1 /* 2 * Copyright (c) 2020 Friedt Professional Engineering Services, Inc 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #ifndef DNS_SD_H_ 8 #define DNS_SD_H_ 9 10 #include <stdbool.h> 11 #include <stdint.h> 12 #include <string.h> 13 14 #include <zephyr/net/dns_sd.h> 15 #include <zephyr/net/net_ip.h> 16 #include <zephyr/sys/iterable_sections.h> 17 18 #include "dns_pack.h" 19 20 /* TODO: Move these into Kconfig */ 21 #define DNS_SD_PTR_TTL 4500 22 #define DNS_SD_TXT_TTL 4500 23 #define DNS_SD_SRV_TTL 120 24 #define DNS_SD_A_TTL 120 25 #define DNS_SD_AAAA_TTL 120 26 27 #define DNS_SD_PTR_MASK (NS_CMPRSFLGS << 8) 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 #define DNS_SD_FOREACH(it) \ 34 STRUCT_SECTION_FOREACH(dns_sd_rec, it) 35 36 /** 37 * @brief Extract labels from a DNS-SD PTR query 38 * 39 * ``` 40 * <sn>._tcp.<domain>. 41 * <instance>.<sn>._tcp.<domain>. 42 * ``` 43 * 44 * Currently sub-types and service domains are unsupported and only the 45 * "local" domain is supported. Specifically, that excludes the following: 46 * ``` 47 * <sub>._sub.<sn>._tcp.<servicedomain>.<parentdomain>. 48 * ``` 49 * 50 * @param query a pointer to the start of the query 51 * @param query_size the number of bytes contained in the query 52 * @param[out] record the DNS-SD record to initialize and populate 53 * @param label array of pointers to suitably sized buffers 54 * @param size array of sizes for each buffer in @p label 55 * @param[inout] n number of elements in @p label and @p size 56 * 57 * @return on success, number of bytes read from @p query 58 * @return on failure, a negative errno value 59 * 60 * @see <a href="https://datatracker.ietf.org/doc/html/rfc6763">RFC 6763</a>, Section 7.2. 61 */ 62 int dns_sd_query_extract(const uint8_t *query, size_t query_size, struct dns_sd_rec *record, 63 char **label, size_t *size, size_t *n); 64 65 /** 66 * @brief Extract the Service, Protocol, and Domain from a DNS-SD PTR query 67 * 68 * This function zero-initializes @p record and populates the appropriate 69 * fields so that @p record may be subsequently passed to @ref dns_sd_rec_match. 70 * 71 * If a query with a supported format is found, the function returns the 72 * length of the initial, variable-length portion of the query. 73 * 74 * For example, if the query begins with "._foo._tcp.local.", where 75 * the '.' character represents a length of the subsequent string value, 76 * then this function will return 17. 77 * 78 * @param query a pointer to the start of the query 79 * @param query_size the number of bytes contained in the query 80 * @param[out] record the DNS-SD record to initialize and populate 81 * @param service buffer to store the null-terminated service 82 * @param service_size the size of @p service 83 * @param proto buffer to store the null-terminated proto 84 * @param proto_size the size of @p proto 85 * @param domain buffer to store the null-terminated domain 86 * @param domain_size the size of @p domain 87 * @return on success, a positive number representing length of the query 88 * @return on failure, a negative errno value 89 */ 90 __deprecated 91 int dns_sd_extract_service_proto_domain(const uint8_t *query, 92 size_t query_size, struct dns_sd_rec *record, char *service, 93 size_t service_size, char *proto, size_t proto_size, 94 char *domain, size_t domain_size); 95 96 /** 97 * @brief See if the DNS SD @p filter matches the @p record 98 * 99 * The fields in @p filter should be populated with filter elements to 100 * identify a possible match. If pointer fields are set to NULL, they 101 * act as a wildcard in the matching process. I.e. they will match 102 * anything. Similarly, the @ref dns_sd_rec.port field may be set to 0 103 * to be used as a wildcard. 104 * 105 * The @ref dns_sd_rec.text and @ref dns_ds_rec.text_size fields 106 * are not included in the matching process. 107 * 108 * For example, the filter below can be used to match any 109 * "_http._tcp" records. 110 * 111 * @code{c} 112 * const struct dns_sd_rec *it; 113 * struct dns_sd_rec filter = { 114 * // match any instance 115 * .instance = NULL, 116 * // match records with service "_http" 117 * .service = "_http", 118 * // match records with protocol "_tcp" 119 * .proto = "_tcp", 120 * // match any domain 121 * .domain = NULL, 122 * // match any port 123 * .port = 0, 124 * }; 125 * 126 * DNS_SD_FOREACH(it) { 127 * if (dns_sd_rec_match(it, filter)) { 128 * // found a match! 129 * } 130 * } 131 * @endcode{c} 132 * 133 * @param record The reference DNS-SD record 134 * @param filter The DNS-SD record filter 135 * 136 * @return true if the @p record matches the @p filter 137 * @return false if @p record is not a match for @p filter 138 * @return false if either @p record or @p filter are invalid 139 */ 140 bool dns_sd_rec_match(const struct dns_sd_rec *record, 141 const struct dns_sd_rec *filter); 142 143 /** 144 * @brief Handle a DNS PTR Query with DNS Service Discovery 145 * 146 * This function should be called once for each DNS-SD record that 147 * matches a particular DNS PTR query. 148 * 149 * If there is no IPv4 address to advertise, then @p addr4 should be 150 * NULL. 151 * 152 * If there is no IPv6 address to advertise, then @p addr6 should be 153 * NULL. 154 * 155 * @param inst the DNS-SD record to advertise 156 * @param addr4 pointer to the IPv4 address 157 * @param addr6 pointer to the IPv6 address 158 * @param buf output buffer 159 * @param buf_size size of the output buffer 160 * 161 * @return on success, number of bytes written to @p buf 162 * @return on failure, a negative errno value 163 */ 164 int dns_sd_handle_ptr_query(const struct dns_sd_rec *inst, 165 const struct in_addr *addr4, const struct in6_addr *addr6, 166 uint8_t *buf, uint16_t buf_size); 167 168 /** 169 * @brief Handle a Service Type Enumeration with DNS Service Discovery 170 * 171 * This function should be called once for each type of advertised service. 172 * 173 * @param service the DNS-SD service to advertise 174 * @param addr4 pointer to the IPv4 address 175 * @param addr6 pointer to the IPv6 address 176 * @param buf output buffer 177 * @param buf_size size of the output buffer 178 * 179 * @return on success, number of bytes written to @p buf 180 * @return on failure, a negative errno value 181 */ 182 int dns_sd_handle_service_type_enum(const struct dns_sd_rec *service, 183 const struct in_addr *addr4, const struct in6_addr *addr6, 184 uint8_t *buf, uint16_t buf_size); 185 186 #ifdef __cplusplus 187 }; 188 #endif 189 190 #endif /* DNS_SD_H_ */ 191
