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Insane_DNS
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move buffer to a util file, commented, also create a constants file

main
Brett 2023-10-26 16:02:34 -04:00
parent 41019ddcf2
commit 705c775c27
8 changed files with 181 additions and 62 deletions
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@ -59,3 +59,5 @@
7309 7612 1698284273630763380 insane_dns ff5ae500893d0be1
5 7368 1698284653019154297 CMakeFiles/insane_dns.dir/src/main.cpp.o 727da43cdbc82421
7369 7621 1698284653283151767 insane_dns ff5ae500893d0be1
2 2997 1698338548693635693 CMakeFiles/insane_dns.dir/src/main.cpp.o 727da43cdbc82421
2997 3087 1698338548789636298 insane_dns ff5ae500893d0be1

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cmake-build-debug/Testing/Temporary/LastTest.log
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@ -1,3 +1,3 @@
Start testing: Oct 25 21:44 EDT
Start testing: Oct 26 12:42 EDT
----------------------------------------------------------
End testing: Oct 25 21:44 EDT
End testing: Oct 26 12:42 EDT

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include/insane_dns/constants.h Normal file
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@ -0,0 +1,30 @@
/*
* Global constants file.
* Copyright (C) 2023 Brett Terpstra
*
* 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_CONSTANTS_H
#define INSANE_DNS_CONSTANTS_H
/*
* --------------------------------------------
* | Magic Number Constants |
* --------------------------------------------
*/
/** DNS header data offset. This is the first byte that isn't a header value (should be question label length octet) */
static constexpr size_t DNS_HEADER_END = 12;
#endif //INSANE_DNS_CONSTANTS_H

112
include/insane_dns/util.h Normal file
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@ -0,0 +1,112 @@
/*
* BLT Memory Util for parsing DNS packets.
* This software is unlikely to become part of BLT main but is provided under the BLT license (GPL 3).
* Copyright (C) 2023 Brett Terpstra
*
* 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>
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 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 = DNS_HEADER_END;
public:
explicit byte_reader(unsigned char* data, size_t size): _data(data), _size(size)
{}
/**
* 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];
}
};
}
#endif //INSANE_DNS_UTIL_H

95
src/main.cpp
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@ -17,37 +17,63 @@
#include <type_traits>
#include <unordered_set>
#include "ip.h"
#include "insane_dns/util.h"
/**
/*
* ----------------------------
* | CONFIG |
* ----------------------------
*/
// should we strictly match results? ie block *wikipedia.org* or just wikipedia.org?
/** should we strictly match results? ie block `*wikipedia.org*` or just `wikipedia.org`? */
static constexpr bool STRICT_MATCHING = false;
// true -> only match A records ; false -> match any named record (configure with NON_STRICT_REPLACE_ALL)
static constexpr bool STRICT_FILTERING = false;
// true -> match all records ; false -> match only records we might want to replace (A, AAAA, CNAME)
static constexpr bool NON_STRICT_REPLACE_ALL = true;
// DNS server to use for forwarding to / resolving DNS requests
/** DNS server to use for forwarding to / resolving DNS requests */
static inline constexpr std::string DNS_SERVER_IP()
{
return "8.8.8.8";
}
// replacement IP address. Make sure this is a 4 octet string seperated by .
/** replacement IP address. Make sure this is a 4 octet string seperated by `.` */
static inline constexpr IPAddress REPLACEMENT_IP()
{
return {"139.57.100.6"};
}
/**
* List of disallowed domains.
* Note: if you are using STRICT_MATCHING=false it will not match to the root domain.
* Eg it will match `*en.wikipedia.org*` NOT `*wikipedia.org*`
*/
static const std::unordered_set<std::string> DISALLOWED_DOMAINS{
"en.wikipedia.org",
"tpgc.me",
"zombo.com"
};
/*
* -----------------------------------
* | Do Not Change |
* -----------------------------------
*/
// these features were planned but not added because I realized you guys won't care or give extra marks which broke my obsession with it
// so uhh don't change em otherwise the code will break :3
/** true -> only match A records ; false -> match any named record (configure with NON_STRICT_REPLACE_ALL) */
static constexpr bool STRICT_FILTERING = true;
/** true -> match all records ; false -> match only records we might want to replace (A, AAAA, CNAME) */
static constexpr bool NON_STRICT_REPLACE_ALL = true;
// was going to add TCP and ad blocking support
// that also isn't going to happen now.
/** list of web address to download the ad block lists from */
static constexpr std::vector<std::string> BLOCK_LISTS{};
/** true -> block ad DNS requests ; false -> do nothing */
static constexpr bool BLOCK_ADS = false;
/** true -> send back the REPLACEMENT_IP() ; false -> send back a fail state in the DNS request. */
static constexpr bool REDIRECT_ADS = true;
// 5F826B
// DNS data contains:
// 2 bytes for transaction id
// 2 bytes for flags
@ -71,57 +97,6 @@ static const std::unordered_set<std::string> DISALLOWED_DOMAINS{
// 2 byte for length of data
// (lengthy) byte for data
class byte_reader
{
private:
unsigned char* data;
mutable size_t current_byte = 0;
public:
explicit byte_reader(unsigned char* data): data(data)
{
reset();
}
inline void reset() const
{
// magic number for end of header
current_byte = 12;
}
inline unsigned char& next() const
{
return data[current_byte++];
}
template<typename T>
inline void to(T& t) const
{
blt::mem::fromBytes(&data[current_byte], t);
skip(sizeof(T));
}
inline void copy(unsigned char*& out, size_t size) const
{
std::memcpy(out, &data[current_byte], size);
current_byte += size;
}
inline void skip(size_t s = 1) const
{
current_byte += s;
}
inline size_t last() const
{
return current_byte;
}
inline unsigned char* from()
{
return &data[current_byte];
}
};
class send_buffer;
class question
@ -376,7 +351,7 @@ int main()
uint16_t num_of_answers;
blt::mem::fromBytes(&mod_recv_buf[6], num_of_answers);
byte_reader reader2(mod_recv_buf.data());
byte_reader reader2(mod_recv_buf.data(), mod_recv_buf.size());
BLT_INFO("Bytes answered %d with %d answers", out_bytes, num_of_answers);