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tcp_header.hpp
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tcp_header.hpp
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//
// tcp_header.hpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include <algorithm>
#include <istream>
#include <ostream>
#include <boost/endian/conversion.hpp>
#include <boost/format.hpp>
#include <iostream>
// 0 8 16 31
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Source Port | Destination Port |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Sequence Number |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Acknowledgment Number |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Offset| Res. | Flags | Window |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Checksum | Urgent Pointer |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Options | Padding |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
class tcp_header
{
private:
public:
enum
{
flag_FIN = 0x01,
flag_SYN = 0x02,
flag_RST = 0x04,
flag_PUSH = 0x08,
flag_ACK = 0x10,
flag_URG = 0x20,
};
tcp_header()
{
std::fill(raw_buff, raw_buff + sizeof(raw_buff), 0);
}
uint16_t get_sourceport() const {
return (raw_buff[0] << 8) + raw_buff[1];
}
void set_sourceport(uint16_t port) {
raw_buff[0] = port >> 8;
raw_buff[1] = port & 0xFF;
}
uint16_t get_destport() const {
return (raw_buff[2] << 8) + raw_buff[3];
}
void set_destport(uint16_t port) {
raw_buff[2] = port >> 8;
raw_buff[3] = port & 0xFF;
}
uint32_t get_seq_number() const {
return (raw_buff[4] << 24) + (raw_buff[5] << 16) + (raw_buff[6] << 8) + raw_buff[7];
}
void set_seq_number(uint32_t seq_number) {
raw_buff[4] = (seq_number >> 24) & 0xff;
raw_buff[5] = (seq_number >> 16) & 0xff;
raw_buff[6] = (seq_number >> 8) & 0xff;
raw_buff[7] = seq_number & 0xff;
}
uint32_t get_ack_number() const {
return (raw_buff[8] << 24) + (raw_buff[9] << 16) + (raw_buff[10] << 8) + raw_buff[11];
}
void set_ack_number(uint32_t ack_number) {
raw_buff[8] = (ack_number >> 24) & 0xff;
raw_buff[9] = (ack_number >> 16) & 0xff;
raw_buff[10] = (ack_number >> 8) & 0xff;
raw_buff[11] = ack_number & 0xff;
}
uint8_t get_header_len() const {
return raw_buff[12] >> 4;
}
void set_header_len(uint8_t header_len) {
raw_buff[12] = header_len << 4;
}
uint8_t get_flags() const {
return raw_buff[13];
}
void set_flags(uint8_t flags) {
raw_buff[13] = flags;
}
uint16_t get_window_size() const {
return (raw_buff[14] << 8) + raw_buff[15];
}
void set_window_size(uint16_t window_size) {
raw_buff[14] = window_size >> 8;
raw_buff[15] = window_size & 0xff;
}
void set_checksum(uint16_t checksum)
{
raw_buff[16] = checksum >> 8;
raw_buff[17] = checksum & 0xff;
}
uint16_t get_urgent_ptr() const {
return (raw_buff[18] << 8) + raw_buff[19];;
}
void set_urgent_ptr(uint16_t urgent_ptr) {
raw_buff[18] = urgent_ptr >> 8;
raw_buff[19] = urgent_ptr & 0xff;
}
void set_options()
{
raw_buff[20] = 0x02;
raw_buff[21] = 0x04;
raw_buff[22] = 0x05;
raw_buff[23] = 0xb4;
}
friend std::istream &operator>>(std::istream &is, tcp_header &header)
{
return is.read(reinterpret_cast<char *>(&header.raw_buff), 24);
}
friend std::ostream &operator<<(std::ostream &os, const tcp_header &header)
{
return os.write(reinterpret_cast<const char *>(&header.raw_buff), 24);
}
template <typename Iterator> friend void compute_checksum(tcp_header &header, Iterator body_begin, Iterator body_end);
void set_dst_ip(boost::asio::ip::address dst_ip) {
destination_addr = dst_ip;
}
void set_src_ip(boost::asio::ip::address src_ip) {
source_addr = src_ip;
}
private:
unsigned char raw_buff[24] = {0};
boost::asio::ip::address destination_addr;
boost::asio::ip::address source_addr;
};
template <typename Iterator> void compute_checksum(tcp_header &header, Iterator body_begin, Iterator body_end)
{
unsigned int sum = 0;
struct ip_pseudo_header
{
uint32_t sourceip;
uint32_t destip;
uint8_t zero;
uint8_t tcp_prot;
uint16_t tcp_length;
};
unsigned char raw_pseudo_header[12] = {0};
raw_pseudo_header[0] = header.source_addr.to_v4().to_bytes()[0];
raw_pseudo_header[1] = header.source_addr.to_v4().to_bytes()[1];
raw_pseudo_header[2] = header.source_addr.to_v4().to_bytes()[2];
raw_pseudo_header[3] = header.source_addr.to_v4().to_bytes()[3];
raw_pseudo_header[4] = header.destination_addr.to_v4().to_bytes()[0];
raw_pseudo_header[5] = header.destination_addr.to_v4().to_bytes()[1];
raw_pseudo_header[6] = header.destination_addr.to_v4().to_bytes()[2];
raw_pseudo_header[7] = header.destination_addr.to_v4().to_bytes()[3];
raw_pseudo_header[9] = 0x06;
raw_pseudo_header[10] = 0;
raw_pseudo_header[11] = 24; // tcp_length
for (int i = 0; i < 12; i+=2)
{
/*if (i % 4 == 0)
{
std::cout << "\n";
}
std::cout << boost::format("%04x") % ((raw_pseudo_header[i] << 8) + raw_pseudo_header[i+1]);
*/
sum += ((raw_pseudo_header[i] << 8) +raw_pseudo_header[i+1]);
}
for (int i = 0; i < 24; i+=2)
{
/*if (i % 4 == 0)
{
std::cout << "\n";
}
std::cout << boost::format("%04x") % ((header.raw_buff[i] << 8) + header.raw_buff[i+1]);
*/
sum += ((header.raw_buff[i] << 8) + header.raw_buff[i+1]);
}
while (sum>>16) {
sum = (sum & 0xffff) + (sum >> 16);
}
sum = ~sum;
header.set_checksum(sum);
}