Magnet-URI Webseeding

[milahu]

implement bittorrent/bittorrent.org#171

status: early draft

i need help to get from "parse magnet link with xs parameter" to "send http request to fetch metadata file"
should the http server be treated like a bittorrent peer?

so far, i tried to base exact_source_connection on web_connection_base (which is based on peer_connection)
but it should be based on http_connection (right?)
but i dont see where i should create the http_connection

i need "dont require files_checked to connect to webseeds" to reach my code
files_checked makes no sense when we have no metadata

currently the parser fails at

[1027] xxxxxxxxxxxxxxx peer [ 127.0.0.1:80 client: Unknown [ .]....S....i.|.....] ] [127.0.0.1:80] <<< exact_source_connection::on_receive [ loop step: m_parser.status_code() == -1 ]

this looks like exact_source_connection::m_parser is not an http parser...?
because recv_buffer contains a valid http response

HTTP/1.1 200 OK
Content-Length: 800
Connection: keep-alive

d8:announce30:udp://...

exact_source_connection examples:

./examples/exact_source_client "magnet:?xt=urn:btih:xxxxxxxxxxxxxxx&xs=http://127.0.0.1/cas/btih/xxxxxxxxxxxxxxx.torrent"
./examples/exact_source_client "magnet:?xt=urn:btih:xxxxxxxxxxxxxxx&cas=http://127.0.0.1/cas/"

this requires an http server on 127.0.0.1
serving metadata and content files under http://127.0.0.1/cas/

http://127.0.0.1/cas/btih/xxxxxxxxxxxxxxx.torrent
http://127.0.0.1/cas/btih/xxxxxxxxxxxxxxx/Some.Dir/Some.File.txt