2 * Platform-independent bits of X11 forwarding.
14 #define GET_16BIT(endian, cp) \
15 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
17 #define PUT_16BIT(endian, cp, val) \
18 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
20 const char *const x11_authnames[] = {
21 "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
26 unsigned char clientid[6];
29 struct X11Connection {
30 const struct plug_function_table *fn;
31 /* the above variable absolutely *must* be the first in this structure */
32 unsigned char firstpkt[12]; /* first X data packet */
34 struct X11Display *disp;
36 unsigned char *auth_data;
37 int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
39 int throttled, throttle_override;
40 int no_data_sent_to_x_client;
43 struct ssh_channel *c; /* channel structure held by ssh.c */
47 static int xdmseen_cmp(void *a, void *b)
49 struct XDMSeen *sa = a, *sb = b;
50 return sa->time > sb->time ? 1 :
51 sa->time < sb->time ? -1 :
52 memcmp(sa->clientid, sb->clientid, sizeof(sa->clientid));
55 /* Do-nothing "plug" implementation, used by x11_setup_display() when it
56 * creates a trial connection (and then immediately closes it).
57 * XXX: bit out of place here, could in principle live in a platform-
58 * independent network.c or something */
59 static void dummy_plug_log(Plug p, int type, SockAddr addr, int port,
60 const char *error_msg, int error_code) { }
61 static int dummy_plug_closing
62 (Plug p, const char *error_msg, int error_code, int calling_back)
64 static int dummy_plug_receive(Plug p, int urgent, char *data, int len)
66 static void dummy_plug_sent(Plug p, int bufsize) { }
67 static int dummy_plug_accepting(Plug p, accept_fn_t constructor, accept_ctx_t ctx) { return 1; }
68 static const struct plug_function_table dummy_plug = {
69 dummy_plug_log, dummy_plug_closing, dummy_plug_receive,
70 dummy_plug_sent, dummy_plug_accepting
73 struct X11FakeAuth *x11_invent_fake_auth(tree234 *authtree, int authtype)
75 struct X11FakeAuth *auth = snew(struct X11FakeAuth);
79 * This function has the job of inventing a set of X11 fake auth
80 * data, and adding it to 'authtree'. We must preserve the
81 * property that for any given actual authorisation attempt, _at
82 * most one_ thing in the tree can possibly match it.
84 * For MIT-MAGIC-COOKIE-1, that's not too difficult: the match
85 * criterion is simply that the entire cookie is correct, so we
86 * just have to make sure we don't make up two cookies the same.
87 * (Vanishingly unlikely, but we check anyway to be sure, and go
88 * round again inventing a new cookie if add234 tells us the one
89 * we thought of is already in use.)
91 * For XDM-AUTHORIZATION-1, it's a little more fiddly. The setup
92 * with XA1 is that half the cookie is used as a DES key with
93 * which to CBC-encrypt an assortment of stuff. Happily, the stuff
94 * encrypted _begins_ with the other half of the cookie, and the
95 * IV is always zero, which means that any valid XA1 authorisation
96 * attempt for a given cookie must begin with the same cipher
97 * block, consisting of the DES ECB encryption of the first half
98 * of the cookie using the second half as a key. So we compute
99 * that cipher block here and now, and use it as the sorting key
100 * for distinguishing XA1 entries in the tree.
