qemu/slirp/tcp_subr.c
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   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 "qemu/osdep.h"
  42#include "slirp.h"
  43
  44/* patchable/settable parameters for tcp */
  45/* Don't do rfc1323 performance enhancements */
  46#define TCP_DO_RFC1323 0
  47
  48/*
  49 * Tcp initialization
  50 */
  51void
  52tcp_init(Slirp *slirp)
  53{
  54    slirp->tcp_iss = 1;         /* wrong */
  55    slirp->tcb.so_next = slirp->tcb.so_prev = &slirp->tcb;
  56    slirp->tcp_last_so = &slirp->tcb;
  57}
  58
  59void tcp_cleanup(Slirp *slirp)
  60{
  61    while (slirp->tcb.so_next != &slirp->tcb) {
  62        tcp_close(sototcpcb(slirp->tcb.so_next));
  63    }
  64}
  65
  66/*
  67 * Create template to be used to send tcp packets on a connection.
  68 * Call after host entry created, fills
  69 * in a skeletal tcp/ip header, minimizing the amount of work
  70 * necessary when the connection is used.
  71 */
  72void
  73tcp_template(struct tcpcb *tp)
  74{
  75        struct socket *so = tp->t_socket;
  76        register struct tcpiphdr *n = &tp->t_template;
  77
  78        n->ti_mbuf = NULL;
  79        memset(&n->ti, 0, sizeof(n->ti));
  80        n->ti_x0 = 0;
  81        switch (so->so_ffamily) {
  82        case AF_INET:
  83            n->ti_pr = IPPROTO_TCP;
  84            n->ti_len = htons(sizeof(struct tcphdr));
  85            n->ti_src = so->so_faddr;
  86            n->ti_dst = so->so_laddr;
  87            n->ti_sport = so->so_fport;
  88            n->ti_dport = so->so_lport;
  89            break;
  90
  91        case AF_INET6:
  92            n->ti_nh6 = IPPROTO_TCP;
  93            n->ti_len = htons(sizeof(struct tcphdr));
  94            n->ti_src6 = so->so_faddr6;
  95            n->ti_dst6 = so->so_laddr6;
  96            n->ti_sport = so->so_fport6;
  97            n->ti_dport = so->so_lport6;
  98            break;
  99
 100        default:
 101            g_assert_not_reached();
 102        }
 103
 104        n->ti_seq = 0;
 105        n->ti_ack = 0;
 106        n->ti_x2 = 0;
 107        n->ti_off = 5;
 108        n->ti_flags = 0;
 109        n->ti_win = 0;
 110        n->ti_sum = 0;
 111        n->ti_urp = 0;
 112}
 113
 114/*
 115 * Send a single message to the TCP at address specified by
 116 * the given TCP/IP header.  If m == 0, then we make a copy
 117 * of the tcpiphdr at ti and send directly to the addressed host.
 118 * This is used to force keep alive messages out using the TCP
 119 * template for a connection tp->t_template.  If flags are given
 120 * then we send a message back to the TCP which originated the
 121 * segment ti, and discard the mbuf containing it and any other
 122 * attached mbufs.
 123 *
 124 * In any case the ack and sequence number of the transmitted
 125 * segment are as specified by the parameters.
