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         // fallthrough
  83         case PROXY_SOCKS4A: {
  84                 if(c->address.sa.sa_family != AF_INET && c->address.sa.sa_family != AF_UNKNOWN) {
  85                         logger(LOG_ERR, "Can only connect to IPv4 addresses or hostnames through a SOCKS 4a proxy!");
  86                         return false;
  87                 }
  88
  89                 int len = 9;
  90
  91                 if(proxyuser) {
  92                         len += strlen(proxyuser);
  93                 }
  94
  95                 if(c->address.sa.sa_family == AF_UNKNOWN) {
  96                         len += 1 + strlen(c->address.unknown.address);
  97                 }
  98
  99                 char s4req[len];
 100                 s4req[0] = 4;
 101                 s4req[1] = 1;
 102
 103                 if(c->address.sa.sa_family == AF_INET) {
 104                         memcpy(s4req + 2, &c->address.in.sin_port, 2);
 105                         memcpy(s4req + 4, &c->address.in.sin_addr, 4);
 106                 } else {
 107                         uint16_t port = htons(atoi(c->address.unknown.port));
 108                         memcpy(s4req + 2, &port, 2);
 109                         memcpy(s4req + 4, "\0\0\0\1", 4);
 110                         strcpy(s4req + (9 + (proxyuser ? strlen(proxyuser) : 0)), c->address.unknown.address);
 111                 }
 112
 113                 if(proxyuser) {
 114                         strcpy(s4req + 8, proxyuser);
 115                 } else {
 116                         s4req[8] = 0;
 117                 }
 118
 119                 s4req[sizeof(s4req) - 1] = 0;
 120                 c->allow_request = PROXY;
 121                 return send_meta(c, s4req, sizeof(s4req));
 122         }
 123
 124         case PROXY_SOCKS5: {
 125                 int len = 3 + 6;
 126
 127                 if(c->address.sa.sa_family == AF_INET) {
 128                         len += 4;
 129                 } else if(c->address.sa.sa_family == AF_INET6) {
 130                         len += 16;
 131                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 132                         len += 1 + strlen(c->address.unknown.address);
 133                 } else {
 134                         logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
 135                         return false;
 136                 }
 137
 138                 if(proxypass) {
 139                         len += 3 + strlen(proxyuser) + strlen(proxypass);
 140                 }
 141
 142                 char s5req[len];
 143                 int i = 0;
 144                 s5req[i++] = 5;
 145                 s5req[i++] = 1;
 146
 147                 if(proxypass) {
 148                         s5req[i++] = 2;
 149                         s5req[i++] = 1;
 150                         s5req[i++] = strlen(proxyuser);
 151                         strcpy(s5req + i, proxyuser);
 152                         i += strlen(proxyuser);
 153                         s5req[i++] = strlen(proxypass);
 154                         strcpy(s5req + i, proxypass);
 155                         i += strlen(proxypass);
 156                 } else {
 157                         s5req[i++] = 0;
 158                 }
 159
 160                 s5req[i++] = 5;
 161                 s5req[i++] = 1;
 162                 s5req[i++] = 0;
 163
 164                 if(c->address.sa.sa_family == AF_INET) {
 165                         s5req[i++] = 1;
 166                         memcpy(s5req + i, &c->address.in.sin_addr, 4);
 167                         i += 4;
 168                         memcpy(s5req + i, &c->address.in.sin_port, 2);
 169                         i += 2;
 170                 } else if(c->address.sa.sa_family == AF_INET6) {
 171                         s5req[i++] = 4;
 172                         memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
 173                         i += 16;
 174                         memcpy(s5req + i, &c->address.in6.sin6_port, 2);
 175                         i += 2;
 176                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 177                         s5req[i++] = 3;
 178                         int len = strlen(c->address.unknown.address);
 179                         s5req[i++] = len;
 180                         memcpy(s5req + i, c->address.unknown.address, len);
 181                         i += len;
 182                         uint16_t port = htons(atoi(c->address.unknown.port));
 183                         memcpy(s5req + i, &port, 2);
 184                         i += 2;
 185                 } else {
 186                         logger(LOG_ERR, "Unknown address family while trying to connect to SOCKS5 proxy");
 187                         return false;
 188                 }
 189
 190                 if(i > len) {
 191                         abort();
 192                 }
 193
 194                 c->allow_request = PROXY;
 195                 return send_meta(c, s5req, sizeof(s5req));
 196         }
 197
 198         case PROXY_HTTP: {
 199                 char *host;
 200                 char *port;
 201
 202                 sockaddr2str(&c->address, &host, &port);
 203                 send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
 204                 free(host);
 205                 free(port);
 206                 c->allow_request = PROXY;
 207                 return true;
 208         }
 209
 210         case PROXY_EXEC:
 211                 abort();
 212
 213         default:
 214                 logger(LOG_ERR, "Unknown proxy type");
 215                 return false;
 216         }
 217 }
 218
 219 int receive_proxy_meta(connection_t *c) {
 220         switch(proxytype) {
 221         case PROXY_SOCKS4:
 222         case PROXY_SOCKS4A:
