2 * Platform-independent bits of X11 forwarding.
13 #define GET_32BIT_LSB_FIRST(cp) \
14 (((unsigned long)(unsigned char)(cp)[0]) | \
15 ((unsigned long)(unsigned char)(cp)[1] << 8) | \
16 ((unsigned long)(unsigned char)(cp)[2] << 16) | \
17 ((unsigned long)(unsigned char)(cp)[3] << 24))
19 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
20 (cp)[0] = (char)(value), \
21 (cp)[1] = (char)((value) >> 8), \
22 (cp)[2] = (char)((value) >> 16), \
23 (cp)[3] = (char)((value) >> 24) )
25 #define GET_16BIT_LSB_FIRST(cp) \
26 (((unsigned long)(unsigned char)(cp)[0]) | \
27 ((unsigned long)(unsigned char)(cp)[1] << 8))
29 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
30 (cp)[0] = (char)(value), \
31 (cp)[1] = (char)((value) >> 8) )
33 #define GET_32BIT_MSB_FIRST(cp) \
34 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
35 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
36 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
37 ((unsigned long)(unsigned char)(cp)[3]))
39 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
40 (cp)[0] = (char)((value) >> 24), \
41 (cp)[1] = (char)((value) >> 16), \
42 (cp)[2] = (char)((value) >> 8), \
43 (cp)[3] = (char)(value) )
45 #define GET_16BIT_MSB_FIRST(cp) \
46 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
47 ((unsigned long)(unsigned char)(cp)[1]))
49 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
50 (cp)[0] = (char)((value) >> 8), \
51 (cp)[1] = (char)(value) )
53 #define GET_16BIT(endian, cp) \
54 (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
56 #define PUT_16BIT(endian, cp, val) \
57 (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
59 const char *const x11_authnames
[] = {
60 "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
64 unsigned char fakedata
[64], realdata
[64];
65 int fakeproto
, realproto
;
70 const struct plug_function_table
*fn
;
71 /* the above variable absolutely *must* be the first in this structure */
72 unsigned char firstpkt
[12]; /* first X data packet */
75 unsigned char *auth_data
;
76 int data_read
, auth_plen
, auth_psize
, auth_dlen
, auth_dsize
;
78 int throttled
, throttle_override
;
79 unsigned long peer_ip
;
81 void *c
; /* data used by ssh.c */
85 void *x11_invent_auth(char *proto
, int protomaxlen
,
86 char *data
, int datamaxlen
, int proto_id
)
88 struct X11Auth
*auth
= snew(struct X11Auth
);
92 if (proto_id
== X11_MIT
) {
93 auth
->fakeproto
= X11_MIT
;
95 /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
97 for (i
= 0; i
< 16; i
++)
98 auth
->fakedata
[i
] = random_byte();
100 assert(proto_id
== X11_XDM
);
101 auth
->fakeproto
= X11_XDM
;
103 /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
105 for (i
= 0; i
< 16; i
++)
106 auth
->fakedata
[i
] = (i
== 8 ?
0 : random_byte());
109 /* Now format for the recipient. */
110 strncpy(proto
, x11_authnames
[auth
->fakeproto
], protomaxlen
);
112 for (i
= 0; i
< auth
->fakelen
; i
++)
113 sprintf(ourdata
+ strlen(ourdata
), "%02x", auth
->fakedata
[i
]);
114 strncpy(data
, ourdata
, datamaxlen
);
119 void x11_free_auth(void *auth
)
126 * Fetch the real auth data for a given display string, and store
127 * it in an X11Auth structure. Returns NULL on success, or an error
130 void x11_get_real_auth(void *authv
, char *display
)
132 struct X11Auth
*auth
= (struct X11Auth
*)authv
;
134 auth
->realproto
= X11_NO_AUTH
; /* in case next call does nothing */
136 auth
->reallen
= sizeof(auth
->realdata
);
137 platform_get_x11_auth(display
, &auth
->realproto
,
138 auth
->realdata
, &auth
->reallen
);
141 static char *x11_verify(unsigned long peer_ip
, int peer_port
,
142 struct X11Auth
*auth
, char *proto
,
143 unsigned char *data
, int dlen
)
145 if (strcmp(proto
, x11_authnames
[auth
->fakeproto
]) != 0)
146 return "wrong authentication protocol attempted";
147 if (auth
->fakeproto
== X11_MIT
) {
148 if (dlen
!= auth
->fakelen
)
149 return "MIT-MAGIC-COOKIE-1 data was wrong length";
150 if (memcmp(auth
->fakedata
, data
, dlen
) != 0)
151 return "MIT-MAGIC-COOKIE-1 data did not match";
153 if (auth
->fakeproto
== X11_XDM
) {
159 return "XDM-AUTHORIZATION-1 data was wrong length";
161 return "cannot do XDM-AUTHORIZATION-1 without remote address data";
162 des_decrypt_xdmauth(auth
->fakedata
+9, data
, 24);
163 if (memcmp(auth
->fakedata
, data
, 8) != 0)
164 return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
165 if (GET_32BIT_MSB_FIRST(data
+8) != peer_ip
)
166 return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
167 if ((int)GET_16BIT_MSB_FIRST(data
+12) != peer_port
)
168 return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
169 t
= GET_32BIT_MSB_FIRST(data
+14);
170 for (i
= 18; i
< 24; i
++)
171 if (data
[i
] != 0) /* zero padding wrong */
172 return "XDM-AUTHORIZATION-1 data failed check";
174 if (abs(t
- tim
) > 20*60) /* 20 minute clock skew should be OK */
175 return "XDM-AUTHORIZATION-1 time stamp was too far out";
177 /* implement other protocols here if ever required */
181 static int x11_closing(Plug plug
, const char *error_msg
, int error_code
,
184 struct X11Private
*pr
= (struct X11Private
*) plug
;
187 * We have no way to communicate down the forwarded connection,
188 * so if an error occurred on the socket, we just ignore it
189 * and treat it like a proper close.
