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/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include "src/core/ext/transport/chttp2/transport/bin_encoder.h"
#include <string.h>
#include <grpc/support/log.h>
#include "src/core/ext/transport/chttp2/transport/huffsyms.h"
static const char alphabet[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
typedef struct {
uint16_t bits;
uint8_t length;
} b64_huff_sym;
static const b64_huff_sym huff_alphabet[64] = {
{0x21, 6}, {0x5d, 7}, {0x5e, 7}, {0x5f, 7}, {0x60, 7}, {0x61, 7},
{0x62, 7}, {0x63, 7}, {0x64, 7}, {0x65, 7}, {0x66, 7}, {0x67, 7},
{0x68, 7}, {0x69, 7}, {0x6a, 7}, {0x6b, 7}, {0x6c, 7}, {0x6d, 7},
{0x6e, 7}, {0x6f, 7}, {0x70, 7}, {0x71, 7}, {0x72, 7}, {0xfc, 8},
{0x73, 7}, {0xfd, 8}, {0x3, 5}, {0x23, 6}, {0x4, 5}, {0x24, 6},
{0x5, 5}, {0x25, 6}, {0x26, 6}, {0x27, 6}, {0x6, 5}, {0x74, 7},
{0x75, 7}, {0x28, 6}, {0x29, 6}, {0x2a, 6}, {0x7, 5}, {0x2b, 6},
{0x76, 7}, {0x2c, 6}, {0x8, 5}, {0x9, 5}, {0x2d, 6}, {0x77, 7},
{0x78, 7}, {0x79, 7}, {0x7a, 7}, {0x7b, 7}, {0x0, 5}, {0x1, 5},
{0x2, 5}, {0x19, 6}, {0x1a, 6}, {0x1b, 6}, {0x1c, 6}, {0x1d, 6},
{0x1e, 6}, {0x1f, 6}, {0x7fb, 11}, {0x18, 6}};
static const uint8_t tail_xtra[3] = {0, 2, 3};
grpc_slice grpc_chttp2_base64_encode(grpc_slice input) {
size_t input_length = GRPC_SLICE_LENGTH(input);
size_t input_triplets = input_length / 3;
size_t tail_case = input_length % 3;
size_t output_length = input_triplets * 4 + tail_xtra[tail_case];
grpc_slice output = GRPC_SLICE_MALLOC(output_length);
uint8_t *in = GRPC_SLICE_START_PTR(input);
char *out = (char *)GRPC_SLICE_START_PTR(output);
size_t i;
/* encode full triplets */
for (i = 0; i < input_triplets; i++) {
out[0] = alphabet[in[0] >> 2];
out[1] = alphabet[((in[0] & 0x3) << 4) | (in[1] >> 4)];
out[2] = alphabet[((in[1] & 0xf) << 2) | (in[2] >> 6)];
out[3] = alphabet[in[2] & 0x3f];
out += 4;
in += 3;
}
/* encode the remaining bytes */
switch (tail_case) {
case 0:
break;
case 1:
out[0] = alphabet[in[0] >> 2];
out[1] = alphabet[(in[0] & 0x3) << 4];
out += 2;
in += 1;
break;
case 2:
out[0] = alphabet[in[0] >> 2];
out[1] = alphabet[((in[0] & 0x3) << 4) | (in[1] >> 4)];
out[2] = alphabet[(in[1] & 0xf) << 2];
out += 3;
in += 2;
break;
}
GPR_ASSERT(out == (char *)GRPC_SLICE_END_PTR(output));
GPR_ASSERT(in == GRPC_SLICE_END_PTR(input));
return output;
}
grpc_slice grpc_chttp2_huffman_compress(grpc_slice input) {
size_t nbits;
uint8_t *in;
uint8_t *out;
grpc_slice output;
uint32_t temp = 0;
uint32_t temp_length = 0;
nbits = 0;
for (in = GRPC_SLICE_START_PTR(input); in != GRPC_SLICE_END_PTR(input);
++in) {
nbits += grpc_chttp2_huffsyms[*in].length;
}
output = GRPC_SLICE_MALLOC(nbits / 8 + (nbits % 8 != 0));
out = GRPC_SLICE_START_PTR(output);
for (in = GRPC_SLICE_START_PTR(input); in != GRPC_SLICE_END_PTR(input);
++in) {
int sym = *in;
temp <<= grpc_chttp2_huffsyms[sym].length;
temp |= grpc_chttp2_huffsyms[sym].bits;
temp_length += grpc_chttp2_huffsyms[sym].length;
while (temp_length > 8) {
temp_length -= 8;
*out++ = (uint8_t)(temp >> temp_length);
}
}
if (temp_length) {
