 136 #endif
 137                 m->m_data += IF_MAXLINKHDR;
 138                 *mtod(m, struct tcpiphdr *) = *ti;
 139                 ti = mtod(m, struct tcpiphdr *);
 140                 flags = TH_ACK;
 141         } else {
 142                 /*
 143                  * ti points into m so the next line is just making
 144                  * the mbuf point to ti
 145                  */
 146                 m->m_data = (caddr_t)ti;
 147
 148                 m->m_len = sizeof (struct tcpiphdr);
 149                 tlen = 0;
 150 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 151                 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
 152                 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
 153 #undef xchg
 154         }
 155         ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 156         tlen += sizeof (struct tcpiphdr);
 157         m->m_len = tlen;
 158
 159         ti->ti_next = ti->ti_prev = 0;
 160         ti->ti_x1 = 0;
 161         ti->ti_seq = htonl(seq);
 162         ti->ti_ack = htonl(ack);
 163         ti->ti_x2 = 0;
 164         ti->ti_off = sizeof (struct tcphdr) >> 2;
 165         ti->ti_flags = flags;
 166         if (tp)
 167                 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
 168         else
 169                 ti->ti_win = htons((u_int16_t)win);
 170         ti->ti_urp = 0;
 171         ti->ti_sum = 0;
 172         ti->ti_sum = cksum(m, tlen);
 173         ((struct ip *)ti)->ip_len = tlen;
 174
 175         if(flags & TH_RST)
 176           ((struct ip *)ti)->ip_ttl = MAXTTL;
 177         else
 178           ((struct ip *)ti)->ip_ttl = IPDEFTTL;
 179
 180         (void) ip_output((struct socket *)0, m);
 181 }
 182
 183 /*
 184  * Create a new TCP control block, making an
 185  * empty reassembly queue and hooking it to the argument
 186  * protocol control block.
 187  */
 188 struct tcpcb *
 189 tcp_newtcpcb(so)
 190         struct socket *so;
 191 {
 192         register struct tcpcb *tp;
 193
 194         tp = (struct tcpcb *)malloc(sizeof(*tp));
 195         if (tp == NULL)
 196                 return ((struct tcpcb *)0);
 197
 198         memset((char *) tp, 0, sizeof(struct tcpcb));
 199         tp->seg_next = tp->seg_prev = (tcpiphdrp_32)tp;
 200         tp->t_maxseg = TCP_MSS;
 201
 202         tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 203         tp->t_socket = so;
 204
 205         /*
 206          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 207          * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 208          * reasonable initial retransmit time.
 209          */
 210         tp->t_srtt = TCPTV_SRTTBASE;
 211         tp->t_rttvar = TCPTV_SRTTDFLT << 2;
 212         tp->t_rttmin = TCPTV_MIN;
 213
 214         TCPT_RANGESET(tp->t_rxtcur,
 215             ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 216             TCPTV_MIN, TCPTV_REXMTMAX);
 217
 218         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 219         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 220         tp->t_state = TCPS_CLOSED;
 221
 222         so->so_tcpcb = tp;
 223
 224         return (tp);
 225 }
 226
 227 /*
 228  * Drop a TCP connection, reporting
 229  * the specified error.  If connection is synchronized,
 230  * then send a RST to peer.
 231  */
 232 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 233 {
 234 /* tcp_drop(tp, errno)
 235         register struct tcpcb *tp;
 236         int errno;
 237 {
 238 */
 239
 240         DEBUG_CALL("tcp_drop");
 241         DEBUG_ARG("tp = %lx", (long)tp);
 242         DEBUG_ARG("errno = %d", errno);
 243
 244         if (TCPS_HAVERCVDSYN(tp->t_state)) {
 245                 tp->t_state = TCPS_CLOSED;
 246                 (void) tcp_output(tp);
 247                 STAT(tcpstat.tcps_drops++);
 248         } else
 249                 STAT(tcpstat.tcps_conndrops++);
 250 /*      if (errno == ETIMEDOUT && tp->t_softerror)
 251  *              errno = tp->t_softerror;
 252  */
 253 /*      so->so_error = errno; */
 254         return (tcp_close(tp));
 255 }
 256
 257 /*
 258  * Close a TCP control block:
 259  *      discard all space held by the tcp
 260  *      discard internet protocol block
 261  *      wake up any sleepers
 262  */
 263 struct tcpcb *
 264 tcp_close(tp)
 265         register struct tcpcb *tp;
 266 {
 267         register struct tcpiphdr *t;
 268         struct socket *so = tp->t_socket;
 269         register struct mbuf *m;
 270
 271         DEBUG_CALL("tcp_close");
 272         DEBUG_ARG("tp = %lx", (long )tp);
 273
 274         /* free the reassembly queue, if any */
 275         t = (struct tcpiphdr *) tp->seg_next;
 276         while (t != (struct tcpiphdr *)tp) {
 277                 t = (struct tcpiphdr *)t->ti_next;
 278                 m = (struct mbuf *) REASS_MBUF((struct tcpiphdr *)t->ti_prev);
 279                 remque_32((struct tcpiphdr *) t->ti_prev);
 280                 m_freem(m);
 281         }
 282         /* It's static */
 283 /*      if (tp->t_template)
 284  *              (void) m_free(dtom(tp->t_template));
 285  */
 286 /*      free(tp, M_PCB);  */
 287         free(tp);
 288         so->so_tcpcb = 0;
 289         soisfdisconnected(so);
 290         /* clobber input socket cache if we're closing the cached connection */
 291         if (so == tcp_last_so)
 292                 tcp_last_so = &tcb;
 293         closesocket(so->s);
 294         sbfree(&so->so_rcv);
 295         sbfree(&so->so_snd);
 296         sofree(so);
 297         STAT(tcpstat.tcps_closed++);
 298         return ((struct tcpcb *)0);
 299 }
 300
 301 #ifdef notdef
 302 void
 303 tcp_drain()
 304 {
 305         /* XXX */
 306 }
 307
 308 /*
 309  * When a source quench is received, close congestion window
 310  * to one segment.  We will gradually open it again as we proceed.
