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                   2000-2022 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 "crypto.h"
  26 #include "logger.h"
  27 #include "meta.h"
  28 #include "protocol.h"
  29 #include "utils.h"
  30 #include "xalloc.h"
  31
  32 bool tunnelserver = false;
  33 bool strictsubnets = false;
  34 bool experimental = true;
  35
  36 static inline bool is_valid_request(request_t req) {
  37         return req > ALL && req < LAST;
  38 }
  39
  40 /* Request handlers */
  41 const request_entry_t *get_request_entry(request_t req) {
  42         if(!is_valid_request(req)) {
  43                 logger(DEBUG_ALWAYS, LOG_ERR, "Invalid request %d", req);
  44                 return NULL;
  45         }
  46
  47         // Prevent user from accessing the table directly to always have bound checks
  48         static const request_entry_t request_entries[] = {
  49                 [ID] = {id_h, "ID"},
  50                 [METAKEY] = {metakey_h, "METAKEY"},
  51                 [CHALLENGE] = {challenge_h, "CHALLENGE"},
  52                 [CHAL_REPLY] = {chal_reply_h, "CHAL_REPLY"},
  53                 [ACK] = {ack_h, "ACK"},
  54                 [STATUS] = {NULL, "STATUS"},
  55                 [ERROR] = {NULL, "ERROR"},
  56                 [TERMREQ] = {termreq_h, "TERMREQ"},
  57                 [PING] = {ping_h, "PING"},
  58                 [PONG] = {pong_h, "PONG"},
  59                 [ADD_SUBNET] = {add_subnet_h, "ADD_SUBNET"},
  60                 [DEL_SUBNET] = {del_subnet_h, "DEL_SUBNET"},
  61                 [ADD_EDGE] = {add_edge_h, "ADD_EDGE"},
  62                 [DEL_EDGE] = {del_edge_h, "DEL_EDGE"},
  63                 [KEY_CHANGED] = {key_changed_h, "KEY_CHANGED"},
  64                 [REQ_KEY] = {req_key_h, "REQ_KEY"},
  65                 [ANS_KEY] = {ans_key_h, "ANS_KEY"},
  66                 [PACKET] = {tcppacket_h, "PACKET"},
  67                 [CONTROL] = {control_h, "CONTROL"},
  68                 /* Not "real" requests yet */
  69                 [REQ_PUBKEY] = {NULL, "REQ_PUBKEY"},
  70                 [ANS_PUBKEY] = {NULL, "ANS_PUBKEY"},
  71                 [SPTPS_PACKET] = {sptps_tcppacket_h, "SPTPS_PACKET"},
  72                 [UDP_INFO] = {udp_info_h, "UDP_INFO"},
  73                 [MTU_INFO] = {mtu_info_h, "MTU_INFO"},
  74         };
  75         return &request_entries[req];
  76 }
  77
  78 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
  79         return strcmp(a->request, b->request);
  80 }
  81
  82 static void free_past_request(past_request_t *r) {
  83         free((char *)r->request);
  84         free(r);
  85 }
  86
  87 static splay_tree_t past_request_tree = {
  88         .compare = (splay_compare_t) past_request_compare,
  89         .delete = (splay_action_t) free_past_request,
  90 };
  91
  92 /* Generic request routines - takes care of logging and error
  93    detection as well */
  94
  95 bool send_request(connection_t *c, const char *format, ...) {
  96         va_list args;
  97         char request[MAXBUFSIZE];
  98         int len;
  99
 100         /* Use vsnprintf instead of vxasprintf: faster, no memory
 101            fragmentation, cleanup is automatic, and there is a limit on the
 102            input buffer anyway */
 103
 104         va_start(args, format);
 105         len = vsnprintf(request, sizeof(request), format, args);
 106         request[sizeof(request) - 1] = 0;
 107         va_end(args);
 108
 109         if(len < 0 || (size_t)len > sizeof(request) - 1) {
 110                 logger(DEBUG_ALWAYS, LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
 111                        c->name, c->hostname);
 112                 return false;
 113         }
 114
 115         int id = atoi(request);
 116         logger(DEBUG_META, LOG_DEBUG, "Sending %s to %s (%s): %s", get_request_entry(id)->name, c->name, c->hostname, request);
 117
 118         request[len++] = '\n';
 119
 120         if(c == everyone) {
 121                 broadcast_meta(NULL, request, len);
 122                 return true;
 123         } else {
 124                 if(id) {
 125                         return send_meta(c, request, len);
 126                 } else {
 127                         send_meta_raw(c, request, len);
 128                         return true;
 129                 }
 130         }
 131 }
 132
 133 void forward_request(connection_t *from, const char *request) {
 134         logger(DEBUG_META, LOG_DEBUG, "Forwarding %s from %s (%s): %s", get_request_entry(atoi(request))->name, from->name, from->hostname, request);