 126 */
 127void
 128tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
 129            tcp_seq ack, tcp_seq seq, int flags, unsigned short af)
 130{
 131        register int tlen;
 132        int win = 0;
 133
 134        DEBUG_CALL("tcp_respond");
 135        DEBUG_ARG("tp = %p", tp);
 136        DEBUG_ARG("ti = %p", ti);
 137        DEBUG_ARG("m = %p", m);
 138        DEBUG_ARG("ack = %u", ack);
 139        DEBUG_ARG("seq = %u", seq);
 140        DEBUG_ARG("flags = %x", flags);
 141
 142        if (tp)
 143                win = sbspace(&tp->t_socket->so_rcv);
 144        if (m == NULL) {
 145                if (!tp || (m = m_get(tp->t_socket->slirp)) == NULL)
 146                        return;
 147                tlen = 0;
 148                m->m_data += IF_MAXLINKHDR;
 149                *mtod(m, struct tcpiphdr *) = *ti;
 150                ti = mtod(m, struct tcpiphdr *);
 151                memset(&ti->ti, 0, sizeof(ti->ti));
 152                flags = TH_ACK;
 153        } else {
 154                /*
 155                 * ti points into m so the next line is just making
 156                 * the mbuf point to ti
 157                 */
 158                m->m_data = (caddr_t)ti;
 159
 160                m->m_len = sizeof (struct tcpiphdr);
 161                tlen = 0;
 162#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 163                switch (af) {
 164                case AF_INET:
 165                    xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, uint32_t);
 166                    xchg(ti->ti_dport, ti->ti_sport, uint16_t);
 167                    break;
 168                case AF_INET6:
 169                    xchg(ti->ti_dst6, ti->ti_src6, struct in6_addr);
 170                    xchg(ti->ti_dport, ti->ti_sport, uint16_t);
 171                    break;
 172                default:
 173                    g_assert_not_reached();
 174                }
 175#undef xchg
 176        }
 177        ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
 178        tlen += sizeof (struct tcpiphdr);
 179        m->m_len = tlen;
 180
 181        ti->ti_mbuf = NULL;
 182        ti->ti_x0 = 0;
 183        ti->ti_seq = htonl(seq);
 184        ti->ti_ack = htonl(ack);
 185        ti->ti_x2 = 0;
 186        ti->ti_off = sizeof (struct tcphdr) >> 2;
 187        ti->ti_flags = flags;
 188        if (tp)
 189                ti->ti_win = htons((uint16_t) (win >> tp->rcv_scale));
 190        else
 191                ti->ti_win = htons((uint16_t)win);
 192        ti->ti_urp = 0;
 193        ti->ti_sum = 0;
 194        ti->ti_sum = cksum(m, tlen);
 195
 196        struct tcpiphdr tcpiph_save = *(mtod(m, struct tcpiphdr *));
 197        struct ip *ip;
 198        struct ip6 *ip6;
 199
 200        switch (af) {
 201        case AF_INET:
 202            m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
 203                                                 - sizeof(struct ip);
 204            m->m_len  -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
 205                                                 - sizeof(struct ip);
 206            ip = mtod(m, struct ip *);
 207            ip->ip_len = tlen;
 208            ip->ip_dst = tcpiph_save.ti_dst;
 209            ip->ip_src = tcpiph_save.ti_src;
 210            ip->ip_p = tcpiph_save.ti_pr;
 211
 212            if (flags & TH_RST) {
 213                ip->ip_ttl = MAXTTL;
 214            } else {
 215                ip->ip_ttl = IPDEFTTL;
 216            }
 217
 218            ip_output(NULL, m);
 219            break;
 220
 221        case AF_INET6:
 222            m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
 223                                                 - sizeof(struct ip6);
 224            m->m_len  -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
 225                                                 - sizeof(struct ip6);
 226            ip6 = mtod(m, struct ip6 *);
 227            ip6->ip_pl = tlen;
 228            ip6->ip_dst = tcpiph_save.ti_dst6;
 229            ip6->ip_src = tcpiph_save.ti_src6;
 230            ip6->ip_nh = tcpiph_save.ti_nh6;
 231
 232            ip6_output(NULL, m, 0);
 233            break;
 234
 235        default:
 236            g_assert_not_reached();
 237        }
 238}
 239
 240/*
 241 * Create a new TCP control block, making an
 242 * empty reassembly queue and hooking it to the argument
 243 * protocol control block.
 244 */
 245struct tcpcb *
 246tcp_newtcpcb(struct socket *so)
 247{
 248        register struct tcpcb *tp;
 249
 250        tp = (struct tcpcb *)malloc(sizeof(*tp));
 251        if (tp == NULL)
 252                return ((struct tcpcb *)0);
 253
 254        memset((char *) tp, 0, sizeof(struct tcpcb));
 255        tp->seg_next = tp->seg_prev = (struct tcpiphdr*)tp;
 256        tp->t_maxseg = (so->so_ffamily == AF_INET) ? TCP_MSS : TCP6_MSS;
 257
 258        tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
 259        tp->t_socket = so;
 260
 261        /*
 262         * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
 263         * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
 264         * reasonable initial retransmit time.
