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(Slirp *slirp)
  52 {
  53     slirp->tcp_iss = 1;         /* wrong */
  54     slirp->tcb.so_next = slirp->tcb.so_prev = &slirp->tcb;
  55     slirp->tcp_last_so = &slirp->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 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(tp->t_socket->slirp)) == NULL)
 121                         return;
 122                 tlen = 0;
 123                 m->m_data += IF_MAXLINKHDR;
 124                 *mtod(m, struct tcpiphdr *) = *ti;
 125                 ti = mtod(m, struct tcpiphdr *);
 126                 flags = TH_ACK;
 127         } else {
 128                 /*
 129                  * ti points into m so the next line is just making
 130                  * the mbuf point to ti
 131                  */
 132                 m->m_data = (caddr_t)ti;
 133
 134                 m->m_len = sizeof (struct tcpiphdr);
 135                 tlen = 0;
 136 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 137                 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
 138                 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
 139 #undef xchg
 140         }
 141         ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 142         tlen += sizeof (struct tcpiphdr);
 143         m->m_len = tlen;
 144
 145         ti->ti_mbuf = NULL;
 146         ti->ti_x1 = 0;
 147         ti->ti_seq = htonl(seq);
 148         ti->ti_ack = htonl(ack);
 149         ti->ti_x2 = 0;
 150         ti->ti_off = sizeof (struct tcphdr) >> 2;
 151         ti->ti_flags = flags;
 152         if (tp)
 153                 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
 154         else
 155                 ti->ti_win = htons((u_int16_t)win);
 156         ti->ti_urp = 0;
 157         ti->ti_sum = 0;
 158         ti->ti_sum = cksum(m, tlen);
 159         ((struct ip *)ti)->ip_len = tlen;
 160
 161         if(flags & TH_RST)
 162           ((struct ip *)ti)->ip_ttl = MAXTTL;
 163         else
 164           ((struct ip *)ti)->ip_ttl = IPDEFTTL;
 165
 166         (void) ip_output((struct socket *)0, m);
 167 }
 168
 169 /*
 170  * Create a new TCP control block, making an
 171  * empty reassembly queue and hooking it to the argument
 172  * protocol control block.
 173  */
 174 struct tcpcb *
 175 tcp_newtcpcb(struct socket *so)
 176 {
 177         register struct tcpcb *tp;
 178
 179         tp = (struct tcpcb *)malloc(sizeof(*tp));
 180         if (tp == NULL)
 181                 return ((struct tcpcb *)0);
 182
 183         memset((char *) tp, 0, sizeof(struct tcpcb));
 184         tp->seg_next = tp->seg_prev = (struct tcpiphdr*)tp;
 185         tp->t_maxseg = TCP_MSS;
 186
 187         tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 188         tp->t_socket = so;
 189
 190         /*
 191          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 192          * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 193          * reasonable initial retransmit time.
 194          */
 195         tp->t_srtt = TCPTV_SRTTBASE;
 196         tp->t_rttvar = TCPTV_SRTTDFLT << 2;
 197         tp->t_rttmin = TCPTV_MIN;
 198
 199         TCPT_RANGESET(tp->t_rxtcur,
 200             ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 201             TCPTV_MIN, TCPTV_REXMTMAX);
 202
 203         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 204         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 205         tp->t_state = TCPS_CLOSED;
 206
 207         so->so_tcpcb = tp;
 208
 209         return (tp);
 210 }
 211
 212 /*
 213  * Drop a TCP connection, reporting
 214  * the specified error.  If connection is synchronized,
 215  * then send a RST to peer.
