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 #include <slirp.h>
  42
  43 /* patchable/settable parameters for tcp */
  44 /* Don't do rfc1323 performance enhancements */
  45 #define TCP_DO_RFC1323 0
  46
  47 /*
  48  * Tcp initialization
  49  */
  50 void
  51 tcp_init(void)
  52 {
  53         tcp_iss = 1;            /* wrong */
  54         tcb.so_next = tcb.so_prev = &tcb;
  55 }
  56
  57 /*
  58  * Create template to be used to send tcp packets on a connection.
  59  * Call after host entry created, fills
  60  * in a skeletal tcp/ip header, minimizing the amount of work
  61  * necessary when the connection is used.
  62  */
  63 /* struct tcpiphdr * */
  64 void
  65 tcp_template(struct tcpcb *tp)
  66 {
  67         struct socket *so = tp->t_socket;
  68         register struct tcpiphdr *n = &tp->t_template;
  69
  70         n->ti_mbuf = NULL;
  71         n->ti_x1 = 0;
  72         n->ti_pr = IPPROTO_TCP;
  73         n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
  74         n->ti_src = so->so_faddr;
  75         n->ti_dst = so->so_laddr;
  76         n->ti_sport = so->so_fport;
  77         n->ti_dport = so->so_lport;
  78
  79         n->ti_seq = 0;
  80         n->ti_ack = 0;
  81         n->ti_x2 = 0;
  82         n->ti_off = 5;
  83         n->ti_flags = 0;
  84         n->ti_win = 0;
  85         n->ti_sum = 0;
  86         n->ti_urp = 0;
  87 }
  88
  89 /*
  90  * Send a single message to the TCP at address specified by
  91  * the given TCP/IP header.  If m == 0, then we make a copy
  92  * of the tcpiphdr at ti and send directly to the addressed host.
  93  * This is used to force keep alive messages out using the TCP
  94  * template for a connection tp->t_template.  If flags are given
  95  * then we send a message back to the TCP which originated the
  96  * segment ti, and discard the mbuf containing it and any other
  97  * attached mbufs.
  98  *
  99  * In any case the ack and sequence number of the transmitted
 100  * segment are as specified by the parameters.
 101  */
 102 void
 103 tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
 104             tcp_seq ack, tcp_seq seq, int flags)
 105 {
 106         register int tlen;
 107         int win = 0;
 108
 109         DEBUG_CALL("tcp_respond");
 110         DEBUG_ARG("tp = %lx", (long)tp);
 111         DEBUG_ARG("ti = %lx", (long)ti);
 112         DEBUG_ARG("m = %lx", (long)m);
 113         DEBUG_ARG("ack = %u", ack);
 114         DEBUG_ARG("seq = %u", seq);
 115         DEBUG_ARG("flags = %x", flags);
 116
 117         if (tp)
 118                 win = sbspace(&tp->t_socket->so_rcv);
 119         if (m == NULL) {
 120                 if ((m = m_get()) == NULL)
 121                         return;
 122 #ifdef TCP_COMPAT_42
 123                 tlen = 1;
 124 #else
 125                 tlen = 0;
 126 #endif
 127                 m->m_data += IF_MAXLINKHDR;
 128                 *mtod(m, struct tcpiphdr *) = *ti;
 129                 ti = mtod(m, struct tcpiphdr *);
 130                 flags = TH_ACK;
 131         } else {
 132                 /*
 133                  * ti points into m so the next line is just making
 134                  * the mbuf point to ti
 135                  */
 136                 m->m_data = (caddr_t)ti;
 137
 138                 m->m_len = sizeof (struct tcpiphdr);
 139                 tlen = 0;
 140 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 141                 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
 142                 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
 143 #undef xchg
 144         }
 145         ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 146         tlen += sizeof (struct tcpiphdr);
 147         m->m_len = tlen;
 148
 149         ti->ti_mbuf = NULL;
 150         ti->ti_x1 = 0;
 151         ti->ti_seq = htonl(seq);
 152         ti->ti_ack = htonl(ack);
 153         ti->ti_x2 = 0;
 154         ti->ti_off = sizeof (struct tcphdr) >> 2;
 155         ti->ti_flags = flags;
 156         if (tp)
 157                 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
 158         else
 159                 ti->ti_win = htons((u_int16_t)win);
 160         ti->ti_urp = 0;
 161         ti->ti_sum = 0;
 162         ti->ti_sum = cksum(m, tlen);
 163         ((struct ip *)ti)->ip_len = tlen;
 164
 165         if(flags & TH_RST)
 166           ((struct ip *)ti)->ip_ttl = MAXTTL;
 167         else
 168           ((struct ip *)ti)->ip_ttl = IPDEFTTL;
 169
 170         (void) ip_output((struct socket *)0, m);
 171 }
 172
 173 /*
 174  * Create a new TCP control block, making an
 175  * empty reassembly queue and hooking it to the argument
 176  * protocol control block.
 177  */
 178 struct tcpcb *
 179 tcp_newtcpcb(struct socket *so)
 180 {
 181         register struct tcpcb *tp;
 182
 183         tp = (struct tcpcb *)malloc(sizeof(*tp));
 184         if (tp == NULL)
 185                 return ((struct tcpcb *)0);
 186
 187         memset((char *) tp, 0, sizeof(struct tcpcb));
 188         tp->seg_next = tp->seg_prev = (struct tcpiphdr*)tp;
 189         tp->t_maxseg = TCP_MSS;
 190
 191         tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 192         tp->t_socket = so;
 193
 194         /*
 195          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 196          * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 197          * reasonable initial retransmit time.
