| 1 | #include <windows.h> |
| 2 | #include <stdio.h> |
| 3 | #include <stdlib.h> |
| 4 | |
| 5 | #include "putty.h" |
| 6 | #include "ssh.h" |
| 7 | |
| 8 | #define GET_32BIT_LSB_FIRST(cp) \ |
| 9 | (((unsigned long)(unsigned char)(cp)[0]) | \ |
| 10 | ((unsigned long)(unsigned char)(cp)[1] << 8) | \ |
| 11 | ((unsigned long)(unsigned char)(cp)[2] << 16) | \ |
| 12 | ((unsigned long)(unsigned char)(cp)[3] << 24)) |
| 13 | |
| 14 | #define PUT_32BIT_LSB_FIRST(cp, value) ( \ |
| 15 | (cp)[0] = (value), \ |
| 16 | (cp)[1] = (value) >> 8, \ |
| 17 | (cp)[2] = (value) >> 16, \ |
| 18 | (cp)[3] = (value) >> 24 ) |
| 19 | |
| 20 | #define GET_16BIT_LSB_FIRST(cp) \ |
| 21 | (((unsigned long)(unsigned char)(cp)[0]) | \ |
| 22 | ((unsigned long)(unsigned char)(cp)[1] << 8)) |
| 23 | |
| 24 | #define PUT_16BIT_LSB_FIRST(cp, value) ( \ |
| 25 | (cp)[0] = (value), \ |
| 26 | (cp)[1] = (value) >> 8 ) |
| 27 | |
| 28 | #define GET_32BIT_MSB_FIRST(cp) \ |
| 29 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
| 30 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
| 31 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
| 32 | ((unsigned long)(unsigned char)(cp)[3])) |
| 33 | |
| 34 | #define PUT_32BIT_MSB_FIRST(cp, value) ( \ |
| 35 | (cp)[0] = (value) >> 24, \ |
| 36 | (cp)[1] = (value) >> 16, \ |
| 37 | (cp)[2] = (value) >> 8, \ |
| 38 | (cp)[3] = (value) ) |
| 39 | |
| 40 | #define GET_16BIT_MSB_FIRST(cp) \ |
| 41 | (((unsigned long)(unsigned char)(cp)[0] << 8) | \ |
| 42 | ((unsigned long)(unsigned char)(cp)[1])) |
| 43 | |
| 44 | #define PUT_16BIT_MSB_FIRST(cp, value) ( \ |
| 45 | (cp)[0] = (value) >> 8, \ |
| 46 | (cp)[1] = (value) ) |
| 47 | |
| 48 | #define GET_16BIT(endian, cp) \ |
| 49 | (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp)) |
| 50 | |
| 51 | #define PUT_16BIT(endian, cp, val) \ |
| 52 | (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val)) |
| 53 | |
| 54 | struct X11Private { |
| 55 | struct plug_function_table *fn; |
| 56 | /* the above variable absolutely *must* be the first in this structure */ |
| 57 | unsigned char firstpkt[12]; /* first X data packet */ |
| 58 | char *auth_protocol; |
| 59 | unsigned char *auth_data; |
| 60 | int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize; |
| 61 | int verified; |
| 62 | int throttled, throttle_override; |
| 63 | void *c; /* data used by ssh.c */ |
| 64 | Socket s; |
| 65 | }; |
| 66 | |
| 67 | void x11_close(Socket s); |
| 68 | |
| 69 | static unsigned char x11_authdata[64]; |
| 70 | static int x11_authdatalen; |
| 71 | |
| 72 | void x11_invent_auth(char *proto, int protomaxlen, |
| 73 | char *data, int datamaxlen) |
| 74 | { |
| 75 | char ourdata[64]; |
| 76 | int i; |
| 77 | |
| 78 | /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */ |
| 79 | x11_authdatalen = 16; |
| 80 | for (i = 0; i < 16; i++) |
| 81 | x11_authdata[i] = random_byte(); |
| 82 | |
| 83 | /* Now format for the recipient. */ |
| 84 | strncpy(proto, "MIT-MAGIC-COOKIE-1", protomaxlen); |
| 85 | ourdata[0] = '\0'; |
| 86 | for (i = 0; i < x11_authdatalen; i++) |
| 87 | sprintf(ourdata + strlen(ourdata), "%02x", x11_authdata[i]); |
| 88 | strncpy(data, ourdata, datamaxlen); |
| 89 | } |
| 90 | |
| 91 | static int x11_verify(char *proto, unsigned char *data, int dlen) |
| 92 | { |
| 93 | if (strcmp(proto, "MIT-MAGIC-COOKIE-1") != 0) |
| 94 | return 0; /* wrong protocol attempted */ |
| 95 | if (dlen != x11_authdatalen) |
| 96 | return 0; /* cookie was wrong length */ |
| 97 | if (memcmp(x11_authdata, data, dlen) != 0) |
| 98 | return 0; /* cookie was wrong cookie! */ |
| 99 | return 1; |
| 100 | } |
| 101 | |
| 102 | static int x11_closing(Plug plug, char *error_msg, int error_code, |
