net: dns: Add service discovery support (cf8b7d71) · Commits · Wenxi XU / zephyr

include/zephyr/net/dns_resolve.h

+42 −2

Changes for include/zephyr/net/dns_resolve.h: 42 added lines, 2 removed lines.
Original line number	Diff line number	Diff line
		@@ -45,9 +45,11 @@ enum dns_query_type {
		};

		/** Max size of the resolved name. */
		#ifndef DNS_MAX_NAME_SIZE
		#if defined(CONFIG_DNS_RESOLVER_MAX_NAME_LEN)
		#define DNS_MAX_NAME_SIZE CONFIG_DNS_RESOLVER_MAX_NAME_LEN
		#else
		#define DNS_MAX_NAME_SIZE 20
		#endif
		#endif /* CONFIG_DNS_RESOLVER_MAX_NAME_LEN */

		/** @cond INTERNAL_HIDDEN */

		@@ -628,6 +630,44 @@ int dns_resolve_name(struct dns_resolve_context *ctx,
		void *user_data,
		int32_t timeout);

		/**
		* @brief Resolve DNS service.
		*
		* @details This function can be used to resolve service records needed in
		* DNS-SD service discovery.
		* Note that this is an asynchronous call, the function will return immediately
		* and the system will call the callback after resolving has finished or a timeout
		* has occurred.
		* We might send the query to multiple servers (if there are more than one
		* server configured), but we only use the result of the first received
		* response.
		*
		* @param ctx DNS context
		* @param query What the caller wants to resolve.
		* @param dns_id DNS id is returned to the caller. This is needed if one
		* wishes to cancel the query. This can be set to NULL if there is no need
		* to cancel the query.
		* @param cb Callback to call after the resolving has finished or timeout
		* has happened.
		* @param user_data The user data.
		* @param timeout The timeout value for the query. Possible values:
		* SYS_FOREVER_MS: the query is tried forever, user needs to cancel it
		* manually if it takes too long time to finish
		* >0: start the query and let the system timeout it after specified ms
		*
		* @return 0 if resolving was started ok, < 0 otherwise
		*/
		static inline int dns_resolve_service(struct dns_resolve_context *ctx,
		const char *query,
		uint16_t *dns_id,
		dns_resolve_cb_t cb,
		void *user_data,
		int32_t timeout)
		{
		return dns_resolve_name(ctx, query, DNS_QUERY_TYPE_PTR,
		dns_id, cb, user_data, timeout);
		}

		/**
		* @brief Get default DNS context.
		*

subsys/net/lib/dns/Kconfig

+10 −0

Changes for subsys/net/lib/dns/Kconfig: 10 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		@@ -69,6 +69,16 @@ config DNS_RESOLVER_MAX_QUERY_LEN
		Max length of a DNS query that should be looked up including the
		trailing 0. So e.g. "example.com" would have a query len of 12.

		config DNS_RESOLVER_MAX_NAME_LEN
		int "Max length of the resolved DNS name"
		range 1 $(UINT8_MAX)
		default 128 if DNS_SD
		default 20
		help
		Max length of a buffer that is used to store information returned from
		DNS server. For example if we query a DNS-SD service, then this value should
		be long enough to store the returned string.

		menuconfig DNS_SERVER_IP_ADDRESSES
		bool "Set DNS server IP addresses"
		help

subsys/net/lib/dns/dns_pack.c

+7 −2

Changes for subsys/net/lib/dns/dns_pack.c: 7 added lines, 2 removed lines.
Original line number	Diff line number	Diff line
		@@ -166,6 +166,10 @@ int dns_unpack_answer(struct dns_msg_t dns_msg, int dname_ptr, uint32_t ttl,
		set_dns_msg_response(dns_msg, DNS_RESPONSE_IP, pos, len);
		return 0;

		case DNS_RR_TYPE_PTR:
		set_dns_msg_response(dns_msg, DNS_RESPONSE_DATA, pos, len);
		return 0;

		case DNS_RR_TYPE_CNAME:
		set_dns_msg_response(dns_msg, DNS_RESPONSE_CNAME_NO_IP,
		pos, len);
		@@ -346,7 +350,8 @@ int dns_unpack_response_query(struct dns_msg_t *dns_msg)

		buf = dns_query + qname_size;
		if (dns_unpack_query_qtype(buf) != DNS_RR_TYPE_A &&
		dns_unpack_query_qtype(buf) != DNS_RR_TYPE_AAAA) {
		dns_unpack_query_qtype(buf) != DNS_RR_TYPE_AAAA &&
		dns_unpack_query_qtype(buf) != DNS_RR_TYPE_PTR) {
		return -EINVAL;
		}

