Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 1 | /* |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 2 | * include/types/channel.h |
| 3 | * Channel management definitions, macros and inline functions. |
Willy Tarreau | 7c3c541 | 2009-12-13 15:53:05 +0100 | [diff] [blame] | 4 | * |
Willy Tarreau | a27dc19 | 2014-11-27 22:10:04 +0100 | [diff] [blame] | 5 | * Copyright (C) 2000-2014 Willy Tarreau - w@1wt.eu |
Willy Tarreau | 7c3c541 | 2009-12-13 15:53:05 +0100 | [diff] [blame] | 6 | * |
| 7 | * This library is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation, version 2.1 |
| 10 | * exclusively. |
| 11 | * |
| 12 | * This library is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with this library; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 21 | |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 22 | #ifndef _TYPES_CHANNEL_H |
| 23 | #define _TYPES_CHANNEL_H |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 24 | |
Willy Tarreau | e3ba5f0 | 2006-06-29 18:54:54 +0200 | [diff] [blame] | 25 | #include <common/config.h> |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 26 | #include <common/buffer.h> |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 27 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 28 | /* The CF_* macros designate Channel Flags, which may be ORed in the bit field |
| 29 | * member 'flags' in struct channel. Here we have several types of flags : |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 30 | * |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 31 | * - pure status flags, reported by the data layer, which must be cleared |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 32 | * before doing further I/O : |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 33 | * CF_*_NULL, CF_*_PARTIAL |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 34 | * |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 35 | * - pure status flags, reported by stream-interface layer, which must also |
| 36 | * be cleared before doing further I/O : |
| 37 | * CF_*_TIMEOUT, CF_*_ERROR |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 38 | * |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 39 | * - read-only indicators reported by lower data levels : |
| 40 | * CF_STREAMER, CF_STREAMER_FAST |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 41 | * |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 42 | * - write-once status flags reported by the stream-interface layer : |
| 43 | * CF_SHUTR, CF_SHUTW |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 44 | * |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 45 | * - persistent control flags managed only by application level : |
Willy Tarreau | b31c971 | 2012-11-11 23:05:39 +0100 | [diff] [blame] | 46 | * CF_SHUT*_NOW, CF_*_ENA |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 47 | * |
| 48 | * The flags have been arranged for readability, so that the read and write |
Willy Tarreau | 418fd47 | 2009-09-06 21:37:23 +0200 | [diff] [blame] | 49 | * bits have the same position in a byte (read being the lower byte and write |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 50 | * the second one). All flag names are relative to the channel. For instance, |
| 51 | * 'write' indicates the direction from the channel to the stream interface. |
Willy Tarreau | 5446940 | 2006-07-29 16:59:06 +0200 | [diff] [blame] | 52 | */ |
Willy Tarreau | e393fe2 | 2008-08-16 22:18:07 +0200 | [diff] [blame] | 53 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 54 | #define CF_READ_NULL 0x00000001 /* last read detected on producer side */ |
| 55 | #define CF_READ_PARTIAL 0x00000002 /* some data were read from producer */ |
| 56 | #define CF_READ_TIMEOUT 0x00000004 /* timeout while waiting for producer */ |
| 57 | #define CF_READ_ERROR 0x00000008 /* unrecoverable error on producer side */ |
| 58 | #define CF_READ_ACTIVITY (CF_READ_NULL|CF_READ_PARTIAL|CF_READ_ERROR) |
Willy Tarreau | 0f9f505 | 2006-07-29 17:39:25 +0200 | [diff] [blame] | 59 | |
