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 int     tcp_mssdflt = TCP_MSS;
  50 int     tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
  51 int     tcp_do_rfc1323 = 0;     /* Don't do rfc1323 performance enhancements */
  52 int     tcp_rcvspace;   /* You may want to change this */
  53 int     tcp_sndspace;   /* Keep small if you have an error prone link */
  54
  55 /*
  56  * Tcp initialization
  57  */
  58 void
  59 tcp_init()
  60 {
  61         tcp_iss = 1;            /* wrong */
  62         tcb.so_next = tcb.so_prev = &tcb;
  63
  64         /* tcp_rcvspace = our Window we advertise to the remote */
  65         tcp_rcvspace = TCP_RCVSPACE;
  66         tcp_sndspace = TCP_SNDSPACE;
  67
  68         /* Make sure tcp_sndspace is at least 2*MSS */
  69         if (tcp_sndspace < 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr)))
  70                 tcp_sndspace = 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr));
  71 }
  72
  73 /*
  74  * Create template to be used to send tcp packets on a connection.
  75  * Call after host entry created, fills
  76  * in a skeletal tcp/ip header, minimizing the amount of work
  77  * necessary when the connection is used.
  78  */
  79 /* struct tcpiphdr * */
  80 void
  81 tcp_template(tp)
  82         struct tcpcb *tp;
  83 {
  84         struct socket *so = tp->t_socket;
  85         register struct tcpiphdr *n = &tp->t_template;
  86
  87         n->ti_next = n->ti_prev = 0;
  88         n->ti_x1 = 0;
  89         n->ti_pr = IPPROTO_TCP;
  90         n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
  91         n->ti_src = so->so_faddr;
  92         n->ti_dst = so->so_laddr;
  93         n->ti_sport = so->so_fport;
  94         n->ti_dport = so->so_lport;
  95
  96         n->ti_seq = 0;
  97         n->ti_ack = 0;
  98         n->ti_x2 = 0;
  99         n->ti_off = 5;
 100         n->ti_flags = 0;
 101         n->ti_win = 0;
 102         n->ti_sum = 0;
 103         n->ti_urp = 0;
 104 }
 105
 106 /*
 107  * Send a single message to the TCP at address specified by
 108  * the given TCP/IP header.  If m == 0, then we make a copy
 109  * of the tcpiphdr at ti and send directly to the addressed host.
 110  * This is used to force keep alive messages out using the TCP
 111  * template for a connection tp->t_template.  If flags are given
 112  * then we send a message back to the TCP which originated the
 113  * segment ti, and discard the mbuf containing it and any other
 114  * attached mbufs.
 115  *
 116  * In any case the ack and sequence number of the transmitted
 117  * segment are as specified by the parameters.
 118  */
 119 void
 120 tcp_respond(tp, ti, m, ack, seq, flags)
 121         struct tcpcb *tp;
 122         register struct tcpiphdr *ti;
 123         register struct mbuf *m;
 124         tcp_seq ack, seq;
 125         int flags;
 126 {
 127         register int tlen;
 128         int win = 0;
 129
 130         DEBUG_CALL("tcp_respond");
 131         DEBUG_ARG("tp = %lx", (long)tp);
 132         DEBUG_ARG("ti = %lx", (long)ti);
 133         DEBUG_ARG("m = %lx", (long)m);
 134         DEBUG_ARG("ack = %u", ack);
 135         DEBUG_ARG("seq = %u", seq);
 136         DEBUG_ARG("flags = %x", flags);
 137
 138         if (tp)
 139                 win = sbspace(&tp->t_socket->so_rcv);
 140         if (m == 0) {
 141                 if ((m = m_get()) == NULL)
 142                         return;
 143 #ifdef TCP_COMPAT_42
 144                 tlen = 1;
 145 #else
 146                 tlen = 0;
 147 #endif
 148                 m->m_data += if_maxlinkhdr;
 149                 *mtod(m, struct tcpiphdr *) = *ti;
 150                 ti = mtod(m, struct tcpiphdr *);
 151                 flags = TH_ACK;
 152         } else {
 153                 /*
 154                  * ti points into m so the next line is just making
 155                  * the mbuf point to ti
 156                  */
 157                 m->m_data = (caddr_t)ti;
 158
 159                 m->m_len = sizeof (struct tcpiphdr);
 160                 tlen = 0;
 161 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 162                 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
 163                 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
 164 #undef xchg
 165         }
 166         ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 167         tlen += sizeof (struct tcpiphdr);
 168         m->m_len = tlen;
 169
 170         ti->ti_next = ti->ti_prev = 0;
 171         ti->ti_x1 = 0;
 172         ti->ti_seq = htonl(seq);
 173         ti->ti_ack = htonl(ack);
 174         ti->ti_x2 = 0;
 175         ti->ti_off = sizeof (struct tcphdr) >> 2;
 176         ti->ti_flags = flags;
 177         if (tp)
 178                 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
 179         else
 180                 ti->ti_win = htons((u_int16_t)win);
 181         ti->ti_urp = 0;
 182         ti->ti_sum = 0;
 183         ti->ti_sum = cksum(m, tlen);
 184         ((struct ip *)ti)->ip_len = tlen;
 185
 186         if(flags & TH_RST)
 187           ((struct ip *)ti)->ip_ttl = MAXTTL;
 188         else
 189           ((struct ip *)ti)->ip_ttl = ip_defttl;
 190
 191         (void) ip_output((struct socket *)0, m);
 192 }
 193
 194 /*
 195  * Create a new TCP control block, making an
 196  * empty reassembly queue and hooking it to the argument
 197  * protocol control block.
