1 /* SPDX-License-Identifier: BSD-3-Clause */
2 /*
3 * Copyright (c) 1982, 1986, 1988, 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
31 * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
32 */
33
34 /*
35 * Changes and additions relating to SLiRP
36 * Copyright (c) 1995 Danny Gasparovski.
37 */
38
39 #include "slirp.h"
40
41 /* patchable/settable parameters for tcp */
42 /* Don't do rfc1323 performance enhancements */
43 #define TCP_DO_RFC1323 0
44
45 /*
46 * Tcp initialization
47 */
tcp_init(Slirp * slirp)48 void tcp_init(Slirp *slirp)
49 {
50 slirp->tcp_iss = 1; /* wrong */
51 slirp->tcb.so_next = slirp->tcb.so_prev = &slirp->tcb;
52 slirp->tcp_last_so = &slirp->tcb;
53 }
54
tcp_cleanup(Slirp * slirp)55 void tcp_cleanup(Slirp *slirp)
56 {
57 while (slirp->tcb.so_next != &slirp->tcb) {
58 tcp_close(sototcpcb(slirp->tcb.so_next));
59 }
60 }
61
62 /*
63 * Create template to be used to send tcp packets on a connection.
64 * Call after host entry created, fills
65 * in a skeletal tcp/ip header, minimizing the amount of work
66 * necessary when the connection is used.
67 */
tcp_template(struct tcpcb * tp)68 void tcp_template(struct tcpcb *tp)
69 {
70 struct socket *so = tp->t_socket;
71 register struct tcpiphdr *n = &tp->t_template;
72
73 n->ti_mbuf = NULL;
74 memset(&n->ti, 0, sizeof(n->ti));
75 n->ti_x0 = 0;
76 switch (so->so_ffamily) {
77 case AF_INET:
78 n->ti_pr = IPPROTO_TCP;
79 n->ti_len = htons(sizeof(struct tcphdr));
80 n->ti_src = so->so_faddr;
81 n->ti_dst = so->so_laddr;
82 n->ti_sport = so->so_fport;
83 n->ti_dport = so->so_lport;
84 break;
85
86 case AF_INET6:
87 n->ti_nh6 = IPPROTO_TCP;
88 n->ti_len = htons(sizeof(struct tcphdr));
89 n->ti_src6 = so->so_faddr6;
90 n->ti_dst6 = so->so_laddr6;
91 n->ti_sport = so->so_fport6;
92 n->ti_dport = so->so_lport6;
93 break;
94
95 default:
96 g_assert_not_reached();
97 }
98
99 n->ti_seq = 0;
100 n->ti_ack = 0;
101 n->ti_x2 = 0;
102 n->ti_off = 5;
103 n->ti_flags = 0;
104 n->ti_win = 0;
105 n->ti_sum = 0;
106 n->ti_urp = 0;
107 }
108
109 /*
110 * Send a single message to the TCP at address specified by
111 * the given TCP/IP header. If m == 0, then we make a copy
112 * of the tcpiphdr at ti and send directly to the addressed host.
113 * This is used to force keep alive messages out using the TCP
114 * template for a connection tp->t_template. If flags are given
115 * then we send a message back to the TCP which originated the
116 * segment ti, and discard the mbuf containing it and any other
117 * attached mbufs.
118 *
119 * In any case the ack and sequence number of the transmitted
120 * segment are as specified by the parameters.
