git.tinc-vpn.org Git - tinc/blob - src/meta.c

   1 /*
   2     meta.c -- handle the meta communication
   3     Copyright (C) 2000-2013 Guus Sliepen <guus@tinc-vpn.org>,
   4                   2000-2005 Ivo Timmermans
   5                   2006      Scott Lamb <slamb@slamb.org>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License along
  18     with this program; if not, write to the Free Software Foundation, Inc.,
  19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20 */
  21
  22 #include "system.h"
  23
  24 #include <openssl/err.h>
  25 #include <openssl/evp.h>
  26
  27 #include "avl_tree.h"
  28 #include "connection.h"
  29 #include "logger.h"
  30 #include "meta.h"
  31 #include "net.h"
  32 #include "protocol.h"
  33 #include "utils.h"
  34 #include "xalloc.h"
  35
  36 bool send_meta(connection_t *c, const char *buffer, int length) {
  37         int outlen;
  38         int result;
  39
  40         if(!c) {
  41                 logger(LOG_ERR, "send_meta() called with NULL pointer!");
  42                 abort();
  43         }
  44
  45         ifdebug(META) logger(LOG_DEBUG, "Sending %d bytes of metadata to %s (%s)", length,
  46                            c->name, c->hostname);
  47
  48         if(!c->outbuflen)
  49                 c->last_flushed_time = now;
  50
  51         /* Find room in connection's buffer */
  52         if(length + c->outbuflen > c->outbufsize) {
  53                 c->outbufsize = length + c->outbuflen;
  54                 c->outbuf = xrealloc(c->outbuf, c->outbufsize);
  55         }
  56
  57         if(length + c->outbuflen + c->outbufstart > c->outbufsize) {
  58                 memmove(c->outbuf, c->outbuf + c->outbufstart, c->outbuflen);
  59                 c->outbufstart = 0;
  60         }
  61
  62         /* Add our data to buffer */
  63         if(c->status.encryptout) {
  64                 result = EVP_EncryptUpdate(c->outctx, (unsigned char *)c->outbuf + c->outbufstart + c->outbuflen,
  65                                 &outlen, (unsigned char *)buffer, length);
  66                 if(!result || outlen < length) {
  67                         logger(LOG_ERR, "Error while encrypting metadata to %s (%s): %s",
  68                                         c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
  69                         return false;
  70                 } else if(outlen > length) {
  71                         logger(LOG_EMERG, "Encrypted data too long! Heap corrupted!");
  72                         abort();
  73                 }
  74                 c->outbuflen += outlen;
  75         } else {
  76                 memcpy(c->outbuf + c->outbufstart + c->outbuflen, buffer, length);
  77                 c->outbuflen += length;
  78         }
  79
  80         return true;
  81 }
  82
  83 bool flush_meta(connection_t *c) {
  84         int result;
  85
  86         ifdebug(META) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s)",
  87                          c->outbuflen, c->name, c->hostname);
  88
  89         while(c->outbuflen) {
  90                 result = send(c->socket, c->outbuf + c->outbufstart, c->outbuflen, 0);
  91                 if(result <= 0) {
  92                         if(!errno || errno == EPIPE) {
  93                                 ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
  94                                                    c->name, c->hostname);
  95                         } else if(errno == EINTR) {
  96                                 continue;
  97                         } else if(sockwouldblock(sockerrno)) {
  98                                 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s) would block",
  99                                                 c->outbuflen, c->name, c->hostname);
 100                                 return true;
 101                         } else {
 102                                 logger(LOG_ERR, "Flushing meta data to %s (%s) failed: %s", c->name,
 103                                            c->hostname, sockstrerror(sockerrno));
 104                         }
 105
 106                         return false;
 107                 }
 108
 109                 c->outbufstart += result;
 110                 c->outbuflen -= result;
 111         }
 112
 113         c->outbufstart = 0; /* avoid unnecessary memmoves */
 114         return true;
 115 }
 116
 117 void broadcast_meta(connection_t *from, const char *buffer, int length) {
 118         avl_node_t *node;
 119         connection_t *c;
 120
 121         for(node = connection_tree->head; node; node = node->next) {
 122                 c = node->data;
 123
 124                 if(c != from && c->status.active)
 125                         send_meta(c, buffer, length);
 126         }
 127 }
 128
 129 bool receive_meta(connection_t *c) {
 130         int oldlen, i, result;
 131         int lenin, lenout, reqlen;
 132         bool decrypted = false;
 133         char inbuf[MAXBUFSIZE];
 134
 135         /* Strategy:
 136            - Read as much as possible from the TCP socket in one go.
 137            - Decrypt it.
 138            - Check if a full request is in the input buffer.
 139            - If yes, process request and remove it from the buffer,
 140            then check again.
