tinc-vpn.org Git - tinc/blob - src/proxy.c

   1 /*
   2     proxy.c -- Proxy handling functions.
   3     Copyright (C) 2015-2017 Guus Sliepen <guus@tinc-vpn.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21
  22 #include "connection.h"
  23 #include "logger.h"
  24 #include "meta.h"
  25 #include "netutl.h"
  26 #include "protocol.h"
  27 #include "proxy.h"
  28 #include "utils.h" //
  29
  30 proxytype_t proxytype;
  31 char *proxyhost;
  32 char *proxyport;
  33 char *proxyuser;
  34 char *proxypass;
  35
  36 static void update_address_ipv4(connection_t *c, void *address, void *port) {
  37         sockaddrfree(&c->address);
  38         memset(&c->address, 0, sizeof(c->address));
  39         c->address.sa.sa_family = AF_INET;
  40
  41         if(address) {
  42                 memcpy(&c->address.in.sin_addr, address, sizeof(ipv4_t));
  43         }
  44
  45         if(port) {
  46                 memcpy(&c->address.in.sin_port, port, sizeof(uint16_t));
  47         }
  48
  49         // OpenSSH -D returns all zero address, set it to 0.0.0.1 to prevent spamming ourselves.
  50         if(!memcmp(&c->address.in.sin_addr, "\0\0\0\0", 4)) {
  51                 memcpy(&c->address.in.sin_addr, "\0\0\0\01", 4);
  52         }
  53 }
  54
  55 static void update_address_ipv6(connection_t *c, void *address, void *port) {
  56         sockaddrfree(&c->address);
  57         memset(&c->address, 0, sizeof(c->address));
  58         c->address.sa.sa_family = AF_INET6;
  59
  60         if(address) {
  61                 memcpy(&c->address.in6.sin6_addr, address, sizeof(ipv6_t));
  62         }
  63
  64         if(port) {
  65                 memcpy(&c->address.in6.sin6_port, port, sizeof(uint16_t));
  66         }
  67
  68         // OpenSSH -D returns all zero address, set it to 0100:: to prevent spamming ourselves.
  69         if(!memcmp(&c->address.in6.sin6_addr, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16)) {
  70                 memcpy(&c->address.in6.sin6_addr, "\01\0\0\0\0\0\0\0", 8);
  71         }
  72 }
  73
  74 bool send_proxyrequest(connection_t *c) {
  75         switch(proxytype) {
  76         case PROXY_SOCKS4:
  77                 if(c->address.sa.sa_family != AF_INET) {
  78                         logger(LOG_ERR, "Can only connect to numeric IPv4 addresses through a SOCKS 4 proxy!");
  79                         return false;
  80                 }
  81
  82         case PROXY_SOCKS4A: {
  83                 if(c->address.sa.sa_family != AF_INET && c->address.sa.sa_family != AF_UNKNOWN) {
  84                         logger(LOG_ERR, "Can only connect to IPv4 addresses or hostnames through a SOCKS 4a proxy!");
  85                         return false;
  86                 }
  87
  88                 int len = 9;
  89
  90                 if(proxyuser) {
  91                         len += strlen(proxyuser);
  92                 }
  93
  94                 if(c->address.sa.sa_family == AF_UNKNOWN) {
  95                         len += 1 + strlen(c->address.unknown.address);
  96                 }
  97
  98                 char s4req[len];
  99                 s4req[0] = 4;
 100                 s4req[1] = 1;
 101
 102                 if(c->address.sa.sa_family == AF_INET) {
 103                         memcpy(s4req + 2, &c->address.in.sin_port, 2);
 104                         memcpy(s4req + 4, &c->address.in.sin_addr, 4);
 105                 } else {
 106                         uint16_t port = htons(atoi(c->address.unknown.port));
 107                         memcpy(s4req + 2, &port, 2);
 108                         memcpy(s4req + 4, "\0\0\0\1", 4);
 109                         strcpy(s4req + (9 + (proxyuser ? strlen(proxyuser) : 0)), c->address.unknown.address);
 110                 }
 111
 112                 if(proxyuser) {
 113                         strcpy(s4req + 8, proxyuser);
 114                 } else {
 115                         s4req[8] = 0;
 116                 }
 117
 118                 s4req[sizeof(s4req) - 1] = 0;
 119                 c->allow_request = PROXY;
 120                 return send_meta(c, s4req, sizeof(s4req));
 121         }
 122
 123         case PROXY_SOCKS5: {
 124                 int len = 3 + 6;
 125
 126                 if(c->address.sa.sa_family == AF_INET) {
 127                         len += 4;
 128                 } else if(c->address.sa.sa_family == AF_INET6) {
 129                         len += 16;
 130                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 131                         len += 1 + strlen(c->address.unknown.address);
 132                 } else {
 133                         logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