		@@ -482,7 +487,7 @@ int mdns_unpack_query_header(struct dns_msg_t msg, uint16_t src_id)
		}

		/* Returns the length of the unpacked name */
		static int dns_unpack_name(const uint8_t msg, int maxlen, const uint8_t src,
		int dns_unpack_name(const uint8_t msg, int maxlen, const uint8_t src,
		struct net_buf buf, const uint8_t *eol)
		{
		int dest_size = net_buf_tailroom(buf);

subsys/net/lib/dns/dns_pack.h

+4 −0

Changes for subsys/net/lib/dns/dns_pack.h: 4 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		@@ -100,6 +100,7 @@ enum dns_rr_type {
		enum dns_response_type {
		DNS_RESPONSE_INVALID = -EINVAL,
		DNS_RESPONSE_IP,
		DNS_RESPONSE_DATA,
		DNS_RESPONSE_CNAME_WITH_IP,
		DNS_RESPONSE_CNAME_NO_IP
		};
		@@ -473,4 +474,7 @@ int dns_unpack_query(struct dns_msg_t dns_msg, struct net_buf buf,
		*/
		const char *dns_qtype_to_str(enum dns_rr_type qtype);

		int dns_unpack_name(const uint8_t msg, int maxlen, const uint8_t src,
		struct net_buf buf, const uint8_t *eol);

		#endif

subsys/net/lib/dns/resolve.c

+46 −0

Changes for subsys/net/lib/dns/resolve.c: 46 added lines, 0 removed lines.
Original line number	Diff line number	Diff line
		@@ -1097,6 +1097,7 @@ int dns_validate_msg(struct dns_resolve_context *ctx,
		}

		switch (dns_msg->response_type) {
		case DNS_RESPONSE_DATA:
		case DNS_RESPONSE_IP: {
		int query_name_len;

		@@ -1205,11 +1206,55 @@ rr_qtype_aaaa:
		ret = DNS_EAI_ADDRFAMILY;
		goto quit;
		}

		} else if (ctx->queries[*query_idx].query_type ==
		DNS_QUERY_TYPE_PTR) {
		/* Synthesize a reply and place the returned info
		* in to the ai_canonname field. Use AF_LOCAL address
		* family as this is not a real address.
		*/
		struct net_buf *result;
		uint8_t *pos;

		address_size = MIN(dns_msg->response_length,
		DNS_MAX_NAME_SIZE);

		/* Temporary buffer that is needed by dns_unpack_name()
		* to unpack the resolved name.
		*/
		result = net_buf_alloc(&dns_qname_pool, ctx->buf_timeout);
		if (result == NULL) {
		NET_DBG("Cannot allocate buffer for DNS query result");
		ret = DNS_EAI_MEMORY;
		goto quit;
		}

		pos = dns_msg->msg + dns_msg->response_position;
		ret = dns_unpack_name(dns_msg->msg, dns_msg->msg_size, pos,
		result, NULL);
		if (ret < 0) {
		errno = -ret;
		ret = DNS_EAI_SYSTEM;
		net_buf_unref(result);
		goto quit;
		}

		info.ai_family = AF_LOCAL;
		info.ai_addrlen = MIN(result->len, DNS_MAX_NAME_SIZE);
		memcpy(&info.ai_canonname, result->data, info.ai_addrlen);
		info.ai_canonname[info.ai_addrlen] = '\0';

		net_buf_unref(result);

		} else {
		ret = DNS_EAI_FAMILY;
		goto quit;
		}

		if (ctx->queries[*query_idx].query_type ==
		DNS_QUERY_TYPE_A \|\|
		ctx->queries[*query_idx].query_type ==
		DNS_QUERY_TYPE_AAAA) {
		if (dns_msg->response_length < address_size) {
		/* it seems this is a malformed message */
		errno = EMSGSIZE;
		@@ -1227,6 +1272,7 @@ rr_qtype_aaaa:

		src = dns_msg->msg + dns_msg->response_position;
		memcpy(addr, src, address_size);
		}

		invoke_query_callback(DNS_EAI_INPROGRESS, &info,
		&ctx->queries[*query_idx]);

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