src/meta.c

   1 /*
   2     meta.c -- handle the meta communication
   3     Copyright (C) 2000-2009 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 #ifdef EWOULDBLOCK
  98                         } else if(errno == EWOULDBLOCK) {
  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 #endif
 103                         } else {
 104                                 logger(LOG_ERR, "Flushing meta data to %s (%s) failed: %s", c->name,
 105                                            c->hostname, strerror(errno));
 106                         }
 107
 108                         return false;
 109                 }
 110
 111                 c->outbufstart += result;
 112                 c->outbuflen -= result;
 113         }
 114
 115         c->outbufstart = 0; /* avoid unnecessary memmoves */
 116         return true;
 117 }
 118
 119 void broadcast_meta(connection_t *from, const char *buffer, int length) {
 120         avl_node_t *node;
 121         connection_t *c;
 122
 123         for(node = connection_tree->head; node; node = node->next) {
 124                 c = node->data;
 125
 126                 if(c != from && c->status.active)
 127                         send_meta(c, buffer, length);
 128         }
 129 }
 130
 131 bool receive_meta(connection_t *c) {
 132         int oldlen, i, result;
 133         int lenin, lenout, reqlen;
 134         bool decrypted = false;
 135         char inbuf[MAXBUFSIZE];
 136
 137         /* Strategy:
 138            - Read as much as possible from the TCP socket in one go.
 139            - Decrypt it.
 140            - Check if a full request is in the input buffer.
 141            - If yes, process request and remove it from the buffer,
 142            then check again.
 143            - If not, keep stuff in buffer and exit.
 144          */
 145
 146         lenin = recv(c->socket, c->buffer + c->buflen, MAXBUFSIZE - c->buflen, 0);
 147
 148         if(lenin <= 0) {
 149                 if(!lenin || !errno) {
 150                         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection closed by %s (%s)",
 151                                            c->name, c->hostname);
 152                 } else if(errno == EINTR)
 153                         return true;
 154                 else
 155                         logger(LOG_ERR, "Metadata socket read error for %s (%s): %s",
 156                                    c->name, c->hostname, strerror(errno));
 157
 158                 return false;
 159         }
 160
 161         oldlen = c->buflen;
 162         c->buflen += lenin;
 163
 164         while(lenin > 0) {
 165                 /* Decrypt */
 166
 167                 if(c->status.decryptin && !decrypted) {
 168                         result = EVP_DecryptUpdate(c->inctx, (unsigned char *)inbuf, &lenout, (unsigned char *)c->buffer + oldlen, lenin);
 169                         if(!result || lenout != lenin) {
 170                                 logger(LOG_ERR, "Error while decrypting metadata from %s (%s): %s",
 171                                                 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
 172                                 return false;
 173                         }
 174                         memcpy(c->buffer + oldlen, inbuf, lenin);
 175                         decrypted = true;
 176                 }
 177
 178                 /* Are we receiving a TCPpacket? */
 179
 180                 if(c->tcplen) {
 181                         if(c->tcplen <= c->buflen) {
 182                                 receive_tcppacket(c, c->buffer, c->tcplen);
 183
 184                                 c->buflen -= c->tcplen;
 185                                 lenin -= c->tcplen - oldlen;
 186                                 memmove(c->buffer, c->buffer + c->tcplen, c->buflen);
 187                                 oldlen = 0;
 188                                 c->tcplen = 0;
 189                                 continue;
 190                         } else {
 191                                 break;
 192                         }
 193                 }
 194
 195                 /* Otherwise we are waiting for a request */
 196
 197                 reqlen = 0;
 198
 199                 for(i = oldlen; i < c->buflen; i++) {
 200                         if(c->buffer[i] == '\n') {
 201                                 c->buffer[i] = '\0';    /* replace end-of-line by end-of-string so we can use sscanf */
 202                                 reqlen = i + 1;
 203                                 break;
 204                         }
 205                 }
 206
 207                 if(reqlen) {
 208                         c->reqlen = reqlen;
 209                         if(!receive_request(c))
 210                                 return false;
 211
 212                         c->buflen -= reqlen;
 213                         lenin -= reqlen - oldlen;
 214                         memmove(c->buffer, c->buffer + reqlen, c->buflen);
 215                         oldlen = 0;
 216                         continue;
 217                 } else {
 218                         break;
 219                 }
 220         }
 221
 222         if(c->buflen >= MAXBUFSIZE) {
 223                 logger(LOG_ERR, "Metadata read buffer overflow for %s (%s)",
 224                            c->name, c->hostname);
 225                 return false;
 226         }
 227
 228         return true;
 229 }