103 if (authtype == X11_MIT) {
104 auth->proto = X11_MIT;
106 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
108 auth->data = snewn(auth->datalen, unsigned char);
109 auth->xa1_firstblock = NULL;
112 for (i = 0; i < auth->datalen; i++)
113 auth->data[i] = random_byte();
114 if (add234(authtree, auth) == auth)
118 auth->xdmseen = NULL;
120 assert(authtype == X11_XDM);
121 auth->proto = X11_XDM;
123 /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
125 auth->data = snewn(auth->datalen, unsigned char);
126 auth->xa1_firstblock = snewn(8, unsigned char);
127 memset(auth->xa1_firstblock, 0, 8);
130 for (i = 0; i < auth->datalen; i++)
131 auth->data[i] = (i == 8 ? 0 : random_byte());
132 memcpy(auth->xa1_firstblock, auth->data, 8);
133 des_encrypt_xdmauth(auth->data + 9, auth->xa1_firstblock, 8);
134 if (add234(authtree, auth) == auth)
138 auth->xdmseen = newtree234(xdmseen_cmp);
140 auth->protoname = dupstr(x11_authnames[auth->proto]);
141 auth->datastring = snewn(auth->datalen * 2 + 1, char);
142 for (i = 0; i < auth->datalen; i++)
143 sprintf(auth->datastring + i*2, "%02x",
147 auth->share_cs = auth->share_chan = NULL;
152 void x11_free_fake_auth(struct X11FakeAuth *auth)
155 smemclr(auth->data, auth->datalen);
157 sfree(auth->protoname);
158 sfree(auth->datastring);
159 sfree(auth->xa1_firstblock);
160 if (auth->xdmseen != NULL) {
161 struct XDMSeen *seen;
162 while ((seen = delpos234(auth->xdmseen, 0)) != NULL)
164 freetree234(auth->xdmseen);
169 int x11_authcmp(void *av, void *bv)
171 struct X11FakeAuth *a = (struct X11FakeAuth *)av;
172 struct X11FakeAuth *b = (struct X11FakeAuth *)bv;
174 if (a->proto < b->proto)
176 else if (a->proto > b->proto)
179 if (a->proto == X11_MIT) {
180 if (a->datalen < b->datalen)
182 else if (a->datalen > b->datalen)
185 return memcmp(a->data, b->data, a->datalen);
187 assert(a->proto == X11_XDM);
189 return memcmp(a->xa1_firstblock, b->xa1_firstblock, 8);
193 struct X11Display *x11_setup_display(const char *display, Conf *conf)
195 struct X11Display *disp = snew(struct X11Display);
198 if (!display || !*display) {
199 localcopy = platform_get_x_display();
200 if (!localcopy || !*localcopy) {
202 localcopy = dupstr(":0"); /* plausible default for any platform */
205 localcopy = dupstr(display);
208 * Parse the display name.
210 * We expect this to have one of the following forms:
212 * - the standard X format which looks like
213 * [ [ protocol '/' ] host ] ':' displaynumber [ '.' screennumber ]
214 * (X11 also permits a double colon to indicate DECnet, but
215 * that's not our problem, thankfully!)
217 * - only seen in the wild on MacOS (so far): a pathname to a
218 * Unix-domain socket, which will typically and confusingly
219 * end in ":0", and which I'm currently distinguishing from
220 * the standard scheme by noting that it starts with '/'.
222 if (localcopy[0] == '/') {
223 disp->unixsocketpath = localcopy;
224 disp->unixdomain = TRUE;
225 disp->hostname = NULL;
226 disp->displaynum = -1;
230 char *colon, *dot, *slash;
231 char *protocol, *hostname;
233 colon = host_strrchr(localcopy, ':');
237 return NULL; /* FIXME: report a specific error? */
241 dot = strchr(colon, '.');
245 disp->displaynum = atoi(colon);
247 disp->screennum = atoi(dot);
252 hostname = localcopy;
253 if (colon > localcopy) {
254 slash = strchr(localcopy, '/');
257 protocol = localcopy;
262 disp->hostname = *hostname ? dupstr(hostname) : NULL;
265 disp->unixdomain = (!strcmp(protocol, "local") ||
266 !strcmp(protocol, "unix"));
267 else if (!*hostname || !strcmp(hostname, "unix"))
268 disp->unixdomain = platform_uses_x11_unix_by_default;
270 disp->unixdomain = FALSE;
272 if (!disp->hostname && !disp->unixdomain)
273 disp->hostname = dupstr("localhost");
275 disp->unixsocketpath = NULL;
282 * Look up the display hostname, if we need to.
284 if (!disp->unixdomain) {
287 disp->port = 6000 + disp->displaynum;
288 disp->addr = name_lookup(disp->hostname, disp->port,
289 &disp->realhost, conf, ADDRTYPE_UNSPEC);
291 if ((err = sk_addr_error(disp->addr)) != NULL) {
292 sk_addr_free(disp->addr);
293 sfree(disp->hostname);
294 sfree(disp->unixsocketpath);
296 return NULL; /* FIXME: report an error */
301 * Try upgrading an IP-style localhost display to a Unix-socket
302 * display (as the standard X connection libraries do).