 216  */
 217 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 218 {
 219         DEBUG_CALL("tcp_drop");
 220         DEBUG_ARG("tp = %lx", (long)tp);
 221         DEBUG_ARG("errno = %d", errno);
 222
 223         if (TCPS_HAVERCVDSYN(tp->t_state)) {
 224                 tp->t_state = TCPS_CLOSED;
 225                 (void) tcp_output(tp);
 226         }
 227         return (tcp_close(tp));
 228 }
 229
 230 /*
 231  * Close a TCP control block:
 232  *      discard all space held by the tcp
 233  *      discard internet protocol block
 234  *      wake up any sleepers
 235  */
 236 struct tcpcb *
 237 tcp_close(struct tcpcb *tp)
 238 {
 239         register struct tcpiphdr *t;
 240         struct socket *so = tp->t_socket;
 241         Slirp *slirp = so->slirp;
 242         register struct mbuf *m;
 243
 244         DEBUG_CALL("tcp_close");
 245         DEBUG_ARG("tp = %lx", (long )tp);
 246
 247         /* free the reassembly queue, if any */
 248         t = tcpfrag_list_first(tp);
 249         while (!tcpfrag_list_end(t, tp)) {
 250                 t = tcpiphdr_next(t);
 251                 m = tcpiphdr_prev(t)->ti_mbuf;
 252                 remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
 253                 m_freem(m);
 254         }
 255         free(tp);
 256         so->so_tcpcb = NULL;
 257         /* clobber input socket cache if we're closing the cached connection */
 258         if (so == slirp->tcp_last_so)
 259                 slirp->tcp_last_so = &slirp->tcb;
 260         closesocket(so->s);
 261         sbfree(&so->so_rcv);
 262         sbfree(&so->so_snd);
 263         sofree(so);
 264         return ((struct tcpcb *)0);
 265 }
 266
 267 /*
 268  * TCP protocol interface to socket abstraction.
 269  */
 270
 271 /*
 272  * User issued close, and wish to trail through shutdown states:
 273  * if never received SYN, just forget it.  If got a SYN from peer,
 274  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 275  * If already got a FIN from peer, then almost done; go to LAST_ACK
 276  * state.  In all other cases, have already sent FIN to peer (e.g.
 277  * after PRU_SHUTDOWN), and just have to play tedious game waiting
 278  * for peer to send FIN or not respond to keep-alives, etc.
 279  * We can let the user exit from the close as soon as the FIN is acked.
 280  */
 281 void
 282 tcp_sockclosed(struct tcpcb *tp)
 283 {
 284
 285         DEBUG_CALL("tcp_sockclosed");
 286         DEBUG_ARG("tp = %lx", (long)tp);
 287
 288         switch (tp->t_state) {
 289
 290         case TCPS_CLOSED:
 291         case TCPS_LISTEN:
 292         case TCPS_SYN_SENT:
 293                 tp->t_state = TCPS_CLOSED;
 294                 tp = tcp_close(tp);
 295                 break;
 296
 297         case TCPS_SYN_RECEIVED:
 298         case TCPS_ESTABLISHED:
 299                 tp->t_state = TCPS_FIN_WAIT_1;
 300                 break;
 301
 302         case TCPS_CLOSE_WAIT:
 303                 tp->t_state = TCPS_LAST_ACK;
 304                 break;
 305         }
 306         if (tp)
 307                 tcp_output(tp);
 308 }
 309
 310 /*
 311  * Connect to a host on the Internet
 312  * Called by tcp_input
 313  * Only do a connect, the tcp fields will be set in tcp_input
 314  * return 0 if there's a result of the connect,
 315  * else return -1 means we're still connecting
 316  * The return value is almost always -1 since the socket is
 317  * nonblocking.  Connect returns after the SYN is sent, and does
 318  * not wait for ACK+SYN.
