protocol_util.h

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// Copyright (C) 2013-2021 Internet Systems Consortium, Inc. ("ISC")
//
// 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/.

#ifndef PROTOCOL_UTIL_H
#define PROTOCOL_UTIL_H

#include <dhcp/pkt4.h>
#include <util/buffer.h>

#include <stdint.h>

namespace isc {
namespace dhcp {

class InvalidPacketHeader : public Exception {
public:
    InvalidPacketHeader(const char* file, size_t line, const char* what) :
        isc::Exception(file, line, what) { };
};

static const size_t ETHERNET_HEADER_LEN = 14;
static const size_t ETHERNET_PACKET_TYPE_OFFSET = 12;
static const uint16_t ETHERNET_TYPE_IP = 0x0800;

static const size_t MIN_IP_HEADER_LEN = 20;
static const size_t IP_FLAGS_OFFSET = 6;
static const size_t IP_PROTO_TYPE_OFFSET = 9;
static const size_t IP_SRC_ADDR_OFFSET = 12;
static const size_t IP_DEST_ADDR_OFFSET = 16;

static const size_t UDP_HEADER_LEN = 8;
static const size_t UDP_DEST_PORT = 2;

void decodeEthernetHeader(util::InputBuffer& buf, Pkt4Ptr& pkt);

void decodeIpUdpHeader(util::InputBuffer& buf, Pkt4Ptr& pkt);

void writeEthernetHeader(const Pkt4Ptr& pkt,
                         util::OutputBuffer& out_buf);

void writeIpUdpHeader(const Pkt4Ptr& pkt, util::OutputBuffer& out_buf);

uint16_t calcChecksum(const uint8_t* buf, const uint32_t buf_size,
                      uint32_t sum = 0);

}
}
#endif // PROTOCOL_UTIL_H