net: dns: Support multiple simultaneous mDNS requests
As mDNS requests set DNS id to 0, we cannot use it to match the DNS response packet. In order to allow this functionality, create a hash from query name and type, and use that together with DNS id to match request and response. Fixes #21914 Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
This commit is contained in:
Jukka Rissanen
parent
e25394bca9
commit
f9c18dd962
2 changed files with 209 additions and 68 deletions
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@ -208,6 +208,14 @@ struct dns_resolve_context {
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/** DNS id of this query */
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u16_t id;
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/** Hash of the DNS name + query type we are querying.
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* This hash is calculated so we can match the response that
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* we are receiving. This is needed mainly for mDNS which is
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* setting the DNS id to 0, which means that the id alone
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* cannot be used to find correct pending query.
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*/
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u16_t query_hash;
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} queries[CONFIG_DNS_NUM_CONCUR_QUERIES];
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/** Is this context in use */
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@ -270,6 +278,23 @@ int dns_resolve_close(struct dns_resolve_context *ctx);
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int dns_resolve_cancel(struct dns_resolve_context *ctx,
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u16_t dns_id);
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/**
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* @brief Cancel a pending DNS query using id, name and type.
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*
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* @details This releases DNS resources used by a pending query.
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*
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* @param ctx DNS context
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* @param dns_id DNS id of the pending query
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* @param query_name Name of the resource we are trying to query (hostname)
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* @param query_type Type of the query (A or AAAA)
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*
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* @return 0 if ok, <0 if error.
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*/
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int dns_resolve_cancel_with_name(struct dns_resolve_context *ctx,
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u16_t dns_id,
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const char *query_name,
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enum dns_query_type query_type);
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/**
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* @brief Resolve DNS name.
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*
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@ -18,6 +18,7 @@ LOG_MODULE_REGISTER(net_dns_resolve, CONFIG_DNS_RESOLVER_LOG_LEVEL);
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#include <errno.h>
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#include <stdlib.h>
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#include <sys/crc.h>
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#include <net/net_ip.h>
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#include <net/net_pkt.h>
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#include <net/net_mgmt.h>
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@ -342,12 +343,15 @@ static inline int get_cb_slot(struct dns_resolve_context *ctx)
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}
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static inline int get_slot_by_id(struct dns_resolve_context *ctx,
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u16_t dns_id)
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u16_t dns_id,
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u16_t query_hash)
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{
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int i;
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for (i = 0; i < CONFIG_DNS_NUM_CONCUR_QUERIES; i++) {
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if (ctx->queries[i].cb && ctx->queries[i].id == dns_id) {
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if (ctx->queries[i].cb && ctx->queries[i].id == dns_id &&
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(query_hash == 0 ||
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ctx->queries[i].query_hash == query_hash)) {
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return i;
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}
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}
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@ -359,20 +363,22 @@ static int dns_read(struct dns_resolve_context *ctx,
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struct net_pkt *pkt,
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struct net_buf *dns_data,
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u16_t *dns_id,
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struct net_buf *dns_cname)
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struct net_buf *dns_cname,
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u16_t *query_hash)
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{
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struct dns_addrinfo info = { 0 };
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/* Helper struct to track the dns msg received from the server */
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struct dns_msg_t dns_msg;
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u32_t ttl; /* RR ttl, so far it is not passed to caller */
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u8_t *src, *addr;
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const char *query_name;
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int address_size;
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/* index that points to the current answer being analyzed */
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int answer_ptr;
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int data_len;
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int items;
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int ret;
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int server_idx, query_idx;
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int server_idx, query_idx = -1;
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data_len = MIN(net_pkt_remaining_data(pkt), DNS_RESOLVER_MAX_BUF_SIZE);
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@ -395,12 +401,6 @@ static int dns_read(struct dns_resolve_context *ctx,
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*/
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*dns_id = dns_unpack_header_id(dns_msg.msg);
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query_idx = get_slot_by_id(ctx, *dns_id);
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if (query_idx < 0) {
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ret = DNS_EAI_SYSTEM;
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goto quit;
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}
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if (dns_header_rcode(dns_msg.msg) == DNS_HEADER_REFUSED) {
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ret = DNS_EAI_FAIL;
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goto quit;
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@ -434,43 +434,12 @@ static int dns_read(struct dns_resolve_context *ctx,
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dns_msg.answer_offset = dns_msg.query_offset;
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}
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if (ctx->queries[query_idx].query_type == DNS_QUERY_TYPE_A) {
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if (net_sin(&info.ai_addr)->sin_family == AF_INET6) {
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ret = DNS_EAI_ADDRFAMILY;
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goto quit;
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}
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/* Because in mDNS the DNS id is set to 0 and must be ignored
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* on reply, we need to figure out the answer in order to find
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* the proper query. To simplify things, the normal DNS responses
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* are handled the same way.
