cl-bencode

https://github.com/nja/cl-bencode.git

git clone 'https://github.com/nja/cl-bencode.git'

(ql:quickload :cl-bencode)
★5

Description

cl-bencode is a Common Lisp bencode library. Bencode is the encoding used by BitTorrent.

Features

cl-bencode supports all four different types of bencode values.

It's proven capable of roundtripping several torrents found in the wild.

String encoding

The bencode specification does not deal with character encodings. cl-bencode uses flexi-streams' external-formats for character encoding. The default is UTF-8. See http://weitz.de/flexi-streams/#external-formats

Binary strings

The parameter *binary-key-p* may hold a function. When decoding dictionary values, this function is passed a list, where the first element is the key of the value. If the dictionary was in turn a dictionary value, that key is the second element of the list, and so on. Should a dictionary be a value in a bencoded list, the corresponding element in the list will be the symbol :list. When the function return a true value, the dictionary value will be binary. Otherwise it will be decoded as a string.

The default function in *binary-key-p* returns true for the “pieces” value in the “info” dictionary. All other values are decoded as strings.

Example

CL-USER> (ql:quickload "bencode")
; ...
("bencode")
CL-USER> (with-open-file (stream "/tmp/torrent" 
                                 :element-type '(unsigned-byte 8))
           (bencode:decode stream))
#<HASH-TABLE :TEST EQUAL :COUNT 4 {1005E0E3D3}>
CL-USER> (gethash "announce" *)
"http://bttracker.debian.org:6969/announce"
T
CL-USER> (type-of (gethash "pieces" (gethash "info" **)))
(SIMPLE-ARRAY (UNSIGNED-BYTE 8) (88860))
CL-USER> (equalp (ironclad:digest-sequence :sha1 (bencode:encode *** nil))
                 (ironclad:digest-file :sha1 "/tmp/torrent"))
T
CL-USER> (asdf:test-system "bencode")
......................................
T
CL-USER>

Todo