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mdns: fix bit order issue in DNS header flags

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The bit field in the header flags does not match its intended order on
little endian machines. The PR removes the bit field and uses bit
operations instead.
This commit is contained in:
Jiacheng Guo
2022-07-26 15:01:49 +08:00
committed by David Cermak
parent 85ba60e405
commit c4e85bd099
2 changed files with 15 additions and 27 deletions
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22
components/mdns/mdns.c
View File

@ -1686,7 +1686,7 @@ static void _mdns_create_answer_from_parsed_packet(mdns_parsed_packet_t *parsed_
if (!packet) { if (!packet) {
return; return;
} }
packet->flags = MDNS_FLAGS_AUTHORITATIVE; packet->flags = MDNS_FLAGS_QR_AUTHORITATIVE;
packet->distributed = parsed_packet->distributed; packet->distributed = parsed_packet->distributed;
packet->id = parsed_packet->id; packet->id = parsed_packet->id;
@ -1935,7 +1935,7 @@ static mdns_tx_packet_t * _mdns_create_announce_packet(mdns_if_t tcpip_if, mdns_
if (!packet) { if (!packet) {
return NULL; return NULL;
} }
packet->flags = MDNS_FLAGS_AUTHORITATIVE; packet->flags = MDNS_FLAGS_QR_AUTHORITATIVE;
uint8_t i; uint8_t i;
for (i=0; i<len; i++) { for (i=0; i<len; i++) {
@ -1965,7 +1965,7 @@ static mdns_tx_packet_t * _mdns_create_announce_from_probe(mdns_tx_packet_t * pr
if (!packet) { if (!packet) {
return NULL; return NULL;
} }
packet->flags = MDNS_FLAGS_AUTHORITATIVE; packet->flags = MDNS_FLAGS_QR_AUTHORITATIVE;
mdns_out_answer_t * s = probe->servers; mdns_out_answer_t * s = probe->servers;
while (s) { while (s) {
@ -2005,7 +2005,7 @@ static void _mdns_pcb_send_bye(mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protoco
if (!packet) { if (!packet) {
return; return;
} }
packet->flags = MDNS_FLAGS_AUTHORITATIVE; packet->flags = MDNS_FLAGS_QR_AUTHORITATIVE;
size_t i; size_t i;
for (i=0; i<len; i++) { for (i=0; i<len; i++) {
if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_PTR, services[i]->service, NULL, true, true)) { if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_PTR, services[i]->service, NULL, true, true)) {
@ -3342,13 +3342,13 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
memset(name, 0, sizeof(mdns_name_t)); memset(name, 0, sizeof(mdns_name_t));
header.id = _mdns_read_u16(data, MDNS_HEAD_ID_OFFSET); header.id = _mdns_read_u16(data, MDNS_HEAD_ID_OFFSET);
header.flags.value = _mdns_read_u16(data, MDNS_HEAD_FLAGS_OFFSET); header.flags = _mdns_read_u16(data, MDNS_HEAD_FLAGS_OFFSET);
header.questions = _mdns_read_u16(data, MDNS_HEAD_QUESTIONS_OFFSET); header.questions = _mdns_read_u16(data, MDNS_HEAD_QUESTIONS_OFFSET);
header.answers = _mdns_read_u16(data, MDNS_HEAD_ANSWERS_OFFSET); header.answers = _mdns_read_u16(data, MDNS_HEAD_ANSWERS_OFFSET);
header.servers = _mdns_read_u16(data, MDNS_HEAD_SERVERS_OFFSET); header.servers = _mdns_read_u16(data, MDNS_HEAD_SERVERS_OFFSET);
header.additional = _mdns_read_u16(data, MDNS_HEAD_ADDITIONAL_OFFSET); header.additional = _mdns_read_u16(data, MDNS_HEAD_ADDITIONAL_OFFSET);
if (header.flags.value == MDNS_FLAGS_AUTHORITATIVE && packet->src_port != MDNS_SERVICE_PORT) { if (header.flags == MDNS_FLAGS_QR_AUTHORITATIVE && packet->src_port != MDNS_SERVICE_PORT) {
free(parsed_packet); free(parsed_packet);
return; return;
} }
@ -3362,8 +3362,8 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
parsed_packet->tcpip_if = packet->tcpip_if; parsed_packet->tcpip_if = packet->tcpip_if;
parsed_packet->ip_protocol = packet->ip_protocol; parsed_packet->ip_protocol = packet->ip_protocol;
parsed_packet->multicast = packet->multicast; parsed_packet->multicast = packet->multicast;
parsed_packet->authoritative = header.flags.value == MDNS_FLAGS_AUTHORITATIVE; parsed_packet->authoritative = (header.flags == MDNS_FLAGS_QR_AUTHORITATIVE);
parsed_packet->distributed = header.flags.value == MDNS_FLAGS_DISTRIBUTED; parsed_packet->distributed = header.flags == MDNS_FLAGS_DISTRIBUTED;
parsed_packet->id = header.id; parsed_packet->id = header.id;
esp_netif_ip_addr_copy(&parsed_packet->src, &packet->src); esp_netif_ip_addr_copy(&parsed_packet->src, &packet->src);
parsed_packet->src_port = packet->src_port; parsed_packet->src_port = packet->src_port;
@ -3499,7 +3499,7 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
service = _mdns_get_service_item(name->service, name->proto, NULL); service = _mdns_get_service_item(name->service, name->proto, NULL);
} }
} else { } else {
if (!header.flags.qr || record_type == MDNS_NS) { if ((header.flags & MDNS_FLAGS_QUERY_REPSONSE) == 0 || record_type == MDNS_NS) {
//skip this record //skip this record
continue; continue;
} }
@ -6075,11 +6075,11 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
header.additional = _mdns_read_u16(data, MDNS_HEAD_ADDITIONAL_OFFSET); header.additional = _mdns_read_u16(data, MDNS_HEAD_ADDITIONAL_OFFSET);
_mdns_dbg_printf("%s", _mdns_dbg_printf("%s",
(header.flags.value == MDNS_FLAGS_AUTHORITATIVE)?"AUTHORITATIVE\n": (header.flags.value == MDNS_FLAGS_QR_AUTHORITATIVE)?"AUTHORITATIVE\n":
(header.flags.value == MDNS_FLAGS_DISTRIBUTED)?"DISTRIBUTED\n": (header.flags.value == MDNS_FLAGS_DISTRIBUTED)?"DISTRIBUTED\n":
(header.flags.value == 0)?"\n":" " (header.flags.value == 0)?"\n":" "
); );
if (header.flags.value && header.flags.value != MDNS_FLAGS_AUTHORITATIVE) { if (header.flags.value && header.flags.value != MDNS_FLAGS_QR_AUTHORITATIVE) {
_mdns_dbg_printf("0x%04X\n", header.flags.value); _mdns_dbg_printf("0x%04X\n", header.flags.value);
} }