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*/
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address_size = DNS_IPV4_LEN;
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addr = (u8_t *)&net_sin(&info.ai_addr)->sin_addr;
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info.ai_family = AF_INET;
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info.ai_addr.sa_family = AF_INET;
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info.ai_addrlen = sizeof(struct sockaddr_in);
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} else if (ctx->queries[query_idx].query_type == DNS_QUERY_TYPE_AAAA) {
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if (net_sin6(&info.ai_addr)->sin6_family == AF_INET) {
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ret = DNS_EAI_ADDRFAMILY;
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goto quit;
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}
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/* We cannot resolve IPv6 address if IPv6 is disabled. The reason
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* being that "struct sockaddr" does not have enough space for
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* IPv6 address in that case.
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*/
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#if defined(CONFIG_NET_IPV6)
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address_size = DNS_IPV6_LEN;
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addr = (u8_t *)&net_sin6(&info.ai_addr)->sin6_addr;
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info.ai_family = AF_INET6;
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info.ai_addr.sa_family = AF_INET6;
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info.ai_addrlen = sizeof(struct sockaddr_in6);
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#else
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ret = DNS_EAI_FAMILY;
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goto quit;
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#endif
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} else {
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ret = DNS_EAI_FAMILY;
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goto quit;
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}
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/* while loop to traverse the response */
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answer_ptr = DNS_QUERY_POS;
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items = 0;
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server_idx = 0;
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@ -483,6 +452,66 @@ static int dns_read(struct dns_resolve_context *ctx,
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switch (dns_msg.response_type) {
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case DNS_RESPONSE_IP:
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if (query_idx >= 0) {
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goto query_known;
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}
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query_name = dns_msg.msg + dns_msg.query_offset;
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/* Add \0 and query type (A or AAAA) to the hash */
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*query_hash = crc16_ansi(query_name,
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strlen(query_name) + 1 + 2);
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query_idx = get_slot_by_id(ctx, *dns_id, *query_hash);
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if (query_idx < 0) {
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ret = DNS_EAI_SYSTEM;
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goto quit;
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}
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if (ctx->queries[query_idx].query_type ==
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DNS_QUERY_TYPE_A) {
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if (net_sin(&info.ai_addr)->sin_family ==
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AF_INET6) {
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ret = DNS_EAI_ADDRFAMILY;
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goto quit;
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}
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address_size = DNS_IPV4_LEN;
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addr = (u8_t *)&net_sin(&info.ai_addr)->
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sin_addr;
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info.ai_family = AF_INET;
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info.ai_addr.sa_family = AF_INET;
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info.ai_addrlen = sizeof(struct sockaddr_in);
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} else if (ctx->queries[query_idx].query_type ==
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DNS_QUERY_TYPE_AAAA) {
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if (net_sin6(&info.ai_addr)->sin6_family ==
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AF_INET) {
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ret = DNS_EAI_ADDRFAMILY;
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goto quit;
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}
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/* We cannot resolve IPv6 address if IPv6 is
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* disabled. The reason being that
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* "struct sockaddr" does not have enough space
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* for IPv6 address in that case.
