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- #include "base64.h"
- #include <string.h>
- #include <stdlib.h>
- #include <stdio.h>
- #include <assert.h>
- /* Encoding table as described in RFC1113. */
- const static uint8_t b64_encode_table[] =
- "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
- "abcdefghijklmnopqrstuvwxyz0123456789+/";
- /* Decoding table. */
- const static int8_t b64_decode_table[256] = {
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 00-0F */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 10-1F */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 20-2F */
- 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 30-3F */
- -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 40-4F */
- 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 50-5F */
- -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 60-6F */
- 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 70-7F */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 80-8F */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 90-9F */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* A0-AF */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* B0-BF */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* C0-CF */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* D0-DF */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* E0-EF */
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 /* F0-FF */
- };
- uint8_t *base64decode(const uint8_t *src, const size_t buflen, size_t *retlen)
- {
- int8_t digit, lastdigit;
- size_t i, j;
- uint8_t *decoded;
- const size_t maxlen = ((buflen + 3) / 4) * 3;
- /* Sanity check */
- assert(src != NULL);
- digit = lastdigit = j = 0;
- decoded = malloc(maxlen + 1);
- if (decoded == NULL) return NULL;
- for (i = 0; i < buflen; ++i) {
- if ((digit = b64_decode_table[src[i]]) != -1) {
- /* Decode block */
- switch (i % 4) {
- case 1:
- decoded[j++] = ((lastdigit << 2) | ((digit & 0x30) >> 4));
- break;
- case 2:
- decoded[j++] = (((lastdigit & 0xF) << 4) | ((digit & 0x3C) >> 2));
- break;
- case 3:
- decoded[j++] = (((lastdigit & 0x03) << 6) | digit);
- break;
- }
- lastdigit = digit;
- }
- }
- if (retlen != NULL) *retlen = j;
- decoded[j] = '\0';
- return decoded; /* Must be free()'d by caller */
- }
- uint8_t *base64encode(const uint8_t *src, const size_t buflen, size_t *retlen)
- {
- size_t i, j;
- const size_t maxlen = (((buflen + 3) & ~3)) * 4;
- uint8_t *encoded = malloc(maxlen + 1);
- if (encoded == NULL) return NULL;
- /* Sanity check */
- assert(src != NULL);
- assert(buflen > 0);
- j = 0;
- for (i = 0; i < buflen + 1; ++i) {
- /* Encode block */
- switch (i % 3) {
- case 0:
- encoded[j++] = b64_encode_table[src[i] >> 2];
- encoded[j++] = b64_encode_table[((src[i] & 0x03) << 4) |
- ((src[i + 1] & 0xF0) >> 4)];
- break;
- case 1:
- encoded[j++] = b64_encode_table[((src[i] & 0x0F) << 2) |
- ((src[i + 1] & 0xC0) >> 6)];
- break;
- case 2:
- encoded[j++] = b64_encode_table[(src[i] & 0x3F)];
- break;
- }
- }
- /* Add padding if necessary */
- if ((j % 4) != 0) {
- const size_t with_padding = ((j + 3) & ~3); /* Align to 4 bytes */
- do {
- encoded[j++] = '=';
- } while (j < with_padding);
- }
- assert(j <= maxlen);
- if (retlen != NULL) *retlen = j;
- encoded[j] = '\0';
- return encoded; /* Must be free()'d by caller */
- }
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