从torrent文件中提取SHA1哈希

Question

我已经四处寻找答案,但我似乎只能找到适合你的软件.有人知道如何在python中这样做吗？

Answer 1

我写了一段python代码,它根据.torrent文件中的内容验证下载文件的哈希值.假设您要检查下载是否有损坏,您可能会觉得这很有用.

您需要bencode包才能使用它.Bencode是.torrent文件中使用的序列化格式.它可以像JSON一样封送列表,字典,字符串和数字.

代码获取info['pieces']字符串中包含的哈希值:

torrent_file = open(sys.argv[1], "rb")
metainfo = bencode.bdecode(torrent_file.read())
info = metainfo['info']
pieces = StringIO.StringIO(info['pieces'])

该字符串包含一系列20字节的哈希值(每个哈希值一个).然后将这些散列与磁盘文件的散列进行比较.

此代码中唯一复杂的部分是处理多文件种子,因为单个torrent 片段可以跨越多个文件(内部BitTorrent将多文件下载视为单个连续文件).我正在使用生成器函数pieces_generator()来抽象它.

您可能需要阅读BitTorrent规范以更详细地了解这一点.

全部代码如下:

import sys, os, hashlib, StringIO, bencode

def pieces_generator(info):
    """Yield pieces from download file(s)."""
    piece_length = info['piece length']
    if 'files' in info: # yield pieces from a multi-file torrent
        piece = ""
        for file_info in info['files']:
            path = os.sep.join([info['name']] + file_info['path'])
            print path
            sfile = open(path.decode('UTF-8'), "rb")
            while True:
                piece += sfile.read(piece_length-len(piece))
                if len(piece) != piece_length:
                    sfile.close()
                    break
                yield piece
                piece = ""
        if piece != "":
            yield piece
    else: # yield pieces from a single file torrent
        path = info['name']
        print path
        sfile = open(path.decode('UTF-8'), "rb")
        while True:
            piece = sfile.read(piece_length)
            if not piece:
                sfile.close()
                return
            yield piece

def corruption_failure():
    """Display error message and exit"""
    print("download corrupted")
    exit(1)

def main():
    # Open torrent file
    torrent_file = open(sys.argv[1], "rb")
    metainfo = bencode.bdecode(torrent_file.read())
    info = metainfo['info']
    pieces = StringIO.StringIO(info['pieces'])
    # Iterate through pieces
    for piece in pieces_generator(info):
        # Compare piece hash with expected hash
        piece_hash = hashlib.sha1(piece).digest()
        if (piece_hash != pieces.read(20)):
            corruption_failure()
    # ensure we've read all pieces 
    if pieces.read():
        corruption_failure()

if __name__ == "__main__":
    main()

Answer 2

我在这里如何从torrent文件中提取HASH值:

#!/usr/bin/python

import sys, os, hashlib, StringIO
import bencode



def main():
    # Open torrent file
    torrent_file = open(sys.argv[1], "rb")
    metainfo = bencode.bdecode(torrent_file.read())
    info = metainfo['info']
    print hashlib.sha1(bencode.bencode(info)).hexdigest()    

if __name__ == "__main__":
    main()

它与运行命令相同:

transmissioncli -i test.torrent 2>/dev/null | grep "^hash:" | awk '{print $2}'

希望能帮助到你 :)