266 lines
7.5 KiB
C
266 lines
7.5 KiB
C
/*
|
|
* nghttp2 - HTTP/2.0 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 "nghttp2_hd.h"
|
|
|
|
extern const nghttp2_huff_sym req_huff_sym_table[];
|
|
extern const int16_t req_huff_decode_table[][256];
|
|
|
|
extern const nghttp2_huff_sym res_huff_sym_table[];
|
|
extern const int16_t res_huff_decode_table[][256];
|
|
|
|
/*
|
|
* Returns next 8 bits of data from |in|, starting |bitoff| bits
|
|
* offset. If there are fewer bits left than |bitoff|, the left bits
|
|
* with padded with 0 are returned. The |bitoff| must be strictly less
|
|
* than 8.
|
|
*/
|
|
static uint8_t get_prefix_byte(const uint8_t *in, size_t len, size_t bitoff)
|
|
{
|
|
uint8_t b;
|
|
size_t bitleft;
|
|
if(bitoff == 0) {
|
|
return *in;
|
|
}
|
|
bitleft = 8 - bitoff;
|
|
b = (*in & ((1 << bitleft) - 1)) << bitoff;
|
|
if(len > 1) {
|
|
b |= *(in + 1) >> bitleft;
|
|
}
|
|
return b;
|
|
}
|
|
|
|
/*
|
|
* Decodes next byte from input |in| with length |len|, starting
|
|
* |bitoff| bit offset.
|
|
*
|
|
* This function returns the decoded symbol number (0-255 and 256 for
|
|
* special terminal symbol) if it succeeds, or -1.
|
|
*/
|
|
static int huff_decode(const uint8_t *in, size_t len, size_t bitoff,
|
|
const nghttp2_huff_sym *huff_sym_table,
|
|
const huff_decode_table_type *huff_decode_table)
|
|
{
|
|
int rv = 0;
|
|
size_t len_orig = len;
|
|
if(len == 0) {
|
|
return -1;
|
|
}
|
|
for(;;) {
|
|
rv = huff_decode_table[rv][get_prefix_byte(in, len, bitoff)];
|
|
if(rv >= 0) {
|
|
break;
|
|
}
|
|
/* Negative return value means we need to lookup next table. */
|
|
rv = -rv;
|
|
++in;
|
|
--len;
|
|
if(len == 0) {
|
|
return -1;
|
|
}
|
|
}
|
|
if(bitoff + huff_sym_table[rv].nbits > len_orig * 8) {
|
|
return -1;
|
|
}
|
|
return rv;
|
|
}
|
|
|
|
/*
|
|
* Returns next LSB aligned |nbits| bits from huffman symbol |sym|,
|
|
* starting |codebitoff| bit offset (from beginning of code sequence,
|
|
* so it could be more than 8).
|
|
*/
|
|
static uint8_t huff_get_lsb_aligned(const nghttp2_huff_sym *sym,
|
|
size_t codebitoff,
|
|
size_t nbits)
|
|
{
|
|
size_t codeidx = codebitoff / 8;
|
|
uint8_t a = sym->code[codeidx];
|
|
size_t localbitoff = codebitoff & 0x7;
|
|
size_t bitleft = 8 - localbitoff;
|
|
|
|
if(bitleft >= nbits) {
|
|
return (a >> (bitleft - nbits)) & ((1 << nbits) - 1);
|
|
} else {
|
|
size_t right = nbits - bitleft;
|
|
a &= ((1 << bitleft) - 1);
|
|
a <<= right;
|
|
if((sym->nbits + 7) / 8 > codeidx + 1) {
|
|
a |= sym->code[codeidx + 1] >> (8 - right);
|
|
}
|
|
return a;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Encodes huffman code |sym| into |*dest_ptr|,starting |bitoff|
|
|
* offset. The |bitoff| must be strictly less than 8. At the end of
|
|
* the process, the |*dest_ptr| is updated and points where next
|
|
* output should be placed. The bit offset of the pointed location is
|
|
* returned.
