C++ mapの使い方

key, valueの連想配列class

struct Person {
    public:
        Person(const string &name, int height)
            : m_name(name)
            , m_height(height)
            {}
    public:
        string m_name;
        int m_height;
}

    ...
    map<Person, int> mp;
    Person p("aaa", 180);
    mp[p] = 123;

c++ cstdint

符号付き、符号なしで型の指定ができる

int8_t、int16_t、int32_t、int64_t、uint8_t、uint16_t、uint32_t、uint64_t、int_fast8_t、int_fast16_t、int_fast32_t、int_fast64_t、uint_fast8_t、uint_fast16_t、uint_fast32_t、uint_fast64_t、int_least8_t、int_least16_t、int_least32_t、int_least64_t、uint_least8_t、uint_least16_t、uint_least32_t、uint_least64_t、intmax_t、uintmax_t、intptr_t、uintptr_t

それにしても多いですね

[bitcoin]Signetとは?

Signetは、Bitcoinのテストネットとは異なり、特定のプロジェクトや開発者が制御できる独自のテストネットワーク
cmd, faucet, addr, passwordなどのオプションがある

getcoins.py

import argparse
import io
import requests
import subprocess
import sys
import xml.etree.ElementTree

DEFAULT_GLOBAL_FAUCET = 'https://signetfaucet.com/claim'
DEFAULT_GLOBAL_CAPTCHA = 'https://signetfaucet.com/captcha'
GLOBAL_FIRST_BLOCK_HASH = '00000086d6b2636cb2a392d45edc4ec544a10024d30141c9adf4bfd9de533b53'

# braille unicode block
BASE = 0x2800
BIT_PER_PIXEL = [
    [0x01, 0x08],
    [0x02, 0x10],
    [0x04, 0x20],
    [0x40, 0x80],
]
BW = 2
BH = 4

# imagemagick or compatible fork (used for converting SVG)
CONVERT = 'convert'

class PPMImage:
    '''
    Load a PPM image (Pillow-ish API).
    '''
    def __init__(self, f):
        if f.readline() != b'P6\n':
            raise ValueError('Invalid ppm format: header')
        line = f.readline()
        (width, height) = (int(x) for x in line.rstrip().split(b' '))
        if f.readline() != b'255\n':
            raise ValueError('Invalid ppm format: color depth')
        data = f.read(width * height * 3)
        stride = width * 3
        self.size = (width, height)
        self._grid = [[tuple(data[stride * y + 3 * x:stride * y + 3 * (x + 1)]) for x in range(width)] for y in range(height)]

    def getpixel(self, pos):
        return self._grid[pos[1]][pos[0]]

def print_image(img, threshold=128):
    '''Print black-and-white image to terminal in braille unicode characters.'''
    x_blocks = (img.size[0] + BW - 1) // BW
    y_blocks = (img.size[1] + BH - 1) // BH

    for yb in range(y_blocks):
        line = []
        for xb in range(x_blocks):
            ch = BASE
            for y in range(BH):
                for x in range(BW):
                    try:
                        val = img.getpixel((xb * BW + x, yb * BH + y))
                    except IndexError:
                        pass
                    else:
                        if val[0] < threshold:
                            ch |= BIT_PER_PIXEL[y][x]
            line.append(chr(ch))
        print(''.join(line))

parser = argparse.ArgumentParser(description='Script to get coins from a faucet.', epilog='You may need to start with double-dash (--) when providing bitcoin-cli arguments.')
parser.add_argument('-c', '--cmd', dest='cmd', default='bitcoin-cli', help='bitcoin-cli command to use')
parser.add_argument('-f', '--faucet', dest='faucet', default=DEFAULT_GLOBAL_FAUCET, help='URL of the faucet')
parser.add_argument('-g', '--captcha', dest='captcha', default=DEFAULT_GLOBAL_CAPTCHA, help='URL of the faucet captcha, or empty if no captcha is needed')
parser.add_argument('-a', '--addr', dest='addr', default='', help='Bitcoin address to which the faucet should send')
parser.add_argument('-p', '--password', dest='password', default='', help='Faucet password, if any')
parser.add_argument('-n', '--amount', dest='amount', default='0.001', help='Amount to request (0.001-0.1, default is 0.001)')
parser.add_argument('-i', '--imagemagick', dest='imagemagick', default=CONVERT, help='Path to imagemagick convert utility')
parser.add_argument('bitcoin_cli_args', nargs='*', help='Arguments to pass on to bitcoin-cli (default: -signet)')

args = parser.parse_args()

if args.bitcoin_cli_args == []:
    args.bitcoin_cli_args = ['-signet']


def bitcoin_cli(rpc_command_and_params):
    argv = [args.cmd] + args.bitcoin_cli_args + rpc_command_and_params
    try:
        return subprocess.check_output(argv).strip().decode()
    except FileNotFoundError:
        raise SystemExit(f"The binary {args.cmd} could not be found")
    except subprocess.CalledProcessError:
        cmdline = ' '.join(argv)
        raise SystemExit(f"-----\nError while calling {cmdline} (see output above).")