 198  */
 199 struct tcpcb *
 200 tcp_newtcpcb(so)
 201         struct socket *so;
 202 {
 203         register struct tcpcb *tp;
 204
 205         tp = (struct tcpcb *)malloc(sizeof(*tp));
 206         if (tp == NULL)
 207                 return ((struct tcpcb *)0);
 208
 209         memset((char *) tp, 0, sizeof(struct tcpcb));
 210         tp->seg_next = tp->seg_prev = (tcpiphdrp_32)tp;
 211         tp->t_maxseg = tcp_mssdflt;
 212
 213         tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 214         tp->t_socket = so;
 215
 216         /*
 217          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 218          * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 219          * reasonable initial retransmit time.
 220          */
 221         tp->t_srtt = TCPTV_SRTTBASE;
 222         tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2;
 223         tp->t_rttmin = TCPTV_MIN;
 224
 225         TCPT_RANGESET(tp->t_rxtcur,
 226             ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 227             TCPTV_MIN, TCPTV_REXMTMAX);
 228
 229         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 230         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 231         tp->t_state = TCPS_CLOSED;
 232
 233         so->so_tcpcb = tp;
 234
 235         return (tp);
 236 }
 237
 238 /*
 239  * Drop a TCP connection, reporting
 240  * the specified error.  If connection is synchronized,
 241  * then send a RST to peer.
 242  */
 243 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 244 {
 245 /* tcp_drop(tp, errno)
 246         register struct tcpcb *tp;
 247         int errno;
 248 {
 249 */
 250
 251         DEBUG_CALL("tcp_drop");
 252         DEBUG_ARG("tp = %lx", (long)tp);
 253         DEBUG_ARG("errno = %d", errno);
 254
 255         if (TCPS_HAVERCVDSYN(tp->t_state)) {
 256                 tp->t_state = TCPS_CLOSED;
 257                 (void) tcp_output(tp);
 258                 tcpstat.tcps_drops++;
 259         } else
 260                 tcpstat.tcps_conndrops++;
 261 /*      if (errno == ETIMEDOUT && tp->t_softerror)
 262  *              errno = tp->t_softerror;
 263  */
 264 /*      so->so_error = errno; */
 265         return (tcp_close(tp));
 266 }
 267
 268 /*
 269  * Close a TCP control block:
 270  *      discard all space held by the tcp
 271  *      discard internet protocol block
 272  *      wake up any sleepers
 273  */
 274 struct tcpcb *
 275 tcp_close(tp)
 276         register struct tcpcb *tp;
 277 {
 278         register struct tcpiphdr *t;
 279         struct socket *so = tp->t_socket;
 280         register struct mbuf *m;
 281
 282         DEBUG_CALL("tcp_close");
 283         DEBUG_ARG("tp = %lx", (long )tp);
 284
 285         /* free the reassembly queue, if any */
 286         t = (struct tcpiphdr *) tp->seg_next;
 287         while (t != (struct tcpiphdr *)tp) {
 288                 t = (struct tcpiphdr *)t->ti_next;
 289                 m = (struct mbuf *) REASS_MBUF((struct tcpiphdr *)t->ti_prev);
 290                 remque_32((struct tcpiphdr *) t->ti_prev);
 291                 m_freem(m);
 292         }
 293         /* It's static */
 294 /*      if (tp->t_template)
 295  *              (void) m_free(dtom(tp->t_template));
 296  */
 297 /*      free(tp, M_PCB);  */
 298         free(tp);
 299         so->so_tcpcb = 0;
 300         soisfdisconnected(so);
 301         /* clobber input socket cache if we're closing the cached connection */
 302         if (so == tcp_last_so)
 303                 tcp_last_so = &tcb;
 304         closesocket(so->s);
 305         sbfree(&so->so_rcv);
 306         sbfree(&so->so_snd);
 307         sofree(so);
 308         tcpstat.tcps_closed++;
 309         return ((struct tcpcb *)0);
 310 }
 311
 312 void
 313 tcp_drain()
 314 {
 315         /* XXX */
 316 }
 317
 318 /*
 319  * When a source quench is received, close congestion window
 320  * to one segment.  We will gradually open it again as we proceed.
 321  */
 322
 323 #ifdef notdef
 324
 325 void
 326 tcp_quench(i, errno)
 327
 328         int errno;
 329 {
 330         struct tcpcb *tp = intotcpcb(inp);
 331
 332         if (tp)
 333                 tp->snd_cwnd = tp->t_maxseg;
 334 }
 335
 336 #endif /* notdef */
 337
 338 /*
 339  * TCP protocol interface to socket abstraction.
 340  */
 341
 342 /*
 343  * User issued close, and wish to trail through shutdown states:
 344  * if never received SYN, just forget it.  If got a SYN from peer,
 345  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 346  * If already got a FIN from peer, then almost done; go to LAST_ACK
 347  * state.  In all other cases, have already sent FIN to peer (e.g.
 348  * after PRU_SHUTDOWN), and just have to play tedious game waiting
 349  * for peer to send FIN or not respond to keep-alives, etc.