 311  */
 312 void
 313 tcp_quench(i, errno)
 314
 315         int errno;
 316 {
 317         struct tcpcb *tp = intotcpcb(inp);
 318
 319         if (tp)
 320                 tp->snd_cwnd = tp->t_maxseg;
 321 }
 322
 323 #endif /* notdef */
 324
 325 /*
 326  * TCP protocol interface to socket abstraction.
 327  */
 328
 329 /*
 330  * User issued close, and wish to trail through shutdown states:
 331  * if never received SYN, just forget it.  If got a SYN from peer,
 332  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 333  * If already got a FIN from peer, then almost done; go to LAST_ACK
 334  * state.  In all other cases, have already sent FIN to peer (e.g.
 335  * after PRU_SHUTDOWN), and just have to play tedious game waiting
 336  * for peer to send FIN or not respond to keep-alives, etc.
 337  * We can let the user exit from the close as soon as the FIN is acked.
 338  */
 339 void
 340 tcp_sockclosed(tp)
 341         struct tcpcb *tp;
 342 {
 343
 344         DEBUG_CALL("tcp_sockclosed");
 345         DEBUG_ARG("tp = %lx", (long)tp);
 346
 347         switch (tp->t_state) {
 348
 349         case TCPS_CLOSED:
 350         case TCPS_LISTEN:
 351         case TCPS_SYN_SENT:
 352                 tp->t_state = TCPS_CLOSED;
 353                 tp = tcp_close(tp);
 354                 break;
 355
 356         case TCPS_SYN_RECEIVED:
 357         case TCPS_ESTABLISHED:
 358                 tp->t_state = TCPS_FIN_WAIT_1;
 359                 break;
 360
 361         case TCPS_CLOSE_WAIT:
 362                 tp->t_state = TCPS_LAST_ACK;
 363                 break;
 364         }
 365 /*      soisfdisconnecting(tp->t_socket); */
 366         if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
 367                 soisfdisconnected(tp->t_socket);
 368         if (tp)
 369                 tcp_output(tp);
 370 }
 371
 372 /*
 373  * Connect to a host on the Internet
 374  * Called by tcp_input
 375  * Only do a connect, the tcp fields will be set in tcp_input
 376  * return 0 if there's a result of the connect,
 377  * else return -1 means we're still connecting
 378  * The return value is almost always -1 since the socket is
 379  * nonblocking.  Connect returns after the SYN is sent, and does
 380  * not wait for ACK+SYN.
 381  */
 382 int tcp_fconnect(so)
 383      struct socket *so;
 384 {
 385   int ret=0;
 386
 387   DEBUG_CALL("tcp_fconnect");
 388   DEBUG_ARG("so = %lx", (long )so);
 389
 390   if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
 391     int opt, s=so->s;
 392     struct sockaddr_in addr;
 393
 394     fd_nonblock(s);
 395     opt = 1;
 396     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
 397     opt = 1;
 398     setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
 399
 400     addr.sin_family = AF_INET;
 401     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 402       /* It's an alias */
 403       switch(ntohl(so->so_faddr.s_addr) & 0xff) {
 404       case CTL_DNS:
 405         addr.sin_addr = dns_addr;
 406         break;
 407       case CTL_ALIAS:
 408       default:
 409         addr.sin_addr = loopback_addr;
 410         break;
 411       }
 412     } else
 413       addr.sin_addr = so->so_faddr;
 414     addr.sin_port = so->so_fport;
 415
 416     DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
 417                 "addr.sin_addr.s_addr=%.16s\n",
 418                 ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
 419     /* We don't care what port we get */
 420     ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
 421
 422     /*
 423      * If it's not in progress, it failed, so we just return 0,
 424      * without clearing SS_NOFDREF
 425      */
 426     soisfconnecting(so);
 427   }
 428
 429   return(ret);
 430 }
 431
 432 /*
 433  * Accept the socket and connect to the local-host
 434  *
 435  * We have a problem. The correct thing to do would be
 436  * to first connect to the local-host, and only if the
 437  * connection is accepted, then do an accept() here.
