WireGuard for MacOS (#248)

* WireGuard for MacOS
* Fix openvpn block-outside-dns

client/mozilla/dnspingsender.cpp

@@ -0,0 +1,117 @@
+/* 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));
+  }
+}