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1 | #include <windows.h> |
2 | #include <stdio.h> |
3 | #include <stdlib.h> |
4 | |
5 | #include "putty.h" |
6 | #include "ssh.h" |
7 | |
8 | #ifndef FALSE |
9 | #define FALSE 0 |
10 | #endif |
11 | #ifndef TRUE |
12 | #define TRUE 1 |
13 | #endif |
14 | |
15 | #define GET_32BIT_LSB_FIRST(cp) \ |
16 | (((unsigned long)(unsigned char)(cp)[0]) | \ |
17 | ((unsigned long)(unsigned char)(cp)[1] << 8) | \ |
18 | ((unsigned long)(unsigned char)(cp)[2] << 16) | \ |
19 | ((unsigned long)(unsigned char)(cp)[3] << 24)) |
20 | |
21 | #define PUT_32BIT_LSB_FIRST(cp, value) ( \ |
22 | (cp)[0] = (value), \ |
23 | (cp)[1] = (value) >> 8, \ |
24 | (cp)[2] = (value) >> 16, \ |
25 | (cp)[3] = (value) >> 24 ) |
26 | |
27 | #define GET_16BIT_LSB_FIRST(cp) \ |
28 | (((unsigned long)(unsigned char)(cp)[0]) | \ |
29 | ((unsigned long)(unsigned char)(cp)[1] << 8)) |
30 | |
31 | #define PUT_16BIT_LSB_FIRST(cp, value) ( \ |
32 | (cp)[0] = (value), \ |
33 | (cp)[1] = (value) >> 8 ) |
34 | |
35 | #define GET_32BIT_MSB_FIRST(cp) \ |
36 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
37 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
38 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
39 | ((unsigned long)(unsigned char)(cp)[3])) |
40 | |
41 | #define PUT_32BIT_MSB_FIRST(cp, value) ( \ |
42 | (cp)[0] = (value) >> 24, \ |
43 | (cp)[1] = (value) >> 16, \ |
44 | (cp)[2] = (value) >> 8, \ |
45 | (cp)[3] = (value) ) |
46 | |
47 | #define GET_16BIT_MSB_FIRST(cp) \ |
48 | (((unsigned long)(unsigned char)(cp)[0] << 8) | \ |
49 | ((unsigned long)(unsigned char)(cp)[1])) |
50 | |
51 | #define PUT_16BIT_MSB_FIRST(cp, value) ( \ |
52 | (cp)[0] = (value) >> 8, \ |
53 | (cp)[1] = (value) ) |
54 | |
55 | #define GET_16BIT(endian, cp) \ |
56 | (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp)) |
57 | |
58 | #define PUT_16BIT(endian, cp, val) \ |
59 | (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val)) |
60 | |
61 | extern void sshfwd_close(void *); |
62 | extern void sshfwd_write(void *, char *, int); |
63 | |
64 | struct X11Private { |
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65 | struct plug_function_table *fn; |
66 | /* the above variable absolutely *must* be the first in this structure */ |
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67 | unsigned char firstpkt[12]; /* first X data packet */ |
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68 | char *auth_protocol; |
69 | unsigned char *auth_data; |
70 | int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize; |
71 | int verified; |
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72 | void *c; /* data used by ssh.c */ |
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73 | Socket s; |
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74 | }; |
75 | |
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76 | void x11_close(Socket s); |
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77 | |
78 | static unsigned char x11_authdata[64]; |
79 | static int x11_authdatalen; |
80 | |
81 | void x11_invent_auth(char *proto, int protomaxlen, |
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82 | char *data, int datamaxlen) |
83 | { |
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84 | char ourdata[64]; |
85 | int i; |
86 | |
87 | /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */ |
88 | x11_authdatalen = 16; |
89 | for (i = 0; i < 16; i++) |
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90 | x11_authdata[i] = random_byte(); |
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91 | |
92 | /* Now format for the recipient. */ |
93 | strncpy(proto, "MIT-MAGIC-COOKIE-1", protomaxlen); |
94 | ourdata[0] = '\0'; |
95 | for (i = 0; i < x11_authdatalen; i++) |
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96 | sprintf(ourdata + strlen(ourdata), "%02x", x11_authdata[i]); |
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97 | strncpy(data, ourdata, datamaxlen); |
98 | } |
99 | |
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100 | static int x11_verify(char *proto, unsigned char *data, int dlen) |
101 | { |
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102 | if (strcmp(proto, "MIT-MAGIC-COOKIE-1") != 0) |
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103 | return 0; /* wrong protocol attempted */ |
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104 | if (dlen != x11_authdatalen) |