| 103 | int calling_back) |
| 104 | { |
| 105 | struct X11Private *pr = (struct X11Private *) plug; |
| 106 | |
| 107 | /* |
| 108 | * We have no way to communicate down the forwarded connection, |
| 109 | * so if an error occurred on the socket, we just ignore it |
| 110 | * and treat it like a proper close. |
| 111 | */ |
| 112 | sshfwd_close(pr->c); |
| 113 | x11_close(pr->s); |
| 114 | return 1; |
| 115 | } |
| 116 | |
| 117 | static int x11_receive(Plug plug, int urgent, char *data, int len) |
| 118 | { |
| 119 | struct X11Private *pr = (struct X11Private *) plug; |
| 120 | |
| 121 | if (sshfwd_write(pr->c, data, len) > 0) { |
| 122 | pr->throttled = 1; |
| 123 | sk_set_frozen(pr->s, 1); |
| 124 | } |
| 125 | |
| 126 | return 1; |
| 127 | } |
| 128 | |
| 129 | static void x11_sent(Plug plug, int bufsize) |
| 130 | { |
| 131 | struct X11Private *pr = (struct X11Private *) plug; |
| 132 | |
| 133 | sshfwd_unthrottle(pr->c, bufsize); |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Called to set up the raw connection. |
| 138 | * |
| 139 | * Returns an error message, or NULL on success. |
| 140 | * also, fills the SocketsStructure |
| 141 | */ |
| 142 | char *x11_init(Socket * s, char *display, void *c) |
| 143 | { |
| 144 | static struct plug_function_table fn_table = { |
| 145 | x11_closing, |
| 146 | x11_receive, |
| 147 | x11_sent, |
| 148 | NULL |
| 149 | }; |
| 150 | |
| 151 | SockAddr addr; |
| 152 | int port; |
| 153 | char *err, *dummy_realhost; |
| 154 | char host[128]; |
| 155 | int n, displaynum; |
| 156 | struct X11Private *pr; |
| 157 | |
| 158 | /* |
| 159 | * Split up display name into host and display-number parts. |
| 160 | */ |
| 161 | n = strcspn(display, ":"); |
| 162 | if (display[n]) |
| 163 | displaynum = atoi(display + n + 1); |
| 164 | else |
| 165 | displaynum = 0; /* sensible default */ |
| 166 | if (n > sizeof(host) - 1) |
| 167 | n = sizeof(host) - 1; |
| 168 | strncpy(host, display, n); |
| 169 | host[n] = '\0'; |
| 170 | |
| 171 | /* |
| 172 | * Try to find host. |
| 173 | */ |
| 174 | addr = sk_namelookup(host, &dummy_realhost); |
| 175 | if ((err = sk_addr_error(addr))) |
| 176 | return err; |
| 177 | |
| 178 | port = 6000 + displaynum; |
| 179 | |
| 180 | /* |
| 181 | * Open socket. |
| 182 | */ |
| 183 | pr = (struct X11Private *) smalloc(sizeof(struct X11Private)); |
| 184 | pr->fn = &fn_table; |
| 185 | pr->auth_protocol = NULL; |
| 186 | pr->verified = 0; |
| 187 | pr->data_read = 0; |
| 188 | pr->throttled = pr->throttle_override = 0; |
| 189 | pr->c = c; |
| 190 | |
| 191 | pr->s = *s = sk_new(addr, port, 0, 1, 0, (Plug) pr); |
| 192 | if ((err = sk_socket_error(*s))) { |
| 193 | sfree(pr); |
| 194 | return err; |
| 195 | } |
| 196 | |
| 197 | sk_set_private_ptr(*s, pr); |
| 198 | sk_addr_free(addr); |
| 199 | return NULL; |
| 200 | } |
| 201 | |
| 202 | void x11_close(Socket s) |
| 203 | { |
| 204 | struct X11Private *pr; |
| 205 | if (!s) |
| 206 | return; |
| 207 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 208 | if (pr->auth_protocol) { |
| 209 | sfree(pr->auth_protocol); |
| 210 | sfree(pr->auth_data); |
| 211 | } |
| 212 | |
| 213 | sfree(pr); |
| 214 | |
| 215 | sk_close(s); |
| 216 | } |
| 217 | |
| 218 | void x11_unthrottle(Socket s) |
| 219 | { |
| 220 | struct X11Private *pr; |
| 221 | if (!s) |
| 222 | return; |
| 223 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 224 | |
| 225 | pr->throttled = 0; |
| 226 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
| 227 | } |
| 228 | |
| 229 | void x11_override_throttle(Socket s, int enable) |
| 230 | { |
| 231 | struct X11Private *pr; |
| 232 | if (!s) |
