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  2. Subject: BitTorrentSpecification - TheoryOrg

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  3. Date: Thu, 8 Sep 2011 06:20:06 +0800

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  128. <BODY class=3D"mediawiki ltr ns-0 ns-subject =

    129. 

  129. page-BitTorrentSpecification skin-monobook">

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  130. <DIV id=3D"globalWrapper">

    131. 

  131. <DIV id=3D"column-content">

    132. 

  132. <DIV id=3D"content"><A id=3D"top"></A>

    133. 

  133. <H1 id=3D"firstHeading" =

    134. 

  134. class=3D"firstHeading">BitTorrentSpecification</H1>

    135. 

  135. <DIV id=3D"bodyContent">

    136. 

  136. <H3 id=3D"siteSub">From TheoryOrg</H3>

    137. 

  137. <DIV id=3D"contentSub"></DIV>

    138. 

  138. <DIV id=3D"jump-to-nav">Jump to: <A =

    139. 

  139. href=3D"http://wiki.theory.org/BitTorrentSpecification#column-one">naviga=

    140. 

  140. tion</A>,=20

    141. 

  141. <A=20

    142. 

  142. href=3D"http://wiki.theory.org/BitTorrentSpecification#searchInput">searc=

    143. 

  143. h</A></DIV><!-- start content -->

    144. 

  144. <P><BIG><BIG><BIG> <I><B>Bittorrent Protocol Specification v1.0</B></I>=20

    145. 

  145. </BIG></BIG></BIG></P>

    146. 

  146. <TABLE id=3D"toc" class=3D"toc">

    147. 

  147.   <TBODY>

    148. 

  148.   <TR>

    149. 

  149.     <TD>

    150. 

  150.       <DIV id=3D"toctitle">

    151. 

  151.       <H2>Contents</H2></DIV>

    152. 

  152.       <UL>

    153. 

  153.         <LI class=3D"toclevel-1 tocsection-1"><A =

    154. 

  154. href=3D"http://wiki.theory.org/BitTorrentSpecification#Identification"><S=

    155. 

  155. PAN=20

    156. 

  156.         class=3D"tocnumber">1</SPAN> <SPAN=20

    157. 

  157.         class=3D"toctext">Identification</SPAN></A></LI>

    158. 

  158.         <LI class=3D"toclevel-1 tocsection-2"><A =

    159. 

  159. href=3D"http://wiki.theory.org/BitTorrentSpecification#Purpose"><SPAN=20

    160. 

  160.         class=3D"tocnumber">2</SPAN> <SPAN =

    161. 

  161. class=3D"toctext">Purpose</SPAN></A></LI>

    162. 

  162.         <LI class=3D"toclevel-1 tocsection-3"><A =

    163. 

  163. href=3D"http://wiki.theory.org/BitTorrentSpecification#Scope"><SPAN=20

    164. 

  164.         class=3D"tocnumber">3</SPAN> <SPAN =

    165. 

  165. class=3D"toctext">Scope</SPAN></A></LI>

    166. 

  166.         <LI class=3D"toclevel-1 tocsection-4"><A =

    167. 

  167. href=3D"http://wiki.theory.org/BitTorrentSpecification#Related_Documents"=

    168. 

  168. ><SPAN=20

    169. 

  169.         class=3D"tocnumber">4</SPAN> <SPAN class=3D"toctext">Related=20

    170. 

  170.         Documents</SPAN></A></LI>

    171. 

  171.         <LI class=3D"toclevel-1 tocsection-5"><A =

    172. 

  172. href=3D"http://wiki.theory.org/BitTorrentSpecification#Conventions"><SPAN=

    173. 

  173. =20

    174. 

  174.         class=3D"tocnumber">5</SPAN> <SPAN=20

    175. 

  175.         class=3D"toctext">Conventions</SPAN></A></LI>

    176. 

  176.         <LI class=3D"toclevel-1 tocsection-6"><A =

    177. 

  177. href=3D"http://wiki.theory.org/BitTorrentSpecification#Bencoding"><SPAN=20

    178. 

  178.         class=3D"tocnumber">6</SPAN> <SPAN =

    179. 

  179. class=3D"toctext">Bencoding</SPAN></A>

    180. 

  180.         <UL>

    181. 

  181.           <LI class=3D"toclevel-2 tocsection-7"><A =

    182. 

  182. href=3D"http://wiki.theory.org/BitTorrentSpecification#Bencoded_Strings">=

    183. 

  183. <SPAN=20

    184. 

  184.           class=3D"tocnumber">6.1</SPAN> <SPAN =

    185. 

  185. class=3D"toctext">Bencoded=20

    186. 

  186.           Strings</SPAN></A></LI>

    187. 

  187.           <LI class=3D"toclevel-2 tocsection-8"><A =

    188. 

  188. href=3D"http://wiki.theory.org/BitTorrentSpecification#Integers"><SPAN=20

    189. 

  189.           class=3D"tocnumber">6.2</SPAN> <SPAN=20

    190. 

  190.           class=3D"toctext">Integers</SPAN></A></LI>

    191. 

  191.           <LI class=3D"toclevel-2 tocsection-9"><A =

    192. 

  192. href=3D"http://wiki.theory.org/BitTorrentSpecification#Lists"><SPAN=20

    193. 

  193.           class=3D"tocnumber">6.3</SPAN> <SPAN=20

    194. 

  194.           class=3D"toctext">Lists</SPAN></A></LI>

    195. 

  195.           <LI class=3D"toclevel-2 tocsection-10"><A =

    196. 

  196. href=3D"http://wiki.theory.org/BitTorrentSpecification#Dictionaries"><SPA=

    197. 

  197. N=20

    198. 

  198.           class=3D"tocnumber">6.4</SPAN> <SPAN=20

    199. 

  199.           class=3D"toctext">Dictionaries</SPAN></A></LI>

    200. 

  200.           <LI class=3D"toclevel-2 tocsection-11"><A =

    201. 

  201. href=3D"http://wiki.theory.org/BitTorrentSpecification#Implementations"><=

    202. 

  202. SPAN=20

    203. 

  203.           class=3D"tocnumber">6.5</SPAN> <SPAN=20

    204. 

  204.           class=3D"toctext">Implementations</SPAN></A></LI></UL></LI>

    205. 

  205.         <LI class=3D"toclevel-1 tocsection-12"><A =

    206. 

  206. href=3D"http://wiki.theory.org/BitTorrentSpecification#Metainfo_File_Stru=

    207. 

  207. cture"><SPAN=20

    208. 

  208.         class=3D"tocnumber">7</SPAN> <SPAN class=3D"toctext">Metainfo =

    209. 

  209. File=20

    210. 

  210.         Structure</SPAN></A>

    211. 

  211.         <UL>

    212. 

  212.           <LI class=3D"toclevel-2 tocsection-13"><A =

    213. 

  213. href=3D"http://wiki.theory.org/BitTorrentSpecification#Info_Dictionary"><=

    214. 

  214. SPAN=20

    215. 

  215.           class=3D"tocnumber">7.1</SPAN> <SPAN class=3D"toctext">Info=20

    216. 

  216.           Dictionary</SPAN></A>

    217. 

  217.           <UL>

    218. 

  218.             <LI class=3D"toclevel-3 tocsection-14"><A =

    219. 

  219. href=3D"http://wiki.theory.org/BitTorrentSpecification#Info_in_Single_Fil=

    220. 

  220. e_Mode"><SPAN=20

    221. 

  221.             class=3D"tocnumber">7.1.1</SPAN> <SPAN =

    222. 

  222. class=3D"toctext">Info in Single=20

    223. 

  223.             File Mode</SPAN></A></LI>

    224. 

  224.             <LI class=3D"toclevel-3 tocsection-15"><A =

    225. 

  225. href=3D"http://wiki.theory.org/BitTorrentSpecification#Info_in_Multiple_F=

    226. 

  226. ile_Mode"><SPAN=20

    227. 

  227.             class=3D"tocnumber">7.1.2</SPAN> <SPAN =

    228. 

  228. class=3D"toctext">Info in=20

    229. 

  229.             Multiple File Mode</SPAN></A></LI></UL></LI>

    230. 

  230.           <LI class=3D"toclevel-2 tocsection-16"><A =

    231. 

  231. href=3D"http://wiki.theory.org/BitTorrentSpecification#Notes"><SPAN=20

    232. 

  232.           class=3D"tocnumber">7.2</SPAN> <SPAN=20

    233. 

  233.           class=3D"toctext">Notes</SPAN></A></LI></UL></LI>

    234. 

  234.         <LI class=3D"toclevel-1 tocsection-17"><A =

    235. 

  235. href=3D"http://wiki.theory.org/BitTorrentSpecification#Tracker_HTTP.2FHTT=

    236. 

  236. PS_Protocol"><SPAN=20

    237. 

  237.         class=3D"tocnumber">8</SPAN> <SPAN class=3D"toctext">Tracker =

    238. 

  238. HTTP/HTTPS=20

    239. 

  239.         Protocol</SPAN></A>

    240. 

  240.         <UL>

    241. 

  241.           <LI class=3D"toclevel-2 tocsection-18"><A =

    242. 

  242. href=3D"http://wiki.theory.org/BitTorrentSpecification#Tracker_Request_Pa=

    243. 