 198          */
 199         tp->t_srtt = TCPTV_SRTTBASE;
 200         tp->t_rttvar = TCPTV_SRTTDFLT << 2;
 201         tp->t_rttmin = TCPTV_MIN;
 202
 203         TCPT_RANGESET(tp->t_rxtcur,
 204             ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 205             TCPTV_MIN, TCPTV_REXMTMAX);
 206
 207         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 208         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 209         tp->t_state = TCPS_CLOSED;
 210
 211         so->so_tcpcb = tp;
 212
 213         return (tp);
 214 }
 215
 216 /*
 217  * Drop a TCP connection, reporting
 218  * the specified error.  If connection is synchronized,
 219  * then send a RST to peer.
 220  */
 221 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 222 {
 223 /* tcp_drop(tp, errno)
 224         register struct tcpcb *tp;
 225         int errno;
 226 {
 227 */
 228
 229         DEBUG_CALL("tcp_drop");
 230         DEBUG_ARG("tp = %lx", (long)tp);
 231         DEBUG_ARG("errno = %d", errno);
 232
 233         if (TCPS_HAVERCVDSYN(tp->t_state)) {
 234                 tp->t_state = TCPS_CLOSED;
 235                 (void) tcp_output(tp);
 236                 STAT(tcpstat.tcps_drops++);
 237         } else
 238                 STAT(tcpstat.tcps_conndrops++);
 239 /*      if (errno == ETIMEDOUT && tp->t_softerror)
 240  *              errno = tp->t_softerror;
 241  */
 242 /*      so->so_error = errno; */
 243         return (tcp_close(tp));
 244 }
 245
 246 /*
 247  * Close a TCP control block:
 248  *      discard all space held by the tcp
 249  *      discard internet protocol block
 250  *      wake up any sleepers
 251  */
 252 struct tcpcb *
 253 tcp_close(struct tcpcb *tp)
 254 {
 255         register struct tcpiphdr *t;
 256         struct socket *so = tp->t_socket;
 257         register struct mbuf *m;
 258
 259         DEBUG_CALL("tcp_close");
 260         DEBUG_ARG("tp = %lx", (long )tp);
 261
 262         /* free the reassembly queue, if any */
 263         t = tcpfrag_list_first(tp);
 264         while (!tcpfrag_list_end(t, tp)) {
 265                 t = tcpiphdr_next(t);
 266                 m = tcpiphdr_prev(t)->ti_mbuf;
 267                 remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
 268                 m_freem(m);
 269         }
 270         /* It's static */
 271 /*      if (tp->t_template)
 272  *              (void) m_free(dtom(tp->t_template));
 273  */
 274 /*      free(tp, M_PCB);  */
 275         free(tp);
 276         so->so_tcpcb = NULL;
 277         soisfdisconnected(so);
 278         /* clobber input socket cache if we're closing the cached connection */
 279         if (so == tcp_last_so)
 280                 tcp_last_so = &tcb;
 281         closesocket(so->s);
 282         sbfree(&so->so_rcv);
 283         sbfree(&so->so_snd);
 284         sofree(so);
 285         STAT(tcpstat.tcps_closed++);
 286         return ((struct tcpcb *)0);
 287 }
 288
 289 #ifdef notdef
 290 void
 291 tcp_drain()
 292 {
 293         /* XXX */
 294 }
 295
 296 /*
 297  * When a source quench is received, close congestion window
 298  * to one segment.  We will gradually open it again as we proceed.
 299  */
 300 void
 301 tcp_quench(i, errno)
 302
 303         int errno;
 304 {
 305         struct tcpcb *tp = intotcpcb(inp);
 306
 307         if (tp)
 308                 tp->snd_cwnd = tp->t_maxseg;
 309 }
 310
 311 #endif /* notdef */
 312
 313 /*
 314  * TCP protocol interface to socket abstraction.
 315  */
 316
 317 /*
 318  * User issued close, and wish to trail through shutdown states:
 319  * if never received SYN, just forget it.  If got a SYN from peer,
 320  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 321  * If already got a FIN from peer, then almost done; go to LAST_ACK
 322  * state.  In all other cases, have already sent FIN to peer (e.g.
 323  * after PRU_SHUTDOWN), and just have to play tedious game waiting
 324  * for peer to send FIN or not respond to keep-alives, etc.
 325  * We can let the user exit from the close as soon as the FIN is acked.
