1
0
mirror of https://github.com/RIOT-OS/RIOT.git synced 2024-12-29 04:50:03 +01:00
RIOT/sys/include/net/dns/msg.h
2022-07-13 23:23:52 +02:00

122 lines
3.7 KiB
C

/*
* Copyright (C) 2021 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup net_dns_msg DNS message parser and composer
* @ingroup net_dns
* @brief Parsing and composition of DNS messages
* @{
*
* @file
* @brief Definitions for parsing and composition of DNS messages
*
* @author Martine Lenders <m.lenders@fu-berlin.de>
*/
#ifndef NET_DNS_MSG_H
#define NET_DNS_MSG_H
#include <stdint.h>
#include <stdlib.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup net_dns_msg_conf DNS message parsing and composition configuration
* @ingroup config
* @{
*/
/**
* @brief maximum DNS message length
*/
#ifndef CONFIG_DNS_MSG_LEN
#define CONFIG_DNS_MSG_LEN (128U)
#endif /* CONFIG_DNS_MSG_LEN */
/** @} */
/**
* @brief DNS internal structure
*
* @see [RFC 1035, section 4.1.1](https://tools.ietf.org/html/rfc1035#section-4.1.1)
*/
typedef struct __attribute__((packed)) {
uint16_t id; /**< identifier */
/**
* @brief flags
*
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* |QR| Opcode |AA|TC|RD|RA|Z |AD|CD| RCODE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*
* - QR: Query (0) or Response (1)
* - Opcode: Kind of query
* - AA: Authoritative Answer
* - TC: Truncated
* - RD: Recursion Desired
* - RA: Recursion Available
* - Z: Reserved
* - AD: Authentic Data (see [RFC 4035](https://tools.ietf.org/html/4035))
* - CD: Checking Disabled (see [RFC 4035](https://tools.ietf.org/html/4035))
* - RCODE: Response Code
*/
uint16_t flags;
uint16_t qdcount; /**< number of question entries */
uint16_t ancount; /**< number of answer resource records */
uint16_t nscount; /**< number of name server resource records */
uint16_t arcount; /**< number of additional records */
uint8_t payload[]; /**< payload */
} dns_hdr_t;
/**
* @brief Composes a DNS query message
*
* The query will request an A or AAAA IN record for @p domain_name depending on
* @p family:
*
* - When @p family is `AF_INET` or `AF_UNSPEC` a query for an A record will be
* added
* - When @p family is `AF_INET6` or `AF_UNSPEC` a query for an AAAA record will
* be added
*
* @param[out] dns_buf A buffer of length @ref CONFIG_DNS_MSG_LEN
* @param[in] domain_name The domain name to query.
* @param[in] id The ID for the query.
* @param[in] family Either `AF_UNSPEC`, `AF_INET`, or `AF_INET6`.
* Determines the address records for @p domain_name
* queried.
*
* @return Size of the composed query in bytes.
*/
size_t dns_msg_compose_query(void *dns_buf, const char *domain_name,
uint16_t id, int family);
/**
* @brief Parses a DNS response message
*
* @param[in] buf The message to parse.
* @param[in] len Length of @p buf.
* @param[in] family The address family used to compose the query for
* this response (see @ref dns_msg_compose_query())
* @param[out] addr_out The IP address returned by the response.
* @param[out] ttl The live time of the entry in seconds
*
* @return Length of the @p addr_out on success.
* @return -EBADMSG, when an address corresponding to @p family can not be found
* in @p buf.
*/
int dns_msg_parse_reply(const uint8_t *buf, size_t len, int family,
void *addr_out, uint32_t *ttl);
#ifdef __cplusplus
}
#endif
#endif /* NET_DNS_MSG_H */
/** @} */