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https://github.com/espressif/esp-idf.git
synced 2024-10-05 20:47:46 -04:00
mdns: Fix potential read behind parsed packet
This commit is contained in:
David Cermak
parent
d6ad597b0f
commit
0bd2c55413
@ -299,10 +299,11 @@ static mdns_srv_item_t *_mdns_get_service_item_instance(const char *instance, co
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*
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* @return the address after the parsed FQDN in the packet or NULL on error
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*/
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static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, char * buf)
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static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, char * buf, size_t packet_len)
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{
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size_t index = 0;
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while (start[index]) {
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const uint8_t * packet_end = packet + packet_len;
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while (start + index < packet_end && start[index]) {
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if (name->parts == 4) {
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name->invalid = true;
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}
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@ -314,6 +315,9 @@ static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * s
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}
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uint8_t i;
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for (i=0; i<len; i++) {
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if (start + index >= packet_end) {
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return NULL;
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}
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buf[i] = start[index++];
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}
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buf[len] = '\0';
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@ -336,7 +340,7 @@ static const uint8_t * _mdns_read_fqdn(const uint8_t * packet, const uint8_t * s
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//reference address can not be after where we are
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return NULL;
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}
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if (_mdns_read_fqdn(packet, packet + address, name, buf)) {
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if (_mdns_read_fqdn(packet, packet + address, name, buf, packet_len)) {
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return start + index;
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}
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return NULL;
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@ -536,7 +540,7 @@ static inline int append_one_txt_record_entry(uint8_t * packet, uint16_t * index
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*
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* @return length of added data: 0 on error or length on success
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*/
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static uint16_t _mdns_append_fqdn(uint8_t * packet, uint16_t * index, const char * strings[], uint8_t count)
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static uint16_t _mdns_append_fqdn(uint8_t * packet, uint16_t * index, const char * strings[], uint8_t count, size_t packet_len)
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{
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if (!count) {
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//empty string so terminate
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@ -563,7 +567,7 @@ search_next:
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name.service[0] = 0;
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name.proto[0] = 0;
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name.domain[0] = 0;
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const uint8_t * content = _mdns_read_fqdn(packet, len_location, &name, buf);
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const uint8_t * content = _mdns_read_fqdn(packet, len_location, &name, buf, packet_len);
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if (!content) {
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//not a readable fqdn?
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return 0;
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@ -589,7 +593,7 @@ search_next:
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return 0;
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}
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//run the same for the other strings in the name
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return written + _mdns_append_fqdn(packet, index, &strings[1], count - 1);
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return written + _mdns_append_fqdn(packet, index, &strings[1], count - 1, packet_len);
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}
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//we have found the string so let's insert a pointer to it instead
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@ -623,7 +627,7 @@ static uint16_t _mdns_append_ptr_record(uint8_t * packet, uint16_t * index, cons
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str[2] = proto;
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str[3] = MDNS_DEFAULT_DOMAIN;
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part_length = _mdns_append_fqdn(packet, index, str + 1, 3);
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part_length = _mdns_append_fqdn(packet, index, str + 1, 3, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -636,7 +640,7 @@ static uint16_t _mdns_append_ptr_record(uint8_t * packet, uint16_t * index, cons
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record_length += part_length;
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uint16_t data_len_location = *index - 2;
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part_length = _mdns_append_fqdn(packet, index, str, 4);
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part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -675,7 +679,7 @@ static uint16_t _mdns_append_sdptr_record(uint8_t * packet, uint16_t * index, md
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str[1] = service->proto;
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str[2] = MDNS_DEFAULT_DOMAIN;
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part_length = _mdns_append_fqdn(packet, index, sd_str, 4);
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part_length = _mdns_append_fqdn(packet, index, sd_str, 4, MDNS_MAX_PACKET_SIZE);
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record_length += part_length;
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@ -686,7 +690,7 @@ static uint16_t _mdns_append_sdptr_record(uint8_t * packet, uint16_t * index, md
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record_length += part_length;
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uint16_t data_len_location = *index - 2;
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part_length = _mdns_append_fqdn(packet, index, str, 3);
