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 bool strictsubnets = false;
  33
  34 /* Jumptable for the request handlers */
  35
  36 static bool (*request_handlers[])(connection_t *, char *) = {
  37                 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
  38                 status_h, error_h, termreq_h,
  39                 ping_h, pong_h,
  40                 add_subnet_h, del_subnet_h,
  41                 add_edge_h, del_edge_h,
  42                 key_changed_h, req_key_h, ans_key_h, tcppacket_h, control_h,
  43 };
  44
  45 /* Request names */
  46
  47 static char (*request_name[]) = {
  48                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
  49                 "STATUS", "ERROR", "TERMREQ",
  50                 "PING", "PONG",
  51                 "ADD_SUBNET", "DEL_SUBNET",
  52                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET", "CONTROL",
  53 };
  54
  55 static splay_tree_t *past_request_tree;
  56
  57 bool check_id(const char *id) {
  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         va_list args;
  70         char request[MAXBUFSIZE];
  71         int len;
  72
  73         /* Use vsnprintf instead of vxasprintf: faster, no memory
  74            fragmentation, cleanup is automatic, and there is a limit on the
  75            input buffer anyway */
  76
  77         va_start(args, format);
  78         len = vsnprintf(request, MAXBUFSIZE, format, args);
  79         va_end(args);
  80
  81         if(len < 0 || len > MAXBUFSIZE - 1) {
  82                 logger(LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
  83                            c->name, c->hostname);
  84                 return false;
  85         }
  86
  87         ifdebug(PROTOCOL) {
  88                 ifdebug(META)
  89                         logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
  90                                    request_name[atoi(request)], c->name, c->hostname, request);
  91                 else
  92                         logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[atoi(request)],
  93                                    c->name, c->hostname);
  94         }
  95
  96         request[len++] = '\n';
  97
  98         if(c == broadcast) {
  99                 broadcast_meta(NULL, request, len);
 100                 return true;
 101         } else
 102                 return send_meta(c, request, len);
 103 }
 104
 105 void forward_request(connection_t *from, char *request) {
 106         ifdebug(PROTOCOL) {
 107                 ifdebug(META)
 108                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 109                                    request_name[atoi(request)], from->name, from->hostname, request);
 110                 else
 111                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 112                                    request_name[atoi(request)], from->name, from->hostname);
 113         }
 114
 115         int len = strlen(request);
 116         request[len] = '\n';
 117         broadcast_meta(from, request, len);
 118 }
 119
 120 bool receive_request(connection_t *c, char *request) {
 121         int reqno = atoi(request);
 122
 123         if(reqno || *request == '0') {
 124                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
 125                         ifdebug(META)
 126                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 127                                            c->name, c->hostname, request);
 128                         else
 129                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 130                                            c->name, c->hostname);
 131
 132                         return false;
 133                 } else {
 134                         ifdebug(PROTOCOL) {
 135                                 ifdebug(META)
 136                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 137                                                    request_name[reqno], c->name, c->hostname, request);
 138                                 else
 139                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 140                                                    request_name[reqno], c->name, c->hostname);
 141                         }
 142                 }
 143
 144                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 145                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 146                                    c->hostname);
 147                         return false;
 148                 }
 149
 150                 if(!request_handlers[reqno](c, request)) {
 151                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 152
 153                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 154                                    request_name[reqno], c->name, c->hostname);
 155                         return false;
 156                 }
 157         } else {
 158                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 159                            c->name, c->hostname);
 160                 return false;
 161         }
 162
 163         return true;
 164 }
 165
 166 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 167         return strcmp(a->request, b->request);
 168 }
 169
 170 static void free_past_request(past_request_t *r) {
 171         if(r->request)
 172                 free(r->request);
 173
 174         free(r);
 175 }
 176
 177 static struct event past_request_event;
 178
 179 bool seen_request(char *request) {
 180         past_request_t *new, p = {0};
 181
 182         p.request = request;
 183
 184         if(splay_search(past_request_tree, &p)) {
 185                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 186                 return true;
 187         } else {
 188                 new = xmalloc(sizeof *new);
 189                 new->request = xstrdup(request);
 190                 new->firstseen = time(NULL);
 191                 splay_insert(past_request_tree, new);
 192                 event_add(&past_request_event, &(struct timeval){10, 0});
 193                 return false;
 194         }
 195 }
 196
 197 void age_past_requests(int fd, short events, void *data) {
 198         splay_node_t *node, *next;
 199         past_request_t *p;
 200         int left = 0, deleted = 0;
 201         time_t now = time(NULL);
 202
 203         for(node = past_request_tree->head; node; node = next) {
 204                 next = node->next;
 205                 p = node->data;
 206
 207                 if(p->firstseen + pinginterval < now)
 208                         splay_delete_node(past_request_tree, node), deleted++;
 209                 else
 210                         left++;
 211         }
 212
 213         if(left || deleted)
 214                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 215                            deleted, left);
 216
 217         if(left)
 218                 event_add(&past_request_event, &(struct timeval){10, 0});
 219 }
 220
 221 void init_requests(void) {
 222         past_request_tree = splay_alloc_tree((splay_compare_t) past_request_compare, (splay_action_t) free_past_request);
 223
 224         timeout_set(&past_request_event, age_past_requests, NULL);
 225 }
 226
 227 void exit_requests(void) {
 228         splay_delete_tree(past_request_tree);
 229
 230         event_del(&past_request_event);
 231 }