toxcore/toxdns/toxdns.h

/* toxdns.h
 *
 * Tox secure username DNS toxid resolving functions.
 *
 *  Copyright (C) 2014 Tox project All Rights Reserved.
 *
 *  This file is part of Tox.
 *
 *  Tox 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  Tox 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 Tox.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef TOXDNS_H
#define TOXDNS_H

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>

/* Clients are encouraged to set this as the maximum length names can have. */
#define TOXDNS_MAX_RECOMMENDED_NAME_LENGTH 32

/* How to use this api to make secure tox dns3 requests:
 *
 * 1. Get the public key of a server that supports tox dns3.
 * 2. use tox_dns3_new() to create a new object to create DNS requests
 * and handle responses for that server.
 * 3. Use tox_generate_dns3_string() to generate a string based on the name we want to query and a request_id
 * that must be stored somewhere for when we want to decrypt the response.
 * 4. take the string and use it for your DNS request like this:
 * _4haaaaipr1o3mz0bxweox541airydbovqlbju51mb4p0ebxq.rlqdj4kkisbep2ks3fj2nvtmk4daduqiueabmexqva1jc._tox.utox.org
 * 5. The TXT in the DNS you receive should look like this:
 * v=tox3;id=2vgcxuycbuctvauik3plsv3d3aadv4zfjfhi3thaizwxinelrvigchv0ah3qjcsx5qhmaksb2lv2hm5cwbtx0yp
 * 6. Take the id string and use it with tox_decrypt_dns3_TXT() and the request_id corresponding to the
 * request we stored earlier to get the Tox id returned by the DNS server.
 */

/* Create a new tox_dns3 object for server with server_public_key of size TOX_CLIENT_ID_SIZE.
 *
 * return Null on failure.
 * return pointer object on success.
 */
void *tox_dns3_new(uint8_t *server_public_key);

/* Destroy the tox dns3 object.
 */
void tox_dns3_kill(void *dns3_object);

/* Generate a dns3 string of string_max_len used to query the dns server referred to by to
 * dns3_object for a tox id registered to user with name of name_len.
 *
 * the uint32_t pointed by request_id will be set to the request id which must be passed to
 * tox_decrypt_dns3_TXT() to correctly decode the response.
 *
 * This is what the string returned looks like:
 * 4haaaaipr1o3mz0bxweox541airydbovqlbju51mb4p0ebxq.rlqdj4kkisbep2ks3fj2nvtmk4daduqiueabmexqva1jc
 *
 * returns length of string on success.
 * returns -1 on failure.
 */
int tox_generate_dns3_string(void *dns3_object, uint8_t *string, uint16_t string_max_len, uint32_t *request_id,
                             uint8_t *name, uint8_t name_len);

/* Decode and decrypt the id_record returned of length id_record_len into
 * tox_id (needs to be at least TOX_FRIEND_ADDRESS_SIZE).
 *
 * request_id is the request id given by tox_generate_dns3_string() when creating the request.
 *
 * the id_record passed to this function should look somewhat like this:
 * 2vgcxuycbuctvauik3plsv3d3aadv4zfjfhi3thaizwxinelrvigchv0ah3qjcsx5qhmaksb2lv2hm5cwbtx0yp
 *
 * returns -1 on failure.
 * returns 0 on success.
 *
 */
int tox_decrypt_dns3_TXT(void *dns3_object, uint8_t *tox_id, uint8_t *id_record, uint32_t id_record_len,
                         uint32_t request_id);

#ifdef __cplusplus
}
#endif

#endif