1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #include <grpc/support/port_platform.h>
20
21 #include "src/core/ext/transport/chttp2/transport/bin_encoder.h"
22
23 #include <string.h>
24
25 #include <grpc/support/log.h>
26 #include "src/core/ext/transport/chttp2/transport/huffsyms.h"
27
28 static const char alphabet[] =
29 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
30
31 typedef struct {
32 uint16_t bits;
33 uint8_t length;
34 } b64_huff_sym;
35
36 static const b64_huff_sym huff_alphabet[64] = {
37 {0x21, 6}, {0x5d, 7}, {0x5e, 7}, {0x5f, 7}, {0x60, 7}, {0x61, 7},
38 {0x62, 7}, {0x63, 7}, {0x64, 7}, {0x65, 7}, {0x66, 7}, {0x67, 7},
39 {0x68, 7}, {0x69, 7}, {0x6a, 7}, {0x6b, 7}, {0x6c, 7}, {0x6d, 7},
40 {0x6e, 7}, {0x6f, 7}, {0x70, 7}, {0x71, 7}, {0x72, 7}, {0xfc, 8},
41 {0x73, 7}, {0xfd, 8}, {0x3, 5}, {0x23, 6}, {0x4, 5}, {0x24, 6},
42 {0x5, 5}, {0x25, 6}, {0x26, 6}, {0x27, 6}, {0x6, 5}, {0x74, 7},
43 {0x75, 7}, {0x28, 6}, {0x29, 6}, {0x2a, 6}, {0x7, 5}, {0x2b, 6},
44 {0x76, 7}, {0x2c, 6}, {0x8, 5}, {0x9, 5}, {0x2d, 6}, {0x77, 7},
45 {0x78, 7}, {0x79, 7}, {0x7a, 7}, {0x7b, 7}, {0x0, 5}, {0x1, 5},
46 {0x2, 5}, {0x19, 6}, {0x1a, 6}, {0x1b, 6}, {0x1c, 6}, {0x1d, 6},
47 {0x1e, 6}, {0x1f, 6}, {0x7fb, 11}, {0x18, 6}};
48
49 static const uint8_t tail_xtra[3] = {0, 2, 3};
50
grpc_chttp2_base64_encode(grpc_slice input)51 grpc_slice grpc_chttp2_base64_encode(grpc_slice input) {
52 size_t input_length = GRPC_SLICE_LENGTH(input);
53 size_t input_triplets = input_length / 3;
54 size_t tail_case = input_length % 3;
55 size_t output_length = input_triplets * 4 + tail_xtra[tail_case];
56 grpc_slice output = GRPC_SLICE_MALLOC(output_length);
57 uint8_t* in = GRPC_SLICE_START_PTR(input);
58 char* out = reinterpret_cast<char*> GRPC_SLICE_START_PTR(output);
59 size_t i;
60
61 /* encode full triplets */
62 for (i = 0; i < input_triplets; i++) {
63 out[0] = alphabet[in[0] >> 2];
64 out[1] = alphabet[((in[0] & 0x3) << 4) | (in[1] >> 4)];
65 out[2] = alphabet[((in[1] & 0xf) << 2) | (in[2] >> 6)];
66 out[3] = alphabet[in[2] & 0x3f];
67 out += 4;
68 in += 3;
69 }
70
71 /* encode the remaining bytes */
72 switch (tail_case) {
73 case 0:
74 break;
75 case 1:
76 out[0] = alphabet[in[0] >> 2];
77 out[1] = alphabet[(in[0] & 0x3) << 4];
78 out += 2;
79 in += 1;
80 break;
81 case 2:
82 out[0] = alphabet[in[0] >> 2];
83 out[1] = alphabet[((in[0] & 0x3) << 4) | (in[1] >> 4)];
84 out[2] = alphabet[(in[1] & 0xf) << 2];
85 out += 3;
86 in += 2;
87 break;
88 }
89
90 GPR_ASSERT(out == (char*)GRPC_SLICE_END_PTR(output));
91 GPR_ASSERT(in == GRPC_SLICE_END_PTR(input));
92 return output;
93 }
94
grpc_chttp2_huffman_compress(grpc_slice input)95 grpc_slice grpc_chttp2_huffman_compress(grpc_slice input) {
96 size_t nbits;
97 uint8_t* in;
98 uint8_t* out;
99 grpc_slice output;
100 uint32_t temp = 0;
101 uint32_t temp_length = 0;
102
103 nbits = 0;
104 for (in = GRPC_SLICE_START_PTR(input); in != GRPC_SLICE_END_PTR(input);
105 ++in) {
106 nbits += grpc_chttp2_huffsyms[*in].length;
107 }
108
109 output = GRPC_SLICE_MALLOC(nbits / 8 + (nbits % 8 != 0));
110 out = GRPC_SLICE_START_PTR(output);
111 for (in = GRPC_SLICE_START_PTR(input); in != GRPC_SLICE_END_PTR(input);
112 ++in) {
113 int sym = *in;
114 temp <<= grpc_chttp2_huffsyms[sym].length;
115 temp |= grpc_chttp2_huffsyms[sym].bits;
116 temp_length += grpc_chttp2_huffsyms[sym].length;
117
118 while (temp_length > 8) {
119 temp_length -= 8;
120 *out++ = static_cast<uint8_t>(temp >> temp_length);
121 }
122 }
123
124 if (temp_length) {
125 /* NB: the following integer arithmetic operation needs to be in its
126 * expanded form due to the "integral promotion" performed (see section