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part_length = _mdns_append_fqdn(packet, index, str, 3, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -724,7 +728,7 @@ static uint16_t _mdns_append_txt_record(uint8_t * packet, uint16_t * index, mdns
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return 0;
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}
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part_length = _mdns_append_fqdn(packet, index, str, 4);
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part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -788,7 +792,7 @@ static uint16_t _mdns_append_srv_record(uint8_t * packet, uint16_t * index, mdns
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return 0;
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}
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part_length = _mdns_append_fqdn(packet, index, str, 4);
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part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -821,7 +825,7 @@ static uint16_t _mdns_append_srv_record(uint8_t * packet, uint16_t * index, mdns
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return 0;
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}
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part_length = _mdns_append_fqdn(packet, index, str, 2);
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part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -854,7 +858,7 @@ static uint16_t _mdns_append_a_record(uint8_t * packet, uint16_t * index, const
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return 0;
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}
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part_length = _mdns_append_fqdn(packet, index, str, 2);
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part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -906,7 +910,7 @@ static uint16_t _mdns_append_aaaa_record(uint8_t * packet, uint16_t * index, con
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}
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part_length = _mdns_append_fqdn(packet, index, str, 2);
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part_length = _mdns_append_fqdn(packet, index, str, 2, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -954,7 +958,7 @@ static uint16_t _mdns_append_question(uint8_t * packet, uint16_t * index, mdns_o
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str[str_index++] = q->domain;
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}
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part_length = _mdns_append_fqdn(packet, index, str, str_index);
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part_length = _mdns_append_fqdn(packet, index, str, str_index, MDNS_MAX_PACKET_SIZE);
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if (!part_length) {
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return 0;
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}
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@ -2804,7 +2808,7 @@ static inline uint32_t _mdns_read_u32(const uint8_t * packet, uint16_t index)
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*
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* @return the address after the parsed FQDN in the packet or NULL on error
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*/
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static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name)
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static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t * start, mdns_name_t * name, size_t packet_len)
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{
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name->parts = 0;
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name->sub = 0;
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@ -2816,7 +2820,7 @@ static const uint8_t * _mdns_parse_fqdn(const uint8_t * packet, const uint8_t *
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static char buf[MDNS_NAME_BUF_LEN];
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const uint8_t * next_data = (uint8_t*)_mdns_read_fqdn(packet, start, name, buf);
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const uint8_t * next_data = (uint8_t*)_mdns_read_fqdn(packet, start, name, buf, packet_len);
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if (!next_data) {
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return 0;
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}
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@ -3089,6 +3093,10 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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mdns_name_t * name = &n;
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memset(name, 0, sizeof(mdns_name_t));
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if (len <= MDNS_HEAD_ADDITIONAL_OFFSET) {
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free(parsed_packet);
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return;
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}
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header.id = _mdns_read_u16(data, MDNS_HEAD_ID_OFFSET);
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header.flags.value = _mdns_read_u16(data, MDNS_HEAD_FLAGS_OFFSET);
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header.questions = _mdns_read_u16(data, MDNS_HEAD_QUESTIONS_OFFSET);
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@ -3120,7 +3128,7 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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uint8_t qs = header.questions;
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while (qs--) {
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content = _mdns_parse_fqdn(data, content, name);
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content = _mdns_parse_fqdn(data, content, name, len);
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if (!content) {
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header.answers = 0;
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header.additional = 0;
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@ -3128,6 +3136,9 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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goto clear_rx_packet;//error
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}
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if (content + MDNS_CLASS_OFFSET + 1 >= data + len) {
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goto clear_rx_packet; // malformed packet, won't read behind it
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}
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uint16_t type = _mdns_read_u16(content, MDNS_TYPE_OFFSET);
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uint16_t mdns_class = _mdns_read_u16(content, MDNS_CLASS_OFFSET);
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bool unicast = !!(mdns_class & 0x8000);
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@ -3197,11 +3208,14 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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while (content < (data + len)) {
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content = _mdns_parse_fqdn(data, content, name);
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content = _mdns_parse_fqdn(data, content, name, len);
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if (!content) {