if args.faucet.lower() == DEFAULT_GLOBAL_FAUCET:
    # Get the hash of the block at height 1 of the currently active signet chain
    curr_signet_hash = bitcoin_cli(['getblockhash', '1'])
    if curr_signet_hash != GLOBAL_FIRST_BLOCK_HASH:
        raise SystemExit('The global faucet cannot be used with a custom Signet network. Please use the global signet or setup your custom faucet to use this functionality.\n')
else:
    # For custom faucets, don't request captcha by default.
    if args.captcha == DEFAULT_GLOBAL_CAPTCHA:
        args.captcha = ''

if args.addr == '':
    # get address for receiving coins
    args.addr = bitcoin_cli(['getnewaddress', 'faucet', 'bech32'])

data = {'address': args.addr, 'password': args.password, 'amount': args.amount}

# Store cookies
# for debugging: print(session.cookies.get_dict())
session = requests.Session()

if args.captcha != '': # Retrieve a captcha
    try:
        res = session.get(args.captcha)
        res.raise_for_status()
    except requests.exceptions.RequestException as e:
        raise SystemExit(f"Unexpected error when contacting faucet: {e}")

    # Size limitation
    svg = xml.etree.ElementTree.fromstring(res.content)
    if svg.attrib.get('width') != '150' or svg.attrib.get('height') != '50':
        raise SystemExit("Captcha size doesn't match expected dimensions 150x50")

    # Convert SVG image to PPM, and load it
    try:
        rv = subprocess.run([args.imagemagick, 'svg:-', '-depth', '8', 'ppm:-'], input=res.content, check=True, capture_output=True)
    except FileNotFoundError:
        raise SystemExit(f"The binary {args.imagemagick} could not be found. Please make sure ImageMagick (or a compatible fork) is installed and that the correct path is specified.")

    img = PPMImage(io.BytesIO(rv.stdout))

    # Terminal interaction
    print_image(img)
    print(f"Captcha from URL {args.captcha}")
    data['captcha'] = input('Enter captcha: ')

try:
    res = session.post(args.faucet, data=data)
except Exception:
    raise SystemExit(f"Unexpected error when contacting faucet: {sys.exc_info()[0]}")

# Display the output as per the returned status code
if res:
    # When the return code is in between 200 and 400 i.e. successful
    print(res.text)
elif res.status_code == 404:
    print('The specified faucet URL does not exist. Please check for any server issues/typo.')
elif res.status_code == 429:
    print('The script does not allow for repeated transactions as the global faucet is rate-limitied to 1 request/IP/day. You can access the faucet website to get more coins manually')
else:
    print(f'Returned Error Code {res.status_code}\n{res.text}\n')
    print('Please check the provided arguments for their validity and/or any possible typo.')

CMakeの使い方2

good_morning.hpp

#ifndef GOOD_MORNING_H
#define GOOD_MORNING_H

void good_morning();

#endif

good_morning.cpp

#include <iostream>
#include "good_morning.hpp"

void good_morning() {
    std::cout << "Good Monring!" << std::endl;
}

main.cpp

#include "hello.hpp"
#include "good_morning.hpp"

int main(){
    hello();
    good_morning();
}

$ g++ -c hello.cpp good_morning.cpp
$ ar rvs libgreetings.a hello.o good_morning.o
ar: creating libgreetings.a
a – hello.o
a – good_morning.o
$ g++ main.cpp libgreetings.a
$ ./a.out
Hello!
Good Monring!

CMakeの使い方

main.cpp

#include "hello.hpp"

int main(){
    hello();
}

hello.hpp

#ifndef HELLO_H
#define HELLO_H

void hello();

#endif

hello.cpp

#include <iostream>
#include "hello.hpp"

void hello() {
    std::cout << "Hello!" << std::endl;
}

### g++でビルドする場合
$ g++ -c main.cpp hello.cpp
$ g++ -o a.out main.o hello.o
$ ./a.out
Hello!

### CMake
CMakeLists.txtを作成する

CMakeLists.txt

# CMakeバージョン
cmake_minimum_required(VERSION 3.13)
# プロジェクト名と使用する言語
project(test_cmake CXX)
add_executable(a.out main.cpp hello.cpp)

