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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)tcp_subr.c  8.1 (Berkeley) 6/10/93
  30  * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
  31  */
  32
  33 /*
  34  * Changes and additions relating to SLiRP
  35  * Copyright (c) 1995 Danny Gasparovski.
  36  *
  37  * Please read the file COPYRIGHT for the
  38  * terms and conditions of the copyright.
  39  */
  40
  41 #define WANT_SYS_IOCTL_H
  42 #include <slirp.h>
  43
  44 /* patchable/settable parameters for tcp */
  45 /* Don't do rfc1323 performance enhancements */
  46 #define TCP_DO_RFC1323 0
  47
  48 /*
  49  * Tcp initialization
  50  */
  51 void
  52 tcp_init()
  53 {
  54         tcp_iss = 1;            /* wrong */
  55         tcb.so_next = tcb.so_prev = &tcb;
  56 }
  57
  58 /*
  59  * Create template to be used to send tcp packets on a connection.
  60  * Call after host entry created, fills
  61  * in a skeletal tcp/ip header, minimizing the amount of work
  62  * necessary when the connection is used.
  63  */
  64 /* struct tcpiphdr * */
  65 void
  66 tcp_template(tp)
  67         struct tcpcb *tp;
  68 {
  69         struct socket *so = tp->t_socket;
  70         register struct tcpiphdr *n = &tp->t_template;
  71
  72         n->ti_mbuf = NULL;
  73         n->ti_x1 = 0;
  74         n->ti_pr = IPPROTO_TCP;
  75         n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
  76         n->ti_src = so->so_faddr;
  77         n->ti_dst = so->so_laddr;
  78         n->ti_sport = so->so_fport;
  79         n->ti_dport = so->so_lport;
  80
  81         n->ti_seq = 0;
  82         n->ti_ack = 0;
  83         n->ti_x2 = 0;
  84         n->ti_off = 5;
  85         n->ti_flags = 0;
  86         n->ti_win = 0;
  87         n->ti_sum = 0;
  88         n->ti_urp = 0;
  89 }
  90
  91 /*
  92  * Send a single message to the TCP at address specified by
  93  * the given TCP/IP header.  If m == 0, then we make a copy
  94  * of the tcpiphdr at ti and send directly to the addressed host.
  95  * This is used to force keep alive messages out using the TCP
  96  * template for a connection tp->t_template.  If flags are given
  97  * then we send a message back to the TCP which originated the
  98  * segment ti, and discard the mbuf containing it and any other
  99  * attached mbufs.
 100  *
 101  * In any case the ack and sequence number of the transmitted
 102  * segment are as specified by the parameters.
 103  */
 104 void
 105 tcp_respond(tp, ti, m, ack, seq, flags)
 106         struct tcpcb *tp;
 107         register struct tcpiphdr *ti;
 108         register struct mbuf *m;
 109         tcp_seq ack, seq;
 110         int flags;
 111 {
 112         register int tlen;
 113         int win = 0;
 114
 115         DEBUG_CALL("tcp_respond");
 116         DEBUG_ARG("tp = %lx", (long)tp);
 117         DEBUG_ARG("ti = %lx", (long)ti);
 118         DEBUG_ARG("m = %lx", (long)m);
 119         DEBUG_ARG("ack = %u", ack);
 120         DEBUG_ARG("seq = %u", seq);
 121         DEBUG_ARG("flags = %x", flags);
 122
 123         if (tp)
 124                 win = sbspace(&tp->t_socket->so_rcv);
 125         if (m == 0) {
 126                 if ((m = m_get()) == NULL)
 127                         return;
 128 #ifdef TCP_COMPAT_42
 129                 tlen = 1;
 130 #else
 131                 tlen = 0;
 132 #endif
 133                 m->m_data += IF_MAXLINKHDR;
 134                 *mtod(m, struct tcpiphdr *) = *ti;
 135                 ti = mtod(m, struct tcpiphdr *);
 136                 flags = TH_ACK;
 137         } else {
 138                 /*
 139                  * ti points into m so the next line is just making
 140                  * the mbuf point to ti
 141                  */
 142                 m->m_data = (caddr_t)ti;
 143
 144                 m->m_len = sizeof (struct tcpiphdr);
 145                 tlen = 0;
 146 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 147                 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
 148                 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
 149 #undef xchg
 150         }
 151         ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 152         tlen += sizeof (struct tcpiphdr);
 153         m->m_len = tlen;
 154
 155         ti->ti_mbuf = 0;
 156         ti->ti_x1 = 0;
 157         ti->ti_seq = htonl(seq);
 158         ti->ti_ack = htonl(ack);
 159         ti->ti_x2 = 0;
 160         ti->ti_off = sizeof (struct tcphdr) >> 2;
 161         ti->ti_flags = flags;
 162         if (tp)
 163                 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
 164         else
 165                 ti->ti_win = htons((u_int16_t)win);
 166         ti->ti_urp = 0;
 167         ti->ti_sum = 0;
 168         ti->ti_sum = cksum(m, tlen);
 169         ((struct ip *)ti)->ip_len = tlen;
 170
 171         if(flags & TH_RST)
 172           ((struct ip *)ti)->ip_ttl = MAXTTL;
 173         else
 174           ((struct ip *)ti)->ip_ttl = IPDEFTTL;
 175
 176         (void) ip_output((struct socket *)0, m);
 177 }
 178
 179 /*
 180  * Create a new TCP control block, making an
 181  * empty reassembly queue and hooking it to the argument
 182  * protocol control block.
