| 1 | #include <stdlib.h> |
| 2 | #include <string.h> |
| 3 | #include <ctype.h> |
| 4 | |
| 5 | #include "base64.h" |
| 6 | |
| 7 | #define DEFAULT_CHARLIST "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" |
| 8 | |
| 9 | #define BASE64_PADDING 0x40 |
| 10 | #define BASE64_INVALID 0x80 |
| 11 | |
| 12 | struct base64_s { |
| 13 | char charlist[65]; |
| 14 | char charmap[256]; |
| 15 | int charmap_inited; |
| 16 | |
| 17 | int use_padding; |
| 18 | int skip_spaces; |
| 19 | }; |
| 20 | |
| 21 | static base64_t default_base64 = |
| 22 | { .charlist = DEFAULT_CHARLIST, |
| 23 | .use_padding = 1 }; |
| 24 | |
| 25 | static void |
| 26 | initialize_charmap(base64_t *base64) |
| 27 | { |
| 28 | int i; |
| 29 | |
| 30 | memset(base64->charmap, BASE64_INVALID, sizeof(base64->charmap)); |
| 31 | for (i=0; i<64; i++) { |
| 32 | base64->charmap[(int)base64->charlist[i]] = i; |
| 33 | } |
| 34 | base64->charmap['='] = BASE64_PADDING; |
| 35 | base64->charmap_inited = 1; |
| 36 | } |
| 37 | |
| 38 | base64_t * |
| 39 | base64_init(const char *charlist, int use_padding, int skip_spaces) |
| 40 | { |
| 41 | base64_t *base64; |
| 42 | int i; |
| 43 | |
| 44 | if (!charlist) { |
| 45 | charlist = DEFAULT_CHARLIST; |
| 46 | } |
| 47 | if (strlen(charlist) != 64) { |
| 48 | return NULL; |
| 49 | } |
| 50 | for (i=0; i<64; i++) { |
| 51 | switch (charlist[i]) { |
| 52 | case '\r': |
| 53 | case '\n': |
| 54 | case '=': |
| 55 | return NULL; |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | base64 = calloc(1, sizeof(base64_t)); |
| 60 | if (!base64) { |
| 61 | return NULL; |
| 62 | } |
| 63 | strncpy(base64->charlist, charlist, sizeof(base64->charlist)-1); |
| 64 | base64->use_padding = use_padding; |
| 65 | base64->skip_spaces = skip_spaces; |
| 66 | |
| 67 | return base64; |
| 68 | } |
| 69 | |
| 70 | void |
| 71 | base64_destroy(base64_t *base64) |
| 72 | { |
| 73 | free(base64); |
| 74 | } |
| 75 | |
| 76 | int |
| 77 | base64_encoded_length(base64_t *base64, int srclen) |
| 78 | { |
| 79 | if (!base64) { |
| 80 | base64 = &default_base64; |
| 81 | } |
| 82 | |
| 83 | if (base64->use_padding) { |
| 84 | return ((srclen+2)/3*4)+1; |
| 85 | } else { |
| 86 | int strlen = 0; |
| 87 | switch (srclen % 3) { |
| 88 | case 2: |
| 89 | strlen += 1; |
| 90 | case 1: |
| 91 | strlen += 2; |
| 92 | default: |
| 93 | strlen += srclen/3*4; |
| 94 | break; |
| 95 | } |
| 96 | return strlen+1; |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | int |
| 101 | base64_encode(base64_t *base64, char *dst, const unsigned char *src, int srclen) |
| 102 | { |
| 103 | int src_idx, dst_idx; |
| 104 | int residue; |
| 105 | |
| 106 | if (!base64) { |
| 107 | base64 = &default_base64; |
| 108 | } |
| 109 | |
| 110 | residue = 0; |
| 111 | for (src_idx=dst_idx=0; src_idx<srclen; src_idx++) { |
| 112 | residue |= src[src_idx]; |
| 113 | |
| 114 | switch (src_idx%3) { |
| 115 | case 0: |
| 116 | dst[dst_idx++] = base64->charlist[(residue>>2)%64]; |
| 117 | residue &= 0x03; |
| 118 | break; |
| 119 | case 1: |
| 120 | dst[dst_idx++] = base64->charlist[residue>>4]; |
| 121 | residue &= 0x0f; |
| 122 | break; |
| 123 | case 2: |
| 124 | dst[dst_idx++] = base64->charlist[residue>>6]; |
| 125 | dst[dst_idx++] = base64->charlist[residue&0x3f]; |
| 126 | residue = 0; |
| 127 | break; |
| 128 | } |
| 129 | residue <<= 8; |
| 130 | } |
| 131 | |
| 132 | /* Add padding */ |
| 133 | if (src_idx%3 == 1) { |
| 134 | dst[dst_idx++] = base64->charlist[residue>>4]; |
| 135 | if (base64->use_padding) { |
| 136 | dst[dst_idx++] = '='; |
| 137 | dst[dst_idx++] = '='; |
| 138 | } |
| 139 | } else if (src_idx%3 == 2) { |
| 140 | dst[dst_idx++] = base64->charlist[residue>>6]; |