| 233 | return; |
| 234 | pr = (struct X11Private *) sk_get_private_ptr(s); |
| 235 | |
| 236 | pr->throttle_override = enable; |
| 237 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
| 238 | } |
| 239 | |
| 240 | /* |
| 241 | * Called to send data down the raw connection. |
| 242 | */ |
| 243 | int x11_send(Socket s, char *data, int len) |
| 244 | { |
| 245 | struct X11Private *pr = (struct X11Private *) sk_get_private_ptr(s); |
| 246 | |
| 247 | if (s == NULL) |
| 248 | return 0; |
| 249 | |
| 250 | /* |
| 251 | * Read the first packet. |
| 252 | */ |
| 253 | while (len > 0 && pr->data_read < 12) |
| 254 | pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++); |
| 255 | if (pr->data_read < 12) |
| 256 | return 0; |
| 257 | |
| 258 | /* |
| 259 | * If we have not allocated the auth_protocol and auth_data |
| 260 | * strings, do so now. |
| 261 | */ |
| 262 | if (!pr->auth_protocol) { |
| 263 | pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6); |
| 264 | pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8); |
| 265 | pr->auth_psize = (pr->auth_plen + 3) & ~3; |
| 266 | pr->auth_dsize = (pr->auth_dlen + 3) & ~3; |
| 267 | /* Leave room for a terminating zero, to make our lives easier. */ |
| 268 | pr->auth_protocol = (char *) smalloc(pr->auth_psize + 1); |
| 269 | pr->auth_data = (char *) smalloc(pr->auth_dsize); |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Read the auth_protocol and auth_data strings. |
| 274 | */ |
| 275 | while (len > 0 && pr->data_read < 12 + pr->auth_psize) |
| 276 | pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++); |
| 277 | while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
| 278 | pr->auth_data[pr->data_read++ - 12 - |
| 279 | pr->auth_psize] = (unsigned char) (len--, *data++); |
| 280 | if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize) |
| 281 | return 0; |
| 282 | |
| 283 | /* |
| 284 | * If we haven't verified the authentication, do so now. |
| 285 | */ |
| 286 | if (!pr->verified) { |
| 287 | int ret; |
| 288 | |
| 289 | pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */ |
| 290 | ret = x11_verify(pr->auth_protocol, pr->auth_data, pr->auth_dlen); |
| 291 | |
| 292 | /* |
| 293 | * If authentication failed, construct and send an error |
| 294 | * packet, then terminate the connection. |
| 295 | */ |
| 296 | if (!ret) { |
| 297 | char message[] = "Authentication failed at PuTTY X11 proxy"; |
| 298 | unsigned char reply[8 + sizeof(message) + 4]; |
| 299 | int msglen = sizeof(message) - 1; /* skip zero byte */ |
| 300 | int msgsize = (msglen + 3) & ~3; |
| 301 | reply[0] = 0; /* failure */ |
| 302 | reply[1] = msglen; /* length of reason string */ |
| 303 | memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */ |
| 304 | PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */ |
| 305 | memset(reply + 8, 0, msgsize); |
| 306 | memcpy(reply + 8, message, msglen); |
| 307 | sshfwd_write(pr->c, reply, 8 + msgsize); |
| 308 | sshfwd_close(pr->c); |
| 309 | x11_close(s); |
| 310 | return 0; |
| 311 | } |
| 312 | |
| 313 | /* |
| 314 | * Now we know we're going to accept the connection. Strip |
| 315 | * the auth data. (TODO: if we ever work out how, we should |
| 316 | * replace some real auth data in here.) |
| 317 | */ |
| 318 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, 0); /* auth proto */ |
| 319 | PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, 0); /* auth data */ |
| 320 | sk_write(s, pr->firstpkt, 12); |
| 321 | pr->verified = 1; |
| 322 | } |
| 323 | |
| 324 | /* |
| 325 | * After initialisation, just copy data simply. |
| 326 | */ |
| 327 | |
| 328 | return sk_write(s, data, len); |
| 329 | } |