+ /* Pad the result if necessary... */
+ if (i == length + 1)
+ *(p - 1) = '=';
+ else if (i == length + 2)
+ *(p - 1) = *(p - 2) = '=';
+ /* ...and zero-terminate it. */
+ *p = '\0';
+}
+
+#define IS_ASCII(c) (((c) & 0x80) == 0)
+#define IS_BASE64(c) ((IS_ASCII (c) && base64_char_to_value[c] >= 0) || c == '=')
+
+/* Get next character from the string, except that non-base64
+ characters are ignored, as mandated by rfc2045. */
+#define NEXT_BASE64_CHAR(c, p) do { \
+ c = *p++; \
+} while (c != '\0' && !IS_BASE64 (c))
+
+/* Decode data from BASE64 (assumed to be encoded as base64) into
+ memory pointed to by TO. TO should be large enough to accomodate
+ the decoded data, which is guaranteed to be less than
+ strlen(base64).
+
+ Since TO is assumed to contain binary data, it is not
+ NUL-terminated. The function returns the length of the data
+ written to TO. -1 is returned in case of error caused by malformed
+ base64 input. */
+
+int
+base64_decode (const char *base64, char *to)
+{
+ /* Table of base64 values for first 128 characters. */
+ static short base64_char_to_value[128] =
+ {
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0- 9 */
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 10- 19 */
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 20- 29 */
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 30- 39 */
+ -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, /* 40- 49 */
+ 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, /* 50- 59 */
+ -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, /* 60- 69 */
+ 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 70- 79 */
+ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, /* 80- 89 */
+ 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, /* 90- 99 */
+ 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, /* 100-109 */
+ 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, /* 110-119 */
+ 49, 50, 51, -1, -1, -1, -1, -1 /* 120-127 */
+ };
+
+ const char *p = base64;
+ char *q = to;
+
+ while (1)