 438  * But, a) we need to know who's trying to connect
 439  * to the socket to be able to SYN the local-host, and
 440  * b) we are already connected to the foreign host by
 441  * the time it gets to accept(), so... We simply accept
 442  * here and SYN the local-host.
 443  */
 444 void
 445 tcp_connect(inso)
 446         struct socket *inso;
 447 {
 448         struct socket *so;
 449         struct sockaddr_in addr;
 450         int addrlen = sizeof(struct sockaddr_in);
 451         struct tcpcb *tp;
 452         int s, opt;
 453
 454         DEBUG_CALL("tcp_connect");
 455         DEBUG_ARG("inso = %lx", (long)inso);
 456
 457         /*
 458          * If it's an SS_ACCEPTONCE socket, no need to socreate()
 459          * another socket, just use the accept() socket.
 460          */
 461         if (inso->so_state & SS_FACCEPTONCE) {
 462                 /* FACCEPTONCE already have a tcpcb */
 463                 so = inso;
 464         } else {
 465                 if ((so = socreate()) == NULL) {
 466                         /* If it failed, get rid of the pending connection */
 467                         closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
 468                         return;
 469                 }
 470                 if (tcp_attach(so) < 0) {
 471                         free(so); /* NOT sofree */
 472                         return;
 473                 }
 474                 so->so_laddr = inso->so_laddr;
 475                 so->so_lport = inso->so_lport;
 476         }
 477
 478         (void) tcp_mss(sototcpcb(so), 0);
 479
 480         if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
 481                 tcp_close(sototcpcb(so)); /* This will sofree() as well */
 482                 return;
 483         }
 484         fd_nonblock(s);
 485         opt = 1;
 486         setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 487         opt = 1;
 488         setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
 489         opt = 1;
 490         setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));
 491
 492         so->so_fport = addr.sin_port;
 493         so->so_faddr = addr.sin_addr;
 494         /* Translate connections from localhost to the real hostname */
 495         if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
 496            so->so_faddr = alias_addr;
 497
 498         /* Close the accept() socket, set right state */
 499         if (inso->so_state & SS_FACCEPTONCE) {
 500                 closesocket(so->s); /* If we only accept once, close the accept() socket */
 501                 so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
 502                                            /* if it's not FACCEPTONCE, it's already NOFDREF */
 503         }
 504         so->s = s;
 505
 506         so->so_iptos = tcp_tos(so);
 507         tp = sototcpcb(so);
 508
 509         tcp_template(tp);
 510
 511         /* Compute window scaling to request.  */
 512 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 513  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 514  *              tp->request_r_scale++;
 515  */
 516
 517 /*      soisconnecting(so); */ /* NOFDREF used instead */
 518         STAT(tcpstat.tcps_connattempt++);
 519
 520         tp->t_state = TCPS_SYN_SENT;
 521         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 522         tp->iss = tcp_iss;
 523         tcp_iss += TCP_ISSINCR/2;
 524         tcp_sendseqinit(tp);
 525         tcp_output(tp);
 526 }
 527
 528 /*
 529  * Attach a TCPCB to a socket.
 530  */
 531 int
 532 tcp_attach(so)
 533         struct socket *so;
 534 {
 535         if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 536            return -1;
 537
 538         insque(so, &tcb);
 539
 540         return 0;
 541 }
 542
 543 /*
 544  * Set the socket's type of service field
 545  */
 546 static const struct tos_t tcptos[] = {
 547           {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 548           {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 549           {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 550           {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 551           {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 552           {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 553           {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 554           {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 555           {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 556           {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 557           {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 558           {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 559           {0, 0, 0, 0}
 560 };
 561
 562 #ifdef CONFIG_QEMU
 563 static
 564 #endif
 565 struct emu_t *tcpemu = 0;
 566
 567 /*
 568  * Return TOS according to the above table
 569  */
 570 u_int8_t
 571 tcp_tos(so)
 572         struct socket *so;
 573 {
 574         int i = 0;
 575         struct emu_t *emup;
 576
 577         while(tcptos[i].tos) {
 578                 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 579                     (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 580                         so->so_emu = tcptos[i].emu;
 581                         return tcptos[i].tos;
 582                 }
 583                 i++;
 584         }
 585
 586         /* Nope, lets see if there's a user-added one */
 587         for (emup = tcpemu; emup; emup = emup->next) {
 588                 if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 589                     (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 590                         so->so_emu = emup->emu;
 591                         return emup->tos;
 592                 }
 593         }
 594
 595         return 0;
 596 }
 597
 598 #if 0
 599 int do_echo = -1;
 600 #endif
 601
 602 /*
 603  * Emulate programs that try and connect to us
 604  * This includes ftp (the data connection is
 605  * initiated by the server) and IRC (DCC CHAT and
 606  * DCC SEND) for now
 607  *
 608  * NOTE: It's possible to crash SLiRP by sending it
 609  * unstandard strings to emulate... if this is a problem,
 610  * more checks are needed here
 611  *
 612  * XXX Assumes the whole command came in one packet
 613  *
 614  * XXX Some ftp clients will have their TOS set to
 615  * LOWDELAY and so Nagel will kick in.  Because of this,
 616  * we'll get the first letter, followed by the rest, so
 617  * we simply scan for ORT instead of PORT...
