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esp-protocols/components/mdns/mdns_utils.c
David Cermak bed116d98b feat(mdns): Refactor mdns library (stage #1) 
The MDNS component has been refactored from a single monolithic file mdns.c
into a set of focused modules with clear responsibilities.
This restructuring maintains the same functionality while improving code organization,
maintainability, and testability.
In the stage#2 we will focus on module based tests
In the stage#3 we will focus on small scale refators and optimizations
2025-11-25 17:30:27 +01:00

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/*
* SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <string.h>
#include "sdkconfig.h"
#include "mdns_private.h"
#include "mdns_mem_caps.h"
#include "esp_log.h"
#include "mdns_utils.h"
#include "mdns_responder.h"
static const char *TAG = "mdns_utils";
static const char *MDNS_DEFAULT_DOMAIN = "local";
static const char *MDNS_SUB_STR = "_sub";
const uint8_t *mdns_utils_read_fqdn(const uint8_t *packet, const uint8_t *start, mdns_name_t *name, char *buf, size_t packet_len)
{
size_t index = 0;
const uint8_t *packet_end = packet + packet_len;
while (start + index < packet_end && start[index]) {
if (name->parts == 4) {
name->invalid = true;
}
uint8_t len = start[index++];
if (len < 0xC0) {
if (len > 63) {
//length can not be more than 63
return NULL;
}
uint8_t i;
for (i = 0; i < len; i++) {
if (start + index >= packet_end) {
return NULL;
}
buf[i] = start[index++];
}
buf[len] = '\0';
if (name->parts == 1 && buf[0] != '_'
&& (strcasecmp(buf, MDNS_DEFAULT_DOMAIN) != 0)
&& (strcasecmp(buf, "arpa") != 0)
#ifndef CONFIG_MDNS_RESPOND_REVERSE_QUERIES
&& (strcasecmp(buf, "ip6") != 0)
&& (strcasecmp(buf, "in-addr") != 0)
#endif
) {
strlcat(name->host, ".", sizeof(name->host));
strlcat(name->host, buf, sizeof(name->host));
} else if (strcasecmp(buf, MDNS_SUB_STR) == 0) {
name->sub = 1;
} else if (!name->invalid) {
char *mdns_name_ptrs[] = {name->host, name->service, name->proto, name->domain};
memcpy(mdns_name_ptrs[name->parts++], buf, len + 1);
}
} else {
size_t address = (((uint16_t)len & 0x3F) << 8) | start[index++];
if ((packet + address) >= start) {
//reference address can not be after where we are
return NULL;
}
if (mdns_utils_read_fqdn(packet, packet + address, name, buf, packet_len)) {
return start + index;
}
return NULL;
}
}
return start + index + 1;
}
const uint8_t *mdns_utils_parse_fqdn(const uint8_t *packet, const uint8_t *start, mdns_name_t *name, size_t packet_len)
{
name->parts = 0;
name->sub = 0;
name->host[0] = 0;
name->service[0] = 0;
name->proto[0] = 0;
name->domain[0] = 0;
name->invalid = false;
static char buf[MDNS_NAME_BUF_LEN];
const uint8_t *next_data = (uint8_t *) mdns_utils_read_fqdn(packet, start, name, buf, packet_len);
if (!next_data) {
return 0;
}
if (!name->parts || name->invalid) {
return next_data;
}
if (name->parts == 3) {
memmove((uint8_t *)name + (MDNS_NAME_BUF_LEN), (uint8_t *)name, 3 * (MDNS_NAME_BUF_LEN));
name->host[0] = 0;
} else if (name->parts == 2) {
memmove((uint8_t *)(name->domain), (uint8_t *)(name->service), (MDNS_NAME_BUF_LEN));
name->service[0] = 0;
name->proto[0] = 0;
}
if (strcasecmp(name->domain, MDNS_DEFAULT_DOMAIN) == 0 || strcasecmp(name->domain, "arpa") == 0) {
return next_data;
}
name->invalid = true; // mark the current name invalid, but continue with other question
return next_data;
}
bool mdns_utils_hostname_is_ours(const char *hostname)
{
if (!mdns_utils_str_null_or_empty(mdns_priv_get_global_hostname()) &&
strcasecmp(hostname, mdns_priv_get_global_hostname()) == 0) {
return true;
}
mdns_host_item_t *host = mdns_priv_get_hosts();
while (host != NULL) {
if (strcasecmp(hostname, host->hostname) == 0) {
return true;
}
host = host->next;
}
return false;
}
