1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24
25 /* Base64 encoding/decoding */
26
27 #include "curl_setup.h"
28
29 #if !defined(CURL_DISABLE_HTTP_AUTH) || defined(USE_SSH) || \
30 !defined(CURL_DISABLE_LDAP) || \
31 !defined(CURL_DISABLE_SMTP) || \
32 !defined(CURL_DISABLE_POP3) || \
33 !defined(CURL_DISABLE_IMAP) || \
34 !defined(CURL_DISABLE_DIGEST_AUTH) || \
35 !defined(CURL_DISABLE_DOH) || defined(USE_SSL) || defined(BUILDING_CURL)
36 #include "curl/curl.h"
37 #include "warnless.h"
38 #include "curl_base64.h"
39
40 /* The last 2 #include files should be in this order */
41 #ifdef BUILDING_LIBCURL
42 #include "curl_memory.h"
43 #endif
44 #include "memdebug.h"
45
46 /* ---- Base64 Encoding/Decoding Table --- */
47 /* Padding character string starts at offset 64. */
48 static const char base64encdec[]=
49 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
50
51 /* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648
52 section 5 */
53 static const char base64url[]=
54 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
55
56 static const unsigned char decodetable[] =
57 { 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255,
58 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
59 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28,
60 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
61 48, 49, 50, 51 };
62 /*
63 * Curl_base64_decode()
64 *
65 * Given a base64 NUL-terminated string at src, decode it and return a
66 * pointer in *outptr to a newly allocated memory area holding decoded
67 * data. Size of decoded data is returned in variable pointed by outlen.
68 *
69 * Returns CURLE_OK on success, otherwise specific error code. Function
70 * output shall not be considered valid unless CURLE_OK is returned.
71 *
72 * When decoded data length is 0, returns NULL in *outptr.
73 *
74 * @unittest: 1302
75 */
Curl_base64_decode(const char * src,unsigned char ** outptr,size_t * outlen)76 CURLcode Curl_base64_decode(const char *src,
77 unsigned char **outptr, size_t *outlen)
78 {
79 size_t srclen = 0;
80 size_t padding = 0;
81 size_t i;
82 size_t numQuantums;
83 size_t fullQuantums;
84 size_t rawlen = 0;
85 unsigned char *pos;
86 unsigned char *newstr;
87 unsigned char lookup[256];
88
89 *outptr = NULL;
90 *outlen = 0;
91 srclen = strlen(src);
92
93 /* Check the length of the input string is valid */
94 if(!srclen || srclen % 4)
95 return CURLE_BAD_CONTENT_ENCODING;
96
97 /* srclen is at least 4 here */
98 while(src[srclen - 1 - padding] == '=') {
99 /* count padding characters */
100 padding++;
101 /* A maximum of two = padding characters is allowed */
102 if(padding > 2)
103 return CURLE_BAD_CONTENT_ENCODING;
104 }
105
106 /* Calculate the number of quantums */
107 numQuantums = srclen / 4;
108 fullQuantums = numQuantums - (padding ? 1 : 0);
109
110 /* Calculate the size of the decoded string */
111 rawlen = (numQuantums * 3) - padding;
112
113 /* Allocate our buffer including room for a null-terminator */
114 newstr = malloc(rawlen + 1);
115 if(!newstr)
116 return CURLE_OUT_OF_MEMORY;
117
118 pos = newstr;
119
120 memset(lookup, 0xff, sizeof(lookup));
121 memcpy(&lookup['+'], decodetable, sizeof(decodetable));
122 /* replaces
123 {
124 unsigned char c;
125 const unsigned char *p = (const unsigned char *)base64encdec;
126 for(c = 0; *p; c++, p++)
127 lookup[*p] = c;
128 }
129 */
130
131 /* Decode the complete quantums first */
132 for(i = 0; i < fullQuantums; i++) {
133 unsigned char val;
134 unsigned int x = 0;
135 int j;
136
137 for(j = 0; j < 4; j++) {
138 val = lookup[(unsigned char)*src++];
139 if(val == 0xff) /* bad symbol */
140 goto bad;
141 x = (x << 6) | val;
142 }
143 pos[2] = x & 0xff;
144 pos[1] = (x >> 8) & 0xff;
145 pos[0] = (x >> 16) & 0xff;
146 pos += 3;
147 }
148 if(padding) {
149 /* this means either 8 or 16 bits output */
150 unsigned char val;
151 unsigned int x = 0;
152 int j;
153 size_t padc = 0;
154 for(j = 0; j < 4; j++) {
155 if(*src == '=') {
156 x <<= 6;
157 src++;