 135
 136         // Create a temporary newline-terminated copy of the request
 137         size_t len = strlen(request);
 138         const size_t tmplen = len + 1;
 139         char *tmp = alloca(tmplen);
 140         memcpy(tmp, request, len);
 141         tmp[len] = '\n';
 142         broadcast_meta(from, tmp, tmplen);
 143 }
 144
 145 bool receive_request(connection_t *c, const char *request) {
 146         if(c->outgoing && proxytype == PROXY_HTTP && c->allow_request == ID) {
 147                 if(!request[0] || request[0] == '\r') {
 148                         return true;
 149                 }
 150
 151                 if(!strncasecmp(request, "HTTP/1.1 ", 9)) {
 152                         if(!strncmp(request + 9, "200", 3)) {
 153                                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Proxy request granted");
 154                                 return true;
 155                         } else {
 156                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Proxy request rejected: %s", request + 9);
 157                                 return false;
 158                         }
 159                 }
 160         }
 161
 162         int reqno = atoi(request);
 163
 164         if(reqno || *request == '0') {
 165                 if(!is_valid_request(reqno) || !get_request_entry(reqno)->handler) {
 166                         logger(DEBUG_META, LOG_DEBUG, "Unknown request from %s (%s): %s", c->name, c->hostname, request);
 167                         return false;
 168                 }
 169
 170                 const request_entry_t *entry = get_request_entry(reqno);
 171                 logger(DEBUG_META, LOG_DEBUG, "Got %s from %s (%s): %s", entry->name, c->name, c->hostname, request);
 172
 173                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 174                         logger(DEBUG_ALWAYS, LOG_ERR, "Unauthorized request from %s (%s)", c->name, c->hostname);
 175                         return false;
 176                 }
 177
 178                 if(!entry->handler(c, request)) {
 179                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 180
 181                         if(reqno != TERMREQ) {
 182                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while processing %s from %s (%s)", entry->name, c->name, c->hostname);
 183                         }
 184
 185                         return false;
 186                 }
 187         } else {
 188                 logger(DEBUG_ALWAYS, LOG_ERR, "Bogus data received from %s (%s)", c->name, c->hostname);
 189                 return false;
 190         }
 191
 192         return true;
 193 }
 194
 195 static timeout_t past_request_timeout;
 196
 197 static void age_past_requests(void *data) {
 198         (void)data;
 199         int left = 0, deleted = 0;
 200
 201         for splay_each(past_request_t, p, &past_request_tree) {
 202                 if(p->firstseen + pinginterval <= now.tv_sec) {
 203                         splay_delete_node(&past_request_tree, node), deleted++;
 204                 } else {
 205                         left++;
 206                 }
 207         }
 208
 209         if(left || deleted) {
 210                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Aging past requests: deleted %d, left %d", deleted, left);
 211         }
 212
 213         if(left)
 214                 timeout_set(&past_request_timeout, &(struct timeval) {
 215                 10, jitter()
 216         });
 217 }
 218
 219 bool seen_request(const char *request) {
 220         past_request_t *new, p = {0};
 221
 222         p.request = request;
 223
 224         if(splay_search(&past_request_tree, &p)) {
 225                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Already seen request");
 226                 return true;
 227         } else {
 228                 new = xmalloc(sizeof(*new));
 229                 new->request = xstrdup(request);
 230                 new->firstseen = now.tv_sec;
 231                 splay_insert(&past_request_tree, new);
 232                 timeout_add(&past_request_timeout, age_past_requests, NULL, &(struct timeval) {
 233                         10, jitter()
 234                 });
 235                 return false;
 236         }
 237 }
 238
 239 void exit_requests(void) {
 240         splay_empty_tree(&past_request_tree);
 241
 242         timeout_del(&past_request_timeout);
 243 }