 326  */
 327 void
 328 tcp_sockclosed(struct tcpcb *tp)
 329 {
 330
 331         DEBUG_CALL("tcp_sockclosed");
 332         DEBUG_ARG("tp = %lx", (long)tp);
 333
 334         switch (tp->t_state) {
 335
 336         case TCPS_CLOSED:
 337         case TCPS_LISTEN:
 338         case TCPS_SYN_SENT:
 339                 tp->t_state = TCPS_CLOSED;
 340                 tp = tcp_close(tp);
 341                 break;
 342
 343         case TCPS_SYN_RECEIVED:
 344         case TCPS_ESTABLISHED:
 345                 tp->t_state = TCPS_FIN_WAIT_1;
 346                 break;
 347
 348         case TCPS_CLOSE_WAIT:
 349                 tp->t_state = TCPS_LAST_ACK;
 350                 break;
 351         }
 352 /*      soisfdisconnecting(tp->t_socket); */
 353         if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
 354                 soisfdisconnected(tp->t_socket);
 355         if (tp)
 356                 tcp_output(tp);
 357 }
 358
 359 /*
 360  * Connect to a host on the Internet
 361  * Called by tcp_input
 362  * Only do a connect, the tcp fields will be set in tcp_input
 363  * return 0 if there's a result of the connect,
 364  * else return -1 means we're still connecting
 365  * The return value is almost always -1 since the socket is
 366  * nonblocking.  Connect returns after the SYN is sent, and does
 367  * not wait for ACK+SYN.
 368  */
 369 int tcp_fconnect(struct socket *so)
 370 {
 371   int ret=0;
 372
 373   DEBUG_CALL("tcp_fconnect");
 374   DEBUG_ARG("so = %lx", (long )so);
 375
 376   if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
 377     int opt, s=so->s;
 378     struct sockaddr_in addr;
 379
 380     fd_nonblock(s);
 381     opt = 1;
 382     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
 383     opt = 1;
 384     setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
 385
 386     addr.sin_family = AF_INET;
 387     if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
 388       /* It's an alias */
 389       switch(ntohl(so->so_faddr.s_addr) & 0xff) {
 390       case CTL_DNS:
 391         addr.sin_addr = dns_addr;
 392         break;
 393       case CTL_ALIAS:
 394       default:
 395         addr.sin_addr = loopback_addr;
 396         break;
 397       }
 398     } else
 399       addr.sin_addr = so->so_faddr;
 400     addr.sin_port = so->so_fport;
 401
 402     DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
 403                 "addr.sin_addr.s_addr=%.16s\n",
 404                 ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
 405     /* We don't care what port we get */
 406     ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
 407
 408     /*
 409      * If it's not in progress, it failed, so we just return 0,
 410      * without clearing SS_NOFDREF
 411      */
 412     soisfconnecting(so);
 413   }
 414
 415   return(ret);
 416 }
 417
 418 /*
 419  * Accept the socket and connect to the local-host
 420  *
 421  * We have a problem. The correct thing to do would be
 422  * to first connect to the local-host, and only if the
 423  * connection is accepted, then do an accept() here.
 424  * But, a) we need to know who's trying to connect
 425  * to the socket to be able to SYN the local-host, and
 426  * b) we are already connected to the foreign host by
 427  * the time it gets to accept(), so... We simply accept
 428  * here and SYN the local-host.
 429  */
 430 void
 431 tcp_connect(struct socket *inso)
 432 {
 433         struct socket *so;
 434         struct sockaddr_in addr;
 435         socklen_t addrlen = sizeof(struct sockaddr_in);
 436         struct tcpcb *tp;
 437         int s, opt;
 438
 439         DEBUG_CALL("tcp_connect");
 440         DEBUG_ARG("inso = %lx", (long)inso);
 441
 442         /*
 443          * If it's an SS_ACCEPTONCE socket, no need to socreate()
 444          * another socket, just use the accept() socket.
 445          */
 446         if (inso->so_state & SS_FACCEPTONCE) {
 447                 /* FACCEPTONCE already have a tcpcb */
 448                 so = inso;
 449         } else {
 450                 if ((so = socreate()) == NULL) {
 451                         /* If it failed, get rid of the pending connection */
 452                         closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
 453                         return;
 454                 }
 455                 if (tcp_attach(so) < 0) {
 456                         free(so); /* NOT sofree */
 457                         return;
 458                 }
 459                 so->so_laddr = inso->so_laddr;
 460                 so->so_lport = inso->so_lport;
 461         }
 462
 463         (void) tcp_mss(sototcpcb(so), 0);
 464
 465         if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
 466                 tcp_close(sototcpcb(so)); /* This will sofree() as well */
 467                 return;
 468         }
 469         fd_nonblock(s);
 470         opt = 1;
 471         setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 472         opt = 1;
 473         setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
 474         opt = 1;
 475         setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));
 476
 477         so->so_fport = addr.sin_port;
 478         so->so_faddr = addr.sin_addr;
 479         /* Translate connections from localhost to the real hostname */
 480         if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
 481            so->so_faddr = alias_addr;
 482
 483         /* Close the accept() socket, set right state */
 484         if (inso->so_state & SS_FACCEPTONCE) {
 485                 closesocket(so->s); /* If we only accept once, close the accept() socket */
 486                 so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
 487                                            /* if it's not FACCEPTONCE, it's already NOFDREF */
 488         }
 489         so->s = s;
 490
 491         so->so_iptos = tcp_tos(so);
 492         tp = sototcpcb(so);
 493
 494         tcp_template(tp);
 495
 496         /* Compute window scaling to request.  */
 497 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 498  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 499  *              tp->request_r_scale++;
 500  */
 501
 502 /*      soisconnecting(so); */ /* NOFDREF used instead */
 503         STAT(tcpstat.tcps_connattempt++);
 504
 505         tp->t_state = TCPS_SYN_SENT;
 506         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 507         tp->iss = tcp_iss;
 508         tcp_iss += TCP_ISSINCR/2;
 509         tcp_sendseqinit(tp);
 510         tcp_output(tp);
 511 }
 512
 513 /*
 514  * Attach a TCPCB to a socket.