20
components/mdns/private_include/mdns_private.h
View File

@ -71,7 +71,9 @@
#define MDNS_ANSWER_A_TTL 120 #define MDNS_ANSWER_A_TTL 120
#define MDNS_ANSWER_AAAA_TTL 120 #define MDNS_ANSWER_AAAA_TTL 120
#define MDNS_FLAGS_AUTHORITATIVE 0x8400 #define MDNS_FLAGS_QUERY_REPSONSE 0x8000
#define MDNS_FLAGS_AUTHORITATIVE 0x0400
#define MDNS_FLAGS_QR_AUTHORITATIVE (MDNS_FLAGS_QUERY_REPSONSE | MDNS_FLAGS_AUTHORITATIVE)
#define MDNS_FLAGS_DISTRIBUTED 0x0200 #define MDNS_FLAGS_DISTRIBUTED 0x0200
#define MDNS_NAME_REF 0xC000 #define MDNS_NAME_REF 0xC000
@ -211,21 +213,7 @@ typedef enum {
typedef struct { typedef struct {
uint16_t id; uint16_t id;
union { uint16_t flags;
struct {
uint16_t qr :1;
uint16_t opCode :4;
uint16_t aa :1;
uint16_t tc :1;
uint16_t rd :1;
uint16_t ra :1;
uint16_t z :1;
uint16_t ad :1;
uint16_t cd :1;
uint16_t rCode :4;//response/error code
};
uint16_t value;
} flags;
uint16_t questions; //QDCOUNT uint16_t questions; //QDCOUNT
uint16_t answers; //ANCOUNT uint16_t answers; //ANCOUNT
uint16_t servers; //NSCOUNT uint16_t servers; //NSCOUNT