1 /* 2 * include/types/channel.h 3 * Channel management definitions, macros and inline functions. 4 * 5 * Copyright (C) 2000-2014 Willy Tarreau - w@1wt.eu 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 */ 21 22 #ifndef _TYPES_CHANNEL_H 23 #define _TYPES_CHANNEL_H 24 25 #include <common/config.h> 26 #include <common/buffer.h> 27 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 : 30 * 31 * - pure status flags, reported by the data layer, which must be cleared 32 * before doing further I/O : 33 * CF_*_NULL, CF_*_PARTIAL 34 * 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 38 * 39 * - read-only indicators reported by lower data levels : 40 * CF_STREAMER, CF_STREAMER_FAST 41 * 42 * - write-once status flags reported by the stream-interface layer : 43 * CF_SHUTR, CF_SHUTW 44 * 45 * - persistent control flags managed only by application level : 46 * CF_SHUT*_NOW, CF_*_ENA 47 * 48 * The flags have been arranged for readability, so that the read and write 49 * bits have the same position in a byte (read being the lower byte and write 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. 52 */ 53 54 #define CF_READ_NULL 0x00000001 /* last read detected on producer side */ 55 #define CF_READ_PARTIAL 0x00000002 /* some data were read from producer or a read exception occurred */ 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) 59 60 #define CF_WAKE_CONNECT 0x00000010 /* wake the task up after connect succeeds */ 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 */ 64 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) 70 71 #define CF_WAKE_WRITE 0x00001000 /* wake the task up when there's write activity */ 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 */ 75 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. 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 * 95 * The SHUTW_NOW flag should be set by the session processor when SHUTR and AUTO_CLOSE 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. 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 */ 102 103 #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 */ 105 106 #define CF_WROTE_DATA 0x00040000 /* some data were sent from this buffer */ 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 */ 112 113 #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) */ 117 118 #define CF_WAKE_ONCE 0x10000000 /* pretend there is activity on this channel (one-shoot) */ 119 #define CF_FLT_ANALYZE 0x20000000 /* at least one filter is still analyzing this channel */ 120 #define CF_EOI 0x40000000 /* end-of-input has been reached */ 121 #define CF_ISRESP 0x80000000 /* 0 = request channel, 1 = response channel */ 122 123 /* Masks which define input events for stream analysers */ 124 #define CF_MASK_ANALYSER (CF_READ_ATTACHED|CF_READ_ACTIVITY|CF_READ_TIMEOUT|CF_ANA_TIMEOUT|CF_WRITE_ACTIVITY|CF_WAKE_ONCE) 125 126 /* Mask for static flags which cause analysers to be woken up when they change */ 127 #define CF_MASK_STATIC (CF_SHUTR|CF_SHUTW|CF_SHUTR_NOW|CF_SHUTW_NOW) 128 129 130 /* Analysers (channel->analysers). 131 * Those bits indicate that there are some processing to do on the buffer 132 * contents. It will probably evolve into a linked list later. Those 133 * analysers could be compared to higher level processors. 134 * The field is blanked by channel_init() and only by analysers themselves 135 * afterwards. 136 */ 137 /* AN_REQ_FLT_START_FE: 0x00000001 */ 138 #define AN_REQ_INSPECT_FE 0x00000002 /* inspect request contents in the frontend */ 139 #define AN_REQ_WAIT_HTTP 0x00000004 /* wait for an HTTP request */ 140 #define AN_REQ_HTTP_BODY 0x00000008 /* wait for HTTP request body */ 141 #define AN_REQ_HTTP_PROCESS_FE 0x00000010 /* process the frontend's HTTP part */ 142 #define AN_REQ_SWITCHING_RULES 0x00000020 /* apply the switching rules */ 143 /* AN_REQ_FLT_START_BE: 0x00000040 */ 144 #define AN_REQ_INSPECT_BE 0x00000080 /* inspect request contents in the backend */ 145 #define AN_REQ_HTTP_PROCESS_BE 0x00000100 /* process the backend's HTTP part */ 146 #define AN_REQ_HTTP_TARPIT 0x00000200 /* wait for end of HTTP tarpit */ 147 #define AN_REQ_SRV_RULES 0x00000400 /* use-server rules */ 148 #define AN_REQ_HTTP_INNER 0x00000800 /* inner processing of HTTP request */ 149 #define AN_REQ_PRST_RDP_COOKIE 0x00001000 /* persistence on rdp cookie */ 150 #define AN_REQ_STICKING_RULES 0x00002000 /* table persistence matching */ 151 /* AN_REQ_FLT_HTTP_HDRS: 0x00004000 */ 152 #define AN_REQ_HTTP_XFER_BODY 0x00008000 /* forward request body */ 153 #define AN_REQ_WAIT_CLI 0x00010000 154 /* AN_REQ_FLT_XFER_DATA: 0x00020000 */ 155 /* AN_REQ_FLT_END: 0x00040000 */ 156 #define AN_REQ_ALL 0x0001bfbe /* all of the request analysers */ 157 158 /* response analysers */ 159 /* AN_RES_FLT_START_FE: 0x00080000 */ 160 /* AN_RES_FLT_START_BE: 0x00100000 */ 161 #define AN_RES_INSPECT 0x00200000 /* content inspection */ 162 #define AN_RES_WAIT_HTTP 0x00400000 /* wait for HTTP response */ 163 #define AN_RES_STORE_RULES 0x00800000 /* table persistence matching */ 164 #define AN_RES_HTTP_PROCESS_BE 0x01000000 /* process backend's HTTP part */ 165 #define AN_RES_HTTP_PROCESS_FE 0x01000000 /* process frontend's HTTP part (same for now) */ 166 /* AN_RES_FLT_HTTP_HDRS: 0x02000000 */ 167 #define AN_RES_HTTP_XFER_BODY 0x04000000 /* forward response body */ 168 #define AN_RES_WAIT_CLI 0x08000000 169 /* AN_RES_FLT_XFER_DATA: 0x10000000 */ 170 /* AN_RES_FLT_END: 0x20000000 */ 171 #define AN_RES_ALL 0x0de00000 /* all of the response analysers */ 172 173 /* filters interleaved with analysers, see above */ 174 #define AN_REQ_FLT_START_FE 0x00000001 175 #define AN_REQ_FLT_START_BE 0x00000040 176 #define AN_REQ_FLT_HTTP_HDRS 0x00004000 177 #define AN_REQ_FLT_XFER_DATA 0x00020000 178 #define AN_REQ_FLT_END 0x00040000 179 180 #define AN_RES_FLT_START_FE 0x00080000 181 #define AN_RES_FLT_START_BE 0x00100000 182 #define AN_RES_FLT_HTTP_HDRS 0x02000000 183 #define AN_RES_FLT_XFER_DATA 0x10000000 184 #define AN_RES_FLT_END 0x20000000 185 186 /* Magic value to forward infinite size (TCP, ...), used with ->to_forward */ 187 #define CHN_INFINITE_FORWARD MAX_RANGE(unsigned int) 188 189 190 struct channel { 191 unsigned int flags; /* CF_* */ 192 unsigned int analysers; /* bit field indicating what to do on the channel */ 193 struct buffer buf; /* buffer attached to the channel, always present but may move */ 194 struct pipe *pipe; /* non-NULL only when data present */ 195 size_t output; /* part of buffer which is to be forwarded */ 196 unsigned int to_forward; /* number of bytes to forward after out without a wake-up */ 197 unsigned short last_read; /* 16 lower bits of last read date (max pause=65s) */ 198 unsigned char xfer_large; /* number of consecutive large xfers */ 199 unsigned char xfer_small; /* number of consecutive small xfers */ 200 unsigned long long total; /* total data read */ 201 int rex; /* expiration date for a read, in ticks */ 202 int wex; /* expiration date for a write or connect, in ticks */ 203 int rto; /* read timeout, in ticks */ 204 int wto; /* write timeout, in ticks */ 205 int analyse_exp; /* expiration date for current analysers (if set) */ 206 }; 207 208 209 /* Note about the channel structure 210 211 A channel stores information needed to reliably transport data in a single 212 direction. It stores status flags, timeouts, counters, subscribed analysers, 213 pointers to a data producer and to a data consumer, and information about 214 the amount of data which is allowed to flow directly from the producer to 215 the consumer without waking up the analysers. 216 217 A channel may buffer data into two locations : 218 - a visible buffer (->buf) 219 - an invisible buffer which right now consists in a pipe making use of 220 kernel buffers that cannot be tampered with. 221 222 Data stored into the first location may be analysed and altered by analysers 223 while data stored in pipes is only aimed at being transported from one 224 network socket to another one without being subject to memory copies. This 225 buffer may only be used when both the socket layer and the data layer of the 226 producer and the consumer support it, which typically is the case with Linux 227 splicing over sockets, and when there are enough data to be transported 228 without being analyzed (transport of TCP/HTTP payload or tunnelled data, 229 which is indicated by ->to_forward). 230 231 In order not to mix data streams, the producer may only feed the invisible 232 data with data to forward, and only when the visible buffer is empty. The 233 producer may not always be able to feed the invisible buffer due to platform 234 limitations (lack of kernel support). 