diff options
Diffstat (limited to 'base64.c')
| -rw-r--r-- | base64.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/base64.c b/base64.c new file mode 100644 index 0000000..b5fecff --- /dev/null +++ b/base64.c @@ -0,0 +1,153 @@ +/* + This file is part of msr. + + msr is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + msr is distributed in the hope that it will be useful, but WITHOUT + ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public + License for more details. + + You should have received a copy of the GNU General Public License + along with Foobar. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include "base64.h" + +static const char b64padchar = (uint8_t)'='; +static const char b64chars[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/* +;; Precompute inverse lookup with skippable stuff and padding +(insert + (apply #'concat + (let ((str "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") + (skip " \t\n\r") (skipnum 65) + (pad ?=) (padnum 64) (invalidnum 66)) + (cl-loop for k from 0 to 255 + for j = (let* ((s (char-to-string k)) + (v (s-index-of s str)) + (w (s-index-of s skip)) + (x (char-equal k pad))) + (if v (format "%2dU " v) + (if w "SKIP" + (if x "PADD" "INVD")))) + collect (concat ", " j))))) +*/ +#define INVD (uint8_t)66 +#define SKIP (uint8_t)65 +#define PADD (uint8_t)64 +static const uint8_t b64inverse[256] = { + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, SKIP, SKIP, INVD, INVD, SKIP, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + SKIP, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, 62 , INVD, INVD, INVD, 63 , + 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , INVD, INVD, INVD, PADD, INVD, INVD, + INVD, 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , + 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , INVD, INVD, INVD, INVD, INVD, + INVD, 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , + 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, + INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD +}; + +Error bin_to_base64(uint8_t const * const bin, size_t binlen, + uint8_t *out, size_t maxoutsize, size_t *outlen) { + if ((*outlen = 4*(binlen/3)+4) > maxoutsize) return E_SMALL_BUFF; + size_t k, l; + uint32_t n = 0; + // Look at floor(binlen/3) groups of three bytes + for (k=0, l=0; k<binlen/3; k++) { + n = ((uint32_t)bin[3*k])<<16; + n |= ((uint32_t)bin[3*k+1])<<8; + n |= ((uint32_t)bin[3*k+2]); + + out[l++] = b64chars[(n>>18)&63]; + out[l++] = b64chars[(n>>12)&63]; + out[l++] = b64chars[(n>>6)&63]; + out[l++] = b64chars[n&63]; + } + // What is the actual index in bin? + k *= 3; + // Now deal with remainders + if (k<binlen) { + n = ((uint32_t)bin[k])<<16; + out[l+3] = b64padchar; + if (k+1<binlen) { + n |= ((uint32_t)bin[k+1])<<8; + out[l+2] = b64chars[(n>>6)&63]; + } else out[l+2] = b64padchar; + out[l] = b64chars[(n>>18)&63]; + out[l+1] = b64chars[(n>>12)&63]; + l+=4; + }; + out[l]=0; + return SUCCESS; +} + +// Note: will read first valid b64 encoded string and stop caring +Error base64_to_bin(uint8_t const * const str, size_t strlen, + uint8_t *buf, size_t bufmaxsize, size_t *buflen) { + if (str == NULL) return E_NULL; + *buflen = 0; + size_t k = 0; + uint8_t c = 0; + uint32_t t = 0; + while(k<strlen) { + uint8_t l = b64inverse[str[k++]]; + switch (l) { + // Skip = Skip, a universal truth + case SKIP: break; + // We don't take these transgressions lightly + case INVD: return E_B64_BAD_STR; + // Annoying validity checks here + case PADD: { + if (c<2) return E_B64_BAD_STR; + // If we have only consumed 2/4 chars, then there must be 2 x pad || .* || eof + if (c==2 && ( str[k]!=b64padchar)) + return E_B64_BAD_STR; + k = strlen; + // If we have 3/4 chars, pad || .* || eof + break; + } + // A valid b64 char (not incl. padding) + default: { + // Store these six bits + t = (t<<6) | l; + // If we've done this four times, then output three bytes + if (++c > 3) { + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)((t>>16)&255); + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)((t>>8)&255); + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)(t&255); + c = t = 0; + } + } + } + } + // This should not happen + if (c==1) return E_B64_BAD_STR; + // Finish up, c=2 => 1 byte, c=3 => 2 bytes + else if (c==2) { + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)((t>>4)&255); + } + else if (c==3) { + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)((t>>10)&255); + if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF; + buf[(*buflen)++] = (uint8_t)((t>>2)&255); + } + // done + return SUCCESS; +} |