mirror of
https://github.com/RGBCube/serenity
synced 2025-05-28 15:45:09 +00:00
94ca55cefd
As suggested by Joshua, this commit adds the 2-clause BSD license as a comment block to the top of every source file. For the first pass, I've just added myself for simplicity. I encourage everyone to add themselves as copyright holders of any file they've added or modified in some significant way. If I've added myself in error somewhere, feel free to replace it with the appropriate copyright holder instead. Going forward, all new source files should include a license header.
339 lines
11 KiB
C++
339 lines
11 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "LookupServer.h"
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#include "DNSPacket.h"
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#include "DNSRecord.h"
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#include <AK/BufferStream.h>
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#include <AK/ByteBuffer.h>
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#include <AK/HashMap.h>
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#include <AK/String.h>
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#include <AK/StringBuilder.h>
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#include <Kernel/Net/IPv4.h>
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#include <LibCore/CConfigFile.h>
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#include <LibCore/CEventLoop.h>
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#include <LibCore/CFile.h>
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#include <LibCore/CLocalServer.h>
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#include <LibCore/CLocalSocket.h>
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#include <LibCore/CSyscallUtils.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/select.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <time.h>
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#include <unistd.h>
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#define T_A 1
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#define T_NS 2
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#define T_CNAME 5
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#define T_SOA 6
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#define T_PTR 12
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#define T_MX 15
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#define C_IN 1
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LookupServer::LookupServer()
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{
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auto config = CConfigFile::get_for_system("LookupServer");
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dbg() << "Using network config file at " << config->file_name();
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m_dns_ip = config->read_entry("DNS", "IPAddress", "127.0.0.53");
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load_etc_hosts();
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m_local_server = CLocalServer::construct(this);
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m_local_server->on_ready_to_accept = [this]() {
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auto socket = m_local_server->accept();
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socket->on_ready_to_read = [this, socket]() {
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service_client(socket);
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RefPtr<CLocalSocket> keeper = socket;
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const_cast<CLocalSocket&>(*socket).on_ready_to_read = []{};
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};
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};
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bool ok = m_local_server->take_over_from_system_server();
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ASSERT(ok);
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}
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void LookupServer::load_etc_hosts()
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{
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dbg() << "Loading hosts from /etc/hosts";
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auto file = CFile::construct("/etc/hosts");
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if (!file->open(CIODevice::ReadOnly))
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return;
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while (!file->eof()) {
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auto line = file->read_line(1024);
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if (line.is_empty())
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break;
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auto str_line = String((const char*)line.data(), line.size() - 1, Chomp);
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auto fields = str_line.split('\t');
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auto sections = fields[0].split('.');
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IPv4Address addr {
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(u8)atoi(sections[0].characters()),
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(u8)atoi(sections[1].characters()),
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(u8)atoi(sections[2].characters()),
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(u8)atoi(sections[3].characters()),
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};
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auto name = fields[1];
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m_dns_custom_hostnames.set(name, addr.to_string());
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IPv4Address reverse_addr {
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(u8)atoi(sections[3].characters()),
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(u8)atoi(sections[2].characters()),
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(u8)atoi(sections[1].characters()),
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(u8)atoi(sections[0].characters()),
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};
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StringBuilder builder;
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builder.append(reverse_addr.to_string());
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builder.append(".in-addr.arpa");
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m_dns_custom_hostnames.set(builder.to_string(), name);
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}
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}
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void LookupServer::service_client(RefPtr<CLocalSocket> socket)
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{
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u8 client_buffer[1024];
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int nrecv = socket->read(client_buffer, sizeof(client_buffer) - 1);
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if (nrecv < 0) {
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perror("read");
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return;
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}
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client_buffer[nrecv] = '\0';
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char lookup_type = client_buffer[0];
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if (lookup_type != 'L' && lookup_type != 'R') {
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dbg() << "Invalid lookup_type " << lookup_type;
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return;
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}
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auto hostname = String((const char*)client_buffer + 1, nrecv - 1, Chomp);
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dbg() << "Got request for '" << hostname << "' (using IP " << m_dns_ip << ")";
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Vector<String> responses;
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if (auto known_host = m_dns_custom_hostnames.get(hostname)) {
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responses.append(known_host.value());
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} else if (!hostname.is_empty()) {
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bool did_timeout;
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int retries = 3;
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do {
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did_timeout = false;
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if (lookup_type == 'L')
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responses = lookup(hostname, did_timeout, T_A);
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else if (lookup_type == 'R')
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responses = lookup(hostname, did_timeout, T_PTR);
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if (!did_timeout)
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break;
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} while (--retries);
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if (did_timeout) {
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fprintf(stderr, "LookupServer: Out of retries :(\n");
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return;
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}
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}
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if (responses.is_empty()) {
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int nsent = socket->write("Not found.\n");
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if (nsent < 0)
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perror("write");
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return;
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}
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for (auto& response : responses) {
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auto line = String::format("%s\n", response.characters());
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int nsent = socket->write(line);
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if (nsent < 0) {
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perror("write");
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break;
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}
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}
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}
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String LookupServer::parse_dns_name(const u8* data, int& offset, int max_offset)
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{
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Vector<char, 128> buf;
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while (offset < max_offset) {
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u8 ch = data[offset];
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if (ch == '\0') {
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++offset;
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break;
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}
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if ((ch & 0xc0) == 0xc0) {
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ASSERT_NOT_REACHED();
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// FIXME: Parse referential names.
