9 #define GET_32BIT_LSB_FIRST(cp) \
10 (((unsigned long)(unsigned char)(cp)[0]) | \
11 ((unsigned long)(unsigned char)(cp)[1] << 8) | \
12 ((unsigned long)(unsigned char)(cp)[2] << 16) | \
13 ((unsigned long)(unsigned char)(cp)[3] << 24))
15 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
16 (cp)[0] = (char)(value), \
17 (cp)[1] = (char)((value) >> 8), \
18 (cp)[2] = (char)((value) >> 16), \
19 (cp)[3] = (char)((value) >> 24) )
21 #define GET_16BIT_LSB_FIRST(cp) \
22 (((unsigned long)(unsigned char)(cp)[0]) | \
23 ((unsigned long)(unsigned char)(cp)[1] << 8))
25 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
26 (cp)[0] = (char)(value), \
27 (cp)[1] = (char)((value) >> 8) )
29 #define GET_32BIT_MSB_FIRST(cp) \
30 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
31 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
32 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
33 ((unsigned long)(unsigned char)(cp)[3]))
35 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
36 (cp)[0] = (char)((value) >> 24), \
37 (cp)[1] = (char)((value) >> 16), \
38 (cp)[2] = (char)((value) >> 8), \
39 (cp)[3] = (char)(value) )
41 #define GET_16BIT_MSB_FIRST(cp) \
42 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
43 ((unsigned long)(unsigned char)(cp)[1]))
45 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
46 (cp)[0] = (char)((value) >> 8), \
47 (cp)[1] = (char)(value) )
49 #define GET_16BIT(endian, cp) \
50 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
52 #define PUT_16BIT(endian, cp, val) \
53 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
55 const char *const x11_authnames[] = {
56 "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
60 unsigned char fakedata[64], realdata[64];
61 int fakeproto, realproto;
66 const struct plug_function_table *fn;
67 /* the above variable absolutely *must* be the first in this structure */
68 unsigned char firstpkt[12]; /* first X data packet */
71 unsigned char *auth_data;
72 int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
74 int throttled, throttle_override;
75 unsigned long peer_ip;
77 void *c; /* data used by ssh.c */
81 void *x11_invent_auth(char *proto, int protomaxlen,
82 char *data, int datamaxlen, int proto_id)
84 struct X11Auth *auth = smalloc(sizeof(struct X11Auth));
88 if (proto_id == X11_MIT) {
89 auth->fakeproto = X11_MIT;
91 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
93 for (i = 0; i < 16; i++)
94 auth->fakedata[i] = random_byte();
96 assert(proto_id == X11_XDM);
97 auth->fakeproto = X11_XDM;
99 /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
101 for (i = 0; i < 16; i++)
102 auth->fakedata[i] = (i == 8 ? 0 : random_byte());
105 /* Now format for the recipient. */
106 strncpy(proto, x11_authnames[auth->fakeproto], protomaxlen);
108 for (i = 0; i < auth->fakelen; i++)
109 sprintf(ourdata + strlen(ourdata), "%02x", auth->fakedata[i]);
110 strncpy(data, ourdata, datamaxlen);
116 * Fetch the real auth data for a given display string, and store
117 * it in an X11Auth structure. Returns NULL on success, or an error
120 void x11_get_real_auth(void *authv, char *display)
122 struct X11Auth *auth = (struct X11Auth *)authv;
124 auth->realproto = X11_NO_AUTH; /* in case next call does nothing */
126 auth->reallen = sizeof(auth->realdata);
127 platform_get_x11_auth(display, &auth->realproto,
128 auth->realdata, &auth->reallen);
131 static char *x11_verify(unsigned long peer_ip, int peer_port,
132 struct X11Auth *auth, char *proto,
133 unsigned char *data, int dlen)
135 if (strcmp(proto, x11_authnames[auth->fakeproto]) != 0)
136 return "wrong authentication protocol attempted";
137 if (auth->fakeproto == X11_MIT) {
138 if (dlen != auth->fakelen)
139 return "MIT-MAGIC-COOKIE-1 data was wrong length";
140 if (memcmp(auth->fakedata, data, dlen) != 0)
141 return "MIT-MAGIC-COOKIE-1 data did not match";
143 if (auth->fakeproto == X11_XDM) {
149 return "XDM-AUTHORIZATION-1 data was wrong length";