 350  * We can let the user exit from the close as soon as the FIN is acked.
 351  */
 352 void
 353 tcp_sockclosed(tp)
 354         struct tcpcb *tp;
 355 {
 356
 357         DEBUG_CALL("tcp_sockclosed");
 358         DEBUG_ARG("tp = %lx", (long)tp);
 359
 360         switch (tp->t_state) {
 361
 362         case TCPS_CLOSED:
 363         case TCPS_LISTEN:
 364         case TCPS_SYN_SENT:
 365                 tp->t_state = TCPS_CLOSED;
 366                 tp = tcp_close(tp);
 367                 break;
 368
 369         case TCPS_SYN_RECEIVED:
 370         case TCPS_ESTABLISHED:
 371                 tp->t_state = TCPS_FIN_WAIT_1;
 372                 break;
 373
 374         case TCPS_CLOSE_WAIT:
 375                 tp->t_state = TCPS_LAST_ACK;
 376                 break;
 377         }
 378 /*      soisfdisconnecting(tp->t_socket); */
 379         if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
 380                 soisfdisconnected(tp->t_socket);
 381         if (tp)
 382                 tcp_output(tp);
 383 }
 384
 385 /*
 386  * Connect to a host on the Internet
 387  * Called by tcp_input
 388  * Only do a connect, the tcp fields will be set in tcp_input
 389  * return 0 if there's a result of the connect,
 390  * else return -1 means we're still connecting
 391  * The return value is almost always -1 since the socket is
 392  * nonblocking.  Connect returns after the SYN is sent, and does
 393  * not wait for ACK+SYN.
 394  */
 395 int tcp_fconnect(so)
 396      struct socket *so;
 397 {
 398   int ret=0;
 399
 400   DEBUG_CALL("tcp_fconnect");
 401   DEBUG_ARG("so = %lx", (long )so);
 402
 403   if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
 404     int opt, s=so->s;
 405     struct sockaddr_in addr;
 406
 407     fd_nonblock(s);
 408     opt = 1;
 409     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
 410     opt = 1;
 411     setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
 412
 413     addr.sin_family = AF_INET;
 414     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 415       /* It's an alias */
 416       switch(ntohl(so->so_faddr.s_addr) & 0xff) {
 417       case CTL_DNS:
 418         addr.sin_addr = dns_addr;
 419         break;
 420       case CTL_ALIAS:
 421       default:
 422         addr.sin_addr = loopback_addr;
 423         break;
 424       }
 425     } else
 426       addr.sin_addr = so->so_faddr;
 427     addr.sin_port = so->so_fport;
 428
 429     DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
 430                 "addr.sin_addr.s_addr=%.16s\n",
 431                 ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
 432     /* We don't care what port we get */
 433     ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
 434
 435     /*
 436      * If it's not in progress, it failed, so we just return 0,
 437      * without clearing SS_NOFDREF
 438      */
 439     soisfconnecting(so);
 440   }
 441
 442   return(ret);
 443 }
 444
 445 /*
 446  * Accept the socket and connect to the local-host
 447  *
 448  * We have a problem. The correct thing to do would be
 449  * to first connect to the local-host, and only if the
 450  * connection is accepted, then do an accept() here.
 451  * But, a) we need to know who's trying to connect
 452  * to the socket to be able to SYN the local-host, and
 453  * b) we are already connected to the foreign host by
 454  * the time it gets to accept(), so... We simply accept
 455  * here and SYN the local-host.
 456  */
 457 void
 458 tcp_connect(inso)
 459         struct socket *inso;
 460 {
 461         struct socket *so;
 462         struct sockaddr_in addr;
 463         int addrlen = sizeof(struct sockaddr_in);
 464         struct tcpcb *tp;
 465         int s, opt;
 466
 467         DEBUG_CALL("tcp_connect");
 468         DEBUG_ARG("inso = %lx", (long)inso);
 469
 470         /*
 471          * If it's an SS_ACCEPTONCE socket, no need to socreate()
 472          * another socket, just use the accept() socket.
 473          */
 474         if (inso->so_state & SS_FACCEPTONCE) {
 475                 /* FACCEPTONCE already have a tcpcb */
 476                 so = inso;
 477         } else {
 478                 if ((so = socreate()) == NULL) {
 479                         /* If it failed, get rid of the pending connection */
 480                         closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
 481                         return;
 482                 }
 483                 if (tcp_attach(so) < 0) {
 484                         free(so); /* NOT sofree */
 485                         return;
 486                 }
 487                 so->so_laddr = inso->so_laddr;
 488                 so->so_lport = inso->so_lport;
 489         }
 490
 491         (void) tcp_mss(sototcpcb(so), 0);
 492
 493         if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
 494                 tcp_close(sototcpcb(so)); /* This will sofree() as well */
 495                 return;
 496         }
 497         fd_nonblock(s);
 498         opt = 1;
 499         setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 500         opt = 1;
 501         setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
 502         opt = 1;
 503         setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));
 504
 505         so->so_fport = addr.sin_port;
 506         so->so_faddr = addr.sin_addr;
 507         /* Translate connections from localhost to the real hostname */
 508         if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
 509            so->so_faddr = alias_addr;
 510
 511         /* Close the accept() socket, set right state */
 512         if (inso->so_state & SS_FACCEPTONCE) {
 513                 closesocket(so->s); /* If we only accept once, close the accept() socket */
 514                 so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
 515                                            /* if it's not FACCEPTONCE, it's already NOFDREF */
 516         }
 517         so->s = s;
 518
 519         so->so_iptos = tcp_tos(so);
 520         tp = sototcpcb(so);
 521
 522         tcp_template(tp);
 523
 524         /* Compute window scaling to request.  */
 525 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 526  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 527  *              tp->request_r_scale++;
 528  */
 529
 530 /*      soisconnecting(so); */ /* NOFDREF used instead */
 531         tcpstat.tcps_connattempt++;
 532
 533         tp->t_state = TCPS_SYN_SENT;
 534         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 535         tp->iss = tcp_iss;
 536         tcp_iss += TCP_ISSINCR/2;
 537         tcp_sendseqinit(tp);
 538         tcp_output(tp);
 539 }
 540
 541 /*
 542  * Attach a TCPCB to a socket.
