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| 1 | |
| 2 //********************************************************************* | |
| 3 //* Base64 - a simple base64 encoder and decoder. | |
| 4 //* | |
| 5 //* Copyright (c) 1999, Bob Withers - bwit@pobox.com | |
| 6 //* | |
| 7 //* This code may be freely used for any purpose, either personal | |
| 8 //* or commercial, provided the authors copyright notice remains | |
| 9 //* intact. | |
| 10 //* | |
| 11 //* Enhancements by Stanley Yamane: | |
| 12 //* o reverse lookup table for the decode function | |
| 13 //* o reserve string buffer space in advance | |
| 14 //* | |
| 15 //********************************************************************* | |
| 16 | |
| 17 #include "webrtc/base/base64.h" | |
| 18 | |
| 19 #include <string.h> | |
| 20 | |
| 21 #include "webrtc/base/checks.h" | |
| 22 | |
| 23 using std::vector; | |
| 24 | |
| 25 namespace rtc { | |
| 26 | |
| 27 static const char kPad = '='; | |
| 28 static const unsigned char pd = 0xFD; // Padding | |
| 29 static const unsigned char sp = 0xFE; // Whitespace | |
| 30 static const unsigned char il = 0xFF; // Illegal base64 character | |
| 31 | |
| 32 const char Base64::Base64Table[] = | |
| 33 // 0000000000111111111122222222223333333333444444444455555555556666 | |
| 34 // 0123456789012345678901234567890123456789012345678901234567890123 | |
| 35 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; | |
| 36 | |
| 37 // Decode Table gives the index of any valid base64 character in the | |
| 38 // Base64 table | |
| 39 // 65 == A, 97 == a, 48 == 0, 43 == +, 47 == / | |
| 40 | |
| 41 const unsigned char Base64::DecodeTable[] = { | |
| 42 // 0 1 2 3 4 5 6 7 8 9 | |
| 43 il, il, il, il, il, il, il, il, il, sp, // 0 - 9 | |
| 44 sp, sp, sp, sp, il, il, il, il, il, il, // 10 - 19 | |
| 45 il, il, il, il, il, il, il, il, il, il, // 20 - 29 | |
| 46 il, il, sp, il, il, il, il, il, il, il, // 30 - 39 | |
| 47 il, il, il, 62, il, il, il, 63, 52, 53, // 40 - 49 | |
| 48 54, 55, 56, 57, 58, 59, 60, 61, il, il, // 50 - 59 | |
| 49 il, pd, il, il, il, 0, 1, 2, 3, 4, // 60 - 69 | |
| 50 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 70 - 79 | |
| 51 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 80 - 89 | |
| 52 25, il, il, il, il, il, il, 26, 27, 28, // 90 - 99 | |
| 53 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // 100 - 109 | |
| 54 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, // 110 - 119 | |
| 55 49, 50, 51, il, il, il, il, il, il, il, // 120 - 129 | |
| 56 il, il, il, il, il, il, il, il, il, il, // 130 - 139 | |
| 57 il, il, il, il, il, il, il, il, il, il, // 140 - 149 | |
| 58 il, il, il, il, il, il, il, il, il, il, // 150 - 159 | |
| 59 il, il, il, il, il, il, il, il, il, il, // 160 - 169 | |
| 60 il, il, il, il, il, il, il, il, il, il, // 170 - 179 | |
| 61 il, il, il, il, il, il, il, il, il, il, // 180 - 189 | |
| 62 il, il, il, il, il, il, il, il, il, il, // 190 - 199 | |
| 63 il, il, il, il, il, il, il, il, il, il, // 200 - 209 | |
| 64 il, il, il, il, il, il, il, il, il, il, // 210 - 219 | |
| 65 il, il, il, il, il, il, il, il, il, il, // 220 - 229 | |
| 66 il, il, il, il, il, il, il, il, il, il, // 230 - 239 | |
| 67 il, il, il, il, il, il, il, il, il, il, // 240 - 249 | |
| 68 il, il, il, il, il, il // 250 - 255 | |
