base64.c (8363B)
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_LIBCURL) 36 #include <curl/curl.h> 37 #include "warnless.h" 38 #include "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 const char Curl_base64encdec[]= 48 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 49 50 /* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648 51 section 5 */ 52 static const char base64url[]= 53 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; 54 55 static const unsigned char decodetable[] = 56 { 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 57 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 58 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28, 59 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 60 48, 49, 50, 51 }; 61 /* 62 * curlx_base64_decode() 63 * 64 * Given a base64 null-terminated string at src, decode it and return a 65 * pointer in *outptr to a newly allocated memory area holding decoded data. 66 * Size of decoded data is returned in variable pointed by outlen. 67 * 68 * Returns CURLE_OK on success, otherwise specific error code. Function 69 * output shall not be considered valid unless CURLE_OK is returned. 70 * 71 * When decoded data length is 0, returns NULL in *outptr. 72 * 73 * @unittest: 1302 74 */ 75 CURLcode curlx_base64_decode(const char *src, 76 unsigned char **outptr, size_t *outlen) 77 { 78 size_t srclen = 0; 79 size_t padding = 0; 80 size_t i; 81 size_t numQuantums; 82 size_t fullQuantums; 83 size_t rawlen = 0; 84 unsigned char *pos; 85 unsigned char *newstr; 86 unsigned char lookup[256]; 87 88 *outptr = NULL; 89 *outlen = 0; 90 srclen = strlen(src); 91 92 /* Check the length of the input string is valid */ 93 if(!srclen || srclen % 4) 94 return CURLE_BAD_CONTENT_ENCODING; 95 96 /* srclen is at least 4 here */ 97 while(src[srclen - 1 - padding] == '=') { 98 /* count padding characters */ 99 padding++; 100 /* A maximum of two = padding characters is allowed */ 101 if(padding > 2) 102 return CURLE_BAD_CONTENT_ENCODING; 103 } 104 105 /* Calculate the number of quantums */ 106 numQuantums = srclen / 4; 107 fullQuantums = numQuantums - (padding ? 1 : 0); 108 109 /* Calculate the size of the decoded string */ 110 rawlen = (numQuantums * 3) - padding; 111 112 /* Allocate our buffer including room for a null-terminator */ 113 newstr = malloc(rawlen + 1); 114 if(!newstr) 115 return CURLE_OUT_OF_MEMORY; 116 117 pos = newstr; 118 119 memset(lookup, 0xff, sizeof(lookup)); 120 memcpy(&lookup['+'], decodetable, sizeof(decodetable)); 121 122 /* Decode the complete quantums first */ 123 for(i = 0; i < fullQuantums; i++) { 124 unsigned char val; 125 unsigned int x = 0; 126 int j; 127 128 for(j = 0; j < 4; j++) { 129 val = lookup[(unsigned char)*src++]; 130 if(val == 0xff) /* bad symbol */ 131 goto bad; 132 x = (x << 6) | val; 133 } 134 pos[2] = x & 0xff; 135 pos[1] = (x >> 8) & 0xff; 136 pos[0] = (x >> 16) & 0xff; 137 pos += 3; 138 } 139 if(padding) { 140 /* this means either 8 or 16 bits output */ 141 unsigned char val; 142 unsigned int x = 0; 143 int j; 144 size_t padc = 0; 145 for(j = 0; j < 4; j++) { 146 if(*src == '=') { 147 x <<= 6; 148 src++; 149 if(++padc > padding) 150 /* this is a badly placed '=' symbol! */ 151 goto bad; 152 } 153 else { 154 val = lookup[(unsigned char)*src++]; 155 if(val == 0xff) /* bad symbol */ 156 goto bad; 157 x = (x << 6) | val; 158 } 159 } 160 if(padding == 1) 161 pos[1] = (x >> 8) & 0xff; 162 pos[0] = (x >> 16) & 0xff; 163 pos += 3 - padding; 164 } 165 166 /* Zero terminate */ 167 *pos = '\0'; 168 169 /* Return the decoded data */ 170 *outptr = newstr; 171 *outlen = rawlen; 172 173 return CURLE_OK; 174 bad: 175 free(newstr); 176 return CURLE_BAD_CONTENT_ENCODING; 177 } 178 179 static CURLcode base64_encode(const char *table64, 180 unsigned char padbyte, 181 const char *inputbuff, size_t insize, 182 char **outptr, size_t *outlen) 183 { 184 char *output; 185 char *base64data; 186 const unsigned char *in = (const unsigned char *)inputbuff; 187 188 *outptr = NULL; 189 *outlen = 0; 190 191 if(!insize) 192 insize = strlen(inputbuff); 193 194 #if SIZEOF_SIZE_T == 4 195 if(insize > UINT_MAX/4) 196 return CURLE_OUT_OF_MEMORY; 197 #endif 198 199 base64data = output = malloc((insize + 2) / 3 * 4 + 1); 200 if(!output) 201 return CURLE_OUT_OF_MEMORY; 202 203 while(insize >= 3) { 204 *output++ = table64[ in[0] >> 2 ]; 205 *output++ = table64[ ((in[0] & 0x03) << 4) | (in[1] >> 4) ]; 206 *output++ = table64[ ((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6) ]; 207 *output++ = table64[ in[2] & 0x3F ]; 208 insize -= 3; 209 in += 3; 210 } 211 if(insize) { 212 /* this is only one or two bytes now */ 213 *output++ = table64[ in[0] >> 2 ]; 214 if(insize == 1) { 215 *output++ = table64[ ((in[0] & 0x03) << 4) ]; 216 if(padbyte) { 217 *output++ = padbyte; 218 *output++ = padbyte; 219 } 220 } 221 else { 222 /* insize == 2 */ 223 *output++ = table64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4) ]; 224 *output++ = table64[ ((in[1] & 0x0F) << 2) ]; 225 if(padbyte) 226 *output++ = padbyte; 227 } 228 } 229 230 /* Zero terminate */ 231 *output = '\0'; 232 233 /* Return the pointer to the new data (allocated memory) */ 234 *outptr = base64data; 235 236 /* Return the length of the new data */ 237 *outlen = (size_t)(output - base64data); 238 239 return CURLE_OK; 240 } 241 242 /* 243 * curlx_base64_encode() 244 * 245 * Given a pointer to an input buffer and an input size, encode it and 246 * return a pointer in *outptr to a newly allocated memory area holding 247 * encoded data. Size of encoded data is returned in variable pointed by 248 * outlen. 249 * 250 * Input length of 0 indicates input buffer holds a null-terminated string. 251 * 252 * Returns CURLE_OK on success, otherwise specific error code. Function 253 * output shall not be considered valid unless CURLE_OK is returned. 254 * 255 * @unittest: 1302 256 */ 257 CURLcode curlx_base64_encode(const char *inputbuff, size_t insize, 258 char **outptr, size_t *outlen) 259 { 260 return base64_encode(Curl_base64encdec, '=', 261 inputbuff, insize, outptr, outlen); 262 } 263 264 /* 265 * curlx_base64url_encode() 266 * 267 * Given a pointer to an input buffer and an input size, encode it and 268 * return a pointer in *outptr to a newly allocated memory area holding 269 * encoded data. Size of encoded data is returned in variable pointed by 270 * outlen. 271 * 272 * Input length of 0 indicates input buffer holds a null-terminated string. 273 * 274 * Returns CURLE_OK on success, otherwise specific error code. Function 275 * output shall not be considered valid unless CURLE_OK is returned. 276 * 277 * @unittest: 1302 278 */ 279 CURLcode curlx_base64url_encode(const char *inputbuff, size_t insize, 280 char **outptr, size_t *outlen) 281 { 282 return base64_encode(base64url, 0, inputbuff, insize, outptr, outlen); 283 } 284 285 #endif /* no users so disabled */