diff --git a/components/mdns/mdns.c b/components/mdns/mdns.c index fc9b5394d..766877fb3 100644 --- a/components/mdns/mdns.c +++ b/components/mdns/mdns.c @@ -513,6 +513,37 @@ static inline uint8_t _mdns_append_string(uint8_t * packet, uint16_t * index, co return len + 1; } +/** + * @brief appends one TXT record ("key=value" or "key") + * + * @param packet MDNS packet + * @param index offset in the packet + * @param txt one txt record + * + * @return length of added data: length of the added txt value + 1 on success + * 0 if data won't fit the packet + * -1 if invalid TXT entry + */ +static inline int append_one_txt_record_entry(uint8_t * packet, uint16_t * index, mdns_txt_linked_item_t * txt) +{ + if (txt == NULL || txt->key == NULL) { + return -1; + } + size_t key_len = strlen(txt->key); + size_t len = key_len + txt->value_len + (txt->value ? 1 : 0); + if ((*index + len + 1) >= MDNS_MAX_PACKET_SIZE) { + return 0; + } + _mdns_append_u8(packet, index, len); + memcpy(packet + *index, txt->key, key_len); + if (txt->value) { + packet[*index + key_len] = '='; + memcpy(packet + *index + key_len + 1, txt->value, txt->value_len); + } + *index += len; + return len + 1; +} + /** * @brief appends FQDN to a packet, incrementing the index and * compressing the output if previous occurrence of the string (or part of it) has been found @@ -775,19 +806,13 @@ static uint16_t _mdns_append_txt_record(uint8_t * packet, uint16_t * index, mdns uint16_t data_len_location = *index - 2; uint16_t data_len = 0; - char * tmp; mdns_txt_linked_item_t * txt = service->txt; while (txt) { - if (asprintf(&tmp, "%s%s%.*s", txt->key, txt->value ? "=" : "", txt->value_len, txt->value) > 0) { - uint8_t l = _mdns_append_string(packet, index, tmp); - free(tmp); - if (!l) { - return 0; - } + int l = append_one_txt_record_entry(packet, index, txt); + if (l > 0) { data_len += l; - } else { - HOOK_MALLOC_FAILED; - // continue + } else if (l == 0) { // TXT entry won't fit into the mdns packet + return 0; } txt = txt->next; } @@ -2574,17 +2599,10 @@ static int _mdns_check_txt_collision(mdns_service_t * service, const uint8_t * d uint8_t ours[len]; uint16_t index = 0; - char * tmp; txt = service->txt; while (txt) { - if (asprintf(&tmp, "%s%s%.*s", txt->key, txt->value ? "=" : "", txt->value_len, txt->value) > 0) { - _mdns_append_string(ours, &index, tmp); - free(tmp); - } else { - HOOK_MALLOC_FAILED; - // continue - } + append_one_txt_record_entry(ours, &index, txt); txt = txt->next; }