151 return "cannot do XDM-AUTHORIZATION-1 without remote address data";
152 des_decrypt_xdmauth(auth->fakedata+9, data, 24);
153 if (memcmp(auth->fakedata, data, 8) != 0)
154 return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
155 if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
156 return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
157 if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
158 return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
159 t = GET_32BIT_MSB_FIRST(data+14);
160 for (i = 18; i < 24; i++)
161 if (data[i] != 0) /* zero padding wrong */
162 return "XDM-AUTHORIZATION-1 data failed check";
164 if (abs(t - tim) > 20*60) /* 20 minute clock skew should be OK */
165 return "XDM-AUTHORIZATION-1 time stamp was too far out";
167 /* implement other protocols here if ever required */
171 static int x11_closing(Plug plug, char *error_msg, int error_code,
174 struct X11Private *pr = (struct X11Private *) plug;
177 * We have no way to communicate down the forwarded connection,
178 * so if an error occurred on the socket, we just ignore it
179 * and treat it like a proper close.
186 static int x11_receive(Plug plug, int urgent, char *data, int len)
188 struct X11Private *pr = (struct X11Private *) plug;
190 if (sshfwd_write(pr->c, data, len) > 0) {
192 sk_set_frozen(pr->s, 1);
198 static void x11_sent(Plug plug, int bufsize)
200 struct X11Private *pr = (struct X11Private *) plug;
202 sshfwd_unthrottle(pr->c, bufsize);
206 * When setting up X forwarding, we should send the screen number
207 * from the specified local display. This function extracts it from
208 * the display string.
210 int x11_get_screen_number(char *display)
214 n = strcspn(display, ":");
217 n = strcspn(display, ".");
220 return atoi(display + n + 1);
224 * Called to set up the raw connection.
226 * Returns an error message, or NULL on success.
227 * also, fills the SocketsStructure
229 char *x11_init(Socket * s, char *display, void *c, void *auth,
230 const char *peeraddr, int peerport, const Config *cfg)
232 static const struct plug_function_table fn_table = {
241 char *err, *dummy_realhost;
244 struct X11Private *pr;
247 * Split up display name into host and display-number parts.
249 n = strcspn(display, ":");
251 displaynum = atoi(display + n + 1);
253 displaynum = 0; /* sensible default */
254 if (n > sizeof(host) - 1)
255 n = sizeof(host) - 1;
257 strncpy(host, display, n);
261 * Local display numbers, particularly on Unix, often omit
262 * the display part completely.
264 strcpy(host, "localhost");
267 port = 6000 + displaynum;
272 addr = name_lookup(host, port, &dummy_realhost, cfg);
273 if ((err = sk_addr_error(addr)) != NULL)
279 pr = (struct X11Private *) smalloc(sizeof(struct X11Private));
281 pr->auth_protocol = NULL;
282 pr->auth = (struct X11Auth *)auth;
285 pr->throttled = pr->throttle_override = 0;
288 pr->s = *s = new_connection(addr, dummy_realhost, port,
289 0, 1, 0, (Plug) pr, cfg);
290 if ((err = sk_socket_error(*s)) != NULL) {
296 * See if we can make sense of the peer address we were given.
301 4 == sscanf(peeraddr, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
302 pr->peer_ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
303 pr->peer_port = peerport;
310 sk_set_private_ptr(*s, pr);
315 void x11_close(Socket s)
317 struct X11Private *pr;
320 pr = (struct X11Private *) sk_get_private_ptr(s);
321 if (pr->auth_protocol) {
322 sfree(pr->auth_protocol);
323 sfree(pr->auth_data);
331 void x11_unthrottle(Socket s)
333 struct X11Private *pr;
336 pr = (struct X11Private *) sk_get_private_ptr(s);
339 sk_set_frozen(s, pr->throttled || pr->throttle_override);
342 void x11_override_throttle(Socket s, int enable)
344 struct X11Private *pr;
347 pr = (struct X11Private *) sk_get_private_ptr(s);
349 pr->throttle_override = enable;
350 sk_set_frozen(s, pr->throttled || pr->throttle_override);
354 * Called to send data down the raw connection.