  243. rameters"><SPAN=20

    244. 

  244.           class=3D"tocnumber">8.1</SPAN> <SPAN class=3D"toctext">Tracker =

    245. 

  245. Request=20

    246. 

  246.           Parameters</SPAN></A></LI>

    247. 

  247.           <LI class=3D"toclevel-2 tocsection-19"><A =

    248. 

  248. href=3D"http://wiki.theory.org/BitTorrentSpecification#Tracker_Response">=

    249. 

  249. <SPAN=20

    250. 

  250.           class=3D"tocnumber">8.2</SPAN> <SPAN class=3D"toctext">Tracker =

    251. 

  251. 

    252. 

  252.           Response</SPAN></A></LI></UL></LI>

    253. 

  253.         <LI class=3D"toclevel-1 tocsection-20"><A =

    254. 

  254. href=3D"http://wiki.theory.org/BitTorrentSpecification#Tracker_.27scrape.=

    255. 

  255. 27_Convention"><SPAN=20

    256. 

  256.         class=3D"tocnumber">9</SPAN> <SPAN class=3D"toctext">Tracker =

    257. 

  257. 'scrape'=20

    258. 

  258.         Convention</SPAN></A>

    259. 

  259.         <UL>

    260. 

  260.           <LI class=3D"toclevel-2 tocsection-21"><A =

    261. 

  261. href=3D"http://wiki.theory.org/BitTorrentSpecification#Unofficial_extensi=

    262. 

  262. ons_to_scrape"><SPAN=20

    263. 

  263.           class=3D"tocnumber">9.1</SPAN> <SPAN =

    264. 

  264. class=3D"toctext">Unofficial=20

    265. 

  265.           extensions to scrape</SPAN></A></LI></UL></LI>

    266. 

  266.         <LI class=3D"toclevel-1 tocsection-22"><A =

    267. 

  267. href=3D"http://wiki.theory.org/BitTorrentSpecification#Peer_wire_protocol=

    268. 

  268. _.28TCP.29"><SPAN=20

    269. 

  269.         class=3D"tocnumber">10</SPAN> <SPAN class=3D"toctext">Peer wire =

    270. 

  270. protocol=20

    271. 

  271.         (TCP)</SPAN></A>

    272. 

  272.         <UL>

    273. 

  273.           <LI class=3D"toclevel-2 tocsection-23"><A =

    274. 

  274. href=3D"http://wiki.theory.org/BitTorrentSpecification#Overview"><SPAN=20

    275. 

  275.           class=3D"tocnumber">10.1</SPAN> <SPAN=20

    276. 

  276.           class=3D"toctext">Overview</SPAN></A></LI>

    277. 

  277.           <LI class=3D"toclevel-2 tocsection-24"><A =

    278. 

  278. href=3D"http://wiki.theory.org/BitTorrentSpecification#Data_Types"><SPAN =

    279. 

  279. 

    280. 

  280.           class=3D"tocnumber">10.2</SPAN> <SPAN class=3D"toctext">Data=20

    281. 

  281.           Types</SPAN></A></LI>

    282. 

  282.           <LI class=3D"toclevel-2 tocsection-25"><A =

    283. 

  283. href=3D"http://wiki.theory.org/BitTorrentSpecification#Message_flow"><SPA=

    284. 

  284. N=20

    285. 

  285.           class=3D"tocnumber">10.3</SPAN> <SPAN =

    286. 

  286. class=3D"toctext">Message=20

    287. 

  287.           flow</SPAN></A></LI>

    288. 

  288.           <LI class=3D"toclevel-2 tocsection-26"><A =

    289. 

  289. href=3D"http://wiki.theory.org/BitTorrentSpecification#Handshake"><SPAN=20

    290. 

  290.           class=3D"tocnumber">10.4</SPAN> <SPAN=20

    291. 

  291.           class=3D"toctext">Handshake</SPAN></A>

    292. 

  292.           <UL>

    293. 

  293.             <LI class=3D"toclevel-3 tocsection-27"><A =

    294. 

  294. href=3D"http://wiki.theory.org/BitTorrentSpecification#peer_id"><SPAN=20

    295. 

  295.             class=3D"tocnumber">10.4.1</SPAN> <SPAN=20

    296. 

  296.             class=3D"toctext">peer_id</SPAN></A></LI></UL></LI>

    297. 

  297.           <LI class=3D"toclevel-2 tocsection-28"><A =

    298. 

  298. href=3D"http://wiki.theory.org/BitTorrentSpecification#Messages"><SPAN=20

    299. 

  299.           class=3D"tocnumber">10.5</SPAN> <SPAN=20

    300. 

  300.           class=3D"toctext">Messages</SPAN></A>

    301. 

  301.           <UL>

    302. 

  302.             <LI class=3D"toclevel-3 tocsection-29"><A =

    303. 

  303. href=3D"http://wiki.theory.org/BitTorrentSpecification#keep-alive:_.3Clen=

    304. 

  304. .3D0000.3E"><SPAN=20

    305. 

  305.             class=3D"tocnumber">10.5.1</SPAN> <SPAN =

    306. 

  306. class=3D"toctext">keep-alive:=20

    307. 

  307.             &lt;len=3D0000&gt;</SPAN></A></LI>

    308. 

  308.             <LI class=3D"toclevel-3 tocsection-30"><A =

    309. 

  309. href=3D"http://wiki.theory.org/BitTorrentSpecification#choke:_.3Clen.3D00=

    310. 

  310. 01.3E.3Cid.3D0.3E"><SPAN=20

    311. 

  311.             class=3D"tocnumber">10.5.2</SPAN> <SPAN =

    312. 

  312. class=3D"toctext">choke:=20

    313. 

  313.             &lt;len=3D0001&gt;&lt;id=3D0&gt;</SPAN></A></LI>

    314. 

  314.             <LI class=3D"toclevel-3 tocsection-31"><A =

    315. 

  315. href=3D"http://wiki.theory.org/BitTorrentSpecification#unchoke:_.3Clen.3D=

    316. 

  316. 0001.3E.3Cid.3D1.3E"><SPAN=20

    317. 

  317.             class=3D"tocnumber">10.5.3</SPAN> <SPAN =

    318. 

  318. class=3D"toctext">unchoke:=20

    319. 

  319.             &lt;len=3D0001&gt;&lt;id=3D1&gt;</SPAN></A></LI>

    320. 

  320.             <LI class=3D"toclevel-3 tocsection-32"><A =

    321. 

  321. href=3D"http://wiki.theory.org/BitTorrentSpecification#interested:_.3Clen=

    322. 

  322. .3D0001.3E.3Cid.3D2.3E"><SPAN=20

    323. 

  323.             class=3D"tocnumber">10.5.4</SPAN> <SPAN =

    324. 

  324. class=3D"toctext">interested:=20

    325. 

  325.             &lt;len=3D0001&gt;&lt;id=3D2&gt;</SPAN></A></LI>

    326. 

  326.             <LI class=3D"toclevel-3 tocsection-33"><A =

    327. 

  327. href=3D"http://wiki.theory.org/BitTorrentSpecification#not_interested:_.3=

    328. 

  328. Clen.3D0001.3E.3Cid.3D3.3E"><SPAN=20

    329. 

  329.             class=3D"tocnumber">10.5.5</SPAN> <SPAN =

    330. 

  330. class=3D"toctext">not=20

    331. 

  331.             interested: &lt;len=3D0001&gt;&lt;id=3D3&gt;</SPAN></A></LI>

    332. 

  332.             <LI class=3D"toclevel-3 tocsection-34"><A =

    333. 

  333. href=3D"http://wiki.theory.org/BitTorrentSpecification#have:_.3Clen.3D000=

    334. 

  334. 5.3E.3Cid.3D4.3E.3Cpiece_index.3E"><SPAN=20

    335. 

  335.             class=3D"tocnumber">10.5.6</SPAN> <SPAN =

    336. 

  336. class=3D"toctext">have:=20

    337. 

  337.             &lt;len=3D0005&gt;&lt;id=3D4&gt;&lt;piece =

    338. 

  338. index&gt;</SPAN></A></LI>

    339. 

  339.             <LI class=3D"toclevel-3 tocsection-35"><A =

    340. 

  340. href=3D"http://wiki.theory.org/BitTorrentSpecification#bitfield:_.3Clen.3=

    341. 

  341. D0001.2BX.3E.3Cid.3D5.3E.3Cbitfield.3E"><SPAN=20

    342. 

  342.             class=3D"tocnumber">10.5.7</SPAN> <SPAN =

    343. 

  343. class=3D"toctext">bitfield:=20

    344. 

  344.             =

    345. 

  345. &lt;len=3D0001+X&gt;&lt;id=3D5&gt;&lt;bitfield&gt;</SPAN></A></LI>

    346. 

  346.             <LI class=3D"toclevel-3 tocsection-36"><A =

    347. 

  347. href=3D"http://wiki.theory.org/BitTorrentSpecification#request:_.3Clen.3D=

    348. 

  348. 0013.3E.3Cid.3D6.3E.3Cindex.3E.3Cbegin.3E.3Clength.3E"><SPAN=20

    349. 

  349.             class=3D"tocnumber">10.5.8</SPAN> <SPAN =

    350. 

