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resolve.c
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resolve.c
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/** @file
* @brief DNS resolve API
*
* An API for applications to do DNS query.
*/
/*
* Copyright (c) 2017 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(net_dns_resolve, CONFIG_DNS_RESOLVER_LOG_LEVEL);
#include <zephyr/types.h>
#include <zephyr/random/random.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <zephyr/sys/crc.h>
#include <zephyr/net/net_ip.h>
#include <zephyr/net/net_pkt.h>
#include <zephyr/net/net_mgmt.h>
#include <zephyr/net/dns_resolve.h>
#include "dns_pack.h"
#include "dns_internal.h"
#define DNS_SERVER_COUNT CONFIG_DNS_RESOLVER_MAX_SERVERS
#define SERVER_COUNT (DNS_SERVER_COUNT + DNS_MAX_MCAST_SERVERS)
#define MDNS_IPV4_ADDR "224.0.0.251:5353"
#define MDNS_IPV6_ADDR "[ff02::fb]:5353"
#define LLMNR_IPV4_ADDR "224.0.0.252:5355"
#define LLMNR_IPV6_ADDR "[ff02::1:3]:5355"
#define DNS_BUF_TIMEOUT K_MSEC(500) /* ms */
/* RFC 1035, 3.1. Name space definitions
* To simplify implementations, the total length of a domain name (i.e.,
* label octets and label length octets) is restricted to 255 octets or
* less.
*/
#define DNS_MAX_NAME_LEN 255
#define DNS_QUERY_MAX_SIZE (DNS_MSG_HEADER_SIZE + DNS_MAX_NAME_LEN + \
DNS_QTYPE_LEN + DNS_QCLASS_LEN)
/* This value is recommended by RFC 1035 */
#define DNS_RESOLVER_MAX_BUF_SIZE 512
#define DNS_RESOLVER_MIN_BUF 1
#define DNS_RESOLVER_BUF_CTR (DNS_RESOLVER_MIN_BUF + \
CONFIG_DNS_RESOLVER_ADDITIONAL_BUF_CTR)
/* Compressed RR uses a pointer to another RR. So, min size is 12 bytes without
* considering RR payload.
* See https://tools.ietf.org/html/rfc1035#section-4.1.4
*/
#define DNS_ANSWER_PTR_LEN 12
/* See dns_unpack_answer, and also see:
* https://tools.ietf.org/html/rfc1035#section-4.1.2
*/
#define DNS_QUERY_POS 0x0c
#define DNS_IPV4_LEN sizeof(struct in_addr)
#define DNS_IPV6_LEN sizeof(struct in6_addr)
NET_BUF_POOL_DEFINE(dns_msg_pool, DNS_RESOLVER_BUF_CTR,
DNS_RESOLVER_MAX_BUF_SIZE, 0, NULL);
NET_BUF_POOL_DEFINE(dns_qname_pool, DNS_RESOLVER_BUF_CTR, DNS_MAX_NAME_LEN,
0, NULL);
static struct dns_resolve_context dns_default_ctx;
/* Must be invoked with context lock held */
static int dns_write(struct dns_resolve_context *ctx,
int server_idx,
int query_idx,
struct net_buf *dns_data,
struct net_buf *dns_qname,
int hop_limit);
static bool server_is_mdns(sa_family_t family, struct sockaddr *addr)
{
if (family == AF_INET) {
if (net_ipv4_is_addr_mcast(&net_sin(addr)->sin_addr) &&
net_sin(addr)->sin_addr.s4_addr[3] == 251U) {
return true;
}
return false;
}
if (family == AF_INET6) {
if (net_ipv6_is_addr_mcast(&net_sin6(addr)->sin6_addr) &&
net_sin6(addr)->sin6_addr.s6_addr[15] == 0xfb) {
return true;
}
return false;
}
return false;
}
static bool server_is_llmnr(sa_family_t family, struct sockaddr *addr)
{
if (family == AF_INET) {
if (net_ipv4_is_addr_mcast(&net_sin(addr)->sin_addr) &&
net_sin(addr)->sin_addr.s4_addr[3] == 252U) {
return true;
}
return false;
}
if (family == AF_INET6) {
if (net_ipv6_is_addr_mcast(&net_sin6(addr)->sin6_addr) &&
net_sin6(addr)->sin6_addr.s6_addr[15] == 0x03) {
return true;
}
return false;
}
return false;
}
static void dns_postprocess_server(struct dns_resolve_context *ctx, int idx)
{
struct sockaddr *addr = &ctx->servers[idx].dns_server;
if (addr->sa_family == AF_INET) {
ctx->servers[idx].is_mdns = server_is_mdns(AF_INET, addr);
if (!ctx->servers[idx].is_mdns) {
ctx->servers[idx].is_llmnr =
server_is_llmnr(AF_INET, addr);
}
if (net_sin(addr)->sin_port == 0U) {
if (IS_ENABLED(CONFIG_MDNS_RESOLVER) &&
ctx->servers[idx].is_mdns) {
/* We only use 5353 as a default port
* if mDNS support is enabled. User can
* override this by defining the port
* in config file.