 319  */
 320 int tcp_fconnect(struct socket *so)
 321 {
 322   Slirp *slirp = so->slirp;
 323   int ret=0;
 324
 325   DEBUG_CALL("tcp_fconnect");
 326   DEBUG_ARG("so = %lx", (long )so);
 327
 328   if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
 329     int opt, s=so->s;
 330     struct sockaddr_in addr;
 331
 332     fd_nonblock(s);
 333     opt = 1;
 334     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
 335     opt = 1;
 336     setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
 337
 338     addr.sin_family = AF_INET;
 339     if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
 340         slirp->vnetwork_addr.s_addr) {
 341       /* It's an alias */
 342       if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
 343         addr.sin_addr = dns_addr;
 344       } else {
 345         addr.sin_addr = loopback_addr;
 346       }
 347     } else
 348       addr.sin_addr = so->so_faddr;
 349     addr.sin_port = so->so_fport;
 350
 351     DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
 352                 "addr.sin_addr.s_addr=%.16s\n",
 353                 ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
 354     /* We don't care what port we get */
 355     ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
 356
 357     /*
 358      * If it's not in progress, it failed, so we just return 0,
 359      * without clearing SS_NOFDREF
 360      */
 361     soisfconnecting(so);
 362   }
 363
 364   return(ret);
 365 }
 366
 367 /*
 368  * Accept the socket and connect to the local-host
 369  *
 370  * We have a problem. The correct thing to do would be
 371  * to first connect to the local-host, and only if the
 372  * connection is accepted, then do an accept() here.
 373  * But, a) we need to know who's trying to connect
 374  * to the socket to be able to SYN the local-host, and
 375  * b) we are already connected to the foreign host by
 376  * the time it gets to accept(), so... We simply accept
 377  * here and SYN the local-host.
 378  */
 379 void
 380 tcp_connect(struct socket *inso)
 381 {
 382         Slirp *slirp = inso->slirp;
 383         struct socket *so;
 384         struct sockaddr_in addr;
 385         socklen_t addrlen = sizeof(struct sockaddr_in);
 386         struct tcpcb *tp;
 387         int s, opt;
 388
 389         DEBUG_CALL("tcp_connect");
 390         DEBUG_ARG("inso = %lx", (long)inso);
 391
 392         /*
 393          * If it's an SS_ACCEPTONCE socket, no need to socreate()
 394          * another socket, just use the accept() socket.
 395          */
 396         if (inso->so_state & SS_FACCEPTONCE) {
 397                 /* FACCEPTONCE already have a tcpcb */
 398                 so = inso;
 399         } else {
 400                 if ((so = socreate(slirp)) == NULL) {
 401                         /* If it failed, get rid of the pending connection */
 402                         closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
 403                         return;
 404                 }
 405                 if (tcp_attach(so) < 0) {
 406                         free(so); /* NOT sofree */
 407                         return;
 408                 }
 409                 so->so_laddr = inso->so_laddr;
 410                 so->so_lport = inso->so_lport;
 411         }
 412
 413         (void) tcp_mss(sototcpcb(so), 0);
 414
 415         if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
 416                 tcp_close(sototcpcb(so)); /* This will sofree() as well */
 417                 return;
 418         }
 419         fd_nonblock(s);
 420         opt = 1;
 421         setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
 422         opt = 1;
 423         setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
 424         opt = 1;
 425         setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));
 426
 427         so->so_fport = addr.sin_port;
 428         so->so_faddr = addr.sin_addr;
 429         /* Translate connections from localhost to the real hostname */
 430         if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
 431            so->so_faddr = slirp->vhost_addr;
 432
 433         /* Close the accept() socket, set right state */
 434         if (inso->so_state & SS_FACCEPTONCE) {
 435                 closesocket(so->s); /* If we only accept once, close the accept() socket */
 436                 so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
 437                                            /* if it's not FACCEPTONCE, it's already NOFDREF */
 438         }
 439         so->s = s;
 440         so->so_state |= SS_INCOMING;
 441
 442         so->so_iptos = tcp_tos(so);
 443         tp = sototcpcb(so);
 444
 445         tcp_template(tp);
 446
 447         tp->t_state = TCPS_SYN_SENT;
 448         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 449         tp->iss = slirp->tcp_iss;
 450         slirp->tcp_iss += TCP_ISSINCR/2;
 451         tcp_sendseqinit(tp);
 452         tcp_output(tp);
 453 }
 454
 455 /*
 456  * Attach a TCPCB to a socket.