 183  */
 184 struct tcpcb *
 185 tcp_newtcpcb(so)
 186         struct socket *so;
 187 {
 188         register struct tcpcb *tp;
 189
 190         tp = (struct tcpcb *)malloc(sizeof(*tp));
 191         if (tp == NULL)
 192                 return ((struct tcpcb *)0);
 193
 194         memset((char *) tp, 0, sizeof(struct tcpcb));
 195         tp->seg_next = tp->seg_prev = (struct tcpiphdr*)tp;
 196         tp->t_maxseg = TCP_MSS;
 197
 198         tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 199         tp->t_socket = so;
 200
 201         /*
 202          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 203          * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 204          * reasonable initial retransmit time.
 205          */
 206         tp->t_srtt = TCPTV_SRTTBASE;
 207         tp->t_rttvar = TCPTV_SRTTDFLT << 2;
 208         tp->t_rttmin = TCPTV_MIN;
 209
 210         TCPT_RANGESET(tp->t_rxtcur,
 211             ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 212             TCPTV_MIN, TCPTV_REXMTMAX);
 213
 214         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 215         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 216         tp->t_state = TCPS_CLOSED;
 217
 218         so->so_tcpcb = tp;
 219
 220         return (tp);
 221 }
 222
 223 /*
 224  * Drop a TCP connection, reporting
 225  * the specified error.  If connection is synchronized,
 226  * then send a RST to peer.
 227  */
 228 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 229 {
 230 /* tcp_drop(tp, errno)
 231         register struct tcpcb *tp;
 232         int errno;
 233 {
 234 */
 235
 236         DEBUG_CALL("tcp_drop");
 237         DEBUG_ARG("tp = %lx", (long)tp);
 238         DEBUG_ARG("errno = %d", errno);
 239
 240         if (TCPS_HAVERCVDSYN(tp->t_state)) {
 241                 tp->t_state = TCPS_CLOSED;
 242                 (void) tcp_output(tp);
 243                 STAT(tcpstat.tcps_drops++);
 244         } else
 245                 STAT(tcpstat.tcps_conndrops++);
 246 /*      if (errno == ETIMEDOUT && tp->t_softerror)
 247  *              errno = tp->t_softerror;
 248  */
 249 /*      so->so_error = errno; */
 250         return (tcp_close(tp));
 251 }
 252
 253 /*
 254  * Close a TCP control block:
 255  *      discard all space held by the tcp
 256  *      discard internet protocol block
 257  *      wake up any sleepers
 258  */
 259 struct tcpcb *
 260 tcp_close(tp)
 261         register struct tcpcb *tp;
 262 {
 263         register struct tcpiphdr *t;
 264         struct socket *so = tp->t_socket;
 265         register struct mbuf *m;
 266
 267         DEBUG_CALL("tcp_close");
 268         DEBUG_ARG("tp = %lx", (long )tp);
 269
 270         /* free the reassembly queue, if any */
 271         t = tcpfrag_list_first(tp);
 272         while (!tcpfrag_list_end(t, tp)) {
 273                 t = tcpiphdr_next(t);
 274                 m = tcpiphdr_prev(t)->ti_mbuf;
 275                 remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
 276                 m_freem(m);
 277         }
 278         /* It's static */
 279 /*      if (tp->t_template)
 280  *              (void) m_free(dtom(tp->t_template));
 281  */
 282 /*      free(tp, M_PCB);  */
 283         free(tp);
 284         so->so_tcpcb = 0;
 285         soisfdisconnected(so);
 286         /* clobber input socket cache if we're closing the cached connection */
 287         if (so == tcp_last_so)
 288                 tcp_last_so = &tcb;
 289         closesocket(so->s);
 290         sbfree(&so->so_rcv);
 291         sbfree(&so->so_snd);
 292         sofree(so);
 293         STAT(tcpstat.tcps_closed++);
 294         return ((struct tcpcb *)0);
 295 }
 296
 297 #ifdef notdef
 298 void
 299 tcp_drain()
 300 {
 301         /* XXX */
 302 }
 303
 304 /*
 305  * When a source quench is received, close congestion window
 306  * to one segment.  We will gradually open it again as we proceed.
 307  */
 308 void
 309 tcp_quench(i, errno)
 310
 311         int errno;
 312 {
 313         struct tcpcb *tp = intotcpcb(inp);
 314
 315         if (tp)
 316                 tp->snd_cwnd = tp->t_maxseg;
 317 }
 318
 319 #endif /* notdef */
 320
 321 /*
 322  * TCP protocol interface to socket abstraction.
 323  */
 324
 325 /*
 326  * User issued close, and wish to trail through shutdown states:
 327  * if never received SYN, just forget it.  If got a SYN from peer,
 328  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 329  * If already got a FIN from peer, then almost done; go to LAST_ACK
 330  * state.  In all other cases, have already sent FIN to peer (e.g.
 331  * after PRU_SHUTDOWN), and just have to play tedious game waiting
 332  * for peer to send FIN or not respond to keep-alives, etc.
