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         cp();
  73
  74         /* Use vsnprintf instead of vxasprintf: faster, no memory
  75            fragmentation, cleanup is automatic, and there is a limit on the
  76            input buffer anyway */
  77
  78         va_start(args, format);
  79         len = vsnprintf(buffer, MAXBUFSIZE, format, args);
  80         va_end(args);
  81
  82         if(len < 0 || len > MAXBUFSIZE - 1) {
  83                 logger(LOG_ERR, _("Output buffer overflow while sending request to %s (%s)"),
  84                            c->name, c->hostname);
  85                 return false;
  86         }
  87
  88         ifdebug(PROTOCOL) {
  89                 sscanf(buffer, "%d", &request);
  90                 ifdebug(META)
  91                         logger(LOG_DEBUG, _("Sending %s to %s (%s): %s"),
  92                                    request_name[request], c->name, c->hostname, buffer);
  93                 else
  94                         logger(LOG_DEBUG, _("Sending %s to %s (%s)"), request_name[request],
  95                                    c->name, c->hostname);
  96         }
  97
  98         buffer[len++] = '\n';
  99
 100         if(c == broadcast) {
 101                 broadcast_meta(NULL, buffer, len);
 102                 return true;
 103         } else
 104                 return send_meta(c, buffer, len);
 105 }
 106
 107 void forward_request(connection_t *from) {
 108         int request;
 109
 110         cp();
 111
 112         ifdebug(PROTOCOL) {
 113                 sscanf(from->buffer, "%d", &request);
 114                 ifdebug(META)
 115                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s): %s"),
 116                                    request_name[request], from->name, from->hostname,
 117                                    from->buffer);
 118                 else
 119                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s)"),
 120                                    request_name[request], from->name, from->hostname);
 121         }
 122
 123         from->buffer[from->reqlen - 1] = '\n';
 124
 125         broadcast_meta(from, from->buffer, from->reqlen);
 126 }
 127
 128 bool receive_request(connection_t *c) {
 129         int request;
 130
 131         cp();
 132
 133         if(sscanf(c->buffer, "%d", &request) == 1) {
 134                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 135                         ifdebug(META)
 136                                 logger(LOG_DEBUG, _("Unknown request from %s (%s): %s"),
 137                                            c->name, c->hostname, c->buffer);
 138                         else
 139                                 logger(LOG_ERR, _("Unknown request from %s (%s)"),
 140                                            c->name, c->hostname);
 141
 142                         return false;
 143                 } else {
 144                         ifdebug(PROTOCOL) {
 145                                 ifdebug(META)
 146                                         logger(LOG_DEBUG, _("Got %s from %s (%s): %s"),
 147                                                    request_name[request], c->name, c->hostname,
 148                                                    c->buffer);
 149                                 else
 150                                         logger(LOG_DEBUG, _("Got %s from %s (%s)"),
 151                                                    request_name[request], c->name, c->hostname);
 152                         }
 153                 }
 154
 155                 if((c->allow_request != ALL) && (c->allow_request != request)) {
 156                         logger(LOG_ERR, _("Unauthorized request from %s (%s)"), c->name,
 157                                    c->hostname);
 158                         return false;
 159                 }
 160
 161                 if(!request_handlers[request](c)) {
 162                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 163
 164                         logger(LOG_ERR, _("Error while processing %s from %s (%s)"),
 165                                    request_name[request], c->name, c->hostname);
 166                         return false;
 167                 }
 168         } else {
 169                 logger(LOG_ERR, _("Bogus data received from %s (%s)"),
 170                            c->name, c->hostname);
 171                 return false;
 172         }
 173
 174         return true;
 175 }
 176
 177 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 178         return strcmp(a->request, b->request);
 179 }
 180
 181 static void free_past_request(past_request_t *r) {
 182         cp();
 183
 184         if(r->request)
 185                 free(r->request);
 186
 187         free(r);
 188 }
 189
 190 void init_requests(void) {
 191         cp();
 192
 193         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 194 }
 195
 196 void exit_requests(void) {
 197         cp();
 198
 199         avl_delete_tree(past_request_tree);
 200 }
 201
 202 bool seen_request(char *request) {
 203         past_request_t *new, p = {0};
 204
 205         cp();
 206
 207         p.request = request;
 208
 209         if(avl_search(past_request_tree, &p)) {
 210                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Already seen request"));
 211                 return true;
 212         } else {
 213                 new = xmalloc(sizeof(*new));
 214                 new->request = xstrdup(request);
 215                 new->firstseen = now;
 216                 avl_insert(past_request_tree, new);
 217                 return false;
 218         }
 219 }
 220
 221 void age_past_requests(void) {
 222         avl_node_t *node, *next;
 223         past_request_t *p;
 224         int left = 0, deleted = 0;
 225
 226         cp();
 227
 228         for(node = past_request_tree->head; node; node = next) {
 229                 next = node->next;
 230                 p = node->data;
 231
 232                 if(p->firstseen + pinginterval < now)
 233                         avl_delete_node(past_request_tree, node), deleted++;
 234                 else
 235                         left++;
 236         }
 237
 238         if(left || deleted)
 239                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Aging past requests: deleted %d, left %d"),
 240                            deleted, left);
 241 }