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 *, char *) = {
  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 splay_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 request[MAXBUFSIZE];
  70         int len;
  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(request, 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                 ifdebug(META)
  88                         logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
  89                                    request_name[atoi(request)], c->name, c->hostname, request);
  90                 else
  91                         logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[atoi(request)],
  92                                    c->name, c->hostname);
  93         }
  94
  95         request[len++] = '\n';
  96
  97         if(c == broadcast) {
  98                 broadcast_meta(NULL, request, len);
  99                 return true;
 100         } else
 101                 return send_meta(c, request, len);
 102 }
 103
 104 void forward_request(connection_t *from, char *request) {
 105         ifdebug(PROTOCOL) {
 106                 ifdebug(META)
 107                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 108                                    request_name[atoi(request)], from->name, from->hostname, request);
 109                 else
 110                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 111                                    request_name[atoi(request)], from->name, from->hostname);
 112         }
 113
 114         int len = strlen(request);
 115         request[len] = '\n';
 116         broadcast_meta(from, request, len);
 117 }
 118
 119 bool receive_request(connection_t *c, char *request) {
 120         int reqno = atoi(request);
 121
 122         if(reqno || *request == '0') {
 123                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
 124                         ifdebug(META)
 125                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 126                                            c->name, c->hostname, request);
 127                         else
 128                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 129                                            c->name, c->hostname);
 130
 131                         return false;
 132                 } else {
 133                         ifdebug(PROTOCOL) {
 134                                 ifdebug(META)
 135                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 136                                                    request_name[reqno], c->name, c->hostname, request);
 137                                 else
 138                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 139                                                    request_name[reqno], c->name, c->hostname);
 140                         }
 141                 }
 142
 143                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 144                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 145                                    c->hostname);
 146                         return false;
 147                 }
 148
 149                 if(!request_handlers[reqno](c, request)) {
 150                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 151
 152                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 153                                    request_name[reqno], c->name, c->hostname);
 154                         return false;
 155                 }
 156         } else {
 157                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 158                            c->name, c->hostname);
 159                 return false;
 160         }
 161
 162         return true;
 163 }
 164
 165 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 166         return strcmp(a->request, b->request);
 167 }
 168
 169 static void free_past_request(past_request_t *r) {
 170         if(r->request)
 171                 free(r->request);
 172
 173         free(r);
 174 }
 175
 176 static struct event past_request_event;
 177
 178 bool seen_request(char *request) {
 179         past_request_t *new, p = {0};
 180
 181         p.request = request;
 182
 183         if(splay_search(past_request_tree, &p)) {
 184                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 185                 return true;
 186         } else {
 187                 new = xmalloc(sizeof *new);
 188                 new->request = xstrdup(request);
 189                 new->firstseen = time(NULL);
 190                 splay_insert(past_request_tree, new);
 191                 event_add(&past_request_event, &(struct timeval){10, 0});
 192                 return false;
 193         }
 194 }
 195
 196 void age_past_requests(int fd, short events, void *data) {
 197         splay_node_t *node, *next;
 198         past_request_t *p;
 199         int left = 0, deleted = 0;
 200         time_t now = time(NULL);
 201
 202         for(node = past_request_tree->head; node; node = next) {
 203                 next = node->next;
 204                 p = node->data;
 205
 206                 if(p->firstseen + pinginterval < now)
 207                         splay_delete_node(past_request_tree, node), deleted++;
 208                 else
 209                         left++;
 210         }
 211
 212         if(left || deleted)
 213                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 214                            deleted, left);
 215
 216         if(left)
 217                 event_add(&past_request_event, &(struct timeval){10, 0});
 218 }
 219
 220 void init_requests(void) {
 221         past_request_tree = splay_alloc_tree((splay_compare_t) past_request_compare, (splay_action_t) free_past_request);
 222
 223         timeout_set(&past_request_event, age_past_requests, NULL);
 224 }
 225
 226 void exit_requests(void) {
 227         splay_delete_tree(past_request_tree);
 228
 229         event_del(&past_request_event);
 230 }