 543  */
 544 int
 545 tcp_attach(so)
 546         struct socket *so;
 547 {
 548         if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 549            return -1;
 550
 551         insque(so, &tcb);
 552
 553         return 0;
 554 }
 555
 556 /*
 557  * Set the socket's type of service field
 558  */
 559 struct tos_t tcptos[] = {
 560           {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 561           {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 562           {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 563           {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 564           {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 565           {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 566           {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 567           {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 568           {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 569           {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 570           {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 571           {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 572           {0, 0, 0, 0}
 573 };
 574
 575 struct emu_t *tcpemu = 0;
 576
 577 /*
 578  * Return TOS according to the above table
 579  */
 580 u_int8_t
 581 tcp_tos(so)
 582         struct socket *so;
 583 {
 584         int i = 0;
 585         struct emu_t *emup;
 586
 587         while(tcptos[i].tos) {
 588                 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 589                     (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 590                         so->so_emu = tcptos[i].emu;
 591                         return tcptos[i].tos;
 592                 }
 593                 i++;
 594         }
 595
 596         /* Nope, lets see if there's a user-added one */
 597         for (emup = tcpemu; emup; emup = emup->next) {
 598                 if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 599                     (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 600                         so->so_emu = emup->emu;
 601                         return emup->tos;
 602                 }
 603         }
 604
 605         return 0;
 606 }
 607
 608 int do_echo = -1;
 609
 610 /*
 611  * Emulate programs that try and connect to us
 612  * This includes ftp (the data connection is
 613  * initiated by the server) and IRC (DCC CHAT and
 614  * DCC SEND) for now
 615  *
 616  * NOTE: It's possible to crash SLiRP by sending it
 617  * unstandard strings to emulate... if this is a problem,
 618  * more checks are needed here
 619  *
 620  * XXX Assumes the whole command came in one packet
 621  *
 622  * XXX Some ftp clients will have their TOS set to
 623  * LOWDELAY and so Nagel will kick in.  Because of this,
 624  * we'll get the first letter, followed by the rest, so
 625  * we simply scan for ORT instead of PORT...
 626  * DCC doesn't have this problem because there's other stuff
 627  * in the packet before the DCC command.
 628  *
 629  * Return 1 if the mbuf m is still valid and should be
 630  * sbappend()ed
 631  *
 632  * NOTE: if you return 0 you MUST m_free() the mbuf!
 633  */
 634 int
 635 tcp_emu(so, m)
 636         struct socket *so;
 637         struct mbuf *m;
 638 {
 639         u_int n1, n2, n3, n4, n5, n6;
 640         char buff[256];
 641         u_int32_t laddr;
 642         u_int lport;
 643         char *bptr;
 644
 645         DEBUG_CALL("tcp_emu");
 646         DEBUG_ARG("so = %lx", (long)so);
 647         DEBUG_ARG("m = %lx", (long)m);
 648
 649         switch(so->so_emu) {
 650                 int x, i;
 651
 652          case EMU_IDENT:
 653                 /*
 654                  * Identification protocol as per rfc-1413
 655                  */
 656
 657                 {
 658                         struct socket *tmpso;
 659                         struct sockaddr_in addr;
 660                         int addrlen = sizeof(struct sockaddr_in);
 661                         struct sbuf *so_rcv = &so->so_rcv;
 662
 663                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 664                         so_rcv->sb_wptr += m->m_len;
 665                         so_rcv->sb_rptr += m->m_len;
 666                         m->m_data[m->m_len] = 0; /* NULL terminate */
 667                         if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 668                                 if (sscanf(so_rcv->sb_data, "%d%*[ ,]%d", &n1, &n2) == 2) {
 669                                         HTONS(n1);
 670                                         HTONS(n2);
 671                                         /* n2 is the one on our host */
 672                                         for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
 673                                                 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 674                                                     tmpso->so_lport == n2 &&
 675                                                     tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 676                                                     tmpso->so_fport == n1) {
 677                                                         if (getsockname(tmpso->s,
 678                                                                 (struct sockaddr *)&addr, &addrlen) == 0)
 679                                                            n2 = ntohs(addr.sin_port);
 680                                                         break;
 681                                                 }
 682                                         }
 683                                 }
 684                                 so_rcv->sb_cc = sprintf(so_rcv->sb_data, "%d,%d\r\n", n1, n2);
 685                                 so_rcv->sb_rptr = so_rcv->sb_data;
 686                                 so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 687                         }
 688                         m_free(m);
 689                         return 0;
 690                 }
 691
 692 #if 0
 693          case EMU_RLOGIN:
 694                 /*
 695                  * Rlogin emulation
 696                  * First we accumulate all the initial option negotiation,
 697                  * then fork_exec() rlogin according to the  options
 698                  */
 699                 {
 700                         int i, i2, n;
 701                         char *ptr;
 702                         char args[100];
 703                         char term[100];
 704                         struct sbuf *so_snd = &so->so_snd;
 705                         struct sbuf *so_rcv = &so->so_rcv;
 706
 707                         /* First check if they have a priveladged port, or too much data has arrived */
 708                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 709                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 710                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 711                                 so_snd->sb_wptr += 18;
 712                                 so_snd->sb_cc += 18;