Willy Tarreau | 644c101 | 2014-04-30 18:11:11 +0200 | [diff] [blame] | 60 | #define CF_WAKE_CONNECT 0x00000010 /* wake the task up after connect succeeds */ |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 61 | #define CF_SHUTR 0x00000020 /* producer has already shut down */ |
| 62 | #define CF_SHUTR_NOW 0x00000040 /* the producer must shut down for reads ASAP */ |
| 63 | #define CF_READ_NOEXP 0x00000080 /* producer should not expire */ |
Willy Tarreau | 5446940 | 2006-07-29 16:59:06 +0200 | [diff] [blame] | 64 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 65 | #define CF_WRITE_NULL 0x00000100 /* write(0) or connect() succeeded on consumer side */ |
| 66 | #define CF_WRITE_PARTIAL 0x00000200 /* some data were written to the consumer */ |
| 67 | #define CF_WRITE_TIMEOUT 0x00000400 /* timeout while waiting for consumer */ |
| 68 | #define CF_WRITE_ERROR 0x00000800 /* unrecoverable error on consumer side */ |
| 69 | #define CF_WRITE_ACTIVITY (CF_WRITE_NULL|CF_WRITE_PARTIAL|CF_WRITE_ERROR) |
Willy Tarreau | 5446940 | 2006-07-29 16:59:06 +0200 | [diff] [blame] | 70 | |
Willy Tarreau | d7ad9f5 | 2013-12-31 17:26:25 +0100 | [diff] [blame] | 71 | #define CF_WAKE_WRITE 0x00001000 /* wake the task up when there's write activity */ |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 72 | #define CF_SHUTW 0x00002000 /* consumer has already shut down */ |
| 73 | #define CF_SHUTW_NOW 0x00004000 /* the consumer must shut down for writes ASAP */ |
| 74 | #define CF_AUTO_CLOSE 0x00008000 /* producer can forward shutdown to other side */ |
Willy Tarreau | 5446940 | 2006-07-29 16:59:06 +0200 | [diff] [blame] | 75 | |
Willy Tarreau | b31c971 | 2012-11-11 23:05:39 +0100 | [diff] [blame] | 76 | /* When CF_SHUTR_NOW is set, it is strictly forbidden for the producer to alter |
| 77 | * the buffer contents. When CF_SHUTW_NOW is set, the consumer is free to perform |
| 78 | * a shutw() when it has consumed the last contents, otherwise the session processor |
| 79 | * will do it anyway. |
Willy Tarreau | 418fd47 | 2009-09-06 21:37:23 +0200 | [diff] [blame] | 80 | * |
| 81 | * The SHUT* flags work like this : |
| 82 | * |
| 83 | * SHUTR SHUTR_NOW meaning |
| 84 | * 0 0 normal case, connection still open and data is being read |
| 85 | * 0 1 closing : the producer cannot feed data anymore but can close |
| 86 | * 1 0 closed: the producer has closed its input channel. |
| 87 | * 1 1 impossible |
| 88 | * |
| 89 | * SHUTW SHUTW_NOW meaning |
| 90 | * 0 0 normal case, connection still open and data is being written |
| 91 | * 0 1 closing: the consumer can send last data and may then close |
| 92 | * 1 0 closed: the consumer has closed its output channel. |
| 93 | * 1 1 impossible |
| 94 | * |
Willy Tarreau | 520d95e | 2009-09-19 21:04:57 +0200 | [diff] [blame] | 95 | * The SHUTW_NOW flag should be set by the session processor when SHUTR and AUTO_CLOSE |
Willy Tarreau | b31c971 | 2012-11-11 23:05:39 +0100 | [diff] [blame] | 96 | * are both set. And it may also be set by the producer when it detects SHUTR while |
| 97 | * directly forwarding data to the consumer. |
Willy Tarreau | 418fd47 | 2009-09-06 21:37:23 +0200 | [diff] [blame] | 98 | * |
| 99 | * The SHUTR_NOW flag is mostly used to force the producer to abort when an error is |
| 100 | * detected on the consumer side. |
| 101 | */ |
| 102 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 103 | #define CF_STREAMER 0x00010000 /* the producer is identified as streaming data */ |
| 104 | #define CF_STREAMER_FAST 0x00020000 /* the consumer seems to eat the stream very fast */ |
Willy Tarreau | 0f9f505 | 2006-07-29 17:39:25 +0200 | [diff] [blame] | 105 | |
Willy Tarreau | 9dc1c61 | 2014-09-01 20:35:55 +0200 | [diff] [blame] | 106 | #define CF_WROTE_DATA 0x00040000 /* some data were sent from this buffer */ |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 107 | #define CF_ANA_TIMEOUT 0x00080000 /* the analyser timeout has expired */ |
| 108 | #define CF_READ_ATTACHED 0x00100000 /* the read side is attached for the first time */ |
| 109 | #define CF_KERN_SPLICING 0x00200000 /* kernel splicing desired for this channel */ |