304 if (!disp->unixdomain && sk_address_is_local(disp->addr)) {
305 SockAddr ux = platform_get_x11_unix_address(NULL, disp->displaynum);
306 const char *err = sk_addr_error(ux);
308 /* Create trial connection to see if there is a useful Unix-domain
310 const struct plug_function_table *dummy = &dummy_plug;
311 Socket s = sk_new(sk_addr_dup(ux), 0, 0, 0, 0, 0, (Plug)&dummy);
312 err = sk_socket_error(s);
318 sk_addr_free(disp->addr);
319 disp->unixdomain = TRUE;
321 /* Fill in the rest in a moment */
325 if (disp->unixdomain) {
327 disp->addr = platform_get_x11_unix_address(disp->unixsocketpath,
329 if (disp->unixsocketpath)
330 disp->realhost = dupstr(disp->unixsocketpath);
332 disp->realhost = dupprintf("unix:%d", disp->displaynum);
337 * Fetch the local authorisation details.
339 disp->localauthproto = X11_NO_AUTH;
340 disp->localauthdata = NULL;
341 disp->localauthdatalen = 0;
342 platform_get_x11_auth(disp, conf);
347 void x11_free_display(struct X11Display *disp)
349 sfree(disp->hostname);
350 sfree(disp->unixsocketpath);
351 if (disp->localauthdata)
352 smemclr(disp->localauthdata, disp->localauthdatalen);
353 sfree(disp->localauthdata);
354 sk_addr_free(disp->addr);
358 #define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */
360 static char *x11_verify(unsigned long peer_ip, int peer_port,
361 tree234 *authtree, char *proto,
362 unsigned char *data, int dlen,
363 struct X11FakeAuth **auth_ret)
365 struct X11FakeAuth match_dummy; /* for passing to find234 */
366 struct X11FakeAuth *auth;
369 * First, do a lookup in our tree to find the only authorisation
370 * record that _might_ match.
372 if (!strcmp(proto, x11_authnames[X11_MIT])) {
374 * Just look up the whole cookie that was presented to us,
375 * which x11_authcmp will compare against the cookies we
376 * currently believe in.
378 match_dummy.proto = X11_MIT;
379 match_dummy.datalen = dlen;
380 match_dummy.data = data;
381 } else if (!strcmp(proto, x11_authnames[X11_XDM])) {
383 * Look up the first cipher block, against the stored first
384 * cipher blocks for the XDM-AUTHORIZATION-1 cookies we
385 * currently know. (See comment in x11_invent_fake_auth.)
387 match_dummy.proto = X11_XDM;
388 match_dummy.xa1_firstblock = data;
390 return "Unsupported authorisation protocol";
393 if ((auth = find234(authtree, &match_dummy, 0)) == NULL)
394 return "Authorisation not recognised";
397 * If we're using MIT-MAGIC-COOKIE-1, that was all we needed. If
398 * we're doing XDM-AUTHORIZATION-1, though, we have to check the
399 * rest of the auth data.
401 if (auth->proto == X11_XDM) {
405 struct XDMSeen *seen, *ret;
408 return "XDM-AUTHORIZATION-1 data was wrong length";
410 return "cannot do XDM-AUTHORIZATION-1 without remote address data";
411 des_decrypt_xdmauth(auth->data+9, data, 24);
412 if (memcmp(auth->data, data, 8) != 0)
413 return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
414 if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
415 return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
416 if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
417 return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
418 t = GET_32BIT_MSB_FIRST(data+14);
419 for (i = 18; i < 24; i++)
420 if (data[i] != 0) /* zero padding wrong */
421 return "XDM-AUTHORIZATION-1 data failed check";
423 if (abs(t - tim) > XDM_MAXSKEW)
424 return "XDM-AUTHORIZATION-1 time stamp was too far out";
425 seen = snew(struct XDMSeen);
427 memcpy(seen->clientid, data+8, 6);
428 assert(auth->xdmseen != NULL);
429 ret = add234(auth->xdmseen, seen);
432 return "XDM-AUTHORIZATION-1 data replayed";
434 /* While we're here, purge entries too old to be replayed. */
436 seen = index234(auth->xdmseen, 0);
437 assert(seen != NULL);
438 if (t - seen->time <= XDM_MAXSKEW)
440 sfree(delpos234(auth->xdmseen, 0));
443 /* implement other protocols here if ever required */
449 void x11_get_auth_from_authfile(struct X11Display *disp,
450 const char *authfilename)
453 char *buf, *ptr, *str[4];
455 int family, protocol;
456 int ideal_match = FALSE;
460 * Normally we should look for precisely the details specified in
461 * `disp'. However, there's an oddity when the display is local:
462 * displays like "localhost:0" usually have their details stored
463 * in a Unix-domain-socket record (even if there isn't actually a
464 * real Unix-domain socket available, as with OpenSSH's proxy X11
467 * This is apparently a fudge to get round the meaninglessness of
468 * "localhost" in a shared-home-directory context -- xauth entries
469 * for Unix-domain sockets already disambiguate this by storing
470 * the *local* hostname in the conveniently-blank hostname field,
471 * but IP "localhost" records couldn't do this. So, typically, an
472 * IP "localhost" entry in the auth database isn't present and if
473 * it were it would be ignored.
