quic/qbone/qbone_packet_processor.h - quiche - Git at Google

 // 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.

 #ifndef QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_
 #define QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_

 #include <netinet/icmp6.h>
 #include <netinet/ip6.h>

 #include "absl/strings/string_view.h"
 #include "quic/core/quic_types.h"
 #include "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 {
  public:
   enum class Direction {
     // Packet is going from the QBONE client into the network behind the QBONE.
     FROM_OFF_NETWORK = 0,
     // Packet is going from the network begin QBONE to the client.
     FROM_NETWORK = 1
   };

   enum class ProcessingResult {
     OK = 0,
     SILENT_DROP = 1,
     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.
     ICMP_AND_TCP_RESET = 4,
   };

   class OutputInterface {
    public:
     virtual ~OutputInterface();

     virtual void SendPacketToClient(absl::string_view packet) = 0;
     virtual void SendPacketToNetwork(absl::string_view packet) = 0;
   };

   class StatsInterface {
    public:
     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 {
    public:
     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);

    protected:
     // 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().
     inline uint8_t TransportProtocolFromHeader(absl::string_view ipv6_header) {
       return ipv6_header[6];
     }
     inline QuicIpAddress SourceIpFromHeader(absl::string_view ipv6_header) {
       QuicIpAddress address;
       address.FromPackedString(&ipv6_header[8],
                                QuicIpAddress::kIPv6AddressSize);
       return address;
     }
     inline QuicIpAddress DestinationIpFromHeader(
         absl::string_view ipv6_header) {
       QuicIpAddress address;
       address.FromPackedString(&ipv6_header[24],
                                QuicIpAddress::kIPv6AddressSize);
       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;

  protected:
   // 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);

   inline 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_;

  private:
   // 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
 #endif  // QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_
	// 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.

	#ifndef QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_
	#define QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_

	#include <netinet/icmp6.h>
	#include <netinet/ip6.h>

	#include "absl/strings/string_view.h"
	#include "quic/core/quic_types.h"
	#include "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 {
	public:
	enum class Direction {
	// Packet is going from the QBONE client into the network behind the QBONE.
	FROM_OFF_NETWORK = 0,
	// Packet is going from the network begin QBONE to the client.
	FROM_NETWORK = 1
	};

	enum class ProcessingResult {
	OK = 0,
	SILENT_DROP = 1,
	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.
	ICMP_AND_TCP_RESET = 4,
	};

	class OutputInterface {
	public:
	virtual ~OutputInterface();

	virtual void SendPacketToClient(absl::string_view packet) = 0;
	virtual void SendPacketToNetwork(absl::string_view packet) = 0;
	};

	class StatsInterface {
	public:
	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 {
	public:
	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);

	protected:
	// 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().
	inline uint8_t TransportProtocolFromHeader(absl::string_view ipv6_header) {
	return ipv6_header[6];
	}
	inline QuicIpAddress SourceIpFromHeader(absl::string_view ipv6_header) {
	QuicIpAddress address;
	address.FromPackedString(&ipv6_header[8],
	QuicIpAddress::kIPv6AddressSize);
	return address;
	}
	inline QuicIpAddress DestinationIpFromHeader(
	absl::string_view ipv6_header) {
	QuicIpAddress address;
	address.FromPackedString(&ipv6_header[24],
	QuicIpAddress::kIPv6AddressSize);
	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;

	protected:
	// 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);

	inline 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_;

	private:
	// 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
	#endif // QUICHE_QUIC_QBONE_QBONE_PACKET_PROCESSOR_H_