  350. class=3D"toctext">request:=20

    351. 

  351.             =

    352. 

  352. &lt;len=3D0013&gt;&lt;id=3D6&gt;&lt;index&gt;&lt;begin&gt;&lt;length&gt;<=

    353. 

  353. /SPAN></A></LI>

    354. 

  354.             <LI class=3D"toclevel-3 tocsection-37"><A =

    355. 

  355. href=3D"http://wiki.theory.org/BitTorrentSpecification#piece:_.3Clen.3D00=

    356. 

  356. 09.2BX.3E.3Cid.3D7.3E.3Cindex.3E.3Cbegin.3E.3Cblock.3E"><SPAN=20

    357. 

  357.             class=3D"tocnumber">10.5.9</SPAN> <SPAN =

    358. 

  358. class=3D"toctext">piece:=20

    359. 

  359.             =

    360. 

  360. &lt;len=3D0009+X&gt;&lt;id=3D7&gt;&lt;index&gt;&lt;begin&gt;&lt;block&gt;=

    361. 

  361. </SPAN></A></LI>

    362. 

  362.             <LI class=3D"toclevel-3 tocsection-38"><A =

    363. 

  363. href=3D"http://wiki.theory.org/BitTorrentSpecification#cancel:_.3Clen.3D0=

    364. 

  364. 013.3E.3Cid.3D8.3E.3Cindex.3E.3Cbegin.3E.3Clength.3E"><SPAN=20

    365. 

  365.             class=3D"tocnumber">10.5.10</SPAN> <SPAN =

    366. 

  366. class=3D"toctext">cancel:=20

    367. 

  367.             =

    368. 

  368. &lt;len=3D0013&gt;&lt;id=3D8&gt;&lt;index&gt;&lt;begin&gt;&lt;length&gt;<=

    369. 

  369. /SPAN></A></LI>

    370. 

  370.             <LI class=3D"toclevel-3 tocsection-39"><A =

    371. 

  371. href=3D"http://wiki.theory.org/BitTorrentSpecification#port:_.3Clen.3D000=

    372. 

  372. 3.3E.3Cid.3D9.3E.3Clisten-port.3E"><SPAN=20

    373. 

  373.             class=3D"tocnumber">10.5.11</SPAN> <SPAN =

    374. 

  374. class=3D"toctext">port:=20

    375. 

  375.             =

    376. 

  376. &lt;len=3D0003&gt;&lt;id=3D9&gt;&lt;listen-port&gt;</SPAN></A></LI></UL>

    377. 

  377.           </LI></UL></LI>

    378. 

  378.         <LI class=3D"toclevel-1 tocsection-40"><A =

    379. 

  379. href=3D"http://wiki.theory.org/BitTorrentSpecification#Algorithms"><SPAN =

    380. 

  380. 

    381. 

  381.         class=3D"tocnumber">11</SPAN> <SPAN =

    382. 

  382. class=3D"toctext">Algorithms</SPAN></A>

    383. 

  383.         <UL>

    384. 

  384.           <LI class=3D"toclevel-2 tocsection-41"><A =

    385. 

  385. href=3D"http://wiki.theory.org/BitTorrentSpecification#Queuing"><SPAN=20

    386. 

  386.           class=3D"tocnumber">11.1</SPAN> <SPAN=20

    387. 

  387.           class=3D"toctext">Queuing</SPAN></A></LI>

    388. 

  388.           <LI class=3D"toclevel-2 tocsection-42"><A =

    389. 

  389. href=3D"http://wiki.theory.org/BitTorrentSpecification#Super_Seeding"><SP=

    390. 

  390. AN=20

    391. 

  391.           class=3D"tocnumber">11.2</SPAN> <SPAN class=3D"toctext">Super=20

    392. 

  392.           Seeding</SPAN></A></LI>

    393. 

  393.           <LI class=3D"toclevel-2 tocsection-43"><A =

    394. 

  394. href=3D"http://wiki.theory.org/BitTorrentSpecification#Piece_downloading_=

    395. 

  395. strategy"><SPAN=20

    396. 

  396.           class=3D"tocnumber">11.3</SPAN> <SPAN class=3D"toctext">Piece =

    397. 

  397. downloading=20

    398. 

  398.           strategy</SPAN></A></LI>

    399. 

  399.           <LI class=3D"toclevel-2 tocsection-44"><A =

    400. 

  400. href=3D"http://wiki.theory.org/BitTorrentSpecification#End_Game"><SPAN=20

    401. 

  401.           class=3D"tocnumber">11.4</SPAN> <SPAN class=3D"toctext">End=20

    402. 

  402.           Game</SPAN></A></LI>

    403. 

  403.           <LI class=3D"toclevel-2 tocsection-45"><A =

    404. 

  404. href=3D"http://wiki.theory.org/BitTorrentSpecification#Choking_and_Optimi=

    405. 

  405. stic_Unchoking"><SPAN=20

    406. 

  406.           class=3D"tocnumber">11.5</SPAN> <SPAN =

    407. 

  407. class=3D"toctext">Choking and=20

    408. 

  408.           Optimistic Unchoking</SPAN></A>

    409. 

  409.           <UL>

    410. 

  410.             <LI class=3D"toclevel-3 tocsection-46"><A =

    411. 

  411. href=3D"http://wiki.theory.org/BitTorrentSpecification#Anti-snubbing"><SP=

    412. 

  412. AN=20

    413. 

  413.             class=3D"tocnumber">11.5.1</SPAN> <SPAN=20

    414. 

  414.             =

    415. 

  415. class=3D"toctext">Anti-snubbing</SPAN></A></LI></UL></LI></UL></LI>

    416. 

  416.         <LI class=3D"toclevel-1 tocsection-47"><A =

    417. 

  417. href=3D"http://wiki.theory.org/BitTorrentSpecification#Official_Extension=

    418. 

  418. s_To_The_Protocol"><SPAN=20

    419. 

  419.         class=3D"tocnumber">12</SPAN> <SPAN class=3D"toctext">Official =

    420. 

  420. Extensions To=20

    421. 

  421.         The Protocol</SPAN></A>

    422. 

  422.         <UL>

    423. 

  423.           <LI class=3D"toclevel-2 tocsection-48"><A =

    424. 

  424. href=3D"http://wiki.theory.org/BitTorrentSpecification#Fast_Peers_Extensi=

    425. 

  425. ons"><SPAN=20

    426. 

  426.           class=3D"tocnumber">12.1</SPAN> <SPAN class=3D"toctext">Fast =

    427. 

  427. Peers=20

    428. 

  428.           Extensions</SPAN></A></LI>

    429. 

  429.           <LI class=3D"toclevel-2 tocsection-49"><A =

    430. 

  430. href=3D"http://wiki.theory.org/BitTorrentSpecification#Distributed_Hash_T=

    431. 

  431. able"><SPAN=20

    432. 

  432.           class=3D"tocnumber">12.2</SPAN> <SPAN =

    433. 

  433. class=3D"toctext">Distributed Hash=20

    434. 

  434.           Table</SPAN></A></LI>

    435. 

  435.           <LI class=3D"toclevel-2 tocsection-50"><A =

    436. 

  436. href=3D"http://wiki.theory.org/BitTorrentSpecification#Connection_Obfusca=

    437. 

  437. tion"><SPAN=20

    438. 

  438.           class=3D"tocnumber">12.3</SPAN> <SPAN =

    439. 

  439. class=3D"toctext">Connection=20

    440. 

  440.           Obfuscation</SPAN></A></LI></UL></LI>

    441. 

  441.         <LI class=3D"toclevel-1 tocsection-51"><A =

    442. 

  442. href=3D"http://wiki.theory.org/BitTorrentSpecification#Unofficial_Extensi=

    443. 

  443. ons_To_The_Protocol"><SPAN=20

    444. 

  444.         class=3D"tocnumber">13</SPAN> <SPAN class=3D"toctext">Unofficial =

    445. 

  445. Extensions=20

    446. 

  446.         To The Protocol</SPAN></A>

    447. 

  447.         <UL>

    448. 

  448.           <LI class=3D"toclevel-2 tocsection-52"><A =

    449. 

  449. href=3D"http://wiki.theory.org/BitTorrentSpecification#Azureus_Messaging_=

    450. 

  450. Protocol"><SPAN=20

    451. 

  451.           class=3D"tocnumber">13.1</SPAN> <SPAN =

    452. 

  452. class=3D"toctext">Azureus Messaging=20

    453. 

  453.           Protocol</SPAN></A></LI>

    454. 

  454.           <LI class=3D"toclevel-2 tocsection-53"><A =

    455. 

  455. href=3D"http://wiki.theory.org/BitTorrentSpecification#WebSeeding"><SPAN =

    456. 

  456. 

    457. 

  457.           class=3D"tocnumber">13.2</SPAN> <SPAN=20

    458. 

  458.           class=3D"toctext">WebSeeding</SPAN></A></LI>

    459. 

  459.           <LI class=3D"toclevel-2 tocsection-54"><A =

    460. 

  460. href=3D"http://wiki.theory.org/BitTorrentSpecification#Extension_protocol=

    461. 

  461. "><SPAN=20

    462. 

  462.           class=3D"tocnumber">13.3</SPAN> <SPAN =

    463. 

  463. class=3D"toctext">Extension=20

    464. 