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105 | return 0; /* cookie was wrong length */ |
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106 | if (memcmp(x11_authdata, data, dlen) != 0) |
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107 | return 0; /* cookie was wrong cookie! */ |
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108 | return 1; |
109 | } |
110 | |
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111 | static int x11_closing(Plug plug, char *error_msg, int error_code, |
112 | int calling_back) |
113 | { |
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114 | struct X11Private *pr = (struct X11Private *) plug; |
115 | |
116 | /* |
117 | * We have no way to communicate down the forwarded connection, |
118 | * so if an error occurred on the socket, we just ignore it |
119 | * and treat it like a proper close. |
120 | */ |
121 | sshfwd_close(pr->c); |
122 | x11_close(pr->s); |
123 | return 1; |
124 | } |
125 | |
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126 | static int x11_receive(Plug plug, int urgent, char *data, int len) |
127 | { |
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128 | struct X11Private *pr = (struct X11Private *) plug; |
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129 | |
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130 | sshfwd_write(pr->c, data, len); |
131 | return 1; |
132 | } |
133 | |
134 | /* |
135 | * Called to set up the raw connection. |
136 | * |
137 | * Returns an error message, or NULL on success. |
138 | * also, fills the SocketsStructure |
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139 | */ |
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140 | char *x11_init(Socket * s, char *display, void *c) |
141 | { |
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142 | static struct plug_function_table fn_table = { |
143 | x11_closing, |
144 | x11_receive |
145 | }; |
146 | |
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147 | SockAddr addr; |
148 | int port; |
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149 | char *err, *dummy_realhost; |
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150 | char host[128]; |
151 | int n, displaynum; |
152 | struct X11Private *pr; |
153 | |
154 | /* |
155 | * Split up display name into host and display-number parts. |
156 | */ |
157 | n = strcspn(display, ":"); |
158 | if (display[n]) |
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159 | displaynum = atoi(display + n + 1); |
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160 | else |
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161 | displaynum = 0; /* sensible default */ |
162 | if (n > sizeof(host) - 1) |
163 | n = sizeof(host) - 1; |
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164 | strncpy(host, display, n); |
165 | host[n] = '\0'; |
166 | |
167 | /* |
168 | * Try to find host. |
169 | */ |
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170 | addr = sk_namelookup(host, &dummy_realhost); |
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171 | if ((err = sk_addr_error(addr))) |
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172 | return err; |
173 | |
174 | port = 6000 + displaynum; |
175 | |
176 | /* |
177 | * Open socket. |
178 | */ |
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179 | pr = (struct X11Private *) smalloc(sizeof(struct X11Private)); |
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180 | pr->fn = &fn_table; |
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181 | pr->auth_protocol = NULL; |
182 | pr->verified = 0; |
183 | pr->data_read = 0; |
184 | pr->c = c; |
185 | |
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186 | pr->s = *s = sk_new(addr, port, 0, 1, (Plug) pr); |
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187 | if ((err = sk_socket_error(*s))) { |
188 | sfree(pr); |
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189 | return err; |
190 | } |
191 | |
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192 | sk_set_private_ptr(*s, pr); |
193 | sk_addr_free(addr); |
194 | return NULL; |
195 | } |
196 | |
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197 | void x11_close(Socket s) |
198 | { |
199 | struct X11Private *pr; |
200 | \rif (!s) |
201 | \rreturn; |
202 | \rpr = (struct X11Private *) sk_get_private_ptr(s); |
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203 | |