 265         */
 266        tp->t_srtt = TCPTV_SRTTBASE;
 267        tp->t_rttvar = TCPTV_SRTTDFLT << 2;
 268        tp->t_rttmin = TCPTV_MIN;
 269
 270        TCPT_RANGESET(tp->t_rxtcur,
 271            ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
 272            TCPTV_MIN, TCPTV_REXMTMAX);
 273
 274        tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 275        tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 276        tp->t_state = TCPS_CLOSED;
 277
 278        so->so_tcpcb = tp;
 279
 280        return (tp);
 281}
 282
 283/*
 284 * Drop a TCP connection, reporting
 285 * the specified error.  If connection is synchronized,
 286 * then send a RST to peer.
 287 */
 288struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
 289{
 290        DEBUG_CALL("tcp_drop");
 291        DEBUG_ARG("tp = %p", tp);
 292        DEBUG_ARG("errno = %d", errno);
 293
 294        if (TCPS_HAVERCVDSYN(tp->t_state)) {
 295                tp->t_state = TCPS_CLOSED;
 296                (void) tcp_output(tp);
 297        }
 298        return (tcp_close(tp));
 299}
 300
 301/*
 302 * Close a TCP control block:
 303 *      discard all space held by the tcp
 304 *      discard internet protocol block
 305 *      wake up any sleepers
 306 */
 307struct tcpcb *
 308tcp_close(struct tcpcb *tp)
 309{
 310        register struct tcpiphdr *t;
 311        struct socket *so = tp->t_socket;
 312        Slirp *slirp = so->slirp;
 313        register struct mbuf *m;
 314
 315        DEBUG_CALL("tcp_close");
 316        DEBUG_ARG("tp = %p", tp);
 317
 318        /* free the reassembly queue, if any */
 319        t = tcpfrag_list_first(tp);
 320        while (!tcpfrag_list_end(t, tp)) {
 321                t = tcpiphdr_next(t);
 322                m = tcpiphdr_prev(t)->ti_mbuf;
 323                remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
 324                m_free(m);
 325        }
 326        free(tp);
 327        so->so_tcpcb = NULL;
 328        /* clobber input socket cache if we're closing the cached connection */
 329        if (so == slirp->tcp_last_so)
 330                slirp->tcp_last_so = &slirp->tcb;
 331        closesocket(so->s);
 332        sbfree(&so->so_rcv);
 333        sbfree(&so->so_snd);
 334        sofree(so);
 335        return ((struct tcpcb *)0);
 336}
 337
 338/*
 339 * TCP protocol interface to socket abstraction.
 340 */
 341
 342/*
 343 * User issued close, and wish to trail through shutdown states:
 344 * if never received SYN, just forget it.  If got a SYN from peer,
 345 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 346 * If already got a FIN from peer, then almost done; go to LAST_ACK
 347 * state.  In all other cases, have already sent FIN to peer (e.g.
 348 * after PRU_SHUTDOWN), and just have to play tedious game waiting
 349 * for peer to send FIN or not respond to keep-alives, etc.
 350 * We can let the user exit from the close as soon as the FIN is acked.
 351 */
 352void
 353tcp_sockclosed(struct tcpcb *tp)
 354{
 355
 356        DEBUG_CALL("tcp_sockclosed");
 357        DEBUG_ARG("tp = %p", tp);
 358
 359        if (!tp) {
 360                return;
 361        }
 362
 363        switch (tp->t_state) {
 364
 365        case TCPS_CLOSED:
 366        case TCPS_LISTEN:
 367        case TCPS_SYN_SENT:
 368                tp->t_state = TCPS_CLOSED;
 369                tp = tcp_close(tp);
 370                break;
 371
 372        case TCPS_SYN_RECEIVED:
 373        case TCPS_ESTABLISHED:
 374                tp->t_state = TCPS_FIN_WAIT_1;
 375                break;
 376
 377        case TCPS_CLOSE_WAIT:
 378                tp->t_state = TCPS_LAST_ACK;
 379                break;
 380        }
 381        tcp_output(tp);
 382}
 383
 384/*
 385 * Connect to a host on the Internet
 386 * Called by tcp_input
 387 * Only do a connect, the tcp fields will be set in tcp_input
 388 * return 0 if there's a result of the connect,
 389 * else return -1 means we're still connecting
 390 * The return value is almost always -1 since the socket is
 391 * nonblocking.  Connect returns after the SYN is sent, and does
 392 * not wait for ACK+SYN.
