git.meshlink.io Git - meshlink/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         /* Note: request is not zero terminated anymore after a call to this function! */
 107         ifdebug(PROTOCOL) {
 108                 ifdebug(META)
 109                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 110                                    request_name[atoi(request)], from->name, from->hostname, request);
 111                 else
 112                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 113                                    request_name[atoi(request)], from->name, from->hostname);
 114         }
 115
 116         int len = strlen(request);
 117         request[len++] = '\n';
 118         broadcast_meta(from, request, len);
 119 }
 120
 121 bool receive_request(connection_t *c, char *request) {
 122         int reqno = atoi(request);
 123
 124         if(reqno || *request == '0') {
 125                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
 126                         ifdebug(META)
 127                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 128                                            c->name, c->hostname, request);
 129                         else
 130                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 131                                            c->name, c->hostname);
 132
 133                         return false;
 134                 } else {
 135                         ifdebug(PROTOCOL) {
 136                                 ifdebug(META)
 137                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 138                                                    request_name[reqno], c->name, c->hostname, request);
 139                                 else
 140                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 141                                                    request_name[reqno], c->name, c->hostname);
 142                         }
 143                 }
 144
 145                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 146                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 147                                    c->hostname);
 148                         return false;
 149                 }
 150
 151                 if(!request_handlers[reqno](c, request)) {
 152                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 153
 154                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 155                                    request_name[reqno], c->name, c->hostname);
 156                         return false;
 157                 }
 158         } else {
 159                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 160                            c->name, c->hostname);
 161                 return false;
 162         }
 163
 164         return true;
 165 }
 166
 167 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 168         return strcmp(a->request, b->request);
 169 }
 170
 171 static void free_past_request(past_request_t *r) {
 172         if(r->request)
 173                 free(r->request);
 174
 175         free(r);
 176 }
 177
 178 static struct event past_request_event;
 179
 180 bool seen_request(char *request) {
 181         past_request_t *new, p = {NULL};
 182
 183         p.request = request;
 184
 185         if(splay_search(past_request_tree, &p)) {
 186                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 187                 return true;
 188         } else {
 189                 new = xmalloc(sizeof *new);
 190                 new->request = xstrdup(request);
 191                 new->firstseen = time(NULL);
 192                 splay_insert(past_request_tree, new);
 193                 event_add(&past_request_event, &(struct timeval){10, 0});
 194                 return false;
 195         }
 196 }
 197
 198 static void age_past_requests(int fd, short events, void *data) {
 199         splay_node_t *node, *next;
 200         past_request_t *p;
 201         int left = 0, deleted = 0;
 202         time_t now = time(NULL);
 203
 204         for(node = past_request_tree->head; node; node = next) {
 205                 next = node->next;
 206                 p = node->data;
 207
 208                 if(p->firstseen + pinginterval <= now)
 209                         splay_delete_node(past_request_tree, node), deleted++;
 210                 else
 211                         left++;
 212         }
 213
 214         if(left || deleted)
 215                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 216                            deleted, left);
 217
 218         if(left)
 219                 event_add(&past_request_event, &(struct timeval){10, 0});
 220 }
 221
 222 void init_requests(void) {
 223         past_request_tree = splay_alloc_tree((splay_compare_t) past_request_compare, (splay_action_t) free_past_request);
 224
 225         timeout_set(&past_request_event, age_past_requests, NULL);
 226 }
 227
 228 void exit_requests(void) {
 229         splay_delete_tree(past_request_tree);
 230
 231         if(timeout_initialized(&past_request_event))
 232                 event_del(&past_request_event);
 233 }