| 110 | #define CF_READ_DONTWAIT 0x00400000 /* wake the task up after every read (eg: HTTP request) */ |
| 111 | #define CF_AUTO_CONNECT 0x00800000 /* consumer may attempt to establish a new connection */ |
Willy Tarreau | 9a2d154 | 2008-08-30 12:31:07 +0200 | [diff] [blame] | 112 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 113 | #define CF_DONT_READ 0x01000000 /* disable reading for now */ |
| 114 | #define CF_EXPECT_MORE 0x02000000 /* more data expected to be sent very soon (one-shoot) */ |
| 115 | #define CF_SEND_DONTWAIT 0x04000000 /* don't wait for sending data (one-shoot) */ |
| 116 | #define CF_NEVER_WAIT 0x08000000 /* never wait for sending data (permanent) */ |
Willy Tarreau | f1ba4b3 | 2009-10-17 14:37:52 +0200 | [diff] [blame] | 117 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 118 | #define CF_WAKE_ONCE 0x10000000 /* pretend there is activity on this channel (one-shoot) */ |
Willy Tarreau | ef573c0 | 2014-11-28 14:17:09 +0100 | [diff] [blame] | 119 | /* unused: 0x20000000, 0x40000000 */ |
| 120 | #define CF_ISRESP 0x80000000 /* 0 = request channel, 1 = response channel */ |
Willy Tarreau | 0499e35 | 2010-12-17 07:13:42 +0100 | [diff] [blame] | 121 | |
Willy Tarreau | fe3718a | 2008-11-30 18:14:12 +0100 | [diff] [blame] | 122 | /* Masks which define input events for stream analysers */ |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 123 | #define CF_MASK_ANALYSER (CF_READ_ATTACHED|CF_READ_ACTIVITY|CF_READ_TIMEOUT|CF_ANA_TIMEOUT|CF_WRITE_ACTIVITY|CF_WAKE_ONCE) |
Willy Tarreau | fe3718a | 2008-11-30 18:14:12 +0100 | [diff] [blame] | 124 | |
Willy Tarreau | 1d315ea | 2010-06-04 12:25:31 +0200 | [diff] [blame] | 125 | /* Mask for static flags which cause analysers to be woken up when they change */ |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 126 | #define CF_MASK_STATIC (CF_SHUTR|CF_SHUTW|CF_SHUTR_NOW|CF_SHUTW_NOW) |
Willy Tarreau | 3da77c5 | 2008-08-29 09:58:42 +0200 | [diff] [blame] | 127 | |
Willy Tarreau | 2df28e8 | 2008-08-17 15:20:19 +0200 | [diff] [blame] | 128 | |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 129 | /* Analysers (channel->analysers). |
Willy Tarreau | 2df28e8 | 2008-08-17 15:20:19 +0200 | [diff] [blame] | 130 | * Those bits indicate that there are some processing to do on the buffer |
Willy Tarreau | 70cb633 | 2008-12-07 11:28:08 +0100 | [diff] [blame] | 131 | * contents. It will probably evolve into a linked list later. Those |
Willy Tarreau | 2df28e8 | 2008-08-17 15:20:19 +0200 | [diff] [blame] | 132 | * analysers could be compared to higher level processors. |
Willy Tarreau | 8263d2b | 2012-08-28 00:06:31 +0200 | [diff] [blame] | 133 | * The field is blanked by channel_init() and only by analysers themselves |
Willy Tarreau | 2df28e8 | 2008-08-17 15:20:19 +0200 | [diff] [blame] | 134 | * afterwards. |
| 135 | */ |
Willy Tarreau | 74172ff | 2012-08-31 17:52:35 +0200 | [diff] [blame] | 136 | /* unused: 0x00000001 */ |
Willy Tarreau | 6e59577 | 2010-10-15 14:12:12 +0200 | [diff] [blame] | 137 | #define AN_REQ_INSPECT_FE 0x00000002 /* inspect request contents in the frontend */ |
| 138 | #define AN_REQ_WAIT_HTTP 0x00000004 /* wait for an HTTP request */ |
Willy Tarreau | 748179e | 2015-05-01 21:52:31 +0200 | [diff] [blame] | 139 | #define AN_REQ_HTTP_BODY 0x00000008 /* wait for HTTP request body */ |
| 140 | #define AN_REQ_HTTP_PROCESS_FE 0x00000010 /* process the frontend's HTTP part */ |
| 141 | #define AN_REQ_SWITCHING_RULES 0x00000020 /* apply the switching rules */ |
| 142 | #define AN_REQ_INSPECT_BE 0x00000040 /* inspect request contents in the backend */ |
| 143 | #define AN_REQ_HTTP_PROCESS_BE 0x00000080 /* process the backend's HTTP part */ |
| 144 | #define AN_REQ_SRV_RULES 0x00000100 /* use-server rules */ |
| 145 | #define AN_REQ_HTTP_INNER 0x00000200 /* inner processing of HTTP request */ |
| 146 | #define AN_REQ_HTTP_TARPIT 0x00000400 /* wait for end of HTTP tarpit */ |
Willy Tarreau | 4a5cade | 2012-04-05 21:09:48 +0200 | [diff] [blame] | 147 | #define AN_REQ_STICKING_RULES 0x00000800 /* table persistence matching */ |
