2013-10-14 16:38:12 +02:00
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/*
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* nghttp2 - HTTP/2.0 C Library
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*
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* Copyright (c) 2013 Tatsuhiro Tsujikawa
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "nghttp2_hd_huffman.h"
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#include <string.h>
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#include <assert.h>
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2013-12-19 14:54:34 +01:00
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#include <stdio.h>
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2013-10-14 16:38:12 +02:00
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#include "nghttp2_hd.h"
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extern const nghttp2_huff_sym req_huff_sym_table[];
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2014-01-24 13:56:19 +01:00
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extern const nghttp2_huff_decode req_huff_decode_table[][16];
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2013-10-14 16:38:12 +02:00
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extern const nghttp2_huff_sym res_huff_sym_table[];
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2014-01-24 13:56:19 +01:00
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extern const nghttp2_huff_decode res_huff_decode_table[][16];
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2013-10-14 16:38:12 +02:00
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/*
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2013-12-19 14:54:34 +01:00
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* Encodes huffman code |sym| into |*dest_ptr|, whose least |rembits|
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* bits are not filled yet. The |rembits| must be in range [1, 8],
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* inclusive. At the end of the process, the |*dest_ptr| is updated
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* and points where next output should be placed. The number of
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* unfilled bits in the pointed location is returned.
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2013-10-14 16:38:12 +02:00
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*/
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2013-12-19 14:54:34 +01:00
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static size_t huff_encode_sym(uint8_t **dest_ptr, size_t rembits,
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2013-10-14 16:38:12 +02:00
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const nghttp2_huff_sym *sym)
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{
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2013-12-19 14:54:34 +01:00
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size_t nbits = sym->nbits;
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for(;;) {
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if(rembits > nbits) {
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**dest_ptr |= sym->code << (rembits - nbits);
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rembits -= nbits;
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break;
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}
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**dest_ptr |= sym->code >> (nbits - rembits);
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++*dest_ptr;
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nbits -= rembits;
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rembits = 8;
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if(nbits == 0) {
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break;
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}
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**dest_ptr = 0;
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2013-10-14 16:38:12 +02:00
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}
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2013-12-19 14:54:34 +01:00
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return rembits;
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2013-10-14 16:38:12 +02:00
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}
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size_t nghttp2_hd_huff_encode_count(const uint8_t *src, size_t len,
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nghttp2_hd_side side)
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{
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size_t i;
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size_t nbits = 0;
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const nghttp2_huff_sym *huff_sym_table;
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2013-10-20 17:44:39 +02:00
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if(side == NGHTTP2_HD_SIDE_REQUEST) {
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2013-10-14 16:38:12 +02:00
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huff_sym_table = req_huff_sym_table;
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} else {
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huff_sym_table = res_huff_sym_table;
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}
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for(i = 0; i < len; ++i) {
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nbits += huff_sym_table[src[i]].nbits;
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}
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2013-10-21 16:56:14 +02:00
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/* pad the prefix of EOS (256) */
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return (nbits + 7) / 8;
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2013-10-14 16:38:12 +02:00
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}
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ssize_t nghttp2_hd_huff_encode(uint8_t *dest, size_t destlen,
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const uint8_t *src, size_t srclen,
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nghttp2_hd_side side)
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{
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2013-12-19 14:54:34 +01:00
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int rembits = 8;
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2013-10-14 16:38:12 +02:00
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uint8_t *dest_first = dest;
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size_t i;
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const nghttp2_huff_sym *huff_sym_table;
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2013-10-20 17:44:39 +02:00
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if(side == NGHTTP2_HD_SIDE_REQUEST) {
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2013-10-14 16:38:12 +02:00
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huff_sym_table = req_huff_sym_table;
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} else {
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huff_sym_table = res_huff_sym_table;
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}
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for(i = 0; i < srclen; ++i) {
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const nghttp2_huff_sym *sym = &huff_sym_table[src[i]];
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2013-12-19 14:54:34 +01:00
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if(rembits == 8) {
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*dest = 0;
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}
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rembits = huff_encode_sym(&dest, rembits, sym);
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2013-10-14 16:38:12 +02:00
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}
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2013-10-21 16:56:14 +02:00
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/* 256 is special terminal symbol, pad with its prefix */
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2013-12-19 14:54:34 +01:00
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if(rembits < 8) {
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const nghttp2_huff_sym *sym = &huff_sym_table[256];
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*dest |= sym->code >> (sym->nbits - rembits);
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++dest;
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2013-10-21 16:56:14 +02:00
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}
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2013-12-19 14:54:34 +01:00
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return dest - dest_first;
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2013-10-14 16:38:12 +02:00
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}
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2014-01-07 13:44:56 +01:00
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ssize_t nghttp2_hd_huff_decode(uint8_t **dest_ptr,
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2013-10-14 16:38:12 +02:00
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const uint8_t *src, size_t srclen,
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nghttp2_hd_side side)
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{
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2014-01-24 13:56:19 +01:00
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size_t i, j, k;
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2013-10-14 16:38:12 +02:00
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const huff_decode_table_type *huff_decode_table;
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2014-01-07 13:44:56 +01:00
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uint8_t *dest = NULL;
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size_t destlen = 0;
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int rv;
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2014-01-24 13:56:19 +01:00
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int16_t state = 0;
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const nghttp2_huff_decode *t = NULL;
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2013-10-14 16:38:12 +02:00
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2014-01-24 13:56:19 +01:00
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/* We use the decoding algorithm described in
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http://graphics.ics.uci.edu/pub/Prefix.pdf */
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2013-10-20 17:44:39 +02:00
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if(side == NGHTTP2_HD_SIDE_REQUEST) {
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2013-10-14 16:38:12 +02:00
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huff_decode_table = req_huff_decode_table;
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} else {
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huff_decode_table = res_huff_decode_table;
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}
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j = 0;
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2014-01-24 13:56:19 +01:00
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for(i = 0; i < srclen; ++i) {
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uint8_t in = src[i] >> 4;
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for(k = 0; k < 2; ++k) {
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t = &huff_decode_table[state][in];
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if(t->state == -1) {
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rv = NGHTTP2_ERR_HEADER_COMP;
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2014-01-07 13:44:56 +01:00
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goto fail;
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}
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2014-01-24 13:56:19 +01:00
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if(t->flags & NGHTTP2_HUFF_SYM) {
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if(destlen == j) {
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size_t new_len = j == 0 ? 32 : j * 2;
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uint8_t *new_dest = realloc(dest, new_len);
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if(new_dest == NULL) {
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rv = NGHTTP2_ERR_NOMEM;
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goto fail;
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}
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dest = new_dest;
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destlen = new_len;
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}
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dest[j++] = t->sym;
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}
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state = t->state;
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in = src[i] & 0xf;
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2013-10-14 16:38:12 +02:00
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}
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2014-01-24 13:56:19 +01:00
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}
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if(srclen && (t->flags & NGHTTP2_HUFF_ACCEPTED) == 0) {
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rv = NGHTTP2_ERR_HEADER_COMP;
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goto fail;
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2013-10-14 16:38:12 +02:00
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}
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2014-01-07 13:44:56 +01:00
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*dest_ptr = dest;
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2013-10-14 16:38:12 +02:00
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return j;
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2014-01-07 13:44:56 +01:00
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fail:
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free(dest);
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return rv;
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2013-10-14 16:38:12 +02:00
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}
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