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 const 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 (((unsigned long)t - (unsigned long)tim
424 + XDM_MAXSKEW) > 2*XDM_MAXSKEW)
425 return "XDM-AUTHORIZATION-1 time stamp was too far out";
426 seen = snew(struct XDMSeen);
428 memcpy(seen->clientid, data+8, 6);
429 assert(auth->xdmseen != NULL);
430 ret = add234(auth->xdmseen, seen);
433 return "XDM-AUTHORIZATION-1 data replayed";
435 /* While we're here, purge entries too old to be replayed. */
437 seen = index234(auth->xdmseen, 0);
438 assert(seen != NULL);
439 if (t - seen->time <= XDM_MAXSKEW)
441 sfree(delpos234(auth->xdmseen, 0));
444 /* implement other protocols here if ever required */
450 void x11_get_auth_from_authfile(struct X11Display *disp,
451 const char *authfilename)
454 char *buf, *ptr, *str[4];
456 int family, protocol;
457 int ideal_match = FALSE;
461 * Normally we should look for precisely the details specified in
462 * `disp'. However, there's an oddity when the display is local:
463 * displays like "localhost:0" usually have their details stored
464 * in a Unix-domain-socket record (even if there isn't actually a
465 * real Unix-domain socket available, as with OpenSSH's proxy X11
468 * This is apparently a fudge to get round the meaninglessness of
469 * "localhost" in a shared-home-directory context -- xauth entries
470 * for Unix-domain sockets already disambiguate this by storing
471 * the *local* hostname in the conveniently-blank hostname field,
472 * but IP "localhost" records couldn't do this. So, typically, an
473 * IP "localhost" entry in the auth database isn't present and if
474 * it were it would be ignored.
476 * However, we don't entirely trust that (say) Windows X servers
477 * won't rely on a straight "localhost" entry, bad idea though
478 * that is; so if we can't find a Unix-domain-socket entry we'll
479 * fall back to an IP-based entry if we can find one.
481 int localhost = !disp->unixdomain && sk_address_is_local(disp->addr);
483 authfp = fopen(authfilename, "rb");
487 ourhostname = get_hostname();
489 /* Records in .Xauthority contain four strings of up to 64K each */
490 buf = snewn(65537 * 4, char);
492 while (!ideal_match) {
493 int c, i, j, match = FALSE;
495 #define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0)
496 /* Expect a big-endian 2-byte number giving address family */
498 GET; family = (family << 8) | c;
499 /* Then expect four strings, each composed of a big-endian 2-byte
500 * length field followed by that many bytes of data */
502 for (i = 0; i < 4; i++) {
504 GET; len[i] = (len[i] << 8) | c;
506 for (j = 0; j < len[i]; j++) {
514 * Now we have a full X authority record in memory. See
515 * whether it matches the display we're trying to
518 * The details we've just read should be interpreted as
521 * - 'family' is the network address family used to
522 * connect to the display. 0 means IPv4; 6 means IPv6;
523 * 256 means Unix-domain sockets.
525 * - str[0] is the network address itself. For IPv4 and
526 * IPv6, this is a string of binary data of the
527 * appropriate length (respectively 4 and 16 bytes)
528 * representing the address in big-endian format, e.g.
529 * 7F 00 00 01 means IPv4 localhost. For Unix-domain
530 * sockets, this is the host name of the machine on
531 * which the Unix-domain display resides (so that an
532 * .Xauthority file on a shared file system can contain
533 * authority entries for Unix-domain displays on
534 * several machines without them clashing).
536 * - str[1] is the display number. I've no idea why
537 * .Xauthority stores this as a string when it has a
538 * perfectly good integer format, but there we go.
