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added simple base64 library

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1 parent 54dc633 commit 53da105d4745e2332c3b47283bf87f6cf9062144 Atbrox committed Jul 29, 2012
Showing with 101 additions and 0 deletions.
  1. +101 −0 atbrtst/client/base64.h
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+#ifndef _BASE64
+#define _BASE64
+
+// Example taken from: http://stackoverflow.com/questions/342409/how-do-i-base64-encode-decode-in-c
+
+#include <math.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+static char encoding_table[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+ 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
+ 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+ 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
+ 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
+ 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
+ 'w', 'x', 'y', 'z', '0', '1', '2', '3',
+ '4', '5', '6', '7', '8', '9', '+', '/'};
+static char *decoding_table = NULL;
+static int mod_table[] = {0, 2, 1};
+
+
+char *base64_encode(const char *data,
+ size_t input_length,
+ size_t *output_length) {
+
+ *output_length = (size_t) (4.0 * ceil((double) input_length / 3.0));
+
+ char *encoded_data = malloc(*output_length);
+ if (encoded_data == NULL) return NULL;
+
+ for (int i = 0, j = 0; i < input_length;) {
+
+ uint32_t octet_a = i < input_length ? data[i++] : 0;
+ uint32_t octet_b = i < input_length ? data[i++] : 0;
+ uint32_t octet_c = i < input_length ? data[i++] : 0;
+
+ uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;
+
+ encoded_data[j++] = encoding_table[(triple >> 3 * 6) & 0x3F];
+ encoded_data[j++] = encoding_table[(triple >> 2 * 6) & 0x3F];
+ encoded_data[j++] = encoding_table[(triple >> 1 * 6) & 0x3F];
+ encoded_data[j++] = encoding_table[(triple >> 0 * 6) & 0x3F];
+ }
+
+ for (int i = 0; i < mod_table[input_length % 3]; i++)
+ encoded_data[*output_length - 1 - i] = '=';
+
+ return encoded_data;
+}
+
+
+char *base64_decode(const char *data,
+ size_t input_length,
+ size_t *output_length) {
+
+ if (decoding_table == NULL) build_decoding_table();
+
+ if (input_length % 4 != 0) return NULL;
+
+ *output_length = input_length / 4 * 3;
+ if (data[input_length - 1] == '=') (*output_length)--;
+ if (data[input_length - 2] == '=') (*output_length)--;
+
+ char *decoded_data = malloc(*output_length);
+ if (decoded_data == NULL) return NULL;
+
+ for (int i = 0, j = 0; i < input_length;) {
+
+ uint32_t sextet_a = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
+ uint32_t sextet_b = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
+ uint32_t sextet_c = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
+ uint32_t sextet_d = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
+
+ uint32_t triple = (sextet_a << 3 * 6)
+ + (sextet_b << 2 * 6)
+ + (sextet_c << 1 * 6)
+ + (sextet_d << 0 * 6);
+
+ if (j < *output_length) decoded_data[j++] = (triple >> 2 * 8) & 0xFF;
+ if (j < *output_length) decoded_data[j++] = (triple >> 1 * 8) & 0xFF;
+ if (j < *output_length) decoded_data[j++] = (triple >> 0 * 8) & 0xFF;
+ }
+
+ return decoded_data;
+}
+
+
+void build_decoding_table() {
+
+ decoding_table = malloc(256);
+
+ for (int i = 0; i < 0x40; i++)
+ decoding_table[encoding_table[i]] = i;
+}
+
+
+void base64_cleanup() {
+ free(decoding_table);
+}
+
+#endif // _BASE64

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