 393 */
 394int tcp_fconnect(struct socket *so, unsigned short af)
 395{
 396  int ret=0;
 397
 398  DEBUG_CALL("tcp_fconnect");
 399  DEBUG_ARG("so = %p", so);
 400
 401  ret = so->s = qemu_socket(af, SOCK_STREAM, 0);
 402  if (ret >= 0) {
 403    int opt, s=so->s;
 404    struct sockaddr_storage addr;
 405
 406    qemu_set_nonblock(s);
 407    socket_set_fast_reuse(s);
 408    opt = 1;
 409    qemu_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt));
 410
 411    addr = so->fhost.ss;
 412    DEBUG_CALL(" connect()ing")
 413    sotranslate_out(so, &addr);
 414
 415    /* We don't care what port we get */
 416    ret = connect(s, (struct sockaddr *)&addr, sockaddr_size(&addr));
 417
 418    /*
 419     * If it's not in progress, it failed, so we just return 0,
 420     * without clearing SS_NOFDREF
 421     */
 422    soisfconnecting(so);
 423  }
 424
 425  return(ret);
 426}
 427
 428/*
 429 * Accept the socket and connect to the local-host
 430 *
 431 * We have a problem. The correct thing to do would be
 432 * to first connect to the local-host, and only if the
 433 * connection is accepted, then do an accept() here.
 434 * But, a) we need to know who's trying to connect
 435 * to the socket to be able to SYN the local-host, and
 436 * b) we are already connected to the foreign host by
 437 * the time it gets to accept(), so... We simply accept
 438 * here and SYN the local-host.
 439 */
 440void tcp_connect(struct socket *inso)
 441{
 442    Slirp *slirp = inso->slirp;
 443    struct socket *so;
 444    struct sockaddr_storage addr;
 445    socklen_t addrlen = sizeof(struct sockaddr_storage);
 446    struct tcpcb *tp;
 447    int s, opt;
 448
 449    DEBUG_CALL("tcp_connect");
 450    DEBUG_ARG("inso = %p", inso);
 451
 452    /*
 453     * If it's an SS_ACCEPTONCE socket, no need to socreate()
 454     * another socket, just use the accept() socket.
 455     */
 456    if (inso->so_state & SS_FACCEPTONCE) {
 457        /* FACCEPTONCE already have a tcpcb */
 458        so = inso;
 459    } else {
 460        so = socreate(slirp);
 461        if (so == NULL) {
 462            /* If it failed, get rid of the pending connection */
 463            closesocket(accept(inso->s, (struct sockaddr *)&addr, &addrlen));
 464            return;
 465        }
 466        if (tcp_attach(so) < 0) {
 467            free(so); /* NOT sofree */
 468            return;
 469        }
 470        so->lhost = inso->lhost;
 471        so->so_ffamily = inso->so_ffamily;
 472    }
 473
 474    tcp_mss(sototcpcb(so), 0);
 475
 476    s = accept(inso->s, (struct sockaddr *)&addr, &addrlen);
 477    if (s < 0) {
 478        tcp_close(sototcpcb(so)); /* This will sofree() as well */
 479        return;
 480    }
 481    qemu_set_nonblock(s);
 482    socket_set_fast_reuse(s);
 483    opt = 1;
 484    qemu_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int));
 485    socket_set_nodelay(s);
 486
 487    so->fhost.ss = addr;
 488    sotranslate_accept(so);
 489
 490    /* Close the accept() socket, set right state */
 491    if (inso->so_state & SS_FACCEPTONCE) {
 492        /* If we only accept once, close the accept() socket */
 493        closesocket(so->s);
 494
 495        /* Don't select it yet, even though we have an FD */
 496        /* if it's not FACCEPTONCE, it's already NOFDREF */
 497        so->so_state = SS_NOFDREF;
 498    }
 499    so->s = s;
 500    so->so_state |= SS_INCOMING;
 501
 502    so->so_iptos = tcp_tos(so);
 503    tp = sototcpcb(so);
 504
 505    tcp_template(tp);
 506
 507    tp->t_state = TCPS_SYN_SENT;
 508    tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
 509    tp->iss = slirp->tcp_iss;
 510    slirp->tcp_iss += TCP_ISSINCR/2;
 511    tcp_sendseqinit(tp);
 512    tcp_output(tp);
 513}
 514
 515/*
 516 * Attach a TCPCB to a socket.