540 * - str[2] is the authorisation method, encoded as its
541 * canonical string name (i.e. "MIT-MAGIC-COOKIE-1",
542 * "XDM-AUTHORIZATION-1" or something we don't
545 * - str[3] is the actual authorisation data, stored in
549 if (disp->displaynum < 0 || disp->displaynum != atoi(str[1]))
550 continue; /* not the one */
552 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
553 if (!strcmp(str[2], x11_authnames[protocol]))
555 if (protocol == lenof(x11_authnames))
556 continue; /* don't recognise this protocol, look for another */
560 if (!disp->unixdomain &&
561 sk_addrtype(disp->addr) == ADDRTYPE_IPV4) {
563 sk_addrcopy(disp->addr, buf);
564 if (len[0] == 4 && !memcmp(str[0], buf, 4)) {
566 /* If this is a "localhost" entry, note it down
567 * but carry on looking for a Unix-domain entry. */
568 ideal_match = !localhost;
573 if (!disp->unixdomain &&
574 sk_addrtype(disp->addr) == ADDRTYPE_IPV6) {
576 sk_addrcopy(disp->addr, buf);
577 if (len[0] == 16 && !memcmp(str[0], buf, 16)) {
579 ideal_match = !localhost;
583 case 256: /* Unix-domain / localhost */
584 if ((disp->unixdomain || localhost)
585 && ourhostname && !strcmp(ourhostname, str[0]))
586 /* A matching Unix-domain socket is always the best
588 match = ideal_match = TRUE;
593 /* Current best guess -- may be overridden if !ideal_match */
594 disp->localauthproto = protocol;
595 sfree(disp->localauthdata); /* free previous guess, if any */
596 disp->localauthdata = snewn(len[3], unsigned char);
597 memcpy(disp->localauthdata, str[3], len[3]);
598 disp->localauthdatalen = len[3];
604 smemclr(buf, 65537 * 4);
609 static void x11_log(Plug p, int type, SockAddr addr, int port,
610 const char *error_msg, int error_code)
612 /* We have no interface to the logging module here, so we drop these. */
615 static void x11_send_init_error(struct X11Connection *conn,
616 const char *err_message);
618 static int x11_closing(Plug plug, const char *error_msg, int error_code,
621 struct X11Connection *xconn = (struct X11Connection *) plug;
625 * Socket error. If we're still at the connection setup stage,
626 * construct an X11 error packet passing on the problem.
628 if (xconn->no_data_sent_to_x_client) {
629 char *err_message = dupprintf("unable to connect to forwarded "
630 "X server: %s", error_msg);
631 x11_send_init_error(xconn, err_message);
636 * Whether we did that or not, now we slam the connection
639 sshfwd_unclean_close(xconn->c, error_msg);
642 * Ordinary EOF received on socket. Send an EOF on the SSH
646 sshfwd_write_eof(xconn->c);
652 static int x11_receive(Plug plug, int urgent, char *data, int len)
654 struct X11Connection *xconn = (struct X11Connection *) plug;
656 if (sshfwd_write(xconn->c, data, len) > 0) {
657 xconn->throttled = 1;
658 xconn->no_data_sent_to_x_client = FALSE;
659 sk_set_frozen(xconn->s, 1);
665 static void x11_sent(Plug plug, int bufsize)
667 struct X11Connection *xconn = (struct X11Connection *) plug;
669 sshfwd_unthrottle(xconn->c, bufsize);
673 * When setting up X forwarding, we should send the screen number
674 * from the specified local display. This function extracts it from
675 * the display string.
677 int x11_get_screen_number(char *display)
681 n = host_strcspn(display, ":");
684 n = strcspn(display, ".");
687 return atoi(display + n + 1);
691 * Called to set up the X11Connection structure, though this does not
692 * yet connect to an actual server.
694 struct X11Connection *x11_init(tree234 *authtree, void *c,
695 const char *peeraddr, int peerport)
697 static const struct plug_function_table fn_table = {
705 struct X11Connection *xconn;
710 xconn = snew(struct X11Connection);
711 xconn->fn = &fn_table;
712 xconn->auth_protocol = NULL;
713 xconn->authtree = authtree;
715 xconn->data_read = 0;
716 xconn->throttled = xconn->throttle_override = 0;
717 xconn->no_data_sent_to_x_client = TRUE;
721 * We don't actually open a local socket to the X server just yet,
722 * because we don't know which one it is. Instead, we'll wait
723 * until we see the incoming authentication data, which may tell
724 * us what display to connect to, or whether we have to divert
725 * this X forwarding channel to a connection-sharing downstream
726 * rather than handling it ourself.
732 * Stash the peer address we were given in its original text form.
