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