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mdns: support for multi-packet known answer (questions with TC bit)
This allow Apple Bonjour Conformance Test to not fail with the following tests: - DISTRIBUTED DUPLICATE SUPPRESSION - MULTIPLE QUESTIONS - DISTRIBUTED DUPLICATE SUPPRESSION Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
This commit is contained in:
David Girault
Simon Goldschmidt
parent
e85e473838
commit
9301225895
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@ -18,7 +18,6 @@
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* - Sending goodbye messages (zero ttl) - shutdown, DHCP lease about to expire, DHCP turned off...
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* - Sending negative responses NSEC
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* - Fragmenting replies if required
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* - Handling multi-packet known answers (TC bit)
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* - Individual known answer detection for all local IPv6 addresses
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* - Dynamic size of outgoing packet
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*/
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@ -64,6 +63,7 @@
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#include "lwip/udp.h"
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#include "lwip/ip_addr.h"
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#include "lwip/mem.h"
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#include "lwip/memp.h"
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#include "lwip/prot/dns.h"
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#include "lwip/prot/iana.h"
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#include "lwip/timeouts.h"
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@ -119,6 +119,11 @@ static mdns_name_result_cb_t mdns_name_result_cb;
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#define MDNS_RESPONSE_DELAY_MIN 20
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#define MDNS_RESPONSE_DELAY (LWIP_RAND() %(MDNS_RESPONSE_DELAY_MAX - \
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MDNS_RESPONSE_DELAY_MIN) + MDNS_RESPONSE_DELAY_MIN)
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/* Delayed response for truncated question defines */
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#define MDNS_RESPONSE_TC_DELAY_MAX 500
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#define MDNS_RESPONSE_TC_DELAY_MIN 400
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#define MDNS_RESPONSE_TC_DELAY_MS (LWIP_RAND() % (MDNS_RESPONSE_TC_DELAY_MAX - \
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MDNS_RESPONSE_TC_DELAY_MIN) + MDNS_RESPONSE_TC_DELAY_MIN)
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/** Probing & announcing defines */
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#define MDNS_PROBE_DELAY_MS 250
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@ -174,8 +179,18 @@ struct mdns_packet {
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u16_t additional;
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/** Number of unparsed additional answers */
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u16_t additional_left;
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/** Chained list of known answer received after a truncated question */
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struct mdns_packet *next_answer;
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/** Chained list of truncated question that are waiting */
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struct mdns_packet *next_tc_question;
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};
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/* list of received questions with TC flags set, waiting for known answers */
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static struct mdns_packet *pending_tc_questions;
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/* pool of received packets */
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LWIP_MEMPOOL_DECLARE(MDNS_PKTS, MDNS_MAX_STORED_PKTS, sizeof (struct mdns_packet), "Stored mDNS packets")
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struct mdns_question {
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struct mdns_rr_info info;
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/** unicast reply requested */
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@ -1364,7 +1379,7 @@ mdns_add_msg_to_delayed(struct mdns_outmsg *dest, struct mdns_outmsg *src)
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* - Define which type of answer is requested
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* - Send out packet or put it on hold until after random time
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*
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* @param pkt incoming packet
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* @param pkt incoming packet (in stack)
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* @param netif network interface of incoming packet
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*/
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static void
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@ -1410,6 +1425,17 @@ mdns_handle_question(struct mdns_packet *pkt, struct netif *netif)
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if (res != ERR_OK) {
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return;
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}
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if (pkt->next_answer) {
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/* Also parse known-answers from additional packets */
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struct mdns_packet *pkta = pkt->next_answer;
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while (pkta) {
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res = mdns_parse_pkt_known_answers(netif, pkta, &reply);
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if (res != ERR_OK) {
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return;
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}
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pkta = pkta->next_answer;
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}
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}
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/* Parse authoritative answers -> probing */
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/* If it's a probe query, we need to directly answer via unicast. */
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res = mdns_parse_pkt_authoritative_answers(netif, pkt, &reply);
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@ -1664,6 +1690,44 @@ mdns_handle_question(struct mdns_packet *pkt, struct netif *netif)
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}
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}
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/**
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* Handle truncated question MDNS packet
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* - Called by timer
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* - Call mdns_handle_question
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* - Do cleanup
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*
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* @param pkt incoming packet (in pool)
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*/
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static void
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mdns_handle_tc_question(void *arg)
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{
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struct mdns_packet *pkt = (struct mdns_packet *)arg;
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struct netif *from = netif_get_by_index(pkt->pbuf->if_idx);
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/* timer as elapsed, now handle this question */
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mdns_handle_question(pkt, from);
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/* remove from pending list */
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if (pending_tc_questions == pkt) {
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pending_tc_questions = pkt->next_tc_question;
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}
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else {
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struct mdns_packet *prev = pending_tc_questions;
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while (prev && prev->next_tc_question != pkt) {
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prev = prev->next_tc_question;
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}
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LWIP_ASSERT("pkt not found in pending_tc_questions list", prev != NULL);
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prev->next_tc_question = pkt->next_tc_question;
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}
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/* free linked answers and this question */
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while (pkt->next_answer) {
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struct mdns_packet *ans = pkt->next_answer;
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pkt->next_answer = ans->next_answer;
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pbuf_free(ans->pbuf);
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LWIP_MEMPOOL_FREE(MDNS_PKTS, ans);
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}
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pbuf_free(pkt->pbuf);
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LWIP_MEMPOOL_FREE(MDNS_PKTS, pkt);
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}
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/**
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* Handle a probe conflict:
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* - Check if we exceeded the maximum of 15 conflicts in 10seconds.
