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/*
*
* Copyright 2015-2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_TABLE_H
#define GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_TABLE_H
#include <grpc/support/port_platform.h>
#include <grpc/support/slice.h>
#include "src/core/lib/transport/metadata.h"
/* HPACK header table */
/* last index in the static table */
#define GRPC_CHTTP2_LAST_STATIC_ENTRY 61
/* Initial table size as per the spec */
#define GRPC_CHTTP2_INITIAL_HPACK_TABLE_SIZE 4096
/* Maximum table size that we'll use */
#define GRPC_CHTTP2_MAX_HPACK_TABLE_SIZE GRPC_CHTTP2_INITIAL_HPACK_TABLE_SIZE
/* Per entry overhead bytes as per the spec */
#define GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD 32
#if 0
/* Maximum number of entries we could possibly fit in the table, given defined
overheads */
#define GRPC_CHTTP2_MAX_TABLE_COUNT \
((GRPC_CHTTP2_MAX_HPACK_TABLE_SIZE + GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD - 1) / \
GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD)
#endif
/* hpack decoder table */
typedef struct {
/* the first used entry in ents */
uint32_t first_ent;
/* how many entries are in the table */
uint32_t num_ents;
/* the amount of memory used by the table, according to the hpack algorithm */
uint32_t mem_used;
/* the max memory allowed to be used by the table, according to the hpack
algorithm */
uint32_t max_bytes;
/* the currently agreed size of the table, according to the hpack algorithm */
uint32_t current_table_bytes;
/* Maximum number of entries we could possibly fit in the table, given defined
overheads */
uint32_t max_entries;
/* Number of entries allocated in ents */
uint32_t cap_entries;
/* a circular buffer of headers - this is stored in the opposite order to
what hpack specifies, in order to simplify table management a little...
meaning lookups need to SUBTRACT from the end position */
grpc_mdelem **ents;
grpc_mdelem *static_ents[GRPC_CHTTP2_LAST_STATIC_ENTRY];
} grpc_chttp2_hptbl;
/* initialize a hpack table */
void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl);
void grpc_chttp2_hptbl_destroy(grpc_chttp2_hptbl *tbl);
void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
uint32_t max_bytes);
int grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
uint32_t bytes);
/* lookup a table entry based on its hpack index */
grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
uint32_t index);
/* add a table entry to the index */
int grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl,
grpc_mdelem *md) GRPC_MUST_USE_RESULT;
/* Find a key/value pair in the table... returns the index in the table of the
most similar entry, or 0 if the value was not found */
typedef struct {
uint32_t index;
int has_value;
} grpc_chttp2_hptbl_find_result;
grpc_chttp2_hptbl_find_result grpc_chttp2_hptbl_find(
const grpc_chttp2_hptbl *tbl, grpc_mdelem *md);
#endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_TABLE_H */
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