| 69 }; | |
| 70 | |
| 71 bool Base64::IsBase64Char(char ch) { | |
| 72 return (('A' <= ch) && (ch <= 'Z')) || (('a' <= ch) && (ch <= 'z')) || | |
| 73 (('0' <= ch) && (ch <= '9')) || (ch == '+') || (ch == '/'); | |
| 74 } | |
| 75 | |
| 76 bool Base64::GetNextBase64Char(char ch, char* next_ch) { | |
| 77 if (next_ch == nullptr) { | |
| 78 return false; | |
| 79 } | |
| 80 const char* p = strchr(Base64Table, ch); | |
| 81 if (!p) | |
| 82 return false; | |
| 83 ++p; | |
| 84 *next_ch = (*p) ? *p : Base64Table[0]; | |
| 85 return true; | |
| 86 } | |
| 87 | |
| 88 bool Base64::IsBase64Encoded(const std::string& str) { | |
| 89 for (size_t i = 0; i < str.size(); ++i) { | |
| 90 if (!IsBase64Char(str.at(i))) | |
| 91 return false; | |
| 92 } | |
| 93 return true; | |
| 94 } | |
| 95 | |
| 96 void Base64::EncodeFromArray(const void* data, | |
| 97 size_t len, | |
| 98 std::string* result) { | |
| 99 RTC_DCHECK(nullptr != result); | |
| 100 result->clear(); | |
| 101 result->resize(((len + 2) / 3) * 4); | |
| 102 const unsigned char* byte_data = static_cast<const unsigned char*>(data); | |
| 103 | |
| 104 unsigned char c; | |
| 105 size_t i = 0; | |
| 106 size_t dest_ix = 0; | |
| 107 while (i < len) { | |
| 108 c = (byte_data[i] >> 2) & 0x3f; | |
| 109 (*result)[dest_ix++] = Base64Table[c]; | |
| 110 | |
| 111 c = (byte_data[i] << 4) & 0x3f; | |
| 112 if (++i < len) { | |
| 113 c |= (byte_data[i] >> 4) & 0x0f; | |
| 114 } | |
| 115 (*result)[dest_ix++] = Base64Table[c]; | |
| 116 | |
| 117 if (i < len) { | |
| 118 c = (byte_data[i] << 2) & 0x3f; | |
| 119 if (++i < len) { | |
| 120 c |= (byte_data[i] >> 6) & 0x03; | |
| 121 } | |
| 122 (*result)[dest_ix++] = Base64Table[c]; | |
| 123 } else { | |
| 124 (*result)[dest_ix++] = kPad; | |
| 125 } | |
| 126 | |
| 127 if (i < len) { | |
| 128 c = byte_data[i] & 0x3f; | |
| 129 (*result)[dest_ix++] = Base64Table[c]; | |
| 130 ++i; | |
| 131 } else { | |
| 132 (*result)[dest_ix++] = kPad; | |
| 133 } | |
| 134 } | |
| 135 } | |
| 136 | |
| 137 size_t Base64::GetNextQuantum(DecodeFlags parse_flags, | |
| 138 bool illegal_pads, | |
| 139 const char* data, | |
| 140 size_t len, | |
| 141 size_t* dpos, | |
| 142 unsigned char qbuf[4], | |
| 143 bool* padded) { | |
| 144 size_t byte_len = 0, pad_len = 0, pad_start = 0; | |
| 145 for (; (byte_len < 4) && (*dpos < len); ++*dpos) { | |
| 146 qbuf[byte_len] = DecodeTable[static_cast<unsigned char>(data[*dpos])]; | |
| 147 if ((il == qbuf[byte_len]) || (illegal_pads && (pd == qbuf[byte_len]))) { | |
| 148 if (parse_flags != DO_PARSE_ANY) | |
| 149 break; | |
| 150 // Ignore illegal characters | |
| 151 } else if (sp == qbuf[byte_len]) { | |
| 152 if (parse_flags == DO_PARSE_STRICT) | |
| 153 break; | |
| 154 // Ignore spaces | |
| 155 } else if (pd == qbuf[byte_len]) { | |
| 156 if (byte_len < 2) { | |
| 157 if (parse_flags != DO_PARSE_ANY) | |
| 158 break; | |
| 159 // Ignore unexpected padding | |
| 160 } else if (byte_len + pad_len >= 4) { | |
| 161 if (parse_flags != DO_PARSE_ANY) | |
| 162 break; | |
| 163 // Ignore extra pads | |
| 164 } else { | |
| 165 if (1 == ++pad_len) { | |
| 166 pad_start = *dpos; | |
| 167 } | |
| 168 } | |
| 169 } else { | |
| 170 if (pad_len > 0) { | |
| 171 if (parse_flags != DO_PARSE_ANY) | |
| 172 break; | |
| 173 // Ignore pads which are followed by data | |
