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                   2000-2013 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 = true;
  34
  35 /* Jumptable for the request handlers */
  36
  37 static bool (*request_handlers[])(connection_t *, const 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                 NULL, NULL, /* Not "real" requests (yet) */
  45                 sptps_tcppacket_h,
  46                 udp_info_h, mtu_info_h,
  47 };
  48
  49 /* Request names */
  50
  51 static char (*request_name[]) = {
  52                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
  53                 "STATUS", "ERROR", "TERMREQ",
  54                 "PING", "PONG",
  55                 "ADD_SUBNET", "DEL_SUBNET",
  56                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET", "CONTROL",
  57                 "REQ_PUBKEY", "ANS_PUBKEY", "SPTPS_PACKET", "UDP_INFO", "MTU_INFO",
  58 };
  59
  60 static splay_tree_t *past_request_tree;
  61
  62 /* Generic request routines - takes care of logging and error
  63    detection as well */
  64
  65 bool send_request(connection_t *c, const char *format, ...) {
  66         va_list args;
  67         char request[MAXBUFSIZE];
  68         int len;
  69
  70         /* Use vsnprintf instead of vxasprintf: faster, no memory
  71            fragmentation, cleanup is automatic, and there is a limit on the
  72            input buffer anyway */
  73
  74         va_start(args, format);
  75         len = vsnprintf(request, MAXBUFSIZE, format, args);
  76         va_end(args);
  77
  78         if(len < 0 || len > MAXBUFSIZE - 1) {
  79                 logger(DEBUG_ALWAYS, LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
  80                            c->name, c->hostname);
  81                 return false;
  82         }
  83
  84         logger(DEBUG_META, LOG_DEBUG, "Sending %s to %s (%s): %s", request_name[atoi(request)], c->name, c->hostname, request);
  85
  86         request[len++] = '\n';
  87
  88         if(c == everyone) {
  89                 broadcast_meta(NULL, request, len);
  90                 return true;
  91         } else
  92                 return send_meta(c, request, len);
  93 }
  94
  95 void forward_request(connection_t *from, const char *request) {
  96         logger(DEBUG_META, LOG_DEBUG, "Forwarding %s from %s (%s): %s", request_name[atoi(request)], from->name, from->hostname, request);
  97
  98         // Create a temporary newline-terminated copy of the request
  99         int len = strlen(request);
 100         char tmp[len + 1];
 101         memcpy(tmp, request, len);
 102         tmp[len] = '\n';
 103         broadcast_meta(from, tmp, sizeof tmp);
 104 }
 105
 106 bool receive_request(connection_t *c, const char *request) {
 107         if(c->outgoing && proxytype == PROXY_HTTP && c->allow_request == ID) {
 108                 if(!request[0] || request[0] == '\r')
 109                         return true;
 110                 if(!strncasecmp(request, "HTTP/1.1 ", 9)) {
 111                         if(!strncmp(request + 9, "200", 3)) {
 112                                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Proxy request granted");
 113                                 return true;
 114                         } else {
 115                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Proxy request rejected: %s", request + 9);
 116                                 return false;
 117                         }
 118                 }
 119         }
 120
 121         int reqno = atoi(request);
 122
 123         if(reqno || *request == '0') {
 124                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
 125                         logger(DEBUG_META, LOG_DEBUG, "Unknown request from %s (%s): %s", c->name, c->hostname, request);
 126                         return false;
 127                 } else {
 128                         logger(DEBUG_META, LOG_DEBUG, "Got %s from %s (%s): %s", request_name[reqno], c->name, c->hostname, request);
 129                 }
 130
 131                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 132                         logger(DEBUG_ALWAYS, LOG_ERR, "Unauthorized request from %s (%s)", c->name, c->hostname);
 133                         return false;
 134                 }
 135
 136                 if(!request_handlers[reqno](c, request)) {
 137                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 138
 139                         if(reqno != TERMREQ)
 140                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while processing %s from %s (%s)", request_name[reqno], c->name, c->hostname);
 141                         return false;
 142                 }
 143         } else {
 144                 logger(DEBUG_ALWAYS, LOG_ERR, "Bogus data received from %s (%s)", c->name, c->hostname);
 145                 return false;
 146         }
 147
 148         return true;
 149 }
 150
 151 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
 152         return strcmp(a->request, b->request);
 153 }
 154
 155 static void free_past_request(past_request_t *r) {
 156         if(r->request)
 157                 free((char *)r->request);
 158
 159         free(r);
 160 }
 161
 162 static timeout_t past_request_timeout;
 163
 164 static void age_past_requests(void *data) {
 165         int left = 0, deleted = 0;
 166
 167         for splay_each(past_request_t, p, past_request_tree) {
 168                 if(p->firstseen + pinginterval <= now.tv_sec)
 169                         splay_delete_node(past_request_tree, node), deleted++;
 170                 else
 171                         left++;
 172         }
 173
 174         if(left || deleted)
 175                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Aging past requests: deleted %d, left %d", deleted, left);
 176
 177         if(left)
 178                 timeout_set(&past_request_timeout, &(struct timeval){10, rand() % 100000});
 179 }
 180
 181 bool seen_request(const char *request) {
 182         past_request_t *new, p = {NULL};
 183
 184         p.request = request;
 185
 186         if(splay_search(past_request_tree, &p)) {
 187                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Already seen request");
 188                 return true;
 189         } else {
 190                 new = xmalloc(sizeof *new);
 191                 new->request = xstrdup(request);
 192                 new->firstseen = now.tv_sec;
 193                 splay_insert(past_request_tree, new);
 194                 timeout_add(&past_request_timeout, age_past_requests, NULL, &(struct timeval){10, rand() % 100000});
 195                 return false;
 196         }
 197 }
 198
 199 void init_requests(void) {
 200         past_request_tree = splay_alloc_tree((splay_compare_t) past_request_compare, (splay_action_t) free_past_request);
 201 }
 202
 203 void exit_requests(void) {
 204         splay_delete_tree(past_request_tree);
 205
 206         timeout_del(&past_request_timeout);
 207 }