| 148 | #define AN_REQ_PRST_RDP_COOKIE 0x00001000 /* persistence on rdp cookie */ |
| 149 | #define AN_REQ_HTTP_XFER_BODY 0x00002000 /* forward request body */ |
Thierry FOURNIER | b83862d | 2015-02-26 10:40:09 +0100 | [diff] [blame] | 150 | #define AN_REQ_ALL 0x00003ffe /* all of the request analysers */ |
Willy Tarreau | 2df28e8 | 2008-08-17 15:20:19 +0200 | [diff] [blame] | 151 | |
Willy Tarreau | b37c27e | 2009-10-18 22:53:08 +0200 | [diff] [blame] | 152 | /* response analysers */ |
| 153 | #define AN_RES_INSPECT 0x00010000 /* content inspection */ |
| 154 | #define AN_RES_WAIT_HTTP 0x00020000 /* wait for HTTP response */ |
| 155 | #define AN_RES_HTTP_PROCESS_BE 0x00040000 /* process backend's HTTP part */ |
| 156 | #define AN_RES_HTTP_PROCESS_FE 0x00040000 /* process frontend's HTTP part (same for now) */ |
Emeric Brun | 1d33b29 | 2010-01-04 15:47:17 +0100 | [diff] [blame] | 157 | #define AN_RES_STORE_RULES 0x00080000 /* table persistence matching */ |
Willy Tarreau | d98cf93 | 2009-12-27 22:54:55 +0100 | [diff] [blame] | 158 | #define AN_RES_HTTP_XFER_BODY 0x00100000 /* forward response body */ |
Willy Tarreau | b37c27e | 2009-10-18 22:53:08 +0200 | [diff] [blame] | 159 | |
Christopher Faulet | d7c9196 | 2015-04-30 11:48:27 +0200 | [diff] [blame] | 160 | #define AN_FLT_START_FE 0x01000000 |
| 161 | #define AN_FLT_START_BE 0x02000000 |
| 162 | #define AN_FLT_END 0x04000000 |
| 163 | #define AN_FLT_XFER_DATA 0x08000000 |
| 164 | |
| 165 | #define AN_FLT_ALL_FE 0x0d000000 |
| 166 | #define AN_FLT_ALL_BE 0x0e000000 |
Willy Tarreau | b37c27e | 2009-10-18 22:53:08 +0200 | [diff] [blame] | 167 | |
Willy Tarreau | 31971e5 | 2009-09-20 12:07:52 +0200 | [diff] [blame] | 168 | /* Magic value to forward infinite size (TCP, ...), used with ->to_forward */ |
Willy Tarreau | 983eb31 | 2013-12-28 19:16:26 +0100 | [diff] [blame] | 169 | #define CHN_INFINITE_FORWARD MAX_RANGE(unsigned int) |
Willy Tarreau | 31971e5 | 2009-09-20 12:07:52 +0200 | [diff] [blame] | 170 | |
Willy Tarreau | 01bf867 | 2008-12-07 18:03:29 +0100 | [diff] [blame] | 171 | |
Willy Tarreau | 7421efb | 2012-07-02 15:11:27 +0200 | [diff] [blame] | 172 | struct channel { |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 173 | unsigned int flags; /* CF_* */ |
Willy Tarreau | 0a8535f | 2012-10-13 10:05:56 +0200 | [diff] [blame] | 174 | unsigned int analysers; /* bit field indicating what to do on the channel */ |
| 175 | struct buffer *buf; /* buffer attached to the channel, always present but may move */ |
Willy Tarreau | 0a8535f | 2012-10-13 10:05:56 +0200 | [diff] [blame] | 176 | struct pipe *pipe; /* non-NULL only when data present */ |
| 177 | unsigned int to_forward; /* number of bytes to forward after out without a wake-up */ |
Willy Tarreau | b145c78 | 2014-02-09 17:45:16 +0100 | [diff] [blame] | 178 | unsigned short last_read; /* 16 lower bits of last read date (max pause=65s) */ |
Willy Tarreau | 0a8535f | 2012-10-13 10:05:56 +0200 | [diff] [blame] | 179 | unsigned char xfer_large; /* number of consecutive large xfers */ |
| 180 | unsigned char xfer_small; /* number of consecutive small xfers */ |
| 181 | unsigned long long total; /* total data read */ |
Willy Tarreau | 0c303ee | 2008-07-07 00:09:58 +0200 | [diff] [blame] | 182 | int rex; /* expiration date for a read, in ticks */ |
Willy Tarreau | 26ed74d | 2008-08-17 12:11:14 +0200 | [diff] [blame] | 183 | int wex; /* expiration date for a write or connect, in ticks */ |
Willy Tarreau | 0c303ee | 2008-07-07 00:09:58 +0200 | [diff] [blame] | 184 | int rto; /* read timeout, in ticks */ |
| 185 | int wto; /* write timeout, in ticks */ |
Willy Tarreau | 0a8535f | 2012-10-13 10:05:56 +0200 | [diff] [blame] | 186 | int analyse_exp; /* expiration date for current analysers (if set) */ |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 187 | }; |
| 188 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 189 | |
| 190 | /* Note about the channel structure |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 191 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 192 | A channel stores information needed to reliably transport data in a single |
