git.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         if(r) {
  84                 free((char *)r->request);
  85                 free(r);
  86         }
  87 }
  88
  89 static splay_tree_t past_request_tree = {
  90         .compare = (splay_compare_t) past_request_compare,
  91         .delete = (splay_action_t) free_past_request,
  92 };
  93
  94 /* Generic request routines - takes care of logging and error
  95    detection as well */
  96
  97 bool send_request(connection_t *c, const char *format, ...) {
  98         va_list args;
  99         char request[MAXBUFSIZE];
 100         int len;
 101
 102         /* Use vsnprintf instead of vxasprintf: faster, no memory
 103            fragmentation, cleanup is automatic, and there is a limit on the
 104            input buffer anyway */
 105
 106         va_start(args, format);
 107         len = vsnprintf(request, sizeof(request), format, args);
 108         request[sizeof(request) - 1] = 0;
 109         va_end(args);
 110
 111         if(len < 0 || (size_t)len > sizeof(request) - 1) {
 112                 logger(DEBUG_ALWAYS, LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
 113                        c->name, c->hostname);
 114                 return false;
 115         }
 116
 117         int id = atoi(request);
 118         logger(DEBUG_META, LOG_DEBUG, "Sending %s to %s (%s): %s", get_request_entry(id)->name, c->name, c->hostname, request);
 119
 120         request[len++] = '\n';
 121
 122         if(c == everyone) {
 123                 broadcast_meta(NULL, request, len);
 124                 return true;
 125         } else {
 126                 if(id) {
 127                         return send_meta(c, request, len);
 128                 } else {
 129                         send_meta_raw(c, request, len);
 130                         return true;
 131                 }
 132         }
 133 }
 134
 135 void forward_request(connection_t *from, const char *request) {
 136         logger(DEBUG_META, LOG_DEBUG, "Forwarding %s from %s (%s): %s", get_request_entry(atoi(request))->name, from->name, from->hostname, request);
 137
 138         // Create a temporary newline-terminated copy of the request
 139         size_t len = strlen(request);
 140         const size_t tmplen = len + 1;
 141         char *tmp = alloca(tmplen);
 142         memcpy(tmp, request, len);
 143         tmp[len] = '\n';
 144         broadcast_meta(from, tmp, tmplen);
 145 }
 146
 147 bool receive_request(connection_t *c, const char *request) {
 148         if(c->outgoing && proxytype == PROXY_HTTP && c->allow_request == ID) {
 149                 if(!request[0] || request[0] == '\r') {
 150                         return true;
 151                 }
 152
 153                 if(!strncasecmp(request, "HTTP/1.1 ", 9)) {
 154                         if(!strncmp(request + 9, "200", 3)) {
 155                                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Proxy request granted");
 156                                 return true;
 157                         } else {
 158                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Proxy request rejected: %s", request + 9);
 159                                 return false;
 160                         }
 161                 }
 162         }
 163
 164         int reqno = atoi(request);
 165
 166         if(reqno || *request == '0') {
 167                 if(!is_valid_request(reqno) || !get_request_entry(reqno)->handler) {
 168                         logger(DEBUG_META, LOG_DEBUG, "Unknown request from %s (%s): %s", c->name, c->hostname, request);
 169                         return false;
 170                 }
 171
 172                 const request_entry_t *entry = get_request_entry(reqno);
 173                 logger(DEBUG_META, LOG_DEBUG, "Got %s from %s (%s): %s", entry->name, c->name, c->hostname, request);
 174
 175                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
 176                         logger(DEBUG_ALWAYS, LOG_ERR, "Unauthorized request from %s (%s)", c->name, c->hostname);
 177                         return false;
 178                 }
 179
 180                 if(!entry->handler(c, request)) {
 181                         /* Something went wrong. Probably scriptkiddies. Terminate. */
 182
 183                         if(reqno != TERMREQ) {
 184                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while processing %s from %s (%s)", entry->name, c->name, c->hostname);
 185                         }
 186
 187                         return false;
 188                 }
 189         } else {
 190                 logger(DEBUG_ALWAYS, LOG_ERR, "Bogus data received from %s (%s)", c->name, c->hostname);
 191                 return false;
 192         }
 193
 194         return true;
 195 }
 196
 197 static timeout_t past_request_timeout;
 198
 199 static void age_past_requests(void *data) {
 200         (void)data;
 201         int left = 0, deleted = 0;
 202
 203         for splay_each(past_request_t, p, &past_request_tree) {
 204                 if(p->firstseen + pinginterval <= now.tv_sec) {
 205                         splay_delete_node(&past_request_tree, node), deleted++;
 206                 } else {
 207                         left++;
 208                 }
 209         }
 210
 211         if(left || deleted) {
 212                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Aging past requests: deleted %d, left %d", deleted, left);
 213         }
 214
 215         if(left)
 216                 timeout_set(&past_request_timeout, &(struct timeval) {
 217                 10, jitter()
 218         });
 219 }
 220
 221 bool seen_request(const char *request) {
 222         past_request_t *new, p = {0};
 223
 224         p.request = request;
 225
 226         if(splay_search(&past_request_tree, &p)) {
 227                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Already seen request");
 228                 return true;
 229         } else {
 230                 new = xmalloc(sizeof(*new));
 231                 new->request = xstrdup(request);
 232                 new->firstseen = now.tv_sec;
 233                 splay_insert(&past_request_tree, new);
 234                 timeout_add(&past_request_timeout, age_past_requests, NULL, &(struct timeval) {
 235                         10, jitter()
 236                 });
 237                 return false;
 238         }
 239 }
 240
 241 void exit_requests(void) {
 242         splay_empty_tree(&past_request_tree);
 243
 244         timeout_del(&past_request_timeout);
 245 }