*/
net_sin(addr)->sin_port = htons(5353);
} else if (IS_ENABLED(CONFIG_LLMNR_RESOLVER) &&
ctx->servers[idx].is_llmnr) {
/* We only use 5355 as a default port
* if LLMNR support is enabled. User can
* override this by defining the port
* in config file.
*/
net_sin(addr)->sin_port = htons(5355);
} else {
net_sin(addr)->sin_port = htons(53);
}
}
} else {
ctx->servers[idx].is_mdns = server_is_mdns(AF_INET6, addr);
if (!ctx->servers[idx].is_mdns) {
ctx->servers[idx].is_llmnr =
server_is_llmnr(AF_INET6, addr);
}
if (net_sin6(addr)->sin6_port == 0U) {
if (IS_ENABLED(CONFIG_MDNS_RESOLVER) &&
ctx->servers[idx].is_mdns) {
net_sin6(addr)->sin6_port = htons(5353);
} else if (IS_ENABLED(CONFIG_LLMNR_RESOLVER) &&
ctx->servers[idx].is_llmnr) {
net_sin6(addr)->sin6_port = htons(5355);
} else {
net_sin6(addr)->sin6_port = htons(53);
}
}
}
}
/* Must be invoked with context lock held */
static int dns_resolve_init_locked(struct dns_resolve_context *ctx,
const char *servers[],
const struct sockaddr *servers_sa[])
{
#if defined(CONFIG_NET_IPV6)
struct sockaddr_in6 local_addr6 = {
.sin6_family = AF_INET6,
.sin6_port = 0,
};
#endif
#if defined(CONFIG_NET_IPV4)
struct sockaddr_in local_addr4 = {
.sin_family = AF_INET,
.sin_port = 0,
};
#endif
struct sockaddr *local_addr = NULL;
socklen_t addr_len = 0;
int i = 0, idx = 0;
struct net_if *iface;
int ret, count;
if (!ctx) {
return -ENOENT;
}
if (ctx->state != DNS_RESOLVE_CONTEXT_INACTIVE) {
ret = -ENOTEMPTY;
goto fail;
}
if (servers) {
for (i = 0; idx < SERVER_COUNT && servers[i]; i++) {
struct sockaddr *addr = &ctx->servers[idx].dns_server;
(void)memset(addr, 0, sizeof(*addr));
ret = net_ipaddr_parse(servers[i], strlen(servers[i]),
addr);
if (!ret) {
continue;
}
dns_postprocess_server(ctx, idx);
NET_DBG("[%d] %s%s%s", i, servers[i],
IS_ENABLED(CONFIG_MDNS_RESOLVER) ?
(ctx->servers[i].is_mdns ? " mDNS" : "") : "",
IS_ENABLED(CONFIG_LLMNR_RESOLVER) ?
(ctx->servers[i].is_llmnr ?
