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