CMakeを使ってビルドする際は、ビルド専用のディレクトリを作成し、その中で行う
$ ls
CMakeLists.txt hello.cpp hello.hpp main.cpp
$ cmake -S . -B build
$ tree
.
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ │ ├── 3.22.1
│ │ │ ├── CMakeCXXCompiler.cmake
│ │ │ ├── CMakeDetermineCompilerABI_CXX.bin
│ │ │ ├── CMakeSystem.cmake
│ │ │ └── CompilerIdCXX
│ │ │ ├── a.out
│ │ │ ├── CMakeCXXCompilerId.cpp
│ │ │ └── tmp
│ │ ├── a.out.dir
│ │ │ ├── build.make
│ │ │ ├── cmake_clean.cmake
│ │ │ ├── compiler_depend.make
│ │ │ ├── compiler_depend.ts
│ │ │ ├── DependInfo.cmake
│ │ │ ├── depend.make
│ │ │ ├── flags.make
│ │ │ ├── link.txt
│ │ │ └── progress.make
│ │ ├── cmake.check_cache
│ │ ├── CMakeDirectoryInformation.cmake
│ │ ├── CMakeOutput.log
│ │ ├── CMakeTmp
│ │ ├── Makefile2
│ │ ├── Makefile.cmake
│ │ ├── progress.marks
│ │ └── TargetDirectories.txt
│ ├── cmake_install.cmake
│ └── Makefile
├── CMakeLists.txt
├── hello.cpp
├── hello.hpp
└── main.cpp

[Python] import liefとは?

liefはPE、ELFなどの実行ファイルをパースし、一部のレコードの編集を行うためのライブラリ
– 実行ファイルの一部のレコードを編集した上で新しい実行ファイルとして書き出し
– パース可能な実行ファイルフォーマットが多い
– pefile, pyelftoolsなどがあった

### LIEFのインストール(ubutu22.04)
$ git clone https://github.com/lief-project/LIEF.git
$ cd LIEF && mkdir build && cd build
$ sudo apt update
$ sudo apt install cmake
$ sudo apt install ninja-build
※ninjaはbuildを高速化するツール。よくオープンソースのbuildなどに使われる。CPUを効率的に使用しており、複数コアのCPUだと特に速くなる。
※cmakeはコンパイラに依存しない自動化ツール
$ cmake -DLIEF_PYTHON_API=on -DPYTHON_VERSION=3.6 -DCMAKE_BUILD_TYPE=Release -DLIEF_TESTS=on -GNinja ..
$ cd api/python
$ python3
Python 3.10.12 (main, Nov 20 2023, 15:14:05) [GCC 11.4.0] on linux
Type “help”, “copyright”, “credits” or “license” for more information.
>>> import lief
Traceback (most recent call last):
File ““, line 1, in
ModuleNotFoundError: No module named ‘lief’
>>> exit()

う〜ん、よくわかりませんね。

symbol-check.py

import sys
import lief

[Shell] set -eとは

set -e とはコマンドの実行結果がエラー(= 終了ステータスが 0 以外)になった時にシェルスクリプトを自動的に中断させる機能
条件文(&& や || を含む)と共に使うシェル関数は set -e の効果が無効になる

contrib/devtools/split-debug.sh.in

set -e
if [ $# -ne 3 ];
    then echo "usage: $0 <input> <stripped-binary> <debug-binary>"
fi

Virtual Memory(仮想メモリ)とは?

自分の能力を超えて仮想的な記憶領域を得ること
容量不足時にSSD/HDDなどに書き出す
e.g. 使用していないときはSSDに保存しておいて、使用時に取り出すなど

devtools/security-check.py
 L R, W, Xの意味がよくわかりませんね。
 L ARCH.PPC64 はPowerPCのことのように見えるが何をやっているか不明

def check_ELF_separate_code(binary):
    '''
    Check that sections are appropriately separated in virtual memory,
    based on their permissions. This checks for missing -Wl,-z,separate-code
    and potentially other problems.
    '''
    R = lief.ELF.SEGMENT_FLAGS.R
    W = lief.ELF.SEGMENT_FLAGS.W
    E = lief.ELF.SEGMENT_FLAGS.X
    EXPECTED_FLAGS = {
        # Read + execute
        '.init': R | E,
        '.plt': R | E,
        '.plt.got': R | E,
        '.plt.sec': R | E,
        '.text': R | E,
        '.fini': R | E,
        # Read-only data
        '.interp': R,
        '.note.gnu.property': R,
        '.note.gnu.build-id': R,
        '.note.ABI-tag': R,
        '.gnu.hash': R,
        '.dynsym': R,
        '.dynstr': R,
        '.gnu.version': R,
        '.gnu.version_r': R,
        '.rela.dyn': R,
        '.rela.plt': R,
        '.rodata': R,
        '.eh_frame_hdr': R,
        '.eh_frame': R,
        '.qtmetadata': R,
        '.gcc_except_table': R,
        '.stapsdt.base': R,
        # Writable data
        '.init_array': R | W,
        '.fini_array': R | W,
        '.dynamic': R | W,
        '.got': R | W,
        '.data': R | W,
        '.bss': R | W,
    }
    if binary.header.machine_type == lief.ELF.ARCH.PPC64:
        # .plt is RW on ppc64 even with separate-code
        EXPECTED_FLAGS['.plt'] = R | W
    # For all LOAD program headers get mapping to the list of sections,
    # and for each section, remember the flags of the associated program header.
    flags_per_section = {}
    for segment in binary.segments:
        if segment.type ==  lief.ELF.SEGMENT_TYPES.LOAD:
            for section in segment.sections:
                flags_per_section[section.name] = segment.flags
    # Spot-check ELF LOAD program header flags per section
    # If these sections exist, check them against the expected R/W/E flags
    for (section, flags) in flags_per_section.items():
        if section in EXPECTED_FLAGS:
            if int(EXPECTED_FLAGS[section]) != int(flags):
                return False
    return True

