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feat(mdns): Add support for IPv4 reverse query

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Partially addresses https://github.com/espressif/esp-protocols/issues/101
This commit is contained in:
David Cermak
2023-01-12 19:59:06 +01:00
parent 28813148b2
commit b87bef52e5
1 changed files with 103 additions and 17 deletions
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120
components/mdns/mdns.c
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@ -434,8 +434,7 @@ static const uint8_t *_mdns_read_fqdn(const uint8_t *packet, const uint8_t *star
if (name->parts == 1 && buf[0] != '_'
&& (strcasecmp(buf, MDNS_DEFAULT_DOMAIN) != 0)
&& (strcasecmp(buf, "arpa") != 0)
&& (strcasecmp(buf, "ip6") != 0)
&& (strcasecmp(buf, "in-addr") != 0)) {
&& (strcasecmp(buf, "ip6") != 0)) {
strlcat(name->host, ".", sizeof(name->host));
strlcat(name->host, buf, sizeof(name->host));
} else if (strcasecmp(buf, MDNS_SUB_STR) == 0) {
@ -680,7 +679,7 @@ search_next:
const uint8_t *content = _mdns_read_fqdn(packet, len_location, &name, buf, packet_len);
if (!content) {
//not a readable fqdn?
return 0;
goto search_next; // could be our unfinished fqdn, continue searching
}
if (name.parts == count) {
uint8_t i;
@ -1100,22 +1099,36 @@ static uint16_t _mdns_append_aaaa_record(uint8_t *packet, uint16_t *index, const
*/
static uint16_t _mdns_append_question(uint8_t *packet, uint16_t *index, mdns_out_question_t *q)
{
const char *str[4];
const char *str[6];
uint8_t str_index = 0;
uint8_t part_length;
if (q->host) {
str[str_index++] = q->host;
}
if (q->service) {
str[str_index++] = q->service;
}
if (q->proto) {
str[str_index++] = q->proto;
}
if (q->domain) {
str[str_index++] = q->domain;
if (q->host && strstr(q->host, "in-addr")) {
char * host = strdup(q->host);
char *rest = NULL;
for (char *p = strtok_r(host,".", &rest); p != NULL; p = strtok_r(NULL, ".", &rest)) {
str[str_index++] = p;
}
if (q->domain) {
str[str_index++] = q->domain;
}
} else {
if (q->host) {
str[str_index++] = q->host;
}
if (q->service) {
str[str_index++] = q->service;
}
if (q->proto) {
str[str_index++] = q->proto;
}
if (q->domain) {
str[str_index++] = q->domain;
}
}
part_length = _mdns_append_fqdn(packet, index, str, str_index, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
@ -1200,6 +1213,63 @@ static uint8_t _mdns_append_host_answer(uint8_t *packet, uint16_t *index, mdns_h
return num_records;
}
static uint16_t _mdns_append_rev_ptr_record(uint8_t * packet, uint16_t * index, const char* name, bool flush, bool bye)
{
const char * str[6];
int i = 0;
if (strstr(name, "in-addr") == NULL) {
return 0;
}
char * host = strdup(name);
char *rest = NULL;
for (char *p = strtok_r(host,".", &rest); p != NULL; p = strtok_r(NULL, ".", &rest)) {
str[i++] = p;
}
str[i++] = "arpa";
uint16_t record_length = 0;
uint8_t part_length;
part_length = _mdns_append_fqdn(packet, index, str, i, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_PTR, false, bye?0:MDNS_ANSWER_PTR_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
str[0] = _mdns_self_host.hostname;
str[1] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
_mdns_set_u16(packet, data_len_location, part_length);
record_length += part_length;
return record_length;
}
static uint8_t _mdns_append_reverse_ptr_record(uint8_t *packet, uint16_t *index, const char* name, bool flush, bool bye)
{
uint8_t appended_answers = 0;
if (_mdns_append_rev_ptr_record(packet, index, name, flush, bye) <= 0) {
return appended_answers;
}
appended_answers++;
return appended_answers;
}
/**
* @brief Append PTR answers to packet
*
@ -1238,6 +1308,8 @@ static uint8_t _mdns_append_answer(uint8_t *packet, uint16_t *index, mdns_out_an
if (answer->type == MDNS_TYPE_PTR) {
if (answer->service) {
return _mdns_append_service_ptr_answers(packet, index, answer->service, answer->flush, answer->bye);
} else if (answer->host && answer->host->hostname && strstr(answer->host->hostname, "in-addr")) {
return _mdns_append_reverse_ptr_record(packet, index, answer->host->hostname, answer->flush, answer->bye) > 0;
} else {
return _mdns_append_ptr_record(packet, index,
answer->custom_instance, answer->custom_service, answer->custom_proto,
@ -1639,6 +1711,15 @@ static bool _mdns_create_answer_from_service(mdns_tx_packet_t *packet, mdns_serv
return true;
}
static bool _mdns_create_answer_from_reverse_query(mdns_tx_packet_t * packet, const char * hostname, bool send_flush)
{
mdns_host_item_t * host = mdns_get_host_item(hostname);
if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_PTR, NULL, host, send_flush, false)) {
return false;
}
return true;
}
static bool _mdns_create_answer_from_hostname(mdns_tx_packet_t *packet, const char *hostname, bool send_flush)
{
mdns_host_item_t *host = mdns_get_host_item(hostname);
@ -1723,13 +1804,18 @@ static void _mdns_create_answer_from_parsed_packet(mdns_parsed_packet_t *parsed_
_mdns_free_tx_packet(packet);
return;
}
} else if (q->type == MDNS_TYPE_PTR) {
if (!_mdns_create_answer_from_reverse_query(packet, q->host, send_flush)) {
_mdns_free_tx_packet(packet);
return;
}
} else if (!_mdns_alloc_answer(&packet->answers, q->type, NULL, NULL, send_flush, false)) {
_mdns_free_tx_packet(packet);
return;
}
if (parsed_packet->src_port != MDNS_SERVICE_PORT && // Repeat the queries only for "One-Shot mDNS queries"
(q->type == MDNS_TYPE_ANY || q->type == MDNS_TYPE_A || q->type == MDNS_TYPE_AAAA)) {
(q->type == MDNS_TYPE_ANY || q->type == MDNS_TYPE_A || q->type == MDNS_TYPE_AAAA || q->type == MDNS_TYPE_PTR)) {
mdns_out_question_t *out_question = malloc(sizeof(mdns_out_question_t));
if (out_question == NULL) {
HOOK_MALLOC_FAILED;
@ -2948,7 +3034,7 @@ static bool _mdns_name_is_discovery(mdns_name_t *name, uint16_t type)
static bool _mdns_name_is_ours(mdns_name_t *name)
{
//domain have to be "local"
if (_str_null_or_empty(name->domain) || strcasecmp(name->domain, MDNS_DEFAULT_DOMAIN)) {
if (_str_null_or_empty(name->domain) || ( strcasecmp(name->domain, MDNS_DEFAULT_DOMAIN) && strcasecmp(name->domain, "arpa")) ) {
return false;
}