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/*
* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2013 Tatsuhiro Tsujikawa
*
* 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.
*/
#include "nghttp2_hd_huffman.h"
#include <string.h>
#include <assert.h>
#include <stdio.h>
#include "nghttp2_hd.h"
#include "nghttp2_net.h"
size_t nghttp2_hd_huff_encode_count(const uint8_t *src, size_t len) {
size_t i;
size_t nbits = 0;
for (i = 0; i < len; ++i) {
nbits += huff_sym_table[src[i]].nbits;
}
/* pad the prefix of EOS (256) */
return (nbits + 7) / 8;
}
int nghttp2_hd_huff_encode(nghttp2_bufs *bufs, const uint8_t *src,
size_t srclen) {
const nghttp2_huff_sym *sym;
const uint8_t *end = src + srclen;
uint64_t code = 0;
uint32_t x;
size_t nbits = 0;
size_t avail;
int rv;
avail = nghttp2_bufs_cur_avail(bufs);
for (; src != end;) {
sym = &huff_sym_table[*src++];
code |= (uint64_t)sym->code << (32 - nbits);
nbits += sym->nbits;
if (nbits < 32) {
continue;
}
if (avail >= 4) {
x = htonl((uint32_t)(code >> 32));
memcpy(bufs->cur->buf.last, &x, 4);
bufs->cur->buf.last += 4;
avail -= 4;
code <<= 32;
nbits -= 32;
continue;
}
for (; nbits >= 8;) {
rv = nghttp2_bufs_addb(bufs, (uint8_t)(code >> 56));
if (rv != 0) {
return rv;
}
code <<= 8;
nbits -= 8;
}
avail = nghttp2_bufs_cur_avail(bufs);
}
for (; nbits >= 8;) {
rv = nghttp2_bufs_addb(bufs, (uint8_t)(code >> 56));
if (rv != 0) {
return rv;
}
code <<= 8;
nbits -= 8;
}
if (nbits) {
rv = nghttp2_bufs_addb(
bufs, (uint8_t)((uint8_t)(code >> 56) | ((1 << (8 - nbits)) - 1)));
if (rv != 0) {
return rv;
}
}
return 0;
}
void nghttp2_hd_huff_decode_context_init(nghttp2_hd_huff_decode_context *ctx) {
ctx->fstate = NGHTTP2_HUFF_ACCEPTED;
}
nghttp2_ssize nghttp2_hd_huff_decode(nghttp2_hd_huff_decode_context *ctx,
nghttp2_buf *buf, const uint8_t *src,
size_t srclen, int final) {
const uint8_t *end = src + srclen;
nghttp2_huff_decode node = {ctx->fstate, 0};
const nghttp2_huff_decode *t = &node;
uint8_t c;
/* We use the decoding algorithm described in
- http://graphics.ics.uci.edu/pub/Prefix.pdf [!!! NO LONGER VALID !!!]
- https://ics.uci.edu/~dan/pubs/Prefix.pdf
- https://github.com/nghttp2/nghttp2/files/15141264/Prefix.pdf */
for (; src != end;) {
c = *src++;
t = &huff_decode_table[t->fstate & 0x1ff][c >> 4];
if (t->fstate & NGHTTP2_HUFF_SYM) {
*buf->last++ = t->sym;
}
t = &huff_decode_table[t->fstate & 0x1ff][c & 0xf];
if (t->fstate & NGHTTP2_HUFF_SYM) {
*buf->last++ = t->sym;
}
}
ctx->fstate = t->fstate;
if (final && !(ctx->fstate & NGHTTP2_HUFF_ACCEPTED)) {
return NGHTTP2_ERR_HEADER_COMP;
}
return (nghttp2_ssize)srclen;
}
int nghttp2_hd_huff_decode_failure_state(nghttp2_hd_huff_decode_context *ctx) {
return ctx->fstate == 0x100;
}
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