 457  */
 458 int
 459 tcp_attach(struct socket *so)
 460 {
 461         if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 462            return -1;
 463
 464         insque(so, &so->slirp->tcb);
 465
 466         return 0;
 467 }
 468
 469 /*
 470  * Set the socket's type of service field
 471  */
 472 static const struct tos_t tcptos[] = {
 473           {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 474           {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 475           {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 476           {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 477           {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 478           {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 479           {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 480           {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 481           {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 482           {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 483           {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 484           {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 485           {0, 0, 0, 0}
 486 };
 487
 488 static struct emu_t *tcpemu = NULL;
 489
 490 /*
 491  * Return TOS according to the above table
 492  */
 493 u_int8_t
 494 tcp_tos(struct socket *so)
 495 {
 496         int i = 0;
 497         struct emu_t *emup;
 498
 499         while(tcptos[i].tos) {
 500                 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 501                     (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 502                         so->so_emu = tcptos[i].emu;
 503                         return tcptos[i].tos;
 504                 }
 505                 i++;
 506         }
 507
 508         /* Nope, lets see if there's a user-added one */
 509         for (emup = tcpemu; emup; emup = emup->next) {
 510                 if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 511                     (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 512                         so->so_emu = emup->emu;
 513                         return emup->tos;
 514                 }
 515         }
 516
 517         return 0;
 518 }
 519
 520 /*
 521  * Emulate programs that try and connect to us
 522  * This includes ftp (the data connection is
 523  * initiated by the server) and IRC (DCC CHAT and
 524  * DCC SEND) for now
 525  *
 526  * NOTE: It's possible to crash SLiRP by sending it
 527  * unstandard strings to emulate... if this is a problem,
 528  * more checks are needed here
 529  *
 530  * XXX Assumes the whole command came in one packet
 531  *
 532  * XXX Some ftp clients will have their TOS set to
 533  * LOWDELAY and so Nagel will kick in.  Because of this,
 534  * we'll get the first letter, followed by the rest, so
 535  * we simply scan for ORT instead of PORT...
 536  * DCC doesn't have this problem because there's other stuff
 537  * in the packet before the DCC command.
 538  *
 539  * Return 1 if the mbuf m is still valid and should be
 540  * sbappend()ed
 541  *
 542  * NOTE: if you return 0 you MUST m_free() the mbuf!
 543  */
 544 int
 545 tcp_emu(struct socket *so, struct mbuf *m)
 546 {
 547         Slirp *slirp = so->slirp;
 548         u_int n1, n2, n3, n4, n5, n6;
 549         char buff[257];
 550         u_int32_t laddr;
 551         u_int lport;
 552         char *bptr;
 553
 554         DEBUG_CALL("tcp_emu");
 555         DEBUG_ARG("so = %lx", (long)so);
 556         DEBUG_ARG("m = %lx", (long)m);
 557
 558         switch(so->so_emu) {
 559                 int x, i;
 560
 561          case EMU_IDENT:
 562                 /*
 563                  * Identification protocol as per rfc-1413
 564                  */
 565
 566                 {
 567                         struct socket *tmpso;
 568                         struct sockaddr_in addr;
 569                         socklen_t addrlen = sizeof(struct sockaddr_in);
 570                         struct sbuf *so_rcv = &so->so_rcv;
 571
 572                         memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 573                         so_rcv->sb_wptr += m->m_len;
 574                         so_rcv->sb_rptr += m->m_len;
 575                         m->m_data[m->m_len] = 0; /* NULL terminate */
 576                         if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 577                                 if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
 578                                         HTONS(n1);
 579                                         HTONS(n2);
 580                                         /* n2 is the one on our host */
 581                                         for (tmpso = slirp->tcb.so_next;
 582                                              tmpso != &slirp->tcb;
 583                                              tmpso = tmpso->so_next) {
 584                                                 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 585                                                     tmpso->so_lport == n2 &&