| 174 pad_len = 0; | |
| 175 } | |
| 176 ++byte_len; | |
| 177 } | |
| 178 } | |
| 179 for (size_t i = byte_len; i < 4; ++i) { | |
| 180 qbuf[i] = 0; | |
| 181 } | |
| 182 if (4 == byte_len + pad_len) { | |
| 183 *padded = true; | |
| 184 } else { | |
| 185 *padded = false; | |
| 186 if (pad_len) { | |
| 187 // Roll back illegal padding | |
| 188 *dpos = pad_start; | |
| 189 } | |
| 190 } | |
| 191 return byte_len; | |
| 192 } | |
| 193 | |
| 194 bool Base64::DecodeFromArray(const char* data, | |
| 195 size_t len, | |
| 196 DecodeFlags flags, | |
| 197 std::string* result, | |
| 198 size_t* data_used) { | |
| 199 return DecodeFromArrayTemplate<std::string>(data, len, flags, result, | |
| 200 data_used); | |
| 201 } | |
| 202 | |
| 203 bool Base64::DecodeFromArray(const char* data, | |
| 204 size_t len, | |
| 205 DecodeFlags flags, | |
| 206 vector<char>* result, | |
| 207 size_t* data_used) { | |
| 208 return DecodeFromArrayTemplate<vector<char>>(data, len, flags, result, | |
| 209 data_used); | |
| 210 } | |
| 211 | |
| 212 bool Base64::DecodeFromArray(const char* data, | |
| 213 size_t len, | |
| 214 DecodeFlags flags, | |
| 215 vector<uint8_t>* result, | |
| 216 size_t* data_used) { | |
| 217 return DecodeFromArrayTemplate<vector<uint8_t>>(data, len, flags, result, | |
| 218 data_used); | |
| 219 } | |
| 220 | |
| 221 template <typename T> | |
| 222 bool Base64::DecodeFromArrayTemplate(const char* data, | |
| 223 size_t len, | |
| 224 DecodeFlags flags, | |
| 225 T* result, | |
| 226 size_t* data_used) { | |
| 227 RTC_DCHECK(nullptr != result); | |
| 228 RTC_DCHECK(flags <= (DO_PARSE_MASK | DO_PAD_MASK | DO_TERM_MASK)); | |
| 229 | |
| 230 const DecodeFlags parse_flags = flags & DO_PARSE_MASK; | |
| 231 const DecodeFlags pad_flags = flags & DO_PAD_MASK; | |
| 232 const DecodeFlags term_flags = flags & DO_TERM_MASK; | |
| 233 RTC_DCHECK(0 != parse_flags); | |
| 234 RTC_DCHECK(0 != pad_flags); | |
| 235 RTC_DCHECK(0 != term_flags); | |
| 236 | |
| 237 result->clear(); | |
| 238 result->reserve(len); | |
| 239 | |
| 240 size_t dpos = 0; | |
| 241 bool success = true, padded; | |
| 242 unsigned char c, qbuf[4]; | |
| 243 while (dpos < len) { | |
| 244 size_t qlen = GetNextQuantum(parse_flags, (DO_PAD_NO == pad_flags), data, | |
| 245 len, &dpos, qbuf, &padded); | |
| 246 c = (qbuf[0] << 2) | ((qbuf[1] >> 4) & 0x3); | |
| 247 if (qlen >= 2) { | |
| 248 result->push_back(c); | |
| 249 c = ((qbuf[1] << 4) & 0xf0) | ((qbuf[2] >> 2) & 0xf); | |
| 250 if (qlen >= 3) { | |
| 251 result->push_back(c); | |
| 252 c = ((qbuf[2] << 6) & 0xc0) | qbuf[3]; | |
| 253 if (qlen >= 4) { | |
| 254 result->push_back(c); | |
| 255 c = 0; | |
| 256 } | |
| 257 } | |
| 258 } | |
| 259 if (qlen < 4) { | |
| 260 if ((DO_TERM_ANY != term_flags) && (0 != c)) { | |
| 261 success = false; // unused bits | |
| 262 } | |
| 263 if ((DO_PAD_YES == pad_flags) && !padded) { | |
| 264 success = false; // expected padding | |
| 265 } | |
| 266 break; | |
| 267 } | |
| 268 } | |
| 269 if ((DO_TERM_BUFFER == term_flags) && (dpos != len)) { | |
| 270 success = false; // unused chars | |
| 271 } | |
| 272 if (data_used) { | |
| 273 *data_used = dpos; | |
| 274 } | |
| 275 return success; | |
| 276 } | |
| 277 | |
| 278 } // namespace rtc | |
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