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@ -2067,6 +2131,43 @@ mdns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr,
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if (hdr.flags1 & DNS_FLAG1_RESPONSE) {
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mdns_handle_response(&packet, recv_netif);
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} else {
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if (packet.questions && hdr.flags1 & DNS_FLAG1_TRUNC) {
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/* this is a new truncated question */
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struct mdns_packet *pkt = (struct mdns_packet *)LWIP_MEMPOOL_ALLOC(MDNS_PKTS);
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if (!pkt)
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goto dealloc; /* don't reply truncated question if alloc error */
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SMEMCPY(pkt, &packet, sizeof(packet));
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/* insert this question in pending list */
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pkt->next_tc_question = pending_tc_questions;
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pending_tc_questions = pkt;
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/* question with truncated flags, need to wait 400-500ms before replying */
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sys_timeout(MDNS_RESPONSE_TC_DELAY_MS, mdns_handle_tc_question, pkt);
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/* return without dealloc pbuf */
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return;
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}
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else if (!packet.questions && packet.answers && pending_tc_questions) {
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/* this packet is a known-answer packet for a truncated question previously received */
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struct mdns_packet *q = pending_tc_questions;
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while (q) {
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if ((packet.source_port == q->source_port) &&
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ip_addr_cmp(&packet.source_addr, &q->source_addr))
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break;
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q = q->next_tc_question;
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}
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if (q) {
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/* found question from the same source */
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struct mdns_packet *pkt = (struct mdns_packet *)LWIP_MEMPOOL_ALLOC(MDNS_PKTS);
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if (!pkt)
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goto dealloc; /* don't reply truncated question if alloc error */
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SMEMCPY(pkt, &packet, sizeof(packet));
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/* insert this known-ansert in question */
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pkt->next_answer = q->next_answer;
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q->next_answer = pkt;
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/* nothing more to do */
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return;
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}
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}
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/* if previous tests fail, handle this question normally */
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mdns_handle_question(&packet, recv_netif);
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}
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@ -2675,10 +2776,10 @@ mdns_resp_init(void)
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err_t res;
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/* LWIP_ASSERT_CORE_LOCKED(); is checked by udp_new() */
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#if LWIP_MDNS_SEARCH
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memset(mdns_requests, 0, sizeof(mdns_requests));
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#endif
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LWIP_MEMPOOL_INIT(MDNS_PKTS);
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mdns_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
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LWIP_ASSERT("Failed to allocate pcb", mdns_pcb != NULL);
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#if LWIP_MULTICAST_TX_OPTIONS
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@ -60,6 +60,16 @@
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#define MDNS_MAX_SERVICES 1
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#endif
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/** The maximum number of received packets stored in chained list of known
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* answers for pending truncated questions. This value define the size of
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* the MDNS_PKTS mempool.
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* Up to MDNS_MAX_STORED_PKTS pbuf can be stored in addition to TC questions
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* that are pending.
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*/
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#ifndef MDNS_MAX_STORED_PKTS
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#define MDNS_MAX_STORED_PKTS 4
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#endif
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/** Payload size allocated for each outgoing UDP packet. Will be allocated with
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* PBUF_RAM and freed after packet was sent.
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* According to RFC 6762, there is no reason to retain the 512 bytes restriction
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