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goto clear_rx_packet;//error
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}
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if (content + MDNS_LEN_OFFSET + 1 >= data + len) {
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goto clear_rx_packet; // malformed packet, won't read behind it
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}
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uint16_t type = _mdns_read_u16(content, MDNS_TYPE_OFFSET);
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uint16_t mdns_class = _mdns_read_u16(content, MDNS_CLASS_OFFSET);
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uint32_t ttl = _mdns_read_u32(content, MDNS_TTL_OFFSET);
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@ -3247,7 +3261,7 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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}
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if (type == MDNS_TYPE_PTR) {
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if (!_mdns_parse_fqdn(data, data_ptr, name)) {
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if (!_mdns_parse_fqdn(data, data_ptr, name, len)) {
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continue;//error
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}
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if (search_result) {
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@ -3286,9 +3300,12 @@ void mdns_parse_packet(mdns_rx_packet_t * packet)
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}
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}
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if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name)) {
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if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name, len)) {
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continue;//error
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}
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if (data_ptr + MDNS_SRV_PORT_OFFSET + 1 >= data + len) {
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goto clear_rx_packet; // malformed packet, won't read behind it
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}
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uint16_t priority = _mdns_read_u16(data_ptr, MDNS_SRV_PRIORITY_OFFSET);
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uint16_t weight = _mdns_read_u16(data_ptr, MDNS_SRV_WEIGHT_OFFSET);
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uint16_t port = _mdns_read_u16(data_ptr, MDNS_SRV_PORT_OFFSET);
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@ -5644,8 +5661,8 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
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uint8_t qs = header.questions;
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while (qs--) {
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content = _mdns_parse_fqdn(data, content, name);
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if (!content) {
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content = _mdns_parse_fqdn(data, content, name, len);
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if (!content || content + MDNS_CLASS_OFFSET + 1 >= data + len) {
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header.answers = 0;
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header.additional = 0;
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header.servers = 0;
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@ -5695,7 +5712,7 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
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while (content < (data + len)) {
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content = _mdns_parse_fqdn(data, content, name);
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content = _mdns_parse_fqdn(data, content, name, len);
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if (!content) {
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_mdns_dbg_printf("ERROR: parse mdns records\n");
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break;
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@ -5763,13 +5780,13 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
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_mdns_dbg_printf("%u ", ttl);
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_mdns_dbg_printf("[%u] ", data_len);
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if (type == MDNS_TYPE_PTR) {
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if (!_mdns_parse_fqdn(data, data_ptr, name)) {
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if (!_mdns_parse_fqdn(data, data_ptr, name, len)) {
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_mdns_dbg_printf("ERROR: parse PTR\n");
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continue;
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}
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_mdns_dbg_printf("%s.%s.%s.%s.\n", name->host, name->service, name->proto, name->domain);
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} else if (type == MDNS_TYPE_SRV) {
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if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name)) {
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if (!_mdns_parse_fqdn(data, data_ptr + MDNS_SRV_FQDN_OFFSET, name, len)) {
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_mdns_dbg_printf("ERROR: parse SRV\n");
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continue;
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}
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@ -5807,7 +5824,7 @@ void mdns_debug_packet(const uint8_t * data, size_t len)
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_mdns_dbg_printf(IPSTR "\n", IP2STR(&ip));
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} else if (type == MDNS_TYPE_NSEC) {
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const uint8_t * old_ptr = data_ptr;
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const uint8_t * new_ptr = _mdns_parse_fqdn(data, data_ptr, name);
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const uint8_t * new_ptr = _mdns_parse_fqdn(data, data_ptr, name, len);
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if (new_ptr) {
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_mdns_dbg_printf("%s.%s.%s.%s. ", name->host, name->service, name->proto, name->domain);
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size_t diff = new_ptr - old_ptr;
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@ -91,6 +91,7 @@ def mdns_server(esp_host):
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console_log('Received query: {} '.format(dns.__repr__()))
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sock.sendto(get_dns_answer_to_mdns_lwip(TESTER_NAME_LWIP, dns.id), addr)
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if len(dns.an) > 0 and dns.an[0].type == dpkt.dns.DNS_A:
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console_log('Received answer from {}'.format(dns.an[0].name))
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if dns.an[0].name == esp_host + u'.local':
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console_log('Received answer to esp32-mdns query: {}'.format(dns.__repr__()))
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esp_answered.set()
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