475 * However, we don't entirely trust that (say) Windows X servers
476 * won't rely on a straight "localhost" entry, bad idea though
477 * that is; so if we can't find a Unix-domain-socket entry we'll
478 * fall back to an IP-based entry if we can find one.
480 int localhost = !disp->unixdomain && sk_address_is_local(disp->addr);
482 authfp = fopen(authfilename, "rb");
486 ourhostname = get_hostname();
488 /* Records in .Xauthority contain four strings of up to 64K each */
489 buf = snewn(65537 * 4, char);
491 while (!ideal_match) {
492 int c, i, j, match = FALSE;
494 #define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0)
495 /* Expect a big-endian 2-byte number giving address family */
497 GET; family = (family << 8) | c;
498 /* Then expect four strings, each composed of a big-endian 2-byte
499 * length field followed by that many bytes of data */
501 for (i = 0; i < 4; i++) {
503 GET; len[i] = (len[i] << 8) | c;
505 for (j = 0; j < len[i]; j++) {
513 * Now we have a full X authority record in memory. See
514 * whether it matches the display we're trying to
517 * The details we've just read should be interpreted as
520 * - 'family' is the network address family used to
521 * connect to the display. 0 means IPv4; 6 means IPv6;
522 * 256 means Unix-domain sockets.
524 * - str[0] is the network address itself. For IPv4 and
525 * IPv6, this is a string of binary data of the
526 * appropriate length (respectively 4 and 16 bytes)
527 * representing the address in big-endian format, e.g.
528 * 7F 00 00 01 means IPv4 localhost. For Unix-domain
529 * sockets, this is the host name of the machine on
530 * which the Unix-domain display resides (so that an
531 * .Xauthority file on a shared file system can contain
532 * authority entries for Unix-domain displays on
533 * several machines without them clashing).
535 * - str[1] is the display number. I've no idea why
536 * .Xauthority stores this as a string when it has a
537 * perfectly good integer format, but there we go.
539 * - str[2] is the authorisation method, encoded as its
540 * canonical string name (i.e. "MIT-MAGIC-COOKIE-1",
541 * "XDM-AUTHORIZATION-1" or something we don't
544 * - str[3] is the actual authorisation data, stored in
548 if (disp->displaynum < 0 || disp->displaynum != atoi(str[1]))
549 continue; /* not the one */
551 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
552 if (!strcmp(str[2], x11_authnames[protocol]))
554 if (protocol == lenof(x11_authnames))
555 continue; /* don't recognise this protocol, look for another */
559 if (!disp->unixdomain &&
560 sk_addrtype(disp->addr) == ADDRTYPE_IPV4) {
562 sk_addrcopy(disp->addr, buf);
563 if (len[0] == 4 && !memcmp(str[0], buf, 4)) {
565 /* If this is a "localhost" entry, note it down
566 * but carry on looking for a Unix-domain entry. */
567 ideal_match = !localhost;
572 if (!disp->unixdomain &&
573 sk_addrtype(disp->addr) == ADDRTYPE_IPV6) {
575 sk_addrcopy(disp->addr, buf);
576 if (len[0] == 16 && !memcmp(str[0], buf, 16)) {
578 ideal_match = !localhost;
582 case 256: /* Unix-domain / localhost */
583 if ((disp->unixdomain || localhost)
584 && ourhostname && !strcmp(ourhostname, str[0]))
585 /* A matching Unix-domain socket is always the best
587 match = ideal_match = TRUE;
592 /* Current best guess -- may be overridden if !ideal_match */
593 disp->localauthproto = protocol;
594 sfree(disp->localauthdata); /* free previous guess, if any */
595 disp->localauthdata = snewn(len[3], unsigned char);
596 memcpy(disp->localauthdata, str[3], len[3]);
597 disp->localauthdatalen = len[3];
603 smemclr(buf, 65537 * 4);
608 static void x11_log(Plug p, int type, SockAddr addr, int port,
609 const char *error_msg, int error_code)
611 /* We have no interface to the logging module here, so we drop these. */
614 static void x11_send_init_error(struct X11Connection *conn,
615 const char *err_message);
617 static int x11_closing(Plug plug, const char *error_msg, int error_code,
620 struct X11Connection *xconn = (struct X11Connection *) plug;
624 * Socket error. If we're still at the connection setup stage,
625 * construct an X11 error packet passing on the problem.
