/*
* Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdio.h>
#include <ipxe/http.h>
#include <ipxe/peermux.h>
/** @file
*
* Peer Content Caching and Retrieval (PeerDist) protocol
*
* This is quite possibly the ugliest protocol I have ever had the
* misfortune to encounter, and I've encountered multicast TFTP.
*/
/**
* Check whether or not to support PeerDist encoding for this request
*
* @v http HTTP transaction
* @ret supported PeerDist encoding is supported for this request
*/
static int http_peerdist_supported ( struct http_transaction *http ) {
/* Support PeerDist encoding only if we can directly access an
* underlying data transfer buffer. Direct access is required
* in order to support decryption of data received via the
* retrieval protocol (which provides the AES initialisation
* vector only after all of the encrypted data has been
* received).
*
* This test simultaneously ensures that we do not attempt to
* use PeerDist encoding on a request which is itself a
* PeerDist individual block download, since the individual
* block downloads do not themselves provide direct access to
* an underlying data transfer buffer.
*/
return ( xfer_buffer ( &http->xfer ) != NULL );
}
/**
* Format HTTP "X-P2P-PeerDist" header
*
* @v http HTTP transaction
* @v buf Buffer
* @v len Length of buffer
* @ret len Length of header value, or negative error
*/
static int http_format_p2p_peerdist ( struct http_transaction *http,
char *buf, size_t len ) {
int supported = http_peerdist_supported ( http );
int missing;
/* PeerDist wants us to inform the server whenever we make a
* request for data that was missing from local peers
* (presumably for statistical purposes only). We use the
* heuristic of assuming that the combination of "this request
* may not itself use PeerDist content encoding" and "this is
* a range request" probably indicates that we are making a
* PeerDist block raw range request for missing data.
*/
missing = ( http->request.range.len && ( ! supported ) );
/* Omit header if PeerDist encoding is not supported and we
* are not reporting a missing data request.
*/
if ( ! ( supported || missing ) )
return 0;
/* Construct header */
return snprintf ( buf, len, "Version=1.1%s",
( missing ? ", MissingDataRequest=true" : "" ) );
}
/** HTTP "X-P2P-PeerDist" header */
struct http_request_header http_request_p2p_peerdist __http_request_header = {
.name = "X-P2P-PeerDist",
.format = http_format_p2p_peerdist,
};
/**
* Format HTTP "X-P2P-PeerDistEx" header
*
* @v http HTTP transaction
* @v buf Buffer
* @v len Length of buffer
* @ret len Length of header value, or negative error
*/
static int http_format_p2p_peerdistex ( struct http_transaction *http,
char *buf, size_t len ) {
int supported = http_peerdist_supported ( http );
/* Omit header if PeerDist encoding is not supported */
if ( ! supported )
return 0;
/* Construct header */
return snprintf ( buf, len, ( "MinContentInformation=1.0, "
"MaxContentInformation=2.0" ) );
}
/** HTTP "X-P2P-PeerDist" header */
struct http_request_header http_request_p2p_peerdistex __http_request_header = {
.name = "X-P2P-PeerDistEx",
.format = http_format_p2p_peerdistex,
};
/**
* Initialise PeerDist content encoding
*
* @v http HTTP transaction
* @ret rc Return status code
*/
static int http_peerdist_init ( struct http_transaction *http ) {
return peermux_filter ( &http->content, &http->transfer, http->uri );
}
/** PeerDist HTTP content encoding */
struct http_content_encoding peerdist_encoding __http_content_encoding = {
.name = "peerdist",
.supported = http_peerdist_supported,
.init = http_peerdist_init,
};
