/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "buffer.h"
#include "hex-binary.h"
#include "quoted-printable.h"

int quoted_printable_q_decode(const unsigned char *src, size_t src_size,
			      buffer_t *dest)
{
	char hexbuf[3];
	size_t src_pos, next;
	bool errors = FALSE;

	hexbuf[2] = '\0';

	next = 0;
	for (src_pos = 0; src_pos < src_size; src_pos++) {
		if (src[src_pos] != '_' && src[src_pos] != '=')
			continue;

		buffer_append(dest, src + next, src_pos - next);
		next = src_pos;

		if (src[src_pos] == '_') {
			buffer_append_c(dest, ' ');
			next++;
			continue;
		}

		if (src_pos+2 >= src_size)
			break;

		/* =<hex> */
		hexbuf[0] = src[src_pos+1];
		hexbuf[1] = src[src_pos+2];

		if (hex_to_binary(hexbuf, dest) == 0) {
			src_pos += 2;
			next = src_pos+1;
		} else {
			/* non-hex data, show as-is */
			errors = TRUE;
			next = src_pos;
		}
	}
	buffer_append(dest, src + next, src_size - next);
	return errors ? -1 : 0;
}