627 if (xconn->no_data_sent_to_x_client) {
628 char *err_message = dupprintf("unable to connect to forwarded "
629 "X server: %s", error_msg);
630 x11_send_init_error(xconn, err_message);
635 * Whether we did that or not, now we slam the connection
638 sshfwd_unclean_close(xconn->c, error_msg);
641 * Ordinary EOF received on socket. Send an EOF on the SSH
645 sshfwd_write_eof(xconn->c);
651 static int x11_receive(Plug plug, int urgent, char *data, int len)
653 struct X11Connection *xconn = (struct X11Connection *) plug;
655 if (sshfwd_write(xconn->c, data, len) > 0) {
656 xconn->throttled = 1;
657 xconn->no_data_sent_to_x_client = FALSE;
658 sk_set_frozen(xconn->s, 1);
664 static void x11_sent(Plug plug, int bufsize)
666 struct X11Connection *xconn = (struct X11Connection *) plug;
668 sshfwd_unthrottle(xconn->c, bufsize);
672 * When setting up X forwarding, we should send the screen number
673 * from the specified local display. This function extracts it from
674 * the display string.
676 int x11_get_screen_number(char *display)
680 n = host_strcspn(display, ":");
683 n = strcspn(display, ".");
686 return atoi(display + n + 1);
690 * Called to set up the X11Connection structure, though this does not
691 * yet connect to an actual server.
693 struct X11Connection *x11_init(tree234 *authtree, void *c,
694 const char *peeraddr, int peerport)
696 static const struct plug_function_table fn_table = {
704 struct X11Connection *xconn;
709 xconn = snew(struct X11Connection);
710 xconn->fn = &fn_table;
711 xconn->auth_protocol = NULL;
712 xconn->authtree = authtree;
714 xconn->data_read = 0;
715 xconn->throttled = xconn->throttle_override = 0;
716 xconn->no_data_sent_to_x_client = TRUE;
720 * We don't actually open a local socket to the X server just yet,
721 * because we don't know which one it is. Instead, we'll wait
722 * until we see the incoming authentication data, which may tell
723 * us what display to connect to, or whether we have to divert
724 * this X forwarding channel to a connection-sharing downstream
725 * rather than handling it ourself.
731 * Stash the peer address we were given in its original text form.