  464.           protocol</SPAN></A></LI>

    465. 

  465.           <LI class=3D"toclevel-2 tocsection-55"><A =

    466. 

  466. href=3D"http://wiki.theory.org/BitTorrentSpecification#Extension_Negotiat=

    467. 

  467. ion_Protocol"><SPAN=20

    468. 

  468.           class=3D"tocnumber">13.4</SPAN> <SPAN =

    469. 

  469. class=3D"toctext">Extension=20

    470. 

  470.           Negotiation Protocol</SPAN></A></LI>

    471. 

  471.           <LI class=3D"toclevel-2 tocsection-56"><A =

    472. 

  472. href=3D"http://wiki.theory.org/BitTorrentSpecification#BitTorrent_Locatio=

    473. 

  473. n-aware_Protocol_1.0"><SPAN=20

    474. 

  474.           class=3D"tocnumber">13.5</SPAN> <SPAN =

    475. 

  475. class=3D"toctext">BitTorrent=20

    476. 

  476.           Location-aware Protocol 1.0</SPAN></A></LI>

    477. 

  477.           <LI class=3D"toclevel-2 tocsection-57"><A =

    478. 

  478. href=3D"http://wiki.theory.org/BitTorrentSpecification#SimpleBT_Extension=

    479. 

  479. _Protocol"><SPAN=20

    480. 

  480.           class=3D"tocnumber">13.6</SPAN> <SPAN =

    481. 

  481. class=3D"toctext">SimpleBT Extension=20

    482. 

  482.           Protocol</SPAN></A></LI>

    483. 

  483.           <LI class=3D"toclevel-2 tocsection-58"><A =

    484. 

  484. href=3D"http://wiki.theory.org/BitTorrentSpecification#BitComet_Extension=

    485. 

  485. _Protocol"><SPAN=20

    486. 

  486.           class=3D"tocnumber">13.7</SPAN> <SPAN =

    487. 

  487. class=3D"toctext">BitComet Extension=20

    488. 

  488.           Protocol</SPAN></A></LI></UL></LI>

    489. 

  489.         <LI class=3D"toclevel-1 tocsection-59"><A =

    490. 

  490. href=3D"http://wiki.theory.org/BitTorrentSpecification#Reserved_Bytes"><S=

    491. 

  491. PAN=20

    492. 

  492.         class=3D"tocnumber">14</SPAN> <SPAN class=3D"toctext">Reserved=20

    493. 

  493.         Bytes</SPAN></A></LI>

    494. 

  494.         <LI class=3D"toclevel-1 tocsection-60"><A =

    495. 

  495. href=3D"http://wiki.theory.org/BitTorrentSpecification#Change_Log"><SPAN =

    496. 

  496. 

    497. 

  497.         class=3D"tocnumber">15</SPAN> <SPAN class=3D"toctext">Change=20

    498. 

  498.         Log</SPAN></A></LI>

    499. 

  499.         <LI class=3D"toclevel-1 tocsection-61"><A =

    500. 

  500. href=3D"http://wiki.theory.org/BitTorrentSpecification#Related_Links"><SP=

    501. 

  501. AN=20

    502. 

  502.         class=3D"tocnumber">16</SPAN> <SPAN class=3D"toctext">Related=20

    503. 

  503.         Links</SPAN></A></LI></UL></TD></TR></TBODY></TABLE>

    504. 

  504. <SCRIPT>if (window.showTocToggle) { var tocShowText =3D "show"; var =

    505. 

  505. tocHideText =3D "hide"; showTocToggle(); } </SCRIPT>

    506. 

  506. 

    507. 

  507. <H2> <SPAN id=3D"Identification" class=3D"mw-headline"> Identification =

    508. 

  508. </SPAN></H2>

    509. 

  509. <P><A class=3D"new" title=3D"BitTorrent (page does not exist)" =

    510. 

  510. href=3D"http://wiki.theory.org/index.php?title=3DBitTorrent&amp;action=3D=

    511. 

  511. edit&amp;redlink=3D1">BitTorrent</A>=20

    512. 

  512. is a peer-to-peer file sharing protocol designed by Bram Cohen.  Visit =

    513. 

  513. his pages=20

    514. 

  514. at <A class=3D"external free" href=3D"http://www.bittorrent.com/"=20

    515. 

  515. rel=3D"nofollow">http://www.bittorrent.com/</A> BitTorrent is designed =

    516. 

  516. to=20

    517. 

  517. facilitate file transfers among multiple peers across unreliable =

    518. 

  518. networks.</P>

    519. 

  519. <H2> <SPAN id=3D"Purpose" class=3D"mw-headline"> Purpose </SPAN></H2>

    520. 

  520. <P>The purpose of this specification is to document version 1.0 of the=20

    521. 

  521. BitTorrent protocol specification in detail.  Bram's  <A =

    522. 

  522. class=3D"external text"=20

    523. 

  523. href=3D"http://bittorrent.org/beps/bep_0003.html" =

    524. 

  524. rel=3D"nofollow">protocol=20

    525. 

  525. specification page</A> outlines the protocol in somewhat general terms, =

    526. 

  526. and=20

    527. 

  527. lacks behaviorial detail in some areas.  The hope is that this document =

    528. 

  528. will=20

    529. 

  529. become a <B>formal</B> specification, written in clear, unambiguous =

    530. 

  530. terms, which=20

    531. 

  531. can be used as a basis for discussion and implementation in the =

    532. 

  532. future.</P>

    533. 

  533. <P>This document is intended to be maintained and used by the BitTorrent =

    534. 

  534. 

    535. 

  535. development community.  Everyone is invited to contribute to this =

    536. 

  536. document, with=20

    537. 

  537. the understanding that the content here is intended to represent the =

    538. 

  538. current=20

    539. 

  539. protocol (What if the current protocol is 2.0? The scope is then =

    540. 

  540. conflicting),=20

    541. 

  541. which is already deployed in a number of existing client =

    542. 

  542. implementations.</P>

    543. 

  543. <P>This is not the place to suggest feature requests.  For that, please =

    544. 

  544. go to=20

    545. 

  545. the <A class=3D"external text" =

    546. 

  546. href=3D"http://lists.ibiblio.org/mailman/listinfo/bittorrent"=20

    547. 

  547. rel=3D"nofollow">mailing list</A>.</P>

    548. 

  548. <H2> <SPAN id=3D"Scope" class=3D"mw-headline"> Scope </SPAN></H2>

    549. 

  549. <P>This document applies to the first version (i.e. version 1.0) of the=20

    550. 

  550. BitTorrent protocol specification. Currently, this applies to the =

    551. 

  551. torrent file=20

    552. 

  552. structure, peer wire protocol, and the Tracker HTTP/HTTPS protocol=20

    553. 

  553. specifications. As newer revisions of each protocol are defined, they =

    554. 

  554. should be=20

    555. 

  555. specified on their own separate pages, <B>not here</B>.</P>

    556. 

  556. <H2> <SPAN id=3D"Related_Documents" class=3D"mw-headline"> Related =

    557. 

  557. Documents=20

    558. 

  558. </SPAN></H2>

    559. 

  559. <UL>

    560. 

  560.   <LI> <A class=3D"external text" =

    561. 

  561. href=3D"http://bittorrent.org/beps/bep_0003.html"=20

    562. 

  562.   rel=3D"nofollow">Official protocol specification</A></LI>

    563. 

  563.   <LI> <A title=3D"BitTorrentWishList" =

    564. 

  564. href=3D"http://wiki.theory.org/BitTorrentWishList">Developer=20

    565. 

  565.   and user wishlist</A></LI>

    566. 

  566.   <LI> <A title=3D"BitTorrentTrackerExtensions" =

    567. 

  567. href=3D"http://wiki.theory.org/BitTorrentTrackerExtensions">Tracker=20

    568. 

  568.   protocol extensions</A></LI></UL>

    569. 

  569. <H2> <SPAN id=3D"Conventions" class=3D"mw-headline"> Conventions =

    570. 

  570. </SPAN></H2>

    571. 

  571. <P>In this document, a number of conventions are used in an attempt to =

    572. 

  572. present=20

    573. 

  573. information in a concise and unambiguous fashion.</P>

    574. 

  574. <UL>

    575. 

  575.   <LI> <I>peer</I> v/s <I>client</I>: In this document, a <I>peer</I> is =

    576. 

  576. any=20

    577. 

  577.   BitTorrent client participating in a download.  The <I>client</I> is =

    578. 

  578. also a=20

    579. 

  579.   peer, however it is the BitTorrent client that is running on the local =

    580. 

  580. 

    581. 

  581.   machine.  Readers of this specification may choose to think of =

    582. 

  582. themselves as=20

    583. 

  583.   the <I>client</I> which connects to numerous <I>peers</I>.</LI>

    584. 

  584.   <LI> <I>piece</I> v/s <I>block</I>: In this document, a <I>piece</I> =

    585. 

  585. refers to=20

    586. 

  586.   a portion of the downloaded data that is described in the metainfo =

    587. 

  587. file, which=20

    588. 

  588.   can be verified by a SHA1 hash.  A <I>block</I> is a portion of data =

    589. 

  589. that a=20

    590. 

  590.   <I>client</I> may request from at least one <I>peer</I>.  Two or more=20

    591. 