 618  * DCC doesn't have this problem because there's other stuff
 619  * in the packet before the DCC command.
 620  *
 621  * Return 1 if the mbuf m is still valid and should be
 622  * sbappend()ed
 623  *
 624  * NOTE: if you return 0 you MUST m_free() the mbuf!
 625  */
 626 int
 627 tcp_emu(so, m)
 628         struct socket *so;
 629         struct mbuf *m;
 630 {
 631         u_int n1, n2, n3, n4, n5, n6;
 632         char buff[256];
 633         u_int32_t laddr;
 634         u_int lport;
 635         char *bptr;
 636
 637         DEBUG_CALL("tcp_emu");
 638         DEBUG_ARG("so = %lx", (long)so);
 639         DEBUG_ARG("m = %lx", (long)m);
 640
 641         switch(so->so_emu) {
 642                 int x, i;
 643
 644          case EMU_IDENT:
 645                 /*
 646                  * Identification protocol as per rfc-1413
 647                  */
 648
 649                 {
 650                         struct socket *tmpso;
 651                         struct sockaddr_in addr;
 652                         int addrlen = sizeof(struct sockaddr_in);
 653                         struct sbuf *so_rcv = &so->so_rcv;
 654
 655                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 656                         so_rcv->sb_wptr += m->m_len;
 657                         so_rcv->sb_rptr += m->m_len;
 658                         m->m_data[m->m_len] = 0; /* NULL terminate */
 659                         if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 660                                 if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
 661                                         HTONS(n1);
 662                                         HTONS(n2);
 663                                         /* n2 is the one on our host */
 664                                         for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
 665                                                 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 666                                                     tmpso->so_lport == n2 &&
 667                                                     tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 668                                                     tmpso->so_fport == n1) {
 669                                                         if (getsockname(tmpso->s,
 670                                                                 (struct sockaddr *)&addr, &addrlen) == 0)
 671                                                            n2 = ntohs(addr.sin_port);
 672                                                         break;
 673                                                 }
 674                                         }
 675                                 }
 676                                 so_rcv->sb_cc = sprintf(so_rcv->sb_data, "%d,%d\r\n", n1, n2);
 677                                 so_rcv->sb_rptr = so_rcv->sb_data;
 678                                 so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 679                         }
 680                         m_free(m);
 681                         return 0;
 682                 }
 683
 684 #if 0
 685          case EMU_RLOGIN:
 686                 /*
 687                  * Rlogin emulation
 688                  * First we accumulate all the initial option negotiation,
 689                  * then fork_exec() rlogin according to the  options
 690                  */
 691                 {
 692                         int i, i2, n;
 693                         char *ptr;
 694                         char args[100];
 695                         char term[100];
 696                         struct sbuf *so_snd = &so->so_snd;
 697                         struct sbuf *so_rcv = &so->so_rcv;
 698
 699                         /* First check if they have a priveladged port, or too much data has arrived */
 700                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 701                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 702                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 703                                 so_snd->sb_wptr += 18;
 704                                 so_snd->sb_cc += 18;
 705                                 tcp_sockclosed(sototcpcb(so));
 706                                 m_free(m);
 707                                 return 0;
 708                         }
 709
 710                         /* Append the current data */
 711                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 712                         so_rcv->sb_wptr += m->m_len;
 713                         so_rcv->sb_rptr += m->m_len;
 714                         m_free(m);
 715
 716                         /*
 717                          * Check if we have all the initial options,
 718                          * and build argument list to rlogin while we're here
 719                          */
 720                         n = 0;
 721                         ptr = so_rcv->sb_data;
 722                         args[0] = 0;
 723                         term[0] = 0;
 724                         while (ptr < so_rcv->sb_wptr) {
 725                                 if (*ptr++ == 0) {
 726                                         n++;
 727                                         if (n == 2) {
 728                                                 sprintf(args, "rlogin -l %s %s",
 729                                                         ptr, inet_ntoa(so->so_faddr));
 730                                         } else if (n == 3) {
 731                                                 i2 = so_rcv->sb_wptr - ptr;
 732                                                 for (i = 0; i < i2; i++) {
 733                                                         if (ptr[i] == '/') {
 734                                                                 ptr[i] = 0;
 735 #ifdef HAVE_SETENV
 736                                                                 sprintf(term, "%s", ptr);
 737 #else
 738                                                                 sprintf(term, "TERM=%s", ptr);
 739 #endif
 740                                                                 ptr[i] = '/';
 741                                                                 break;
 742                                                         }
 743                                                 }
 744                                         }
 745                                 }
 746                         }
 747
 748                         if (n != 4)
 749                            return 0;
 750
 751                         /* We have it, set our term variable and fork_exec() */
 752 #ifdef HAVE_SETENV
 753                         setenv("TERM", term, 1);
 754 #else
 755                         putenv(term);
 756 #endif
 757                         fork_exec(so, args, 2);
 758                         term[0] = 0;
 759                         so->so_emu = 0;
 760
 761                         /* And finally, send the client a 0 character */
 762                         so_snd->sb_wptr[0] = 0;
 763                         so_snd->sb_wptr++;