733 xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL;
734 xconn->peer_port = peerport;
739 void x11_close(struct X11Connection *xconn)
744 if (xconn->auth_protocol) {
745 sfree(xconn->auth_protocol);
746 sfree(xconn->auth_data);
752 sfree(xconn->peer_addr);
756 void x11_unthrottle(struct X11Connection *xconn)
761 xconn->throttled = 0;
763 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
766 void x11_override_throttle(struct X11Connection *xconn, int enable)
771 xconn->throttle_override = enable;
773 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
776 static void x11_send_init_error(struct X11Connection *xconn,
777 const char *err_message)
781 unsigned char *reply;
783 full_message = dupprintf("%s X11 proxy: %s\n", appname, err_message);
785 msglen = strlen(full_message);
786 reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
787 msgsize = (msglen + 3) & ~3;
788 reply[0] = 0; /* failure */
789 reply[1] = msglen; /* length of reason string */
790 memcpy(reply + 2, xconn->firstpkt + 2, 4); /* major/minor proto vsn */
791 PUT_16BIT(xconn->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
792 memset(reply + 8, 0, msgsize);
793 memcpy(reply + 8, full_message, msglen);
794 sshfwd_write(xconn->c, (char *)reply, 8 + msgsize);
795 sshfwd_write_eof(xconn->c);
796 xconn->no_data_sent_to_x_client = FALSE;
801 static int x11_parse_ip(const char *addr_string, unsigned long *ip)
805 * See if we can make sense of this string as an IPv4 address, for
806 * XDM-AUTHORIZATION-1 purposes.
810 4 == sscanf(addr_string, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
811 *ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
819 * Called to send data down the raw connection.
821 int x11_send(struct X11Connection *xconn, char *data, int len)
827 * Read the first packet.
829 while (len > 0 && xconn->data_read < 12)
830 xconn->firstpkt[xconn->data_read++] = (unsigned char) (len--, *data++);
831 if (xconn->data_read < 12)
835 * If we have not allocated the auth_protocol and auth_data
836 * strings, do so now.
838 if (!xconn->auth_protocol) {
839 xconn->auth_plen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 6);
840 xconn->auth_dlen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 8);
841 xconn->auth_psize = (xconn->auth_plen + 3) & ~3;
842 xconn->auth_dsize = (xconn->auth_dlen + 3) & ~3;
843 /* Leave room for a terminating zero, to make our lives easier. */
844 xconn->auth_protocol = snewn(xconn->auth_psize + 1, char);
845 xconn->auth_data = snewn(xconn->auth_dsize, unsigned char);
849 * Read the auth_protocol and auth_data strings.
852 xconn->data_read < 12 + xconn->auth_psize)
853 xconn->auth_protocol[xconn->data_read++ - 12] = (len--, *data++);
855 xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
856 xconn->auth_data[xconn->data_read++ - 12 -
857 xconn->auth_psize] = (unsigned char) (len--, *data++);
858 if (xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
862 * If we haven't verified the authorisation, do so now.
864 if (!xconn->verified) {
866 struct X11FakeAuth *auth_matched = NULL;
867 unsigned long peer_ip;
869 int protomajor, protominor;
872 unsigned char *socketdata;
874 char new_peer_addr[32];
877 protomajor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 2);
878 protominor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 4);
882 xconn->auth_protocol[xconn->auth_plen] = '\0'; /* ASCIZ */
884 peer_ip = 0; /* placate optimiser */
885 if (x11_parse_ip(xconn->peer_addr, &peer_ip))
886 peer_port = xconn->peer_port;
888 peer_port = -1; /* signal no peer address data available */
890 err = x11_verify(peer_ip, peer_port,
891 xconn->authtree, xconn->auth_protocol,
892 xconn->auth_data, xconn->auth_dlen, &auth_matched);
894 x11_send_init_error(xconn, err);
897 assert(auth_matched);
900 * If this auth points to a connection-sharing downstream
901 * rather than an X display we know how to connect to
902 * directly, pass it off to the sharing module now.
904 if (auth_matched->share_cs) {
905 sshfwd_x11_sharing_handover(xconn->c, auth_matched->share_cs,
906 auth_matched->share_chan,
907 xconn->peer_addr, xconn->peer_port,
909 protomajor, protominor, data, len);
914 * Now we know we're going to accept the connection, and what
915 * X display to connect to. Actually connect to it.
