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         if(address)
  41                 memcpy(&c->address.in.sin_addr, address, sizeof(ipv4_t));
  42         if(port)
  43                 memcpy(&c->address.in.sin_port, port, sizeof(uint16_t));
  44         // OpenSSH -D returns all zero address, set it to 0.0.0.1 to prevent spamming ourselves.
  45         if(!memcmp(&c->address.in.sin_addr, "\0\0\0\0", 4))
  46                 memcpy(&c->address.in.sin_addr, "\0\0\0\01", 4);
  47 }
  48
  49 static void update_address_ipv6(connection_t *c, void *address, void *port) {
  50         sockaddrfree(&c->address);
  51         memset(&c->address, 0, sizeof c->address);
  52         c->address.sa.sa_family = AF_INET6;
  53         if(address)
  54                 memcpy(&c->address.in6.sin6_addr, address, sizeof(ipv6_t));
  55         if(port)
  56                 memcpy(&c->address.in6.sin6_port, port, sizeof(uint16_t));
  57         // OpenSSH -D returns all zero address, set it to 0100:: to prevent spamming ourselves.
  58         if(!memcmp(&c->address.in6.sin6_addr, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16))
  59                 memcpy(&c->address.in6.sin6_addr, "\01\0\0\0\0\0\0\0", 8);
  60 }
  61
  62 bool send_proxyrequest(connection_t *c) {
  63         switch(proxytype) {
  64         case PROXY_SOCKS4:
  65                 if(c->address.sa.sa_family != AF_INET) {
  66                         logger(LOG_ERR, "Can only connect to numeric IPv4 addresses through a SOCKS 4 proxy!");
  67                         return false;
  68                 }
  69         case PROXY_SOCKS4A: {
  70                 if(c->address.sa.sa_family != AF_INET && c->address.sa.sa_family != AF_UNKNOWN) {
  71                         logger(LOG_ERR, "Can only connect to IPv4 addresses or hostnames through a SOCKS 4a proxy!");
  72                         return false;
  73                 }
  74                 int len = 9;
  75                 if(proxyuser)
  76                         len += strlen(proxyuser);
  77                 if(c->address.sa.sa_family == AF_UNKNOWN)
  78                         len += 1 + strlen(c->address.unknown.address);
  79                 char s4req[len];
  80                 s4req[0] = 4;
  81                 s4req[1] = 1;
  82                 if(c->address.sa.sa_family == AF_INET) {
  83                         memcpy(s4req + 2, &c->address.in.sin_port, 2);
  84                         memcpy(s4req + 4, &c->address.in.sin_addr, 4);
  85                 } else {
  86                         uint16_t port = htons(atoi(c->address.unknown.port));
  87                         memcpy(s4req + 2, &port, 2);
  88                         memcpy(s4req + 4, "\0\0\0\1", 4);
  89                         strcpy(s4req + (9 + (proxyuser ? strlen(proxyuser) : 0)), c->address.unknown.address);
  90                 }
  91                 if(proxyuser)
  92                         strcpy(s4req + 8, proxyuser);
  93                 else
  94                         s4req[8] = 0;
  95                 s4req[sizeof s4req - 1] = 0;
  96                 c->allow_request = PROXY;
  97                 return send_meta(c, s4req, sizeof s4req);
  98         }
  99
 100         case PROXY_SOCKS5: {
 101                 int len = 3 + 6;
 102                 if(c->address.sa.sa_family == AF_INET) {
 103                         len += 4;
 104                 } else if(c->address.sa.sa_family == AF_INET6) {
 105                         len += 16;
 106                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 107                         len += 1 + strlen(c->address.unknown.address);
 108                 } else {
 109                         logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
 110                         return false;
 111                 }
 112                 if(proxypass)
 113                         len += 3 + strlen(proxyuser) + strlen(proxypass);
 114                 char s5req[len];
 115                 int i = 0;
 116                 s5req[i++] = 5;
 117                 s5req[i++] = 1;
 118                 if(proxypass) {
 119                         s5req[i++] = 2;
 120                         s5req[i++] = 1;
 121                         s5req[i++] = strlen(proxyuser);
 122                         strcpy(s5req + i, proxyuser);
 123                         i += strlen(proxyuser);
 124                         s5req[i++] = strlen(proxypass);
 125                         strcpy(s5req + i, proxypass);
 126                         i += strlen(proxypass);
 127                 } else {
 128                         s5req[i++] = 0;
 129                 }
 130                 s5req[i++] = 5;
 131                 s5req[i++] = 1;
 132                 s5req[i++] = 0;
 133                 if(c->address.sa.sa_family == AF_INET) {
 134                         s5req[i++] = 1;
 135                         memcpy(s5req + i, &c->address.in.sin_addr, 4);
 136                         i += 4;
 137                         memcpy(s5req + i, &c->address.in.sin_port, 2);
 138                         i += 2;
 139                 } else if(c->address.sa.sa_family == AF_INET6) {
 140                         s5req[i++] = 4;
 141                         memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
 142                         i += 16;
 143                         memcpy(s5req + i, &c->address.in6.sin6_port, 2);
 144                         i += 2;
 145                 } else if(c->address.sa.sa_family == AF_UNKNOWN) {
 146                         s5req[i++] = 3;
 147                         int len = strlen(c->address.unknown.address);
 148                         s5req[i++] = len;
 149                         memcpy(s5req + i, c->address.unknown.address, len);
 150                         i += len;
 151                         uint16_t port = htons(atoi(c->address.unknown.port));
 152                         memcpy(s5req + i, &port, 2);
 153                         i += 2;
 154                 } else {
 155                         logger(LOG_ERR, "Unknown address family while trying to connect to SOCKS5 proxy");
 156                         return false;
 157                 }
 158                 if(i > len)
 159                         abort();
 160                 c->allow_request = PROXY;