 764                         so_snd->sb_cc++;
 765
 766                         return 0;
 767                 }
 768
 769          case EMU_RSH:
 770                 /*
 771                  * rsh emulation
 772                  * First we accumulate all the initial option negotiation,
 773                  * then rsh_exec() rsh according to the  options
 774                  */
 775                 {
 776                         int  n;
 777                         char *ptr;
 778                         char *user;
 779                         char *args;
 780                         struct sbuf *so_snd = &so->so_snd;
 781                         struct sbuf *so_rcv = &so->so_rcv;
 782
 783                         /* First check if they have a priveladged port, or too much data has arrived */
 784                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 785                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 786                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 787                                 so_snd->sb_wptr += 18;
 788                                 so_snd->sb_cc += 18;
 789                                 tcp_sockclosed(sototcpcb(so));
 790                                 m_free(m);
 791                                 return 0;
 792                         }
 793
 794                         /* Append the current data */
 795                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 796                         so_rcv->sb_wptr += m->m_len;
 797                         so_rcv->sb_rptr += m->m_len;
 798                         m_free(m);
 799
 800                         /*
 801                          * Check if we have all the initial options,
 802                          * and build argument list to rlogin while we're here
 803                          */
 804                         n = 0;
 805                         ptr = so_rcv->sb_data;
 806                         user="";
 807                         args="";
 808                         if (so->extra==NULL) {
 809                                 struct socket *ns;
 810                                 struct tcpcb* tp;
 811                                 int port=atoi(ptr);
 812                                 if (port <= 0) return 0;
 813                 if (port > 1023 || port < 512) {
 814                   memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 815                   so_snd->sb_wptr += 18;
 816                   so_snd->sb_cc += 18;
 817                   tcp_sockclosed(sototcpcb(so));
 818                   return 0;
 819                 }
 820                                 if ((ns=socreate()) == NULL)
 821                   return 0;
 822                                 if (tcp_attach(ns)<0) {
 823                   free(ns);
 824                   return 0;
 825                                 }
 826
 827                                 ns->so_laddr=so->so_laddr;
 828                                 ns->so_lport=htons(port);
 829
 830                                 (void) tcp_mss(sototcpcb(ns), 0);
 831
 832                                 ns->so_faddr=so->so_faddr;
 833                                 ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */
 834
 835                                 if (ns->so_faddr.s_addr == 0 ||
 836                                         ns->so_faddr.s_addr == loopback_addr.s_addr)
 837                   ns->so_faddr = alias_addr;
 838
 839                                 ns->so_iptos = tcp_tos(ns);
 840                                 tp = sototcpcb(ns);
 841
 842                                 tcp_template(tp);
 843
 844                                 /* Compute window scaling to request.  */
 845                                 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 846                                  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 847                                  *              tp->request_r_scale++;
 848                                  */
 849
 850                 /*soisfconnecting(ns);*/
 851
 852                                 STAT(tcpstat.tcps_connattempt++);
 853
 854                                 tp->t_state = TCPS_SYN_SENT;
 855                                 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 856                                 tp->iss = tcp_iss;
 857                                 tcp_iss += TCP_ISSINCR/2;
 858                                 tcp_sendseqinit(tp);
 859                                 tcp_output(tp);
 860                                 so->extra=ns;
 861                         }
 862                         while (ptr < so_rcv->sb_wptr) {
 863               if (*ptr++ == 0) {
 864                 n++;
 865                 if (n == 2) {
 866                   user=ptr;
 867                 } else if (n == 3) {
 868                   args=ptr;
 869                 }
 870               }
 871                         }
 872
 873                         if (n != 4)
 874               return 0;
 875
 876                         rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
 877                         so->so_emu = 0;
 878                         so->extra=NULL;
 879
 880                         /* And finally, send the client a 0 character */
 881                         so_snd->sb_wptr[0] = 0;
 882                         so_snd->sb_wptr++;
 883                         so_snd->sb_cc++;
 884
 885                         return 0;
 886                 }
 887
 888          case EMU_CTL:
 889                 {
 890                         int num;
 891                         struct sbuf *so_snd = &so->so_snd;
 892                         struct sbuf *so_rcv = &so->so_rcv;
 893
 894                         /*
 895                          * If there is binary data here, we save it in so->so_m
 896                          */
 897                         if (!so->so_m) {
 898                           int rxlen;
 899                           char *rxdata;
 900                           rxdata=mtod(m, char *);
 901                           for (rxlen=m->m_len; rxlen; rxlen--) {
 902                             if (*rxdata++ & 0x80) {
 903                               so->so_m = m;
 904                               return 0;
 905                             }
 906                           }
 907                         } /* if(so->so_m==NULL) */
 908
 909                         /*
 910                          * Append the line
 911                          */
 912                         sbappendsb(so_rcv, m);
 913
 914                         /* To avoid going over the edge of the buffer, we reset it */
 915                         if (so_snd->sb_cc == 0)
 916                            so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;
 917
 918                         /*
 919                          * A bit of a hack:
 920                          * If the first packet we get here is 1 byte long, then it
 921                          * was done in telnet character mode, therefore we must echo