235 236 Conversely, the consumer must always take data from the invisible data first 237 before ever considering visible data. There is no limit to the size of data 238 to consume from the invisible buffer, as platform-specific implementations 239 will rarely leave enough control on this. So any byte fed into the invisible 240 buffer is expected to reach the destination file descriptor, by any means. 241 However, it's the consumer's responsibility to ensure that the invisible 242 data has been entirely consumed before consuming visible data. This must be 243 reflected by ->pipe->data. This is very important as this and only this can 244 ensure strict ordering of data between buffers. 245 246 The producer is responsible for decreasing ->to_forward. The ->to_forward 247 parameter indicates how many bytes may be fed into either data buffer 248 without waking the parent up. The special value CHN_INFINITE_FORWARD is 249 never decreased nor increased. 250 251 The buf->o parameter says how many bytes may be consumed from the visible 252 buffer. This parameter is updated by any buffer_write() as well as any data 253 forwarded through the visible buffer. Since the ->to_forward attribute 254 applies to data after buf->p, an analyser will not see a buffer which has a 255 non-null ->to_forward with buf->i > 0. A producer is responsible for raising 256 buf->o by min(to_forward, buf->i) when it injects data into the buffer. 257 258 The consumer is responsible for decreasing ->buf->o when it sends data 259 from the visible buffer, and ->pipe->data when it sends data from the 260 invisible buffer. 261 262 A real-world example consists in part in an HTTP response waiting in a 263 buffer to be forwarded. We know the header length (300) and the amount of 264 data to forward (content-length=9000). The buffer already contains 1000 265 bytes of data after the 300 bytes of headers. Thus the caller will set 266 buf->o to 300 indicating that it explicitly wants to send those data, and 267 set ->to_forward to 9000 (content-length). This value must be normalised 268 immediately after updating ->to_forward : since there are already 1300 bytes 269 in the buffer, 300 of which are already counted in buf->o, and that size 270 is smaller than ->to_forward, we must update buf->o to 1300 to flush the 271 whole buffer, and reduce ->to_forward to 8000. After that, the producer may 272 try to feed the additional data through the invisible buffer using a 273 platform-specific method such as splice(). 274 275 The ->to_forward entry is also used to detect whether we can fill the buffer 276 or not. The idea is that we need to save some space for data manipulation 277 (mainly header rewriting in HTTP) so we don't want to have a full buffer on 278 input before processing a request or response. Thus, we ensure that there is 279 always global.maxrewrite bytes of free space. Since we don't want to forward 280 chunks without filling the buffer, we rely on ->to_forward. When ->to_forward 281 is null, we may have some processing to do so we don't want to fill the 282 buffer. When ->to_forward is non-null, we know we don't care for at least as 283 many bytes. In the end, we know that each of the ->to_forward bytes will 284 eventually leave the buffer. So as long as ->to_forward is larger than 285 global.maxrewrite, we can fill the buffer. If ->to_forward is smaller than 286 global.maxrewrite, then we don't want to fill the buffer with more than 287 buf->size - global.maxrewrite + ->to_forward. 288 289 A buffer may contain up to 5 areas : 290 - the data waiting to be sent. These data are located between buf->p-o and 291 buf->p ; 292 - the data to process and possibly transform. These data start at 293 buf->p and may be up to ->i bytes long. 294 - the data to preserve. They start at ->p and stop at ->p+i. The limit 295 between the two solely depends on the protocol being analysed. 296 - the spare area : it is the remainder of the buffer, which can be used to 297 store new incoming data. It starts at ->p+i and is up to ->size-i-o long. 298 It may be limited by global.maxrewrite. 299 - the reserved area : this is the area which must not be filled and is 300 reserved for possible rewrites ; it is up to global.maxrewrite bytes 301 long. 302 */ 303 304 #endif /* _TYPES_CHANNEL_H */ 305 306 /* 307 * Local variables: 308 * c-indent-level: 8 309 * c-basic-offset: 8 310 * End: 311 */ 312