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Diffstat (limited to '')
-rw-r--r-- | lib/nghttp3_qpack_huffman.h | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/lib/nghttp3_qpack_huffman.h b/lib/nghttp3_qpack_huffman.h new file mode 100644 index 0000000..fc3bc7b --- /dev/null +++ b/lib/nghttp3_qpack_huffman.h @@ -0,0 +1,108 @@ +/* + * 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 */ |