" LLMNR" : "") : "");
idx++;
}
}
if (servers_sa) {
for (i = 0; idx < SERVER_COUNT && servers_sa[i]; i++) {
memcpy(&ctx->servers[idx].dns_server, servers_sa[i],
sizeof(ctx->servers[idx].dns_server));
dns_postprocess_server(ctx, idx);
idx++;
}
}
for (i = 0, count = 0;
i < SERVER_COUNT && ctx->servers[i].dns_server.sa_family; i++) {
if (ctx->servers[i].dns_server.sa_family == AF_INET6) {
#if defined(CONFIG_NET_IPV6)
local_addr = (struct sockaddr *)&local_addr6;
addr_len = sizeof(struct sockaddr_in6);
if (IS_ENABLED(CONFIG_MDNS_RESOLVER) &&
ctx->servers[i].is_mdns) {
local_addr6.sin6_port = htons(5353);
}
#else
continue;
#endif
}
if (ctx->servers[i].dns_server.sa_family == AF_INET) {
#if defined(CONFIG_NET_IPV4)
local_addr = (struct sockaddr *)&local_addr4;
addr_len = sizeof(struct sockaddr_in);
if (IS_ENABLED(CONFIG_MDNS_RESOLVER) &&
ctx->servers[i].is_mdns) {
local_addr4.sin_port = htons(5353);
}
#else
continue;
#endif
}
if (!local_addr) {
NET_DBG("Local address not set");
ret = -EAFNOSUPPORT;
goto fail;
}
ret = net_context_get(ctx->servers[i].dns_server.sa_family,
SOCK_DGRAM, IPPROTO_UDP,
&ctx->servers[i].net_ctx);
if (ret < 0) {
NET_DBG("Cannot get net_context (%d)", ret);
goto fail;
}
ret = net_context_bind(ctx->servers[i].net_ctx,
local_addr, addr_len);
if (ret < 0) {
NET_DBG("Cannot bind DNS context (%d)", ret);
goto fail;
}
iface = net_context_get_iface(ctx->servers[i].net_ctx);
if (IS_ENABLED(CONFIG_NET_MGMT_EVENT_INFO)) {
net_mgmt_event_notify_with_info(
NET_EVENT_DNS_SERVER_ADD,
iface, (void *)&ctx->servers[i].dns_server,
sizeof(struct sockaddr));
} else {
net_mgmt_event_notify(NET_EVENT_DNS_SERVER_ADD, iface);
}
#if defined(CONFIG_NET_IPV6)
local_addr6.sin6_port = 0;
#endif
#if defined(CONFIG_NET_IPV4)
local_addr4.sin_port = 0;
#endif
count++;
}
if (count == 0) {
/* No servers defined */
NET_DBG("No DNS servers defined.");
ret = -EINVAL;
goto fail;
}
ctx->state = DNS_RESOLVE_CONTEXT_ACTIVE;
ctx->buf_timeout = DNS_BUF_TIMEOUT;
ret = 0;
fail:
return ret;
}
int dns_resolve_init(struct dns_resolve_context *ctx, const char *servers[],
const struct sockaddr *servers_sa[])
{
if (!ctx) {
return -ENOENT;
}
(void)memset(ctx, 0, sizeof(*ctx));
(void)k_mutex_init(&ctx->lock);
ctx->state = DNS_RESOLVE_CONTEXT_INACTIVE;
/* As this function is called only once during system init, there is no
* reason to acquire lock.
*/
return dns_resolve_init_locked(ctx, servers, servers_sa);
}
/* Check whether a slot is available for use, or optionally whether it can be
* reclaimed.
*
* @param pending_query the query slot in question
*
* @param reclaim_if_available if the slot is marked in use, but the query has
* been completed and the work item is no longer pending, complete the release
* of the slot.
*
* @return true if and only if the slot can be used for a new query.
*/
static inline bool check_query_active(struct dns_pending_query *pending_query,
bool reclaim_if_available)
{
int ret = false;
if (pending_query->cb != NULL) {
ret = true;
if (reclaim_if_available
&& pending_query->query == NULL
&& k_work_delayable_busy_get(&pending_query->timer) == 0) {
pending_query->cb = NULL;
ret = false;
}
}
return ret;
}
/* Must be invoked with context lock held */
static inline int get_cb_slot(struct dns_resolve_context *ctx)
{
int i;
for (i = 0; i < CONFIG_DNS_NUM_CONCUR_QUERIES; i++) {
if (!check_query_active(&ctx->queries[i], true)) {
return i;
}
}
return -ENOENT;
}
/* Invoke the callback associated with a query slot, if still relevant.
*
* Must be invoked with context lock held.
