1 /*
2 * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 *
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25
26 #include <stdio.h>
27 #include <ipxe/http.h>
28 #include <ipxe/settings.h>
29 #include <ipxe/peermux.h>
30
31 /** @file
32 *
33 * Peer Content Caching and Retrieval (PeerDist) protocol
34 *
35 * This is quite possibly the ugliest protocol I have ever had the
36 * misfortune to encounter, and I've encountered multicast TFTP.
37 */
38
39 /** PeerDist is globally enabled */
40 static long peerdist_enabled = 1;
41
42 /**
43 * Check whether or not to support PeerDist encoding for this request
44 *
45 * @v http HTTP transaction
46 * @ret supported PeerDist encoding is supported for this request
47 */
http_peerdist_supported(struct http_transaction * http)48 static int http_peerdist_supported ( struct http_transaction *http ) {
49
50 /* Allow PeerDist to be globally enabled/disabled */
51 if ( ! peerdist_enabled )
52 return 0;
53
54 /* Support PeerDist encoding only if we can directly access an
55 * underlying data transfer buffer. Direct access is required
56 * in order to support decryption of data received via the
57 * retrieval protocol (which provides the AES initialisation
58 * vector only after all of the encrypted data has been
59 * received).
60 *
61 * This test simultaneously ensures that we do not attempt to
62 * use PeerDist encoding on a request which is itself a
63 * PeerDist individual block download, since the individual
64 * block downloads do not themselves provide direct access to
65 * an underlying data transfer buffer.
66 */
67 return ( xfer_buffer ( &http->xfer ) != NULL );
68 }
69
70 /**
71 * Format HTTP "X-P2P-PeerDist" header
72 *
73 * @v http HTTP transaction
74 * @v buf Buffer
75 * @v len Length of buffer
76 * @ret len Length of header value, or negative error
77 */
http_format_p2p_peerdist(struct http_transaction * http,char * buf,size_t len)78 static int http_format_p2p_peerdist ( struct http_transaction *http,
79 char *buf, size_t len ) {
80 int supported = http_peerdist_supported ( http );
81 int missing;
82
83 /* PeerDist wants us to inform the server whenever we make a
84 * request for data that was missing from local peers
85 * (presumably for statistical purposes only). We use the
86 * heuristic of assuming that the combination of "this request
87 * may not itself use PeerDist content encoding" and "this is
88 * a range request" probably indicates that we are making a
89 * PeerDist block raw range request for missing data.
90 */
91 missing = ( http->request.range.len && ( ! supported ) );
92
93 /* Omit header if PeerDist encoding is not supported and we
94 * are not reporting a missing data request.
95 */
96 if ( ! ( supported || missing ) )
97 return 0;
98
99 /* Construct header */
100 return snprintf ( buf, len, "Version=1.1%s",
101 ( missing ? ", MissingDataRequest=true" : "" ) );
102 }
103
104 /** HTTP "X-P2P-PeerDist" header */
105 struct http_request_header http_request_p2p_peerdist __http_request_header = {
106 .name = "X-P2P-PeerDist",
107 .format = http_format_p2p_peerdist,
108 };
109
110 /**
111 * Format HTTP "X-P2P-PeerDistEx" header
112 *
113 * @v http HTTP transaction
114 * @v buf Buffer
115 * @v len Length of buffer
116 * @ret len Length of header value, or negative error
117 */
http_format_p2p_peerdistex(struct http_transaction * http,char * buf,size_t len)118 static int http_format_p2p_peerdistex ( struct http_transaction *http,
119 char *buf, size_t len ) {
120 int supported = http_peerdist_supported ( http );
121
122 /* Omit header if PeerDist encoding is not supported */
123 if ( ! supported )
124 return 0;
125
126 /* Construct header */
127 return snprintf ( buf, len, ( "MinContentInformation=1.0, "
128 "MaxContentInformation=2.0" ) );
129 }
130
131 /** HTTP "X-P2P-PeerDist" header */
132 struct http_request_header http_request_p2p_peerdistex __http_request_header = {
133 .name = "X-P2P-PeerDistEx",
134 .format = http_format_p2p_peerdistex,
135 };
136
137 /**
138 * Initialise PeerDist content encoding
139 *
140 * @v http HTTP transaction
141 * @ret rc Return status code
142 */
http_peerdist_init(struct http_transaction * http)143 static int http_peerdist_init ( struct http_transaction *http ) {
144
145 return peermux_filter ( &http->content, &http->transfer, http->uri );
146 }
147
148 /** PeerDist HTTP content encoding */
149 struct http_content_encoding peerdist_encoding __http_content_encoding = {
150 .name = "peerdist",
151 .supported = http_peerdist_supported,
152 .init = http_peerdist_init,
153 };
154
155 /** PeerDist enabled setting */
156 const struct setting peerdist_setting __setting ( SETTING_MISC, peerdist ) = {
157 .name = "peerdist",
158 .description = "PeerDist enabled",
159 .type = &setting_type_int8,
160 };
161
162 /**
163 * Apply PeerDist settings
164 *
165 * @ret rc Return status code
166 */
apply_peerdist_settings(void)167 static int apply_peerdist_settings ( void ) {
168
169 /* Fetch global PeerDist enabled setting */
170 if ( fetch_int_setting ( NULL, &peerdist_setting,
171 &peerdist_enabled ) < 0 ) {
172 peerdist_enabled = 1;
173 }
174 DBGC ( &peerdist_enabled, "PEERDIST is %s\n",
175 ( peerdist_enabled ? "enabled" : "disabled" ) );
176
177 return 0;
178 }
179
180 /** PeerDist settings applicator */
181 struct settings_applicator peerdist_applicator __settings_applicator = {
182 .apply = apply_peerdist_settings,
183 };
184