227 lines
8.8 KiB
C++
227 lines
8.8 KiB
C++
/*
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* BLT Memory Util for parsing DNS packets / BLT + ASIO simple packet sender / BLT Type Name Demangler.
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* This software is unlikely to become part of BLT main but is provided under the BLT license (GPL 3).
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* Copyright (C) 2023 Brett Terpstra, Et al
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef INSANE_DNS_UTIL_H
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#define INSANE_DNS_UTIL_H
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#include <insane_dns/constants.h>
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#include <type_traits>
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#include <asio.hpp>
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#include <cstdint>
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#include <functional>
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#include <blt/std/memory.h>
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#include <blt/std/logging.h>
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#ifdef __GNUC__
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#include <cxxabi.h>
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#endif
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using asio::ip::udp;
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using asio::ip::tcp;
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namespace blt
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{
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/**
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* Basic parser for processing strings of bytes received from UDP sockets. This class provides a simple interface for efficiently copying the
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* big endian bytes from the network into the little endian bytes required by x86 processors. The class also provides basic safety guarantees
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* in the sense that the program will halt execution if reading the bytes would overflow the internal buffer.
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*/
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class byte_reader
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{
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private:
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unsigned char* _data;
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const size_t _size;
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mutable size_t _current_byte;
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public:
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explicit byte_reader(unsigned char* data, size_t size, size_t start_offset): _data(data), _size(size), _current_byte(start_offset)
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{}
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/**
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* Read the next byte in the data stream then increment the internal counter by 1
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* @return the next byte in the array
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*/
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inline unsigned char& next() const
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{
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BLT_ASSERT(_current_byte < _size);
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return _data[_current_byte++];
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}
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/**
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* Reads data into the provided template parameter, reordering the byte into the correct little endian format
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* @tparam T type to read (deduction is automatic)
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* @param t variable reference to read into
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*/
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template<typename T>
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inline void to(T& t) const
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{
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BLT_ASSERT(_current_byte + sizeof(T) <= _size);
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// I hate little endian. I hate dealing with converting between endianness
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// it is very easy to do it very slowly
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// So I made BLT provide a simple interface to convert between bytes dependent on the platform
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// for small integral types (16, 32, and 64) it will compile to 3 instructions using compiler intrinsics.
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// Larger POD types are supported but will use std::reverse and therefore be slow.
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blt::mem::fromBytes(&_data[_current_byte], t);
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skip(sizeof(T));
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}
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/**
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* Copy from the internal data buffer, advancing the internal stream, into the provided unsigned char array. *No reordering is done*
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* @param out character array to write to
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* @param size number of bytes to copy
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*/
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inline void copy(unsigned char*& out, size_t size) const
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{
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BLT_ASSERT(_current_byte + size < _size);
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std::memcpy(out, &_data[_current_byte], size);
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skip(size);
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}
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/**
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* Skip bytes in the data stream, useful for skipping sections of the DNS packet we may not care about.
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* @param s number of bytes to skip.
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*/
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inline void skip(size_t s = 1) const
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{
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_current_byte += s;
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}
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/**
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* @return 1 past the last byte we wrote to, otherwise known as the next byte we will be writing to.
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*/
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inline size_t last() const
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{
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return _current_byte;
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}
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/**
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* @return a pointer to a location in the internal buffer starting at last()
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*/
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inline unsigned char* from()
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{
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BLT_ASSERT(_current_byte < _size);
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return &_data[_current_byte];
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}
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};
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namespace network
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{
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/**
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* Sends a simple UDP message to the provided host on the DNS port and outputs the response into the out buffer
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* @param host host to send the message to
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* @param in buffer to send
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* @param in_size size of buffer
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* @param out buffer to write to
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* @param out_size size of data that was written. Make sure `out` has enough room for the packet.
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*/
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void sendUDPMessage(const std::string& host, const unsigned char* const& in, size_t in_size, blt::scoped_buffer<unsigned char>& out,
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size_t& out_size)
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{
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BLT_DEBUG("Sending UDP DNS request to '%s' of size %d", host.c_str(), in_size);
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asio::io_context io_context;
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udp::endpoint receiver_endpoint(asio::ip::address::from_string(host), 53);
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udp::socket socket(io_context);
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socket.open(udp::v4());
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socket.send_to(asio::const_buffers_1(in, in_size), receiver_endpoint);
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udp::endpoint sender_endpoint;
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out_size = socket.receive_from(asio::buffer(out.data(), out.size()), sender_endpoint);
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BLT_DEBUG("Received UDP DNS response from '%s' of size %d", host.c_str(), out_size);
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}
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/**
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* Sends a simple TCP message to the provided host on the DNS port and outputs the response into the out buffer
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* @param host host to send the message to
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* @param in buffer to send
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* @param in_size size of buffer
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* @param out buffer to write to
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* @param out_size size of data that was written. Make sure `out` has enough room for the packet.
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*/
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void sendTCPMessage(const std::string& host, const unsigned char* const& in, size_t in_size, blt::scoped_buffer<unsigned char>& out,
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size_t& out_size)
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{
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BLT_DEBUG("Sending TCP DNS request to '%s' of size %d", host.c_str(), in_size);
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asio::io_context io_context;
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tcp::resolver resolver(io_context);
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tcp::resolver::results_type endpoints = resolver.resolve(host, "53");
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tcp::socket socket(io_context);
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asio::connect(socket, endpoints);
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asio::write(socket, asio::buffer(in, in_size));
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out_size = socket.read_some(asio::buffer(out.data(), out.size()));
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BLT_DEBUG("Received TCP dns response from '%s' of size %d", host.c_str(), out_size);
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}
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}
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#ifdef __GNUC__
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/**
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* Attempts to demangle the type name of the provided template type
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* @tparam T
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* @return
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*/
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template<typename T>
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static BLT_CPP20_CONSTEXPR inline std::string type_name()
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{
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int status;
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std::string return_name = typeid(T).name();
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// only defined for GNU C++11?
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char *demangled_name = abi::__cxa_demangle(return_name.c_str(), nullptr, nullptr, &status);
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if (demangled_name == nullptr)
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return return_name;
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return_name = demangled_name;
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std::free(demangled_name);
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return return_name;
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}
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template<typename T>
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static BLT_CPP20_CONSTEXPR inline std::string is_UDP_or_TCP(){
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std::string type = "UDP";
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if (blt::string::contains(blt::type_name<T>(), "TCP"))
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type = "TCP";
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return type;
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}
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#endif
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}
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#endif //INSANE_DNS_UTIL_H
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// these are no longer used, but I am keeping them around because they are useful and were not added to git
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// template<class T>
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// struct is_byte_ptr_type : std::integral_constant<bool,
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// std::is_same_v<T, std::int8_t*> || std::is_same_v<T, std::uint8_t*> ||
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// std::is_same_v<T, unsigned char*> || std::is_same_v<T, char*> || std::is_same_v<T, signed char*>>
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// {
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// };
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//
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// template<typename T>
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// inline constexpr bool is_byte_ptr_type_v = is_byte_ptr_type<T>::value;
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//
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// template<typename IN, typename OUT>
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// using messageFunction = std::function<void(const std::string&, const IN&, size_t, OUT&, size_t&)>;
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