 713                                 tcp_sockclosed(sototcpcb(so));
 714                                 m_free(m);
 715                                 return 0;
 716                         }
 717
 718                         /* Append the current data */
 719                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 720                         so_rcv->sb_wptr += m->m_len;
 721                         so_rcv->sb_rptr += m->m_len;
 722                         m_free(m);
 723
 724                         /*
 725                          * Check if we have all the initial options,
 726                          * and build argument list to rlogin while we're here
 727                          */
 728                         n = 0;
 729                         ptr = so_rcv->sb_data;
 730                         args[0] = 0;
 731                         term[0] = 0;
 732                         while (ptr < so_rcv->sb_wptr) {
 733                                 if (*ptr++ == 0) {
 734                                         n++;
 735                                         if (n == 2) {
 736                                                 sprintf(args, "rlogin -l %s %s",
 737                                                         ptr, inet_ntoa(so->so_faddr));
 738                                         } else if (n == 3) {
 739                                                 i2 = so_rcv->sb_wptr - ptr;
 740                                                 for (i = 0; i < i2; i++) {
 741                                                         if (ptr[i] == '/') {
 742                                                                 ptr[i] = 0;
 743 #ifdef HAVE_SETENV
 744                                                                 sprintf(term, "%s", ptr);
 745 #else
 746                                                                 sprintf(term, "TERM=%s", ptr);
 747 #endif
 748                                                                 ptr[i] = '/';
 749                                                                 break;
 750                                                         }
 751                                                 }
 752                                         }
 753                                 }
 754                         }
 755
 756                         if (n != 4)
 757                            return 0;
 758
 759                         /* We have it, set our term variable and fork_exec() */
 760 #ifdef HAVE_SETENV
 761                         setenv("TERM", term, 1);
 762 #else
 763                         putenv(term);
 764 #endif
 765                         fork_exec(so, args, 2);
 766                         term[0] = 0;
 767                         so->so_emu = 0;
 768
 769                         /* And finally, send the client a 0 character */
 770                         so_snd->sb_wptr[0] = 0;
 771                         so_snd->sb_wptr++;
 772                         so_snd->sb_cc++;
 773
 774                         return 0;
 775                 }
 776
 777          case EMU_RSH:
 778                 /*
 779                  * rsh emulation
 780                  * First we accumulate all the initial option negotiation,
 781                  * then rsh_exec() rsh according to the  options
 782                  */
 783                 {
 784                         int  n;
 785                         char *ptr;
 786                         char *user;
 787                         char *args;
 788                         struct sbuf *so_snd = &so->so_snd;
 789                         struct sbuf *so_rcv = &so->so_rcv;
 790
 791                         /* First check if they have a priveladged port, or too much data has arrived */
 792                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 793                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 794                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 795                                 so_snd->sb_wptr += 18;
 796                                 so_snd->sb_cc += 18;
 797                                 tcp_sockclosed(sototcpcb(so));
 798                                 m_free(m);
 799                                 return 0;
 800                         }
 801
 802                         /* Append the current data */
 803                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 804                         so_rcv->sb_wptr += m->m_len;
 805                         so_rcv->sb_rptr += m->m_len;
 806                         m_free(m);
 807
 808                         /*
 809                          * Check if we have all the initial options,
 810                          * and build argument list to rlogin while we're here
 811                          */
 812                         n = 0;
 813                         ptr = so_rcv->sb_data;
 814                         user="";
 815                         args="";
 816                         if (so->extra==NULL) {
 817                                 struct socket *ns;
 818                                 struct tcpcb* tp;
 819                                 int port=atoi(ptr);
 820                                 if (port <= 0) return 0;
 821                 if (port > 1023 || port < 512) {
 822                   memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 823                   so_snd->sb_wptr += 18;
 824                   so_snd->sb_cc += 18;
 825                   tcp_sockclosed(sototcpcb(so));
 826                   return 0;
 827                 }
 828                                 if ((ns=socreate()) == NULL)
 829                   return 0;
 830                                 if (tcp_attach(ns)<0) {
 831                   free(ns);
 832                   return 0;
 833                                 }
 834
 835                                 ns->so_laddr=so->so_laddr;
 836                                 ns->so_lport=htons(port);
 837
 838                                 (void) tcp_mss(sototcpcb(ns), 0);
 839
 840                                 ns->so_faddr=so->so_faddr;
 841                                 ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */
 842
 843                                 if (ns->so_faddr.s_addr == 0 ||
 844                                         ns->so_faddr.s_addr == loopback_addr.s_addr)
 845                   ns->so_faddr = alias_addr;
 846
 847                                 ns->so_iptos = tcp_tos(ns);
 848                                 tp = sototcpcb(ns);
 849
 850                                 tcp_template(tp);
 851
 852                                 /* Compute window scaling to request.  */
 853                                 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 854                                  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 855                                  *              tp->request_r_scale++;
 856                                  */
 857
 858                 /*soisfconnecting(ns);*/
 859
 860                                 tcpstat.tcps_connattempt++;
 861
 862                                 tp->t_state = TCPS_SYN_SENT;