 333  * We can let the user exit from the close as soon as the FIN is acked.
 334  */
 335 void
 336 tcp_sockclosed(tp)
 337         struct tcpcb *tp;
 338 {
 339
 340         DEBUG_CALL("tcp_sockclosed");
 341         DEBUG_ARG("tp = %lx", (long)tp);
 342
 343         switch (tp->t_state) {
 344
 345         case TCPS_CLOSED:
 346         case TCPS_LISTEN:
 347         case TCPS_SYN_SENT:
 348                 tp->t_state = TCPS_CLOSED;
 349                 tp = tcp_close(tp);
 350                 break;
 351
 352         case TCPS_SYN_RECEIVED:
 353         case TCPS_ESTABLISHED:
 354                 tp->t_state = TCPS_FIN_WAIT_1;
 355                 break;
 356
 357         case TCPS_CLOSE_WAIT:
 358                 tp->t_state = TCPS_LAST_ACK;
 359                 break;
 360         }
 361 /*      soisfdisconnecting(tp->t_socket); */
 362         if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
 363                 soisfdisconnected(tp->t_socket);
 364         if (tp)
 365                 tcp_output(tp);
 366 }
 367
 368 /*
 369  * Connect to a host on the Internet
 370  * Called by tcp_input
 371  * Only do a connect, the tcp fields will be set in tcp_input
 372  * return 0 if there's a result of the connect,
 373  * else return -1 means we're still connecting
 374  * The return value is almost always -1 since the socket is
 375  * nonblocking.  Connect returns after the SYN is sent, and does
 376  * not wait for ACK+SYN.
 377  */
 378 int tcp_fconnect(so)
 379      struct socket *so;
 380 {
 381   int ret=0;
 382
 383   DEBUG_CALL("tcp_fconnect");
 384   DEBUG_ARG("so = %lx", (long )so);
 385
 386   if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
 387     int opt, s=so->s;
 388     struct sockaddr_in addr;
 389
 390     fd_nonblock(s);
 391     opt = 1;
 392     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
 393     opt = 1;
 394     setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
 395
 396     addr.sin_family = AF_INET;
 397     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 398       /* It's an alias */
 399       switch(ntohl(so->so_faddr.s_addr) & 0xff) {
 400       case CTL_DNS:
 401         addr.sin_addr = dns_addr;
 402         break;
 403       case CTL_ALIAS:
 404       default:
 405         addr.sin_addr = loopback_addr;
 406         break;
 407       }
 408     } else
 409       addr.sin_addr = so->so_faddr;
 410     addr.sin_port = so->so_fport;
 411
 412     DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
 413                 "addr.sin_addr.s_addr=%.16s\n",
 414                 ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
 415     /* We don't care what port we get */
 416     ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
 417
 418     /*
 419      * If it's not in progress, it failed, so we just return 0,
 420      * without clearing SS_NOFDREF
 421      */
 422     soisfconnecting(so);
 423   }
 424
 425   return(ret);
 426 }
 427
 428 /*
 429  * Accept the socket and connect to the local-host
 430  *
 431  * We have a problem. The correct thing to do would be
 432  * to first connect to the local-host, and only if the
 433  * connection is accepted, then do an accept() here.
 434  * But, a) we need to know who's trying to connect
 435  * to the socket to be able to SYN the local-host, and
 436  * b) we are already connected to the foreign host by
 437  * the time it gets to accept(), so... We simply accept
 438  * here and SYN the local-host.
 439  */
 440 void
 441 tcp_connect(inso)
 442         struct socket *inso;
 443 {
 444         struct socket *so;
 445         struct sockaddr_in addr;
 446         socklen_t addrlen = sizeof(struct sockaddr_in);
 447         struct tcpcb *tp;
 448         int s, opt;
 449
 450         DEBUG_CALL("tcp_connect");
 451         DEBUG_ARG("inso = %lx", (long)inso);
 452
 453         /*
 454          * If it's an SS_ACCEPTONCE socket, no need to socreate()
 455          * another socket, just use the accept() socket.
 456          */
 457         if (inso->so_state & SS_FACCEPTONCE) {
 458                 /* FACCEPTONCE already have a tcpcb */
 459                 so = inso;
 460         } else {
 461                 if ((so = socreate()) == NULL) {
 462                         /* If it failed, get rid of the pending connection */
 463                         closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
 464                         return;
 465                 }
 466                 if (tcp_attach(so) < 0) {
 467                         free(so); /* NOT sofree */
 468                         return;
 469                 }
 470                 so->so_laddr = inso->so_laddr;
 471                 so->so_lport = inso->so_lport;
 472         }
 473
 474         (void) tcp_mss(sototcpcb(so), 0);
 475
 476         if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
 477                 tcp_close(sototcpcb(so)); /* This will sofree() as well */
 478                 return;
 479         }
 480         fd_nonblock(s);
 481         opt = 1;
 482         setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 483         opt = 1;
 484         setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
 485         opt = 1;
 486         setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));
 487
 488         so->so_fport = addr.sin_port;
 489         so->so_faddr = addr.sin_addr;
 490         /* Translate connections from localhost to the real hostname */
 491         if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
 492            so->so_faddr = alias_addr;
 493
 494         /* Close the accept() socket, set right state */
 495         if (inso->so_state & SS_FACCEPTONCE) {
 496                 closesocket(so->s); /* If we only accept once, close the accept() socket */
 497                 so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
 498                                            /* if it's not FACCEPTONCE, it's already NOFDREF */
 499         }
 500         so->s = s;
 501
 502         so->so_iptos = tcp_tos(so);
 503         tp = sototcpcb(so);
 504
 505         tcp_template(tp);
 506
 507         /* Compute window scaling to request.  */
 508 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 509  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 510  *              tp->request_r_scale++;
 511  */
 512
 513 /*      soisconnecting(so); */ /* NOFDREF used instead */
 514         STAT(tcpstat.tcps_connattempt++);
 515
 516         tp->t_state = TCPS_SYN_SENT;
 517         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 518         tp->iss = tcp_iss;
 519         tcp_iss += TCP_ISSINCR/2;
 520         tcp_sendseqinit(tp);
 521         tcp_output(tp);
 522 }
 523
 524 /*
 525  * Attach a TCPCB to a socket.
