Insane_DNS/include/insane_dns/util.h

185 lines
7.5 KiB
C++

/*
* BLT Memory Util for parsing DNS packets / BLT + ASIO simple packet sender.
* This software is unlikely to become part of BLT main but is provided under the BLT license (GPL 3).
* Copyright (C) 2023 Brett Terpstra, Et al
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef INSANE_DNS_UTIL_H
#define INSANE_DNS_UTIL_H
#include <insane_dns/constants.h>
#include <type_traits>
#include <asio.hpp>
#include <cstdint>
#include <functional>
#include <blt/std/memory.h>
using asio::ip::udp;
using asio::ip::tcp;
namespace blt
{
/**
* Basic parser for processing strings of bytes received from UDP sockets. This class provides a simple interface for efficiently copying the
* big endian bytes from the network into the little endian bytes required by x86 processors. The class also provides basic safety guarantees
* in the sense that the program will halt execution if reading the bytes would overflow the internal buffer.
*/
class byte_reader
{
private:
unsigned char* _data;
const size_t _size;
mutable size_t _current_byte;
public:
explicit byte_reader(unsigned char* data, size_t size, size_t start_offset): _data(data), _size(size), _current_byte(start_offset)
{}
/**
* Read the next byte in the data stream then increment the internal counter by 1
* @return the next byte in the array
*/
inline unsigned char& next() const
{
BLT_ASSERT(_current_byte < _size);
return _data[_current_byte++];
}
/**
* Reads data into the provided template parameter, reordering the byte into the correct little endian format
* @tparam T type to read (deduction is automatic)
* @param t variable reference to read into
*/
template<typename T>
inline void to(T& t) const
{
BLT_ASSERT(_current_byte + sizeof(T) <= _size);
// I hate little endian. I hate dealing with converting between endianness
// it is very easy to do it very slowly
// So I made BLT provide a simple interface to convert between bytes dependent on the platform
// for small integral types (16, 32, and 64) it will compile to 3 instructions using compiler intrinsics.
// Larger POD types are supported but will use std::reverse and therefore be slow.
blt::mem::fromBytes(&_data[_current_byte], t);
skip(sizeof(T));
}
/**
* Copy from the internal data buffer, advancing the internal stream, into the provided unsigned char array. *No reordering is done*
* @param out character array to write to
* @param size number of bytes to copy
*/
inline void copy(unsigned char*& out, size_t size) const
{
BLT_ASSERT(_current_byte + size < _size);
std::memcpy(out, &_data[_current_byte], size);
skip(size);
}
/**
* Skip bytes in the data stream, useful for skipping sections of the DNS packet we may not care about.
* @param s number of bytes to skip.
*/
inline void skip(size_t s = 1) const
{
_current_byte += s;
}
/**
* @return 1 past the last byte we wrote to, otherwise known as the next byte we will be writing to.
*/
inline size_t last() const
{
return _current_byte;
}
/**
* @return a pointer to a location in the internal buffer starting at last()
*/
inline unsigned char* from()
{
BLT_ASSERT(_current_byte < _size);
return &_data[_current_byte];
}
};
namespace network
{
/**
* Sends a simple UDP message to the provided host on the DNS port and outputs the response into the out buffer
* @param host host to send the message to
* @param in buffer to send
* @param in_size size of buffer
* @param out buffer to write to
* @param out_size size of data that was written. Make sure `out` has enough room for the packet.
*/
void sendUDPMessage(const std::string& host, const unsigned char* const& in, size_t in_size, blt::scoped_buffer<unsigned char>& out,
size_t& out_size)
{
asio::io_context io_context;
udp::endpoint receiver_endpoint(asio::ip::address::from_string(host), 53);
udp::socket socket(io_context);
socket.open(udp::v4());
socket.send_to(asio::const_buffers_1(in, in_size), receiver_endpoint);
udp::endpoint sender_endpoint;
out_size = socket.receive_from(asio::buffer(out.data(), out.size()), sender_endpoint);
}
/**
* Sends a simple TCP message to the provided host on the DNS port and outputs the response into the out buffer
* @param host host to send the message to
* @param in buffer to send
* @param in_size size of buffer
* @param out buffer to write to
* @param out_size size of data that was written. Make sure `out` has enough room for the packet.
*/
void sendTCPMessage(const std::string& host, const unsigned char* const& in, size_t in_size, blt::scoped_buffer<unsigned char>& out,
size_t& out_size)
{
asio::io_context io_context;
tcp::resolver resolver(io_context);
tcp::resolver::results_type endpoints = resolver.resolve(host, "53");
tcp::socket socket(io_context);
asio::connect(socket, endpoints);
asio::write(socket, asio::buffer(in, in_size));
out_size = socket.read_some(asio::buffer(out.data(), out.size()));
}
}
}
#endif //INSANE_DNS_UTIL_H
// these are no longer used, but I am keeping them around because they are useful and were not added to git
// template<class T>
// struct is_byte_ptr_type : std::integral_constant<bool,
// std::is_same_v<T, std::int8_t*> || std::is_same_v<T, std::uint8_t*> ||
// std::is_same_v<T, unsigned char*> || std::is_same_v<T, char*> || std::is_same_v<T, signed char*>>
// {
// };
//
// template<typename T>
// inline constexpr bool is_byte_ptr_type_v = is_byte_ptr_type<T>::value;
//
// template<typename IN, typename OUT>
// using messageFunction = std::function<void(const std::string&, const IN&, size_t, OUT&, size_t&)>;