  591.   <I>blocks</I> make up a whole <I>piece</I>, which may then be =

    592. 

  592. verified.</LI>

    593. 

  593.   <LI> <I>defacto standard</I>: Large blocks of text in <I>italics</I> =

    594. 

  594. indicates=20

    595. 

  595.   a practice so common in various client implementations of BitTorrent =

    596. 

  596. that it=20

    597. 

  597.   is considered a defacto standard.</LI></UL>

    598. 

  598. <P>In order to help others find recent changes that have been made to =

    599. 

  599. this=20

    600. 

  600. document, please fill out the change log (last section).  This should =

    601. 

  601. contain a=20

    602. 

  602. brief (i.e. one-line) entry for each major change that you've made to =

    603. 

  603. the=20

    604. 

  604. document.</P>

    605. 

  605. <H2> <SPAN id=3D"Bencoding" class=3D"mw-headline"> Bencoding =

    606. 

  606. </SPAN></H2>

    607. 

  607. <P>Bencoding is a way to specify and organize data in a terse format.  =

    608. 

  608. It=20

    609. 

  609. supports the following types: byte strings, integers, lists, and =

    610. 

  610. dictionaries.

    611. 

  611. </P>

    612. 

  612. <H3> <SPAN id=3D"Bencoded_Strings" class=3D"mw-headline"> Bencoded =

    613. 

  613. Strings=20

    614. 

  614. </SPAN></H3>

    615. 

  615. <P>Bencoded strings are encoded as follows: <I>&lt;string length encoded =

    616. 

  616. in base=20

    617. 

  617. ten ASCII&gt;<B>:</B>&lt;string data&gt;</I>, or =

    618. 

  618. <I>key</I>:<I>value</I><BR>Note=20

    619. 

  619. that there is no constant beginning delimiter, and no ending =

    620. 

  620. delimiter.</P>

    621. 

  621. <DL>

    622. 

  622.   <DD><B>Example</B>: <I>4<B>:</B>spam</I> represents the string =

    623. 

  623. "spam"</DD></DL>

    624. 

  624. <H3> <SPAN id=3D"Integers" class=3D"mw-headline"> Integers </SPAN></H3>

    625. 

  625. <P>Integers are encoded as follows: <I><B>i</B>&lt;integer encoded in =

    626. 

  626. base ten=20

    627. 

  627. ASCII&gt;<B>e</B></I><BR>The initial <B>i</B> and trailing <B>e</B> are=20

    628. 

  628. beginning and ending delimiters. You can have negative numbers such as=20

    629. 

  629. <I><B>i</B>-3<B>e</B></I>. Only the significant digits should be used, =

    630. 

  630. one=20

    631. 

  631. cannot pad the Integer with zeroes. such as <I><B>i</B>04<B>e</B></I>.  =

    632. 

  632. However,=20

    633. 

  633. <I><B>i</B>0<B>e</B></I> is valid.</P>

    634. 

  634. <DL>

    635. 

  635.   <DD><B>Example</B>: <I><B>i</B>3<B>e</B></I> represents the integer =

    636. 

  636. "3"

    637. 

  637. </DD></DL>

    638. 

  638. <UL>

    639. 

  639.   <LI> <I>NOTE:</I> The maximum number of bit of this integer is =

    640. 

  640. unspecified,=20

    641. 

  641.   but to handle it as a signed 64bit integer is mandatory to handle =

    642. 

  642. "large=20

    643. 

  643.   files" aka .torrent for more that 4Gbyte.</LI></UL>

    644. 

  644. <H3> <SPAN id=3D"Lists" class=3D"mw-headline"> Lists </SPAN></H3>

    645. 

  645. <P>Lists are encoded as follows: <I><B>l</B>&lt;bencoded=20

    646. 

  646. values&gt;<B>e</B></I><BR>The initial <B>l</B> and trailing <B>e</B> are =

    647. 

  647. 

    648. 

  648. beginning and ending delimiters. Lists may contain any bencoded type, =

    649. 

  649. including=20

    650. 

  650. integers, strings, dictionaries, and even lists within other lists.</P>

    651. 

  651. <DL>

    652. 

  652.   <DD><B>Example:</B> <I><B>l</B>4:spam4:eggs<B>e</B></I> represents the =

    653. 

  653. list of=20

    654. 

  654.   two strings: [ "spam", "eggs" ]</DD></DL>

    655. 

  655. <H3> <SPAN id=3D"Dictionaries" class=3D"mw-headline"> Dictionaries =

    656. 

  656. </SPAN></H3>

    657. 

  657. <P>Dictionaries are encoded as follows: <I><B>d</B>&lt;bencoded=20

    658. 

  658. string&gt;&lt;bencoded element&gt;<B>e</B></I> <BR>The initial <B>d</B> =

    659. 

  659. and=20

    660. 

  660. trailing <B>e</B> are the beginning and ending delimiters. Note that the =

    661. 

  661. keys=20

    662. 

  662. must be bencoded strings.  The values may be any bencoded type, =

    663. 

  663. including=20

    664. 

  664. integers, strings, lists, and other dictionaries.  Keys must be strings =

    665. 

  665. and=20

    666. 

  666. appear in sorted order (sorted as raw strings, not alphanumerics). The =

    667. 

  667. strings=20

    668. 

  668. should be compared using a binary  comparison, not a culture-specific =

    669. 

  669. "natural"=20

    670. 

  670. comparison.</P>

    671. 

  671. <DL>

    672. 

  672.   <DD><B>Example</B>: <I><B>d</B>3:cow3:moo4:spam4:eggs<B>e</B> =

    673. 

  673. represents the=20

    674. 

  674.   dictionary { "cow" =3D&gt; "moo", "spam" =3D&gt; "eggs" } =

    675. 

  675. <BR></I></DD>

    676. 

  676.   <DD><B>Example</B>: <I><B>d</B>4:spaml1:a1:b<B>ee'</B> represents the=20

    677. 

  677.   dictionary { "spam" =3D&gt; [ "a", "b" ] } <BR></I></DD>

    678. 

  678.   <DD><B>Example</B>:=20

    679. 

  679.   =

    680. 

  680. <I><B>d</B>9:publisher3:bob17:publisher-webpage15:www.example.com18:publi=

    681. 

  681. sher.location4:home<B>e</B></I>=20

    682. 

  682.   represents { "publisher" =3D&gt; "bob", "publisher-webpage" =3D&gt;=20

    683. 

  683.   "www.example.com", "publisher.location" =3D&gt; "home" }</DD></DL>

    684. 

  684. <H3> <SPAN id=3D"Implementations" class=3D"mw-headline"> Implementations =

    685. 

  685. 

    686. 

  686. </SPAN></H3>

    687. 

  687. <UL>

    688. 

  688.   <LI> <A class=3D"external text" =

    689. 

  689. href=3D"http://funzix.git.sourceforge.net/git/gitweb.cgi?p=3Dfunzix/funzi=

    690. 

  690. x;a=3Dblob;f=3Dbencode/bencode.c"=20

    691. 

  691.   rel=3D"nofollow">C</A> by <A class=3D"new" title=3D"User:Vapier (page =

    692. 

  692. does not exist)"=20

    693. 

  693.   =

    694. 

  694. href=3D"http://wiki.theory.org/index.php?title=3DUser:Vapier&amp;action=3D=

    695. 

  695. edit&amp;redlink=3D1">Mike=20

    696. 

  696.   Frysinger</A></LI>

    697. 

  697.   <LI> <A class=3D"external text" =

    698. 

  698. href=3D"http://search.cpan.org/dist/Convert-Bencode/lib/Convert/Bencode.p=

    699. 

  699. m"=20

    700. 

  700.   rel=3D"nofollow">Perl</A></LI>

    701. 

  701.   <LI> <A class=3D"external text" =

    702. 

  702. href=3D"http://www.koders.com/java/fid47111A56F2466C232E09AEF75A39915EC70=

    703. 

  703. D3536.aspx#L52"=20

    704. 

  704.   rel=3D"nofollow">Java</A></LI>

    705. 

  705.   <LI> <A title=3D"Decoding bencoded data with python" =

    706. 

  706. href=3D"http://wiki.theory.org/Decoding_bencoded_data_with_python">Python=

    707. 

  707. </A>=20

    708. 

  708.   by <A class=3D"new" title=3D"User:Hackeron (page does not exist)" =

    709. 

  709. href=3D"http://wiki.theory.org/index.php?title=3DUser:Hackeron&amp;action=

    710. 

  710. =3Dedit&amp;redlink=3D1">Hackeron</A>

    711. 

  711.   </LI>

    712. 

  712.   <LI> <A title=3D"Decoding encoding bencoded data with haskell" =

    713. 

  713. href=3D"http://wiki.theory.org/Decoding_encoding_bencoded_data_with_haske=

    714. 

  714. ll">Decoding=20

    715. 

  715.   encoding bencoded data with haskell</A> by <A class=3D"new" =

    716. 

  716. title=3D"User:Edi (page does not exist)"=20

    717. 

  717.   =

    718. 

  718. href=3D"http://wiki.theory.org/index.php?title=3DUser:Edi&amp;action=3Ded=

    719. 

  719. it&amp;redlink=3D1">Edi</A>

    720. 

