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                   2000-2006 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
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id$
  21 */
  22
  23 #include "system.h"
  24
  25 #include "conf.h"
  26 #include "connection.h"
  27 #include "logger.h"
  28 #include "meta.h"
  29 #include "protocol.h"
  30 #include "utils.h"
  31 #include "xalloc.h"
  32
  33 bool tunnelserver = false;
  34
  35 /* Jumptable for the request handlers */
  36
  37 static bool (*request_handlers[])(connection_t *) = {
  38                 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
  39                 status_h, error_h, termreq_h,
  40                 ping_h, pong_h,
  41                 add_subnet_h, del_subnet_h,
  42                 add_edge_h, del_edge_h,
  43                 key_changed_h, req_key_h, ans_key_h, tcppacket_h,
  44 };
  45
  46 /* Request names */
  47
  48 static char (*request_name[]) = {
  49                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
  50                 "STATUS", "ERROR", "TERMREQ",
  51                 "PING", "PONG",
  52                 "ADD_SUBNET", "DEL_SUBNET",
  53                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET",
  54 };
  55
  56 static avl_tree_t *past_request_tree;
  57
  58 bool check_id(const char *id) {
  59         for(; *id; id++)
  60                 if(!isalnum(*id) && *id != '_')
  61                         return false;
  62
  63         return true;
  64 }
  65
  66 /* Generic request routines - takes care of logging and error
  67    detection as well */
  68
  69 bool send_request(connection_t *c, const char *format, ...) {
  70         va_list args;
  71         char buffer[MAXBUFSIZE];
  72         int len, request;
  73
  74         cp();
  75
  76         /* Use vsnprintf instead of vasprintf: faster, no memory
  77            fragmentation, cleanup is automatic, and there is a limit on the
  78            input buffer anyway */
  79
  80         va_start(args, format);
  81         len = vsnprintf(buffer, MAXBUFSIZE, format, args);
  82         va_end(args);
  83
  84         if(len < 0 || len > MAXBUFSIZE - 1) {
  85                 logger(LOG_ERR, _("Output buffer overflow while sending request to %s (%s)"),
  86                            c->name, c->hostname);
  87                 return false;
  88         }
  89
  90         ifdebug(PROTOCOL) {
  91                 sscanf(buffer, "%d", &request);
  92                 ifdebug(META)
  93                         logger(LOG_DEBUG, _("Sending %s to %s (%s): %s"),
  94                                    request_name[request], c->name, c->hostname, buffer);
  95                 else
  96                         logger(LOG_DEBUG, _("Sending %s to %s (%s)"), request_name[request],
  97                                    c->name, c->hostname);
  98         }
  99
 100         buffer[len++] = '\n';
 101
 102         if(c == broadcast) {
 103                 broadcast_meta(NULL, buffer, len);
 104                 return true;
 105         } else
 106                 return send_meta(c, buffer, len);
 107 }
 108
 109 void forward_request(connection_t *from) {
 110         int request;
 111
 112         cp();
 113
 114         ifdebug(PROTOCOL) {
 115                 sscanf(from->buffer, "%d", &request);
 116                 ifdebug(META)
 117                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s): %s"),
 118                                    request_name[request], from->name, from->hostname,
 119                                    from->buffer);
 120                 else
 121                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s)"),
 122                                    request_name[request], from->name, from->hostname);
 123         }
 124
 125         from->buffer[from->reqlen - 1] = '\n';
 126
 127         broadcast_meta(from, from->buffer, from->reqlen);
 128 }
 129
 130 bool receive_request(connection_t *c) {
 131         int request;
 132
 133         cp();
 134
 135         if(sscanf(c->buffer, "%d", &request) == 1) {
 136                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 137                         ifdebug(META)
 138                                 logger(LOG_DEBUG, _("Unknown request from %s (%s): %s"),
 139                                            c->name, c->hostname, c->buffer);
 140                         else
 141                                 logger(LOG_ERR, _("Unknown request from %s (%s)"),
 142                                            c->name, c->hostname);
 143
 144                         return false;
 145                 } else {
 146                         ifdebug(PROTOCOL) {
 147                                 ifdebug(META)
 148                                         logger(LOG_DEBUG, _("Got %s from %s (%s): %s"),
 149                                                    request_name[request], c->name, c->hostname,
 150                                                    c->buffer);
 151                                 else
 152                                         logger(LOG_DEBUG, _("Got %s from %s (%s)"),
 153                                                    request_name[request], c->name, c->hostname);
 154                         }
 155                 }
 156
 157                 if((c->allow_request != ALL) && (c->allow_request != request)) {
 158                         logger(LOG_ERR, _("Unauthorized request from %s (%s)"), c->name,
 159                                    c->hostname);
 160                         return false;
 161                 }
 162
 163                 if(!request_handlers[request](c)) {
 164                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 165
 166                         logger(LOG_ERR, _("Error while processing %s from %s (%s)"),
 167                                    request_name[request], c->name, c->hostname);
 168                         return false;
 169                 }
 170         } else {
 171                 logger(LOG_ERR, _("Bogus data received from %s (%s)"),
 172                            c->name, c->hostname);
 173                 return false;
 174         }
 175
 176         return true;
 177 }
 178
 179 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 180         return strcmp(a->request, b->request);
 181 }
 182
 183 static void free_past_request(past_request_t *r) {
 184         cp();
 185
 186         if(r->request)
 187                 free(r->request);
 188
 189         free(r);
 190 }
 191
 192 static struct event past_request_event;
 193
 194 bool seen_request(char *request) {
 195         past_request_t *new, p = {0};
 196
 197         cp();
 198
 199         p.request = request;
 200
 201         if(avl_search(past_request_tree, &p)) {
 202                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Already seen request"));
 203                 return true;
 204         } else {
 205                 new = xmalloc(sizeof(*new));
 206                 new->request = xstrdup(request);
 207                 new->firstseen = time(NULL);
 208                 avl_insert(past_request_tree, new);
 209                 event_add(&past_request_event, &(struct timeval){10, 0});
 210                 return false;
 211         }
 212 }
 213
 214 void age_past_requests(int fd, short events, void *data) {
 215         avl_node_t *node, *next;
 216         past_request_t *p;
 217         int left = 0, deleted = 0;
 218         time_t now = time(NULL);
 219
 220         cp();
 221
 222         for(node = past_request_tree->head; node; node = next) {
 223                 next = node->next;
 224                 p = node->data;
 225
 226                 if(p->firstseen + pinginterval < now)
 227                         avl_delete_node(past_request_tree, node), deleted++;
 228                 else
 229                         left++;
 230         }
 231
 232         if(left || deleted)
 233                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Aging past requests: deleted %d, left %d"),
 234                            deleted, left);
 235
 236         if(left)
 237                 event_add(&past_request_event, &(struct timeval){10, 0});
 238 }
 239
 240 void init_requests(void) {
 241         cp();
 242
 243         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 244
 245         timeout_set(&past_request_event, age_past_requests, NULL);
 246 }
 247
 248 void exit_requests(void) {
 249         cp();
 250
 251         avl_delete_tree(past_request_tree);
 252
 253         event_del(&past_request_event);
 254 }