 515  */
 516 int
 517 tcp_attach(struct socket *so)
 518 {
 519         if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 520            return -1;
 521
 522         insque(so, &tcb);
 523
 524         return 0;
 525 }
 526
 527 /*
 528  * Set the socket's type of service field
 529  */
 530 static const struct tos_t tcptos[] = {
 531           {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 532           {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 533           {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 534           {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 535           {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 536           {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 537           {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 538           {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 539           {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 540           {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 541           {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 542           {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 543           {0, 0, 0, 0}
 544 };
 545
 546 #ifdef CONFIG_QEMU
 547 static
 548 #endif
 549 struct emu_t *tcpemu = NULL;
 550
 551 /*
 552  * Return TOS according to the above table
 553  */
 554 u_int8_t
 555 tcp_tos(struct socket *so)
 556 {
 557         int i = 0;
 558         struct emu_t *emup;
 559
 560         while(tcptos[i].tos) {
 561                 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 562                     (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 563                         so->so_emu = tcptos[i].emu;
 564                         return tcptos[i].tos;
 565                 }
 566                 i++;
 567         }
 568
 569         /* Nope, lets see if there's a user-added one */
 570         for (emup = tcpemu; emup; emup = emup->next) {
 571                 if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 572                     (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 573                         so->so_emu = emup->emu;
 574                         return emup->tos;
 575                 }
 576         }
 577
 578         return 0;
 579 }
 580
 581 #if 0
 582 int do_echo = -1;
 583 #endif
 584
 585 /*
 586  * Emulate programs that try and connect to us
 587  * This includes ftp (the data connection is
 588  * initiated by the server) and IRC (DCC CHAT and
 589  * DCC SEND) for now
 590  *
 591  * NOTE: It's possible to crash SLiRP by sending it
 592  * unstandard strings to emulate... if this is a problem,
 593  * more checks are needed here
 594  *
 595  * XXX Assumes the whole command came in one packet
 596  *
 597  * XXX Some ftp clients will have their TOS set to
 598  * LOWDELAY and so Nagel will kick in.  Because of this,
 599  * we'll get the first letter, followed by the rest, so
 600  * we simply scan for ORT instead of PORT...
 601  * DCC doesn't have this problem because there's other stuff
 602  * in the packet before the DCC command.
 603  *
 604  * Return 1 if the mbuf m is still valid and should be
 605  * sbappend()ed
 606  *
 607  * NOTE: if you return 0 you MUST m_free() the mbuf!
 608  */
 609 int
 610 tcp_emu(struct socket *so, struct mbuf *m)
 611 {
 612         u_int n1, n2, n3, n4, n5, n6;
 613         char buff[257];
 614         u_int32_t laddr;
 615         u_int lport;
 616         char *bptr;
 617
 618         DEBUG_CALL("tcp_emu");
 619         DEBUG_ARG("so = %lx", (long)so);
 620         DEBUG_ARG("m = %lx", (long)m);
 621
 622         switch(so->so_emu) {
 623                 int x, i;
 624
 625          case EMU_IDENT:
 626                 /*
 627                  * Identification protocol as per rfc-1413
 628                  */
 629
 630                 {
 631                         struct socket *tmpso;
 632                         struct sockaddr_in addr;
 633                         socklen_t addrlen = sizeof(struct sockaddr_in);
 634                         struct sbuf *so_rcv = &so->so_rcv;
 635
 636                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 637                         so_rcv->sb_wptr += m->m_len;
 638                         so_rcv->sb_rptr += m->m_len;
 639                         m->m_data[m->m_len] = 0; /* NULL terminate */
 640                         if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 641                                 if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
 642                                         HTONS(n1);
 643                                         HTONS(n2);
 644                                         /* n2 is the one on our host */
 645                                         for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
 646                                                 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 647                                                     tmpso->so_lport == n2 &&
 648                                                     tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 649                                                     tmpso->so_fport == n1) {
 650                                                         if (getsockname(tmpso->s,
 651                                                                 (struct sockaddr *)&addr, &addrlen) == 0)
 652                                                            n2 = ntohs(addr.sin_port);
 653                                                         break;
 654                                                 }
 655                                         }
 656                                 }
 657                                 so_rcv->sb_cc = snprintf(so_rcv->sb_data,
 658                                                          so_rcv->sb_datalen,
 659                                                          "%d,%d\r\n", n1, n2);
 660                                 so_rcv->sb_rptr = so_rcv->sb_data;
 661                                 so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 662                         }
 663                         m_free(m);
 664                         return 0;
 665                 }
 666
 667 #if 0
 668          case EMU_RLOGIN:
 669                 /*
 670                  * Rlogin emulation
 671                  * First we accumulate all the initial option negotiation,
 672                  * then fork_exec() rlogin according to the  options
 673                  */
 674                 {
 675                         int i, i2, n;
 676                         char *ptr;
 677                         char args[100];
 678                         char term[100];
 679                         struct sbuf *so_snd = &so->so_snd;
 680                         struct sbuf *so_rcv = &so->so_rcv;
 681
 682                         /* First check if they have a priveladged port, or too much data has arrived */
 683                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 684                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 685                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 686                                 so_snd->sb_wptr += 18;
 687                                 so_snd->sb_cc += 18;
 688                                 tcp_sockclosed(sototcpcb(so));
 689                                 m_free(m);