121 */
tcp_respond(struct tcpcb * tp,struct tcpiphdr * ti,struct mbuf * m,tcp_seq ack,tcp_seq seq,int flags,unsigned short af)122 void tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m,
123 tcp_seq ack, tcp_seq seq, int flags, unsigned short af)
124 {
125 register int tlen;
126 int win = 0;
127
128 DEBUG_CALL("tcp_respond");
129 DEBUG_ARG("tp = %p", tp);
130 DEBUG_ARG("ti = %p", ti);
131 DEBUG_ARG("m = %p", m);
132 DEBUG_ARG("ack = %u", ack);
133 DEBUG_ARG("seq = %u", seq);
134 DEBUG_ARG("flags = %x", flags);
135
136 if (tp)
137 win = sbspace(&tp->t_socket->so_rcv);
138 if (m == NULL) {
139 if (!tp || (m = m_get(tp->t_socket->slirp)) == NULL)
140 return;
141 tlen = 0;
142 m->m_data += IF_MAXLINKHDR;
143 *mtod(m, struct tcpiphdr *) = *ti;
144 ti = mtod(m, struct tcpiphdr *);
145 switch (af) {
146 case AF_INET:
147 ti->ti.ti_i4.ih_x1 = 0;
148 break;
149 case AF_INET6:
150 ti->ti.ti_i6.ih_x1 = 0;
151 break;
152 default:
153 g_assert_not_reached();
154 }
155 flags = TH_ACK;
156 } else {
157 /*
158 * ti points into m so the next line is just making
159 * the mbuf point to ti
160 */
161 m->m_data = (char *)ti;
162
163 m->m_len = sizeof(struct tcpiphdr);
164 tlen = 0;
165 #define xchg(a, b, type) \
166 { \
167 type t; \
168 t = a; \
169 a = b; \
170 b = t; \
171 }
172 switch (af) {
173 case AF_INET:
174 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, uint32_t);
175 xchg(ti->ti_dport, ti->ti_sport, uint16_t);
176 break;
177 case AF_INET6:
178 xchg(ti->ti_dst6, ti->ti_src6, struct in6_addr);
179 xchg(ti->ti_dport, ti->ti_sport, uint16_t);
180 break;
181 default:
182 g_assert_not_reached();
183 }
184 #undef xchg
185 }
186 ti->ti_len = htons((uint16_t)(sizeof(struct tcphdr) + tlen));
187 tlen += sizeof(struct tcpiphdr);
188 m->m_len = tlen;
189
190 ti->ti_mbuf = NULL;
191 ti->ti_x0 = 0;
192 ti->ti_seq = htonl(seq);
193 ti->ti_ack = htonl(ack);
194 ti->ti_x2 = 0;
195 ti->ti_off = sizeof(struct tcphdr) >> 2;
196 ti->ti_flags = flags;
197 if (tp)
198 ti->ti_win = htons((uint16_t)(win >> tp->rcv_scale));
199 else
200 ti->ti_win = htons((uint16_t)win);
201 ti->ti_urp = 0;
202 ti->ti_sum = 0;
203 ti->ti_sum = cksum(m, tlen);
204
205 struct tcpiphdr tcpiph_save = *(mtod(m, struct tcpiphdr *));
206 struct ip *ip;
207 struct ip6 *ip6;
208
209 switch (af) {
210 case AF_INET:
211 m->m_data +=
212 sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - sizeof(struct ip);
213 m->m_len -=
214 sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - sizeof(struct ip);
215 ip = mtod(m, struct ip *);
216 ip->ip_len = m->m_len;
217 ip->ip_dst = tcpiph_save.ti_dst;
218 ip->ip_src = tcpiph_save.ti_src;
219 ip->ip_p = tcpiph_save.ti_pr;
220
221 if (flags & TH_RST) {
222 ip->ip_ttl = MAXTTL;
223 } else {
224 ip->ip_ttl = IPDEFTTL;
225 }
226
227 ip_output(NULL, m);
228 break;
229
230 case AF_INET6:
231 m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr) -
232 sizeof(struct ip6);
233 m->m_len -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr) -
234 sizeof(struct ip6);
235 ip6 = mtod(m, struct ip6 *);
236 ip6->ip_pl = tcpiph_save.ti_len;
237 ip6->ip_dst = tcpiph_save.ti_dst6;
238 ip6->ip_src = tcpiph_save.ti_src6;
239 ip6->ip_nh = tcpiph_save.ti_nh6;
240
241 ip6_output(NULL, m, 0);
242 break;
243
244 default:
245 g_assert_not_reached();
246 }
247 }
248
249 /*
250 * Create a new TCP control block, making an
251 * empty reassembly queue and hooking it to the argument
252 * protocol control block.
253 */
tcp_newtcpcb(struct socket * so)254 struct tcpcb *tcp_newtcpcb(struct socket *so)
255 {
256 register struct tcpcb *tp;
257
258 tp = g_new0(struct tcpcb, 1);
259 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp;
260 /*
261 * 40: length of IPv4 header (20) + TCP header (20)
262 * 60: length of IPv6 header (40) + TCP header (20)
263 */
264 tp->t_maxseg =
265 MIN(so->slirp->if_mtu - ((so->so_ffamily == AF_INET) ? 40 : 60),
266 TCP_MAXSEG_MAX);
267
268 tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE | TF_REQ_TSTMP) : 0;
269 tp->t_socket = so;
270
271 /*
272 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
273 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives
274 * reasonable initial retransmit time.