917 sshfwd_x11_is_local(xconn->c);
918 xconn->disp = auth_matched->disp;
919 xconn->s = new_connection(sk_addr_dup(xconn->disp->addr),
920 xconn->disp->realhost, xconn->disp->port,
921 0, 1, 0, 0, (Plug) xconn,
922 sshfwd_get_conf(xconn->c));
923 if ((err = sk_socket_error(xconn->s)) != NULL) {
924 char *err_message = dupprintf("unable to connect to"
925 " forwarded X server: %s", err);
926 x11_send_init_error(xconn, err_message);
932 * Write a new connection header containing our replacement
936 socketdata = sk_getxdmdata(xconn->s, &socketdatalen);
937 if (socketdata && socketdatalen==6) {
938 sprintf(new_peer_addr, "%d.%d.%d.%d", socketdata[0],
939 socketdata[1], socketdata[2], socketdata[3]);
940 new_peer_port = GET_16BIT_MSB_FIRST(socketdata + 4);
942 strcpy(new_peer_addr, "0.0.0.0");
946 greeting = x11_make_greeting(xconn->firstpkt[0],
947 protomajor, protominor,
948 xconn->disp->localauthproto,
949 xconn->disp->localauthdata,
950 xconn->disp->localauthdatalen,
951 new_peer_addr, new_peer_port,
954 sk_write(xconn->s, greeting, greeting_len);
956 smemclr(greeting, greeting_len);
966 * After initialisation, just copy data simply.
969 return sk_write(xconn->s, data, len);
972 void x11_send_eof(struct X11Connection *xconn)
975 sk_write_eof(xconn->s);
978 * If EOF is received from the X client before we've got to
979 * the point of actually connecting to an X server, then we
980 * should send an EOF back to the client so that the
981 * forwarded channel will be terminated.
984 sshfwd_write_eof(xconn->c);
989 * Utility functions used by connection sharing to convert textual
990 * representations of an X11 auth protocol name + hex cookie into our
991 * usual integer protocol id and binary auth data.
993 int x11_identify_auth_proto(const char *protoname)
997 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
998 if (!strcmp(protoname, x11_authnames[protocol]))
1003 void *x11_dehexify(const char *hex, int *outlen)
1008 len = strlen(hex) / 2;
1009 ret = snewn(len, unsigned char);
1011 for (i = 0; i < len; i++) {
1014 bytestr[0] = hex[2*i];
1015 bytestr[1] = hex[2*i+1];
1017 sscanf(bytestr, "%x", &val);
1026 * Construct an X11 greeting packet, including making up the right
1027 * authorisation data.
1029 void *x11_make_greeting(int endian, int protomajor, int protominor,
1030 int auth_proto, const void *auth_data, int auth_len,
1031 const char *peer_addr, int peer_port,
1034 unsigned char *greeting;
1035 unsigned char realauthdata[64];
1036 const char *authname;
1037 const unsigned char *authdata;
1038 int authnamelen, authnamelen_pad;
1039 int authdatalen, authdatalen_pad;
1042 authname = x11_authnames[auth_proto];
1043 authnamelen = strlen(authname);
1044 authnamelen_pad = (authnamelen + 3) & ~3;
1046 if (auth_proto == X11_MIT) {
1047 authdata = auth_data;
1048 authdatalen = auth_len;
1049 } else if (auth_proto == X11_XDM && auth_len == 16) {
1051 unsigned long peer_ip = 0;
1053 x11_parse_ip(peer_addr, &peer_ip);
1055 authdata = realauthdata;
1057 memset(realauthdata, 0, authdatalen);
1058 memcpy(realauthdata, auth_data, 8);
1059 PUT_32BIT_MSB_FIRST(realauthdata+8, peer_ip);
1060 PUT_16BIT_MSB_FIRST(realauthdata+12, peer_port);
1062 PUT_32BIT_MSB_FIRST(realauthdata+14, t);
1064 des_encrypt_xdmauth((const unsigned char *)auth_data + 9,
1065 realauthdata, authdatalen);
1067 authdata = realauthdata;
1071 authdatalen_pad = (authdatalen + 3) & ~3;
1072 greeting_len = 12 + authnamelen_pad + authdatalen_pad;
1074 greeting = snewn(greeting_len, unsigned char);
1075 memset(greeting, 0, greeting_len);
1076 greeting[0] = endian;
1077 PUT_16BIT(endian, greeting+2, protomajor);
1078 PUT_16BIT(endian, greeting+4, protominor);
1079 PUT_16BIT(endian, greeting+6, authnamelen);
1080 PUT_16BIT(endian, greeting+8, authdatalen);
1081 memcpy(greeting+12, authname, authnamelen);
1082 memcpy(greeting+12+authnamelen_pad, authdata, authdatalen);
1084 smemclr(realauthdata, sizeof(realauthdata));
1086 *outlen = greeting_len;