 690                                 return 0;
 691                         }
 692
 693                         /* Append the current data */
 694                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 695                         so_rcv->sb_wptr += m->m_len;
 696                         so_rcv->sb_rptr += m->m_len;
 697                         m_free(m);
 698
 699                         /*
 700                          * Check if we have all the initial options,
 701                          * and build argument list to rlogin while we're here
 702                          */
 703                         n = 0;
 704                         ptr = so_rcv->sb_data;
 705                         args[0] = 0;
 706                         term[0] = 0;
 707                         while (ptr < so_rcv->sb_wptr) {
 708                                 if (*ptr++ == 0) {
 709                                         n++;
 710                                         if (n == 2) {
 711                                                 sprintf(args, "rlogin -l %s %s",
 712                                                         ptr, inet_ntoa(so->so_faddr));
 713                                         } else if (n == 3) {
 714                                                 i2 = so_rcv->sb_wptr - ptr;
 715                                                 for (i = 0; i < i2; i++) {
 716                                                         if (ptr[i] == '/') {
 717                                                                 ptr[i] = 0;
 718 #ifdef HAVE_SETENV
 719                                                                 sprintf(term, "%s", ptr);
 720 #else
 721                                                                 sprintf(term, "TERM=%s", ptr);
 722 #endif
 723                                                                 ptr[i] = '/';
 724                                                                 break;
 725                                                         }
 726                                                 }
 727                                         }
 728                                 }
 729                         }
 730
 731                         if (n != 4)
 732                            return 0;
 733
 734                         /* We have it, set our term variable and fork_exec() */
 735 #ifdef HAVE_SETENV
 736                         setenv("TERM", term, 1);
 737 #else
 738                         putenv(term);
 739 #endif
 740                         fork_exec(so, args, 2);
 741                         term[0] = 0;
 742                         so->so_emu = 0;
 743
 744                         /* And finally, send the client a 0 character */
 745                         so_snd->sb_wptr[0] = 0;
 746                         so_snd->sb_wptr++;
 747                         so_snd->sb_cc++;
 748
 749                         return 0;
 750                 }
 751
 752          case EMU_RSH:
 753                 /*
 754                  * rsh emulation
 755                  * First we accumulate all the initial option negotiation,
 756                  * then rsh_exec() rsh according to the  options
 757                  */
 758                 {
 759                         int  n;
 760                         char *ptr;
 761                         char *user;
 762                         char *args;
 763                         struct sbuf *so_snd = &so->so_snd;
 764                         struct sbuf *so_rcv = &so->so_rcv;
 765
 766                         /* First check if they have a priveladged port, or too much data has arrived */
 767                         if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
 768                             (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
 769                                 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 770                                 so_snd->sb_wptr += 18;
 771                                 so_snd->sb_cc += 18;
 772                                 tcp_sockclosed(sototcpcb(so));
 773                                 m_free(m);
 774                                 return 0;
 775                         }
 776
 777                         /* Append the current data */
 778                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 779                         so_rcv->sb_wptr += m->m_len;
 780                         so_rcv->sb_rptr += m->m_len;
 781                         m_free(m);
 782
 783                         /*
 784                          * Check if we have all the initial options,
 785                          * and build argument list to rlogin while we're here
 786                          */
 787                         n = 0;
 788                         ptr = so_rcv->sb_data;
 789                         user="";
 790                         args="";
 791                         if (so->extra==NULL) {
 792                                 struct socket *ns;
 793                                 struct tcpcb* tp;
 794                                 int port=atoi(ptr);
 795                                 if (port <= 0) return 0;
 796                 if (port > 1023 || port < 512) {
 797                   memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
 798                   so_snd->sb_wptr += 18;
 799                   so_snd->sb_cc += 18;
 800                   tcp_sockclosed(sototcpcb(so));
 801                   return 0;
 802                 }
 803                                 if ((ns=socreate()) == NULL)
 804                   return 0;
 805                                 if (tcp_attach(ns)<0) {
 806                   free(ns);
 807                   return 0;
 808                                 }
 809
 810                                 ns->so_laddr=so->so_laddr;
 811                                 ns->so_lport=htons(port);
 812
 813                                 (void) tcp_mss(sototcpcb(ns), 0);
 814
 815                                 ns->so_faddr=so->so_faddr;
 816                                 ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */
 817
 818                                 if (ns->so_faddr.s_addr == 0 ||
 819                                         ns->so_faddr.s_addr == loopback_addr.s_addr)
 820                   ns->so_faddr = alias_addr;
 821
 822                                 ns->so_iptos = tcp_tos(ns);
 823                                 tp = sototcpcb(ns);
 824
 825                                 tcp_template(tp);
 826
 827                                 /* Compute window scaling to request.  */
 828                                 /*      while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 829                                  *              (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 830                                  *              tp->request_r_scale++;
 831                                  */
 832
 833                 /*soisfconnecting(ns);*/
 834
 835                                 STAT(tcpstat.tcps_connattempt++);
 836
 837                                 tp->t_state = TCPS_SYN_SENT;
 838                                 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 839                                 tp->iss = tcp_iss;
 840                                 tcp_iss += TCP_ISSINCR/2;
 841                                 tcp_sendseqinit(tp);
 842                                 tcp_output(tp);
