tinc-vpn.org Git - tinc/blob - src/protocol.c

   1 /*
   2     protocol.c -- handle the meta-protocol, basic functions
   3     Copyright (C) 1999-2001 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000,2001 Guus Sliepen <guus@sliepen.eu.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
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id: protocol.c,v 1.28.4.136 2002/09/09 21:24:41 guus Exp $
  21 */
  22
  23 #include "config.h"
  24
  25 #include <sys/types.h>
  26
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <syslog.h>
  30 #include <stdio.h>
  31 #include <stdarg.h>
  32 #include <errno.h>
  33
  34 #include <utils.h>
  35 #include <xalloc.h>
  36
  37 #include "conf.h"
  38 #include "protocol.h"
  39 #include "meta.h"
  40 #include "connection.h"
  41
  42 #include "system.h"
  43
  44 avl_tree_t *past_request_tree;
  45
  46 int check_id(char *id)
  47 {
  48         int i;
  49
  50         for(i = 0; i < strlen(id); i++)
  51                 if(!isalnum(id[i]) && id[i] != '_')
  52                         return -1;
  53
  54         return 0;
  55 }
  56
  57 /* Generic request routines - takes care of logging and error
  58    detection as well */
  59
  60 int send_request(connection_t * c, const char *format, ...)
  61 {
  62         va_list args;
  63         char buffer[MAXBUFSIZE];
  64         int len, request;
  65
  66         cp();
  67
  68         /* Use vsnprintf instead of vasprintf: faster, no memory
  69            fragmentation, cleanup is automatic, and there is a limit on the
  70            input buffer anyway */
  71
  72         va_start(args, format);
  73         len = vsnprintf(buffer, MAXBUFSIZE, format, args);
  74         va_end(args);
  75
  76         if(len < 0 || len > MAXBUFSIZE - 1) {
  77                 syslog(LOG_ERR, _("Output buffer overflow while sending request to %s (%s)"),
  78                            c->name, c->hostname);
  79                 return -1;
  80         }
  81
  82         if(debug_lvl >= DEBUG_PROTOCOL) {
  83                 sscanf(buffer, "%d", &request);
  84                 if(debug_lvl >= DEBUG_META)
  85                         syslog(LOG_DEBUG, _("Sending %s to %s (%s): %s"),
  86                                    request_name[request], c->name, c->hostname, buffer);
  87                 else
  88                         syslog(LOG_DEBUG, _("Sending %s to %s (%s)"), request_name[request],
  89                                    c->name, c->hostname);
  90         }
  91
  92         buffer[len++] = '\n';
  93
  94         if(c == broadcast)
  95                 return broadcast_meta(NULL, buffer, len);
  96         else
  97                 return send_meta(c, buffer, len);
  98 }
  99
 100 int forward_request(connection_t * from)
 101 {
 102         int request;
 103         cp();
 104
 105         cp();
 106
 107         if(debug_lvl >= DEBUG_PROTOCOL) {
 108                 sscanf(from->buffer, "%d", &request);
 109                 if(debug_lvl >= DEBUG_META)
 110                         syslog(LOG_DEBUG, _("Forwarding %s from %s (%s): %s"),
 111                                    request_name[request], from->name, from->hostname,
 112                                    from->buffer);
 113                 else
 114                         syslog(LOG_DEBUG, _("Forwarding %s from %s (%s)"),
 115                                    request_name[request], from->name, from->hostname);
 116         }
 117
 118         from->buffer[from->reqlen - 1] = '\n';
 119
 120         return broadcast_meta(from, from->buffer, from->reqlen);
 121 }
 122
 123 int receive_request(connection_t * c)
 124 {
 125         int request;
 126
 127         cp();
 128
 129         if(sscanf(c->buffer, "%d", &request) == 1) {
 130                 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
 131                         if(debug_lvl >= DEBUG_META)
 132                                 syslog(LOG_DEBUG, _("Unknown request from %s (%s): %s"),
 133                                            c->name, c->hostname, c->buffer);
 134                         else
 135                                 syslog(LOG_ERR, _("Unknown request from %s (%s)"),
 136                                            c->name, c->hostname);
 137
