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231 lines
9.4 KiB
231 lines
9.4 KiB
/*
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* include/haproxy/htx-t.h
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* This file declares the types and constants used the internal HTTP messages
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*
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* Copyright (C) 2018 HAProxy Technologies, Christopher Faulet <cfaulet@haproxy.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _HAPROXY_HTX_T_H
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#define _HAPROXY_HTX_T_H
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#include <haproxy/api.h>
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#include <haproxy/http-t.h>
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/*
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* The internal representation of an HTTP message, called HTX, is a structure
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* with useful information on the message followed by a contiguous array
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* containing parts of the message, called blocks. A block is composed of
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* metadata (htx_blk) and the associated payload. Blocks' metadata are stored
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* starting from the end of the array while their payload are stored at the
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* beginning. Blocks' metadata are often simply called blocks. it is a misuse of
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* language that's simplify explanations.
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*
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*
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* +-----+---------------+------------------------------+--------------+
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* | HTX | PAYLOADS ==> | | <== HTX_BLKs |
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* +-----+---------------+------------------------------+--------------+
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* ^
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* blocks[] (the beginning of the bocks array)
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*
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*
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* The blocks part remains linear and sorted. You may think about it as an array
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* with negative indexes. But, instead of using negative indexes, we use
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* positive positions to identify a block. This position is then converted to a
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* address relatively to the beginning of the blocks array.
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*
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*
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* .....--+------------------------------+-----+-----+
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* | ... | BLK | BLK |
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* .....--+------------------------------+-----+-----+
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* ^ ^
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* Addr of the block Addr of the block
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* at the position 1 at the position 0
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*
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*
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* The payloads part is a raw space that may wrap. You never access to a block's
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* payload directly. Instead you get a block to retrieve the address of its
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* payload. When no more space left between blocks and payloads parts, the free
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* space at the beginning, if any, is used.
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*
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*
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* +----------- WRAPPING ------------------------+
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* | |
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* V |
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* +-----+-------------+---------------+---------------++--------------+
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* | HTX | PAYLOAD ==> | | PAYLOADS ==X || X== HTX_BLKs |
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* +-----+-------------+---------------+---------------++--------------+
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*
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*
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* The blocks part, on its side, never wrap. If we have no space to allocate a
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* new block and if there is a hole at the beginning of the blocks part (so at
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* the end of the blocks array), we move back all blocks.x
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*
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*
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* ...+--------------+----------+ blocks ...+----------+--------------+
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* | X== HTX_BLKS | | defrag | | <== HTX_BLKS |
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* ...+--------------+----------+ =====> ...+----------+--------------+
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*
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*
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* At the end, if payload wrapping or blocks defragmentation is not enough, some
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* free space may be get back with a full defragmentation. This way, the holes in
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* the middle are not reusable but count in the available free space. The only
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* way to reuse this lost space is to fully defragmenate the HTX message.
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*
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* - * -
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*
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* An HTX block is as well a header as a body part or a trailer. For all these
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* types of block, a payload is attached to the block. It can also be a mark,
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* like the end-of-headers or end-of-message. For these blocks, there is no
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* payload but it count for a byte. It is important to not skip it when data are
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* forwarded. Metadata of an HTX block are composed of 2 fields :
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*
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* - .info : It a 32 bits field containing the block's type on 4 bits
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* followed by the payload length. See below for details.
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*
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* - .addr : The payload's address, if any, relatively to the beginning the
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* array used to store the HTX message itself.
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*
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* htx_blk.info representation :
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*
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* 0b 0000 0000 0000 0000 0000 0000 0000 0000
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* ---- ------------------------ ---------
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* type value (1 MB max) name length (header/trailer)
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* ----------------------------------
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* data length (256 MB max)
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* (body, method, path, version, status, reason)
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*
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* types :
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* - 0000 = request start-line
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* - 0001 = response start-line
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* - 0010 = header
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* - 0011 = pseudo-header ou "special" header
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* - 0100 = end-of-headers
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* - 0101 = data
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* - 0110 = trailer
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* - 0111 = end-of-trailers
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* - 1000 = end-of-message
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* ...
