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 bool experimental = false;
  34
  35 /* Jumptable for the request handlers */
  36
  37 static bool (*request_handlers[])(connection_t *, char *) = {
  38                 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
  39                 status_h, error_h, termreq_h,
  40                 ping_h, pong_h,
  41                 add_subnet_h, del_subnet_h,
  42                 add_edge_h, del_edge_h,
  43                 key_changed_h, req_key_h, ans_key_h, tcppacket_h, control_h,
  44 };
  45
  46 /* Request names */
  47
  48 static char (*request_name[]) = {
  49                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
  50                 "STATUS", "ERROR", "TERMREQ",
  51                 "PING", "PONG",
  52                 "ADD_SUBNET", "DEL_SUBNET",
  53                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET", "CONTROL",
  54 };
  55
  56 static splay_tree_t *past_request_tree;
  57
  58 bool check_id(const char *id) {
  59         for(; *id; id++)
  60                 if(!isalnum(*id) && *id != '_')
  61                         return false;
  62
  63         return true;
  64 }
  65
  66 /* Generic request routines - takes care of logging and error
  67    detection as well */
  68
  69 bool send_request(connection_t *c, const char *format, ...) {
  70         va_list args;
  71         char request[MAXBUFSIZE];
  72         int len;
  73
  74         /* Use vsnprintf instead of vxasprintf: faster, no memory
  75            fragmentation, cleanup is automatic, and there is a limit on the
  76            input buffer anyway */
  77
  78         va_start(args, format);
  79         len = vsnprintf(request, MAXBUFSIZE, format, args);
  80         va_end(args);
  81
  82         if(len < 0 || len > MAXBUFSIZE - 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                 ifdebug(META)
  90                         logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
  91                                    request_name[atoi(request)], c->name, c->hostname, request);
  92                 else
  93                         logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[atoi(request)],
  94                                    c->name, c->hostname);
  95         }
  96
  97         request[len++] = '\n';
  98
  99         if(c == everyone) {
 100                 broadcast_meta(NULL, request, len);
 101                 return true;
 102         } else
 103                 return send_meta(c, request, len);
 104 }
 105
 106 void forward_request(connection_t *from, char *request) {
 107         /* Note: request is not zero terminated anymore after a call to this function! */
 108         ifdebug(PROTOCOL) {
 109                 ifdebug(META)
 110                         logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
 111                                    request_name[atoi(request)], from->name, from->hostname, request);
 112                 else
 113                         logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
 114                                    request_name[atoi(request)], from->name, from->hostname);
 115         }
 116
 117         int len = strlen(request);
 118         request[len++] = '\n';
 119         broadcast_meta(from, request, len);
 120 }
 121
 122 bool receive_request(connection_t *c, char *request) {
 123         int reqno = atoi(request);
 124
 125         if(reqno || *request == '0') {
 126                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
 127                         ifdebug(META)
 128                                 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
 129                                            c->name, c->hostname, request);
 130                         else
 131                                 logger(LOG_ERR, "Unknown request from %s (%s)",
 132                                            c->name, c->hostname);
 133
 134                         return false;
 135                 } else {
 136                         ifdebug(PROTOCOL) {
 137                                 ifdebug(META)
 138                                         logger(LOG_DEBUG, "Got %s from %s (%s): %s",
 139                                                    request_name[reqno], c->name, c->hostname, request);
 140                                 else
 141                                         logger(LOG_DEBUG, "Got %s from %s (%s)",
 142                                                    request_name[reqno], c->name, c->hostname);
 143                         }
 144                 }
 145
 146                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 147                         logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
 148                                    c->hostname);
 149                         return false;
 150                 }
 151
 152                 if(!request_handlers[reqno](c, request)) {
 153                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 154
 155                         logger(LOG_ERR, "Error while processing %s from %s (%s)",
 156                                    request_name[reqno], c->name, c->hostname);
 157                         return false;
 158                 }
 159         } else {
 160                 logger(LOG_ERR, "Bogus data received from %s (%s)",
 161                            c->name, c->hostname);
 162                 return false;
 163         }
 164
 165         return true;
 166 }
 167
 168 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 169         return strcmp(a->request, b->request);
 170 }
 171
 172 static void free_past_request(past_request_t *r) {
 173         if(r->request)
 174                 free(r->request);
 175
 176         free(r);
 177 }
 178
 179 static struct event past_request_event;
 180
 181 bool seen_request(char *request) {
 182         past_request_t *new, p = {NULL};
 183
 184         p.request = request;
 185
 186         if(splay_search(past_request_tree, &p)) {
 187                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
 188                 return true;
 189         } else {
 190                 new = xmalloc(sizeof *new);
 191                 new->request = xstrdup(request);
 192                 new->firstseen = time(NULL);
 193                 splay_insert(past_request_tree, new);
 194                 event_add(&past_request_event, &(struct timeval){10, 0});
 195                 return false;
 196         }
 197 }
 198
 199 static void age_past_requests(int fd, short events, void *data) {
 200         splay_node_t *node, *next;
 201         past_request_t *p;
 202         int left = 0, deleted = 0;
 203         time_t now = time(NULL);
 204
 205         for(node = past_request_tree->head; node; node = next) {
 206                 next = node->next;
 207                 p = node->data;
 208
 209                 if(p->firstseen + pinginterval <= now)
 210                         splay_delete_node(past_request_tree, node), deleted++;
 211                 else
 212                         left++;
 213         }
 214
 215         if(left || deleted)
 216                 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
 217                            deleted, left);
 218
 219         if(left)
 220                 event_add(&past_request_event, &(struct timeval){10, 0});
 221 }
 222
 223 void init_requests(void) {
 224         past_request_tree = splay_alloc_tree((splay_compare_t) past_request_compare, (splay_action_t) free_past_request);
 225
 226         timeout_set(&past_request_event, age_past_requests, NULL);
 227 }
 228
 229 void exit_requests(void) {
 230         splay_delete_tree(past_request_tree);
 231
 232         if(timeout_initialized(&past_request_event))
 233                 event_del(&past_request_event);
 234 }