 138                         return -1;
 139                 } else {
 140                         if(debug_lvl >= DEBUG_PROTOCOL) {
 141                                 if(debug_lvl >= DEBUG_META)
 142                                         syslog(LOG_DEBUG, _("Got %s from %s (%s): %s"),
 143                                                    request_name[request], c->name, c->hostname,
 144                                                    c->buffer);
 145                                 else
 146                                         syslog(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                         syslog(LOG_ERR, _("Unauthorized request from %s (%s)"), c->name,
 153                                    c->hostname);
 154                         return -1;
 155                 }
 156
 157                 if(request_handlers[request] (c))
 158                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 159                 {
 160                         syslog(LOG_ERR, _("Error while processing %s from %s (%s)"),
 161                                    request_name[request], c->name, c->hostname);
 162                         return -1;
 163                 }
 164         } else {
 165                 syslog(LOG_ERR, _("Bogus data received from %s (%s)"),
 166                            c->name, c->hostname);
 167                 return -1;
 168         }
 169
 170         return 0;
 171 }
 172
 173 int past_request_compare(past_request_t * a, past_request_t * b)
 174 {
 175         return strcmp(a->request, b->request);
 176 }
 177
 178 void free_past_request(past_request_t * r)
 179 {
 180         cp();
 181
 182         if(r->request)
 183                 free(r->request);
 184
 185         free(r);
 186 }
 187
 188 void init_requests(void)
 189 {
 190         cp();
 191
 192         past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
 193 }
 194
 195 void exit_requests(void)
 196 {
 197         cp();
 198
 199         avl_delete_tree(past_request_tree);
 200 }
 201
 202 int seen_request(char *request)
 203 {
 204         past_request_t p, *new;
 205
 206         cp();
 207
 208         p.request = request;
 209
 210         if(avl_search(past_request_tree, &p)) {
 211                 if(debug_lvl >= DEBUG_SCARY_THINGS)
 212                         syslog(LOG_DEBUG, _("Already seen request"));
 213                 return 1;
 214         } else {
 215                 new = (past_request_t *) xmalloc(sizeof(*new));
 216                 new->request = xstrdup(request);
 217                 new->firstseen = now;
 218                 avl_insert(past_request_tree, new);
 219                 return 0;
 220         }
 221 }
 222
 223 void age_past_requests(void)
 224 {
 225         avl_node_t *node, *next;
 226         past_request_t *p;
 227         int left = 0, deleted = 0;
 228
 229         cp();
 230
 231         for(node = past_request_tree->head; node; node = next) {
 232                 next = node->next;
 233                 p = (past_request_t *) node->data;
 234
 235                 if(p->firstseen + pingtimeout < now)
 236                         avl_delete_node(past_request_tree, node), deleted++;
 237                 else
 238                         left++;
 239         }
 240
 241         if(debug_lvl >= DEBUG_SCARY_THINGS && left + deleted)
 242                 syslog(LOG_DEBUG, _("Aging past requests: deleted %d, left %d\n"),
 243                            deleted, left);
 244 }
 245
 246 /* Jumptable for the request handlers */
 247
 248 int (*request_handlers[]) (connection_t *) = {
 249                 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
 250                 status_h, error_h, termreq_h,
 251                 ping_h, pong_h,
 252                 add_subnet_h, del_subnet_h,
 253                 add_edge_h, del_edge_h,
 254                 key_changed_h, req_key_h, ans_key_h, tcppacket_h,
 255 };
 256
 257 /* Request names */
 258
 259 char (*request_name[]) = {
 260                 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
 261                 "STATUS", "ERROR", "TERMREQ",
 262                 "PING", "PONG",
 263                 "ADD_SUBNET", "DEL_SUBNET",
 264                 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET",
 265 };