 922                          * the characters as they come.  Otherwise, we echo nothing,
 923                          * because in linemode, the line is already echoed
 924                          * XXX two or more control connections won't work
 925                          */
 926                         if (do_echo == -1) {
 927                                 if (m->m_len == 1) do_echo = 1;
 928                                 else do_echo = 0;
 929                         }
 930                         if (do_echo) {
 931                           sbappendsb(so_snd, m);
 932                           m_free(m);
 933                           tcp_output(sototcpcb(so)); /* XXX */
 934                         } else
 935                           m_free(m);
 936
 937                         num = 0;
 938                         while (num < so->so_rcv.sb_cc) {
 939                                 if (*(so->so_rcv.sb_rptr + num) == '\n' ||
 940                                     *(so->so_rcv.sb_rptr + num) == '\r') {
 941                                         int n;
 942
 943                                         *(so_rcv->sb_rptr + num) = 0;
 944                                         if (ctl_password && !ctl_password_ok) {
 945                                                 /* Need a password */
 946                                                 if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
 947                                                         if (strcmp(buff, ctl_password) == 0) {
 948                                                                 ctl_password_ok = 1;
 949                                                                 n = sprintf(so_snd->sb_wptr,
 950                                                                             "Password OK.\r\n");
 951                                                                 goto do_prompt;
 952                                                         }
 953                                                 }
 954                                                 n = sprintf(so_snd->sb_wptr,
 955                                          "Error: Password required, log on with \"pass PASSWORD\"\r\n");
 956                                                 goto do_prompt;
 957                                         }
 958                                         cfg_quitting = 0;
 959                                         n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
 960                                         if (!cfg_quitting) {
 961                                                 /* Register the printed data */
 962 do_prompt:
 963                                                 so_snd->sb_cc += n;
 964                                                 so_snd->sb_wptr += n;
 965                                                 /* Add prompt */
 966                                                 n = sprintf(so_snd->sb_wptr, "Slirp> ");
 967                                                 so_snd->sb_cc += n;
 968                                                 so_snd->sb_wptr += n;
 969                                         }
 970                                         /* Drop so_rcv data */
 971                                         so_rcv->sb_cc = 0;
 972                                         so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
 973                                         tcp_output(sototcpcb(so)); /* Send the reply */
 974                                 }
 975                                 num++;
 976                         }
 977                         return 0;
 978                 }
 979 #endif
 980         case EMU_FTP: /* ftp */
 981                 *(m->m_data+m->m_len) = 0; /* NULL terminate for strstr */
 982                 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 983                         /*
 984                          * Need to emulate the PORT command
 985                          */
 986                         x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
 987                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 988                         if (x < 6)
 989                            return 1;
 990
 991                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 992                         lport = htons((n5 << 8) | (n6));
 993
 994                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
 995                            return 1;
 996
 997                         n6 = ntohs(so->so_fport);
 998
 999                         n5 = (n6 >> 8) & 0xff;
1000                         n6 &= 0xff;
1001
1002                         laddr = ntohl(so->so_faddr.s_addr);
1003
1004                         n1 = ((laddr >> 24) & 0xff);
1005                         n2 = ((laddr >> 16) & 0xff);
1006                         n3 = ((laddr >> 8)  & 0xff);
1007                         n4 =  (laddr & 0xff);
1008
1009                         m->m_len = bptr - m->m_data; /* Adjust length */
1010                         m->m_len += sprintf(bptr,"ORT %d,%d,%d,%d,%d,%d\r\n%s",
1011                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
1012                         return 1;
1013                 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
1014                         /*
1015                          * Need to emulate the PASV response
1016                          */
1017                         x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
1018                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
1019                         if (x < 6)
1020                            return 1;
1021
1022                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
1023                         lport = htons((n5 << 8) | (n6));
1024
1025                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
1026                            return 1;
1027
1028                         n6 = ntohs(so->so_fport);
1029
1030                         n5 = (n6 >> 8) & 0xff;
1031                         n6 &= 0xff;
1032
1033                         laddr = ntohl(so->so_faddr.s_addr);
1034
1035                         n1 = ((laddr >> 24) & 0xff);
1036                         n2 = ((laddr >> 16) & 0xff);
1037                         n3 = ((laddr >> 8)  & 0xff);
1038                         n4 =  (laddr & 0xff);
1039
1040                         m->m_len = bptr - m->m_data; /* Adjust length */
1041                         m->m_len += sprintf(bptr,"27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
1042                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
1043
1044                         return 1;
1045                 }
1046
1047                 return 1;
1048
1049          case EMU_KSH:
1050                 /*
1051                  * The kshell (Kerberos rsh) and shell services both pass
1052                  * a local port port number to carry signals to the server
1053                  * and stderr to the client.  It is passed at the beginning
1054                  * of the connection as a NUL-terminated decimal ASCII string.