275 */
276 tp->t_srtt = TCPTV_SRTTBASE;
277 tp->t_rttvar = TCPTV_SRTTDFLT << 2;
278 tp->t_rttmin = TCPTV_MIN;
279
280 TCPT_RANGESET(tp->t_rxtcur,
281 ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
282 TCPTV_MIN, TCPTV_REXMTMAX);
283
284 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
285 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
286 tp->t_state = TCPS_CLOSED;
287
288 so->so_tcpcb = tp;
289
290 return (tp);
291 }
292
293 /*
294 * Drop a TCP connection, reporting
295 * the specified error. If connection is synchronized,
296 * then send a RST to peer.
297 */
tcp_drop(struct tcpcb * tp,int err)298 struct tcpcb *tcp_drop(struct tcpcb *tp, int err)
299 {
300 DEBUG_CALL("tcp_drop");
301 DEBUG_ARG("tp = %p", tp);
302 DEBUG_ARG("errno = %d", errno);
303
304 if (TCPS_HAVERCVDSYN(tp->t_state)) {
305 tp->t_state = TCPS_CLOSED;
306 tcp_output(tp);
307 }
308 return (tcp_close(tp));
309 }
310
311 /*
312 * Close a TCP control block:
313 * discard all space held by the tcp
314 * discard internet protocol block
315 * wake up any sleepers
316 */
tcp_close(struct tcpcb * tp)317 struct tcpcb *tcp_close(struct tcpcb *tp)
318 {
319 register struct tcpiphdr *t;
320 struct socket *so = tp->t_socket;
321 Slirp *slirp = so->slirp;
322 register struct mbuf *m;
323
324 DEBUG_CALL("tcp_close");
325 DEBUG_ARG("tp = %p", tp);
326
327 /* free the reassembly queue, if any */
328 t = tcpfrag_list_first(tp);
329 while (!tcpfrag_list_end(t, tp)) {
330 t = tcpiphdr_next(t);
331 m = tcpiphdr_prev(t)->ti_mbuf;
332 remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
333 m_free(m);
334 }
335 g_free(tp);
336 so->so_tcpcb = NULL;
337 /* clobber input socket cache if we're closing the cached connection */
338 if (so == slirp->tcp_last_so)
339 slirp->tcp_last_so = &slirp->tcb;
340 so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
341 closesocket(so->s);
342 sbfree(&so->so_rcv);
343 sbfree(&so->so_snd);
344 sofree(so);
345 return ((struct tcpcb *)0);
346 }
347
348 /*
349 * TCP protocol interface to socket abstraction.
350 */
351
352 /*
353 * User issued close, and wish to trail through shutdown states:
354 * if never received SYN, just forget it. If got a SYN from peer,
355 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
356 * If already got a FIN from peer, then almost done; go to LAST_ACK
357 * state. In all other cases, have already sent FIN to peer (e.g.
358 * after PRU_SHUTDOWN), and just have to play tedious game waiting
359 * for peer to send FIN or not respond to keep-alives, etc.
360 * We can let the user exit from the close as soon as the FIN is acked.
361 */
tcp_sockclosed(struct tcpcb * tp)362 void tcp_sockclosed(struct tcpcb *tp)
363 {
364 DEBUG_CALL("tcp_sockclosed");
365 DEBUG_ARG("tp = %p", tp);
366
367 if (!tp) {
368 return;
369 }
370
371 switch (tp->t_state) {
372 case TCPS_CLOSED:
373 case TCPS_LISTEN:
374 case TCPS_SYN_SENT:
375 tp->t_state = TCPS_CLOSED;
376 tcp_close(tp);
377 return;
378
379 case TCPS_SYN_RECEIVED:
380 case TCPS_ESTABLISHED:
381 tp->t_state = TCPS_FIN_WAIT_1;
382 break;
383
384 case TCPS_CLOSE_WAIT:
385 tp->t_state = TCPS_LAST_ACK;
386 break;
387 }
388 tcp_output(tp);
389 }
390
391 /*
392 * Connect to a host on the Internet
393 * Called by tcp_input
394 * Only do a connect, the tcp fields will be set in tcp_input
395 * return 0 if there's a result of the connect,
396 * else return -1 means we're still connecting
397 * The return value is almost always -1 since the socket is
398 * nonblocking. Connect returns after the SYN is sent, and does
399 * not wait for ACK+SYN.
