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/lib/slice/b64.h"
22
23 #include <stdint.h>
24 #include <string.h>
25
26 #include <grpc/support/alloc.h>
27 #include <grpc/support/log.h>
28
29 #include "src/core/lib/gpr/useful.h"
30 #include "src/core/lib/slice/slice_internal.h"
31
32 /* --- Constants. --- */
33
34 static const int8_t base64_bytes[] = {
35 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
36 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
37 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
38 -1, -1, -1, -1, -1, -1, -1, 0x3E, -1, -1, -1, 0x3F,
39 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, -1, -1,
40 -1, 0x7F, -1, -1, -1, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
41 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12,
42 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, -1, -1, -1, -1, -1,
43 -1, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
44 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30,
45 0x31, 0x32, 0x33, -1, -1, -1, -1, -1};
46
47 static const char base64_url_unsafe_chars[] =
48 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
49 static const char base64_url_safe_chars[] =
50 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
51
52 #define GRPC_BASE64_PAD_CHAR '='
53 #define GRPC_BASE64_PAD_BYTE 0x7F
54 #define GRPC_BASE64_MULTILINE_LINE_LEN 76
55 #define GRPC_BASE64_MULTILINE_NUM_BLOCKS (GRPC_BASE64_MULTILINE_LINE_LEN / 4)
56
57 /* --- base64 functions. --- */
58
grpc_base64_encode(const void * vdata,size_t data_size,int url_safe,int multiline)59 char* grpc_base64_encode(const void* vdata, size_t data_size, int url_safe,
60 int multiline) {
61 size_t result_projected_size =
62 grpc_base64_estimate_encoded_size(data_size, url_safe, multiline);
63 char* result = static_cast<char*>(gpr_malloc(result_projected_size));
64 grpc_base64_encode_core(result, vdata, data_size, url_safe, multiline);
65 return result;
66 }
67
grpc_base64_estimate_encoded_size(size_t data_size,int url_safe,int multiline)68 size_t grpc_base64_estimate_encoded_size(size_t data_size, int url_safe,
69 int multiline) {
70 size_t result_projected_size =
71 4 * ((data_size + 3) / 3) +
72 2 * (multiline ? (data_size / (3 * GRPC_BASE64_MULTILINE_NUM_BLOCKS))
73 : 0) +
74 1;
75 return result_projected_size;
76 }
77
grpc_base64_encode_core(char * result,const void * vdata,size_t data_size,int url_safe,int multiline)78 void grpc_base64_encode_core(char* result, const void* vdata, size_t data_size,
79 int url_safe, int multiline) {
80 const unsigned char* data = static_cast<const unsigned char*>(vdata);
81 const char* base64_chars =
82 url_safe ? base64_url_safe_chars : base64_url_unsafe_chars;
83 const size_t result_projected_size =
84 grpc_base64_estimate_encoded_size(data_size, url_safe, multiline);
85
86 char* current = result;
87 size_t num_blocks = 0;
88 size_t i = 0;
89
90 /* Encode each block. */
91 while (data_size >= 3) {
92 *current++ = base64_chars[(data[i] >> 2) & 0x3F];
93 *current++ =
94 base64_chars[((data[i] & 0x03) << 4) | ((data[i + 1] >> 4) & 0x0F)];
95 *current++ =
96 base64_chars[((data[i + 1] & 0x0F) << 2) | ((data[i + 2] >> 6) & 0x03)];
97 *current++ = base64_chars[data[i + 2] & 0x3F];
98
99 data_size -= 3;
100 i += 3;
101 if (multiline && (++num_blocks == GRPC_BASE64_MULTILINE_NUM_BLOCKS)) {
102 *current++ = '\r';
103 *current++ = '\n';
104 num_blocks = 0;
105 }
106 }
107
108 /* Take care of the tail. */
109 if (data_size == 2) {
110 *current++ = base64_chars[(data[i] >> 2) & 0x3F];
111 *current++ =
112 base64_chars[((data[i] & 0x03) << 4) | ((data[i + 1] >> 4) & 0x0F)];
113 *current++ = base64_chars[(data[i + 1] & 0x0F) << 2];
114 *current++ = GRPC_BASE64_PAD_CHAR;
115 } else if (data_size == 1) {
116 *current++ = base64_chars[(data[i] >> 2) & 0x3F];
117 *current++ = base64_chars[(data[i] & 0x03) << 4];
118 *current++ = GRPC_BASE64_PAD_CHAR;
119 *current++ = GRPC_BASE64_PAD_CHAR;
120 }
121
122 GPR_ASSERT(current >= result);
123 GPR_ASSERT((uintptr_t)(current - result) < result_projected_size);
124 result[current - result] = '\0';
125 }
126