  720.   </LI>

    721. 

  721.   <LI> <A class=3D"external text" =

    722. 

  722. href=3D"http://www.stupendous.net/projects/bencoding-obj-c-class/"=20

    723. 

  723.   rel=3D"nofollow">Objective-C</A> by <A class=3D"new" =

    724. 

  724. title=3D"User:Chrome (page does not exist)"=20

    725. 

  725.   =

    726. 

  726. href=3D"http://wiki.theory.org/index.php?title=3DUser:Chrome&amp;action=3D=

    727. 

  727. edit&amp;redlink=3D1">Chrome</A>

    728. 

  728.   </LI>

    729. 

  729.   <LI> <A title=3D"JScript: Converting a torrent file to a JScript =

    730. 

  730. dictionary"=20

    731. 

  731.   =

    732. 

  732. href=3D"http://wiki.theory.org/JScript:_Converting_a_torrent_file_to_a_JS=

    733. 

  733. cript_dictionary">JScript</A>=20

    734. 

  734.   by <A class=3D"new" title=3D"User:Sergej B. (page does not exist)" =

    735. 

  735. href=3D"http://wiki.theory.org/index.php?title=3DUser:Sergej_B.&amp;actio=

    736. 

  736. n=3Dedit&amp;redlink=3D1">Sergej=20

    737. 

  737.   B.</A></LI>

    738. 

  738.   <LI> <A class=3D"external text" =

    739. 

  739. href=3D"http://demon.tw/my-work/javascript-bencode.html"=20

    740. 

  740.   rel=3D"nofollow">JavaScript</A> by <A class=3D"external text" =

    741. 

  741. href=3D"http://demon.tw/"=20

    742. 

  742.   rel=3D"nofollow">Demon</A>]</LI>

    743. 

  743.   <LI> <A class=3D"external text" =

    744. 

  744. href=3D"http://demon.tw/my-work/vbs-bencode.html"=20

    745. 

  745.   rel=3D"nofollow">VBScript</A> by <A class=3D"external text" =

    746. 

  746. href=3D"http://demon.tw/"=20

    747. 

  747.   rel=3D"nofollow">Demon</A>]</LI>

    748. 

  748.   <LI> <A class=3D"external text" =

    749. 

  749. href=3D"http://nakkaya.com/2009/11/02/decoding-bencoded-streams-in-clojur=

    750. 

  750. e/"=20

    751. 

  751.   rel=3D"nofollow">Clojure</A> by <A class=3D"new" title=3D"User:Nakkaya =

    752. 

  752. (page does not exist)"=20

    753. 

  753.   =

    754. 

  754. href=3D"http://wiki.theory.org/index.php?title=3DUser:Nakkaya&amp;action=3D=

    755. 

  755. edit&amp;redlink=3D1">nakkaya</A>

    756. 

  756.   </LI>

    757. 

  757.   <LI> <A title=3D"Decoding encoding bencoded data with erlang" =

    758. 

  758. href=3D"http://wiki.theory.org/Decoding_encoding_bencoded_data_with_erlan=

    759. 

  759. g">Erlang</A>

    760. 

  760.   </LI>

    761. 

  761.   <LI> <A title=3D"Decoding encoding bencoded data with PHP" =

    762. 

  762. href=3D"http://wiki.theory.org/Decoding_encoding_bencoded_data_with_PHP">=

    763. 

  763. PHP</A>

    764. 

  764.   </LI>

    765. 

  765.   <LI> <A class=3D"external text" =

    766. 

  766. href=3D"http://code.google.com/p/php-bencode-extension/"=20

    767. 

  767.   rel=3D"nofollow">PHP Extension</A></LI>

    768. 

  768.   <LI> <A class=3D"external text" =

    769. 

  769. href=3D"http://snipplr.com/view/37790/bencoding-encoder-and-decoder/"=20

    770. 

  770.   rel=3D"nofollow">C#</A> by <A class=3D"new" title=3D"User:SuprDewd =

    771. 

  771. (page does not exist)"=20

    772. 

  772.   =

    773. 

  773. href=3D"http://wiki.theory.org/index.php?title=3DUser:SuprDewd&amp;action=

    774. 

  774. =3Dedit&amp;redlink=3D1">SuprDewd</A>

    775. 

  775.   </LI>

    776. 

  776.   <LI> <A class=3D"external text" =

    777. 

  777. href=3D"http://cvs.savannah.gnu.org/viewvc/mldonkey/mldonkey/src/networks=

    778. 

  778. /bittorrent/bencode.ml?view=3Dmarkup"=20

    779. 

  779.   rel=3D"nofollow">OCaml</A> by <A class=3D"external text" =

    780. 

  780. href=3D"http://mldonkey.sourceforge.net/Main_Page"=20

    781. 

  781.   rel=3D"nofollow">MLDonkey</A></LI>

    782. 

  782.   <LI> <A class=3D"external text" =

    783. 

  783. href=3D"https://github.com/jsz/gorrent/tree/master/bencode"=20

    784. 

  784.   rel=3D"nofollow">Go</A> by <A class=3D"external text" =

    785. 

  785. href=3D"http://jsz.github.com/"=20

    786. 

  786.   rel=3D"nofollow">Leon Szpilewski</A></LI></UL>

    787. 

  787. <H2> <SPAN id=3D"Metainfo_File_Structure" class=3D"mw-headline"> =

    788. 

  788. Metainfo File=20

    789. 

  789. Structure </SPAN></H2>

    790. 

  790. <P>All data in a metainfo file is bencoded.  The specification for =

    791. 

  791. bencoding is=20

    792. 

  792. defined above.</P>

    793. 

  793. <P>The content of a metainfo file (the file ending in ".torrent") is a =

    794. 

  794. bencoded=20

    795. 

  795. dictionary, containing the keys listed below. All character string =

    796. 

  796. values are=20

    797. 

  797. UTF-8 encoded.</P>

    798. 

  798. <UL>

    799. 

  799.   <LI> <B>info</B>: a dictionary that describes the file(s) of the =

    800. 

  800. torrent. =20

    801. 

  801.   There are two possible forms: one for the case of a 'single-file' =

    802. 

  802. torrent with=20

    803. 

  803.   no directory structure, and one for the case of a 'multi-file' torrent =

    804. 

  804. (see=20

    805. 

  805.   below for details)</LI>

    806. 

  806.   <LI> <B>announce</B>: The announce URL of the tracker (string)</LI>

    807. 

  807.   <LI> <B>announce-list</B>: (optional) this is an extention to the =

    808. 

  808. official=20

    809. 

  809.   specification, offering backwards-compatibility.  (list of lists of =

    810. 

  810. strings).

    811. 

  811.   <UL>

    812. 

  812.     <LI>The official request for a specification change is <A =

    813. 

  813. class=3D"external text"=20

    814. 

  814.     href=3D"http://bittorrent.org/beps/bep_0012.html" =

    815. 

  815. rel=3D"nofollow">here</A>.

    816. 

  816.   </LI></UL></LI>

    817. 

  817.   <LI> <B>creation date</B>: (optional) the creation time of the =

    818. 

  818. torrent, in=20

    819. 

  819.   standard UNIX epoch format (integer, seconds since 1-Jan-1970 00:00:00 =

    820. 

  820. UTC)

    821. 

  821.   </LI>

    822. 

  822.   <LI> <B>comment</B>: (optional) free-form textual comments of the =

    823. 

  823. author=20

    824. 

  824.   (string)</LI>

    825. 

  825.   <LI> <B>created by</B>: (optional) name and version of the program =

    826. 

  826. used to=20

    827. 

  827.   create the .torrent (string)</LI>

    828. 

  828.   <LI> <B>encoding</B>: (optional) the string encoding format used to =

    829. 

  829. generate=20

    830. 

  830.   the <B>pieces</B> part of the <B>info</B> dictionary in the .torrent =

    831. 

  831. metafile=20

    832. 

  832.   (string)</LI></UL>

    833. 

  833. <H3> <SPAN id=3D"Info_Dictionary" class=3D"mw-headline">Info =

    834. 

  834. Dictionary</SPAN></H3>

    835. 

  835. <P>This section contains the field which are common to both mode, =

    836. 

  836. "single file"=20

    837. 

  837. and "multiple file".</P>

    838. 

  838. <UL>

    839. 

  839.   <LI> <B>piece length</B>: number of bytes in each piece (integer)</LI>

    840. 

  840.   <LI> <B>pieces</B>: string consisting of the concatenation of all =

    841. 

  841. 20-byte SHA1=20

    842. 

  842.   hash values, one per piece (byte string, i.e. not urlencoded)</LI>

    843. 

  843.   <LI> <B>private</B>: (optional) this field is an integer. If it is set =

    844. 

  844. to "1",=20

    845. 

  845.   the client MUST publish its presence to get other peers ONLY via the =

    846. 

  846. trackers=20

    847. 

  847.   explicitly described in the metainfo file. If this field is set to "0" =

    848. 

  848. or is=20

    849. 

  849.   not present, the client may obtain peer from other means, e.g. PEX =

    850. 

  850. peer=20

    851. 

  851.   exchange, dht. Here, "private" may be read as "no external peer =

    852. 

  852. source".

    853. 

  853.   <UL>

    854. 