 161                 return send_meta(c, s5req, sizeof s5req);
 162         }
 163
 164         case PROXY_HTTP: {
 165                 char *host;
 166                 char *port;
 167
 168                 sockaddr2str(&c->address, &host, &port);
 169                 send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
 170                 free(host);
 171                 free(port);
 172                 c->allow_request = PROXY;
 173                 return true;
 174         }
 175
 176         case PROXY_EXEC:
 177                 abort();
 178
 179         default:
 180                 logger(LOG_ERR, "Unknown proxy type");
 181                 return false;
 182         }
 183 }
 184
 185 int receive_proxy_meta(connection_t *c, int start, int lenin) {
 186         switch(proxytype) {
 187         case PROXY_SOCKS4:
 188         case PROXY_SOCKS4A:
 189                 if(c->buflen < 8)
 190                         return 0;
 191                 if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
 192                         if(c->address.sa.sa_family == AF_UNKNOWN)
 193                                 update_address_ipv4(c, c->buffer + 4, c->buffer + 2);
 194
 195                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 196                         c->allow_request = ID;
 197                         c->status.proxy_passed = true;
 198                         send_id(c);
 199                         return 8;
 200                 } else {
 201                         logger(LOG_ERR, "Proxy request rejected");
 202                         return -1;
 203                 }
 204
 205         case PROXY_SOCKS5:
 206                 if(c->buflen < 2)
 207                         return 0;
 208                 if(c->buffer[0] != 0x05 || c->buffer[1] == (char)0xff) {
 209                         logger(LOG_ERR, "Proxy authentication method rejected");
 210                         return -1;
 211                 }
 212                 int offset = 2;
 213                 if(c->buffer[1] == 0x02) {
 214                         if(c->buflen < 4)
 215                                 return 0;
 216                         if(c->buffer[2] != 0x05 || c->buffer[3] != 0x00) {
 217                                 logger(LOG_ERR, "Proxy username/password rejected");
 218                                 return -1;
 219                         }
 220                         offset += 2;
 221                 }
 222                 if(c->buflen - offset < 7)
 223                         return 0;
 224                 if(c->buffer[offset] != 0x05  || c->buffer[offset + 1] != 0x00) {
 225                         logger(LOG_ERR, "Proxy request rejected");
 226                         return -1;
 227                 }
 228                 int replen = offset + 6;
 229                 switch(c->buffer[offset + 3]) {
 230                         case 0x01: // IPv4
 231                                 if(c->address.sa.sa_family == AF_UNKNOWN)
 232                                         update_address_ipv4(c, c->buffer + offset + 4, c->buffer + offset + 8);
 233                                 replen += 4;
 234                                 break;
 235                         case 0x03: // Hostname
 236                                 if(c->address.sa.sa_family == AF_UNKNOWN)
 237                                         update_address_ipv4(c, "\0\0\0\1", "\0\0");
 238                                 replen += ((uint8_t *)c->buffer)[offset + 4];
 239                                 break;
 240                         case 0x04: // IPv6
 241                                 if(c->address.sa.sa_family == AF_UNKNOWN)
 242                                         update_address_ipv6(c, c->buffer + offset + 4, c->buffer + offset + 20);
 243                                 replen += 16;
 244                                 break;
 245                         default:
 246                                 logger(LOG_ERR, "Proxy reply malformed");
 247                                 return -1;
 248                 }
 249                 if(c->buflen < replen) {
 250                         return 0;
 251                 } else {
 252                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 253                         c->allow_request = ID;
 254                         c->status.proxy_passed = true;
 255                         send_id(c);
 256                         return replen;
 257                 }
 258
 259         case PROXY_HTTP: {
 260                 char *p = memchr(c->buffer, '\n', c->buflen);
 261                 if(!p || p - c->buffer >= c->buflen)
 262                         return 0;
 263
 264                 while((p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer)))) {
 265                         if(p > c->buffer + 3 && !memcmp(p - 3, "\r\n\r\n", 4))
 266                                 break;
 267                 }
 268
 269                 if(!p)
 270                         return 0;
 271
 272                 if(c->buflen < 9)
 273                         return 0;
 274
 275                 if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
 276                         if(!strncmp(c->buffer + 9, "200", 3)) {
 277                                 if(c->address.sa.sa_family == AF_UNKNOWN)
 278                                         update_address_ipv4(c, "\0\0\0\1", "\0\0");
 279                                 logger(LOG_DEBUG, "Proxy request granted");
 280                                 replen = p  + 1 - c->buffer;
 281                                 c->allow_request = ID;
 282                                 c->status.proxy_passed = true;
 283                                 send_id(c);
 284                                 return replen;
 285                         } else {
 286                                 p = memchr(c->buffer, '\n', c->buflen);
 287                                 p[-1] = 0;
 288                                 logger(LOG_ERR, "Proxy request rejected: %s", c->buffer + 9);
 289                                 return false;
 290                         }
 291                 } else {
 292                         logger(LOG_ERR, "Proxy reply malformed");
 293                         return -1;
 294                 }
 295         }
 296
 297         default:
 298                 abort();
 299         }
 300 }