[C++] ファイルの分割

C++におけるファイルの分割はクラス定義単位で行う

### ヘッダファイル
マクロ定義、型定義、プロトタイプ宣言の3つを書くのが基本
C++ではクラスを利用するには、そのクラスが提供するヘッダファイルを取り込む必要がある
以下のようなファイルがあったとする

class POS {
    private:
        int x;
        int y;
    
    public:
        POS();
        int setPos(int tmpx, int tmpy);
}

POS::POS(){
    x = 0;
    y = 0;
}

int POS::setPos(int tmpx, int tmpy){
    x = tmpx;
    y = tmpy;
    
    return 0;
}

これを分割する場合

POS.h

#ifndef POS_H
#define POS_H

class POS {
    private:
        int x;
        int y;
    
    public:
        POS();
        int setPos(int tmpx, int tmpy);
}

#endif

POS.cpp

#include "POS.h"

POS::POS(){
    x = 0;
    y = 0;
}

int POS::setPos(int tmpx, int tmpy){
    x = tmpx;
    y = tmpy;
    
    return 0;
}

つまり、最初にheader情報を見て、全体の流れを理解してからソースファイルを見ていくのね。※以前はcppを先に見て、.hは付加情報かと思っていました…orz

HeadersSyncState::ProcessingResult HeadersSyncState::ProcessNextHeaders(const
std::vector& received_headers, const bool full_headers_message)
で、ProcessingResult ProcessNextHeaders となっているのは、headerssync.hで、ProcessingResultの構造体を示していたので、このProcessingResultの型で返却して欲しい という書き方なのね。

struct ProcessingResult {
        std::vector<CBlockHeader> pow_validated_headers;
        bool success{false};
        bool request_more{false};
    };

[bitcoin] headerssync-paramsって何?

Readmeを読むと以下のように書いている
A script to generate optimal parameters for the headerssync module (src/headerssync.cpp). It takes no command-line
options, as all its configuration is set at the top of the file. It runs many times faster inside PyPy. Invocation:
つまり、node間でのヘッダー情報のやり取りのことだ。c++ファイルのヘッダではない。stateで、 PRESYNC、REDOWNLOAD、FINALとある。

src/headerssync.h, src/headerssync.cpp を見てみる。
### headerssync.h
A compressed CBlockHeader, which leaves out the prevhash
HeadersSyncState
We wish to download a peer’s headers chain in a DoS-resistant way.
* – In the first download phase, called pre-synchronization, we can calculate
* the work on the chain as we go (just by checking the nBits value on each
* header, and validating the proof-of-work).
In phase 1 (presync)
In phase 2 (redownload)

#### headerssync.cpp
// The two constants below are computed using the simulation script in
// contrib/devtools/headerssync-params.py.
m_max_commitments = 6*(Ticks(NodeClock::now() – NodeSeconds{std::chrono::seconds{chain_start->GetMedianTimePast()}}) + MAX_FUTURE_BLOCK_TIME) / HEADER_COMMITMENT_PERIOD;

downloadはこれでやってる?

    if (m_current_chain_work >= m_minimum_required_work) {
        m_redownloaded_headers.clear();
        m_redownload_buffer_last_height = m_chain_start->nHeight;
        m_redownload_buffer_first_prev_hash = m_chain_start->GetBlockHash();
        m_redownload_buffer_last_hash = m_chain_start->GetBlockHash();
        m_redownload_chain_work = m_chain_start->nChainWork;
        m_download_state = State::REDOWNLOAD;
        LogPrint(BCLog::NET, "Initial headers sync transition with peer=%d: reached sufficient work at height=%i, redownloading from height=%i\n", m_id, m_current_height, m_redownload_buffer_last_height);
    }

downloadのstatusに応じて処理しているのはわかるが、getHashの処理とかはheaderssync.cppの中には書いてないように見えるがどこでやってるんだろうか?

あと、基本的に、HeadersSyncState::${処理}と書かれていますね。
なんか凄いな…