356 int x11_send(Socket s, char *data, int len)
358 struct X11Private *pr = (struct X11Private *) sk_get_private_ptr(s);
364 * Read the first packet.
366 while (len > 0 && pr->data_read < 12)
367 pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++);
368 if (pr->data_read < 12)
372 * If we have not allocated the auth_protocol and auth_data
373 * strings, do so now.
375 if (!pr->auth_protocol) {
376 pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6);
377 pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8);
378 pr->auth_psize = (pr->auth_plen + 3) & ~3;
379 pr->auth_dsize = (pr->auth_dlen + 3) & ~3;
380 /* Leave room for a terminating zero, to make our lives easier. */
381 pr->auth_protocol = (char *) smalloc(pr->auth_psize + 1);
382 pr->auth_data = (unsigned char *) smalloc(pr->auth_dsize);
386 * Read the auth_protocol and auth_data strings.
388 while (len > 0 && pr->data_read < 12 + pr->auth_psize)
389 pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
390 while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
391 pr->auth_data[pr->data_read++ - 12 -
392 pr->auth_psize] = (unsigned char) (len--, *data++);
393 if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
397 * If we haven't verified the authentication, do so now.
402 pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
403 err = x11_verify(pr->peer_ip, pr->peer_port,
404 pr->auth, pr->auth_protocol,
405 pr->auth_data, pr->auth_dlen);
408 * If authentication failed, construct and send an error
409 * packet, then terminate the connection.
414 unsigned char *reply;
416 message = dupprintf("PuTTY X11 proxy: %s", err);
417 msglen = strlen(message);
418 reply = smalloc(8 + msglen+1 + 4); /* include zero byte */
419 msgsize = (msglen + 3) & ~3;
420 reply[0] = 0; /* failure */
421 reply[1] = msglen; /* length of reason string */
422 memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */
423 PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
424 memset(reply + 8, 0, msgsize);
425 memcpy(reply + 8, message, msglen);
426 sshfwd_write(pr->c, (char *)reply, 8 + msgsize);
435 * Now we know we're going to accept the connection. Strip
436 * the fake auth data, and optionally put real auth data in
440 char realauthdata[64];
442 int authstrlen = strlen(x11_authnames[pr->auth->realproto]);
445 static const char zeroes[4] = { 0,0,0,0 };
447 if (pr->auth->realproto == X11_MIT) {
448 assert(pr->auth->reallen <= lenof(realauthdata));
449 realauthlen = pr->auth->reallen;
450 memcpy(realauthdata, pr->auth->realdata, realauthlen);
451 } else if (pr->auth->realproto == X11_XDM &&
452 pr->auth->reallen == 16 &&
453 sk_getxdmdata(s, &ip, &port)) {
456 memset(realauthdata, 0, 24);
457 memcpy(realauthdata, pr->auth->realdata, 8);
458 PUT_32BIT_MSB_FIRST(realauthdata+8, ip);
459 PUT_16BIT_MSB_FIRST(realauthdata+12, port);
461 PUT_32BIT_MSB_FIRST(realauthdata+14, t);
462 des_encrypt_xdmauth(pr->auth->realdata+9,
463 (unsigned char *)realauthdata, 24);
465 /* implement other auth methods here if required */
467 PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen);
468 PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen);
470 sk_write(s, (char *)pr->firstpkt, 12);
473 sk_write(s, x11_authnames[pr->auth->realproto], authstrlen);
474 sk_write(s, zeroes, 3 & (-authstrlen));
477 sk_write(s, realauthdata, realauthlen);
478 sk_write(s, zeroes, 3 & (-realauthlen));
485 * After initialisation, just copy data simply.
488 return sk_write(s, data, len);