400 */
tcp_fconnect(struct socket * so,unsigned short af)401 int tcp_fconnect(struct socket *so, unsigned short af)
402 {
403 int ret = 0;
404
405 DEBUG_CALL("tcp_fconnect");
406 DEBUG_ARG("so = %p", so);
407
408 ret = so->s = slirp_socket(af, SOCK_STREAM, 0);
409 if (ret >= 0) {
410 ret = slirp_bind_outbound(so, af);
411 if (ret < 0) {
412 // bind failed - close socket
413 closesocket(so->s);
414 so->s = -1;
415 return (ret);
416 }
417 }
418
419 if (ret >= 0) {
420 int opt, s = so->s;
421 struct sockaddr_storage addr;
422
423 slirp_set_nonblock(s);
424 so->slirp->cb->register_poll_fd(s, so->slirp->opaque);
425 slirp_socket_set_fast_reuse(s);
426 opt = 1;
427 setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt));
428 opt = 1;
429 setsockopt(s, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
430
431 addr = so->fhost.ss;
432 DEBUG_CALL(" connect()ing");
433 if (sotranslate_out(so, &addr) < 0) {
434 return -1;
435 }
436
437 /* We don't care what port we get */
438 ret = connect(s, (struct sockaddr *)&addr, sockaddr_size(&addr));
439
440 /*
441 * If it's not in progress, it failed, so we just return 0,
442 * without clearing SS_NOFDREF
443 */
444 soisfconnecting(so);
445 }
446
447 return (ret);
448 }
449
450 /*
451 * Accept the socket and connect to the local-host
452 *
453 * We have a problem. The correct thing to do would be
454 * to first connect to the local-host, and only if the
455 * connection is accepted, then do an accept() here.
456 * But, a) we need to know who's trying to connect
457 * to the socket to be able to SYN the local-host, and
458 * b) we are already connected to the foreign host by
459 * the time it gets to accept(), so... We simply accept
460 * here and SYN the local-host.
461 */
tcp_connect(struct socket * inso)462 void tcp_connect(struct socket *inso)
463 {
464 Slirp *slirp = inso->slirp;
465 struct socket *so;
466 struct sockaddr_storage addr;
467 socklen_t addrlen = sizeof(struct sockaddr_storage);
468 struct tcpcb *tp;
469 int s, opt, ret;
470 /* AF_INET6 addresses are bigger than AF_INET, so this is big enough. */
471 char addrstr[INET6_ADDRSTRLEN];
472 char portstr[6];
473
474 DEBUG_CALL("tcp_connect");
475 DEBUG_ARG("inso = %p", inso);
476 ret = getnameinfo((const struct sockaddr *) &inso->lhost.ss, sizeof(inso->lhost.ss), addrstr, sizeof(addrstr), portstr, sizeof(portstr), NI_NUMERICHOST|NI_NUMERICSERV);
477 g_assert(ret == 0);
478 DEBUG_ARG("ip = [%s]:%s", addrstr, portstr);
479 DEBUG_ARG("so_state = 0x%x", inso->so_state);
480
481 /* Perform lazy guest IP address resolution if needed. */
482 if (inso->so_state & SS_HOSTFWD) {
483 /*
484 * We can only reject the connection request by accepting it and
485 * then immediately closing it. Note that SS_FACCEPTONCE sockets can't
486 * get here.
487 */
488 if (soassign_guest_addr_if_needed(inso) < 0) {
489 /*
490 * Guest address isn't available yet. We could either try to defer
491 * completing this connection request until the guest address is
492 * available, or punt. It's easier to punt. Otherwise we need to
493 * complicate the mechanism by which we're called to defer calling
494 * us again until the guest address is available.
495 */
496 DEBUG_MISC(" guest address not available yet");
497 s = accept(inso->s, (struct sockaddr *)&addr, &addrlen);
498 if (s >= 0) {
499 close(s);
500 }
501 return;
502 }
503 }
504
505 /*
506 * If it's an SS_ACCEPTONCE socket, no need to socreate()
507 * another socket, just use the accept() socket.