|
|
*/
|
|
static size_t huff_encode_sym(uint8_t **dest_ptr, size_t bitoff,
|
|
const nghttp2_huff_sym *sym)
|
|
{
|
|
size_t b = 0;
|
|
if(bitoff == 0) **dest_ptr = 0;
|
|
**dest_ptr |= huff_get_lsb_aligned(sym, b, 8 - bitoff);
|
|
b += 8 - bitoff;
|
|
++*dest_ptr;
|
|
for(; b < sym->nbits; b += 8, ++*dest_ptr) {
|
|
**dest_ptr = huff_get_lsb_aligned(sym, b, 8);
|
|
}
|
|
bitoff = 8 - (b - sym->nbits);
|
|
if(bitoff > 0) {
|
|
--*dest_ptr;
|
|
}
|
|
return bitoff;
|
|
}
|
|
|
|
size_t nghttp2_hd_huff_encode_count(const uint8_t *src, size_t len,
|
|
nghttp2_hd_side side)
|
|
{
|
|
size_t i;
|
|
size_t nbits = 0;
|
|
const nghttp2_huff_sym *huff_sym_table;
|
|
|
|
if(side == NGHTTP2_HD_SIDE_REQUEST) {
|
|
huff_sym_table = req_huff_sym_table;
|
|
} else {
|
|
huff_sym_table = res_huff_sym_table;
|
|
}
|
|
for(i = 0; i < len; ++i) {
|
|
nbits += huff_sym_table[src[i]].nbits;
|
|
}
|
|
/* pad the prefix of EOS (256) */
|
|
return (nbits + 7) / 8;
|
|
}
|
|
|
|
ssize_t nghttp2_hd_huff_encode(uint8_t *dest, size_t destlen,
|
|
const uint8_t *src, size_t srclen,
|
|
nghttp2_hd_side side)
|
|
{
|
|
int bitoff = 0;
|
|
uint8_t *dest_first = dest;
|
|
size_t i;
|
|
const nghttp2_huff_sym *huff_sym_table;
|
|
|
|
if(side == NGHTTP2_HD_SIDE_REQUEST) {
|
|
huff_sym_table = req_huff_sym_table;
|
|
} else {
|
|
huff_sym_table = res_huff_sym_table;
|
|
}
|
|
for(i = 0; i < srclen; ++i) {
|
|
const nghttp2_huff_sym *sym = &huff_sym_table[src[i]];
|
|
bitoff = huff_encode_sym(&dest, bitoff, sym);
|
|
}
|
|
/* 256 is special terminal symbol, pad with its prefix */
|
|
if(bitoff > 0) {
|
|
*dest |= huff_sym_table[256].code[0] >> bitoff;
|
|
}
|
|
return dest - dest_first + (bitoff > 0);
|
|
}
|
|
|
|
ssize_t nghttp2_hd_huff_decode_count(const uint8_t *src, size_t srclen,
|
|
nghttp2_hd_side side)
|
|
{
|
|
size_t bitoff = 0;
|
|
size_t i, j;
|
|
const nghttp2_huff_sym *huff_sym_table;
|
|
const huff_decode_table_type *huff_decode_table;
|
|
|
|
if(side == NGHTTP2_HD_SIDE_REQUEST) {
|
|
huff_sym_table = req_huff_sym_table;
|
|
huff_decode_table = req_huff_decode_table;
|
|
} else {
|
|
huff_sym_table = res_huff_sym_table;
|
|
huff_decode_table = res_huff_decode_table;
|
|
}
|
|
j = 0;
|
|
for(i = 0; i < srclen;) {
|
|
int rv = huff_decode(src + i, srclen - i, bitoff,
|
|
huff_sym_table, huff_decode_table);
|
|
if(rv == -1) {
|
|
/* TODO Check prefix of EOS */
|
|
if(i + 1 == srclen && bitoff > 0) {
|
|
break;
|
|
}
|
|
return -1;
|
|
}
|
|
if(rv == 256) {
|
|
/* 256 is special terminal symbol */
|
|
break;
|
|
}
|
|
j++;
|
|
bitoff += huff_sym_table[rv].nbits;
|
|
i += bitoff / 8;
|
|
bitoff &= 0x7;
|
|
}
|
|
return j;
|
|
}
|
|
|
|
ssize_t nghttp2_hd_huff_decode(uint8_t *dest, size_t destlen,
|
|
const uint8_t *src, size_t srclen,
|
|
nghttp2_hd_side side)
|
|
{
|
|
size_t bitoff = 0;
|
|
size_t i, j;
|
|
const nghttp2_huff_sym *huff_sym_table;
|
|
const huff_decode_table_type *huff_decode_table;
|
|
|
|
if(side == NGHTTP2_HD_SIDE_REQUEST) {
|
|
huff_sym_table = req_huff_sym_table;
|
|
huff_decode_table = req_huff_decode_table;
|
|
} else {
|
|
huff_sym_table = res_huff_sym_table;
|
|
huff_decode_table = res_huff_decode_table;
|
|
}
|
|
j = 0;
|
|
for(i = 0; i < srclen;) {
|
|
int rv = huff_decode(src + i, srclen - i, bitoff,
|
|
huff_sym_table, huff_decode_table);
|
|
if(rv == -1) {
|
|
/* TODO Check prefix of EOS */
|
|
if(i + 1 == srclen && bitoff > 0) {
|
|
break;
|
|
}
|
|
return -1;
|
|
}
|
|
if(rv == 256) {
|
|
/* 256 is special terminal symbol */
|
|
break;
|
|
}
|
|
dest[j++] = rv;
|
|
bitoff += huff_sym_table[rv].nbits;
|
|
i += bitoff / 8;
|
|
bitoff &= 0x7;
|
|
}
|
|
return j;
|
|
}
|