1055                  */
1056                 so->so_emu = 0;
1057                 for (lport = 0, i = 0; i < m->m_len-1; ++i) {
1058                         if (m->m_data[i] < '0' || m->m_data[i] > '9')
1059                                 return 1;       /* invalid number */
1060                         lport *= 10;
1061                         lport += m->m_data[i] - '0';
1062                 }
1063                 if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
1064                     (so = solisten(0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
1065                         m->m_len = sprintf(m->m_data, "%d", ntohs(so->so_fport))+1;
1066                 return 1;
1067
1068          case EMU_IRC:
1069                 /*
1070                  * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
1071                  */
1072                 *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
1073                 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
1074                          return 1;
1075
1076                 /* The %256s is for the broken mIRC */
1077                 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
1078                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1079                                 return 1;
1080
1081                         m->m_len = bptr - m->m_data; /* Adjust length */
1082                         m->m_len += sprintf(bptr, "DCC CHAT chat %lu %u%c\n",
1083                              (unsigned long)ntohl(so->so_faddr.s_addr),
1084                              ntohs(so->so_fport), 1);
1085                 } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1086                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1087                                 return 1;
1088
1089                         m->m_len = bptr - m->m_data; /* Adjust length */
1090                         m->m_len += sprintf(bptr, "DCC SEND %s %lu %u %u%c\n",
1091                               buff, (unsigned long)ntohl(so->so_faddr.s_addr),
1092                               ntohs(so->so_fport), n1, 1);
1093                 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1094                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1095                                 return 1;
1096
1097                         m->m_len = bptr - m->m_data; /* Adjust length */
1098                         m->m_len += sprintf(bptr, "DCC MOVE %s %lu %u %u%c\n",
1099                               buff, (unsigned long)ntohl(so->so_faddr.s_addr),
1100                               ntohs(so->so_fport), n1, 1);
1101                 }
1102                 return 1;
1103
1104          case EMU_REALAUDIO:
1105                 /*
1106                  * RealAudio emulation - JP. We must try to parse the incoming
1107                  * data and try to find the two characters that contain the
1108                  * port number. Then we redirect an udp port and replace the
1109                  * number with the real port we got.
1110                  *
1111                  * The 1.0 beta versions of the player are not supported
1112                  * any more.
1113                  *
1114                  * A typical packet for player version 1.0 (release version):
1115                  *
1116                  * 0000:50 4E 41 00 05
1117                  * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
1118                  * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
1119                  * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
1120                  * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
1121                  *
1122                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1123                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1124                  * second packet. This time we received five bytes first and
1125                  * then the rest. You never know how many bytes you get.
1126                  *
1127                  * A typical packet for player version 2.0 (beta):
1128                  *
1129                  * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
1130                  * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
1131                  * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
1132                  * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
1133                  * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
1134                  *
1135                  * Port number 0x1BC1 is found at offset 0x0d.
1136                  *
1137                  * This is just a horrible switch statement. Variable ra tells
1138                  * us where we're going.
