117 lines
3.3 KiB
C++
117 lines
3.3 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
#include "dnspingsender.h"
|
|
|
|
#include <string.h>
|
|
|
|
#include <QNetworkDatagram>
|
|
#include <QtEndian>
|
|
|
|
#include "leakdetector.h"
|
|
#include "logger.h"
|
|
|
|
constexpr const quint16 DNS_PORT = 53;
|
|
|
|
// A quick and dirty DNS Header structure definition from RFC1035,
|
|
// Section 4.1.1: Header Section format.
|
|
struct dnsHeader {
|
|
quint16 id;
|
|
quint16 flags;
|
|
quint16 qdcount;
|
|
quint16 ancount;
|
|
quint16 nscount;
|
|
quint16 arcount;
|
|
};
|
|
|
|
// Bit definitions for the DNS flags field.
|
|
#define DNS_FLAG_QR 0x8000
|
|
#define DNS_FLAG_OPCODE 0x7800
|
|
#define DNS_FLAG_OPCODE_QUERY (0x0 << 11)
|
|
#define DNS_FLAG_OPCODE_IQUERY (0x1 << 11)
|
|
#define DNS_FLAG_OPCODE_STATUS (0x2 << 11)
|
|
#define DNS_FLAG_AA 0x0400
|
|
#define DNS_FLAG_TC 0x0200
|
|
#define DNS_FLAG_RD 0x0100
|
|
#define DNS_FLAG_RA 0x0080
|
|
#define DNS_FLAG_Z 0x0070
|
|
#define DNS_FLAG_RCODE 0x000F
|
|
#define DNS_FLAG_RCODE_NO_ERROR (0x0 << 0)
|
|
#define DNS_FLAG_RCODE_FORMAT_ERROR (0x1 << 0)
|
|
#define DNS_FLAG_RCODE_SERVER_FAILURE (0x2 << 0)
|
|
#define DNS_FLAG_RCODE_NAME_ERROR (0x3 << 0)
|
|
#define DNS_FLAG_RCODE_NOT_IMPLEMENTED (0x4 << 0)
|
|
#define DNS_FLAG_RCODE_REFUSED (0x5 << 0)
|
|
|
|
namespace {
|
|
Logger logger("DnsPingSender");
|
|
}
|
|
|
|
DnsPingSender::DnsPingSender(const QHostAddress& source, QObject* parent)
|
|
: PingSender(parent) {
|
|
MZ_COUNT_CTOR(DnsPingSender);
|
|
|
|
if (source.isNull()) {
|
|
m_socket.bind();
|
|
} else {
|
|
m_socket.bind(source);
|
|
}
|
|
|
|
connect(&m_socket, &QUdpSocket::readyRead, this, &DnsPingSender::readData);
|
|
}
|
|
|
|
DnsPingSender::~DnsPingSender() { MZ_COUNT_DTOR(DnsPingSender); }
|
|
|
|
void DnsPingSender::sendPing(const QHostAddress& dest, quint16 sequence) {
|
|
QByteArray packet;
|
|
|
|
// Assemble a DNS query header.
|
|
struct dnsHeader header;
|
|
memset(&header, 0, sizeof(header));
|
|
header.id = qToBigEndian<quint16>(sequence);
|
|
header.flags = qToBigEndian<quint16>(DNS_FLAG_OPCODE_QUERY);
|
|
header.qdcount = qToBigEndian<quint16>(1);
|
|
header.ancount = 0;
|
|
header.nscount = 0;
|
|
header.arcount = 0;
|
|
packet.append(reinterpret_cast<char*>(&header), sizeof(header));
|
|
|
|
// Add a query for the root nameserver: {<root>, type A, class IN}
|
|
const char query[] = {0x00, 0x00, 0x01, 0x00, 0x01};
|
|
packet.append(query, sizeof(query));
|
|
|
|
// Send the datagram.
|
|
m_socket.writeDatagram(packet, dest, DNS_PORT);
|
|
}
|
|
|
|
void DnsPingSender::readData() {
|
|
while (m_socket.hasPendingDatagrams()) {
|
|
QNetworkDatagram reply = m_socket.receiveDatagram();
|
|
if (!reply.isValid()) {
|
|
break;
|
|
}
|
|
|
|
// Extract the header from the DNS response.
|
|
QByteArray payload = reply.data();
|
|
struct dnsHeader header;
|
|
if (payload.length() < static_cast<int>(sizeof(header))) {
|
|
logger.debug() << "Received bogus DNS reply: truncated header";
|
|
continue;
|
|
}
|
|
memcpy(&header, payload.constData(), sizeof(header));
|
|
|
|
// Perfom some checks to ensure this is the reply we were expecting.
|
|
quint16 flags = qFromBigEndian<quint16>(header.flags);
|
|
if ((flags & DNS_FLAG_QR) == 0) {
|
|
logger.debug() << "Received bogus DNS reply: QR == query";
|
|
continue;
|
|
}
|
|
if ((flags & DNS_FLAG_OPCODE) != DNS_FLAG_OPCODE_QUERY) {
|
|
logger.debug() << "Received bogus DNS reply: OPCODE != query";
|
|
continue;
|
|
}
|
|
|
|
emit recvPing(qFromBigEndian<quint16>(header.id));
|
|
}
|
|
}
|