bool mdns_utils_service_match(const mdns_service_t *srv, const char *service, const char *proto,
const char *hostname)
{
if (!service || !proto || !srv || !srv->hostname) {
return false;
}
return !strcasecmp(srv->service, service) && !strcasecmp(srv->proto, proto) &&
(mdns_utils_str_null_or_empty(hostname) || !strcasecmp(srv->hostname, hostname));
}
mdns_srv_item_t *mdns_utils_get_service_item(const char *service, const char *proto, const char *hostname)
{
mdns_srv_item_t *s = mdns_priv_get_services();
while (s) {
if (mdns_utils_service_match(s->service, service, proto, hostname)) {
return s;
}
s = s->next;
}
return NULL;
}
mdns_srv_item_t *mdns_utils_get_service_item_instance(const char *instance, const char *service, const char *proto,
const char *hostname)
{
mdns_srv_item_t *s = mdns_priv_get_services();
while (s) {
if (instance) {
if (mdns_utils_service_match_instance(s->service, instance, service, proto, hostname)) {
return s;
}
} else {
if (mdns_utils_service_match(s->service, service, proto, hostname)) {
return s;
}
}
s = s->next;
}
return NULL;
}
bool mdns_utils_service_match_instance(const mdns_service_t *srv, const char *instance, const char *service,
const char *proto, const char *hostname)
{
// service and proto must be supplied, if not this instance won't match
if (!service || !proto) {
return false;
}
// instance==NULL -> mdns_utils_instance_name_match() will check the default instance
// hostname==NULL -> matches if instance, service and proto matches
return !strcasecmp(srv->service, service) && mdns_utils_instance_name_match(srv->instance, instance) &&
!strcasecmp(srv->proto, proto) && (mdns_utils_str_null_or_empty(hostname) || !strcasecmp(srv->hostname, hostname));
}
static const char *get_default_instance_name(void)
{
const char* instance = mdns_priv_get_instance();
if (!mdns_utils_str_null_or_empty(instance)) {
return instance;
}
const char* host = mdns_priv_get_global_hostname();
if (!mdns_utils_str_null_or_empty(host)) {
return host;
}
return NULL;
}
/**
* @brief Get the service name of a service
*/
const char *mdns_utils_get_service_instance_name(const mdns_service_t *service)
{
if (service && !mdns_utils_str_null_or_empty(service->instance)) {
return service->instance;
}
return get_default_instance_name();
}
bool mdns_utils_instance_name_match(const char *lhs, const char *rhs)
{
if (lhs == NULL) {
lhs = get_default_instance_name();
}
if (rhs == NULL) {
rhs = get_default_instance_name();
}
return !strcasecmp(lhs, rhs);
}
mdns_ip_addr_t *mdns_utils_copy_address_list(const mdns_ip_addr_t *address_list)
{
mdns_ip_addr_t *head = NULL;
mdns_ip_addr_t *tail = NULL;
while (address_list != NULL) {
mdns_ip_addr_t *addr = (mdns_ip_addr_t *)mdns_mem_malloc(sizeof(mdns_ip_addr_t));
if (addr == NULL) {
HOOK_MALLOC_FAILED;
mdns_utils_free_address_list(head);
return NULL;
}
addr->addr = address_list->addr;
addr->next = NULL;
if (head == NULL) {
head = addr;
tail = addr;
} else {
tail->next = addr;
tail = tail->next;
}
address_list = address_list->next;
}
return head;
}
void mdns_utils_free_address_list(mdns_ip_addr_t *address_list)
{
while (address_list != NULL) {
mdns_ip_addr_t *next = address_list->next;
mdns_mem_free(address_list);
address_list = next;
}
}
#ifdef CONFIG_LWIP_IPV6
bool mdns_utils_ipv6_address_is_zero(esp_ip6_addr_t ip6)
{
uint8_t i;
uint8_t *data = (uint8_t *)ip6.addr;
for (i = 0; i < MDNS_UTILS_SIZEOF_IP6_ADDR; i++) {
if (data[i]) {
return false;
}
}
return true;
}
#endif /* CONFIG_LWIP_IPV6 */
uint8_t mdns_utils_append_u16(uint8_t *packet, uint16_t *index, uint16_t value)
{
if ((*index + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
mdns_utils_append_u8(packet, index, (value >> 8) & 0xFF);
mdns_utils_append_u8(packet, index, value & 0xFF);
return 2;
}
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