734 xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL;
735 xconn->peer_port = peerport;
740 void x11_close(struct X11Connection *xconn)
745 if (xconn->auth_protocol) {
746 sfree(xconn->auth_protocol);
747 sfree(xconn->auth_data);
753 sfree(xconn->peer_addr);
757 void x11_unthrottle(struct X11Connection *xconn)
762 xconn->throttled = 0;
764 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
767 void x11_override_throttle(struct X11Connection *xconn, int enable)
772 xconn->throttle_override = enable;
774 sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
777 static void x11_send_init_error(struct X11Connection *xconn,
778 const char *err_message)
782 unsigned char *reply;
784 full_message = dupprintf("%s X11 proxy: %s\n", appname, err_message);
786 msglen = strlen(full_message);
787 reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
788 msgsize = (msglen + 3) & ~3;
789 reply[0] = 0; /* failure */
790 reply[1] = msglen; /* length of reason string */
791 memcpy(reply + 2, xconn->firstpkt + 2, 4); /* major/minor proto vsn */
792 PUT_16BIT(xconn->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
793 memset(reply + 8, 0, msgsize);
794 memcpy(reply + 8, full_message, msglen);
795 sshfwd_write(xconn->c, (char *)reply, 8 + msgsize);
796 sshfwd_write_eof(xconn->c);
797 xconn->no_data_sent_to_x_client = FALSE;
802 static int x11_parse_ip(const char *addr_string, unsigned long *ip)
806 * See if we can make sense of this string as an IPv4 address, for
807 * XDM-AUTHORIZATION-1 purposes.
811 4 == sscanf(addr_string, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
812 *ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
820 * Called to send data down the raw connection.
822 int x11_send(struct X11Connection *xconn, char *data, int len)
828 * Read the first packet.
830 while (len > 0 && xconn->data_read < 12)
831 xconn->firstpkt[xconn->data_read++] = (unsigned char) (len--, *data++);
832 if (xconn->data_read < 12)
836 * If we have not allocated the auth_protocol and auth_data
837 * strings, do so now.
839 if (!xconn->auth_protocol) {
840 xconn->auth_plen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 6);
841 xconn->auth_dlen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 8);
842 xconn->auth_psize = (xconn->auth_plen + 3) & ~3;
843 xconn->auth_dsize = (xconn->auth_dlen + 3) & ~3;
844 /* Leave room for a terminating zero, to make our lives easier. */
845 xconn->auth_protocol = snewn(xconn->auth_psize + 1, char);
846 xconn->auth_data = snewn(xconn->auth_dsize, unsigned char);
850 * Read the auth_protocol and auth_data strings.
853 xconn->data_read < 12 + xconn->auth_psize)
854 xconn->auth_protocol[xconn->data_read++ - 12] = (len--, *data++);
856 xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
857 xconn->auth_data[xconn->data_read++ - 12 -
858 xconn->auth_psize] = (unsigned char) (len--, *data++);
859 if (xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
863 * If we haven't verified the authorisation, do so now.
865 if (!xconn->verified) {
867 struct X11FakeAuth *auth_matched = NULL;
868 unsigned long peer_ip;
870 int protomajor, protominor;
873 unsigned char *socketdata;
875 char new_peer_addr[32];
878 protomajor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 2);
879 protominor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 4);
883 xconn->auth_protocol[xconn->auth_plen] = '\0'; /* ASCIZ */
885 peer_ip = 0; /* placate optimiser */
886 if (x11_parse_ip(xconn->peer_addr, &peer_ip))
887 peer_port = xconn->peer_port;
889 peer_port = -1; /* signal no peer address data available */
891 err = x11_verify(peer_ip, peer_port,
892 xconn->authtree, xconn->auth_protocol,
893 xconn->auth_data, xconn->auth_dlen, &auth_matched);
895 x11_send_init_error(xconn, err);
898 assert(auth_matched);
901 * If this auth points to a connection-sharing downstream
902 * rather than an X display we know how to connect to
903 * directly, pass it off to the sharing module now.
905 if (auth_matched->share_cs) {
906 sshfwd_x11_sharing_handover(xconn->c, auth_matched->share_cs,
907 auth_matched->share_chan,
908 xconn->peer_addr, xconn->peer_port,
910 protomajor, protominor, data, len);
915 * Now we know we're going to accept the connection, and what
916 * X display to connect to. Actually connect to it.