  854.     <LI> <B>NOTE:</B> There is much debate surrounding private =

    855. 

  855. trackers.</LI>

    856. 

  856.     <LI> The official request for a specification change is <A =

    857. 

  857. class=3D"external text"=20

    858. 

  858.     href=3D"http://bittorrent.org/beps/bep_0027.html" =

    859. 

  859. rel=3D"nofollow">here</A>.

    860. 

  860. </LI>

    861. 

  861.     <LI> Azureus was the first client to respect private trackers, <A =

    862. 

  862. class=3D"external text"=20

    863. 

  863.     href=3D"http://www.azureuswiki.com/index.php/Secure_Torrents"=20

    864. 

  864.     rel=3D"nofollow">see their wiki</A> for more =

    865. 

  865. details.</LI></UL></LI></UL>

    866. 

  866. <H4> <SPAN id=3D"Info_in_Single_File_Mode" class=3D"mw-headline">Info in =

    867. 

  867. Single File=20

    868. 

  868. Mode</SPAN></H4>

    869. 

  869. <P>For the case of the <B>single-file</B> mode, the <B>info</B> =

    870. 

  870. dictionary=20

    871. 

  871. contains the following structure:</P>

    872. 

  872. <UL>

    873. 

  873.   <LI> <B>name</B>: the filename.  This is purely advisory. =

    874. 

  874. (string)</LI>

    875. 

  875.   <LI> <B>length</B>: length of the file in bytes (integer)</LI>

    876. 

  876.   <LI> <B>md5sum</B>: (optional) a 32-character hexadecimal string =

    877. 

  877. corresponding=20

    878. 

  878.   to the MD5 sum of the file.  This is not used by BitTorrent at all, =

    879. 

  879. but it is=20

    880. 

  880.   included by some programs for greater compatibility.</LI></UL>

    881. 

  881. <H4> <SPAN id=3D"Info_in_Multiple_File_Mode" class=3D"mw-headline">Info =

    882. 

  882. in Multiple=20

    883. 

  883. File Mode</SPAN></H4>

    884. 

  884. <P>For the case of the <B>multi-file</B> mode, the <B>info</B> =

    885. 

  885. dictionary=20

    886. 

  886. contains the following structure:</P>

    887. 

  887. <UL>

    888. 

  888.   <LI> <B>name</B>: the file path of the directory in which to store all =

    889. 

  889. the=20

    890. 

  890.   files.  This is purely advisory. (string)</LI>

    891. 

  891.   <LI> <B>files</B>: a list of dictionaries, one for each file. Each =

    892. 

  892. dictionary=20

    893. 

  893.   in this list contains the following keys:

    894. 

  894.   <UL>

    895. 

  895.     <LI> <B>length</B>: length of the file in bytes (integer)</LI>

    896. 

  896.     <LI> <B>md5sum</B>: (optional) a 32-character hexadecimal string=20

    897. 

  897.     corresponding to the MD5 sum of the file.  This is not used by =

    898. 

  898. BitTorrent at=20

    899. 

  899.     all, but it is included by some programs for greater =

    900. 

  900. compatibility.</LI>

    901. 

  901.     <LI> <B>path</B>: a list containing one or more string elements that =

    902. 

  902. 

    903. 

  903.     together represent the path and filename.  Each element in the list=20

    904. 

  904.     corresponds to either a directory name or (in the case of the final =

    905. 

  905. element)=20

    906. 

  906.     the filename.  For example, a the file "dir1/dir2/file.ext" would =

    907. 

  907. consist of=20

    908. 

  908.     three string elements: "dir1", "dir2", and "file.ext".  This is =

    909. 

  909. encoded as a=20

    910. 

  910.     bencoded list of strings such as=20

    911. 

  911.     =

    912. 

  912. <I>l<B>4</B>:dir1<B>4</B>:dir2<B>8</B>:file.ext<B>e</B></I></LI></UL></LI=

    913. 

  913. ></UL>

    914. 

  914. <H3> <SPAN id=3D"Notes" class=3D"mw-headline">Notes</SPAN></H3>

    915. 

  915. <UL>

    916. 

  916.   <LI> The <B>piece length</B> specifies the nominal piece size, and is =

    917. 

  917. usually=20

    918. 

  918.   a power of 2.  The piece size is typically chosen based on the total =

    919. 

  919. amount of=20

    920. 

  920.   file data in the torrent, and is constrained by the fact that =

    921. 

  921. too-large piece=20

    922. 

  922.   sizes cause inefficiency, and too-small piece sizes cause large =

    923. 

  923. .torrent=20

    924. 

  924.   metadata file.  Historically, piece size was chosen to result in a =

    925. 

  925. .torrent=20

    926. 

  926.   file no greater than approx. 50 - 75 kB (presumably to ease the load =

    927. 

  927. on the=20

    928. 

  928.   server hosting the torrent files). =20

    929. 

  929.   <UL>

    930. 

  930.     <LI>Current best-practice is to <I>keep the piece size to 512KB or =

    931. 

  931. less,</I>=20

    932. 

  932.     for torrents around 8-10GB, even if that results in a larger =

    933. 

  933. .torrent file. =20

    934. 

  934.     This results in a more efficient swarm for sharing files.   The most =

    935. 

  935. common=20

    936. 

  936.     sizes are 256 kB, 512 kB, and 1 MB.  </LI>

    937. 

  937.     <LI>Every piece is of equal length except for the final piece, which =

    938. 

  938. is=20

    939. 

  939.     irregular.  The number of pieces is thus determined by 'ceil( total =

    940. 

  940. length /=20

    941. 

  941.     piece size )'.  </LI>

    942. 

  942.     <LI>For the purposes of piece boundaries in the multi-file case, =

    943. 

  943. consider=20

    944. 

  944.     the file data as one long continuous stream, composed of the =

    945. 

  945. concatenation=20

    946. 

  946.     of each file in the order listed in the <I>files</I> list.  The =

    947. 

  947. number of=20

    948. 

  948.     pieces and their boundaries are then determined in the same manner =

    949. 

  949. as the=20

    950. 

  950.     case of a single file.  Pieces may overlap file =

    951. 

  951. boundaries.</LI></UL></LI>

    952. 

  952.   <LI> Each piece has a corresponding SHA1 hash of the data contained =

    953. 

  953. within=20

    954. 

  954.   that piece.  These hashes are concatenated to form the <I>pieces<B> =

    955. 

  955. value in=20

    956. 

  956.   the above </B></I><B>info</B> dictionary.  Note that this is =

    957. 

  957. <B>not</B> a list=20

    958. 

  958.   but rather a single string. The length of the string must be a =

    959. 

  959. multiple of 20.

    960. 

  960.   </LI></UL>

    961. 

  961. <H2> <SPAN id=3D"Tracker_HTTP.2FHTTPS_Protocol" class=3D"mw-headline"> =

    962. 

  962. Tracker=20

    963. 

  963. HTTP/HTTPS Protocol </SPAN></H2>

    964. 

  964. <P>The tracker is an HTTP/HTTPS service which responds to HTTP GET =

    965. 

  965. requests. The=20

    966. 

  966. requests include metrics from clients that help the tracker keep overall =

    967. 

  967. 

    968. 

  968. statistics about the torrent. The response includes a peer list that =

    969. 

  969. helps the=20

    970. 

  970. client participate in the torrent. The base URL consists of the =

    971. 

  971. "announce URL"=20

    972. 

  972. as defined in the metainfo (.torrent) file.  The parameters are then =

    973. 

  973. added to=20

    974. 

  974. this URL, using standard CGI methods (i.e. a '?' after the announce URL, =

    975. 

  975. 

    976. 

  976. followed by 'param=3Dvalue' sequences separated by '&amp;').</P>

    977. 

  977. <P>Note that all binary data in the URL (particularly info_hash and =

    978. 

  978. peer_id)=20

    979. 

  979. must be properly escaped.  This means any byte not in the set 0-9, a-z, =

    980. 

  980. A-Z,=20

    981. 

  981. '.', '-', '_' and '~', must be encoded using the "%nn" format, where nn =

    982. 

  982. is the=20

    983. 

  983. hexadecimal value of the byte. (See <A class=3D"external text" =

    984. 

  984. href=3D"http://www.faqs.org/rfcs/rfc1738.html"=20

    985. 

  985. rel=3D"nofollow">RFC1738</A> for details.) </P>

    986. 

  986. <P>For a 20-byte hash of=20

    987. 

  987. \x12\x34\x56\x78\x9a\xbc\xde\xf1\x23\x45\x67\x89\xab\xcd\xef\x12\x34\x56\=

    988. 

  988. x78\x9a,<BR>

    989. 

  989. The right encoded form =

    990. 

  990. is&nbsp;%124Vx%9A%BC%DE%F1%23Eg%89%AB%CD%EF%124Vx%9A</P>

    991. 

  991. <H3> <SPAN id=3D"Tracker_Request_Parameters" =

    992. 

  992. class=3D"mw-headline">Tracker Request=20

    993. 

  993. Parameters</SPAN></H3>

    994. 

  994. <P>The parameters used in the client-&gt;tracker GET request are as =

    995. 

  995. follows:</P>

    996. 

  996. <UL>

    997. 

  997.   <LI> <B>info_hash</B>: urlencoded 20-byte SHA1 hash of the =

    998. 