*
* @param status the query status value
* @param info the query result structure
* @param pending_query the query slot that will provide the callback
**/
static inline void invoke_query_callback(int status,
struct dns_addrinfo *info,
struct dns_pending_query *pending_query)
{
/* Only notify if the slot is neither released nor in the process of
* being released.
*/
if (pending_query->query != NULL && pending_query->cb != NULL) {
pending_query->cb(status, info, pending_query->user_data);
}
}
/* Release a query slot reserved by get_cb_slot().
*
* Must be invoked with context lock held.
*
* @param pending_query the query slot to be released
*/
static void release_query(struct dns_pending_query *pending_query)
{
int busy = k_work_cancel_delayable(&pending_query->timer);
/* If the work item is no longer pending we're done. */
if (busy == 0) {
/* All done. */
pending_query->cb = NULL;
} else {
/* Work item is still pending. Set a secondary condition that
* can be checked by get_cb_slot() to complete release of the
* slot once the work item has been confirmed to be completed.
*/
pending_query->query = NULL;
}
}
/* Must be invoked with context lock held */
static inline int get_slot_by_id(struct dns_resolve_context *ctx,
uint16_t dns_id,
uint16_t query_hash)
{
int i;
for (i = 0; i < CONFIG_DNS_NUM_CONCUR_QUERIES; i++) {
if (check_query_active(&ctx->queries[i], false) &&
ctx->queries[i].id == dns_id &&
(query_hash == 0 ||
ctx->queries[i].query_hash == query_hash)) {
return i;
}
}
return -ENOENT;
}
/* Unit test needs to be able to call this function */
#if !defined(CONFIG_NET_TEST)
static
#endif
int dns_validate_msg(struct dns_resolve_context *ctx,
struct dns_msg_t *dns_msg,
uint16_t *dns_id,
int *query_idx,
struct net_buf *dns_cname,
uint16_t *query_hash)
{
struct dns_addrinfo info = { 0 };
uint32_t ttl; /* RR ttl, so far it is not passed to caller */
uint8_t *src, *addr;
const char *query_name;
int address_size;
/* index that points to the current answer being analyzed */
int answer_ptr;
int items;
int server_idx;
int ret = 0;
/* Make sure that we can read DNS id, flags and rcode */
if (dns_msg->msg_size < (sizeof(*dns_id) + sizeof(uint16_t))) {
ret = DNS_EAI_FAIL;
goto quit;
}
/* The dns_unpack_response_header() has design flaw as it expects
* dns id to be given instead of returning the id to the caller.
* In our case we would like to get it returned instead so that we
* can match the DNS query that we sent. When dns_read() is called,
* we do not know what the DNS id is yet.
*/
*dns_id = dns_unpack_header_id(dns_msg->msg);
if (dns_header_rcode(dns_msg->msg) == DNS_HEADER_REFUSED) {
ret = DNS_EAI_FAIL;
goto quit;
}
/* We might receive a query while we are waiting for a response, in that
* case we just ignore the query instead of making the resolving fail.
*/
if (dns_header_qr(dns_msg->msg) == DNS_QUERY) {
ret = 0;
goto quit;
}
ret = dns_unpack_response_header(dns_msg, *dns_id);
if (ret < 0) {
ret = DNS_EAI_FAIL;
goto quit;
}
if (dns_header_qdcount(dns_msg->msg) != 1) {
/* For mDNS (when dns_id == 0) the query count is 0 */
if (*dns_id > 0) {
ret = DNS_EAI_FAIL;
goto quit;
}
}
ret = dns_unpack_response_query(dns_msg);
if (ret < 0) {
/* Check mDNS like above */
if (*dns_id > 0) {
ret = DNS_EAI_FAIL;
goto quit;
}
/* mDNS responses to do not have the query part so the
* answer starts immediately after the header.
*/
dns_msg->answer_offset = dns_msg->query_offset;
}
/* Because in mDNS the DNS id is set to 0 and must be ignored
* on reply, we need to figure out the answer in order to find
* the proper query. To simplify things, the normal DNS responses
* are handled the same way.