 843                                 so->extra=ns;
 844                         }
 845                         while (ptr < so_rcv->sb_wptr) {
 846               if (*ptr++ == 0) {
 847                 n++;
 848                 if (n == 2) {
 849                   user=ptr;
 850                 } else if (n == 3) {
 851                   args=ptr;
 852                 }
 853               }
 854                         }
 855
 856                         if (n != 4)
 857               return 0;
 858
 859                         rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
 860                         so->so_emu = 0;
 861                         so->extra=NULL;
 862
 863                         /* And finally, send the client a 0 character */
 864                         so_snd->sb_wptr[0] = 0;
 865                         so_snd->sb_wptr++;
 866                         so_snd->sb_cc++;
 867
 868                         return 0;
 869                 }
 870
 871          case EMU_CTL:
 872                 {
 873                         int num;
 874                         struct sbuf *so_snd = &so->so_snd;
 875                         struct sbuf *so_rcv = &so->so_rcv;
 876
 877                         /*
 878                          * If there is binary data here, we save it in so->so_m
 879                          */
 880                         if (!so->so_m) {
 881                           int rxlen;
 882                           char *rxdata;
 883                           rxdata=mtod(m, char *);
 884                           for (rxlen=m->m_len; rxlen; rxlen--) {
 885                             if (*rxdata++ & 0x80) {
 886                               so->so_m = m;
 887                               return 0;
 888                             }
 889                           }
 890                         } /* if(so->so_m==NULL) */
 891
 892                         /*
 893                          * Append the line
 894                          */
 895                         sbappendsb(so_rcv, m);
 896
 897                         /* To avoid going over the edge of the buffer, we reset it */
 898                         if (so_snd->sb_cc == 0)
 899                            so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;
 900
 901                         /*
 902                          * A bit of a hack:
 903                          * If the first packet we get here is 1 byte long, then it
 904                          * was done in telnet character mode, therefore we must echo
 905                          * the characters as they come.  Otherwise, we echo nothing,
 906                          * because in linemode, the line is already echoed
 907                          * XXX two or more control connections won't work
 908                          */
 909                         if (do_echo == -1) {
 910                                 if (m->m_len == 1) do_echo = 1;
 911                                 else do_echo = 0;
 912                         }
 913                         if (do_echo) {
 914                           sbappendsb(so_snd, m);
 915                           m_free(m);
 916                           tcp_output(sototcpcb(so)); /* XXX */
 917                         } else
 918                           m_free(m);
 919
 920                         num = 0;
 921                         while (num < so->so_rcv.sb_cc) {
 922                                 if (*(so->so_rcv.sb_rptr + num) == '\n' ||
 923                                     *(so->so_rcv.sb_rptr + num) == '\r') {
 924                                         int n;
 925
 926                                         *(so_rcv->sb_rptr + num) = 0;
 927                                         if (ctl_password && !ctl_password_ok) {
 928                                                 /* Need a password */
 929                                                 if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
 930                                                         if (strcmp(buff, ctl_password) == 0) {
 931                                                                 ctl_password_ok = 1;
 932                                                                 n = sprintf(so_snd->sb_wptr,
 933                                                                             "Password OK.\r\n");
 934                                                                 goto do_prompt;
 935                                                         }
 936                                                 }
 937                                                 n = sprintf(so_snd->sb_wptr,
 938                                          "Error: Password required, log on with \"pass PASSWORD\"\r\n");
 939                                                 goto do_prompt;
 940                                         }
 941                                         cfg_quitting = 0;
 942                                         n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
 943                                         if (!cfg_quitting) {
 944                                                 /* Register the printed data */
 945 do_prompt:
 946                                                 so_snd->sb_cc += n;
 947                                                 so_snd->sb_wptr += n;
 948                                                 /* Add prompt */
 949                                                 n = sprintf(so_snd->sb_wptr, "Slirp> ");
 950                                                 so_snd->sb_cc += n;
 951                                                 so_snd->sb_wptr += n;
 952                                         }
 953                                         /* Drop so_rcv data */
 954                                         so_rcv->sb_cc = 0;
 955                                         so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
 956                                         tcp_output(sototcpcb(so)); /* Send the reply */
 957                                 }
 958                                 num++;
 959                         }
 960                         return 0;
 961                 }
 962 #endif
 963         case EMU_FTP: /* ftp */
 964                 *(m->m_data+m->m_len) = 0; /* NUL terminate for strstr */
 965                 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 966                         /*
 967                          * Need to emulate the PORT command
 968                          */
 969                         x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
 970                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 971                         if (x < 6)
 972                            return 1;
 973
 974                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 975                         lport = htons((n5 << 8) | (n6));
 976
 977                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
 978                            return 1;
 979
 980                         n6 = ntohs(so->so_fport);
 981
 982                         n5 = (n6 >> 8) & 0xff;
 983                         n6 &= 0xff;
 984
 985                         laddr = ntohl(so->so_faddr.s_addr);
 986
 987                         n1 = ((laddr >> 24) & 0xff);
 988                         n2 = ((laddr >> 16) & 0xff);
 989                         n3 = ((laddr >> 8)  & 0xff);