196 static int x11_receive(Plug plug
, int urgent
, char *data
, int len
)
198 struct X11Private
*pr
= (struct X11Private
*) plug
;
200 if (sshfwd_write(pr
->c
, data
, len
) > 0) {
202 sk_set_frozen(pr
->s
, 1);
208 static void x11_sent(Plug plug
, int bufsize
)
210 struct X11Private
*pr
= (struct X11Private
*) plug
;
212 sshfwd_unthrottle(pr
->c
, bufsize
);
216 * When setting up X forwarding, we should send the screen number
217 * from the specified local display. This function extracts it from
218 * the display string.
220 int x11_get_screen_number(char *display
)
224 n
= strcspn(display
, ":");
227 n
= strcspn(display
, ".");
230 return atoi(display
+ n
+ 1);
233 /* Find the right display, returns an allocated string */
234 char *x11_display(const char *display
) {
236 if(!display
|| !*display
) {
237 /* try to find platform-specific local display */
238 if(!(ret
= platform_get_x_display()))
239 /* plausible default for all platforms */
242 ret
= dupstr(display
);
244 /* no transport specified, use whatever we think is best */
245 char *s
= dupcat(platform_x11_best_transport
, display
, (char *)0);
253 * Called to set up the raw connection.
255 * Returns an error message, or NULL on success.
256 * also, fills the SocketsStructure
258 const char *x11_init(Socket
* s
, char *display
, void *c
, void *auth
,
259 const char *peeraddr
, int peerport
, const Config
*cfg
)
261 static const struct plug_function_table fn_table
= {
271 char *dummy_realhost
;
274 struct X11Private
*pr
;
276 /* default display */
277 display
= x11_display(display
);
279 * Split up display name into host and display-number parts.
281 n
= strcspn(display
, ":");
282 assert(n
!= 0); /* x11_display() promises this */
284 displaynum
= atoi(display
+ n
+ 1);
286 displaynum
= 0; /* sensible default */
287 if (n
> sizeof(host
) - 1)
288 n
= sizeof(host
) - 1;
289 strncpy(host
, display
, n
);
293 if(!strcmp(host
, "unix")) {
294 /* use AF_UNIX sockets (doesn't make sense on all platforms) */
295 addr
= platform_get_x11_unix_address(displaynum
,
297 port
= 0; /* to show we are not confused */
299 port
= 6000 + displaynum
;
304 addr
= name_lookup(host
, port
, &dummy_realhost
, cfg
);
305 if ((err
= sk_addr_error(addr
)) != NULL
) {
314 pr
= snew(struct X11Private
);
316 pr
->auth_protocol
= NULL
;
317 pr
->auth
= (struct X11Auth
*)auth
;
320 pr
->throttled
= pr
->throttle_override
= 0;
323 pr
->s
= *s
= new_connection(addr
, dummy_realhost
, port
,
324 0, 1, 0, 0, (Plug
) pr
, cfg
);
325 if ((err
= sk_socket_error(*s
)) != NULL
) {
331 * See if we can make sense of the peer address we were given.
336 4 == sscanf(peeraddr
, "%d.%d.%d.%d", i
+0, i
+1, i
+2, i
+3)) {
337 pr
->peer_ip
= (i
[0] << 24) | (i
[1] << 16) | (i
[2] << 8) | i
[3];
338 pr
->peer_port
= peerport
;
345 sk_set_private_ptr(*s
, pr
);
349 void x11_close(Socket s
)
351 struct X11Private
*pr
;
354 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
355 if (pr
->auth_protocol
) {
356 sfree(pr
->auth_protocol
);
357 sfree(pr
->auth_data
);
365 void x11_unthrottle(Socket s
)
367 struct X11Private
*pr
;
370 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
373 sk_set_frozen(s
, pr
->throttled
|| pr
->throttle_override
);
376 void x11_override_throttle(Socket s
, int enable
)
378 struct X11Private
*pr
;
381 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
383 pr
->throttle_override
= enable
;
384 sk_set_frozen(s
, pr
->throttled
|| pr
->throttle_override
);
388 * Called to send data down the raw connection.