 517 */
 518int
 519tcp_attach(struct socket *so)
 520{
 521        if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
 522           return -1;
 523
 524        insque(so, &so->slirp->tcb);
 525
 526        return 0;
 527}
 528
 529/*
 530 * Set the socket's type of service field
 531 */
 532static const struct tos_t tcptos[] = {
 533          {0, 20, IPTOS_THROUGHPUT, 0}, /* ftp data */
 534          {21, 21, IPTOS_LOWDELAY,  EMU_FTP},   /* ftp control */
 535          {0, 23, IPTOS_LOWDELAY, 0},   /* telnet */
 536          {0, 80, IPTOS_THROUGHPUT, 0}, /* WWW */
 537          {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},   /* rlogin */
 538          {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},      /* shell */
 539          {0, 544, IPTOS_LOWDELAY, EMU_KSH},            /* kshell */
 540          {0, 543, IPTOS_LOWDELAY, 0},  /* klogin */
 541          {0, 6667, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC */
 542          {0, 6668, IPTOS_THROUGHPUT, EMU_IRC}, /* IRC undernet */
 543          {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
 544          {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
 545          {0, 0, 0, 0}
 546};
 547
 548static struct emu_t *tcpemu = NULL;
 549
 550/*
 551 * Return TOS according to the above table
 552 */
 553uint8_t
 554tcp_tos(struct socket *so)
 555{
 556        int i = 0;
 557        struct emu_t *emup;
 558
 559        while(tcptos[i].tos) {
 560                if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
 561                    (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
 562                        so->so_emu = tcptos[i].emu;
 563                        return tcptos[i].tos;
 564                }
 565                i++;
 566        }
 567
 568        /* Nope, lets see if there's a user-added one */
 569        for (emup = tcpemu; emup; emup = emup->next) {
 570                if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
 571                    (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
 572                        so->so_emu = emup->emu;
 573                        return emup->tos;
 574                }
 575        }
 576
 577        return 0;
 578}
 579
 580/*
 581 * Emulate programs that try and connect to us
 582 * This includes ftp (the data connection is
 583 * initiated by the server) and IRC (DCC CHAT and
 584 * DCC SEND) for now
 585 *
 586 * NOTE: It's possible to crash SLiRP by sending it
 587 * unstandard strings to emulate... if this is a problem,
 588 * more checks are needed here
 589 *
 590 * XXX Assumes the whole command came in one packet
 591 *
 592 * XXX Some ftp clients will have their TOS set to
 593 * LOWDELAY and so Nagel will kick in.  Because of this,
 594 * we'll get the first letter, followed by the rest, so
 595 * we simply scan for ORT instead of PORT...
 596 * DCC doesn't have this problem because there's other stuff
 597 * in the packet before the DCC command.
 598 *
 599 * Return 1 if the mbuf m is still valid and should be
 600 * sbappend()ed
 601 *
 602 * NOTE: if you return 0 you MUST m_free() the mbuf!