 134                         return false;
 135                 }
 136
 137                 if(proxypass) {
 138                         len += 3 + strlen(proxyuser) + strlen(proxypass);
 139                 }
 140
 141                 char s5req[len];
 142                 int i = 0;
 143                 s5req[i++] = 5;
 144                 s5req[i++] = 1;
 145
 146                 if(proxypass) {
 147                         s5req[i++] = 2;
 148                         s5req[i++] = 1;
 149                         s5req[i++] = strlen(proxyuser);
 150                         strcpy(s5req + i, proxyuser);
 151                         i += strlen(proxyuser);
 152                         s5req[i++] = strlen(proxypass);
 153                         strcpy(s5req + i, proxypass);
 154                         i += strlen(proxypass);
 155                 } else {
 156                         s5req[i++] = 0;
 157                 }
 158
 159                 s5req[i++] = 5;
 160                 s5req[i++] = 1;
 161                 s5req[i++] = 0;
 162
 163                 if(c->address.sa.sa_family == AF_INET) {
 164                         s5req[i++] = 1;
 165                         memcpy(s5req + i, &c->address.in.sin_addr, 4);
 166                         i += 4;
 167                         memcpy(s5req + i, &c->address.in.sin_port, 2);
 168                         i += 2;
 169                 } else if(c->address.sa.sa_family == AF_INET6) {
 170                         s5req[i++] = 4;
 171                         memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
 172                         i += 16;
 173                         memcpy(s5req + i, &c->address.in6.sin6_port, 2);
 174                         i += 2;
 175                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 176                         s5req[i++] = 3;
 177                         int len = strlen(c->address.unknown.address);
 178                         s5req[i++] = len;
 179                         memcpy(s5req + i, c->address.unknown.address, len);
 180                         i += len;
 181                         uint16_t port = htons(atoi(c->address.unknown.port));
 182                         memcpy(s5req + i, &port, 2);
 183                         i += 2;
 184                 } else {
 185                         logger(LOG_ERR, "Unknown address family while trying to connect to SOCKS5 proxy");
 186                         return false;
 187                 }
 188
 189                 if(i > len) {
 190                         abort();
 191                 }
 192
 193                 c->allow_request = PROXY;
 194                 return send_meta(c, s5req, sizeof(s5req));
 195         }
 196
 197         case PROXY_HTTP: {
 198                 char *host;
 199                 char *port;
 200
 201                 sockaddr2str(&c->address, &host, &port);
 202                 send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
 203                 free(host);
 204                 free(port);
 205                 c->allow_request = PROXY;
 206                 return true;
 207         }
 208
 209         case PROXY_EXEC:
 210                 abort();
 211
 212         default:
 213                 logger(LOG_ERR, "Unknown proxy type");
 214                 return false;
 215         }
 216 }
 217
 218 int receive_proxy_meta(connection_t *c, int start, int lenin) {
 219         switch(proxytype) {
 220         case PROXY_SOCKS4:
 221         case PROXY_SOCKS4A:
 222                 if(c->buflen < 8) {
 223                         return 0;
 224                 }
 225
 226                 if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
 227                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 228                                 update_address_ipv4(c, c->buffer + 4, c->buffer + 2);
 229                         }
 230
 231                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 232                         c->allow_request = ID;
 233                         c->status.proxy_passed = true;
 234                         send_id(c);
 235                         return 8;
 236                 } else {
 237                         logger(LOG_ERR, "Proxy request rejected");
 238                         return -1;
 239                 }
 240
 241         case PROXY_SOCKS5:
 242                 if(c->buflen < 2) {
 243                         return 0;
 244                 }
 245
 246                 if(c->buffer[0] != 0x05 || c->buffer[1] == (char)0xff) {
 247                         logger(LOG_ERR, "Proxy authentication method rejected");
 248                         return -1;