 223                 if(c->buflen < 8) {
 224                         return 0;
 225                 }
 226
 227                 if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
 228                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 229                                 update_address_ipv4(c, c->buffer + 4, c->buffer + 2);
 230                         }
 231
 232                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 233                         c->allow_request = ID;
 234                         c->status.proxy_passed = true;
 235                         send_id(c);
 236                         return 8;
 237                 } else {
 238                         logger(LOG_ERR, "Proxy request rejected");
 239                         return -1;
 240                 }
 241
 242         case PROXY_SOCKS5:
 243                 if(c->buflen < 2) {
 244                         return 0;
 245                 }
 246
 247                 if(c->buffer[0] != 0x05 || c->buffer[1] == (char)0xff) {
 248                         logger(LOG_ERR, "Proxy authentication method rejected");
 249                         return -1;
 250                 }
 251
 252                 int offset = 2;
 253
 254                 if(c->buffer[1] == 0x02) {
 255                         if(c->buflen < 4) {
 256                                 return 0;
 257                         }
 258
 259                         if(c->buffer[2] != 0x05 || c->buffer[3] != 0x00) {
 260                                 logger(LOG_ERR, "Proxy username/password rejected");
 261                                 return -1;
 262                         }
 263
 264                         offset += 2;
 265                 }
 266
 267                 if(c->buflen - offset < 7) {
 268                         return 0;
 269                 }
 270
 271                 if(c->buffer[offset] != 0x05  || c->buffer[offset + 1] != 0x00) {
 272                         logger(LOG_ERR, "Proxy request rejected");
 273                         return -1;
 274                 }
 275
 276                 int replen = offset + 6;
 277
 278                 switch(c->buffer[offset + 3]) {
 279                 case 0x01: // IPv4
 280                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 281                                 update_address_ipv4(c, c->buffer + offset + 4, c->buffer + offset + 8);
 282                         }
 283
 284                         replen += 4;
 285                         break;
 286
 287                 case 0x03: // Hostname
 288                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 289                                 update_address_ipv4(c, "\0\0\0\1", "\0\0");
 290                         }
 291
 292                         replen += ((uint8_t *)c->buffer)[offset + 4];
 293                         break;
 294
 295                 case 0x04: // IPv6
 296                         if(c->address.sa.sa_family == AF_UNKNOWN) {
 297                                 update_address_ipv6(c, c->buffer + offset + 4, c->buffer + offset + 20);
 298                         }
 299
 300                         replen += 16;
 301                         break;
 302
 303                 default:
 304                         logger(LOG_ERR, "Proxy reply malformed");
 305                         return -1;
 306                 }
 307
 308                 if(c->buflen < replen) {
 309                         return 0;
 310                 } else {
 311                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 312                         c->allow_request = ID;
 313                         c->status.proxy_passed = true;
 314                         send_id(c);
 315                         return replen;
 316                 }
 317
 318         case PROXY_HTTP: {
 319                 char *p = memchr(c->buffer, '\n', c->buflen);
 320
 321                 if(!p || p - c->buffer >= c->buflen) {
 322                         return 0;
 323                 }
 324
 325                 while((p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer)))) {
 326                         if(p > c->buffer + 3 && !memcmp(p - 3, "\r\n\r\n", 4)) {
 327                                 break;
 328                         }
 329                 }
 330
 331                 if(!p) {
 332                         return 0;
 333                 }
 334
 335                 if(c->buflen < 9) {
 336                         return 0;
 337                 }
 338
 339                 if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
 340                         if(!strncmp(c->buffer + 9, "200", 3)) {
 341                                 if(c->address.sa.sa_family == AF_UNKNOWN) {
 342                                         update_address_ipv4(c, "\0\0\0\1", "\0\0");
 343                                 }
 344
 345                                 logger(LOG_DEBUG, "Proxy request granted");
 346                                 replen = p  + 1 - c->buffer;
 347                                 c->allow_request = ID;
 348                                 c->status.proxy_passed = true;
 349                                 send_id(c);
 350                                 return replen;
 351                         } else {
 352                                 p = memchr(c->buffer, '\n', c->buflen);
 353                                 p[-1] = 0;
 354                                 logger(LOG_ERR, "Proxy request rejected: %s", c->buffer + 9);
 355                                 return false;
 356                         }
 357                 } else {
 358                         logger(LOG_ERR, "Proxy reply malformed");
 359                         return -1;
 360                 }
 361         }
 362
 363         default:
 364                 abort();
 365         }
 366 }