 863                                 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 864                                 tp->iss = tcp_iss;
 865                                 tcp_iss += TCP_ISSINCR/2;
 866                                 tcp_sendseqinit(tp);
 867                                 tcp_output(tp);
 868                                 so->extra=ns;
 869                         }
 870                         while (ptr < so_rcv->sb_wptr) {
 871               if (*ptr++ == 0) {
 872                 n++;
 873                 if (n == 2) {
 874                   user=ptr;
 875                 } else if (n == 3) {
 876                   args=ptr;
 877                 }
 878               }
 879                         }
 880
 881                         if (n != 4)
 882               return 0;
 883
 884                         rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
 885                         so->so_emu = 0;
 886                         so->extra=NULL;
 887
 888                         /* And finally, send the client a 0 character */
 889                         so_snd->sb_wptr[0] = 0;
 890                         so_snd->sb_wptr++;
 891                         so_snd->sb_cc++;
 892
 893                         return 0;
 894                 }
 895
 896          case EMU_CTL:
 897                 {
 898                         int num;
 899                         struct sbuf *so_snd = &so->so_snd;
 900                         struct sbuf *so_rcv = &so->so_rcv;
 901
 902                         /*
 903                          * If there is binary data here, we save it in so->so_m
 904                          */
 905                         if (!so->so_m) {
 906                           int rxlen;
 907                           char *rxdata;
 908                           rxdata=mtod(m, char *);
 909                           for (rxlen=m->m_len; rxlen; rxlen--) {
 910                             if (*rxdata++ & 0x80) {
 911                               so->so_m = m;
 912                               return 0;
 913                             }
 914                           }
 915                         } /* if(so->so_m==NULL) */
 916
 917                         /*
 918                          * Append the line
 919                          */
 920                         sbappendsb(so_rcv, m);
 921
 922                         /* To avoid going over the edge of the buffer, we reset it */
 923                         if (so_snd->sb_cc == 0)
 924                            so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;
 925
 926                         /*
 927                          * A bit of a hack:
 928                          * If the first packet we get here is 1 byte long, then it
 929                          * was done in telnet character mode, therefore we must echo
 930                          * the characters as they come.  Otherwise, we echo nothing,
 931                          * because in linemode, the line is already echoed
 932                          * XXX two or more control connections won't work
 933                          */
 934                         if (do_echo == -1) {
 935                                 if (m->m_len == 1) do_echo = 1;
 936                                 else do_echo = 0;
 937                         }
 938                         if (do_echo) {
 939                           sbappendsb(so_snd, m);
 940                           m_free(m);
 941                           tcp_output(sototcpcb(so)); /* XXX */
 942                         } else
 943                           m_free(m);
 944
 945                         num = 0;
 946                         while (num < so->so_rcv.sb_cc) {
 947                                 if (*(so->so_rcv.sb_rptr + num) == '\n' ||
 948                                     *(so->so_rcv.sb_rptr + num) == '\r') {
 949                                         int n;
 950
 951                                         *(so_rcv->sb_rptr + num) = 0;
 952                                         if (ctl_password && !ctl_password_ok) {
 953                                                 /* Need a password */
 954                                                 if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
 955                                                         if (strcmp(buff, ctl_password) == 0) {
 956                                                                 ctl_password_ok = 1;
 957                                                                 n = sprintf(so_snd->sb_wptr,
 958                                                                             "Password OK.\r\n");
 959                                                                 goto do_prompt;
 960                                                         }
 961                                                 }
 962                                                 n = sprintf(so_snd->sb_wptr,
 963                                          "Error: Password required, log on with \"pass PASSWORD\"\r\n");
 964                                                 goto do_prompt;
 965                                         }
 966                                         cfg_quitting = 0;
 967                                         n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
 968                                         if (!cfg_quitting) {
 969                                                 /* Register the printed data */
 970 do_prompt:
 971                                                 so_snd->sb_cc += n;
 972                                                 so_snd->sb_wptr += n;
 973                                                 /* Add prompt */
 974                                                 n = sprintf(so_snd->sb_wptr, "Slirp> ");
 975                                                 so_snd->sb_cc += n;
 976                                                 so_snd->sb_wptr += n;
 977                                         }
 978                                         /* Drop so_rcv data */
 979                                         so_rcv->sb_cc = 0;
 980                                         so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
 981                                         tcp_output(sototcpcb(so)); /* Send the reply */
 982                                 }
 983                                 num++;
 984                         }
 985                         return 0;
 986                 }
 987 #endif
 988         case EMU_FTP: /* ftp */
 989                 *(m->m_data+m->m_len) = 0; /* NULL terminate for strstr */
 990                 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 991                         /*
 992                          * Need to emulate the PORT command
 993                          */
 994                         x = sscanf(bptr, "ORT %d,%d,%d,%d,%d,%d\r\n%256[^\177]",
 995                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 996                         if (x < 6)
 997                            return 1;
 998
 999                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