 586                                                     tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 587                                                     tmpso->so_fport == n1) {
 588                                                         if (getsockname(tmpso->s,
 589                                                                 (struct sockaddr *)&addr, &addrlen) == 0)
 590                                                            n2 = ntohs(addr.sin_port);
 591                                                         break;
 592                                                 }
 593                                         }
 594                                 }
 595                                 so_rcv->sb_cc = snprintf(so_rcv->sb_data,
 596                                                          so_rcv->sb_datalen,
 597                                                          "%d,%d\r\n", n1, n2);
 598                                 so_rcv->sb_rptr = so_rcv->sb_data;
 599                                 so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 600                         }
 601                         m_free(m);
 602                         return 0;
 603                 }
 604
 605         case EMU_FTP: /* ftp */
 606                 *(m->m_data+m->m_len) = 0; /* NUL terminate for strstr */
 607                 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 608                         /*
 609                          * Need to emulate the PORT command
 610                          */
 611                         x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
 612                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 613                         if (x < 6)
 614                            return 1;
 615
 616                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 617                         lport = htons((n5 << 8) | (n6));
 618
 619                         if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr,
 620                                              lport, SS_FACCEPTONCE)) == NULL) {
 621                            return 1;
 622                         }
 623                         n6 = ntohs(so->so_fport);
 624
 625                         n5 = (n6 >> 8) & 0xff;
 626                         n6 &= 0xff;
 627
 628                         laddr = ntohl(so->so_faddr.s_addr);
 629
 630                         n1 = ((laddr >> 24) & 0xff);
 631                         n2 = ((laddr >> 16) & 0xff);
 632                         n3 = ((laddr >> 8)  & 0xff);
 633                         n4 =  (laddr & 0xff);
 634
 635                         m->m_len = bptr - m->m_data; /* Adjust length */
 636                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
 637                                              "ORT %d,%d,%d,%d,%d,%d\r\n%s",
 638                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 639                         return 1;
 640                 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
 641                         /*
 642                          * Need to emulate the PASV response
 643                          */
 644                         x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
 645                                    &n1, &n2, &n3, &n4, &n5, &n6, buff);
 646                         if (x < 6)
 647                            return 1;
 648
 649                         laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 650                         lport = htons((n5 << 8) | (n6));
 651
 652                         if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr,
 653                                              lport, SS_FACCEPTONCE)) == NULL) {
 654                            return 1;
 655                         }
 656                         n6 = ntohs(so->so_fport);
 657
 658                         n5 = (n6 >> 8) & 0xff;
 659                         n6 &= 0xff;
 660
 661                         laddr = ntohl(so->so_faddr.s_addr);
 662
 663                         n1 = ((laddr >> 24) & 0xff);
 664                         n2 = ((laddr >> 16) & 0xff);
 665                         n3 = ((laddr >> 8)  & 0xff);
 666                         n4 =  (laddr & 0xff);
 667
 668                         m->m_len = bptr - m->m_data; /* Adjust length */
 669                         m->m_len += snprintf(bptr, m->m_hdr.mh_size - m->m_len,
 670                                              "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
 671                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 672
 673                         return 1;
 674                 }
 675
 676                 return 1;
 677
 678          case EMU_KSH:
 679                 /*
 680                  * The kshell (Kerberos rsh) and shell services both pass
 681                  * a local port port number to carry signals to the server
 682                  * and stderr to the client.  It is passed at the beginning
 683                  * of the connection as a NUL-terminated decimal ASCII string.