508 */
509 if (inso->so_state & SS_FACCEPTONCE) {
510 /* FACCEPTONCE already have a tcpcb */
511 so = inso;
512 } else {
513 so = socreate(slirp);
514 tcp_attach(so);
515 so->lhost = inso->lhost;
516 so->so_ffamily = inso->so_ffamily;
517 }
518
519 tcp_mss(sototcpcb(so), 0);
520
521 s = accept(inso->s, (struct sockaddr *)&addr, &addrlen);
522 if (s < 0) {
523 tcp_close(sototcpcb(so)); /* This will sofree() as well */
524 return;
525 }
526 slirp_set_nonblock(s);
527 so->slirp->cb->register_poll_fd(s, so->slirp->opaque);
528 slirp_socket_set_fast_reuse(s);
529 opt = 1;
530 setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int));
531 slirp_socket_set_nodelay(s);
532
533 so->fhost.ss = addr;
534 sotranslate_accept(so);
535
536 /* Close the accept() socket, set right state */
537 if (inso->so_state & SS_FACCEPTONCE) {
538 /* If we only accept once, close the accept() socket */
539 so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
540 closesocket(so->s);
541
542 /* Don't select it yet, even though we have an FD */
543 /* if it's not FACCEPTONCE, it's already NOFDREF */
544 so->so_state = SS_NOFDREF;
545 }
546 so->s = s;
547 so->so_state |= SS_INCOMING;
548
549 so->so_iptos = tcp_tos(so);
550 tp = sototcpcb(so);
551
552 tcp_template(tp);
553
554 tp->t_state = TCPS_SYN_SENT;
555 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
556 tp->iss = slirp->tcp_iss;
557 slirp->tcp_iss += TCP_ISSINCR / 2;
558 tcp_sendseqinit(tp);
559 tcp_output(tp);
560 }
561
562 /*
563 * Attach a TCPCB to a socket.
564 */
tcp_attach(struct socket * so)565 void tcp_attach(struct socket *so)
566 {
567 so->so_tcpcb = tcp_newtcpcb(so);
568 insque(so, &so->slirp->tcb);
569 }
570
571 /*
572 * Set the socket's type of service field
573 */
574 static const struct tos_t tcptos[] = {
575 { 0, 20, IPTOS_THROUGHPUT, 0 }, /* ftp data */
576 { 21, 21, IPTOS_LOWDELAY, EMU_FTP }, /* ftp control */
577 { 0, 23, IPTOS_LOWDELAY, 0 }, /* telnet */
578 { 0, 80, IPTOS_THROUGHPUT, 0 }, /* WWW */
579 { 0, 513, IPTOS_LOWDELAY, EMU_RLOGIN | EMU_NOCONNECT }, /* rlogin */
580 { 0, 544, IPTOS_LOWDELAY, EMU_KSH }, /* kshell */
581 { 0, 543, IPTOS_LOWDELAY, 0 }, /* klogin */
582 { 0, 6667, IPTOS_THROUGHPUT, EMU_IRC }, /* IRC */
583 { 0, 6668, IPTOS_THROUGHPUT, EMU_IRC }, /* IRC undernet */
584 { 0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
585 { 0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
586 { 0, 0, 0, 0 }
587 };
588
589 /*
590 * Return TOS according to the above table
591 */
tcp_tos(struct socket * so)592 uint8_t tcp_tos(struct socket *so)
593 {
594 int i = 0;
595
596 while (tcptos[i].tos) {
597 if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
598 (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
599 if (so->slirp->enable_emu)
600 so->so_emu = tcptos[i].emu;
601 return tcptos[i].tos;
602 }
603 i++;
604 }
605 return 0;
606 }
607
608 /*
609 * Emulate programs that try and connect to us
610 * This includes ftp (the data connection is
611 * initiated by the server) and IRC (DCC CHAT and
612 * DCC SEND) for now
613 *
614 * NOTE: It's possible to crash SLiRP by sending it
615 * unstandard strings to emulate... if this is a problem,
616 * more checks are needed here
617 *
618 * XXX Assumes the whole command came in one packet
619 * XXX If there is more than one command in the packet, the others may
620 * be truncated.
621 * XXX If the command is too long, it may be truncated.