 603 */
 604int
 605tcp_emu(struct socket *so, struct mbuf *m)
 606{
 607        Slirp *slirp = so->slirp;
 608        u_int n1, n2, n3, n4, n5, n6;
 609        char buff[257];
 610        uint32_t laddr;
 611        u_int lport;
 612        char *bptr;
 613
 614        DEBUG_CALL("tcp_emu");
 615        DEBUG_ARG("so = %p", so);
 616        DEBUG_ARG("m = %p", m);
 617
 618        switch(so->so_emu) {
 619                int x, i;
 620
 621         case EMU_IDENT:
 622                /*
 623                 * Identification protocol as per rfc-1413
 624                 */
 625
 626                {
 627                        struct socket *tmpso;
 628                        struct sockaddr_in addr;
 629                        socklen_t addrlen = sizeof(struct sockaddr_in);
 630                        struct sbuf *so_rcv = &so->so_rcv;
 631
 632                        memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 633                        so_rcv->sb_wptr += m->m_len;
 634                        so_rcv->sb_rptr += m->m_len;
 635                        m->m_data[m->m_len] = 0; /* NULL terminate */
 636                        if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
 637                                if (sscanf(so_rcv->sb_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
 638                                        HTONS(n1);
 639                                        HTONS(n2);
 640                                        /* n2 is the one on our host */
 641                                        for (tmpso = slirp->tcb.so_next;
 642                                             tmpso != &slirp->tcb;
 643                                             tmpso = tmpso->so_next) {
 644                                                if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
 645                                                    tmpso->so_lport == n2 &&
 646                                                    tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
 647                                                    tmpso->so_fport == n1) {
 648                                                        if (getsockname(tmpso->s,
 649                                                                (struct sockaddr *)&addr, &addrlen) == 0)
 650                                                           n2 = ntohs(addr.sin_port);
 651                                                        break;
 652                                                }
 653                                        }
 654                                }
 655                                so_rcv->sb_cc = snprintf(so_rcv->sb_data,
 656                                                         so_rcv->sb_datalen,
 657                                                         "%d,%d\r\n", n1, n2);
 658                                so_rcv->sb_rptr = so_rcv->sb_data;
 659                                so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 660                        }
 661                        m_free(m);
 662                        return 0;
 663                }
 664
 665        case EMU_FTP: /* ftp */
 666                *(m->m_data+m->m_len) = 0; /* NUL terminate for strstr */
 667                if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
 668                        /*
 669                         * Need to emulate the PORT command
 670                         */
 671                        x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]",
 672                                   &n1, &n2, &n3, &n4, &n5, &n6, buff);
 673                        if (x < 6)
 674                           return 1;
 675
 676                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 677                        lport = htons((n5 << 8) | (n6));
 678
 679                        if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr,
 680                                             lport, SS_FACCEPTONCE)) == NULL) {
 681                           return 1;
 682                        }
 683                        n6 = ntohs(so->so_fport);
 684
 685                        n5 = (n6 >> 8) & 0xff;
 686                        n6 &= 0xff;
 687
 688                        laddr = ntohl(so->so_faddr.s_addr);
 689
 690                        n1 = ((laddr >> 24) & 0xff);
 691                        n2 = ((laddr >> 16) & 0xff);
 692                        n3 = ((laddr >> 8)  & 0xff);
 693                        n4 =  (laddr & 0xff);
 694
 695                        m->m_len = bptr - m->m_data; /* Adjust length */
 696                        m->m_len += snprintf(bptr, m->m_size - m->m_len,
 697                                             "ORT %d,%d,%d,%d,%d,%d\r\n%s",
 698                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
 699                        return 1;
 700                } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
 701                        /*
 702                         * Need to emulate the PASV response
 703                         */
 704                        x = sscanf(bptr, "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
 705                                   &n1, &n2, &n3, &n4, &n5, &n6, buff);
 706                        if (x < 6)
 707                           return 1;
 708
 709                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
 710                        lport = htons((n5 << 8) | (n6));
 711
 712                        if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr,
 713                                             lport, SS_FACCEPTONCE)) == NULL) {
 714                           return 1;
 715                        }
 716                        n6 = ntohs(so->so_fport);
 717
 718                        n5 = (n6 >> 8) & 0xff;
 719                        n6 &= 0xff;
 720
 721                        laddr = ntohl(so->so_faddr.s_addr);
 722
 723                        n1 = ((laddr >> 24) & 0xff);
 724                        n2 = ((laddr >> 16) & 0xff);
 725                        n3 = ((laddr >> 8)  & 0xff);
 726                        n4 =  (laddr & 0xff);
 727
 728                        m->m_len = bptr - m->m_data; /* Adjust length */
 729                        m->m_len += snprintf(bptr, m->m_size - m->m_len,
 730                                             "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
 731                                             n1, n2, n3, n4, n5, n6, x==7?buff:"");
 732
 733                        return 1;
 734                }
 735
 736                return 1;
 737
 738         case EMU_KSH:
 739                /*
 740                 * The kshell (Kerberos rsh) and shell services both pass
 741                 * a local port port number to carry signals to the server
 742                 * and stderr to the client.  It is passed at the beginning
 743                 * of the connection as a NUL-terminated decimal ASCII string.
