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

   1 /*
   2     meta.c -- handle the meta communication
   3     Copyright (C) 2000-2014 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 "proxy.h"
  34 #include "utils.h"
  35 #include "xalloc.h"
  36
  37 bool send_meta(connection_t *c, const char *buffer, int length) {
  38         int outlen;
  39         int result;
  40
  41         if(!c) {
  42                 logger(LOG_ERR, "send_meta() called with NULL pointer!");
  43                 abort();
  44         }
  45
  46         ifdebug(META) logger(LOG_DEBUG, "Sending %d bytes of metadata to %s (%s)", length,
  47                            c->name, c->hostname);
  48
  49         if(!c->outbuflen)
  50                 c->last_flushed_time = now;
  51
  52         /* Find room in connection's buffer */
  53         if(length + c->outbuflen > c->outbufsize) {
  54                 c->outbufsize = length + c->outbuflen;
  55                 c->outbuf = xrealloc(c->outbuf, c->outbufsize);
  56         }
  57
  58         if(length + c->outbuflen + c->outbufstart > c->outbufsize) {
  59                 memmove(c->outbuf, c->outbuf + c->outbufstart, c->outbuflen);
  60                 c->outbufstart = 0;
  61         }
  62
  63         /* Add our data to buffer */
  64         if(c->status.encryptout) {
  65                 result = EVP_EncryptUpdate(c->outctx, (unsigned char *)c->outbuf + c->outbufstart + c->outbuflen,
  66                                 &outlen, (unsigned char *)buffer, length);
  67                 if(!result || outlen < length) {
  68                         logger(LOG_ERR, "Error while encrypting metadata to %s (%s): %s",
  69                                         c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
  70                         return false;
  71                 } else if(outlen > length) {
  72                         logger(LOG_EMERG, "Encrypted data too long! Heap corrupted!");
  73                         abort();
  74                 }
  75                 c->outbuflen += outlen;
  76         } else {
  77                 memcpy(c->outbuf + c->outbufstart + c->outbuflen, buffer, length);
  78                 c->outbuflen += length;
  79         }
  80
  81         return true;
  82 }
  83
  84 bool flush_meta(connection_t *c) {
  85         int result;
  86
  87         ifdebug(META) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s)",
  88                          c->outbuflen, c->name, c->hostname);
  89
  90         while(c->outbuflen) {
  91                 result = send(c->socket, c->outbuf + c->outbufstart, c->outbuflen, 0);
  92                 if(result <= 0) {
  93                         if(!errno || errno == EPIPE) {
  94                                 ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
  95                                                    c->name, c->hostname);
  96                         } else if(errno == EINTR) {
  97                                 continue;
  98                         } else if(sockwouldblock(sockerrno)) {
  99                                 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Flushing %d bytes to %s (%s) would block",
 100                                                 c->outbuflen, c->name, c->hostname);
 101                                 return true;
 102                         } else {
 103                                 logger(LOG_ERR, "Flushing meta data to %s (%s) failed: %s", c->name,
 104                                            c->hostname, sockstrerror(sockerrno));
 105                         }
 106
 107                         return false;
 108                 }
 109
 110                 c->outbufstart += result;
 111                 c->outbuflen -= result;
 112         }
 113
 114         c->outbufstart = 0; /* avoid unnecessary memmoves */
 115         return true;
 116 }
 117
 118 void broadcast_meta(connection_t *from, const char *buffer, int length) {
 119         avl_node_t *node;
 120         connection_t *c;
 121
 122         for(node = connection_tree->head; node; node = node->next) {
 123                 c = node->data;
 124
 125                 if(c != from && c->status.active)
 126                         send_meta(c, buffer, length);
 127         }
 128 }
 129
 130 bool receive_meta(connection_t *c) {
 131         int oldlen, i, result;
 132         int lenin, lenout, reqlen;
 133         bool decrypted = false;
 134         char inbuf[MAXBUFSIZE];
 135
 136         /* Strategy:
 137            - Read as much as possible from the TCP socket in one go.
 138            - Decrypt it.
 139            - Check if a full request is in the input buffer.
 140            - If yes, process request and remove it from the buffer,
 141            then check again.
 142            - If not, keep stuff in buffer and exit.
 143          */
 144
 145         lenin = recv(c->socket, c->buffer + c->buflen, MAXBUFSIZE - c->buflen, 0);
 146
 147         if(lenin <= 0) {
 148                 if(!lenin || !errno) {
 149                         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
 150                                            c->name, c->hostname);
 151                 } else if(sockwouldblock(sockerrno))
 152                         return true;
 153                 else
 154                         logger(LOG_ERR, "Metadata socket read error for %s (%s): %s",
 155                                    c->name, c->hostname, sockstrerror(sockerrno));
 156
 157                 return false;
 158         }
 159
 160         oldlen = c->buflen;
 161         c->buflen += lenin;
 162
 163         while(lenin > 0) {
 164                 reqlen = 0;
 165
 166                 /* Is it proxy metadata? */
 167
 168                 if(c->allow_request == PROXY) {
 169                         reqlen = receive_proxy_meta(c, oldlen, lenin);
 170                         if(reqlen < 0)
 171                                 return false;
 172                         goto consume;
 173                 }
 174
 175                 /* Decrypt */
 176
 177                 if(c->status.decryptin && !decrypted) {
 178                         result = EVP_DecryptUpdate(c->inctx, (unsigned char *)inbuf, &lenout, (unsigned char *)c->buffer + oldlen, lenin);
 179                         if(!result || lenout != lenin) {
 180                                 logger(LOG_ERR, "Error while decrypting metadata from %s (%s): %s",
 181                                                 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
 182                                 return false;
 183                         }
 184                         memcpy(c->buffer + oldlen, inbuf, lenin);
 185                         decrypted = true;
 186                 }
 187
 188                 /* Are we receiving a TCPpacket? */
 189
 190                 if(c->tcplen) {
 191                         if(c->tcplen <= c->buflen) {
 192                                 if(c->allow_request != ALL) {
 193                                         logger(LOG_ERR, "Got unauthorized TCP packet from %s (%s)", c->name, c->hostname);
 194                                         return false;
 195                                 }
 196
 197                                 receive_tcppacket(c, c->buffer, c->tcplen);
 198                                 reqlen = c->tcplen;
 199                                 c->tcplen = 0;
 200                         }
 201                 } else {
 202                         /* Otherwise we are waiting for a request */
 203
 204                         for(i = oldlen; i < c->buflen; i++) {
 205                                 if(c->buffer[i] == '\n') {
 206                                         c->buffer[i] = '\0';    /* replace end-of-line by end-of-string so we can use sscanf */
 207                                         c->reqlen = reqlen = i + 1;
 208                                         break;
 209                                 }
 210                         }
 211
 212                         if(reqlen && !receive_request(c))
 213                                 return false;
 214                 }
 215
 216 consume:
 217                 if(reqlen) {
 218                         c->buflen -= reqlen;
 219                         lenin -= reqlen - oldlen;
 220                         memmove(c->buffer, c->buffer + reqlen, c->buflen);
 221                         oldlen = 0;
 222                         continue;
 223                 } else {
 224                         break;
 225                 }
 226         }
 227
 228         if(c->buflen >= MAXBUFSIZE) {
 229                 logger(LOG_ERR, "Metadata read buffer overflow for %s (%s)",
 230                            c->name, c->hostname);
 231                 return false;
 232         }
 233
 234         return true;
 235 }