622 *
623 * XXX Some ftp clients will have their TOS set to
624 * LOWDELAY and so Nagel will kick in. Because of this,
625 * we'll get the first letter, followed by the rest, so
626 * we simply scan for ORT instead of PORT...
627 * DCC doesn't have this problem because there's other stuff
628 * in the packet before the DCC command.
629 *
630 * Return 1 if the mbuf m is still valid and should be
631 * sbappend()ed
632 *
633 * NOTE: if you return 0 you MUST m_free() the mbuf!
634 */
tcp_emu(struct socket * so,struct mbuf * m)635 int tcp_emu(struct socket *so, struct mbuf *m)
636 {
637 Slirp *slirp = so->slirp;
638 unsigned n1, n2, n3, n4, n5, n6;
639 char buff[257];
640 uint32_t laddr;
641 unsigned lport;
642 char *bptr;
643
644 DEBUG_CALL("tcp_emu");
645 DEBUG_ARG("so = %p", so);
646 DEBUG_ARG("m = %p", m);
647
648 switch (so->so_emu) {
649 int x, i;
650
651 /* TODO: IPv6 */
652 case EMU_IDENT:
653 /*
654 * Identification protocol as per rfc-1413
655 */
656
657 {
658 struct socket *tmpso;
659 struct sockaddr_in addr;
660 socklen_t addrlen = sizeof(struct sockaddr_in);
661 char *eol = g_strstr_len(m->m_data, m->m_len, "\r\n");
662
663 if (!eol) {
664 return 1;
665 }
666
667 *eol = '\0';
668 if (sscanf(m->m_data, "%u%*[ ,]%u", &n1, &n2) == 2) {
669 HTONS(n1);
670 HTONS(n2);
671 /* n2 is the one on our host */
672 for (tmpso = slirp->tcb.so_next; tmpso != &slirp->tcb;
673 tmpso = tmpso->so_next) {
674 if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
675 tmpso->so_lport == n2 &&
676 tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
677 tmpso->so_fport == n1) {
678 if (getsockname(tmpso->s, (struct sockaddr *)&addr,
679 &addrlen) == 0)
680 n2 = addr.sin_port;
681 break;
682 }
683 }
684 NTOHS(n1);
685 NTOHS(n2);
686 m_inc(m, g_snprintf(NULL, 0, "%d,%d\r\n", n1, n2) + 1);
687 m->m_len = slirp_fmt(m->m_data, M_ROOM(m), "%d,%d\r\n", n1, n2);
688 } else {
689 *eol = '\r';
690 }
691
692 return 1;
693 }
694
695 case EMU_FTP: /* ftp */
696 m_inc(m, m->m_len + 1);
697 *(m->m_data + m->m_len) = 0; /* NUL terminate for strstr */
698 if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
699 /*
700 * Need to emulate the PORT command
701 */
702 x = sscanf(bptr, "ORT %u,%u,%u,%u,%u,%u\r\n%256[^\177]", &n1, &n2,
703 &n3, &n4, &n5, &n6, buff);
704 if (x < 6)
705 return 1;
706
707 laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
708 lport = htons((n5 << 8) | (n6));
709
710 if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr, lport,
711 SS_FACCEPTONCE)) == NULL) {
712 return 1;
713 }
714 n6 = ntohs(so->so_fport);
715
716 n5 = (n6 >> 8) & 0xff;
717 n6 &= 0xff;
718
719 laddr = ntohl(so->so_faddr.s_addr);
720
721 n1 = ((laddr >> 24) & 0xff);
722 n2 = ((laddr >> 16) & 0xff);
723 n3 = ((laddr >> 8) & 0xff);
724 n4 = (laddr & 0xff);
725
726 m->m_len = bptr - m->m_data; /* Adjust length */
727 m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
728 "ORT %d,%d,%d,%d,%d,%d\r\n%s",
729 n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
730 return 1;
731 } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
732 /*
733 * Need to emulate the PASV response
734 */
735 x = sscanf(
736 bptr,
737 "27 Entering Passive Mode (%u,%u,%u,%u,%u,%u)\r\n%256[^\177]",
738 &n1, &n2, &n3, &n4, &n5, &n6, buff);
739 if (x < 6)
740 return 1;
741
742 laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
743 lport = htons((n5 << 8) | (n6));
744
745 if ((so = tcp_listen(slirp, INADDR_ANY, 0, laddr, lport,
746 SS_FACCEPTONCE)) == NULL) {
747 return 1;
748 }
749 n6 = ntohs(so->so_fport);
750
751 n5 = (n6 >> 8) & 0xff;
752 n6 &= 0xff;
753
754 laddr = ntohl(so->so_faddr.s_addr);
755
756 n1 = ((laddr >> 24) & 0xff);
757 n2 = ((laddr >> 16) & 0xff);
758 n3 = ((laddr >> 8) & 0xff);
759 n4 = (laddr & 0xff);
760
761 m->m_len = bptr - m->m_data; /* Adjust length */
762 m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
763 "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
764 n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
765 return 1;
766 }
767
768 return 1;
769
770 case EMU_KSH:
771 /*
772 * The kshell (Kerberos rsh) and shell services both pass
773 * a local port port number to carry signals to the server
774 * and stderr to the client. It is passed at the beginning
775 * of the connection as a NUL-terminated decimal ASCII string.