*/
answer_ptr = DNS_QUERY_POS;
items = 0;
server_idx = 0;
enum dns_rr_type answer_type = DNS_RR_TYPE_INVALID;
while (server_idx < dns_header_ancount(dns_msg->msg)) {
ret = dns_unpack_answer(dns_msg, answer_ptr, &ttl,
&answer_type);
if (ret < 0) {
ret = DNS_EAI_FAIL;
goto quit;
}
switch (dns_msg->response_type) {
case DNS_RESPONSE_IP:
if (*query_idx >= 0) {
goto query_known;
}
query_name = dns_msg->msg + dns_msg->query_offset;
/* Add \0 and query type (A or AAAA) to the hash */
*query_hash = crc16_ansi(query_name,
strlen(query_name) + 1 + 2);
*query_idx = get_slot_by_id(ctx, *dns_id, *query_hash);
if (*query_idx < 0) {
ret = DNS_EAI_SYSTEM;
goto quit;
}
query_known:
if (ctx->queries[*query_idx].query_type ==
DNS_QUERY_TYPE_A) {
if (answer_type != DNS_RR_TYPE_A) {
ret = DNS_EAI_ADDRFAMILY;
goto quit;
}
address_size = DNS_IPV4_LEN;
addr = (uint8_t *)&net_sin(&info.ai_addr)->
sin_addr;
info.ai_family = AF_INET;
info.ai_addr.sa_family = AF_INET;
info.ai_addrlen = sizeof(struct sockaddr_in);
} else if (ctx->queries[*query_idx].query_type ==
DNS_QUERY_TYPE_AAAA) {
if (answer_type != DNS_RR_TYPE_AAAA) {
ret = DNS_EAI_ADDRFAMILY;
goto quit;
}
/* We cannot resolve IPv6 address if IPv6 is
* disabled. The reason being that
* "struct sockaddr" does not have enough space
* for IPv6 address in that case.
*/
#if defined(CONFIG_NET_IPV6)
address_size = DNS_IPV6_LEN;
addr = (uint8_t *)&net_sin6(&info.ai_addr)->
sin6_addr;
info.ai_family = AF_INET6;
info.ai_addr.sa_family = AF_INET6;
info.ai_addrlen = sizeof(struct sockaddr_in6);
#else
ret = DNS_EAI_FAMILY;
goto quit;
#endif
} else {
ret = DNS_EAI_FAMILY;
goto quit;
}
if (dns_msg->response_length < address_size) {
/* it seems this is a malformed message */
ret = DNS_EAI_FAIL;
goto quit;
}
if ((dns_msg->response_position + address_size) >
dns_msg->msg_size) {
/* Too short message */
ret = DNS_EAI_FAIL;
goto quit;
}
src = dns_msg->msg + dns_msg->response_position;
memcpy(addr, src, address_size);
invoke_query_callback(DNS_EAI_INPROGRESS, &info,
&ctx->queries[*query_idx]);
items++;
break;
case DNS_RESPONSE_CNAME_NO_IP:
/* Instead of using the QNAME at DNS_QUERY_POS,
* we will use this CNAME
*/
answer_ptr = dns_msg->response_position;
break;
default:
ret = DNS_EAI_FAIL;
goto quit;
}
/* Update the answer offset to point to the next RR (answer) */
dns_msg->answer_offset += dns_msg->response_position -
dns_msg->answer_offset;
dns_msg->answer_offset += dns_msg->response_length;
server_idx++;
}
if (*query_idx < 0) {
/* If the query_idx is still unknown, try to get it here
* and hope it is found.
*/
query_name = dns_msg->msg + dns_msg->query_offset;
*query_hash = crc16_ansi(query_name,
strlen(query_name) + 1 + 2);
*query_idx = get_slot_by_id(ctx, *dns_id, *query_hash);
if (*query_idx < 0) {
ret = DNS_EAI_SYSTEM;
goto quit;
}
}
/* No IP addresses were found, so we take the last CNAME to generate
* another query. Number of additional queries is controlled via Kconfig
*/
if (items == 0) {
if (dns_msg->response_type == DNS_RESPONSE_CNAME_NO_IP) {
uint16_t pos = dns_msg->response_position;
/* The dns_cname should always be set. As a special
* case, it might not be set for unit tests that call
* this function directly.
