void DNS::add_record(const Resource &resource, const sections_type §ions) {
// We need to check that the data provided is correct. Otherwise, the sections
// will end up being inconsistent.
IPv4Address v4_addr;
IPv6Address v6_addr;
std::string buffer = encode_domain_name(resource.dname()), encoded_data;
// By default the data size is the length of the data field.
uint32_t data_size = resource.data().size();
if(resource.type() == A) {
v4_addr = resource.data();
data_size = 4;
}
else if(resource.type() == AAAA) {
v6_addr = resource.data();
data_size = IPv6Address::address_size;
}
else if(contains_dname(resource.type())) {
encoded_data = encode_domain_name(resource.data());
data_size = encoded_data.size();
}
uint32_t offset = buffer.size() + sizeof(uint16_t) * 3 + sizeof(uint32_t) + data_size,
threshold = sections.empty() ? records_data.size() : *sections.front().first;
// Skip the preference field
if(resource.type() == MX) {
offset += sizeof(uint16_t);
}
for(size_t i = 0; i < sections.size(); ++i) {
update_records(*sections[i].first, sections[i].second, threshold, offset);
}
records_data.insert(
records_data.begin() + threshold,
offset,
0
);
uint8_t *ptr = std::copy(
buffer.begin(),
buffer.end(),
&records_data[threshold]
);
uint16_t uint16_t_buffer;
uint32_t uint32_t_buffer;
uint16_t_buffer = Endian::host_to_be(resource.type());
std::memcpy(ptr, &uint16_t_buffer, sizeof(uint16_t));
ptr += sizeof(uint16_t);
uint16_t_buffer = Endian::host_to_be(resource.query_class());
std::memcpy(ptr, &uint16_t_buffer, sizeof(uint16_t));
ptr += sizeof(uint16_t);
uint32_t_buffer = Endian::host_to_be(resource.ttl());
std::memcpy(ptr, &uint32_t_buffer, sizeof(uint32_t));
ptr += sizeof(uint32_t);
uint16_t_buffer = Endian::host_to_be<uint16_t>(
data_size + (resource.type() == MX ? 2 : 0)
);
std::memcpy(ptr, &uint16_t_buffer, sizeof(uint16_t));
ptr += sizeof(uint16_t);
if(resource.type() == MX) {
ptr += sizeof(uint16_t);
}
if(resource.type() == A) {
uint32_t ip_int = v4_addr;
std::memcpy(ptr, &ip_int, sizeof(ip_int));
}
else if(resource.type() == AAAA) {
std::copy(v6_addr.begin(), v6_addr.end(), ptr);
}
else if(!encoded_data.empty()) {
std::copy(encoded_data.begin(), encoded_data.end(), ptr);
}
else {
std::copy(resource.data().begin(), resource.data().end(), ptr);
}
}