 744                 */
 745                so->so_emu = 0;
 746                for (lport = 0, i = 0; i < m->m_len-1; ++i) {
 747                        if (m->m_data[i] < '0' || m->m_data[i] > '9')
 748                                return 1;       /* invalid number */
 749                        lport *= 10;
 750                        lport += m->m_data[i] - '0';
 751                }
 752                if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
 753                    (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
 754                                     htons(lport), SS_FACCEPTONCE)) != NULL)
 755                    m->m_len = snprintf(m->m_data, m->m_size, "%d",
 756                                        ntohs(so->so_fport)) + 1;
 757                return 1;
 758
 759         case EMU_IRC:
 760                /*
 761                 * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
 762                 */
 763                *(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
 764                if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
 765                         return 1;
 766
 767                /* The %256s is for the broken mIRC */
 768                if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
 769                        if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 770                                             htonl(laddr), htons(lport),
 771                                             SS_FACCEPTONCE)) == NULL) {
 772                                return 1;
 773                        }
 774                        m->m_len = bptr - m->m_data; /* Adjust length */
 775                        m->m_len += snprintf(bptr, m->m_size,
 776                                             "DCC CHAT chat %lu %u%c\n",
 777                                             (unsigned long)ntohl(so->so_faddr.s_addr),
 778                                             ntohs(so->so_fport), 1);
 779                } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
 780                        if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 781                                             htonl(laddr), htons(lport),
 782                                             SS_FACCEPTONCE)) == NULL) {
 783                                return 1;
 784                        }
 785                        m->m_len = bptr - m->m_data; /* Adjust length */
 786                        m->m_len += snprintf(bptr, m->m_size,
 787                                             "DCC SEND %s %lu %u %u%c\n", buff,
 788                                             (unsigned long)ntohl(so->so_faddr.s_addr),
 789                                             ntohs(so->so_fport), n1, 1);
 790                } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
 791                        if ((so = tcp_listen(slirp, INADDR_ANY, 0,
 792                                             htonl(laddr), htons(lport),
 793                                             SS_FACCEPTONCE)) == NULL) {
 794                                return 1;
 795                        }
 796                        m->m_len = bptr - m->m_data; /* Adjust length */
 797                        m->m_len += snprintf(bptr, m->m_size,
 798                                             "DCC MOVE %s %lu %u %u%c\n", buff,
 799                                             (unsigned long)ntohl(so->so_faddr.s_addr),
 800                                             ntohs(so->so_fport), n1, 1);
 801                }
 802                return 1;
 803
 804         case EMU_REALAUDIO:
 805                /*
 806                 * RealAudio emulation - JP. We must try to parse the incoming
 807                 * data and try to find the two characters that contain the
 808                 * port number. Then we redirect an udp port and replace the
 809                 * number with the real port we got.
 810                 *
 811                 * The 1.0 beta versions of the player are not supported
 812                 * any more.
 813                 *
 814                 * A typical packet for player version 1.0 (release version):
 815                 *
 816                 * 0000:50 4E 41 00 05
 817                 * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 ........g.l.c..P
 818                 * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
 819                 * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
 820                 * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
 821                 *
 822                 * Now the port number 0x1BD7 is found at offset 0x04 of the
 823                 * Now the port number 0x1BD7 is found at offset 0x04 of the
 824                 * second packet. This time we received five bytes first and
 825                 * then the rest. You never know how many bytes you get.
 826                 *
 827                 * A typical packet for player version 2.0 (beta):
 828                 *
 829                 * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA.............
 830                 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .gux.c..Win2.0.0
 831                 * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
 832                 * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
 833                 * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
 834                 *
 835                 * Port number 0x1BC1 is found at offset 0x0d.
 836                 *
 837                 * This is just a horrible switch statement. Variable ra tells
 838                 * us where we're going.
