www.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                   2000-2016 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 *) = {
  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,
  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",
  53 };
  54
  55 static avl_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 buffer[MAXBUFSIZE];
  71         int len, request = 0;
  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(buffer, sizeof buffer, format, args);
  79         buffer[sizeof buffer - 1] = 0;
  80         va_end(args);
  81
  82         if(len < 0 || len > sizeof buffer - 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 == everyone) {
 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         ifdebug(PROTOCOL) {
 111                 sscanf(from->buffer, "%d", &request);
 112                 ifdebug(META)
 113                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 114                                    request_name[request], from->name, from->hostname,
 115                                    from->buffer);
 116                 else
 117                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 118                                    request_name[request], from->name, from->hostname);
 119         }
 120
 121         from->buffer[from->reqlen - 1] = '\n';
 122
 123         broadcast_meta(from, from->buffer, from->reqlen);
 124 }
 125
 126 bool receive_request(connection_t *c) {
 127         int request;
 128
 129         if(sscanf(c->buffer, "%d", &request) == 1) {
 130                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 131                         ifdebug(META)
 132                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 133                                            c->name, c->hostname, c->buffer);
 134                         else
 135                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 136                                            c->name, c->hostname);
 137
 138                         return false;
 139                 } else {
 140                         ifdebug(PROTOCOL) {
 141                                 ifdebug(META)
 142                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 143                                                    request_name[request], c->name, c->hostname,
 144                                                    c->buffer);
 145                                 else
 146                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 147                                                    request_name[request], c->name, c->hostname);
 148                         }
 149                 }
 150
 151                 if((c->allow_request != ALL) && (c->allow_request != request)) {
 152                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 153                                    c->hostname);
 154                         return false;
 155                 }
 156
 157                 if(!request_handlers[request](c)) {
 158                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 159
 160                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 161                                    request_name[request], c->name, c->hostname);
 162                         return false;
 163                 }
 164         } else {
 165                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 166                            c->name, c->hostname);
 167                 return false;
 168         }
 169
 170         return true;
 171 }
 172
 173 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 174         return strcmp(a->request, b->request);
 175 }
 176
 177 static void free_past_request(past_request_t *r) {
 178         if(r->request)
 179                 free(r->request);
 180
 181         free(r);
 182 }
 183
 184 void init_requests(void) {
 185         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 186 }
 187
 188 void exit_requests(void) {
 189         avl_delete_tree(past_request_tree);
 190 }
 191
 192 bool seen_request(char *request) {
 193         past_request_t *new, p = {NULL};
 194
 195         p.request = request;
 196
 197         if(avl_search(past_request_tree, &p)) {
 198                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 199                 return true;
 200         } else {
 201                 new = xmalloc(sizeof(*new));
 202                 new->request = xstrdup(request);
 203                 new->firstseen = now;
 204                 avl_insert(past_request_tree, new);
 205                 return false;
 206         }
 207 }
 208
 209 void age_past_requests(void) {
 210         avl_node_t *node, *next;
 211         past_request_t *p;
 212         int left = 0, deleted = 0;
 213
 214         for(node = past_request_tree->head; node; node = next) {
 215                 next = node->next;
 216                 p = node->data;
 217
 218                 if(p->firstseen + pinginterval <= now)
 219                         avl_delete_node(past_request_tree, node), deleted++;
 220                 else
 221                         left++;
 222         }
 223
 224         if(left || deleted)
 225                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 226                            deleted, left);
 227 }