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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 | |
109 | if (!len) { |
110 | /* Connection has closed. */ |
111 | sshfwd_close(pr->c); |
112 | x11_close(s); |
113 | return 1; |
114 | } |
115 | sshfwd_write(pr->c, data, len); |
116 | return 1; |
117 | } |
118 | |
119 | /* |
120 | * Called to set up the raw connection. |
121 | * |
122 | * Returns an error message, or NULL on success. |
123 | * also, fills the SocketsStructure |
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124 | */ |
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125 | char *x11_init (Socket *s, char *display, void *c) { |
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126 | SockAddr addr; |
127 | int port; |
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128 | char *err, *dummy_realhost; |
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129 | char host[128]; |
130 | int n, displaynum; |
131 | struct X11Private *pr; |
132 | |
133 | /* |
134 | * Split up display name into host and display-number parts. |
135 | */ |
136 | n = strcspn(display, ":"); |
137 | if (display[n]) |
138 | displaynum = atoi(display+n+1); |
139 | else |
140 | displaynum = 0; /* sensible default */ |
141 | if (n > sizeof(host)-1) |
142 | n = sizeof(host)-1; |
143 | strncpy(host, display, n); |
144 | host[n] = '\0'; |
145 | |
146 | /* |
147 | * Try to find host. |
148 | */ |
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149 | addr = sk_namelookup(host, &dummy_realhost); |
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150 | if ( (err = sk_addr_error(addr)) ) |
151 | return err; |
152 | |
153 | port = 6000 + displaynum; |
154 | |
155 | /* |
156 | * Open socket. |
157 | */ |
158 | *s = sk_new(addr, port, 0, x11_receive); |
159 | if ( (err = sk_socket_error(*s)) ) |
160 | return err; |
161 | |
162 | pr = (struct X11Private *)smalloc(sizeof(struct X11Private)); |
163 | pr->auth_protocol = NULL; |
164 | pr->verified = 0; |
165 | pr->data_read = 0; |
166 | pr->c = c; |
167 | |
168 | sk_set_private_ptr(*s, pr); |
169 | sk_addr_free(addr); |
170 | return NULL; |
171 | } |
172 | |
173 | void x11_close (Socket s) { |
174 | struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s); |
175 | |
176 | if (pr->auth_protocol) { |
177 | sfree(pr->auth_protocol); |
178 | sfree(pr->auth_data); |
179 | } |
180 | |
181 | sfree(pr); |
182 | |
183 | sk_close(s); |
184 | } |
185 | |
186 | /* |
187 | * Called to send data down the raw connection. |
188 | */ |
189 | void x11_send (Socket s, char *data, int len) { |
190 | struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s); |
191 | |
192 | if (s == NULL) |
193 | return; |
194 | |
195 | /* |
196 | * Read the first packet. |
197 | */ |
198 | while (len > 0 && pr->data_read < 12) |
199 | pr->firstpkt[pr->data_read++] = (unsigned char)(len--, *data++); |
200 | if (pr->data_read < 12) |
201 | return; |
202 | |
203 | /* |
204 | * If we have not allocated the auth_protocol and auth_data |
205 | * strings, do so now. |
206 | */ |
207 | if (!pr->auth_protocol) { |
208 | pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+6); |
209 | pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+8); |
210 | pr->auth_psize = (pr->auth_plen + 3) &~ 3; |
211 | pr->auth_dsize = (pr->auth_dlen + 3) &~ 3; |
212 | /* Leave room for a terminating zero, to make our lives easier. */ |
213 | pr->auth_protocol = (char *)smalloc(pr->auth_psize+1); |
214 | pr->auth_data = (char *)smalloc(pr->auth_dsize); |
215 | } |
216 | |
217 | /* |
218 | * Read the auth_protocol and auth_data strings. |
219 | */ |
220 | while (len > 0 && pr->data_read < 12 + pr->auth_psize) |
221 | pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++); |
222 | while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
223 | pr->auth_data[pr->data_read++ - 12 - |
224 | pr->auth_psize] = (unsigned char)(len--, *data++); |
225 | if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
226 | return; |
227 | |
228 | /* |
229 | * If we haven't verified the authentication, do so now. |
230 | */ |
231 | if (!pr->verified) { |
232 | int ret; |
233 | |
234 | pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */ |
235 | ret = x11_verify(pr->auth_protocol, pr->auth_data, pr->auth_dlen); |
236 | |
237 | /* |
238 | * If authentication failed, construct and send an error |
239 | * packet, then terminate the connection. |
240 | */ |
241 | if (!ret) { |
242 | char message[] = "Authentication failed at PuTTY X11 proxy"; |
243 | unsigned char reply[8 + sizeof(message) + 4]; |
244 | int msglen = sizeof(message)-1; /* skip zero byte */ |
245 | int msgsize = (msglen+3) &~ 3; |
246 | reply[0] = 0; /* failure */ |
247 | reply[1] = msglen; /* length of reason string */ |
248 | memcpy(reply+2, pr->firstpkt+2, 4); /* major/minor proto vsn */ |
249 | PUT_16BIT(pr->firstpkt[0], reply+6, msglen >> 2); /* data len */ |
250 | memset(reply+8, 0, msgsize); |
251 | memcpy(reply+8, message, msglen); |
252 | sshfwd_write(pr->c, reply, 8+msgsize); |
253 | sshfwd_close(pr->c); |
254 | x11_close(s); |
255 | return; |
256 | } |
257 | |
258 | /* |
259 | * Now we know we're going to accept the connection. Strip |
260 | * the auth data. (TODO: if we ever work out how, we should |
261 | * replace some real auth data in here.) |
262 | */ |
263 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt+6, 0); /* auth proto */ |
264 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt+8, 0); /* auth data */ |
265 | sk_write(s, pr->firstpkt, 12); |
266 | pr->verified = 1; |
267 | } |
268 | |
269 | /* |
270 | * After initialisation, just copy data simply. |
271 | */ |
272 | |
273 | sk_write(s, data, len); |
274 | } |