 249                 }
 250
 251                 int offset = 2;
 252
 253                 if(c->buffer[1] == 0x02) {
 254                         if(c->buflen < 4) {
 255                                 return 0;
 256                         }
 257
 258                         if(c->buffer[2] != 0x05 || c->buffer[3] != 0x00) {
 259                                 logger(LOG_ERR, "Proxy username/password rejected");
 260                                 return -1;
 261                         }
 262
 263                         offset += 2;
 264                 }
 265
 266                 if(c->buflen - offset < 7) {
 267                         return 0;
 268                 }
 269
 270                 if(c->buffer[offset] != 0x05  || c->buffer[offset + 1] != 0x00) {
 271                         logger(LOG_ERR, "Proxy request rejected");
 272                         return -1;
 273                 }
 274
 275                 int replen = offset + 6;
 276
 277                 switch(c->buffer[offset + 3]) {
 278                 case 0x01: // IPv4
 279                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 280                                 update_address_ipv4(c, c->buffer + offset + 4, c->buffer + offset + 8);
 281                         }
 282
 283                         replen += 4;
 284                         break;
 285
 286                 case 0x03: // Hostname
 287                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 288                                 update_address_ipv4(c, "\0\0\0\1", "\0\0");
 289                         }
 290
 291                         replen += ((uint8_t *)c->buffer)[offset + 4];
 292                         break;
 293
 294                 case 0x04: // IPv6
 295                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 296                                 update_address_ipv6(c, c->buffer + offset + 4, c->buffer + offset + 20);
 297                         }
 298
 299                         replen += 16;
 300                         break;
 301
 302                 default:
 303                         logger(LOG_ERR, "Proxy reply malformed");
 304                         return -1;
 305                 }
 306
 307                 if(c->buflen < replen) {
 308                         return 0;
 309                 } else {
 310                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 311                         c->allow_request = ID;
 312                         c->status.proxy_passed = true;
 313                         send_id(c);
 314                         return replen;
 315                 }
 316
 317         case PROXY_HTTP: {
 318                 char *p = memchr(c->buffer, '\n', c->buflen);
 319
 320                 if(!p || p - c->buffer >= c->buflen) {
 321                         return 0;
 322                 }
 323
 324                 while((p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer)))) {
 325                         if(p > c->buffer + 3 && !memcmp(p - 3, "\r\n\r\n", 4)) {
 326                                 break;
 327                         }
 328                 }
 329
 330                 if(!p) {
 331                         return 0;
 332                 }
 333
 334                 if(c->buflen < 9) {
 335                         return 0;
 336                 }
 337
 338                 if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
 339                         if(!strncmp(c->buffer + 9, "200", 3)) {
 340                                 if(c->address.sa.sa_family == AF_UNKNOWN) {
 341                                         update_address_ipv4(c, "\0\0\0\1", "\0\0");
 342                                 }
 343
 344                                 logger(LOG_DEBUG, "Proxy request granted");
 345                                 replen = p  + 1 - c->buffer;
 346                                 c->allow_request = ID;
 347                                 c->status.proxy_passed = true;
 348                                 send_id(c);
 349                                 return replen;
 350                         } else {
 351                                 p = memchr(c->buffer, '\n', c->buflen);
 352                                 p[-1] = 0;
 353                                 logger(LOG_ERR, "Proxy request rejected: %s", c->buffer + 9);
 354                                 return false;
 355                         }
 356                 } else {
 357                         logger(LOG_ERR, "Proxy reply malformed");
 358                         return -1;
 359                 }
 360         }
 361
 362         default:
 363                 abort();
 364         }
 365 }