/*
 * Base64 encoding/decoding (RFC1341)
 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
 * Copyright (c) 2022 Loïc Gomez
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "base64.h"

static const unsigned char base64_table[65] =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**
 * base64_encode - Base64 encode
 * @src: Data to be encoded
 * @len: Length of the data to be encoded
 * @out_len: Pointer to output length variable, or %NULL if not used
 * Returns: Allocated buffer of out_len bytes of encoded data,
 * or %NULL on failure
 *
 * Caller is responsible for freeing the returned buffer. Returned buffer is
 * nul terminated to make it easier to use as a C string. The nul terminator is
 * not included in out_len.
 *
 * BIP change: remove line returns.
 */
unsigned char *base64_encode(const unsigned char *src, size_t len,
			     size_t *out_len)
{
	unsigned char *out, *pos;
	const unsigned char *end, *in;
	size_t olen;
	int line_len;

	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
	olen += olen / 72;	/* line feeds */
	olen++;			/* nul termination */
	if (olen < len)
		return NULL; /* integer overflow */
	out = malloc(olen);
	if (out == NULL)
		return NULL;

	end = src + len;
	in = src;
	pos = out;
	line_len = 0;
	while (end - in >= 3) {
		*pos++ = base64_table[in[0] >> 2];
		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
		*pos++ = base64_table[in[2] & 0x3f];
		in += 3;
		line_len += 4;
		/*
		 *  BIP change: remove line returns.
		if (line_len >= 72) {
			*pos++ = '\n';
			line_len = 0;
		}
		*/
	}

	if (end - in) {
		*pos++ = base64_table[in[0] >> 2];
		if (end - in == 1) {
			*pos++ = base64_table[(in[0] & 0x03) << 4];
			*pos++ = '=';
		} else {
			*pos++ = base64_table[((in[0] & 0x03) << 4)
					      | (in[1] >> 4)];
			*pos++ = base64_table[(in[1] & 0x0f) << 2];
		}
		*pos++ = '=';
		line_len += 4;
	}

	/*
	 *  BIP change: remove line returns.
	if (line_len)
		*pos++ = '\n';
	*/

	*pos = '\0';
	if (out_len)
		*out_len = (size_t)(pos - out);
	return out;
}