127 * 3.2.1.1 of the C89 draft standard). A cast to the smaller container type
128 * is then required to avoid the compiler warning */
129 *out++ =
130 static_cast<uint8_t>(static_cast<uint8_t>(temp << (8u - temp_length)) |
131 static_cast<uint8_t>(0xffu >> temp_length));
132 }
133
134 GPR_ASSERT(out == GRPC_SLICE_END_PTR(output));
135
136 return output;
137 }
138
139 typedef struct {
140 uint32_t temp;
141 uint32_t temp_length;
142 uint8_t* out;
143 } huff_out;
144
enc_flush_some(huff_out * out)145 static void enc_flush_some(huff_out* out) {
146 while (out->temp_length > 8) {
147 out->temp_length -= 8;
148 *out->out++ = static_cast<uint8_t>(out->temp >> out->temp_length);
149 }
150 }
151
enc_add2(huff_out * out,uint8_t a,uint8_t b)152 static void enc_add2(huff_out* out, uint8_t a, uint8_t b) {
153 b64_huff_sym sa = huff_alphabet[a];
154 b64_huff_sym sb = huff_alphabet[b];
155 out->temp = (out->temp << (sa.length + sb.length)) |
156 (static_cast<uint32_t>(sa.bits) << sb.length) | sb.bits;
157 out->temp_length +=
158 static_cast<uint32_t>(sa.length) + static_cast<uint32_t>(sb.length);
159 enc_flush_some(out);
160 }
161
enc_add1(huff_out * out,uint8_t a)162 static void enc_add1(huff_out* out, uint8_t a) {
163 b64_huff_sym sa = huff_alphabet[a];
164 out->temp = (out->temp << sa.length) | sa.bits;
165 out->temp_length += sa.length;
166 enc_flush_some(out);
167 }
168
grpc_chttp2_base64_encode_and_huffman_compress(grpc_slice input)169 grpc_slice grpc_chttp2_base64_encode_and_huffman_compress(grpc_slice input) {
170 size_t input_length = GRPC_SLICE_LENGTH(input);
171 size_t input_triplets = input_length / 3;
172 size_t tail_case = input_length % 3;
173 size_t output_syms = input_triplets * 4 + tail_xtra[tail_case];
174 size_t max_output_bits = 11 * output_syms;
175 size_t max_output_length = max_output_bits / 8 + (max_output_bits % 8 != 0);
176 grpc_slice output = GRPC_SLICE_MALLOC(max_output_length);
177 uint8_t* in = GRPC_SLICE_START_PTR(input);
178 uint8_t* start_out = GRPC_SLICE_START_PTR(output);
179 huff_out out;
180 size_t i;
181
182 out.temp = 0;
183 out.temp_length = 0;
184 out.out = start_out;
185
186 /* encode full triplets */
187 for (i = 0; i < input_triplets; i++) {
188 const uint8_t low_to_high = static_cast<uint8_t>((in[0] & 0x3) << 4);
189 const uint8_t high_to_low = in[1] >> 4;
190 enc_add2(&out, in[0] >> 2, low_to_high | high_to_low);
191
192 const uint8_t a = static_cast<uint8_t>((in[1] & 0xf) << 2);
193 const uint8_t b = (in[2] >> 6);
194 enc_add2(&out, a | b, in[2] & 0x3f);
195 in += 3;
196 }
197
198 /* encode the remaining bytes */
199 switch (tail_case) {
200 case 0:
201 break;
202 case 1:
203 enc_add2(&out, in[0] >> 2, static_cast<uint8_t>((in[0] & 0x3) << 4));
204 in += 1;
205 break;
206 case 2: {
207 const uint8_t low_to_high = static_cast<uint8_t>((in[0] & 0x3) << 4);
208 const uint8_t high_to_low = in[1] >> 4;
209 enc_add2(&out, in[0] >> 2, low_to_high | high_to_low);
210 enc_add1(&out, static_cast<uint8_t>((in[1] & 0xf) << 2));
211 in += 2;
212 break;
213 }
214 }
215
216 if (out.temp_length) {
217 /* NB: the following integer arithmetic operation needs to be in its
218 * expanded form due to the "integral promotion" performed (see section
219 * 3.2.1.1 of the C89 draft standard). A cast to the smaller container type
220 * is then required to avoid the compiler warning */
221 *out.out++ = static_cast<uint8_t>(
222 static_cast<uint8_t>(out.temp << (8u - out.temp_length)) |
223 static_cast<uint8_t>(0xffu >> out.temp_length));
224 }
225
226 GPR_ASSERT(out.out <= GRPC_SLICE_END_PTR(output));
227 GRPC_SLICE_SET_LENGTH(output, out.out - start_out);
228
229 GPR_ASSERT(in == GRPC_SLICE_END_PTR(input));
230 return output;
231 }
232