158 if(++padc > padding)
159 /* this is a badly placed '=' symbol! */
160 goto bad;
161 }
162 else {
163 val = lookup[(unsigned char)*src++];
164 if(val == 0xff) /* bad symbol */
165 goto bad;
166 x = (x << 6) | val;
167 }
168 }
169 if(padding == 1)
170 pos[1] = (x >> 8) & 0xff;
171 pos[0] = (x >> 16) & 0xff;
172 pos += 3 - padding;
173 }
174
175 /* Zero terminate */
176 *pos = '\0';
177
178 /* Return the decoded data */
179 *outptr = newstr;
180 *outlen = rawlen;
181
182 return CURLE_OK;
183 bad:
184 free(newstr);
185 return CURLE_BAD_CONTENT_ENCODING;
186 }
187
base64_encode(const char * table64,const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)188 static CURLcode base64_encode(const char *table64,
189 const char *inputbuff, size_t insize,
190 char **outptr, size_t *outlen)
191 {
192 char *output;
193 char *base64data;
194 const unsigned char *in = (unsigned char *)inputbuff;
195 const char *padstr = &table64[64]; /* Point to padding string. */
196
197 *outptr = NULL;
198 *outlen = 0;
199
200 if(!insize)
201 insize = strlen(inputbuff);
202
203 #if SIZEOF_SIZE_T == 4
204 if(insize > UINT_MAX/4)
205 return CURLE_OUT_OF_MEMORY;
206 #endif
207
208 base64data = output = malloc((insize + 2) / 3 * 4 + 1);
209 if(!output)
210 return CURLE_OUT_OF_MEMORY;
211
212 while(insize >= 3) {
213 *output++ = table64[ in[0] >> 2 ];
214 *output++ = table64[ ((in[0] & 0x03) << 4) | (in[1] >> 4) ];
215 *output++ = table64[ ((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6) ];
216 *output++ = table64[ in[2] & 0x3F ];
217 insize -= 3;
218 in += 3;
219 }
220 if(insize) {
221 /* this is only one or two bytes now */
222 *output++ = table64[ in[0] >> 2 ];
223 if(insize == 1) {
224 *output++ = table64[ ((in[0] & 0x03) << 4) ];
225 if(*padstr) {
226 *output++ = *padstr;
227 *output++ = *padstr;
228 }
229 }
230 else {
231 /* insize == 2 */
232 *output++ = table64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4) ];
233 *output++ = table64[ ((in[1] & 0x0F) << 2) ];
234 if(*padstr)
235 *output++ = *padstr;
236 }
237 }
238
239 /* Zero terminate */
240 *output = '\0';
241
242 /* Return the pointer to the new data (allocated memory) */
243 *outptr = base64data;
244
245 /* Return the length of the new data */
246 *outlen = (size_t)(output - base64data);
247
248 return CURLE_OK;
249 }
250
251 /*
252 * Curl_base64_encode()
253 *
254 * Given a pointer to an input buffer and an input size, encode it and
255 * return a pointer in *outptr to a newly allocated memory area holding
256 * encoded data. Size of encoded data is returned in variable pointed by
257 * outlen.
258 *
259 * Input length of 0 indicates input buffer holds a NUL-terminated string.
260 *
261 * Returns CURLE_OK on success, otherwise specific error code. Function
262 * output shall not be considered valid unless CURLE_OK is returned.
263 *
264 * @unittest: 1302
265 */
Curl_base64_encode(const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)266 CURLcode Curl_base64_encode(const char *inputbuff, size_t insize,
267 char **outptr, size_t *outlen)
268 {
269 return base64_encode(base64encdec, inputbuff, insize, outptr, outlen);
270 }
271
272 /*
273 * Curl_base64url_encode()
274 *
275 * Given a pointer to an input buffer and an input size, encode it and
276 * return a pointer in *outptr to a newly allocated memory area holding
277 * encoded data. Size of encoded data is returned in variable pointed by
278 * outlen.
279 *
280 * Input length of 0 indicates input buffer holds a NUL-terminated string.
281 *
282 * Returns CURLE_OK on success, otherwise specific error code. Function
283 * output shall not be considered valid unless CURLE_OK is returned.
284 *
285 * @unittest: 1302
286 */
Curl_base64url_encode(const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)287 CURLcode Curl_base64url_encode(const char *inputbuff, size_t insize,
288 char **outptr, size_t *outlen)
289 {
290 return base64_encode(base64url, inputbuff, insize, outptr, outlen);
291 }
292
293 #endif /* no users so disabled */
294