 839                 */
 840
 841                bptr = m->m_data;
 842                while (bptr < m->m_data + m->m_len) {
 843                        u_short p;
 844                        static int ra = 0;
 845                        char ra_tbl[4];
 846
 847                        ra_tbl[0] = 0x50;
 848                        ra_tbl[1] = 0x4e;
 849                        ra_tbl[2] = 0x41;
 850                        ra_tbl[3] = 0;
 851
 852                        switch (ra) {
 853                         case 0:
 854                         case 2:
 855                         case 3:
 856                                if (*bptr++ != ra_tbl[ra]) {
 857                                        ra = 0;
 858                                        continue;
 859                                }
 860                                break;
 861
 862                         case 1:
 863                                /*
 864                                 * We may get 0x50 several times, ignore them
 865                                 */
 866                                if (*bptr == 0x50) {
 867                                        ra = 1;
 868                                        bptr++;
 869                                        continue;
 870                                } else if (*bptr++ != ra_tbl[ra]) {
 871                                        ra = 0;
 872                                        continue;
 873                                }
 874                                break;
 875
 876                         case 4:
 877                                /*
 878                                 * skip version number
 879                                 */
 880                                bptr++;
 881                                break;
 882
 883                         case 5:
 884                                /*
 885                                 * The difference between versions 1.0 and
 886                                 * 2.0 is here. For future versions of
 887                                 * the player this may need to be modified.
 888                                 */
 889                                if (*(bptr + 1) == 0x02)
 890                                   bptr += 8;
 891                                else
 892                                   bptr += 4;
 893                                break;
 894
 895                         case 6:
 896                                /* This is the field containing the port
 897                                 * number that RA-player is listening to.
 898                                 */
 899                                lport = (((u_char*)bptr)[0] << 8)
 900                                + ((u_char *)bptr)[1];
 901                                if (lport < 6970)
 902                                   lport += 256;   /* don't know why */
 903                                if (lport < 6970 || lport > 7170)
 904                                   return 1;       /* failed */
 905
 906                                /* try to get udp port between 6970 - 7170 */
 907                                for (p = 6970; p < 7071; p++) {
 908                                        if (udp_listen(slirp, INADDR_ANY,
 909                                                       htons(p),
 910                                                       so->so_laddr.s_addr,
 911                                                       htons(lport),
 912                                                       SS_FACCEPTONCE)) {
 913                                                break;
 914                                        }
 915                                }
 916                                if (p == 7071)
 917                                   p = 0;
 918                                *(u_char *)bptr++ = (p >> 8) & 0xff;
 919                                *(u_char *)bptr = p & 0xff;
 920                                ra = 0;
 921                                return 1;   /* port redirected, we're done */
 922                                break;
 923
 924                         default:
 925                                ra = 0;
 926                        }
 927                        ra++;
 928                }
 929                return 1;
 930
 931         default:
 932                /* Ooops, not emulated, won't call tcp_emu again */
 933                so->so_emu = 0;
 934                return 1;
 935        }
 936}
 937
 938/*
 939 * Do misc. config of SLiRP while its running.
 940 * Return 0 if this connections is to be closed, 1 otherwise,
 941 * return 2 if this is a command-line connection
 942 */
 943int tcp_ctl(struct socket *so)
 944{
 945    Slirp *slirp = so->slirp;
 946    struct sbuf *sb = &so->so_snd;
 947    struct ex_list *ex_ptr;
 948    int do_pty;
 949
 950    DEBUG_CALL("tcp_ctl");
 951    DEBUG_ARG("so = %p", so);
 952
 953    if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
 954        /* Check if it's pty_exec */
 955        for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
 956            if (ex_ptr->ex_fport == so->so_fport &&
 957                so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
 958                if (ex_ptr->ex_pty == 3) {
 959                    so->s = -1;
 960                    so->extra = (void *)ex_ptr->ex_exec;
 961                    return 1;
 962                }
 963                do_pty = ex_ptr->ex_pty;
 964                DEBUG_MISC((dfd, " executing %s\n", ex_ptr->ex_exec));
 965                return fork_exec(so, ex_ptr->ex_exec, do_pty);
 966            }
 967        }
 968    }
 969    sb->sb_cc =
 970        snprintf(sb->sb_wptr, sb->sb_datalen - (sb->sb_wptr - sb->sb_data),
 971                 "Error: No application configured.\r\n");
 972    sb->sb_wptr += sb->sb_cc;
 973    return 0;
 974}
 975