 684                  */
 685                 so->so_emu = 0;
 686                 for (lport = 0, i = 0; i < m->m_len-1; ++i) {
 687                         if (m->m_data[i] < '0' || m->m_data[i] > '9')
 688                                 return 1;       /* invalid number */
 689                         lport *= 10;
 690                         lport += m->m_data[i] - '0';
 691                 }
 692                 if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
 693                     (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
 694                                      htons(lport), SS_FACCEPTONCE)) != NULL)
 695                     m->m_len = snprintf(m->m_data, m->m_hdr.mh_size, "%d",
 696                                         ntohs(so->so_fport)) + 1;
 697                 return 1;
 698
 699          case EMU_IRC:
 700                 /*
 701                  * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
 702                  */
 703                 *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
 704                 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
 705                          return 1;
 706
 707                 /* The %256s is for the broken mIRC */
 708                 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
 709                         if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 710                                              htonl(laddr), htons(lport),
 711                                              SS_FACCEPTONCE)) == NULL) {
 712                                 return 1;
 713                         }
 714                         m->m_len = bptr - m->m_data; /* Adjust length */
 715                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
 716                                              "DCC CHAT chat %lu %u%c\n",
 717                                              (unsigned long)ntohl(so->so_faddr.s_addr),
 718                                              ntohs(so->so_fport), 1);
 719                 } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
 720                         if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 721                                              htonl(laddr), htons(lport),
 722                                              SS_FACCEPTONCE)) == NULL) {
 723                                 return 1;
 724                         }
 725                         m->m_len = bptr - m->m_data; /* Adjust length */
 726                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
 727                                              "DCC SEND %s %lu %u %u%c\n", buff,
 728                                              (unsigned long)ntohl(so->so_faddr.s_addr),
 729                                              ntohs(so->so_fport), n1, 1);
 730                 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
 731                         if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 732                                              htonl(laddr), htons(lport),
 733                                              SS_FACCEPTONCE)) == NULL) {
 734                                 return 1;
 735                         }
 736                         m->m_len = bptr - m->m_data; /* Adjust length */
 737                         m->m_len += snprintf(bptr, m->m_hdr.mh_size,
 738                                              "DCC MOVE %s %lu %u %u%c\n", buff,
 739                                              (unsigned long)ntohl(so->so_faddr.s_addr),
 740                                              ntohs(so->so_fport), n1, 1);
 741                 }
 742                 return 1;
 743
 744          case EMU_REALAUDIO:
 745                 /*
 746                  * RealAudio emulation - JP. We must try to parse the incoming
 747                  * data and try to find the two characters that contain the
 748                  * port number. Then we redirect an udp port and replace the
 749                  * number with the real port we got.
 750                  *
 751                  * The 1.0 beta versions of the player are not supported
 752                  * any more.
 753                  *
 754                  * A typical packet for player version 1.0 (release version):
 755                  *
 756                  * 0000:50 4E 41 00 05
 757                  * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 ........g.l.c..P
 758                  * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
 759                  * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
 760                  * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
 761                  *
 762                  * Now the port number 0x1BD7 is found at offset 0x04 of the
 763                  * Now the port number 0x1BD7 is found at offset 0x04 of the
 764                  * second packet. This time we received five bytes first and
 765                  * then the rest. You never know how many bytes you get.
 766                  *
 767                  * A typical packet for player version 2.0 (beta):
 768                  *
 769                  * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA.............
 770                  * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .gux.c..Win2.0.0
 771                  * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
 772                  * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
 773                  * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
 774                  *
 775                  * Port number 0x1BC1 is found at offset 0x0d.
 776                  *
 777                  * This is just a horrible switch statement. Variable ra tells
 778                  * us where we're going.