918 sshfwd_x11_is_local(xconn->c);
919 xconn->disp = auth_matched->disp;
920 xconn->s = new_connection(sk_addr_dup(xconn->disp->addr),
921 xconn->disp->realhost, xconn->disp->port,
922 0, 1, 0, 0, (Plug) xconn,
923 sshfwd_get_conf(xconn->c));
924 if ((err = sk_socket_error(xconn->s)) != NULL) {
925 char *err_message = dupprintf("unable to connect to"
926 " forwarded X server: %s", err);
927 x11_send_init_error(xconn, err_message);
933 * Write a new connection header containing our replacement
937 socketdata = sk_getxdmdata(xconn->s, &socketdatalen);
938 if (socketdata && socketdatalen==6) {
939 sprintf(new_peer_addr, "%d.%d.%d.%d", socketdata[0],
940 socketdata[1], socketdata[2], socketdata[3]);
941 new_peer_port = GET_16BIT_MSB_FIRST(socketdata + 4);
943 strcpy(new_peer_addr, "0.0.0.0");
947 greeting = x11_make_greeting(xconn->firstpkt[0],
948 protomajor, protominor,
949 xconn->disp->localauthproto,
950 xconn->disp->localauthdata,
951 xconn->disp->localauthdatalen,
952 new_peer_addr, new_peer_port,
955 sk_write(xconn->s, greeting, greeting_len);
957 smemclr(greeting, greeting_len);
967 * After initialisation, just copy data simply.
970 return sk_write(xconn->s, data, len);
973 void x11_send_eof(struct X11Connection *xconn)
976 sk_write_eof(xconn->s);
979 * If EOF is received from the X client before we've got to
980 * the point of actually connecting to an X server, then we
981 * should send an EOF back to the client so that the
982 * forwarded channel will be terminated.
985 sshfwd_write_eof(xconn->c);
990 * Utility functions used by connection sharing to convert textual
991 * representations of an X11 auth protocol name + hex cookie into our
992 * usual integer protocol id and binary auth data.
994 int x11_identify_auth_proto(const char *protoname)
998 for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
999 if (!strcmp(protoname, x11_authnames[protocol]))
1004 void *x11_dehexify(const char *hex, int *outlen)
1009 len = strlen(hex) / 2;
1010 ret = snewn(len, unsigned char);
1012 for (i = 0; i < len; i++) {
1015 bytestr[0] = hex[2*i];
1016 bytestr[1] = hex[2*i+1];
1018 sscanf(bytestr, "%x", &val);
1027 * Construct an X11 greeting packet, including making up the right
1028 * authorisation data.
1030 void *x11_make_greeting(int endian, int protomajor, int protominor,
1031 int auth_proto, const void *auth_data, int auth_len,
1032 const char *peer_addr, int peer_port,
1035 unsigned char *greeting;
1036 unsigned char realauthdata[64];
1037 const char *authname;
1038 const unsigned char *authdata;
1039 int authnamelen, authnamelen_pad;
1040 int authdatalen, authdatalen_pad;
1043 authname = x11_authnames[auth_proto];
1044 authnamelen = strlen(authname);
1045 authnamelen_pad = (authnamelen + 3) & ~3;
1047 if (auth_proto == X11_MIT) {
1048 authdata = auth_data;
1049 authdatalen = auth_len;
1050 } else if (auth_proto == X11_XDM && auth_len == 16) {
1052 unsigned long peer_ip = 0;
1054 x11_parse_ip(peer_addr, &peer_ip);
1056 authdata = realauthdata;
1058 memset(realauthdata, 0, authdatalen);
1059 memcpy(realauthdata, auth_data, 8);
1060 PUT_32BIT_MSB_FIRST(realauthdata+8, peer_ip);
1061 PUT_16BIT_MSB_FIRST(realauthdata+12, peer_port);
1063 PUT_32BIT_MSB_FIRST(realauthdata+14, t);
1065 des_encrypt_xdmauth((const unsigned char *)auth_data + 9,
1066 realauthdata, authdatalen);
1068 authdata = realauthdata;
1072 authdatalen_pad = (authdatalen + 3) & ~3;
1073 greeting_len = 12 + authnamelen_pad + authdatalen_pad;
1075 greeting = snewn(greeting_len, unsigned char);
1076 memset(greeting, 0, greeting_len);
1077 greeting[0] = endian;
1078 PUT_16BIT(endian, greeting+2, protomajor);
1079 PUT_16BIT(endian, greeting+4, protominor);
1080 PUT_16BIT(endian, greeting+6, authnamelen);
1081 PUT_16BIT(endian, greeting+8, authdatalen);
1082 memcpy(greeting+12, authname, authnamelen);
1083 memcpy(greeting+12+authnamelen_pad, authdata, authdatalen);
1085 smemclr(realauthdata, sizeof(realauthdata));
1087 *outlen = greeting_len;