204 | if (pr->auth_protocol) { |
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205 | sfree(pr->auth_protocol); |
206 | sfree(pr->auth_data); |
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207 | } |
208 | |
209 | sfree(pr); |
210 | |
211 | sk_close(s); |
212 | } |
213 | |
214 | /* |
215 | * Called to send data down the raw connection. |
216 | */ |
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217 | void x11_send(Socket s, char *data, int len) |
218 | { |
219 | struct X11Private *pr = (struct X11Private *) sk_get_private_ptr(s); |
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220 | |
221 | if (s == NULL) |
222 | return; |
223 | |
224 | /* |
225 | * Read the first packet. |
226 | */ |
227 | while (len > 0 && pr->data_read < 12) |
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228 | pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++); |
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229 | if (pr->data_read < 12) |
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230 | return; |
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231 | |
232 | /* |
233 | * If we have not allocated the auth_protocol and auth_data |
234 | * strings, do so now. |
235 | */ |
236 | if (!pr->auth_protocol) { |
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237 | pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6); |
238 | pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8); |
239 | pr->auth_psize = (pr->auth_plen + 3) & ~3; |
240 | pr->auth_dsize = (pr->auth_dlen + 3) & ~3; |
241 | /* Leave room for a terminating zero, to make our lives easier. */ |
242 | pr->auth_protocol = (char *) smalloc(pr->auth_psize + 1); |
243 | pr->auth_data = (char *) smalloc(pr->auth_dsize); |
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244 | } |
245 | |
246 | /* |
247 | * Read the auth_protocol and auth_data strings. |
248 | */ |
249 | while (len > 0 && pr->data_read < 12 + pr->auth_psize) |
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250 | pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++); |
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251 | while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
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252 | pr->auth_data[pr->data_read++ - 12 - |
253 | pr->auth_psize] = (unsigned char) (len--, *data++); |
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254 | if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
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255 | return; |
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256 | |
257 | /* |
258 | * If we haven't verified the authentication, do so now. |
259 | */ |
260 | if (!pr->verified) { |
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261 | int ret; |
262 | |
263 | pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */ |
264 | ret = x11_verify(pr->auth_protocol, pr->auth_data, pr->auth_dlen); |
265 | |
266 | /* |
267 | * If authentication failed, construct and send an error |
268 | * packet, then terminate the connection. |
269 | */ |
270 | if (!ret) { |
271 | char message[] = "Authentication failed at PuTTY X11 proxy"; |
272 | unsigned char reply[8 + sizeof(message) + 4]; |
273 | int msglen = sizeof(message) - 1; /* skip zero byte */ |
274 | int msgsize = (msglen + 3) & ~3; |
275 | reply[0] = 0; /* failure */ |
276 | reply[1] = msglen; /* length of reason string */ |
277 | memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */ |
278 | PUT_16BIT(pr->firstpkt[0], reply + 6, msglen >> 2); /* data len */ |
279 | memset(reply + 8, 0, msgsize); |
280 | memcpy(reply + 8, message, msglen); |
281 | sshfwd_write(pr->c, reply, 8 + msgsize); |
282 | sshfwd_close(pr->c); |
283 | x11_close(s); |
284 | return; |
285 | } |
286 | |
287 | /* |
288 | * Now we know we're going to accept the connection. Strip |
289 | * the auth data. (TODO: if we ever work out how, we should |
290 | * replace some real auth data in here.) |
291 | */ |
292 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, 0); /* auth proto */ |
293 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, 0); /* auth data */ |
294 | sk_write(s, pr->firstpkt, 12); |
295 | pr->verified = 1; |
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296 | } |
297 | |
298 | /* |
299 | * After initialisation, just copy data simply. |
300 | */ |
301 | |
302 | sk_write(s, data, len); |
303 | } |