blob: ab7ca00737a595c0df9367b2582b84058e33bed2 [file] [log] [blame]
// Copyright (c) 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <netinet/icmp6.h>
#include <netinet/ip6.h>
#include "absl/strings/string_view.h"
#include "quiche/quic/core/quic_types.h"
#include "quiche/quic/platform/api/quic_ip_address.h"
namespace quic {
enum : size_t {
kIPv6HeaderSize = 40,
kICMPv6HeaderSize = sizeof(icmp6_hdr),
kTotalICMPv6HeaderSize = kIPv6HeaderSize + kICMPv6HeaderSize,
// QBONE packet processor accepts packets destined in either direction
// (client-to-network or network-to-client). It inspects them and makes
// decisions on whether they should be forwarded or dropped, replying with ICMP
// messages as appropriate.
class QbonePacketProcessor {
enum class Direction {
// Packet is going from the QBONE client into the network behind the QBONE.
// Packet is going from the network begin QBONE to the client.
enum class ProcessingResult {
OK = 0,
ICMP = 2,
// Equivalent to |SILENT_DROP| at the moment, but indicates that the
// downstream filter has buffered the packet and deferred its processing.
// The packet may be emitted at a later time.
DEFER = 3,
// In addition to sending an ICMP message, also send a TCP RST. This option
// requires the incoming packet to have been a valid TCP packet, as a TCP
// RST requires information from the current connection state to be
// well-formed.
// Send a TCP RST.
class OutputInterface {
virtual ~OutputInterface();
virtual void SendPacketToClient(absl::string_view packet) = 0;
virtual void SendPacketToNetwork(absl::string_view packet) = 0;
class StatsInterface {
virtual ~StatsInterface();
virtual void OnPacketForwarded(Direction direction) = 0;
virtual void OnPacketDroppedSilently(Direction direction) = 0;
virtual void OnPacketDroppedWithIcmp(Direction direction) = 0;
virtual void OnPacketDroppedWithTcpReset(Direction direction) = 0;
virtual void OnPacketDeferred(Direction direction) = 0;
// Allows to implement a custom packet filter on top of the filtering done by
// the packet processor itself.
class Filter {
virtual ~Filter();
// The main interface function. The following arguments are supplied:
// - |direction|, to indicate direction of the packet.
// - |full_packet|, which includes the IPv6 header and possibly the IPv6
// options that were understood by the processor.
// - |payload|, the contents of the IPv6 packet, i.e. a TCP, a UDP or an
// ICMP packet.
// - |icmp_header|, an output argument which allows the filter to specify
// the ICMP message with which the packet is to be rejected.
// The method is called only on packets which were already verified as valid
// IPv6 packets.
// The implementer of this method has four options to return:
// - OK will cause the filter to pass the packet through
// - SILENT_DROP will cause the filter to drop the packet silently
// - ICMP will cause the filter to drop the packet and send an ICMP
// response.
// - DEFER will cause the packet to be not forwarded; the filter is
// responsible for sending (or not sending) it later using |output|.
// Note that |output| should not be used except in the DEFER case, as the
// processor will perform the necessary writes itself.
virtual ProcessingResult FilterPacket(Direction direction,
absl::string_view full_packet,
absl::string_view payload,
icmp6_hdr* icmp_header,
OutputInterface* output);
// Helper methods that allow to easily extract information that is required
// for filtering from the |ipv6_header| argument. All of those assume that
// the header is of valid size, which is true for everything passed into
// FilterPacket().
uint8_t TransportProtocolFromHeader(absl::string_view ipv6_header) {
return ipv6_header[6];
QuicIpAddress SourceIpFromHeader(absl::string_view ipv6_header) {
QuicIpAddress address;
return address;
QuicIpAddress DestinationIpFromHeader(absl::string_view ipv6_header) {
QuicIpAddress address;
return address;
// |self_ip| is the IP address from which the processor will originate ICMP
// messages. |client_ip| is the expected IP address of the client, used for
// packet validation.
// |output| and |stats| are the visitor interfaces used by the processor.
// |output| gets notified whenever the processor decides to send a packet, and
// |stats| gets notified about any decisions that processor makes, without a
// reference to which packet that decision was made about.
QbonePacketProcessor(QuicIpAddress self_ip, QuicIpAddress client_ip,
size_t client_ip_subnet_length, OutputInterface* output,
StatsInterface* stats);
QbonePacketProcessor(const QbonePacketProcessor&) = delete;
QbonePacketProcessor& operator=(const QbonePacketProcessor&) = delete;
// Accepts an IPv6 packet and handles it accordingly by either forwarding it,
// replying with an ICMP packet or silently dropping it. |packet| will be
// modified in the process, by having the TTL field decreased.
void ProcessPacket(std::string* packet, Direction direction);
void set_filter(std::unique_ptr<Filter> filter) {
filter_ = std::move(filter);
void set_client_ip(QuicIpAddress client_ip) { client_ip_ = client_ip; }
void set_client_ip_subnet_length(size_t client_ip_subnet_length) {
client_ip_subnet_length_ = client_ip_subnet_length;
static const QuicIpAddress kInvalidIpAddress;
// Processes the header and returns what should be done with the packet.
// After that, calls an external packet filter if registered. TTL of the
// packet may be decreased in the process.
ProcessingResult ProcessIPv6HeaderAndFilter(std::string* packet,
Direction direction,
uint8_t* transport_protocol,
char** transport_data,
icmp6_hdr* icmp_header);
void SendIcmpResponse(icmp6_hdr* icmp_header,
absl::string_view original_packet,
Direction original_direction);
void SendTcpReset(absl::string_view original_packet,
Direction original_direction);
bool IsValid() const { return client_ip_ != kInvalidIpAddress; }
// IP address of the server. Used to send ICMP messages.
in6_addr self_ip_;
// IP address range of the VPN client.
QuicIpAddress client_ip_;
size_t client_ip_subnet_length_;
OutputInterface* output_;
StatsInterface* stats_;
std::unique_ptr<Filter> filter_;
// Performs basic sanity and permission checks on the packet, and decreases
// the TTL.
ProcessingResult ProcessIPv6Header(std::string* packet, Direction direction,
uint8_t* transport_protocol,
char** transport_data,
icmp6_hdr* icmp_header);
void SendResponse(Direction original_direction, absl::string_view packet);
} // namespace quic