 141            - If not, keep stuff in buffer and exit.
 142          */
 143
 144         lenin = recv(c->socket, c->buffer + c->buflen, MAXBUFSIZE - c->buflen, 0);
 145
 146         if(lenin <= 0) {
 147                 if(!lenin || !errno) {
 148                         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
 149                                            c->name, c->hostname);
 150                 } else if(sockwouldblock(sockerrno))
 151                         return true;
 152                 else
 153                         logger(LOG_ERR, "Metadata socket read error for %s (%s): %s",
 154                                    c->name, c->hostname, sockstrerror(sockerrno));
 155
 156                 return false;
 157         }
 158
 159         oldlen = c->buflen;
 160         c->buflen += lenin;
 161
 162         while(lenin > 0) {
 163                 /* Decrypt */
 164
 165                 if(c->status.decryptin && !decrypted) {
 166                         result = EVP_DecryptUpdate(c->inctx, (unsigned char *)inbuf, &lenout, (unsigned char *)c->buffer + oldlen, lenin);
 167                         if(!result || lenout != lenin) {
 168                                 logger(LOG_ERR, "Error while decrypting metadata from %s (%s): %s",
 169                                                 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
 170                                 return false;
 171                         }
 172                         memcpy(c->buffer + oldlen, inbuf, lenin);
 173                         decrypted = true;
 174                 }
 175
 176                 /* Are we receiving a TCPpacket? */
 177
 178                 if(c->tcplen) {
 179                         if(c->tcplen <= c->buflen) {
 180                                 if(!c->node) {
 181                                         if(c->outgoing && proxytype == PROXY_SOCKS4 && c->allow_request == ID) {
 182                                                 if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
 183                                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 184                                                 } else {
 185                                                         logger(LOG_ERR, "Proxy request rejected");
 186                                                         return false;
 187                                                 }
 188                                         } else if(c->outgoing && proxytype == PROXY_SOCKS5 && c->allow_request == ID) {
 189                                                 if(c->buffer[0] != 5) {
 190                                                         logger(LOG_ERR, "Invalid response from proxy server");
 191                                                         return false;
 192                                                 }
 193                                                 if(c->buffer[1] == (char)0xff) {
 194                                                         logger(LOG_ERR, "Proxy request rejected: unsuitable authentication method");
 195                                                         return false;
 196                                                 }
 197                                                 if(c->buffer[2] != 5) {
 198                                                         logger(LOG_ERR, "Invalid response from proxy server");
 199                                                         return false;
 200                                                 }
 201                                                 if(c->buffer[3] == 0) {
 202                                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
 203                                                 } else {
 204                                                         logger(LOG_ERR, "Proxy request rejected");
 205                                                         return false;
 206                                                 }
 207                                         } else {
 208                                                 logger(LOG_ERR, "c->tcplen set but c->node is NULL!");
 209                                                 abort();
 210                                         }
 211                                 } else {
 212                                         if(c->allow_request == ALL) {
 213                                                 receive_tcppacket(c, c->buffer, c->tcplen);
 214                                         } else {
 215                                                 logger(LOG_ERR, "Got unauthorized TCP packet from %s (%s)", c->name, c->hostname);
 216                                                 return false;
 217                                         }
 218                                 }
 219
 220                                 c->buflen -= c->tcplen;
 221                                 lenin -= c->tcplen - oldlen;
 222                                 memmove(c->buffer, c->buffer + c->tcplen, c->buflen);
 223                                 oldlen = 0;
 224                                 c->tcplen = 0;
 225                                 continue;
 226                         } else {
 227                                 break;
 228                         }
 229                 }
 230
 231                 /* Otherwise we are waiting for a request */
 232
 233                 reqlen = 0;
 234
 235                 for(i = oldlen; i < c->buflen; i++) {
 236                         if(c->buffer[i] == '\n') {
 237                                 c->buffer[i] = '\0';    /* replace end-of-line by end-of-string so we can use sscanf */
 238                                 reqlen = i + 1;
 239                                 break;
 240                         }
 241                 }
 242
 243                 if(reqlen) {
 244                         c->reqlen = reqlen;
 245                         if(!receive_request(c))
 246                                 return false;
 247
 248                         c->buflen -= reqlen;
 249                         lenin -= reqlen - oldlen;
 250                         memmove(c->buffer, c->buffer + reqlen, c->buflen);
 251                         oldlen = 0;
 252                         continue;
 253                 } else {
 254                         break;
 255                 }
 256         }
 257
 258         if(c->buflen >= MAXBUFSIZE) {
 259                 logger(LOG_ERR, "Metadata read buffer overflow for %s (%s)",
 260                            c->name, c->hostname);
 261                 return false;
 262         }
 263
 264         return true;
 265 }