1000                         lport = htons((n5 << 8) | (n6));
1001
1002                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
1003                            return 1;
1004
1005                         n6 = ntohs(so->so_fport);
1006
1007                         n5 = (n6 >> 8) & 0xff;
1008                         n6 &= 0xff;
1009
1010                         laddr = ntohl(so->so_faddr.s_addr);
1011
1012                         n1 = ((laddr >> 24) & 0xff);
1013                         n2 = ((laddr >> 16) & 0xff);
1014                         n3 = ((laddr >> 8)  & 0xff);
1015                         n4 =  (laddr & 0xff);
1016
1017                         m->m_len = bptr - m->m_data; /* Adjust length */
1018                         m->m_len += sprintf(bptr,"ORT %d,%d,%d,%d,%d,%d\r\n%s",
1019                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
1020                         return 1;
1021                 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
1022                         /*
1023                          * Need to emulate the PASV response
1024                          */
1025                         x = sscanf(bptr, "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%256[^\177]",
1026                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
1027                         if (x < 6)
1028                            return 1;
1029
1030                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
1031                         lport = htons((n5 << 8) | (n6));
1032
1033                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
1034                            return 1;
1035
1036                         n6 = ntohs(so->so_fport);
1037
1038                         n5 = (n6 >> 8) & 0xff;
1039                         n6 &= 0xff;
1040
1041                         laddr = ntohl(so->so_faddr.s_addr);
1042
1043                         n1 = ((laddr >> 24) & 0xff);
1044                         n2 = ((laddr >> 16) & 0xff);
1045                         n3 = ((laddr >> 8)  & 0xff);
1046                         n4 =  (laddr & 0xff);
1047
1048                         m->m_len = bptr - m->m_data; /* Adjust length */
1049                         m->m_len += sprintf(bptr,"27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
1050                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
1051
1052                         return 1;
1053                 }
1054
1055                 return 1;
1056
1057          case EMU_KSH:
1058                 /*
1059                  * The kshell (Kerberos rsh) and shell services both pass
1060                  * a local port port number to carry signals to the server
1061                  * and stderr to the client.  It is passed at the beginning
1062                  * of the connection as a NUL-terminated decimal ASCII string.
1063                  */
1064                 so->so_emu = 0;
1065                 for (lport = 0, i = 0; i < m->m_len-1; ++i) {
1066                         if (m->m_data[i] < '0' || m->m_data[i] > '9')
1067                                 return 1;       /* invalid number */
1068                         lport *= 10;
1069                         lport += m->m_data[i] - '0';
1070                 }
1071                 if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
1072                     (so = solisten(0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
1073                         m->m_len = sprintf(m->m_data, "%d", ntohs(so->so_fport))+1;
1074                 return 1;
1075
1076          case EMU_IRC:
1077                 /*
1078                  * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
1079                  */
1080                 *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
1081                 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
1082                          return 1;
1083
1084                 /* The %256s is for the broken mIRC */
1085                 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
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 CHAT chat %lu %u%c\n",
1091                              (unsigned long)ntohl(so->so_faddr.s_addr),
1092                              ntohs(so->so_fport), 1);
1093                 } else if (sscanf(bptr, "DCC SEND %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 SEND %s %lu %u %u%c\n",
1099                               buff, (unsigned long)ntohl(so->so_faddr.s_addr),
1100                               ntohs(so->so_fport), n1, 1);
1101                 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1102                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1103                                 return 1;
1104
1105                         m->m_len = bptr - m->m_data; /* Adjust length */
1106                         m->m_len += sprintf(bptr, "DCC MOVE %s %lu %u %u%c\n",
1107                               buff, (unsigned long)ntohl(so->so_faddr.s_addr),
1108                               ntohs(so->so_fport), n1, 1);
1109                 }
1110                 return 1;
1111
1112          case EMU_REALAUDIO:
1113                 /*
1114                  * RealAudio emulation - JP. We must try to parse the incoming
1115                  * data and try to find the two characters that contain the
1116                  * port number. Then we redirect an udp port and replace the
1117                  * number with the real port we got.
1118                  *
1119                  * The 1.0 beta versions of the player are not supported
1120                  * any more.
1121                  *
1122                  * A typical packet for player version 1.0 (release version):
1123                  *
1124                  * 0000:50 4E 41 00 05
1125                  * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
1126                  * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
1127                  * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
1128                  * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
1129                  *
1130                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1131                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1132                  * second packet. This time we received five bytes first and
1133                  * then the rest. You never know how many bytes you get.
1134                  *
1135                  * A typical packet for player version 2.0 (beta):
1136                  *
1137                  * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
1138                  * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
1139                  * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
1140                  * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
1141                  * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
1142                  *
1143                  * Port number 0x1BC1 is found at offset 0x0d.
1144                  *
1145                  * This is just a horrible switch statement. Variable ra tells
1146                  * us where we're going.
