1 /*
2 * Copyright (c) 2024 Endress+Hauser AG
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/net/dns_resolve.h>
8 #include <zephyr/net/net_ip.h>
9 #include "dns_cache.h"
10
11 LOG_MODULE_REGISTER(net_dns_cache, CONFIG_DNS_RESOLVER_LOG_LEVEL);
12
13 static void dns_cache_clean(struct dns_cache const *cache);
14
dns_cache_flush(struct dns_cache * cache)15 int dns_cache_flush(struct dns_cache *cache)
16 {
17 k_mutex_lock(cache->lock, K_FOREVER);
18 for (size_t i = 0; i < cache->size; i++) {
19 cache->entries[i].in_use = false;
20 }
21 k_mutex_unlock(cache->lock);
22
23 return 0;
24 }
25
dns_cache_add(struct dns_cache * cache,char const * query,struct dns_addrinfo const * addrinfo,uint32_t ttl)26 int dns_cache_add(struct dns_cache *cache, char const *query, struct dns_addrinfo const *addrinfo,
27 uint32_t ttl)
28 {
29 k_timepoint_t closest_to_expiry = sys_timepoint_calc(K_FOREVER);
30 size_t index_to_replace = 0;
31 bool found_empty = false;
32
33 if (cache == NULL || query == NULL || addrinfo == NULL || ttl == 0) {
34 return -EINVAL;
35 }
36
37 if (strlen(query) >= CONFIG_DNS_RESOLVER_MAX_QUERY_LEN) {
38 NET_WARN("Query string to big to be processed %u >= "
39 "CONFIG_DNS_RESOLVER_MAX_QUERY_LEN",
40 strlen(query));
41 return -EINVAL;
42 }
43
44 k_mutex_lock(cache->lock, K_FOREVER);
45
46 NET_DBG("Add \"%s\" with TTL %" PRIu32, query, ttl);
47
48 dns_cache_clean(cache);
49
50 for (size_t i = 0; i < cache->size; i++) {
51 if (!cache->entries[i].in_use) {
52 index_to_replace = i;
53 found_empty = true;
54 break;
55 } else if (sys_timepoint_cmp(closest_to_expiry, cache->entries[i].expiry) > 0) {
56 index_to_replace = i;
57 closest_to_expiry = cache->entries[i].expiry;
58 }
59 }
60
61 if (!found_empty) {
62 NET_DBG("Overwrite \"%s\"", cache->entries[index_to_replace].query);
63 }
64
65 strncpy(cache->entries[index_to_replace].query, query,
66 CONFIG_DNS_RESOLVER_MAX_QUERY_LEN - 1);
67 cache->entries[index_to_replace].data = *addrinfo;
68 cache->entries[index_to_replace].expiry = sys_timepoint_calc(K_SECONDS(ttl));
69 cache->entries[index_to_replace].in_use = true;
70
71 k_mutex_unlock(cache->lock);
72
73 return 0;
74 }
75
dns_cache_remove(struct dns_cache * cache,char const * query)76 int dns_cache_remove(struct dns_cache *cache, char const *query)
77 {
78 NET_DBG("Remove all entries with query \"%s\"", query);
79 if (strlen(query) >= CONFIG_DNS_RESOLVER_MAX_QUERY_LEN) {
80 NET_WARN("Query string to big to be processed %u >= "
81 "CONFIG_DNS_RESOLVER_MAX_QUERY_LEN",
82 strlen(query));
83 return -EINVAL;
84 }
85
86 k_mutex_lock(cache->lock, K_FOREVER);
87
88 dns_cache_clean(cache);
89
90 for (size_t i = 0; i < cache->size; i++) {
91 if (cache->entries[i].in_use && strcmp(cache->entries[i].query, query) == 0) {
92 cache->entries[i].in_use = false;
93 }
94 }
95
96 k_mutex_unlock(cache->lock);
97
98 return 0;
99 }
100
dns_cache_find(struct dns_cache const * cache,const char * query,enum dns_query_type type,struct dns_addrinfo * addrinfo,size_t addrinfo_array_len)101 int dns_cache_find(struct dns_cache const *cache, const char *query, enum dns_query_type type,
102 struct dns_addrinfo *addrinfo, size_t addrinfo_array_len)
103 {
104 size_t found = 0;
105 sa_family_t family;
106
107 NET_DBG("Find \"%s\"", query);
108 if (cache == NULL || query == NULL || addrinfo == NULL || addrinfo_array_len <= 0) {
109 return -EINVAL;
110 }
111 if (type == DNS_QUERY_TYPE_A) {
112 family = AF_INET;
113 } else if (type == DNS_QUERY_TYPE_AAAA) {
114 family = AF_INET6;
115 } else {
116 return -EINVAL;
117 }
118 if (strlen(query) >= CONFIG_DNS_RESOLVER_MAX_QUERY_LEN) {
119 NET_WARN("Query string to big to be processed %u >= "
120 "CONFIG_DNS_RESOLVER_MAX_QUERY_LEN",
121 strlen(query));
122 return -EINVAL;
123 }
124
125 k_mutex_lock(cache->lock, K_FOREVER);
126
127 dns_cache_clean(cache);
128
129 for (size_t i = 0; i < cache->size; i++) {
130 if (!cache->entries[i].in_use) {
131 continue;
132 }
133 if (strcmp(cache->entries[i].query, query) != 0) {
134 continue;
135 }
136 if (cache->entries[i].data.ai_family != family) {
137 continue;
138 }
139 if (found >= addrinfo_array_len) {
140 NET_WARN("Found \"%s\" but not enough space in provided buffer.", query);
141 found++;
142 } else {
143 addrinfo[found] = cache->entries[i].data;
144 found++;
145 NET_DBG("Found \"%s\"", query);
146 }
147 }
148
149 k_mutex_unlock(cache->lock);
150
151 if (found > addrinfo_array_len) {
152 return -ENOSR;
153 }
154
155 if (found == 0) {
156 NET_DBG("Could not find \"%s\"", query);
157 }
158 return found;
159 }
160
161 /* Needs to be called when lock is already acquired */
dns_cache_clean(struct dns_cache const * cache)162 static void dns_cache_clean(struct dns_cache const *cache)
163 {
164 for (size_t i = 0; i < cache->size; i++) {
165 if (!cache->entries[i].in_use) {
166 continue;
167 }
168
169 if (sys_timepoint_expired(cache->entries[i].expiry)) {
170 NET_DBG("Remove \"%s\"", cache->entries[i].query);
171 cache->entries[i].in_use = false;
172 }
173 }
174 }
175