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* - 1111 = unused
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*
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*/
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/* HTX start-line flags */
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#define HTX_SL_F_NONE 0x00000000
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#define HTX_SL_F_IS_RESP 0x00000001 /* It is the response start-line (unset means the request one) */
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#define HTX_SL_F_XFER_LEN 0x00000002 /* The message xfer size can be dertermined */
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#define HTX_SL_F_XFER_ENC 0x00000004 /* The transfer-encoding header was found in message */
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#define HTX_SL_F_CLEN 0x00000008 /* The content-length header was found in message */
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#define HTX_SL_F_CHNK 0x00000010 /* The message payload is chunked */
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#define HTX_SL_F_VER_11 0x00000020 /* The message indicates version 1.1 or above */
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#define HTX_SL_F_BODYLESS 0x00000040 /* The message has no body (content-length = 0) */
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#define HTX_SL_F_HAS_SCHM 0x00000080 /* The scheme is explicitly specified */
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#define HTX_SL_F_SCHM_HTTP 0x00000100 /* The scheme HTTP should be used */
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#define HTX_SL_F_SCHM_HTTPS 0x00000200 /* The scheme HTTPS should be used */
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#define HTX_SL_F_HAS_AUTHORITY 0x00000400 /* The request authority is explicitly specified */
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#define HTX_SL_F_NORMALIZED_URI 0x00000800 /* The received URI is normalized (an implicit absolute-uri form) */
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/* HTX flags */
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#define HTX_FL_NONE 0x00000000
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#define HTX_FL_PARSING_ERROR 0x00000001 /* Set when a parsing error occurred */
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#define HTX_FL_PROCESSING_ERROR 0x00000002 /* Set when a processing error occurred */
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/* 0x00000004 unused */
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#define HTX_FL_PROXY_RESP 0x00000008 /* Set when the response was generated by HAProxy */
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#define HTX_FL_EOI 0x00000010 /* Set when end-of-input is reached from the HTX point of view
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* (at worst, on the EOM block is missing)
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*/
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/* HTX block's type (max 15). */
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enum htx_blk_type {
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HTX_BLK_REQ_SL = 0, /* Request start-line */
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HTX_BLK_RES_SL = 1, /* Response start-line */
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HTX_BLK_HDR = 2, /* header name/value block */
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HTX_BLK_EOH = 3, /* end-of-headers block */
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HTX_BLK_DATA = 4, /* data block */
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HTX_BLK_TLR = 5, /* trailer name/value block */
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HTX_BLK_EOT = 6, /* end-of-trailers block */
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HTX_BLK_EOM = 7, /* end-of-message block */
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/* 8 .. 14 unused */
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HTX_BLK_UNUSED = 15, /* unused/removed block */
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};
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/* One HTX block descriptor */
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struct htx_blk {
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uint32_t addr; /* relative storage address of the block's payload */
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uint32_t info; /* information about the block (type, length) */
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};
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/* Composite return value used by some HTX functions */
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struct htx_ret {
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int32_t ret; /* A numerical value */
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struct htx_blk *blk; /* An HTX block */
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};
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/* HTX start-line */
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struct htx_sl {
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unsigned int flags; /* HTX_SL_F_* */
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union {
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struct {
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enum http_meth_t meth; /* method */
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} req;
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struct {
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uint16_t status; /* status code */
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} res;
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} info;
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/* XXX 2 bytes unused */
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int32_t hdrs_bytes; /* Bytes held by all headers, as seen by the mux
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* during parsing, from this start-line to the
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* corresponding EOH. -1 if unknown */
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unsigned int len[3]; /* length of different parts of the start-line */
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char l[VAR_ARRAY];
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};
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/* Internal representation of an HTTP message */
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struct htx {
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uint32_t size; /* the array size, in bytes, used to store the HTTP message itself */
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uint32_t data; /* the data size, in bytes. To known to total size used by all allocated
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* blocks (blocks and their contents), you need to add size used by blocks,
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* i.e. [ used * sizeof(struct htx_blk *) ] */
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int32_t tail; /* newest inserted block. -1 if the HTX message is empty */
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int32_t head; /* oldest inserted block. -1 if the HTX message is empty */
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int32_t first; /* position of the first block to (re)start the analyse. -1 if unset. */
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uint32_t tail_addr; /* start address of the free space in front of the the blocks table */
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uint32_t head_addr; /* start address of the free space at the beginning */
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uint32_t end_addr; /* end address of the free space at the beginning */
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uint64_t extra; /* known bytes amount remaining to receive */
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uint32_t flags; /* HTX_FL_* */
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/* XXX 4 bytes unused */
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/* Blocks representing the HTTP message itself */
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char blocks[VAR_ARRAY] __attribute__((aligned(8)));
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};
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#endif /* _HAPROXY_HTX_T_H */
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/*
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* Local variables:
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* c-indent-level: 8
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* c-basic-offset: 8
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* End:
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*/
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