  998. <I>value</I> of the=20

    999. 

  999.   <I>info</I> key from the Metainfo file.  Note that the <I>value</I> =

    1000. 

  1000. will be a=20

    1001. 

  1001.   bencoded dictionary, given the definition of the <I>info</I> key =

    1002. 

  1002. above. </LI>

    1003. 

  1003.   <LI> <B><A=20

    1004. 

  1004.   =

    1005. 

  1005. href=3D"http://wiki.theory.org/BitTorrentSpecification#peer_id">peer_id</=

    1006. 

  1006. A></B>:=20

    1007. 

  1007.   urlencoded 20-byte string used as a unique ID for the client, =

    1008. 

  1008. generated by the=20

    1009. 

  1009.   client at startup.  This is allowed to be any value, and may be binary =

    1010. 

  1010. data. =20

    1011. 

  1011.   <I>There are currently no guidelines for generating this peer ID.  =

    1012. 

  1012. However,=20

    1013. 

  1013.   one may rightly presume that it must at least be unique for your local =

    1014. 

  1014. 

    1015. 

  1015.   machine, thus should probably incorporate things like process ID and =

    1016. 

  1016. perhaps a=20

    1017. 

  1017.   timestamp recorded at startup. See <A =

    1018. 

  1018. href=3D"http://wiki.theory.org/BitTorrentSpecification#peer_id">peer_id=20

    1019. 

  1019.   </A> below for common client encodings of this field.</I></LI>

    1020. 

  1020.   <LI> <B>port</B>: The port number that the client is listening on.  =

    1021. 

  1021. Ports=20

    1022. 

  1022.   reserved for BitTorrent are typically 6881-6889.  Clients may choose =

    1023. 

  1023. to give=20

    1024. 

  1024.   up if it cannot establish a port within this range.</LI>

    1025. 

  1025.   <LI> <B>uploaded</B>: The total amount uploaded (since the client sent =

    1026. 

  1026. the=20

    1027. 

  1027.   'started' event to the tracker) in base ten ASCII.  While not =

    1028. 

  1028. explicitly=20

    1029. 

  1029.   stated in the official specification, the concensus is that this =

    1030. 

  1030. should be the=20

    1031. 

  1031.   total number of bytes uploaded.</LI>

    1032. 

  1032.   <LI> <B>downloaded</B>: The total amount downloaded (since the client =

    1033. 

  1033. sent the=20

    1034. 

  1034.   'started' event to the tracker) in base ten ASCII.  While not =

    1035. 

  1035. explicitly=20

    1036. 

  1036.   stated in the official specification, the consensus is that this =

    1037. 

  1037. should be the=20

    1038. 

  1038.   total number of bytes downloaded.</LI>

    1039. 

  1039.   <LI> <B>left</B>: The number of bytes this client still has to =

    1040. 

  1040. download in=20

    1041. 

  1041.   base ten ASCII.</LI>

    1042. 

  1042.   <LI> <B>compact</B>: Setting this to 1 indicates that the client =

    1043. 

  1043. accepts a=20

    1044. 

  1044.   compact response. The announce-list is replaced by a peers string with =

    1045. 

  1045. 6 bytes=20

    1046. 

  1046.   per peer. The first four bytes are the host (in network byte order), =

    1047. 

  1047. the last=20

    1048. 

  1048.   two bytes are the port (again in network byte order). It should be =

    1049. 

  1049. noted that=20

    1050. 

  1050.   some trackers only support compact responses (for saving bandwidth) =

    1051. 

  1051. and either=20

    1052. 

  1052.   refuse requests without "compact=3D1" or simply send a compact =

    1053. 

  1053. response unless=20

    1054. 

  1054.   the request contains "compact=3D0" (in which case they will refuse the =

    1055. 

  1055. request.)

    1056. 

  1056.   </LI>

    1057. 

  1057.   <LI> <B>no_peer_id</B>: Indicates that the tracker can omit peer id =

    1058. 

  1058. field in=20

    1059. 

  1059.   announce-list dictionary. This option is ignored if compact is =

    1060. 

  1060. enabled.</LI>

    1061. 

  1061.   <LI> <B>event</B>: If specified, must be one of <I>started</I>,=20

    1062. 

  1062.   <I>completed</I>, <I>stopped</I>, (or empty which is the same as not =

    1063. 

  1063. being=20

    1064. 

  1064.   specified).  If not specified, then this request is one performed at =

    1065. 

  1065. regular=20

    1066. 

  1066.   intervals.

    1067. 

  1067.   <UL>

    1068. 

  1068.     <LI> <B>started</B>: The first request to the tracker <I>must</I> =

    1069. 

  1069. include=20

    1070. 

  1070.     the event key with this value.</LI>

    1071. 

  1071.     <LI> <B>stopped</B>: Must be sent to the tracker if the client is =

    1072. 

  1072. shutting=20

    1073. 

  1073.     down gracefully.</LI>

    1074. 

  1074.     <LI> <B>completed</B>: Must be sent to the tracker when the download =

    1075. 

  1075. 

    1076. 

  1076.     completes.  However, must not be sent if the download was already =

    1077. 

  1077. 100%=20

    1078. 

  1078.     complete when the client started.  Presumably, this is to allow the =

    1079. 

  1079. tracker=20

    1080. 

  1080.     to increment the "completed downloads" metric based solely on this =

    1081. 

  1081. event.

    1082. 

  1082.     </LI></UL></LI>

    1083. 

  1083.   <LI> <B>ip</B>: Optional.  The true IP address of the client machine, =

    1084. 

  1084. in=20

    1085. 

  1085.   dotted quad format or rfc3513 defined hexed IPv6 address.  <I>Notes: =

    1086. 

  1086. In=20

    1087. 

  1087.   general this parameter is not necessary as the address of the client =

    1088. 

  1088. can be=20

    1089. 

  1089.   determined from the IP address from which the HTTP request came.  The=20

    1090. 

  1090.   parameter is only needed in the case where the IP address that the =

    1091. 

  1091. request=20

    1092. 

  1092.   came in on is not the IP address of the client.  This happens if the =

    1093. 

  1093. client is=20

    1094. 

  1094.   communicating to the tracker through a proxy (or a transparent web=20

    1095. 

  1095.   proxy/cache.)  It also is necessary when both the client and the =

    1096. 

  1096. tracker are=20

    1097. 

  1097.   on the same local side of a NAT gateway.  The reason for this is that=20

    1098. 

  1098.   otherwise the tracker would give out the internal (RFC1918) address of =

    1099. 

  1099. the=20

    1100. 

  1100.   client, which is not routable.  Therefore the client must explicitly =

    1101. 

  1101. state its=20

    1102. 

  1102.   (external, routable) IP address to be given out to external peers.  =

    1103. 

  1103. Various=20

    1104. 

  1104.   trackers treat this parameter differently.  Some only honor it only if =

    1105. 

  1105. the IP=20

    1106. 

  1106.   address that the request came in on is in RFC1918 space.  Others honor =

    1107. 

  1107. it=20

    1108. 

  1108.   unconditionally, while others ignore it completely. In case of IPv6 =

    1109. 

  1109. address=20

    1110. 

  1110.   (e.g.: 2001:db8:1:2::100) it indicates only that client can =

    1111. 

  1111. communicate via=20

    1112. 

  1112.   IPv6.</I></LI>

    1113. 

  1113.   <LI> <B>numwant</B>: Optional.  Number of peers that the client would =

    1114. 

  1114. like to=20

    1115. 

  1115.   receive from the tracker.  This value is permitted to be zero.  If =

    1116. 

  1116. omitted,=20

    1117. 

  1117.   typically defaults to 50 peers.</LI>

    1118. 

  1118.   <LI> <B>key</B>: Optional. An additional client identification =

    1119. 

  1119. mechanism that=20

    1120. 

  1120.   is not shared with any peers. It is intended to allow a client to =

    1121. 

  1121. prove their=20

    1122. 

  1122.   identity should their IP address change.</LI>

    1123. 

  1123.   <LI> <B>trackerid</B>: Optional. If a previous announce contained a =

    1124. 

  1124. tracker=20

    1125. 

  1125.   id, it should be set here.</LI></UL>

    1126. 

  1126. <H3> <SPAN id=3D"Tracker_Response" class=3D"mw-headline">Tracker=20

    1127. 

  1127. Response</SPAN></H3>

    1128. 

  1128. <P>The tracker responds with "text/plain" document consisting of a =

    1129. 

  1129. bencoded=20

    1130. 

  1130. dictionary with the following keys:</P>

    1131. 

  1131. <UL>

    1132. 

  1132.   <LI> <B>failure reason</B>: If present, then no other keys may be =

    1133. 

  1133. present. =20

    1134. 

  1134.   The value is a human-readable error message as to why the request =

    1135. 

  1135. failed=20

    1136. 

  1136.   (string).</LI>

    1137. 

  1137.   <LI> <B>warning message</B>: (new, optional) Similar to failure =

    1138. 

  1138. reason, but=20

    1139. 

  1139.   the response still gets processed normally. The warning message is =

    1140. 

  1140. shown just=20

    1141. 

  1141.   like an error.</LI>

    1142. 

  1142.   <LI> <B>interval</B>: Interval in sec…
    1143.

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