 526  */
 527 int
 528 tcp_attach(so)
 529         struct socket *so;
 530 {
 531         if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 532            return -1;
 533
 534         insque(so, &tcb);
 535
 536         return 0;
 537 }
 538
 539 /*
 540  * Set the socket's type of service field
 541  */
 542 static const struct tos_t tcptos[] = {
 543           {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 544           {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 545           {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 546           {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 547           {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 548           {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 549           {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 550           {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 551           {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 552           {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 553           {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 554           {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 555           {0, 0, 0, 0}
 556 };
 557
 558 #ifdef CONFIG_QEMU
 559 static
 560 #endif
 561 struct emu_t *tcpemu = 0;
 562
 563 /*
 564  * Return TOS according to the above table
 565  */
 566 u_int8_t
 567 tcp_tos(so)
 568         struct socket *so;
 569 {
 570         int i = 0;
 571         struct emu_t *emup;
 572
 573         while(tcptos[i].tos) {
 574                 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 575                     (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 576                         so->so_emu = tcptos[i].emu;
 577                         return tcptos[i].tos;
 578                 }
 579                 i++;
 580         }
 581
 582         /* Nope, lets see if there's a user-added one */
 583         for (emup = tcpemu; emup; emup = emup->next) {
 584                 if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 585                     (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 586                         so->so_emu = emup->emu;
 587                         return emup->tos;
 588                 }
 589         }
 590
 591         return 0;
 592 }
 593
 594 #if 0
 595 int do_echo = -1;
 596 #endif
 597
 598 /*
 599  * Emulate programs that try and connect to us
 600  * This includes ftp (the data connection is
 601  * initiated by the server) and IRC (DCC CHAT and
 602  * DCC SEND) for now
 603  *
 604  * NOTE: It's possible to crash SLiRP by sending it
 605  * unstandard strings to emulate... if this is a problem,
 606  * more checks are needed here
 607  *
 608  * XXX Assumes the whole command came in one packet
 609  *
 610  * XXX Some ftp clients will have their TOS set to
 611  * LOWDELAY and so Nagel will kick in.  Because of this,
 612  * we'll get the first letter, followed by the rest, so
 613  * we simply scan for ORT instead of PORT...
 614  * DCC doesn't have this problem because there's other stuff
 615  * in the packet before the DCC command.
 616  *
 617  * Return 1 if the mbuf m is still valid and should be
 618  * sbappend()ed
 619  *
 620  * NOTE: if you return 0 you MUST m_free() the mbuf!
 621  */
 622 int
 623 tcp_emu(so, m)
 624         struct socket *so;
 625         struct mbuf *m;
 626 {
 627         u_int n1, n2, n3, n4, n5, n6;
 628         char buff[257];
 629         u_int32_t laddr;
 630         u_int lport;
 631         char *bptr;
 632
 633         DEBUG_CALL("tcp_emu");
 634         DEBUG_ARG("so = %lx", (long)so);
 635         DEBUG_ARG("m = %lx", (long)m);
 636
 637         switch(so->so_emu) {
 638                 int x, i;
 639
 640          case EMU_IDENT:
 641                 /*
 642                  * Identification protocol as per rfc-1413
 643                  */
 644
 645                 {
 646                         struct socket *tmpso;
 647                         struct sockaddr_in addr;
 648                         socklen_t addrlen = sizeof(struct sockaddr_in);
 649                         struct sbuf *so_rcv = &so->so_rcv;
 650
 651                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 652                         so_rcv->sb_wptr += m->m_len;
 653                         so_rcv->sb_rptr += m->m_len;
 654                         m->m_data[m->m_len] = 0; /* NULL terminate */
 655                         if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 656                                 if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
 657                                         HTONS(n1);
 658                                         HTONS(n2);
 659                                         /* n2 is the one on our host */
 660                                         for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
 661                                                 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 662                                                     tmpso->so_lport == n2 &&
 663                                                     tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 664                                                     tmpso->so_fport == n1) {
 665                                                         if (getsockname(tmpso->s,
 666                                                                 (struct sockaddr *)&addr, &addrlen) == 0)
 667                                                            n2 = ntohs(addr.sin_port);
 668                                                         break;
 669                                                 }
 670                                         }
 671                                 }
 672                                 so_rcv->sb_cc = snprintf(so_rcv->sb_data,
 673                                                          so_rcv->sb_datalen,
 674                                                          "%d,%d\r\n", n1, n2);
 675                                 so_rcv->sb_rptr = so_rcv->sb_data;
 676                                 so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 677                         }
 678                         m_free(m);
 679                         return 0;
 680                 }
 681
 682 #if 0
 683          case EMU_RLOGIN:
 684                 /*
 685                  * Rlogin emulation
 686                  * First we accumulate all the initial option negotiation,
 687                  * then fork_exec() rlogin according to the  options
 688                  */
 689                 {
 690                         int i, i2, n;
 691                         char *ptr;
 692                         char args[100];
 693                         char term[100];
 694                         struct sbuf *so_snd = &so->so_snd;
 695                         struct sbuf *so_rcv = &so->so_rcv;
 696
 697                         /* First check if they have a priveladged port, or too much data has arrived */
 698                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 699                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 700                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 701                                 so_snd->sb_wptr += 18;
 702                                 so_snd->sb_cc += 18;
 703                                 tcp_sockclosed(sototcpcb(so));
 704                                 m_free(m);
 705                                 return 0;
 706                         }
 707
 708                         /* Append the current data */
 709                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 710                         so_rcv->sb_wptr += m->m_len;
 711                         so_rcv->sb_rptr += m->m_len;
 712                         m_free(m);
 713
 714                         /*
 715                          * Check if we have all the initial options,
 716                          * and build argument list to rlogin while we're here
 717                          */
 718                         n = 0;
 719                         ptr = so_rcv->sb_data;
 720                         args[0] = 0;
 721                         term[0] = 0;
 722                         while (ptr < so_rcv->sb_wptr) {
 723                                 if (*ptr++ == 0) {
 724                                         n++;
 725                                         if (n == 2) {
 726                                                 sprintf(args, "rlogin -l %s %s",
 727                                                         ptr, inet_ntoa(so->so_faddr));
 728                                         } else if (n == 3) {
 729                                                 i2 = so_rcv->sb_wptr - ptr;
 730                                                 for (i = 0; i < i2; i++) {
 731                                                         if (ptr[i] == '/') {
 732                                                                 ptr[i] = 0;
 733 #ifdef HAVE_SETENV
 734                                                                 sprintf(term, "%s", ptr);
 735 #else
 736                                                                 sprintf(term, "TERM=%s", ptr);
 737 #endif
 738                                                                 ptr[i] = '/';
 739                                                                 break;
 740                                                         }
 741                                                 }
 742                                         }
 743                                 }
 744                         }
 745
 746                         if (n != 4)
 747                            return 0;
 748
 749                         /* We have it, set our term variable and fork_exec() */
 750 #ifdef HAVE_SETENV
 751                         setenv("TERM", term, 1);
 752 #else
 753                         putenv(term);
 754 #endif
 755                         fork_exec(so, args, 2);
 756                         term[0] = 0;
 757                         so->so_emu = 0;
 758
 759                         /* And finally, send the client a 0 character */
 760                         so_snd->sb_wptr[0] = 0;
 761                         so_snd->sb_wptr++;
 762                         so_snd->sb_cc++;
 763
 764                         return 0;
 765                 }
 766
 767          case EMU_RSH:
 768                 /*
 769                  * rsh emulation
 770                  * First we accumulate all the initial option negotiation,
 771                  * then rsh_exec() rsh according to the  options
 772                  */
 773                 {
 774                         int  n;
 775                         char *ptr;
 776                         char *user;
 777                         char *args;
 778                         struct sbuf *so_snd = &so->so_snd;
 779                         struct sbuf *so_rcv = &so->so_rcv;
 780
 781                         /* First check if they have a priveladged port, or too much data has arrived */
 782                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 783                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 784                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 785                                 so_snd->sb_wptr += 18;
 786                                 so_snd->sb_cc += 18;
 787                                 tcp_sockclosed(sototcpcb(so));
 788                                 m_free(m);
 789                                 return 0;
 790                         }
 791
 792                         /* Append the current data */
 793                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 794                         so_rcv->sb_wptr += m->m_len;
 795                         so_rcv->sb_rptr += m->m_len;
 796                         m_free(m);
 797
 798                         /*
 799                          * Check if we have all the initial options,
 800                          * and build argument list to rlogin while we're here
 801                          */
 802                         n = 0;
 803                         ptr = so_rcv->sb_data;
 804                         user="";
 805                         args="";
 806                         if (so->extra==NULL) {
 807                                 struct socket *ns;
 808                                 struct tcpcb* tp;
 809                                 int port=atoi(ptr);
 810                                 if (port <= 0) return 0;
 811                 if (port > 1023 || port < 512) {
 812                   memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 813                   so_snd->sb_wptr += 18;
 814                   so_snd->sb_cc += 18;
 815                   tcp_sockclosed(sototcpcb(so));
 816                   return 0;
 817                 }
 818                                 if ((ns=socreate()) == NULL)
 819                   return 0;
 820                                 if (tcp_attach(ns)<0) {
 821                   free(ns);
 822                   return 0;
 823                                 }
 824
 825                                 ns->so_laddr=so->so_laddr;
 826                                 ns->so_lport=htons(port);
 827
 828                                 (void) tcp_mss(sototcpcb(ns), 0);
 829
 830                                 ns->so_faddr=so->so_faddr;
 831                                 ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */
 832
 833                                 if (ns->so_faddr.s_addr == 0 ||
 834                                         ns->so_faddr.s_addr == loopback_addr.s_addr)
 835                   ns->so_faddr = alias_addr;
 836
 837                                 ns->so_iptos = tcp_tos(ns);
 838                                 tp = sototcpcb(ns);
 839
 840                                 tcp_template(tp);
 841
 842                                 /* Compute window scaling to request.  */
 843                                 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 844                                  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 845                                  *              tp->request_r_scale++;
