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_DOH) || defined(USE_SSL)
35
36 #include "urldata.h" /* for the Curl_easy definition */
37 #include "warnless.h"
38 #include "curl_base64.h"
39
40 /* The last 2 #include files should be in this order */
41 #include "curl_memory.h"
42 #include "memdebug.h"
43
44 /* ---- Base64 Encoding/Decoding Table --- */
45 /* Padding character string starts at offset 64. */
46 static const char base64[]=
47 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
48
49 /* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648
50 section 5 */
51 static const char base64url[]=
52 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
53
54 static const unsigned char decodetable[] =
55 { 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255,
56 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
57 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28,
58 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
59 48, 49, 50, 51 };
60 /*
61 * Curl_base64_decode()
62 *
63 * Given a base64 NUL-terminated string at src, decode it and return a
64 * pointer in *outptr to a newly allocated memory area holding decoded
65 * data. Size of decoded data is returned in variable pointed by outlen.
66 *
67 * Returns CURLE_OK on success, otherwise specific error code. Function
68 * output shall not be considered valid unless CURLE_OK is returned.
69 *
70 * When decoded data length is 0, returns NULL in *outptr.
71 *
72 * @unittest: 1302
73 */
Curl_base64_decode(const char * src,unsigned char ** outptr,size_t * outlen)74 CURLcode Curl_base64_decode(const char *src,
75 unsigned char **outptr, size_t *outlen)
76 {
77 size_t srclen = 0;
78 size_t padding = 0;
79 size_t i;
80 size_t numQuantums;
81 size_t fullQuantums;
82 size_t rawlen = 0;
83 unsigned char *pos;
84 unsigned char *newstr;
85 unsigned char lookup[256];
86
87 *outptr = NULL;
88 *outlen = 0;
89 srclen = strlen(src);
90
91 /* Check the length of the input string is valid */
92 if(!srclen || srclen % 4)
93 return CURLE_BAD_CONTENT_ENCODING;
94
95 /* srclen is at least 4 here */
96 while(src[srclen - 1 - padding] == '=') {
97 /* count padding characters */
98 padding++;
99 /* A maximum of two = padding characters is allowed */
100 if(padding > 2)
101 return CURLE_BAD_CONTENT_ENCODING;
102 }
103
104 /* Calculate the number of quantums */
105 numQuantums = srclen / 4;
106 fullQuantums = numQuantums - (padding ? 1 : 0);
107
108 /* Calculate the size of the decoded string */
109 rawlen = (numQuantums * 3) - padding;
110
111 /* Allocate our buffer including room for a null-terminator */
112 newstr = malloc(rawlen + 1);
113 if(!newstr)
114 return CURLE_OUT_OF_MEMORY;
115
116 pos = newstr;
117
118 memset(lookup, 0xff, sizeof(lookup));
119 memcpy(&lookup['+'], decodetable, sizeof(decodetable));
120 /* replaces
121 {
122 unsigned char c;
123 const unsigned char *p = (const unsigned char *)base64;
124 for(c = 0; *p; c++, p++)
125 lookup[*p] = c;
126 }
127 */
128
129 /* Decode the complete quantums first */
130 for(i = 0; i < fullQuantums; i++) {
131 unsigned char val;
132 unsigned int x = 0;
133 int j;
134
135 for(j = 0; j < 4; j++) {
136 val = lookup[(unsigned char)*src++];
137 if(val == 0xff) /* bad symbol */
138 goto bad;
139 x = (x << 6) | val;
140 }
141 pos[2] = x & 0xff;
142 pos[1] = (x >> 8) & 0xff;
143 pos[0] = (x >> 16) & 0xff;
144 pos += 3;
145 }
146 if(padding) {
147 /* this means either 8 or 16 bits output */
148 unsigned char val;
149 unsigned int x = 0;
150 int j;
151 size_t padc = 0;
152 for(j = 0; j < 4; j++) {
153 if(*src == '=') {
154 x <<= 6;
155 src++;
156 if(++padc > padding)
157 /* this is a badly placed '=' symbol! */
158 goto bad;
159 }
160 else {
161 val = lookup[(unsigned char)*src++];
162 if(val == 0xff) /* bad symbol */
163 goto bad;