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*/
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#if defined(CONFIG_NET_IPV6)
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address_size = DNS_IPV6_LEN;
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addr = (u8_t *)&net_sin6(&info.ai_addr)->
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sin6_addr;
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info.ai_family = AF_INET6;
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info.ai_addr.sa_family = AF_INET6;
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info.ai_addrlen = sizeof(struct sockaddr_in6);
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#else
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ret = DNS_EAI_FAMILY;
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goto quit;
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#endif
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} else {
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ret = DNS_EAI_FAMILY;
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goto quit;
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}
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if (dns_msg.response_length < address_size) {
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/* it seems this is a malformed message */
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ret = DNS_EAI_FAIL;
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@ -490,9 +519,9 @@ static int dns_read(struct dns_resolve_context *ctx,
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}
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src = dns_msg.msg + dns_msg.response_position;
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memcpy(addr, src, address_size);
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query_known:
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ctx->queries[query_idx].cb(DNS_EAI_INPROGRESS, &info,
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ctx->queries[query_idx].user_data);
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items++;
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@ -517,6 +546,21 @@ static int dns_read(struct dns_resolve_context *ctx,
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server_idx++;
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}
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if (query_idx < 0) {
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/* If the query_idx is still unknown, try to get it here
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* and hope it is found.
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*/
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query_name = dns_msg.msg + dns_msg.query_offset;
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*query_hash = crc16_ansi(query_name,
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strlen(query_name) + 1 + 2);
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query_idx = get_slot_by_id(ctx, *dns_id, *query_hash);
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if (query_idx < 0) {
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ret = DNS_EAI_SYSTEM;
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goto quit;
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}
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}
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/* No IP addresses were found, so we take the last CNAME to generate
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* another query. Number of additional queries is controlled via Kconfig
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*/
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@ -556,8 +600,9 @@ static int dns_read(struct dns_resolve_context *ctx,
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return 0;
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finished:
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dns_resolve_cancel(ctx, *dns_id);
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dns_resolve_cancel_with_name(ctx, *dns_id,
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ctx->queries[query_idx].query,
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ctx->queries[query_idx].query_type);
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quit:
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net_pkt_unref(pkt);
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@ -574,6 +619,7 @@ static void cb_recv(struct net_context *net_ctx,
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struct dns_resolve_context *ctx = user_data;
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struct net_buf *dns_cname = NULL;
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struct net_buf *dns_data = NULL;
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u16_t query_hash = 0U;
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u16_t dns_id = 0U;
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int ret, i;
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@ -596,7 +642,7 @@ static void cb_recv(struct net_context *net_ctx,
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goto quit;
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}
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ret = dns_read(ctx, pkt, dns_data, &dns_id, dns_cname);
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ret = dns_read(ctx, pkt, dns_data, &dns_id, dns_cname, &query_hash);
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if (!ret) {
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/* We called the callback already in dns_read() if there
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* was no errors.
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@ -609,7 +655,7 @@ static void cb_recv(struct net_context *net_ctx,
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int failure = 0;
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int j;
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i = get_slot_by_id(ctx, dns_id);
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i = get_slot_by_id(ctx, dns_id, query_hash);
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if (i < 0) {
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goto free_buf;
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}
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@ -638,7 +684,7 @@ static void cb_recv(struct net_context *net_ctx,
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}
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quit:
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i = get_slot_by_id(ctx, dns_id);
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i = get_slot_by_id(ctx, dns_id, query_hash);
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if (i < 0) {
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goto free_buf;
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}
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@ -687,6 +733,13 @@ static int dns_write(struct dns_resolve_context *ctx,
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return -EINVAL;
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}
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/* Add \0 and query type (A or AAAA) to the hash. Note that
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* the dns_qname->len contains the length of \0
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*/
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ctx->queries[query_idx].query_hash =
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crc16_ansi(dns_data->data + DNS_MSG_HEADER_SIZE,
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dns_qname->len + 2);
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if (IS_ENABLED(CONFIG_NET_IPV6) &&
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net_context_get_family(net_ctx) == AF_INET6) {
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net_context_set_ipv6_hop_limit(net_ctx, hop_limit);
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@ -707,14 +760,6 @@ static int dns_write(struct dns_resolve_context *ctx,
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server_addr_len = sizeof(struct sockaddr_in6);
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}
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ret = net_context_sendto(net_ctx, dns_data->data, dns_data->len,
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server, server_addr_len, NULL,