| 193 | direction. It stores status flags, timeouts, counters, subscribed analysers, |
| 194 | pointers to a data producer and to a data consumer, and information about |
| 195 | the amount of data which is allowed to flow directly from the producer to |
| 196 | the consumer without waking up the analysers. |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 197 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 198 | A channel may buffer data into two locations : |
| 199 | - a visible buffer (->buf) |
| 200 | - an invisible buffer which right now consists in a pipe making use of |
| 201 | kernel buffers that cannot be tampered with. |
| 202 | |
| 203 | Data stored into the first location may be analysed and altered by analysers |
| 204 | while data stored in pipes is only aimed at being transported from one |
| 205 | network socket to another one without being subject to memory copies. This |
| 206 | buffer may only be used when both the socket layer and the data layer of the |
| 207 | producer and the consumer support it, which typically is the case with Linux |
| 208 | splicing over sockets, and when there are enough data to be transported |
| 209 | without being analyzed (transport of TCP/HTTP payload or tunnelled data, |
| 210 | which is indicated by ->to_forward). |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 211 | |
| 212 | In order not to mix data streams, the producer may only feed the invisible |
| 213 | data with data to forward, and only when the visible buffer is empty. The |
Willy Tarreau | 4b517ca | 2011-11-25 20:33:58 +0100 | [diff] [blame] | 214 | producer may not always be able to feed the invisible buffer due to platform |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 215 | limitations (lack of kernel support). |
| 216 | |
| 217 | Conversely, the consumer must always take data from the invisible data first |
| 218 | before ever considering visible data. There is no limit to the size of data |
| 219 | to consume from the invisible buffer, as platform-specific implementations |
| 220 | will rarely leave enough control on this. So any byte fed into the invisible |
| 221 | buffer is expected to reach the destination file descriptor, by any means. |
| 222 | However, it's the consumer's responsibility to ensure that the invisible |
| 223 | data has been entirely consumed before consuming visible data. This must be |
Willy Tarreau | 3eba98a | 2009-01-25 13:56:13 +0100 | [diff] [blame] | 224 | reflected by ->pipe->data. This is very important as this and only this can |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 225 | ensure strict ordering of data between buffers. |
| 226 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 227 | The producer is responsible for decreasing ->to_forward. The ->to_forward |
| 228 | parameter indicates how many bytes may be fed into either data buffer |
| 229 | without waking the parent up. The special value CHN_INFINITE_FORWARD is |
| 230 | never decreased nor increased. |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 231 | |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 232 | The buf->o parameter says how many bytes may be consumed from the visible |
| 233 | buffer. This parameter is updated by any buffer_write() as well as any data |
| 234 | forwarded through the visible buffer. Since the ->to_forward attribute |
| 235 | applies to data after buf->p, an analyser will not see a buffer which has a |
| 236 | non-null ->to_forward with buf->i > 0. A producer is responsible for raising |
| 237 | buf->o by min(to_forward, buf->i) when it injects data into the buffer. |
| 238 | |
| 239 | The consumer is responsible for decreasing ->buf->o when it sends data |
Willy Tarreau | 3eba98a | 2009-01-25 13:56:13 +0100 | [diff] [blame] | 240 | from the visible buffer, and ->pipe->data when it sends data from the |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 241 | invisible buffer. |
| 242 | |
| 243 | A real-world example consists in part in an HTTP response waiting in a |