 846                                  */
 847
 848                 /*soisfconnecting(ns);*/
 849
 850                                 STAT(tcpstat.tcps_connattempt++);
 851
 852                                 tp->t_state = TCPS_SYN_SENT;
 853                                 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 854                                 tp->iss = tcp_iss;
 855                                 tcp_iss += TCP_ISSINCR/2;
 856                                 tcp_sendseqinit(tp);
 857                                 tcp_output(tp);
 858                                 so->extra=ns;
 859                         }
 860                         while (ptr < so_rcv->sb_wptr) {
 861               if (*ptr++ == 0) {
 862                 n++;
 863                 if (n == 2) {
 864                   user=ptr;
 865                 } else if (n == 3) {
 866                   args=ptr;
 867                 }
 868               }
 869                         }
 870
 871                         if (n != 4)
 872               return 0;
 873
 874                         rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
 875                         so->so_emu = 0;
 876                         so->extra=NULL;
 877
 878                         /* And finally, send the client a 0 character */
 879                         so_snd->sb_wptr[0] = 0;
 880                         so_snd->sb_wptr++;
 881                         so_snd->sb_cc++;
 882
 883                         return 0;
 884                 }
 885
 886          case EMU_CTL:
 887                 {
 888                         int num;
 889                         struct sbuf *so_snd = &so->so_snd;
 890                         struct sbuf *so_rcv = &so->so_rcv;
 891
 892                         /*
 893                          * If there is binary data here, we save it in so->so_m
 894                          */
 895                         if (!so->so_m) {
 896                           int rxlen;
 897                           char *rxdata;
 898                           rxdata=mtod(m, char *);
 899                           for (rxlen=m->m_len; rxlen; rxlen--) {
 900                             if (*rxdata++ & 0x80) {
 901                               so->so_m = m;
 902                               return 0;
 903                             }
 904                           }
 905                         } /* if(so->so_m==NULL) */
 906
 907                         /*
 908                          * Append the line
 909                          */
 910                         sbappendsb(so_rcv, m);
 911
 912                         /* To avoid going over the edge of the buffer, we reset it */
 913                         if (so_snd->sb_cc == 0)
 914                            so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;
 915
 916                         /*
 917                          * A bit of a hack:
 918                          * If the first packet we get here is 1 byte long, then it
 919                          * was done in telnet character mode, therefore we must echo
 920                          * the characters as they come.  Otherwise, we echo nothing,
 921                          * because in linemode, the line is already echoed
 922                          * XXX two or more control connections won't work
 923                          */
 924                         if (do_echo == -1) {
 925                                 if (m->m_len == 1) do_echo = 1;
 926                                 else do_echo = 0;
 927                         }
 928                         if (do_echo) {
 929                           sbappendsb(so_snd, m);
 930                           m_free(m);
 931                           tcp_output(sototcpcb(so)); /* XXX */
 932                         } else
 933                           m_free(m);
 934
 935                         num = 0;
 936                         while (num < so->so_rcv.sb_cc) {
 937                                 if (*(so->so_rcv.sb_rptr + num) == '\n' ||
 938                                     *(so->so_rcv.sb_rptr + num) == '\r') {
 939                                         int n;
 940
 941                                         *(so_rcv->sb_rptr + num) = 0;
 942                                         if (ctl_password && !ctl_password_ok) {
 943                                                 /* Need a password */
 944                                                 if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
 945                                                         if (strcmp(buff, ctl_password) == 0) {
 946                                                                 ctl_password_ok = 1;
 947                                                                 n = sprintf(so_snd->sb_wptr,
 948                                                                             "Password OK.\r\n");
 949                                                                 goto do_prompt;
 950                                                         }
 951                                                 }
 952                                                 n = sprintf(so_snd->sb_wptr,
 953                                          "Error: Password required, log on with \"pass PASSWORD\"\r\n");
 954                                                 goto do_prompt;
 955                                         }
 956                                         cfg_quitting = 0;
 957                                         n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
 958                                         if (!cfg_quitting) {
 959                                                 /* Register the printed data */
 960 do_prompt:
 961                                                 so_snd->sb_cc += n;
 962                                                 so_snd->sb_wptr += n;
 963                                                 /* Add prompt */
 964                                                 n = sprintf(so_snd->sb_wptr, "Slirp> ");
 965                                                 so_snd->sb_cc += n;
 966                                                 so_snd->sb_wptr += n;
 967                                         }
 968                                         /* Drop so_rcv data */
 969                                         so_rcv->sb_cc = 0;
 970                                         so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
 971                                         tcp_output(sototcpcb(so)); /* Send the reply */
 972                                 }
 973                                 num++;
 974                         }
 975                         return 0;
 976                 }
 977 #endif
 978         case EMU_FTP: /* ftp */
 979                 *(m->m_data+m->m_len) = 0; /* NULL terminate for strstr */
 980                 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 981                         /*
 982                          * Need to emulate the PORT command
 983                          */