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K_NO_WAIT, NULL);
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if (ret < 0) {
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NET_DBG("Cannot send query (%d)", ret);
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return ret;
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}
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ret = k_delayed_work_submit(&ctx->queries[query_idx].timer,
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ctx->queries[query_idx].timeout);
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if (ret < 0) {
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@ -725,25 +770,38 @@ static int dns_write(struct dns_resolve_context *ctx,
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return ret;
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}
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NET_DBG("[%u] submitting work to server idx %d for id %u "
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"timeout %u",
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"hash %u timeout %u",
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query_idx, server_idx, dns_id,
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ctx->queries[query_idx].query_hash,
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ctx->queries[query_idx].timeout);
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ret = net_context_sendto(net_ctx, dns_data->data, dns_data->len,
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server, server_addr_len, NULL,
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K_NO_WAIT, NULL);
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if (ret < 0) {
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NET_DBG("Cannot send query (%d)", ret);
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return ret;
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}
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return 0;
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}
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int dns_resolve_cancel(struct dns_resolve_context *ctx, u16_t dns_id)
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static int dns_resolve_cancel_with_hash(struct dns_resolve_context *ctx,
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u16_t dns_id,
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u16_t query_hash,
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const char *query_name)
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{
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int i;
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i = get_slot_by_id(ctx, dns_id);
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if (i < 0) {
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i = get_slot_by_id(ctx, dns_id, query_hash);
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if (i < 0 || !ctx->queries[i].cb) {
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return -ENOENT;
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}
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NET_DBG("Cancelling DNS req %u", dns_id);
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NET_DBG("Cancelling DNS req %u (name %s type %d hash %u)", dns_id,
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log_strdup(query_name), ctx->queries[i].query_type,
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query_hash);
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if (k_delayed_work_remaining_get(&ctx->queries[i].timer) > 0) {
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k_delayed_work_cancel(&ctx->queries[i].timer);
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@ -755,14 +813,71 @@ int dns_resolve_cancel(struct dns_resolve_context *ctx, u16_t dns_id)
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return 0;
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}
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int dns_resolve_cancel_with_name(struct dns_resolve_context *ctx,
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u16_t dns_id,
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const char *query_name,
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enum dns_query_type query_type)
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{
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u16_t query_hash = 0;
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if (query_name) {
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struct net_buf *buf;
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u16_t len;
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int ret;
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/* Use net_buf as a temporary buffer to store the packed
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* DNS name.
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*/
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buf = net_buf_alloc(&dns_msg_pool, ctx->buf_timeout);
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if (!buf) {
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return -ENOMEM;
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}
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ret = dns_msg_pack_qname(&len, buf->data, buf->size,
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query_name);
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if (ret >= 0) {
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/* If the query string + \0 + query type (A or AAAA)
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* does not fit the tmp buf, then bail out
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*/
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if ((len + 2) > buf->size) {
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net_buf_unref(buf);
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return -ENOMEM;
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}
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net_buf_add(buf, len);
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net_buf_add_be16(buf, query_type);
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query_hash = crc16_ansi(buf->data, len + 2);
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}
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net_buf_unref(buf);
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if (ret < 0) {
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return ret;
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}
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}
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return dns_resolve_cancel_with_hash(ctx, dns_id, query_hash,
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query_name);
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}
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int dns_resolve_cancel(struct dns_resolve_context *ctx, u16_t dns_id)
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{
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return dns_resolve_cancel_with_name(ctx, dns_id, NULL, 0);
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}
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static void query_timeout(struct k_work *work)
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{
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struct dns_pending_query *pending_query =
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CONTAINER_OF(work, struct dns_pending_query, timer);
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NET_DBG("Query timeout DNS req %u", pending_query->id);
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NET_DBG("Query timeout DNS req %u type %d hash %u", pending_query->id,
|
||||
pending_query->query_type, pending_query->query_hash);
|
||||
|
||||
dns_resolve_cancel(pending_query->ctx, pending_query->id);
|
||||
(void)dns_resolve_cancel_with_hash(pending_query->ctx,
|
||||
pending_query->id,
|
||||
pending_query->query_hash,
|
||||
pending_query->query);
|
||||
}
|
||||
|
||||
int dns_resolve_name(struct dns_resolve_context *ctx,
|
||||
|
|
@ -853,6 +968,7 @@ try_resolve:
|
|||
ctx->queries[i].query_type = type;
|
||||
ctx->queries[i].user_data = user_data;
|
||||
ctx->queries[i].ctx = ctx;
|
||||
ctx->queries[i].query_hash = 0;
|
||||
|
||||
k_delayed_work_init(&ctx->queries[i].timer, query_timeout);
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue