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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 { |
65 | unsigned char firstpkt[12]; /* first X data packet */ |
66 | char *auth_protocol; |
67 | unsigned char *auth_data; |
68 | int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize; |
69 | int verified; |
70 | void *c; /* data used by ssh.c */ |
71 | }; |
72 | |
73 | void x11_close (Socket s); |
74 | |
75 | static unsigned char x11_authdata[64]; |
76 | static int x11_authdatalen; |
77 | |
78 | void x11_invent_auth(char *proto, int protomaxlen, |
79 | char *data, int datamaxlen) { |
80 | char ourdata[64]; |
81 | int i; |
82 | |
83 | /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */ |
84 | x11_authdatalen = 16; |
85 | for (i = 0; i < 16; i++) |
86 | x11_authdata[i] = random_byte(); |
87 | |
88 | /* Now format for the recipient. */ |
89 | strncpy(proto, "MIT-MAGIC-COOKIE-1", protomaxlen); |
90 | ourdata[0] = '\0'; |
91 | for (i = 0; i < x11_authdatalen; i++) |
92 | sprintf(ourdata+strlen(ourdata), "%02x", x11_authdata[i]); |
93 | strncpy(data, ourdata, datamaxlen); |
94 | } |
95 | |
96 | static int x11_verify(char *proto, unsigned char *data, int dlen) { |
97 | if (strcmp(proto, "MIT-MAGIC-COOKIE-1") != 0) |
98 | return 0; /* wrong protocol attempted */ |
99 | if (dlen != x11_authdatalen) |
100 | return 0; /* cookie was wrong length */ |
101 | if (memcmp(x11_authdata, data, dlen) != 0) |
102 | return 0; /* cookie was wrong cookie! */ |
103 | return 1; |
104 | } |
105 | |
106 | static int x11_receive (Socket s, int urgent, char *data, int len) { |
107 | struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s); |
108 | |
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109 | if (urgent==3) { |
110 | /* |
111 | * A socket error has occurred. We have no way to |
112 | * communicate this down the forwarded connection, so we'll |
113 | * just treat it like a proper close. |
114 | */ |
115 | len = 0; |
116 | } |
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117 | if (!len) { |
118 | /* Connection has closed. */ |
119 | sshfwd_close(pr->c); |
120 | x11_close(s); |
121 | return 1; |
122 | } |
123 | sshfwd_write(pr->c, data, len); |
124 | return 1; |
125 | } |
126 | |
127 | /* |
128 | * Called to set up the raw connection. |
129 | * |
130 | * Returns an error message, or NULL on success. |
131 | * also, fills the SocketsStructure |
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132 | */ |
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133 | char *x11_init (Socket *s, char *display, void *c) { |
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134 | SockAddr addr; |
135 | int port; |
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136 | char *err, *dummy_realhost; |
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137 | char host[128]; |
138 | int n, displaynum; |
139 | struct X11Private *pr; |
140 | |
141 | /* |
142 | * Split up display name into host and display-number parts. |
143 | */ |
144 | n = strcspn(display, ":"); |
145 | if (display[n]) |
146 | displaynum = atoi(display+n+1); |
147 | else |
148 | displaynum = 0; /* sensible default */ |
149 | if (n > sizeof(host)-1) |
150 | n = sizeof(host)-1; |
151 | strncpy(host, display, n); |
152 | host[n] = '\0'; |
153 | |
154 | /* |
155 | * Try to find host. |
156 | */ |
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157 | addr = sk_namelookup(host, &dummy_realhost); |
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158 | if ( (err = sk_addr_error(addr)) ) |
159 | return err; |
160 | |
161 | port = 6000 + displaynum; |
162 | |
163 | /* |
164 | * Open socket. |
165 | */ |
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166 | *s = sk_new(addr, port, 0, 1, x11_receive); |
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167 | if ( (err = sk_socket_error(*s)) ) |
168 | return err; |
169 | |
170 | pr = (struct X11Private *)smalloc(sizeof(struct X11Private)); |
171 | pr->auth_protocol = NULL; |
172 | pr->verified = 0; |
173 | pr->data_read = 0; |
174 | pr->c = c; |
175 | |
176 | sk_set_private_ptr(*s, pr); |
177 | sk_addr_free(addr); |
178 | return NULL; |
179 | } |
180 | |
181 | void x11_close (Socket s) { |
182 | struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s); |
183 | |
184 | if (pr->auth_protocol) { |
185 | sfree(pr->auth_protocol); |
186 | sfree(pr->auth_data); |
187 | } |
188 | |
189 | sfree(pr); |
190 | |
191 | sk_close(s); |
192 | } |
193 | |
194 | /* |
195 | * Called to send data down the raw connection. |
196 | */ |
197 | void x11_send (Socket s, char *data, int len) { |
198 | struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s); |
199 | |
200 | if (s == NULL) |
201 | return; |
202 | |
203 | /* |
204 | * Read the first packet. |
205 | */ |
206 | while (len > 0 && pr->data_read < 12) |
207 | pr->firstpkt[pr->data_read++] = (unsigned char)(len--, *data++); |
208 | if (pr->data_read < 12) |
209 | return; |
210 | |
211 | /* |
212 | * If we have not allocated the auth_protocol and auth_data |
213 | * strings, do so now. |
214 | */ |
215 | if (!pr->auth_protocol) { |
216 | pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+6); |
217 | pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+8); |
218 | pr->auth_psize = (pr->auth_plen + 3) &~ 3; |
219 | pr->auth_dsize = (pr->auth_dlen + 3) &~ 3; |
220 | /* Leave room for a terminating zero, to make our lives easier. */ |
221 | pr->auth_protocol = (char *)smalloc(pr->auth_psize+1); |
222 | pr->auth_data = (char *)smalloc(pr->auth_dsize); |
223 | } |
224 | |
225 | /* |
226 | * Read the auth_protocol and auth_data strings. |
227 | */ |
228 | while (len > 0 && pr->data_read < 12 + pr->auth_psize) |
229 | pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++); |
230 | while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
231 | pr->auth_data[pr->data_read++ - 12 - |
232 | pr->auth_psize] = (unsigned char)(len--, *data++); |
233 | if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
234 | return; |
235 | |
236 | /* |
237 | * If we haven't verified the authentication, do so now. |
238 | */ |
239 | if (!pr->verified) { |
240 | int ret; |
241 | |
242 | pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */ |
243 | ret = x11_verify(pr->auth_protocol, pr->auth_data, pr->auth_dlen); |
244 | |
245 | /* |
246 | * If authentication failed, construct and send an error |
247 | * packet, then terminate the connection. |
248 | */ |
249 | if (!ret) { |
250 | char message[] = "Authentication failed at PuTTY X11 proxy"; |
251 | unsigned char reply[8 + sizeof(message) + 4]; |
252 | int msglen = sizeof(message)-1; /* skip zero byte */ |
253 | int msgsize = (msglen+3) &~ 3; |
254 | reply[0] = 0; /* failure */ |
255 | reply[1] = msglen; /* length of reason string */ |
256 | memcpy(reply+2, pr->firstpkt+2, 4); /* major/minor proto vsn */ |
257 | PUT_16BIT(pr->firstpkt[0], reply+6, msglen >> 2); /* data len */ |
258 | memset(reply+8, 0, msgsize); |
259 | memcpy(reply+8, message, msglen); |
260 | sshfwd_write(pr->c, reply, 8+msgsize); |
261 | sshfwd_close(pr->c); |
262 | x11_close(s); |
263 | return; |
264 | } |
265 | |
266 | /* |
267 | * Now we know we're going to accept the connection. Strip |
268 | * the auth data. (TODO: if we ever work out how, we should |
269 | * replace some real auth data in here.) |
270 | */ |
271 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt+6, 0); /* auth proto */ |
272 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt+8, 0); /* auth data */ |
273 | sk_write(s, pr->firstpkt, 12); |
274 | pr->verified = 1; |
275 | } |
276 | |
277 | /* |
278 | * After initialisation, just copy data simply. |
279 | */ |
280 | |
281 | sk_write(s, data, len); |
282 | } |