jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2021, Sergey Bugaev <bugaevc@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include "DNSServer.h"
8#include "LookupServer.h"
9#include <AK/IPv4Address.h>
10#include <LibDNS/Packet.h>
11
12namespace LookupServer {
13
14using namespace DNS;
15
16DNSServer::DNSServer(Object* parent)
17 : Core::UDPServer(parent)
18{
19 bind(IPv4Address(), 53);
20 on_ready_to_receive = [this]() {
21 auto result = handle_client();
22 if (result.is_error()) {
23 dbgln("DNSServer: Failed to handle client: {}", result.error());
24 }
25 };
26}
27
28ErrorOr<void> DNSServer::handle_client()
29{
30 sockaddr_in client_address;
31 auto buffer = TRY(receive(1024, client_address));
32 auto optional_request = Packet::from_raw_packet(buffer.data(), buffer.size());
33 if (!optional_request.has_value()) {
34 dbgln("Got an invalid DNS packet");
35 return {};
36 }
37 auto& request = optional_request.value();
38
39 if (!request.is_query()) {
40 dbgln("It's not a request");
41 return {};
42 }
43
44 LookupServer& lookup_server = LookupServer::the();
45
46 Packet response;
47 response.set_is_response();
48 response.set_id(request.id());
49
50 for (auto& question : request.questions()) {
51 if (question.class_code() != RecordClass::IN)
52 continue;
53 response.add_question(question);
54 auto answers = TRY(lookup_server.lookup(question.name(), question.record_type()));
55 for (auto& answer : answers) {
56 response.add_answer(answer);
57 }
58 }
59
60 if (response.answer_count() == 0)
61 response.set_code(Packet::Code::NXDOMAIN);
62 else
63 response.set_code(Packet::Code::NOERROR);
64
65 buffer = TRY(response.to_byte_buffer());
66
67 TRY(send(buffer, client_address));
68 return {};
69}
70
71}