1139                  */
1140
1141                 bptr = m->m_data;
1142                 while (bptr < m->m_data + m->m_len) {
1143                         u_short p;
1144                         static int ra = 0;
1145                         char ra_tbl[4];
1146
1147                         ra_tbl[0] = 0x50;
1148                         ra_tbl[1] = 0x4e;
1149                         ra_tbl[2] = 0x41;
1150                         ra_tbl[3] = 0;
1151
1152                         switch (ra) {
1153                          case 0:
1154                          case 2:
1155                          case 3:
1156                                 if (*bptr++ != ra_tbl[ra]) {
1157                                         ra = 0;
1158                                         continue;
1159                                 }
1160                                 break;
1161
1162                          case 1:
1163                                 /*
1164                                  * We may get 0x50 several times, ignore them
1165                                  */
1166                                 if (*bptr == 0x50) {
1167                                         ra = 1;
1168                                         bptr++;
1169                                         continue;
1170                                 } else if (*bptr++ != ra_tbl[ra]) {
1171                                         ra = 0;
1172                                         continue;
1173                                 }
1174                                 break;
1175
1176                          case 4:
1177                                 /*
1178                                  * skip version number
1179                                  */
1180                                 bptr++;
1181                                 break;
1182
1183                          case 5:
1184                                 /*
1185                                  * The difference between versions 1.0 and
1186                                  * 2.0 is here. For future versions of
1187                                  * the player this may need to be modified.
1188                                  */
1189                                 if (*(bptr + 1) == 0x02)
1190                                    bptr += 8;
1191                                 else
1192                                    bptr += 4;
1193                                 break;
1194
1195                          case 6:
1196                                 /* This is the field containing the port
1197                                  * number that RA-player is listening to.
1198                                  */
1199                                 lport = (((u_char*)bptr)[0] << 8)
1200                                 + ((u_char *)bptr)[1];
1201                                 if (lport < 6970)
1202                                    lport += 256;   /* don't know why */
1203                                 if (lport < 6970 || lport > 7170)
1204                                    return 1;       /* failed */
1205
1206                                 /* try to get udp port between 6970 - 7170 */
1207                                 for (p = 6970; p < 7071; p++) {
1208                                         if (udp_listen( htons(p),
1209                                                        so->so_laddr.s_addr,
1210                                                        htons(lport),
1211                                                        SS_FACCEPTONCE)) {
1212                                                 break;
1213                                         }
1214                                 }
1215                                 if (p == 7071)
1216                                    p = 0;
1217                                 *(u_char *)bptr++ = (p >> 8) & 0xff;
1218                                 *(u_char *)bptr++ = p & 0xff;
1219                                 ra = 0;
1220                                 return 1;   /* port redirected, we're done */
1221                                 break;
1222
1223                          default:
1224                                 ra = 0;
1225                         }
1226                         ra++;
1227                 }
1228                 return 1;
1229
1230          default:
1231                 /* Ooops, not emulated, won't call tcp_emu again */
1232                 so->so_emu = 0;
1233                 return 1;
1234         }
1235 }
1236
1237 /*
1238  * Do misc. config of SLiRP while its running.
1239  * Return 0 if this connections is to be closed, 1 otherwise,
1240  * return 2 if this is a command-line connection
1241  */
1242 int
1243 tcp_ctl(so)
1244         struct socket *so;
1245 {
1246         struct sbuf *sb = &so->so_snd;
1247         int command;
1248         struct ex_list *ex_ptr;
1249         int do_pty;
1250         //      struct socket *tmpso;
1251
1252         DEBUG_CALL("tcp_ctl");
1253         DEBUG_ARG("so = %lx", (long )so);
1254
1255 #if 0
1256         /*
1257          * Check if they're authorised
1258          */
1259         if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
1260                 sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
1261                 sb->sb_wptr += sb->sb_cc;
1262                 return 0;
1263         }
1264 #endif
1265         command = (ntohl(so->so_faddr.s_addr) & 0xff);
1266
1267         switch(command) {
1268         default: /* Check for exec's */
1269
1270                 /*
1271                  * Check if it's pty_exec
1272                  */
1273                 for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1274                         if (ex_ptr->ex_fport == so->so_fport &&
1275                             command == ex_ptr->ex_addr) {
1276                                 do_pty = ex_ptr->ex_pty;
1277                                 goto do_exec;
1278                         }
1279                 }
1280
1281                 /*
1282                  * Nothing bound..
1283                  */
1284                 /* tcp_fconnect(so); */
1285
1286                 /* FALLTHROUGH */
1287         case CTL_ALIAS:
1288           sb->sb_cc = sprintf(sb->sb_wptr,
1289                               "Error: No application configured.\r\n");
1290           sb->sb_wptr += sb->sb_cc;
1291           return(0);
1292
1293         do_exec:
1294                 DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
1295                 return(fork_exec(so, ex_ptr->ex_exec, do_pty));
1296
1297 #if 0
1298         case CTL_CMD:
1299            for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
1300              if (tmpso->so_emu == EMU_CTL &&
1301                  !(tmpso->so_tcpcb?
1302                    (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
1303                    :0)) {
1304                /* Ooops, control connection already active */
1305                sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
1306                sb->sb_wptr += sb->sb_cc;
1307                return 0;
1308              }
1309            }
1310            so->so_emu = EMU_CTL;
1311            ctl_password_ok = 0;
1312            sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
1313            sb->sb_wptr += sb->sb_cc;
1314            do_echo=-1;
1315            return(2);
1316 #endif
1317         }
1318 }