Function base64decode

ut.c:458–513

function that decodes from base64 * output buffer is assumed to have the right length */

/* function that decodes from base64
 * output buffer is assumed to have the right length */
int base64decode(unsigned char *out, unsigned char *in, int len)
{
	int i=0;
	unsigned char c1,c2,c3,c4;
	int out_len=0;

	while (len > i)
	{
		do
		{
			c1 = base64val[in[i++]];
		} while (i<len && c1 == BAD);

		if (c1 == BAD)
			break;

		do
		{
			c2 = base64val[in[i++]];
		} while (i<len && c2 == BAD);

		if (c2 == BAD)
			break;

		out[out_len++] = (c1 << 2) | ((c2 & 0x30) >> 4);

		do
		{
			c3 = in[i++];
			if (c3 == 61)
				return out_len;

			c3 = base64val[c3];
		} while (i<len && c3 == BAD);

		if (c3 == BAD)
			break;

		out[out_len++] = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);

		do
		{
			c4 = in[i++];
			if (c4 == 61)
				return out_len;
			c4 = base64val[c4];
		} while (i<len && c4 == BAD);

		if (c4 == BAD)
			break;

		out[out_len++] = ((c3 & 0x03) << 6) | c4;
	}

	return out_len;
}

/* function that decodes from base64URL