*/
if (dns_cname) {
ret = dns_copy_qname(dns_cname->data,
&dns_cname->len,
dns_cname->size,
dns_msg, pos);
if (ret < 0) {
ret = DNS_EAI_SYSTEM;
goto quit;
}
}
ret = DNS_EAI_AGAIN;
goto quit;
}
}
if (items == 0) {
ret = DNS_EAI_NODATA;
} else {
ret = DNS_EAI_ALLDONE;
}
quit:
return ret;
}
/* Must be invoked with context lock held */
static int dns_read(struct dns_resolve_context *ctx,
struct net_pkt *pkt,
struct net_buf *dns_data,
uint16_t *dns_id,
struct net_buf *dns_cname,
uint16_t *query_hash)
{
/* Helper struct to track the dns msg received from the server */
struct dns_msg_t dns_msg;
int data_len;
int ret;
int query_idx = -1;
data_len = MIN(net_pkt_remaining_data(pkt), DNS_RESOLVER_MAX_BUF_SIZE);
/* TODO: Instead of this temporary copy, just use the net_pkt directly.
*/
ret = net_pkt_read(pkt, dns_data->data, data_len);
if (ret < 0) {
ret = DNS_EAI_MEMORY;
goto quit;
}
dns_msg.msg = dns_data->data;
dns_msg.msg_size = data_len;
ret = dns_validate_msg(ctx, &dns_msg, dns_id, &query_idx,
dns_cname, query_hash);
if (ret == DNS_EAI_AGAIN) {
goto finished;
}
if (ret < 0 || query_idx < 0 ||
query_idx > CONFIG_DNS_NUM_CONCUR_QUERIES) {
goto quit;
}
invoke_query_callback(ret, NULL, &ctx->queries[query_idx]);
/* Marks the end of the results */
release_query(&ctx->queries[query_idx]);
net_pkt_unref(pkt);
return 0;
finished:
dns_resolve_cancel_with_name(ctx, *dns_id,
ctx->queries[query_idx].query,
ctx->queries[query_idx].query_type);
quit:
net_pkt_unref(pkt);
return ret;
}
static void cb_recv(struct net_context *net_ctx,
struct net_pkt *pkt,
union net_ip_header *ip_hdr,
union net_proto_header *proto_hdr,
int status,
void *user_data)
{
struct dns_resolve_context *ctx = user_data;
struct net_buf *dns_cname = NULL;
struct net_buf *dns_data = NULL;
uint16_t query_hash = 0U;
uint16_t dns_id = 0U;
int ret, i;
ARG_UNUSED(net_ctx);
k_mutex_lock(&ctx->lock, K_FOREVER);
if (ctx->state != DNS_RESOLVE_CONTEXT_ACTIVE) {
goto unlock;
}
if (status) {
ret = DNS_EAI_SYSTEM;
goto quit;
}
dns_data = net_buf_alloc(&dns_msg_pool, ctx->buf_timeout);
if (!dns_data) {
ret = DNS_EAI_MEMORY;
goto quit;
}
dns_cname = net_buf_alloc(&dns_qname_pool, ctx->buf_timeout);
if (!dns_cname) {
ret = DNS_EAI_MEMORY;
goto quit;
}
ret = dns_read(ctx, pkt, dns_data, &dns_id, dns_cname, &query_hash);
if (!ret) {
/* We called the callback already in dns_read() if there
* was no errors.
