lib/base64.c

   1
   2 #include "config.h"
   3
   4 #if HAVE_STDIO_H
   5 #include <stdio.h>
   6 #endif
   7 #if HAVE_STDLIB_H
   8 #include <stdlib.h>
   9 #endif
  10
  11 static void base64_init(void);
  12
  13 static int base64_initialized = 0;
  14 int base64_value[256];
  15 const char base64_code[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  16
  17
  18 static void
  19 base64_init(void)
  20 {
  21     int i;
  22
  23     for (i = 0; i < 256; i++)
  24         base64_value[i] = -1;
  25
  26     for (i = 0; i < 64; i++)
  27         base64_value[(int) base64_code[i]] = i;
  28     base64_value['='] = 0;
  29
  30     base64_initialized = 1;
  31 }
  32
  33 char *
  34 base64_decode(const char *p)
  35 {
  36     static char result[8192];
  37     int c;
  38     long val;
  39     int i;
  40     char *d;
  41
  42     if (!p)
  43         return NULL;
  44
  45     if (!base64_initialized)
  46         base64_init();
  47
  48     val = c = 0;
  49     d = result;
  50     while (*p) {
  51         i = base64_value[(int) *p++];
  52         if (i >= 0) {
  53             val = val * 64 + i;
  54             c++;
  55         }
  56         if (c == 4) {           /* One quantum of four encoding characters/24 bit */
  57             *d++ = val >> 16;   /* High 8 bits */
  58             *d++ = (val >> 8) & 0xff;   /* Mid 8 bits */
  59             *d++ = val & 0xff;  /* Low 8 bits */
  60             val = c = 0;
  61         }
  62     }
  63     *d = 0;
  64     return *result ? result : NULL;
  65 }
  66
  67 /* adopted from http://ftp.sunet.se/pub2/gnu/vm/base64-encode.c with adjustments */
  68 const char *
  69 base64_encode(const char *decoded_str)
  70 {
  71     static char result[8192];
  72     int bits = 0;
  73     int char_count = 0;
  74     int out_cnt = 0;
  75     int c;
  76
  77     if (!decoded_str)
  78         return decoded_str;
  79
  80     if (!base64_initialized)
  81         base64_init();
  82
  83     while ((c = *decoded_str++) && out_cnt < sizeof(result) - 1) {
  84         bits += c;
  85         char_count++;
  86         if (char_count == 3) {
  87             result[out_cnt++] = base64_code[bits >> 18];
  88             result[out_cnt++] = base64_code[(bits >> 12) & 0x3f];
  89             result[out_cnt++] = base64_code[(bits >> 6) & 0x3f];
  90             result[out_cnt++] = base64_code[bits & 0x3f];
  91             bits = 0;
  92             char_count = 0;
  93         } else {
  94             bits <<= 8;
  95         }
  96     }
  97     if (char_count != 0) {
  98         bits <<= 16 - (8 * char_count);
  99         result[out_cnt++] = base64_code[bits >> 18];
 100         result[out_cnt++] = base64_code[(bits >> 12) & 0x3f];
 101         if (char_count == 1) {
 102             result[out_cnt++] = '=';
 103             result[out_cnt++] = '=';
 104         } else {
 105             result[out_cnt++] = base64_code[(bits >> 6) & 0x3f];
 106             result[out_cnt++] = '=';
 107         }
 108     }
 109     result[out_cnt] = '\0';     /* terminate */
 110     return result;
 111 }