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offset += 2;
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}
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for (int i = 0; i < ch; ++i) {
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buf.append(data[offset + i + 1]);
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}
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buf.append('.');
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offset += ch + 1;
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}
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return String::copy(buf);
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}
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Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, unsigned short record_type)
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{
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if (auto it = m_lookup_cache.find(hostname); it != m_lookup_cache.end()) {
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auto& cached_lookup = it->value;
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if (cached_lookup.record_type == record_type && cached_lookup.timestamp < (time(nullptr) + 60)) {
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return it->value.responses;
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}
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m_lookup_cache.remove(it);
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}
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DNSPacket request_header;
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request_header.set_id(get_next_id());
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request_header.set_is_query();
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request_header.set_opcode(0);
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request_header.set_truncated(false);
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request_header.set_recursion_desired(true);
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request_header.set_question_count(1);
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auto buffer = ByteBuffer::create_uninitialized(1024);
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{
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BufferStream stream(buffer);
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stream << ByteBuffer::wrap(&request_header, sizeof(request_header));
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auto parts = hostname.split('.');
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for (auto& part : parts) {
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stream << (u8)part.length();
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stream << part;
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}
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stream << '\0';
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stream << htons(record_type);
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stream << htons(C_IN);
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stream.snip();
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}
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int fd = socket(AF_INET, SOCK_DGRAM, 0);
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if (fd < 0) {
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perror("socket");
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return {};
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}
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struct timeval timeout {
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1, 0
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};
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int rc = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
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if (rc < 0) {
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perror("setsockopt");
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close(fd);
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return {};
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}
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struct sockaddr_in dst_addr;
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memset(&dst_addr, 0, sizeof(dst_addr));
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dst_addr.sin_family = AF_INET;
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dst_addr.sin_port = htons(53);
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rc = inet_pton(AF_INET, m_dns_ip.characters(), &dst_addr.sin_addr);
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int nsent = sendto(fd, buffer.data(), buffer.size(), 0, (const struct sockaddr*)&dst_addr, sizeof(dst_addr));
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if (nsent < 0) {
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perror("sendto");
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return {};
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}
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ASSERT(nsent == buffer.size());
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struct sockaddr_in src_addr;
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socklen_t src_addr_len = sizeof(src_addr);
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u8 response_buffer[4096];
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ssize_t nrecv = recvfrom(fd, response_buffer, sizeof(response_buffer) - 1, 0, (struct sockaddr*)&src_addr, &src_addr_len);
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if (nrecv < 0) {
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if (errno == EAGAIN) {
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did_timeout = true;
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} else {
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perror("recvfrom");
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}
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close(fd);
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return {};
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}
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close(fd);
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response_buffer[nrecv] = '\0';
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if (nrecv < (int)sizeof(DNSPacket)) {
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dbgprintf("LookupServer: Response not big enough (%d) to be a DNS packet :(\n", nrecv);
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return {};
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}
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auto& response_header = *(DNSPacket*)(response_buffer);
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dbgprintf("Got response (ID: %u)\n", response_header.id());
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dbgprintf(" Question count: %u\n", response_header.question_count());
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dbgprintf(" Answer count: %u\n", response_header.answer_count());
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dbgprintf(" Authority count: %u\n", response_header.authority_count());
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dbgprintf("Additional count: %u\n", response_header.additional_count());
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if (response_header.id() != request_header.id()) {
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dbgprintf("LookupServer: ID mismatch (%u vs %u) :(\n", response_header.id(), request_header.id());
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return {};
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}
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if (response_header.question_count() != 1) {
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dbgprintf("LookupServer: Question count (%u vs %u) :(\n", response_header.question_count(), request_header.question_count());
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return {};
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}
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if (response_header.answer_count() < 1) {
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dbgprintf("LookupServer: Not enough answers (%u) :(\n", response_header.answer_count());
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return {};
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}
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int offset = 0;
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auto question = parse_dns_name((const u8*)response_header.payload(), offset, nrecv);
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offset += 4;
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Vector<String> addresses;
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for (u16 i = 0; i < response_header.answer_count(); ++i) {
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auto& record = *(const DNSRecord*)(&((const u8*)response_header.payload())[offset]);
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dbgprintf("LookupServer: Answer #%u: (question: %s), type=%u, ttl=%u, length=%u, data=",
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i,
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question.characters(),
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record.type(),
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record.ttl(),
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record.data_length());
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offset += sizeof(DNSRecord) + record.data_length();
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if (record.type() == T_PTR) {
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int dummy = 0;
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auto name = parse_dns_name((const u8*)record.data(), dummy, record.data_length());
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dbgprintf("%s\n", name.characters());
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addresses.append(name);
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} else if (record.type() == T_A) {
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auto ipv4_address = IPv4Address((const u8*)record.data());
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dbgprintf("%s\n", ipv4_address.to_string().characters());
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addresses.append(ipv4_address.to_string());
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} else {
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dbgprintf("(unimplemented)\n");
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dbgprintf("LookupServer: FIXME: Handle record type %u\n", record.type());
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}
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// FIXME: Parse some other record types perhaps?
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}
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m_lookup_cache.set(hostname, { time(nullptr), record_type, addresses });
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return addresses;
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}
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