/* NB: the following integer arithmetic operation needs to be in its
* expanded form due to the "integral promotion" performed (see section
* 3.2.1.1 of the C89 draft standard). A cast to the smaller container type
* is then required to avoid the compiler warning */
*out++ = (uint8_t)((uint8_t)(temp << (8u - temp_length)) |
(uint8_t)(0xffu >> temp_length));
}
GPR_ASSERT(out == GRPC_SLICE_END_PTR(output));
return output;
}
typedef struct {
uint32_t temp;
uint32_t temp_length;
uint8_t *out;
} huff_out;
static void enc_flush_some(huff_out *out) {
while (out->temp_length > 8) {
out->temp_length -= 8;
*out->out++ = (uint8_t)(out->temp >> out->temp_length);
}
}
static void enc_add2(huff_out *out, uint8_t a, uint8_t b) {
b64_huff_sym sa = huff_alphabet[a];
b64_huff_sym sb = huff_alphabet[b];
out->temp = (out->temp << (sa.length + sb.length)) |
((uint32_t)sa.bits << sb.length) | sb.bits;
out->temp_length += (uint32_t)sa.length + (uint32_t)sb.length;
enc_flush_some(out);
}
static void enc_add1(huff_out *out, uint8_t a) {
b64_huff_sym sa = huff_alphabet[a];
out->temp = (out->temp << sa.length) | sa.bits;
out->temp_length += sa.length;
enc_flush_some(out);
}
grpc_slice grpc_chttp2_base64_encode_and_huffman_compress(grpc_slice input) {
size_t input_length = GRPC_SLICE_LENGTH(input);
size_t input_triplets = input_length / 3;
size_t tail_case = input_length % 3;
size_t output_syms = input_triplets * 4 + tail_xtra[tail_case];
size_t max_output_bits = 11 * output_syms;
size_t max_output_length = max_output_bits / 8 + (max_output_bits % 8 != 0);
grpc_slice output = GRPC_SLICE_MALLOC(max_output_length);
uint8_t *in = GRPC_SLICE_START_PTR(input);
uint8_t *start_out = GRPC_SLICE_START_PTR(output);
huff_out out;
size_t i;
out.temp = 0;
out.temp_length = 0;
out.out = start_out;
/* encode full triplets */
for (i = 0; i < input_triplets; i++) {
const uint8_t low_to_high = (uint8_t)((in[0] & 0x3) << 4);
const uint8_t high_to_low = in[1] >> 4;
enc_add2(&out, in[0] >> 2, low_to_high | high_to_low);
const uint8_t a = (uint8_t)((in[1] & 0xf) << 2);
const uint8_t b = (in[2] >> 6);
enc_add2(&out, a | b, in[2] & 0x3f);
in += 3;
}
/* encode the remaining bytes */
switch (tail_case) {
case 0:
break;
case 1:
enc_add2(&out, in[0] >> 2, (uint8_t)((in[0] & 0x3) << 4));
in += 1;
break;
case 2: {
const uint8_t low_to_high = (uint8_t)((in[0] & 0x3) << 4);
const uint8_t high_to_low = in[1] >> 4;
enc_add2(&out, in[0] >> 2, low_to_high | high_to_low);
enc_add1(&out, (uint8_t)((in[1] & 0xf) << 2));
in += 2;
break;
}
}
if (out.temp_length) {
/* NB: the following integer arithmetic operation needs to be in its
* expanded form due to the "integral promotion" performed (see section
* 3.2.1.1 of the C89 draft standard). A cast to the smaller container type
* is then required to avoid the compiler warning */
*out.out++ = (uint8_t)((uint8_t)(out.temp << (8u - out.temp_length)) |
(uint8_t)(0xffu >> out.temp_length));
}
GPR_ASSERT(out.out <= GRPC_SLICE_END_PTR(output));
GRPC_SLICE_SET_LENGTH(output, out.out - start_out);
GPR_ASSERT(in == GRPC_SLICE_END_PTR(input));
return output;
}
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