tinc-vpn.org Git - tinc/blob - src/protocol.c

   1 /*
   2     protocol.c -- handle the meta-protocol, basic functions
   3     Copyright (C) 1999-2005 Ivo Timmermans,
   4                   2000-2009 Guus Sliepen <guus@tinc-vpn.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include "conf.h"
  24 #include "connection.h"
  25 #include "logger.h"
  26 #include "meta.h"
  27 #include "protocol.h"
  28 #include "utils.h"
  29 #include "xalloc.h"
  30
  31 bool tunnelserver = false;
  32
  33 /* Jumptable for the request handlers */
  34
  35 static bool (*request_handlers[])(connection_t *) = {
  36                 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
  37                 status_h, error_h, termreq_h,
  38                 ping_h, pong_h,
  39                 add_subnet_h, del_subnet_h,
  40                 add_edge_h, del_edge_h,
  41                 key_changed_h, req_key_h, ans_key_h, tcppacket_h,
  42 };
  43
  44 /* Request names */
  45
  46 static char (*request_name[]) = {
  47                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
  48                 "STATUS", "ERROR", "TERMREQ",
  49                 "PING", "PONG",
  50                 "ADD_SUBNET", "DEL_SUBNET",
  51                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET",
  52 };
  53
  54 static avl_tree_t *past_request_tree;
  55
  56 bool check_id(const char *id) {
  57         for(; *id; id++)
  58                 if(!isalnum(*id) && *id != '_')
  59                         return false;
  60
  61         return true;
  62 }
  63
  64 /* Generic request routines - takes care of logging and error
  65    detection as well */
  66
  67 bool send_request(connection_t *c, const char *format, ...) {
  68         va_list args;
  69         char buffer[MAXBUFSIZE];
  70         int len, request;
  71
  72         /* Use vsnprintf instead of vxasprintf: faster, no memory
  73            fragmentation, cleanup is automatic, and there is a limit on the
  74            input buffer anyway */
  75
  76         va_start(args, format);
  77         len = vsnprintf(buffer, MAXBUFSIZE, format, args);
  78         va_end(args);
  79
  80         if(len < 0 || len > MAXBUFSIZE - 1) {
  81                 logger(LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
  82                            c->name, c->hostname);
  83                 return false;
  84         }
  85
  86         ifdebug(PROTOCOL) {
  87                 sscanf(buffer, "%d", &request);
  88                 ifdebug(META)
  89                         logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
  90                                    request_name[request], c->name, c->hostname, buffer);
  91                 else
  92                         logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[request],
  93                                    c->name, c->hostname);
  94         }
  95
  96         buffer[len++] = '\n';
  97
  98         if(c == broadcast) {
  99                 broadcast_meta(NULL, buffer, len);
 100                 return true;
 101         } else
 102                 return send_meta(c, buffer, len);
 103 }
 104
 105 void forward_request(connection_t *from) {
 106         int request;
 107
 108         ifdebug(PROTOCOL) {
 109                 sscanf(from->buffer, "%d", &request);
 110                 ifdebug(META)
 111                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 112                                    request_name[request], from->name, from->hostname,
 113                                    from->buffer);
 114                 else
 115                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 116                                    request_name[request], from->name, from->hostname);
 117         }
 118
 119         from->buffer[from->reqlen - 1] = '\n';
 120
 121         broadcast_meta(from, from->buffer, from->reqlen);
 122 }
 123
 124 bool receive_request(connection_t *c) {
 125         int request;
 126
 127         if(sscanf(c->buffer, "%d", &request) == 1) {
 128                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 129                         ifdebug(META)
 130                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 131                                            c->name, c->hostname, c->buffer);
 132                         else
 133                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 134                                            c->name, c->hostname);
 135
 136                         return false;
 137                 } else {
 138                         ifdebug(PROTOCOL) {
 139                                 ifdebug(META)
 140                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 141                                                    request_name[request], c->name, c->hostname,
 142                                                    c->buffer);
 143                                 else
 144                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 145                                                    request_name[request], c->name, c->hostname);
 146                         }
 147                 }
 148
 149                 if((c->allow_request != ALL) && (c->allow_request != request)) {
 150                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 151                                    c->hostname);
 152                         return false;
 153                 }
 154
 155                 if(!request_handlers[request](c)) {
 156                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 157
 158                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 159                                    request_name[request], c->name, c->hostname);
 160                         return false;
 161                 }
 162         } else {
 163                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 164                            c->name, c->hostname);
 165                 return false;
 166         }
 167
 168         return true;
 169 }
 170
 171 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 172         return strcmp(a->request, b->request);
 173 }
 174
 175 static void free_past_request(past_request_t *r) {
 176         if(r->request)
 177                 free(r->request);
 178
 179         free(r);
 180 }
 181
 182 void init_requests(void) {
 183         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 184 }
 185
 186 void exit_requests(void) {
 187         avl_delete_tree(past_request_tree);
 188 }
 189
 190 bool seen_request(char *request) {
 191         past_request_t *new, p = {0};
 192
 193         p.request = request;
 194
 195         if(avl_search(past_request_tree, &p)) {
 196                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 197                 return true;
 198         } else {
 199                 new = xmalloc(sizeof(*new));
 200                 new->request = xstrdup(request);
 201                 new->firstseen = now;
 202                 avl_insert(past_request_tree, new);
 203                 return false;
 204         }
 205 }
 206
 207 void age_past_requests(void) {
 208         avl_node_t *node, *next;
 209         past_request_t *p;
 210         int left = 0, deleted = 0;
 211
 212         for(node = past_request_tree->head; node; node = next) {
 213                 next = node->next;
 214                 p = node->data;
 215
 216                 if(p->firstseen + pinginterval < now)
 217                         avl_delete_node(past_request_tree, node), deleted++;
 218                 else
 219                         left++;
 220         }
 221
 222         if(left || deleted)
 223                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 224                            deleted, left);
 225 }