grpc_base64_decode(const char * b64,int url_safe)127 grpc_slice grpc_base64_decode(const char* b64, int url_safe) {
128 return grpc_base64_decode_with_len(b64, strlen(b64), url_safe);
129 }
130
decode_one_char(const unsigned char * codes,unsigned char * result,size_t * result_offset)131 static void decode_one_char(const unsigned char* codes, unsigned char* result,
132 size_t* result_offset) {
133 uint32_t packed = (static_cast<uint32_t>(codes[0]) << 2) |
134 (static_cast<uint32_t>(codes[1]) >> 4);
135 result[(*result_offset)++] = static_cast<unsigned char>(packed);
136 }
137
decode_two_chars(const unsigned char * codes,unsigned char * result,size_t * result_offset)138 static void decode_two_chars(const unsigned char* codes, unsigned char* result,
139 size_t* result_offset) {
140 uint32_t packed = (static_cast<uint32_t>(codes[0]) << 10) |
141 (static_cast<uint32_t>(codes[1]) << 4) |
142 (static_cast<uint32_t>(codes[2]) >> 2);
143 result[(*result_offset)++] = static_cast<unsigned char>(packed >> 8);
144 result[(*result_offset)++] = static_cast<unsigned char>(packed);
145 }
146
decode_group(const unsigned char * codes,size_t num_codes,unsigned char * result,size_t * result_offset)147 static int decode_group(const unsigned char* codes, size_t num_codes,
148 unsigned char* result, size_t* result_offset) {
149 GPR_ASSERT(num_codes <= 4);
150
151 /* Short end groups that may not have padding. */
152 if (num_codes == 1) {
153 gpr_log(GPR_ERROR, "Invalid group. Must be at least 2 bytes.");
154 return 0;
155 }
156 if (num_codes == 2) {
157 decode_one_char(codes, result, result_offset);
158 return 1;
159 }
160 if (num_codes == 3) {
161 decode_two_chars(codes, result, result_offset);
162 return 1;
163 }
164
165 /* Regular 4 byte groups with padding or not. */
166 GPR_ASSERT(num_codes == 4);
167 if (codes[0] == GRPC_BASE64_PAD_BYTE || codes[1] == GRPC_BASE64_PAD_BYTE) {
168 gpr_log(GPR_ERROR, "Invalid padding detected.");
169 return 0;
170 }
171 if (codes[2] == GRPC_BASE64_PAD_BYTE) {
172 if (codes[3] == GRPC_BASE64_PAD_BYTE) {
173 decode_one_char(codes, result, result_offset);
174 } else {
175 gpr_log(GPR_ERROR, "Invalid padding detected.");
176 return 0;
177 }
178 } else if (codes[3] == GRPC_BASE64_PAD_BYTE) {
179 decode_two_chars(codes, result, result_offset);
180 } else {
181 /* No padding. */
182 uint32_t packed = (static_cast<uint32_t>(codes[0]) << 18) |
183 (static_cast<uint32_t>(codes[1]) << 12) |
184 (static_cast<uint32_t>(codes[2]) << 6) | codes[3];
185 result[(*result_offset)++] = static_cast<unsigned char>(packed >> 16);
186 result[(*result_offset)++] = static_cast<unsigned char>(packed >> 8);
187 result[(*result_offset)++] = static_cast<unsigned char>(packed);
188 }
189 return 1;
190 }
191
grpc_base64_decode_with_len(const char * b64,size_t b64_len,int url_safe)192 grpc_slice grpc_base64_decode_with_len(const char* b64, size_t b64_len,
193 int url_safe) {
194 grpc_slice result = GRPC_SLICE_MALLOC(b64_len);
195 unsigned char* current = GRPC_SLICE_START_PTR(result);
196 size_t result_size = 0;
197 unsigned char codes[4];
198 size_t num_codes = 0;
199
200 while (b64_len--) {
201 unsigned char c = static_cast<unsigned char>(*b64++);
202 signed char code;
203 if (c >= GPR_ARRAY_SIZE(base64_bytes)) continue;
204 if (url_safe) {
205 if (c == '+' || c == '/') {
206 gpr_log(GPR_ERROR, "Invalid character for url safe base64 %c", c);
207 goto fail;
208 }
209 if (c == '-') {
210 c = '+';
211 } else if (c == '_') {
212 c = '/';
213 }
214 }
215 code = base64_bytes[c];
216 if (code == -1) {
217 if (c != '\r' && c != '\n') {
218 gpr_log(GPR_ERROR, "Invalid character %c", c);
219 goto fail;
220 }
221 } else {
222 codes[num_codes++] = static_cast<unsigned char>(code);
223 if (num_codes == 4) {
224 if (!decode_group(codes, num_codes, current, &result_size)) goto fail;
225 num_codes = 0;
226 }
227 }
228 }
229
230 if (num_codes != 0 &&
231 !decode_group(codes, num_codes, current, &result_size)) {
232 goto fail;
233 }
234 GRPC_SLICE_SET_LENGTH(result, result_size);
235 return result;
236
237 fail:
238 grpc_slice_unref_internal(result);
239 return grpc_empty_slice();
240 }
241