390 int x11_send(Socket s
, char *data
, int len
)
392 struct X11Private
*pr
;
395 pr
= (struct X11Private
*) sk_get_private_ptr(s
);
398 * Read the first packet.
400 while (len
> 0 && pr
->data_read
< 12)
401 pr
->firstpkt
[pr
->data_read
++] = (unsigned char) (len
--, *data
++);
402 if (pr
->data_read
< 12)
406 * If we have not allocated the auth_protocol and auth_data
407 * strings, do so now.
409 if (!pr
->auth_protocol
) {
410 pr
->auth_plen
= GET_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 6);
411 pr
->auth_dlen
= GET_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 8);
412 pr
->auth_psize
= (pr
->auth_plen
+ 3) & ~3;
413 pr
->auth_dsize
= (pr
->auth_dlen
+ 3) & ~3;
414 /* Leave room for a terminating zero, to make our lives easier. */
415 pr
->auth_protocol
= snewn(pr
->auth_psize
+ 1, char);
416 pr
->auth_data
= snewn(pr
->auth_dsize
, unsigned char);
420 * Read the auth_protocol and auth_data strings.
422 while (len
> 0 && pr
->data_read
< 12 + pr
->auth_psize
)
423 pr
->auth_protocol
[pr
->data_read
++ - 12] = (len
--, *data
++);
424 while (len
> 0 && pr
->data_read
< 12 + pr
->auth_psize
+ pr
->auth_dsize
)
425 pr
->auth_data
[pr
->data_read
++ - 12 -
426 pr
->auth_psize
] = (unsigned char) (len
--, *data
++);
427 if (pr
->data_read
< 12 + pr
->auth_psize
+ pr
->auth_dsize
)
431 * If we haven't verified the authentication, do so now.
436 pr
->auth_protocol
[pr
->auth_plen
] = '\0'; /* ASCIZ */
437 err
= x11_verify(pr
->peer_ip
, pr
->peer_port
,
438 pr
->auth
, pr
->auth_protocol
,
439 pr
->auth_data
, pr
->auth_dlen
);
442 * If authentication failed, construct and send an error
443 * packet, then terminate the connection.
448 unsigned char *reply
;
450 message
= dupprintf("PuTTY X11 proxy: %s", err
);
451 msglen
= strlen(message
);
452 reply
= snewn(8 + msglen
+1 + 4, unsigned char); /* include zero */
453 msgsize
= (msglen
+ 3) & ~3;
454 reply
[0] = 0; /* failure */
455 reply
[1] = msglen
; /* length of reason string */
456 memcpy(reply
+ 2, pr
->firstpkt
+ 2, 4); /* major/minor proto vsn */
457 PUT_16BIT(pr
->firstpkt
[0], reply
+ 6, msgsize
>> 2);/* data len */
458 memset(reply
+ 8, 0, msgsize
);
459 memcpy(reply
+ 8, message
, msglen
);
460 sshfwd_write(pr
->c
, (char *)reply
, 8 + msgsize
);
469 * Now we know we're going to accept the connection. Strip
470 * the fake auth data, and optionally put real auth data in
474 char realauthdata
[64];
476 int authstrlen
= strlen(x11_authnames
[pr
->auth
->realproto
]);
479 static const char zeroes
[4] = { 0,0,0,0 };
481 if (pr
->auth
->realproto
== X11_MIT
) {
482 assert(pr
->auth
->reallen
<= lenof(realauthdata
));
483 realauthlen
= pr
->auth
->reallen
;
484 memcpy(realauthdata
, pr
->auth
->realdata
, realauthlen
);
485 } else if (pr
->auth
->realproto
== X11_XDM
&&
486 pr
->auth
->reallen
== 16 &&
487 sk_getxdmdata(s
, &ip
, &port
)) {
490 memset(realauthdata
, 0, 24);
491 memcpy(realauthdata
, pr
->auth
->realdata
, 8);
492 PUT_32BIT_MSB_FIRST(realauthdata
+8, ip
);
493 PUT_16BIT_MSB_FIRST(realauthdata
+12, port
);
495 PUT_32BIT_MSB_FIRST(realauthdata
+14, t
);
496 des_encrypt_xdmauth(pr
->auth
->realdata
+9,
497 (unsigned char *)realauthdata
, 24);
499 /* implement other auth methods here if required */
501 PUT_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 6, authstrlen
);
502 PUT_16BIT(pr
->firstpkt
[0], pr
->firstpkt
+ 8, realauthlen
);
504 sk_write(s
, (char *)pr
->firstpkt
, 12);
507 sk_write(s
, x11_authnames
[pr
->auth
->realproto
], authstrlen
);
508 sk_write(s
, zeroes
, 3 & (-authstrlen
));
511 sk_write(s
, realauthdata
, realauthlen
);
512 sk_write(s
, zeroes
, 3 & (-realauthlen
));
519 * After initialisation, just copy data simply.
522 return sk_write(s
, data
, len
);