 990                         n4 =  (laddr & 0xff);
 991
 992                         m->m_len = bptr - m->m_data; /* Adjust length */
 993                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
 994                                              "ORT %d,%d,%d,%d,%d,%d\r\n%s",
 995                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 996                         return 1;
 997                 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
 998                         /*
 999                          * Need to emulate the PASV response
1000                          */
1001                         x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
1002                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
1003                         if (x < 6)
1004                            return 1;
1005
1006                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
1007                         lport = htons((n5 << 8) | (n6));
1008
1009                         if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
1010                            return 1;
1011
1012                         n6 = ntohs(so->so_fport);
1013
1014                         n5 = (n6 >> 8) & 0xff;
1015                         n6 &= 0xff;
1016
1017                         laddr = ntohl(so->so_faddr.s_addr);
1018
1019                         n1 = ((laddr >> 24) & 0xff);
1020                         n2 = ((laddr >> 16) & 0xff);
1021                         n3 = ((laddr >> 8)  & 0xff);
1022                         n4 =  (laddr & 0xff);
1023
1024                         m->m_len = bptr - m->m_data; /* Adjust length */
1025                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
1026                                              "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
1027                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
1028
1029                         return 1;
1030                 }
1031
1032                 return 1;
1033
1034          case EMU_KSH:
1035                 /*
1036                  * The kshell (Kerberos rsh) and shell services both pass
1037                  * a local port port number to carry signals to the server
1038                  * and stderr to the client.  It is passed at the beginning
1039                  * of the connection as a NUL-terminated decimal ASCII string.
1040                  */
1041                 so->so_emu = 0;
1042                 for (lport = 0, i = 0; i < m->m_len-1; ++i) {
1043                         if (m->m_data[i] < '0' || m->m_data[i] > '9')
1044                                 return 1;       /* invalid number */
1045                         lport *= 10;
1046                         lport += m->m_data[i] - '0';
1047                 }
1048                 if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
1049                     (so = solisten(0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
1050                     m->m_len = snprintf(m->m_data, m->m_hdr.mh_size, "%d",
1051                                         ntohs(so->so_fport)) + 1;
1052                 return 1;
1053
1054          case EMU_IRC:
1055                 /*
1056                  * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
1057                  */
1058                 *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
1059                 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
1060                          return 1;
1061
1062                 /* The %256s is for the broken mIRC */
1063                 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
1064                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1065                                 return 1;
1066
1067                         m->m_len = bptr - m->m_data; /* Adjust length */
1068                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1069                                              "DCC CHAT chat %lu %u%c\n",
1070                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1071                                              ntohs(so->so_fport), 1);
1072                 } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1073                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1074                                 return 1;
1075
1076                         m->m_len = bptr - m->m_data; /* Adjust length */
1077                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1078                                              "DCC SEND %s %lu %u %u%c\n", buff,
1079                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1080                                              ntohs(so->so_fport), n1, 1);
1081                 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
1082                         if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
1083                                 return 1;
1084
1085                         m->m_len = bptr - m->m_data; /* Adjust length */
1086                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
1087                                              "DCC MOVE %s %lu %u %u%c\n", buff,
1088                                              (unsigned long)ntohl(so->so_faddr.s_addr),
1089                                              ntohs(so->so_fport), n1, 1);
1090                 }
1091                 return 1;
1092
1093          case EMU_REALAUDIO:
1094                 /*
1095                  * RealAudio emulation - JP. We must try to parse the incoming
1096                  * data and try to find the two characters that contain the
1097                  * port number. Then we redirect an udp port and replace the
1098                  * number with the real port we got.
1099                  *
1100                  * The 1.0 beta versions of the player are not supported
1101                  * any more.
1102                  *
1103                  * A typical packet for player version 1.0 (release version):
1104                  *
1105                  * 0000:50 4E 41 00 05
1106                  * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
1107                  * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
1108                  * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
1109                  * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
1110                  *
1111                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1112                  * Now the port number 0x1BD7 is found at offset 0x04 of the
1113                  * second packet. This time we received five bytes first and
1114                  * then the rest. You never know how many bytes you get.
1115                  *
1116                  * A typical packet for player version 2.0 (beta):
1117                  *
1118                  * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
1119                  * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
1120                  * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
1121                  * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
1122                  * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
1123                  *
1124                  * Port number 0x1BC1 is found at offset 0x0d.
1125                  *
1126                  * This is just a horrible switch statement. Variable ra tells
1127                  * us where we're going.