 984                         x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
 985                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 986                         if (x < 6)
 987                            return 1;
 988
 989                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 990                         lport = htons((n5 << 8) | (n6));
 991
 992                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
 993                            return 1;
 994
 995                         n6 = ntohs(so->so_fport);
 996
 997                         n5 = (n6 >> 8) & 0xff;
 998                         n6 &= 0xff;
 999
1000                         laddr = ntohl(so->so_faddr.s_addr);
1001
1002                         n1 = ((laddr >> 24) & 0xff);
1003                         n2 = ((laddr >> 16) & 0xff);
1004                         n3 = ((laddr >> 8)  & 0xff);
1005                         n4 =  (laddr & 0xff);
1006
1007                         m->m_len = bptr - m->m_data; /* Adjust length */
1008                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
1009                                              "ORT %d,%d,%d,%d,%d,%d\r\n%s",
1010                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
1011                         return 1;
1012                 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
1013                         /*
1014                          * Need to emulate the PASV response
1015                          */
1016                         x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
1017                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
1018                         if (x < 6)
1019                            return 1;
1020
1021                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
1022                         lport = htons((n5 << 8) | (n6));
1023
1024                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
1025                            return 1;
1026
1027                         n6 = ntohs(so->so_fport);
1028
1029                         n5 = (n6 >> 8) & 0xff;
1030                         n6 &= 0xff;
1031
1032                         laddr = ntohl(so->so_faddr.s_addr);
1033
1034                         n1 = ((laddr >> 24) & 0xff);
1035                         n2 = ((laddr >> 16) & 0xff);
1036                         n3 = ((laddr >> 8)  & 0xff);
1037                         n4 =  (laddr & 0xff);
1038
1039                         m->m_len = bptr - m->m_data; /* Adjust length */
1040                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
1041                                              "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 = snprintf(m->m_data, m->m_hdr.mh_size, "%d",
1066                                         ntohs(so->so_fport)) + 1;
1067                 return 1;
1068
1069          case EMU_IRC:
1070                 /*
1071                  * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
1072                  */
1073                 *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
1074                 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
1075                          return 1;
1076
1077                 /* The %256s is for the broken mIRC */
1078                 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
1079                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1080                                 return 1;
1081
1082                         m->m_len = bptr - m->m_data; /* Adjust length */
1083                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1084                                              "DCC CHAT chat %lu %u%c\n",
1085                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1086                                              ntohs(so->so_fport), 1);
1087                 } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1088                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1089                                 return 1;
1090
1091                         m->m_len = bptr - m->m_data; /* Adjust length */
1092                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1093                                              "DCC SEND %s %lu %u %u%c\n", buff,
1094                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1095                                              ntohs(so->so_fport), n1, 1);
1096                 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1097                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1098                                 return 1;
1099
1100                         m->m_len = bptr - m->m_data; /* Adjust length */
1101                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1102                                              "DCC MOVE %s %lu %u %u%c\n", buff,
1103                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1104                                              ntohs(so->so_fport), n1, 1);
1105                 }
1106                 return 1;
1107
1108          case EMU_REALAUDIO:
1109                 /*
1110                  * RealAudio emulation - JP. We must try to parse the incoming
1111                  * data and try to find the two characters that contain the
1112                  * port number. Then we redirect an udp port and replace the
1113                  * number with the real port we got.
1114                  *
1115                  * The 1.0 beta versions of the player are not supported
1116                  * any more.
1117                  *
1118                  * A typical packet for player version 1.0 (release version):
1119                  *
1120                  * 0000:50 4E 41 00 05
1121                  * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
1122                  * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
1123                  * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
1124                  * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
1125                  *
1126                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1127                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1128                  * second packet. This time we received five bytes first and
1129                  * then the rest. You never know how many bytes you get.
1130                  *
1131                  * A typical packet for player version 2.0 (beta):
1132                  *
1133                  * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
1134                  * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
1135                  * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
1136                  * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
1137                  * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
1138                  *
1139                  * Port number 0x1BC1 is found at offset 0x0d.
1140                  *
1141                  * This is just a horrible switch statement. Variable ra tells
1142                  * us where we're going.
