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- /*
- protocol.c -- handle the meta-protocol, basic functions
- Copyright (C) 1999-2005 Ivo Timmermans,
- 2000-2016 Guus Sliepen <guus@tinc-vpn.org>
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
- #include "system.h"
- #include "conf.h"
- #include "connection.h"
- #include "logger.h"
- #include "meta.h"
- #include "protocol.h"
- #include "utils.h"
- #include "xalloc.h"
- bool tunnelserver = false;
- bool strictsubnets = false;
- /* Jumptable for the request handlers */
- static bool (*request_handlers[])(connection_t *) = {
- id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
- NULL, NULL, NULL,
- ping_h, pong_h,
- add_subnet_h, del_subnet_h,
- add_edge_h, del_edge_h,
- key_changed_h, req_key_h, ans_key_h, tcppacket_h,
- };
- /* Request names */
- static char (*request_name[]) = {
- "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
- "STATUS", "ERROR", "TERMREQ",
- "PING", "PONG",
- "ADD_SUBNET", "DEL_SUBNET",
- "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET",
- };
- static avl_tree_t *past_request_tree;
- bool check_id(const char *id) {
- for(; *id; id++)
- if(!isalnum(*id) && *id != '_') {
- return false;
- }
- return true;
- }
- /* Generic request routines - takes care of logging and error
- detection as well */
- bool send_request(connection_t *c, const char *format, ...) {
- va_list args;
- char buffer[MAXBUFSIZE];
- int len, request = 0;
- /* Use vsnprintf instead of vxasprintf: faster, no memory
- fragmentation, cleanup is automatic, and there is a limit on the
- input buffer anyway */
- va_start(args, format);
- len = vsnprintf(buffer, sizeof(buffer), format, args);
- buffer[sizeof(buffer) - 1] = 0;
- va_end(args);
- if(len < 0 || (size_t)len > sizeof(buffer) - 1) {
- logger(LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
- c->name, c->hostname);
- return false;
- }
- ifdebug(PROTOCOL) {
- sscanf(buffer, "%d", &request);
- ifdebug(META)
- logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
- request_name[request], c->name, c->hostname, buffer);
- else
- logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[request],
- c->name, c->hostname);
- }
- buffer[len++] = '\n';
- if(c == everyone) {
- broadcast_meta(NULL, buffer, len);
- return true;
- } else {
- return send_meta(c, buffer, len);
- }
- }
- void forward_request(connection_t *from) {
- int request;
- ifdebug(PROTOCOL) {
- sscanf(from->buffer, "%d", &request);
- ifdebug(META)
- logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
- request_name[request], from->name, from->hostname,
- from->buffer);
- else
- logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
- request_name[request], from->name, from->hostname);
- }
- from->buffer[from->reqlen - 1] = '\n';
- broadcast_meta(from, from->buffer, from->reqlen);
- }
- bool receive_request(connection_t *c) {
- int request;
- if(sscanf(c->buffer, "%d", &request) == 1) {
- if((request < 0) || (request >= LAST) || !request_handlers[request]) {
- ifdebug(META)
- logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
- c->name, c->hostname, c->buffer);
- else
- logger(LOG_ERR, "Unknown request from %s (%s)",
- c->name, c->hostname);
- return false;
- } else {
- ifdebug(PROTOCOL) {
- ifdebug(META)
- logger(LOG_DEBUG, "Got %s from %s (%s): %s",
- request_name[request], c->name, c->hostname,
- c->buffer);
- else
- logger(LOG_DEBUG, "Got %s from %s (%s)",
- request_name[request], c->name, c->hostname);
- }
- }
- if((c->allow_request != ALL) && (c->allow_request != request)) {
- logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
- c->hostname);
- return false;
- }
- if(!request_handlers[request](c)) {
- /* Something went wrong. Probably scriptkiddies. Terminate. */
- logger(LOG_ERR, "Error while processing %s from %s (%s)",
- request_name[request], c->name, c->hostname);
- return false;
- }
- } else {
- logger(LOG_ERR, "Bogus data received from %s (%s)",
- c->name, c->hostname);
- return false;
- }
- return true;
- }
- static int past_request_compare(const past_request_t *a, const past_request_t *b) {
- return strcmp(a->request, b->request);
- }
- static void free_past_request(past_request_t *r) {
- if(r->request) {
- free(r->request);
- }
- free(r);
- }
- void init_requests(void) {
- past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
- }
- void exit_requests(void) {
- avl_delete_tree(past_request_tree);
- }
- bool seen_request(char *request) {
- past_request_t *new, p = {};
- p.request = request;
- if(avl_search(past_request_tree, &p)) {
- ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
- return true;
- } else {
- new = xmalloc(sizeof(*new));
- new->request = xstrdup(request);
- new->firstseen = now;
- avl_insert(past_request_tree, new);
- return false;
- }
- }
- void age_past_requests(void) {
- avl_node_t *node, *next;
- past_request_t *p;
- int left = 0, deleted = 0;
- for(node = past_request_tree->head; node; node = next) {
- next = node->next;
- p = node->data;
- if(p->firstseen + pinginterval <= now) {
- avl_delete_node(past_request_tree, node), deleted++;
- } else {
- left++;
- }
- }
- if(left || deleted)
- ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
- deleted, left);
- }
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