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