776 */
777 so->so_emu = 0;
778 for (lport = 0, i = 0; i < m->m_len - 1; ++i) {
779 if (m->m_data[i] < '0' || m->m_data[i] > '9')
780 return 1; /* invalid number */
781 lport *= 10;
782 lport += m->m_data[i] - '0';
783 }
784 if (m->m_data[m->m_len - 1] == '\0' && lport != 0 &&
785 (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
786 htons(lport), SS_FACCEPTONCE)) != NULL)
787 m->m_len = slirp_fmt0(m->m_data, M_ROOM(m),
788 "%d", ntohs(so->so_fport));
789 return 1;
790
791 case EMU_IRC:
792 /*
793 * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
794 */
795 m_inc(m, m->m_len + 1);
796 *(m->m_data + m->m_len) = 0; /* NULL terminate the string for strstr */
797 if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
798 return 1;
799
800 /* The %256s is for the broken mIRC */
801 if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
802 if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr),
803 htons(lport), SS_FACCEPTONCE)) == NULL) {
804 return 1;
805 }
806 m->m_len = bptr - m->m_data; /* Adjust length */
807 m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
808 "DCC CHAT chat %lu %u%c\n",
809 (unsigned long)ntohl(so->so_faddr.s_addr),
810 ntohs(so->so_fport), 1);
811 } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport,
812 &n1) == 4) {
813 if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr),
814 htons(lport), SS_FACCEPTONCE)) == NULL) {
815 return 1;
816 }
817 m->m_len = bptr - m->m_data; /* Adjust length */
818 m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
819 "DCC SEND %s %lu %u %u%c\n", buff,
820 (unsigned long)ntohl(so->so_faddr.s_addr),
821 ntohs(so->so_fport), n1, 1);
822 } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport,
823 &n1) == 4) {
824 if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr),
825 htons(lport), SS_FACCEPTONCE)) == NULL) {
826 return 1;
827 }
828 m->m_len = bptr - m->m_data; /* Adjust length */
829 m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
830 "DCC MOVE %s %lu %u %u%c\n", buff,
831 (unsigned long)ntohl(so->so_faddr.s_addr),
832 ntohs(so->so_fport), n1, 1);
833 }
834 return 1;
835
836 case EMU_REALAUDIO:
837 /*
838 * RealAudio emulation - JP. We must try to parse the incoming
839 * data and try to find the two characters that contain the
840 * port number. Then we redirect an udp port and replace the
841 * number with the real port we got.
842 *
843 * The 1.0 beta versions of the player are not supported
844 * any more.
845 *
846 * A typical packet for player version 1.0 (release version):
847 *
848 * 0000:50 4E 41 00 05
849 * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 ........g.l.c..P
850 * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
851 * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
852 * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
853 *
854 * Now the port number 0x1BD7 is found at offset 0x04 of the
855 * Now the port number 0x1BD7 is found at offset 0x04 of the
856 * second packet. This time we received five bytes first and
857 * then the rest. You never know how many bytes you get.
858 *
859 * A typical packet for player version 2.0 (beta):
860 *
861 * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA.............
862 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .gux.c..Win2.0.0
863 * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
864 * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
865 * 0040:65 2E 72 61 79 53 00 00 06 36 42 e.rayS...6B
866 *
867 * Port number 0x1BC1 is found at offset 0x0d.
