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/*
*
* Copyright 2016 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_decoder.h"
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include "src/core/lib/slice/slice_internal.h"
#include "src/core/lib/slice/slice_string_helpers.h"
#include "src/core/lib/support/string.h"
static uint8_t decode_table[] = {
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 62, 0x40, 0x40, 0x40, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40};
static const uint8_t tail_xtra[4] = {0, 0, 1, 2};
static bool input_is_valid(uint8_t* input_ptr, size_t length) {
size_t i;
for (i = 0; i < length; ++i) {
if ((decode_table[input_ptr[i]] & 0xC0) != 0) {
gpr_log(GPR_ERROR,
"Base64 decoding failed, invalid character '%c' in base64 "
"input.\n",
(char)(*input_ptr));
return false;
}
}
return true;
}
#define COMPOSE_OUTPUT_BYTE_0(input_ptr) \
(uint8_t)((decode_table[input_ptr[0]] << 2) | \
(decode_table[input_ptr[1]] >> 4))
#define COMPOSE_OUTPUT_BYTE_1(input_ptr) \
(uint8_t)((decode_table[input_ptr[1]] << 4) | \
(decode_table[input_ptr[2]] >> 2))
#define COMPOSE_OUTPUT_BYTE_2(input_ptr) \
(uint8_t)((decode_table[input_ptr[2]] << 6) | decode_table[input_ptr[3]])
bool grpc_base64_decode_partial(struct grpc_base64_decode_context* ctx) {
size_t input_tail;
if (ctx->input_cur > ctx->input_end || ctx->output_cur > ctx->output_end) {
return false;
}
// Process a block of 4 input characters and 3 output bytes
while (ctx->input_end >= ctx->input_cur + 4 &&
ctx->output_end >= ctx->output_cur + 3) {
if (!input_is_valid(ctx->input_cur, 4)) return false;
ctx->output_cur[0] = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
ctx->output_cur[1] = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
ctx->output_cur[2] = COMPOSE_OUTPUT_BYTE_2(ctx->input_cur);
ctx->output_cur += 3;
ctx->input_cur += 4;
}
// Process the tail of input data
input_tail = (size_t)(ctx->input_end - ctx->input_cur);
if (input_tail == 4) {
// Process the input data with pad chars
if (ctx->input_cur[3] == '=') {
if (ctx->input_cur[2] == '=' && ctx->output_end >= ctx->output_cur + 1) {
if (!input_is_valid(ctx->input_cur, 2)) return false;
*(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
ctx->input_cur += 4;
} else if (ctx->output_end >= ctx->output_cur + 2) {
if (!input_is_valid(ctx->input_cur, 3)) return false;
*(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
*(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
;
ctx->input_cur += 4;
}
}
} else if (ctx->contains_tail && input_tail > 1) {
// Process the input data without pad chars, but constains_tail is set
if (ctx->output_end >= ctx->output_cur + tail_xtra[input_tail]) {
if (!input_is_valid(ctx->input_cur, input_tail)) return false;
switch (input_tail) {
case 3:
ctx->output_cur[1] = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
/* fallthrough */
case 2:
ctx->output_cur[0] = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
}
ctx->output_cur += tail_xtra[input_tail];
ctx->input_cur += input_tail;
}
}
return true;
}
grpc_slice grpc_chttp2_base64_decode(grpc_slice input) {
size_t input_length = GRPC_SLICE_LENGTH(input);
size_t output_length = input_length / 4 * 3;
struct grpc_base64_decode_context ctx;
grpc_slice output;
if (input_length % 4 != 0) {
gpr_log(GPR_ERROR,
"Base64 decoding failed, input of "
"grpc_chttp2_base64_decode has a length of %d, which is not a "
"multiple of 4.\n",
(int)input_length);
return grpc_empty_slice();
}
if (input_length > 0) {
uint8_t* input_end = GRPC_SLICE_END_PTR(input);
if (*(--input_end) == '=') {
output_length--;
if (*(--input_end) == '=') {
output_length--;
}
}
}
output = GRPC_SLICE_MALLOC(output_length);
ctx.input_cur = GRPC_SLICE_START_PTR(input);
ctx.input_end = GRPC_SLICE_END_PTR(input);
ctx.output_cur = GRPC_SLICE_START_PTR(output);
ctx.output_end = GRPC_SLICE_END_PTR(output);
ctx.contains_tail = false;
if (!grpc_base64_decode_partial(&ctx)) {
char* s = grpc_slice_to_c_string(input);
gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
gpr_free(s);
grpc_slice_unref_internal(output);
return grpc_empty_slice();
}
GPR_ASSERT(ctx.output_cur == GRPC_SLICE_END_PTR(output));
GPR_ASSERT(ctx.input_cur == GRPC_SLICE_END_PTR(input));
return output;
}
grpc_slice grpc_chttp2_base64_decode_with_length(grpc_slice input,
size_t output_length) {
size_t input_length = GRPC_SLICE_LENGTH(input);
grpc_slice output = GRPC_SLICE_MALLOC(output_length);
struct grpc_base64_decode_context ctx;
// The length of a base64 string cannot be 4 * n + 1
if (input_length % 4 == 1) {
gpr_log(GPR_ERROR,
"Base64 decoding failed, input of "
"grpc_chttp2_base64_decode_with_length has a length of %d, which "
"has a tail of 1 byte.\n",
(int)input_length);
grpc_slice_unref_internal(output);
return grpc_empty_slice();
}
if (output_length > input_length / 4 * 3 + tail_xtra[input_length % 4]) {
gpr_log(GPR_ERROR,
"Base64 decoding failed, output_length %d is longer "
"than the max possible output length %d.\n",
(int)output_length,
(int)(input_length / 4 * 3 + tail_xtra[input_length % 4]));
grpc_slice_unref_internal(output);
return grpc_empty_slice();
}
ctx.input_cur = GRPC_SLICE_START_PTR(input);
ctx.input_end = GRPC_SLICE_END_PTR(input);
ctx.output_cur = GRPC_SLICE_START_PTR(output);
ctx.output_end = GRPC_SLICE_END_PTR(output);
ctx.contains_tail = true;
if (!grpc_base64_decode_partial(&ctx)) {
char* s = grpc_slice_to_c_string(input);
gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
gpr_free(s);
grpc_slice_unref_internal(output);
return grpc_empty_slice();
}
GPR_ASSERT(ctx.output_cur == GRPC_SLICE_END_PTR(output));
GPR_ASSERT(ctx.input_cur <= GRPC_SLICE_END_PTR(input));
return output;
}
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