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

   1 /*
   2     protocol.c -- handle the meta-protocol, basic functions
   3     Copyright (C) 1999-2001 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000,2001 Guus Sliepen <guus@sliepen.eu.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: protocol.c,v 1.28.4.147 2003/08/28 21:05:10 guus Exp $
  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 /* 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 {
  58         for(; *id; id++)
  59                 if(!isalnum(*id) && *id != '_')
  60                         return false;
  61
  62         return true;
  63 }
  64
  65 /* Generic request routines - takes care of logging and error
  66    detection as well */
  67
  68 bool send_request(connection_t *c, const char *format, ...)
  69 {
  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 {
 111         int request;
 112
 113         cp();
 114
 115         ifdebug(PROTOCOL) {
 116                 sscanf(from->buffer, "%d", &request);
 117                 ifdebug(META)
 118                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s): %s"),
 119                                    request_name[request], from->name, from->hostname,
 120                                    from->buffer);
 121                 else
 122                         logger(LOG_DEBUG, _("Forwarding %s from %s (%s)"),
 123                                    request_name[request], from->name, from->hostname);
 124         }
 125
 126         from->buffer[from->reqlen - 1] = '\n';
 127
 128         broadcast_meta(from, from->buffer, from->reqlen);
 129 }
 130
 131 bool receive_request(connection_t *c)
 132 {
 133         int request;
 134
 135         cp();
 136
 137         if(sscanf(c->buffer, "%d", &request) == 1) {
 138                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 139                         ifdebug(META)
 140                                 logger(LOG_DEBUG, _("Unknown request from %s (%s): %s"),
 141                                            c->name, c->hostname, c->buffer);
 142                         else
 143                                 logger(LOG_ERR, _("Unknown request from %s (%s)"),
 144                                            c->name, c->hostname);
 145
 146                         return false;
 147                 } else {
 148                         ifdebug(PROTOCOL) {
 149                                 ifdebug(META)
 150                                         logger(LOG_DEBUG, _("Got %s from %s (%s): %s"),
 151                                                    request_name[request], c->name, c->hostname,
 152                                                    c->buffer);
 153                                 else
 154                                         logger(LOG_DEBUG, _("Got %s from %s (%s)"),
 155                                                    request_name[request], c->name, c->hostname);
 156                         }
 157                 }
 158
 159                 if((c->allow_request != ALL) && (c->allow_request != request)) {
 160                         logger(LOG_ERR, _("Unauthorized request from %s (%s)"), c->name,
 161                                    c->hostname);
 162                         return false;
 163                 }
 164
 165                 if(!request_handlers[request](c)) {
 166                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 167
 168                         logger(LOG_ERR, _("Error while processing %s from %s (%s)"),
 169                                    request_name[request], c->name, c->hostname);
 170                         return false;
 171                 }
 172         } else {
 173                 logger(LOG_ERR, _("Bogus data received from %s (%s)"),
 174                            c->name, c->hostname);
 175                 return false;
 176         }
 177
 178         return true;
 179 }
 180
 181 static int past_request_compare(const past_request_t *a, const past_request_t *b)
 182 {
 183         return strcmp(a->request, b->request);
 184 }
 185
 186 static void free_past_request(past_request_t *r)
 187 {
 188         cp();
 189
 190         if(r->request)
 191                 free(r->request);
 192
 193         free(r);
 194 }
 195
 196 void init_requests(void)
 197 {
 198         cp();
 199
 200         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 201 }
 202
 203 void exit_requests(void)
 204 {
 205         cp();
 206
 207         avl_delete_tree(past_request_tree);
 208 }
 209
 210 bool seen_request(char *request)
 211 {
 212         past_request_t *new, p = {0};
 213
 214         cp();
 215
 216         p.request = request;
 217
 218         if(avl_search(past_request_tree, &p)) {
 219                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Already seen request"));
 220                 return true;
 221         } else {
 222                 new = xmalloc(sizeof(*new));
 223                 new->request = xstrdup(request);
 224                 new->firstseen = now;
 225                 avl_insert(past_request_tree, new);
 226                 return false;
 227         }
 228 }
 229
 230 void age_past_requests(void)
 231 {
 232         avl_node_t *node, *next;
 233         past_request_t *p;
 234         int left = 0, deleted = 0;
 235
 236         cp();
 237
 238         for(node = past_request_tree->head; node; node = next) {
 239                 next = node->next;
 240                 p = node->data;
 241
 242                 if(p->firstseen + pingtimeout < now)
 243                         avl_delete_node(past_request_tree, node), deleted++;
 244                 else
 245                         left++;
 246         }
 247
 248         if(left || deleted)
 249                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Aging past requests: deleted %d, left %d"),
 250                            deleted, left);
 251 }