1147                  */
1148
1149                 bptr = m->m_data;
1150                 while (bptr < m->m_data + m->m_len) {
1151                         u_short p;
1152                         static int ra = 0;
1153                         char ra_tbl[4];
1154
1155                         ra_tbl[0] = 0x50;
1156                         ra_tbl[1] = 0x4e;
1157                         ra_tbl[2] = 0x41;
1158                         ra_tbl[3] = 0;
1159
1160                         switch (ra) {
1161                          case 0:
1162                          case 2:
1163                          case 3:
1164                                 if (*bptr++ != ra_tbl[ra]) {
1165                                         ra = 0;
1166                                         continue;
1167                                 }
1168                                 break;
1169
1170                          case 1:
1171                                 /*
1172                                  * We may get 0x50 several times, ignore them
1173                                  */
1174                                 if (*bptr == 0x50) {
1175                                         ra = 1;
1176                                         bptr++;
1177                                         continue;
1178                                 } else if (*bptr++ != ra_tbl[ra]) {
1179                                         ra = 0;
1180                                         continue;
1181                                 }
1182                                 break;
1183
1184                          case 4:
1185                                 /*
1186                                  * skip version number
1187                                  */
1188                                 bptr++;
1189                                 break;
1190
1191                          case 5:
1192                                 /*
1193                                  * The difference between versions 1.0 and
1194                                  * 2.0 is here. For future versions of
1195                                  * the player this may need to be modified.
1196                                  */
1197                                 if (*(bptr + 1) == 0x02)
1198                                    bptr += 8;
1199                                 else
1200                                    bptr += 4;
1201                                 break;
1202
1203                          case 6:
1204                                 /* This is the field containing the port
1205                                  * number that RA-player is listening to.
1206                                  */
1207                                 lport = (((u_char*)bptr)[0] << 8)
1208                                 + ((u_char *)bptr)[1];
1209                                 if (lport < 6970)
1210                                    lport += 256;   /* don't know why */
1211                                 if (lport < 6970 || lport > 7170)
1212                                    return 1;       /* failed */
1213
1214                                 /* try to get udp port between 6970 - 7170 */
1215                                 for (p = 6970; p < 7071; p++) {
1216                                         if (udp_listen( htons(p),
1217                                                        so->so_laddr.s_addr,
1218                                                        htons(lport),
1219                                                        SS_FACCEPTONCE)) {
1220                                                 break;
1221                                         }
1222                                 }
1223                                 if (p == 7071)
1224                                    p = 0;
1225                                 *(u_char *)bptr++ = (p >> 8) & 0xff;
1226                                 *(u_char *)bptr++ = p & 0xff;
1227                                 ra = 0;
1228                                 return 1;   /* port redirected, we're done */
1229                                 break;
1230
1231                          default:
1232                                 ra = 0;
1233                         }
1234                         ra++;
1235                 }
1236                 return 1;
1237
1238          default:
1239                 /* Ooops, not emulated, won't call tcp_emu again */
1240                 so->so_emu = 0;
1241                 return 1;
1242         }
1243 }
1244
1245 /*
1246  * Do misc. config of SLiRP while its running.
1247  * Return 0 if this connections is to be closed, 1 otherwise,
1248  * return 2 if this is a command-line connection
1249  */
1250 int
1251 tcp_ctl(so)
1252         struct socket *so;
1253 {
1254         struct sbuf *sb = &so->so_snd;
1255         int command;
1256         struct ex_list *ex_ptr;
1257         int do_pty;
1258         //      struct socket *tmpso;
1259
1260         DEBUG_CALL("tcp_ctl");
1261         DEBUG_ARG("so = %lx", (long )so);
1262
1263 #if 0
1264         /*
1265          * Check if they're authorised
1266          */
1267         if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
1268                 sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
1269                 sb->sb_wptr += sb->sb_cc;
1270                 return 0;
1271         }
1272 #endif
1273         command = (ntohl(so->so_faddr.s_addr) & 0xff);
1274
1275         switch(command) {
1276         default: /* Check for exec's */
1277
1278                 /*
1279                  * Check if it's pty_exec
1280                  */
1281                 for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1282                         if (ex_ptr->ex_fport == so->so_fport &&
1283                             command == ex_ptr->ex_addr) {
1284                                 do_pty = ex_ptr->ex_pty;
1285                                 goto do_exec;
1286                         }
1287                 }
1288
1289                 /*
1290                  * Nothing bound..
1291                  */
1292                 /* tcp_fconnect(so); */
1293
1294                 /* FALLTHROUGH */
1295         case CTL_ALIAS:
1296           sb->sb_cc = sprintf(sb->sb_wptr,
1297                               "Error: No application configured.\r\n");
1298           sb->sb_wptr += sb->sb_cc;
1299           return(0);
1300
1301         do_exec:
1302                 DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
1303                 return(fork_exec(so, ex_ptr->ex_exec, do_pty));
1304
1305 #if 0
1306         case CTL_CMD:
1307            for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
1308              if (tmpso->so_emu == EMU_CTL &&
1309                  !(tmpso->so_tcpcb?
1310                    (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
1311                    :0)) {
1312                /* Ooops, control connection already active */
1313                sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
1314                sb->sb_wptr += sb->sb_cc;
1315                return 0;
1316              }
1317            }
1318            so->so_emu = EMU_CTL;
1319            ctl_password_ok = 0;
1320            sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
1321            sb->sb_wptr += sb->sb_cc;
1322            do_echo=-1;
1323            return(2);
1324 #endif
1325         }
1326 }