37a924be6a
The current DNS caching logic is not aware of the IP address version. If there is a cached address for a query, the caller of dns_get_addr_info() will receive that address, even if it is not the same version as the caller requested. For example: - dns_get_addr_info() is called to resolve an IPv4 address - the DNS client caches the IPv4 address that was received - dns_get_addr_info() is called to resolve an IPv6 address - the DNS client sees that there is a cached IPv4 address for the given query - the DNS client does not check that the cached address is of the requested version (IPv6) - the cached IPv4 address is returned from dns_get_addr_info() This changes the DNS client to check IP address version when searching cached addresses. Signed-off-by: Noah Olson <noah@wavelynx.com>
102 lines
3.4 KiB
C
102 lines
3.4 KiB
C
/** @file
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* @brief DNS cache
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*
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* An cache holding dns records for faster dns resolving.
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*/
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/*
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* Copyright (c) 2024 Endress+Hauser AG
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_NET_DNS_CACHE_H_
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#define ZEPHYR_INCLUDE_NET_DNS_CACHE_H_
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#include <stdint.h>
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#include <zephyr/net/dns_resolve.h>
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#include <zephyr/kernel.h>
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#include <zephyr/sys_clock.h>
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struct dns_cache_entry {
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char query[CONFIG_DNS_RESOLVER_MAX_QUERY_LEN];
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struct dns_addrinfo data;
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k_timepoint_t expiry;
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bool in_use;
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};
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struct dns_cache {
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size_t size;
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struct dns_cache_entry *entries;
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struct k_mutex *lock;
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};
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/**
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* @brief Statically define and initialize a DNS queue.
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*
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* The cache can be accessed outside the module where it is defined using:
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*
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* @code extern struct dns_cache <name>; @endcode
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*
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* @param name Name of the cache.
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*/
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#define DNS_CACHE_DEFINE(name, cache_size) \
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static K_MUTEX_DEFINE(name##_mutex); \
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static struct dns_cache_entry name##_entries[cache_size]; \
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static struct dns_cache name = { \
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.entries = name##_entries, .size = cache_size, .lock = &name##_mutex};
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/**
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* @brief Flushes the dns cache removing all its entries.
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*
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* @param cache Cache to be flushed
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* @retval 0 on success
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* @retval On error, a negative value is returned.
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*/
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int dns_cache_flush(struct dns_cache *cache);
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/**
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* @brief Adds a new entry to the dns cache removing the one closest to expiry
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* if no free space is available.
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*
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* @param cache Cache where the entry should be added.
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* @param query Query which should be persisted in the cache.
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* @param addrinfo Addrinfo resulting from the query which will be returned
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* upon cache hit.
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* @param ttl Time to live for the entry in seconds. This usually represents
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* the TTL of the RR.
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* @retval 0 on success
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* @retval On error, a negative value is returned.
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*/
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int dns_cache_add(struct dns_cache *cache, char const *query, struct dns_addrinfo const *addrinfo,
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uint32_t ttl);
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/**
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* @brief Removes all entries with the given query
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*
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* @param cache Cache where the entries should be removed.
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* @param query Query which should be searched for.
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* @retval 0 on success
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* @retval On error, a negative value is returned.
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*/
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int dns_cache_remove(struct dns_cache *cache, char const *query);
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/**
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* @brief Tries to find the specified query entry within the cache.
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*
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* @param cache Cache where the entry should be searched.
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* @param query Query which should be searched for.
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* @param type Query type which will control the types of addresses that will be found.
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* @param addrinfo dns_addrinfo array which will be written if the query was found.
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* @param addrinfo_array_len Array size of the dns_addrinfo array
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* @retval on success the amount of dns_addrinfo written into the addrinfo array will be returned.
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* A cache miss will therefore return a 0.
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* @retval On error a negative value is returned.
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* -ENOSR means there was not enough space in the addrinfo array to accommodate all cache hits the
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* array will however be filled with valid data.
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*/
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int dns_cache_find(struct dns_cache const *cache, const char *query, enum dns_query_type type,
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struct dns_addrinfo *addrinfo, size_t addrinfo_array_len);
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#endif /* ZEPHYR_INCLUDE_NET_DNS_CACHE_H_ */
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