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/*
* nghttp3
*
* Copyright (c) 2019 nghttp3 contributors
* Copyright (c) 2013 nghttp2 contributors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef NGHTTP3_QPACK_HUFFMAN_H
#define NGHTTP3_QPACK_HUFFMAN_H
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#include <nghttp3/nghttp3.h>
typedef struct nghttp3_qpack_huffman_sym {
/* The number of bits in this code */
uint32_t nbits;
/* Huffman code aligned to LSB */
uint32_t code;
} nghttp3_qpack_huffman_sym;
extern const nghttp3_qpack_huffman_sym huffman_sym_table[];
size_t nghttp3_qpack_huffman_encode_count(const uint8_t *src, size_t len);
uint8_t *nghttp3_qpack_huffman_encode(uint8_t *dest, const uint8_t *src,
size_t srclen);
typedef enum nghttp3_qpack_huffman_decode_flag {
/* FSA accepts this state as the end of huffman encoding
sequence. */
NGHTTP3_QPACK_HUFFMAN_ACCEPTED = 1 << 14,
/* This state emits symbol */
NGHTTP3_QPACK_HUFFMAN_SYM = 1 << 15,
} nghttp3_qpack_huffman_decode_flag;
typedef struct nghttp3_qpack_huffman_decode_node {
/* fstate is the current huffman decoding state, which is actually
the node ID of internal huffman tree with
nghttp3_qpack_huffman_decode_flag OR-ed. We have 257 leaf nodes,
but they are identical to root node other than emitting a symbol,
so we have 256 internal nodes [1..256], inclusive. The node ID
256 is a special node and it is a terminal state that means
decoding failed. */
uint16_t fstate;
/* symbol if NGHTTP3_QPACK_HUFFMAN_SYM flag set */
uint8_t sym;
} nghttp3_qpack_huffman_decode_node;
typedef struct nghttp3_qpack_huffman_decode_context {
/* fstate is the current huffman decoding state. */
uint16_t fstate;
} nghttp3_qpack_huffman_decode_context;
extern const nghttp3_qpack_huffman_decode_node qpack_huffman_decode_table[][16];
void nghttp3_qpack_huffman_decode_context_init(
nghttp3_qpack_huffman_decode_context *ctx);
/*
* nghttp3_qpack_huffman_decode decodes huffman encoded byte string
* stored in |src| of length |srclen|. |ctx| is a decoding context.
* |ctx| remembers the decoding state, and caller can call this
* function multiple times to feed each chunk of huffman encoded
* substring. |fin| must be nonzero if |src| contains the last chunk
* of huffman string. The decoded string is written to the buffer
* pointed by |dest|. This function assumes that the buffer pointed
* by |dest| contains enough memory to store decoded byte string.
*
* This function returns the number of bytes written to |dest|, or one
* of the following negative error codes:
*
* NGHTTP3_ERR_QPACK_FATAL
* Could not decode huffman string.
*/
nghttp3_ssize
nghttp3_qpack_huffman_decode(nghttp3_qpack_huffman_decode_context *ctx,
uint8_t *dest, const uint8_t *src, size_t srclen,
int fin);
/*
* nghttp3_qpack_huffman_decode_failure_state returns nonzero if |ctx|
* indicates that huffman decoding context is in failure state.
*/
int nghttp3_qpack_huffman_decode_failure_state(
nghttp3_qpack_huffman_decode_context *ctx);
#endif /* NGHTTP3_QPACK_HUFFMAN_H */
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