1128                  */
1129
1130                 bptr = m->m_data;
1131                 while (bptr < m->m_data + m->m_len) {
1132                         u_short p;
1133                         static int ra = 0;
1134                         char ra_tbl[4];
1135
1136                         ra_tbl[0] = 0x50;
1137                         ra_tbl[1] = 0x4e;
1138                         ra_tbl[2] = 0x41;
1139                         ra_tbl[3] = 0;
1140
1141                         switch (ra) {
1142                          case 0:
1143                          case 2:
1144                          case 3:
1145                                 if (*bptr++ != ra_tbl[ra]) {
1146                                         ra = 0;
1147                                         continue;
1148                                 }
1149                                 break;
1150
1151                          case 1:
1152                                 /*
1153                                  * We may get 0x50 several times, ignore them
1154                                  */
1155                                 if (*bptr == 0x50) {
1156                                         ra = 1;
1157                                         bptr++;
1158                                         continue;
1159                                 } else if (*bptr++ != ra_tbl[ra]) {
1160                                         ra = 0;
1161                                         continue;
1162                                 }
1163                                 break;
1164
1165                          case 4:
1166                                 /*
1167                                  * skip version number
1168                                  */
1169                                 bptr++;
1170                                 break;
1171
1172                          case 5:
1173                                 /*
1174                                  * The difference between versions 1.0 and
1175                                  * 2.0 is here. For future versions of
1176                                  * the player this may need to be modified.
1177                                  */
1178                                 if (*(bptr + 1) == 0x02)
1179                                    bptr += 8;
1180                                 else
1181                                    bptr += 4;
1182                                 break;
1183
1184                          case 6:
1185                                 /* This is the field containing the port
1186                                  * number that RA-player is listening to.
1187                                  */
1188                                 lport = (((u_char*)bptr)[0] << 8)
1189                                 + ((u_char *)bptr)[1];
1190                                 if (lport < 6970)
1191                                    lport += 256;   /* don't know why */
1192                                 if (lport < 6970 || lport > 7170)
1193                                    return 1;       /* failed */
1194
1195                                 /* try to get udp port between 6970 - 7170 */
1196                                 for (p = 6970; p < 7071; p++) {
1197                                         if (udp_listen( htons(p),
1198                                                        so->so_laddr.s_addr,
1199                                                        htons(lport),
1200                                                        SS_FACCEPTONCE)) {
1201                                                 break;
1202                                         }
1203                                 }
1204                                 if (p == 7071)
1205                                    p = 0;
1206                                 *(u_char *)bptr++ = (p >> 8) & 0xff;
1207                                 *(u_char *)bptr++ = p & 0xff;
1208                                 ra = 0;
1209                                 return 1;   /* port redirected, we're done */
1210                                 break;
1211
1212                          default:
1213                                 ra = 0;
1214                         }
1215                         ra++;
1216                 }
1217                 return 1;
1218
1219          default:
1220                 /* Ooops, not emulated, won't call tcp_emu again */
1221                 so->so_emu = 0;
1222                 return 1;
1223         }
1224 }
1225
1226 /*
1227  * Do misc. config of SLiRP while its running.
1228  * Return 0 if this connections is to be closed, 1 otherwise,
1229  * return 2 if this is a command-line connection
1230  */
1231 int
1232 tcp_ctl(struct socket *so)
1233 {
1234         struct sbuf *sb = &so->so_snd;
1235         int command;
1236         struct ex_list *ex_ptr;
1237         int do_pty;
1238         //      struct socket *tmpso;
1239
1240         DEBUG_CALL("tcp_ctl");
1241         DEBUG_ARG("so = %lx", (long )so);
1242
1243 #if 0
1244         /*
1245          * Check if they're authorised
1246          */
1247         if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
1248                 sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
1249                 sb->sb_wptr += sb->sb_cc;
1250                 return 0;
1251         }
1252 #endif
1253         command = (ntohl(so->so_faddr.s_addr) & 0xff);
1254
1255         switch(command) {
1256         default: /* Check for exec's */
1257
1258                 /*
1259                  * Check if it's pty_exec
1260                  */
1261                 for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1262                         if (ex_ptr->ex_fport == so->so_fport &&
1263                             command == ex_ptr->ex_addr) {
1264                                 if (ex_ptr->ex_pty == 3) {
1265                                         so->s = -1;
1266                                         so->extra = (void *)ex_ptr->ex_exec;
1267                                         return 1;
1268                                 }
1269                                 do_pty = ex_ptr->ex_pty;
1270                                 goto do_exec;
1271                         }
1272                 }
1273
1274                 /*
1275                  * Nothing bound..
1276                  */
1277                 /* tcp_fconnect(so); */
1278
1279                 /* FALLTHROUGH */
1280         case CTL_ALIAS:
1281           sb->sb_cc = snprintf(sb->sb_wptr, sb->sb_datalen - (sb->sb_wptr - sb->sb_data),
1282                                "Error: No application configured.\r\n");
1283           sb->sb_wptr += sb->sb_cc;
1284           return(0);
1285
1286         do_exec:
1287                 DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
1288                 return(fork_exec(so, ex_ptr->ex_exec, do_pty));
1289
1290 #if 0
1291         case CTL_CMD:
1292            for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
1293              if (tmpso->so_emu == EMU_CTL &&
1294                  !(tmpso->so_tcpcb?
1295                    (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
1296                    :0)) {
1297                /* Ooops, control connection already active */
1298                sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
1299                sb->sb_wptr += sb->sb_cc;
1300                return 0;
1301              }
1302            }
1303            so->so_emu = EMU_CTL;
1304            ctl_password_ok = 0;
1305            sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
1306            sb->sb_wptr += sb->sb_cc;
1307            do_echo=-1;
1308            return(2);
1309 #endif
1310         }
1311 }