164 x = (x << 6) | val;
165 }
166 }
167 if(padding == 1)
168 pos[1] = (x >> 8) & 0xff;
169 pos[0] = (x >> 16) & 0xff;
170 pos += 3 - padding;
171 }
172
173 /* Zero terminate */
174 *pos = '\0';
175
176 /* Return the decoded data */
177 *outptr = newstr;
178 *outlen = rawlen;
179
180 return CURLE_OK;
181 bad:
182 free(newstr);
183 return CURLE_BAD_CONTENT_ENCODING;
184 }
185
base64_encode(const char * table64,const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)186 static CURLcode base64_encode(const char *table64,
187 const char *inputbuff, size_t insize,
188 char **outptr, size_t *outlen)
189 {
190 char *output;
191 char *base64data;
192 const unsigned char *in = (unsigned char *)inputbuff;
193 const char *padstr = &table64[64]; /* Point to padding string. */
194
195 *outptr = NULL;
196 *outlen = 0;
197
198 if(!insize)
199 insize = strlen(inputbuff);
200
201 #if SIZEOF_SIZE_T == 4
202 if(insize > UINT_MAX/4)
203 return CURLE_OUT_OF_MEMORY;
204 #endif
205
206 base64data = output = malloc((insize + 2) / 3 * 4 + 1);
207 if(!output)
208 return CURLE_OUT_OF_MEMORY;
209
210 while(insize >= 3) {
211 *output++ = table64[ in[0] >> 2 ];
212 *output++ = table64[ ((in[0] & 0x03) << 4) | (in[1] >> 4) ];
213 *output++ = table64[ ((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6) ];
214 *output++ = table64[ in[2] & 0x3F ];
215 insize -= 3;
216 in += 3;
217 }
218 if(insize) {
219 /* this is only one or two bytes now */
220 *output++ = table64[ in[0] >> 2 ];
221 if(insize == 1) {
222 *output++ = table64[ ((in[0] & 0x03) << 4) ];
223 if(*padstr) {
224 *output++ = *padstr;
225 *output++ = *padstr;
226 }
227 }
228 else {
229 /* insize == 2 */
230 *output++ = table64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4) ];
231 *output++ = table64[ ((in[1] & 0x0F) << 2) ];
232 if(*padstr)
233 *output++ = *padstr;
234 }
235 }
236
237 /* Zero terminate */
238 *output = '\0';
239
240 /* Return the pointer to the new data (allocated memory) */
241 *outptr = base64data;
242
243 /* Return the length of the new data */
244 *outlen = output - base64data;
245
246 return CURLE_OK;
247 }
248
249 /*
250 * Curl_base64_encode()
251 *
252 * Given a pointer to an input buffer and an input size, encode it and
253 * return a pointer in *outptr to a newly allocated memory area holding
254 * encoded data. Size of encoded data is returned in variable pointed by
255 * outlen.
256 *
257 * Input length of 0 indicates input buffer holds a NUL-terminated string.
258 *
259 * Returns CURLE_OK on success, otherwise specific error code. Function
260 * output shall not be considered valid unless CURLE_OK is returned.
261 *
262 * @unittest: 1302
263 */
Curl_base64_encode(const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)264 CURLcode Curl_base64_encode(const char *inputbuff, size_t insize,
265 char **outptr, size_t *outlen)
266 {
267 return base64_encode(base64, inputbuff, insize, outptr, outlen);
268 }
269
270 /*
271 * Curl_base64url_encode()
272 *
273 * Given a pointer to an input buffer and an input size, encode it and
274 * return a pointer in *outptr to a newly allocated memory area holding
275 * encoded data. Size of encoded data is returned in variable pointed by
276 * outlen.
277 *
278 * Input length of 0 indicates input buffer holds a NUL-terminated string.
279 *
280 * Returns CURLE_OK on success, otherwise specific error code. Function
281 * output shall not be considered valid unless CURLE_OK is returned.
282 *
283 * @unittest: 1302
284 */
Curl_base64url_encode(const char * inputbuff,size_t insize,char ** outptr,size_t * outlen)285 CURLcode Curl_base64url_encode(const char *inputbuff, size_t insize,
286 char **outptr, size_t *outlen)
287 {
288 return base64_encode(base64url, inputbuff, insize, outptr, outlen);
289 }
290
291 #endif /* no users so disabled */
292