Torrent 词汇

• metainfo - .torrent - application/x-bittorrent
• uTP - uTorrent Transport Protocol
  • bittorrent/libutp
• Leecher -> downloader
• Seeder
• Lurker
• bencode
• tracker
• DHT - distributed hash table
• swarm
• Tracker
  • 跟踪 seeds 和
  • DHT 使得 Tracker 不再必须 - 但 tracker 能提高发现速度
• Tracker Server
  • qBittorrent 内置
  • opentracker
  • Comparison of BitTorrent tracker software
• hash
  • sha1 160 bit hashes
• Glossary of BitTorrent terms

Piece / 片段

• 做种的文件会被划分为片段
• 通常为 64kB, 128kB, 512kB, 1MB, 2MB, 4MB, 8MB
• 片段一般会随机分发
• .torrent 文件包含了每个片段的 hash - MD4 - 20 byte
• .torrent 文件中定义的文件通过 offset 和 length 来查找所需的片段

ed2k

• 特殊的链接格式
• 常见
  • ed2k://|file|<file name>|<file size>|<file hash>|h=<Root Hash>|/
• RootHash 用于 AICH 算法参数
• eD2k Links

ICH - Intelligent Corruption Handling

• 基于 Hash Set
• Corruption Handling

AICH - Advanced Intelligent Corruption Handling

• 基于 Root Hash

下载器常见特性

• preload magnet metadata
• tracker exchange
• embedded tracker
• built-in search engine
• super-seeding
  • Super-seeding is an algorithm used to allow downloaders become uploaders quicker.
• broadcatching
  • automatically downloading content as soon as it's available
  • usually implemented via RSS
  • proxy server
• Prioritization, Selective Downloading, DHT, PEX, LPD, Magnet URI
• MSE/PE security
• UPnP, NAT-PMP, NAT traversal for automatic router configuration
• UDP tracker and µTP data transfer protocol
• Web seeding and Local Peer Discovery