| 244 | buffer to be forwarded. We know the header length (300) and the amount of |
| 245 | data to forward (content-length=9000). The buffer already contains 1000 |
| 246 | bytes of data after the 300 bytes of headers. Thus the caller will set |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 247 | buf->o to 300 indicating that it explicitly wants to send those data, and |
| 248 | set ->to_forward to 9000 (content-length). This value must be normalised |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 249 | immediately after updating ->to_forward : since there are already 1300 bytes |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 250 | in the buffer, 300 of which are already counted in buf->o, and that size |
| 251 | is smaller than ->to_forward, we must update buf->o to 1300 to flush the |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 252 | whole buffer, and reduce ->to_forward to 8000. After that, the producer may |
| 253 | try to feed the additional data through the invisible buffer using a |
| 254 | platform-specific method such as splice(). |
Willy Tarreau | 7c3c541 | 2009-12-13 15:53:05 +0100 | [diff] [blame] | 255 | |
| 256 | The ->to_forward entry is also used to detect whether we can fill the buffer |
| 257 | or not. The idea is that we need to save some space for data manipulation |
| 258 | (mainly header rewriting in HTTP) so we don't want to have a full buffer on |
| 259 | input before processing a request or response. Thus, we ensure that there is |
| 260 | always global.maxrewrite bytes of free space. Since we don't want to forward |
| 261 | chunks without filling the buffer, we rely on ->to_forward. When ->to_forward |
| 262 | is null, we may have some processing to do so we don't want to fill the |
| 263 | buffer. When ->to_forward is non-null, we know we don't care for at least as |
| 264 | many bytes. In the end, we know that each of the ->to_forward bytes will |
| 265 | eventually leave the buffer. So as long as ->to_forward is larger than |
| 266 | global.maxrewrite, we can fill the buffer. If ->to_forward is smaller than |
| 267 | global.maxrewrite, then we don't want to fill the buffer with more than |
Godbach | 2b8fd54 | 2013-09-30 11:23:10 +0800 | [diff] [blame] | 268 | buf->size - global.maxrewrite + ->to_forward. |
Willy Tarreau | 7c3c541 | 2009-12-13 15:53:05 +0100 | [diff] [blame] | 269 | |
Willy Tarreau | 4b517ca | 2011-11-25 20:33:58 +0100 | [diff] [blame] | 270 | A buffer may contain up to 5 areas : |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 271 | - the data waiting to be sent. These data are located between buf->p-o and |
| 272 | buf->p ; |
Willy Tarreau | 4b517ca | 2011-11-25 20:33:58 +0100 | [diff] [blame] | 273 | - the data to process and possibly transform. These data start at |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 274 | buf->p and may be up to ->i bytes long. |
| 275 | - the data to preserve. They start at ->p and stop at ->p+i. The limit |
| 276 | between the two solely depends on the protocol being analysed. |
Willy Tarreau | 4b517ca | 2011-11-25 20:33:58 +0100 | [diff] [blame] | 277 | - the spare area : it is the remainder of the buffer, which can be used to |
Willy Tarreau | 03cdb7c | 2012-08-27 23:14:58 +0200 | [diff] [blame] | 278 | store new incoming data. It starts at ->p+i and is up to ->size-i-o long. |
| 279 | It may be limited by global.maxrewrite. |
| 280 | - the reserved area : this is the area which must not be filled and is |
Willy Tarreau | 4b517ca | 2011-11-25 20:33:58 +0100 | [diff] [blame] | 281 | reserved for possible rewrites ; it is up to global.maxrewrite bytes |
| 282 | long. |
Willy Tarreau | 0abebcc | 2009-01-08 00:09:41 +0100 | [diff] [blame] | 283 | */ |
| 284 | |
Willy Tarreau | c7e4238 | 2012-08-24 19:22:53 +0200 | [diff] [blame] | 285 | #endif /* _TYPES_CHANNEL_H */ |
Willy Tarreau | baaee00 | 2006-06-26 02:48:02 +0200 | [diff] [blame] | 286 | |
| 287 | /* |
| 288 | * Local variables: |
| 289 | * c-indent-level: 8 |
| 290 | * c-basic-offset: 8 |
| 291 | * End: |
| 292 | */ |