 779                  */
 780
 781                 bptr = m->m_data;
 782                 while (bptr < m->m_data + m->m_len) {
 783                         u_short p;
 784                         static int ra = 0;
 785                         char ra_tbl[4];
 786
 787                         ra_tbl[0] = 0x50;
 788                         ra_tbl[1] = 0x4e;
 789                         ra_tbl[2] = 0x41;
 790                         ra_tbl[3] = 0;
 791
 792                         switch (ra) {
 793                          case 0:
 794                          case 2:
 795                          case 3:
 796                                 if (*bptr++ != ra_tbl[ra]) {
 797                                         ra = 0;
 798                                         continue;
 799                                 }
 800                                 break;
 801
 802                          case 1:
 803                                 /*
 804                                  * We may get 0x50 several times, ignore them
 805                                  */
 806                                 if (*bptr == 0x50) {
 807                                         ra = 1;
 808                                         bptr++;
 809                                         continue;
 810                                 } else if (*bptr++ != ra_tbl[ra]) {
 811                                         ra = 0;
 812                                         continue;
 813                                 }
 814                                 break;
 815
 816                          case 4:
 817                                 /*
 818                                  * skip version number
 819                                  */
 820                                 bptr++;
 821                                 break;
 822
 823                          case 5:
 824                                 /*
 825                                  * The difference between versions 1.0 and
 826                                  * 2.0 is here. For future versions of
 827                                  * the player this may need to be modified.
 828                                  */
 829                                 if (*(bptr + 1) == 0x02)
 830                                    bptr += 8;
 831                                 else
 832                                    bptr += 4;
 833                                 break;
 834
 835                          case 6:
 836                                 /* This is the field containing the port
 837                                  * number that RA-player is listening to.
 838                                  */
 839                                 lport = (((u_char*)bptr)[0] << 8)
 840                                 + ((u_char *)bptr)[1];
 841                                 if (lport < 6970)
 842                                    lport += 256;   /* don't know why */
 843                                 if (lport < 6970 || lport > 7170)
 844                                    return 1;       /* failed */
 845
 846                                 /* try to get udp port between 6970 - 7170 */
 847                                 for (p = 6970; p < 7071; p++) {
 848                                         if (udp_listen(slirp, INADDR_ANY,
 849                                                        htons(p),
 850                                                        so->so_laddr.s_addr,
 851                                                        htons(lport),
 852                                                        SS_FACCEPTONCE)) {
 853                                                 break;
 854                                         }
 855                                 }
 856                                 if (p == 7071)
 857                                    p = 0;
 858                                 *(u_char *)bptr++ = (p >> 8) & 0xff;
 859                                 *(u_char *)bptr++ = p & 0xff;
 860                                 ra = 0;
 861                                 return 1;   /* port redirected, we're done */
 862                                 break;
 863
 864                          default:
 865                                 ra = 0;
 866                         }
 867                         ra++;
 868                 }
 869                 return 1;
 870
 871          default:
 872                 /* Ooops, not emulated, won't call tcp_emu again */
 873                 so->so_emu = 0;
 874                 return 1;
 875         }
 876 }
 877
 878 /*
 879  * Do misc. config of SLiRP while its running.
 880  * Return 0 if this connections is to be closed, 1 otherwise,
 881  * return 2 if this is a command-line connection
 882  */
 883 int tcp_ctl(struct socket *so)
 884 {
 885     Slirp *slirp = so->slirp;
 886     struct sbuf *sb = &so->so_snd;
 887     struct ex_list *ex_ptr;
 888     int do_pty;
 889
 890     DEBUG_CALL("tcp_ctl");
 891     DEBUG_ARG("so = %lx", (long )so);
 892
 893     if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
 894         /* Check if it's pty_exec */
 895         for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
 896             if (ex_ptr->ex_fport == so->so_fport &&
 897                 so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
 898                 if (ex_ptr->ex_pty == 3) {
 899                     so->s = -1;
 900                     so->extra = (void *)ex_ptr->ex_exec;
 901                     return 1;
 902                 }
 903                 do_pty = ex_ptr->ex_pty;
 904                 DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
 905                 return fork_exec(so, ex_ptr->ex_exec, do_pty);
 906             }
 907         }
 908     }
 909     sb->sb_cc =
 910         snprintf(sb->sb_wptr, sb->sb_datalen - (sb->sb_wptr - sb->sb_data),
 911                  "Error: No application configured.\r\n");
 912     sb->sb_wptr += sb->sb_cc;
 913     return 0;
 914 }