1143                  */
1144
1145                 bptr = m->m_data;
1146                 while (bptr < m->m_data + m->m_len) {
1147                         u_short p;
1148                         static int ra = 0;
1149                         char ra_tbl[4];
1150
1151                         ra_tbl[0] = 0x50;
1152                         ra_tbl[1] = 0x4e;
1153                         ra_tbl[2] = 0x41;
1154                         ra_tbl[3] = 0;
1155
1156                         switch (ra) {
1157                          case 0:
1158                          case 2:
1159                          case 3:
1160                                 if (*bptr++ != ra_tbl[ra]) {
1161                                         ra = 0;
1162                                         continue;
1163                                 }
1164                                 break;
1165
1166                          case 1:
1167                                 /*
1168                                  * We may get 0x50 several times, ignore them
1169                                  */
1170                                 if (*bptr == 0x50) {
1171                                         ra = 1;
1172                                         bptr++;
1173                                         continue;
1174                                 } else if (*bptr++ != ra_tbl[ra]) {
1175                                         ra = 0;
1176                                         continue;
1177                                 }
1178                                 break;
1179
1180                          case 4:
1181                                 /*
1182                                  * skip version number
1183                                  */
1184                                 bptr++;
1185                                 break;
1186
1187                          case 5:
1188                                 /*
1189                                  * The difference between versions 1.0 and
1190                                  * 2.0 is here. For future versions of
1191                                  * the player this may need to be modified.
1192                                  */
1193                                 if (*(bptr + 1) == 0x02)
1194                                    bptr += 8;
1195                                 else
1196                                    bptr += 4;
1197                                 break;
1198
1199                          case 6:
1200                                 /* This is the field containing the port
1201                                  * number that RA-player is listening to.
1202                                  */
1203                                 lport = (((u_char*)bptr)[0] << 8)
1204                                 + ((u_char *)bptr)[1];
1205                                 if (lport < 6970)
1206                                    lport += 256;   /* don't know why */
1207                                 if (lport < 6970 || lport > 7170)
1208                                    return 1;       /* failed */
1209
1210                                 /* try to get udp port between 6970 - 7170 */
1211                                 for (p = 6970; p < 7071; p++) {
1212                                         if (udp_listen( htons(p),
1213                                                        so->so_laddr.s_addr,
1214                                                        htons(lport),
1215                                                        SS_FACCEPTONCE)) {
1216                                                 break;
1217                                         }
1218                                 }
1219                                 if (p == 7071)
1220                                    p = 0;
1221                                 *(u_char *)bptr++ = (p >> 8) & 0xff;
1222                                 *(u_char *)bptr++ = p & 0xff;
1223                                 ra = 0;
1224                                 return 1;   /* port redirected, we're done */
1225                                 break;
1226
1227                          default:
1228                                 ra = 0;
1229                         }
1230                         ra++;
1231                 }
1232                 return 1;
1233
1234          default:
1235                 /* Ooops, not emulated, won't call tcp_emu again */
1236                 so->so_emu = 0;
1237                 return 1;
1238         }
1239 }
1240
1241 /*
1242  * Do misc. config of SLiRP while its running.
1243  * Return 0 if this connections is to be closed, 1 otherwise,
1244  * return 2 if this is a command-line connection
1245  */
1246 int
1247 tcp_ctl(so)
1248         struct socket *so;
1249 {
1250         struct sbuf *sb = &so->so_snd;
1251         int command;
1252         struct ex_list *ex_ptr;
1253         int do_pty;
1254         //      struct socket *tmpso;
1255
1256         DEBUG_CALL("tcp_ctl");
1257         DEBUG_ARG("so = %lx", (long )so);
1258
1259 #if 0
1260         /*
1261          * Check if they're authorised
1262          */
1263         if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
1264                 sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
1265                 sb->sb_wptr += sb->sb_cc;
1266                 return 0;
1267         }
1268 #endif
1269         command = (ntohl(so->so_faddr.s_addr) & 0xff);
1270
1271         switch(command) {
1272         default: /* Check for exec's */
1273
1274                 /*
1275                  * Check if it's pty_exec
1276                  */
1277                 for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1278                         if (ex_ptr->ex_fport == so->so_fport &&
1279                             command == ex_ptr->ex_addr) {
1280                                 if (ex_ptr->ex_pty == 3) {
1281                                         so->s = -1;
1282                                         so->extra = (void *)ex_ptr->ex_exec;
1283                                         return 1;
1284                                 }
1285                                 do_pty = ex_ptr->ex_pty;
1286                                 goto do_exec;
1287                         }
1288                 }
1289
1290                 /*
1291                  * Nothing bound..
1292                  */
1293                 /* tcp_fconnect(so); */
1294
1295                 /* FALLTHROUGH */
1296         case CTL_ALIAS:
1297           sb->sb_cc = snprintf(sb->sb_wptr, sb->sb_datalen - (sb->sb_wptr - sb->sb_data),
1298                                "Error: No application configured.\r\n");
1299           sb->sb_wptr += sb->sb_cc;
1300           return(0);
1301
1302         do_exec:
1303                 DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
1304                 return(fork_exec(so, ex_ptr->ex_exec, do_pty));
1305
1306 #if 0
1307         case CTL_CMD:
1308            for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
1309              if (tmpso->so_emu == EMU_CTL &&
1310                  !(tmpso->so_tcpcb?
1311                    (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
1312                    :0)) {
1313                /* Ooops, control connection already active */
1314                sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
1315                sb->sb_wptr += sb->sb_cc;
1316                return 0;
1317              }
1318            }
1319            so->so_emu = EMU_CTL;
1320            ctl_password_ok = 0;
1321            sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
1322            sb->sb_wptr += sb->sb_cc;
1323            do_echo=-1;
1324            return(2);
1325 #endif
1326         }
1327 }