| 141 | if (base64->use_padding) { |
| 142 | dst[dst_idx++] = '='; |
| 143 | } |
| 144 | } |
| 145 | dst[dst_idx] = '\0'; |
| 146 | return dst_idx; |
| 147 | } |
| 148 | |
| 149 | int |
| 150 | base64_decode(base64_t *base64, unsigned char **dst, const char *src, int srclen) |
| 151 | { |
| 152 | char *inbuf; |
| 153 | int inbuflen; |
| 154 | unsigned char *outbuf; |
| 155 | int outbuflen; |
| 156 | char *srcptr; |
| 157 | int index; |
| 158 | |
| 159 | if (!base64) { |
| 160 | base64 = &default_base64; |
| 161 | } |
| 162 | if (!base64->charmap_inited) { |
| 163 | initialize_charmap(base64); |
| 164 | } |
| 165 | |
| 166 | inbuf = malloc(srclen+4); |
| 167 | if (!inbuf) { |
| 168 | return -1; |
| 169 | } |
| 170 | memcpy(inbuf, src, srclen); |
| 171 | inbuf[srclen] = '\0'; |
| 172 | |
| 173 | /* Remove all whitespaces from inbuf */ |
| 174 | if (base64->skip_spaces) { |
| 175 | int i, inbuflen = strlen(inbuf); |
| 176 | for (i=0; i<inbuflen; i++) { |
| 177 | if (inbuf[i] == '\0') { |
| 178 | break; |
| 179 | } else if (isspace(inbuf[i])) { |
| 180 | memmove(inbuf+i, inbuf+i+1, inbuflen-i); |
| 181 | inbuflen -= 1; |
| 182 | i -= 1; |
| 183 | } |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | /* Add padding to inbuf if required */ |
| 188 | inbuflen = strlen(inbuf); |
| 189 | if (!base64->use_padding) { |
| 190 | if (inbuflen%4 == 1) { |
| 191 | free(inbuf); |
| 192 | return -2; |
| 193 | } |
| 194 | if (inbuflen%4 == 2) { |
| 195 | inbuf[inbuflen] = '='; |
| 196 | inbuf[inbuflen+1] = '='; |
| 197 | inbuf[inbuflen+2] = '\0'; |
| 198 | inbuflen += 2; |
| 199 | } else if (inbuflen%4 == 3) { |
| 200 | inbuf[inbuflen] = '='; |
| 201 | inbuf[inbuflen+1] = '\0'; |
| 202 | inbuflen += 1; |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | /* Make sure data is divisible by 4 */ |
| 207 | if (inbuflen%4 != 0) { |
| 208 | free(inbuf); |
| 209 | return -3; |
| 210 | } |
| 211 | |
| 212 | /* Calculate the output length without padding */ |
| 213 | outbuflen = inbuflen/4*3; |
| 214 | if (inbuflen >= 4 && inbuf[inbuflen-1] == '=') { |
| 215 | outbuflen -= 1; |
| 216 | if (inbuf[inbuflen-2] == '=') { |
| 217 | outbuflen -= 1; |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | /* Allocate buffer for outputting data */ |
| 222 | outbuf = malloc(outbuflen); |
| 223 | if (!outbuf) { |
| 224 | free(inbuf); |
| 225 | return -4; |
| 226 | } |
| 227 | |
| 228 | index = 0; |
| 229 | srcptr = inbuf; |
| 230 | while (*srcptr) { |
| 231 | unsigned char a = base64->charmap[(unsigned char)*(srcptr++)]; |
| 232 | unsigned char b = base64->charmap[(unsigned char)*(srcptr++)]; |
| 233 | unsigned char c = base64->charmap[(unsigned char)*(srcptr++)]; |
| 234 | unsigned char d = base64->charmap[(unsigned char)*(srcptr++)]; |
| 235 | |
| 236 | if (a == BASE64_INVALID || b == BASE64_INVALID || |
| 237 | c == BASE64_INVALID || d == BASE64_INVALID) { |
| 238 | return -5; |
| 239 | } |
| 240 | if (a == BASE64_PADDING || b == BASE64_PADDING) { |
| 241 | return -6; |
| 242 | } |
| 243 | |
| 244 | /* Update the first byte */ |
| 245 | outbuf[index++] = (a << 2) | ((b & 0x30) >> 4); |
| 246 | |
| 247 | /* Update the second byte */ |
| 248 | if (c == BASE64_PADDING) { |
| 249 | break; |
| 250 | } |
| 251 | outbuf[index++] = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2); |
| 252 | |
| 253 | /* Update the third byte */ |
| 254 | if (d == BASE64_PADDING) { |
| 255 | break; |
| 256 | } |
| 257 | outbuf[index++] = ((c & 0x03) << 6) | d; |
| 258 | } |
| 259 | if (index != outbuflen) { |
| 260 | free(inbuf); |
| 261 | free(outbuf); |
| 262 | return -7; |
| 263 | } |
| 264 | |
| 265 | free(inbuf); |
| 266 | *dst = outbuf; |
| 267 | return outbuflen; |
| 268 | } |