*/
goto free_buf;
}
/* Query again if we got CNAME */
if (ret == DNS_EAI_AGAIN) {
int failure = 0;
int j;
i = get_slot_by_id(ctx, dns_id, query_hash);
if (i < 0) {
goto free_buf;
}
for (j = 0; j < SERVER_COUNT; j++) {
if (!ctx->servers[j].net_ctx) {
continue;
}
ret = dns_write(ctx, j, i, dns_data, dns_cname, 0);
if (ret < 0) {
failure++;
}
}
if (failure) {
NET_DBG("DNS cname query failed %d times", failure);
if (failure == j) {
ret = DNS_EAI_SYSTEM;
goto quit;
}
}
goto free_buf;
}
quit:
i = get_slot_by_id(ctx, dns_id, query_hash);
if (i < 0) {
goto free_buf;
}
invoke_query_callback(ret, NULL, &ctx->queries[i]);
/* Marks the end of the results */
release_query(&ctx->queries[i]);
free_buf:
if (dns_data) {
net_buf_unref(dns_data);
}
if (dns_cname) {
net_buf_unref(dns_cname);
}
unlock:
k_mutex_unlock(&ctx->lock);
}
/* Must be invoked with context lock held */
static int dns_write(struct dns_resolve_context *ctx,
int server_idx,
int query_idx,
struct net_buf *dns_data,
struct net_buf *dns_qname,
int hop_limit)
{
enum dns_query_type query_type;
struct net_context *net_ctx;
struct sockaddr *server;
int server_addr_len;
uint16_t dns_id;
int ret;
net_ctx = ctx->servers[server_idx].net_ctx;
server = &ctx->servers[server_idx].dns_server;
dns_id = ctx->queries[query_idx].id;
query_type = ctx->queries[query_idx].query_type;
ret = dns_msg_pack_query(dns_data->data, &dns_data->len, dns_data->size,
dns_qname->data, dns_qname->len, dns_id,
(enum dns_rr_type)query_type);
if (ret < 0) {
return -EINVAL;
}
/* Add \0 and query type (A or AAAA) to the hash. Note that
* the dns_qname->len contains the length of \0
*/
ctx->queries[query_idx].query_hash =
crc16_ansi(dns_data->data + DNS_MSG_HEADER_SIZE,
dns_qname->len + 2);
if (IS_ENABLED(CONFIG_NET_IPV6) &&
net_context_get_family(net_ctx) == AF_INET6 &&
hop_limit > 0) {
net_context_set_ipv6_hop_limit(net_ctx, hop_limit);
} else if (IS_ENABLED(CONFIG_NET_IPV4) &&
net_context_get_family(net_ctx) == AF_INET &&
hop_limit > 0) {
net_context_set_ipv4_ttl(net_ctx, hop_limit);
}
ret = net_context_recv(net_ctx, cb_recv, K_NO_WAIT, ctx);
if (ret < 0 && ret != -EALREADY) {
NET_DBG("Could not receive from socket (%d)", ret);
return ret;
}
if (server->sa_family == AF_INET) {
server_addr_len = sizeof(struct sockaddr_in);
} else {
server_addr_len = sizeof(struct sockaddr_in6);
}
ret = k_work_reschedule(&ctx->queries[query_idx].timer,
ctx->queries[query_idx].timeout);
if (ret < 0) {
NET_DBG("[%u] cannot submit work to server idx %d for id %u "
"ret %d", query_idx, server_idx, dns_id, ret);
return ret;
}
NET_DBG("[%u] submitting work to server idx %d for id %u "
"hash %u", query_idx, server_idx, dns_id,
ctx->queries[query_idx].query_hash);
ret = net_context_sendto(net_ctx, dns_data->data, dns_data->len,
server, server_addr_len, NULL,
K_NO_WAIT, NULL);
if (ret < 0) {
NET_DBG("Cannot send query (%d)", ret);
return ret;
}
return 0;
}
/* Must be invoked with context lock held */
static void dns_resolve_cancel_slot(struct dns_resolve_context *ctx, int slot)
{
invoke_query_callback(DNS_EAI_CANCELED, NULL, &ctx->queries[slot]);
release_query(&ctx->queries[slot]);
}
/* Must be invoked with context lock held */
static void dns_resolve_cancel_all(struct dns_resolve_context *ctx)
{
int i;
for (i = 0; i < CONFIG_DNS_NUM_CONCUR_QUERIES; i++) {
if (ctx->queries[i].cb && ctx->queries[i].query) {
dns_resolve_cancel_slot(ctx, i);
}
}
}
static int dns_resolve_cancel_with_hash(struct dns_resolve_context *ctx,
uint16_t dns_id,
uint16_t query_hash,
const char *query_name)
{
int ret = 0;
int i;
k_mutex_lock(&ctx->lock, K_FOREVER);
if (ctx->state == DNS_RESOLVE_CONTEXT_DEACTIVATING) {
/*
* Cancel is part of context "deactivating" process, so no need
* to do anything more.
*/
goto unlock;
}
i = get_slot_by_id(ctx, dns_id, query_hash);
if (i < 0) {
ret = -ENOENT;
goto unlock;
}
NET_DBG("Cancelling DNS req %u (name %s type %d hash %u)", dns_id,
query_name, ctx->queries[i].query_type,
query_hash);