868 *
869 * This is just a horrible switch statement. Variable ra tells
870 * us where we're going.
871 */
872
873 bptr = m->m_data;
874 while (bptr < m->m_data + m->m_len) {
875 uint16_t p;
876 static int ra = 0;
877 char ra_tbl[4];
878
879 ra_tbl[0] = 0x50;
880 ra_tbl[1] = 0x4e;
881 ra_tbl[2] = 0x41;
882 ra_tbl[3] = 0;
883
884 switch (ra) {
885 case 0:
886 case 2:
887 case 3:
888 if (*bptr++ != ra_tbl[ra]) {
889 ra = 0;
890 continue;
891 }
892 break;
893
894 case 1:
895 /*
896 * We may get 0x50 several times, ignore them
897 */
898 if (*bptr == 0x50) {
899 ra = 1;
900 bptr++;
901 continue;
902 } else if (*bptr++ != ra_tbl[ra]) {
903 ra = 0;
904 continue;
905 }
906 break;
907
908 case 4:
909 /*
910 * skip version number
911 */
912 bptr++;
913 break;
914
915 case 5:
916 if (bptr == m->m_data + m->m_len - 1)
917 return 1; /* We need two bytes */
918
919 /*
920 * The difference between versions 1.0 and
921 * 2.0 is here. For future versions of
922 * the player this may need to be modified.
923 */
924 if (*(bptr + 1) == 0x02)
925 bptr += 8;
926 else
927 bptr += 4;
928 break;
929
930 case 6:
931 /* This is the field containing the port
932 * number that RA-player is listening to.
933 */
934
935 if (bptr == m->m_data + m->m_len - 1)
936 return 1; /* We need two bytes */
937
938 lport = (((uint8_t *)bptr)[0] << 8) + ((uint8_t *)bptr)[1];
939 if (lport < 6970)
940 lport += 256; /* don't know why */
941 if (lport < 6970 || lport > 7170)
942 return 1; /* failed */
943
944 /* try to get udp port between 6970 - 7170 */
945 for (p = 6970; p < 7071; p++) {
946 if (udp_listen(slirp, INADDR_ANY, htons(p),
947 so->so_laddr.s_addr, htons(lport),
948 SS_FACCEPTONCE)) {
949 break;
950 }
951 }
952 if (p == 7071)
953 p = 0;
954 *(uint8_t *)bptr++ = (p >> 8) & 0xff;
955 *(uint8_t *)bptr = p & 0xff;
956 ra = 0;
957 return 1; /* port redirected, we're done */
958 break;
959
960 default:
961 ra = 0;
962 }
963 ra++;
964 }
965 return 1;
966
967 default:
968 /* Ooops, not emulated, won't call tcp_emu again */
969 so->so_emu = 0;
970 return 1;
971 }
972 }
973
974 /*
975 * Do misc. config of SLiRP while its running.
976 * Return 0 if this connections is to be closed, 1 otherwise,
977 * return 2 if this is a command-line connection
978 */
tcp_ctl(struct socket * so)979 int tcp_ctl(struct socket *so)
980 {
981 Slirp *slirp = so->slirp;
982 struct sbuf *sb = &so->so_snd;
983 struct gfwd_list *ex_ptr;
984
985 DEBUG_CALL("tcp_ctl");
986 DEBUG_ARG("so = %p", so);
987
988 /* TODO: IPv6 */
989 if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr) {
990 /* Check if it's pty_exec */
991 for (ex_ptr = slirp->guestfwd_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
992 if (ex_ptr->ex_fport == so->so_fport &&
993 so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
994 if (ex_ptr->write_cb) {
995 so->s = -1;
996 so->guestfwd = ex_ptr;
997 return 1;
998 }
999 DEBUG_MISC(" executing %s", ex_ptr->ex_exec);
1000 if (ex_ptr->ex_unix)
1001 return open_unix(so, ex_ptr->ex_unix);
1002 else
1003 return fork_exec(so, ex_ptr->ex_exec);
1004 }
1005 }
1006 }
1007 sb->sb_cc = slirp_fmt(sb->sb_wptr, sb->sb_datalen - (sb->sb_wptr - sb->sb_data),
1008 "Error: No application configured.\r\n");
1009 sb->sb_wptr += sb->sb_cc;
1010 return 0;
1011 }
1012