/*
 * This module contains the function for decoding hex strings.
 */

#include <sys/types.h>
#include <ctype.h>
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <stdlib.h>

decode_hex_digit(c)
{
	if (c >= '0' && c <= '9')
		return(c - '0');
	if (c >= 'A' && c <= 'F')
		return(c - 'A' + 10);
	if (c >= 'a' && c <= 'f')
		return(c - 'a' + 10);
	return(-1);
}

decode_hex_data_from_string(arg, databuf, maxlen)
	char *arg;
	u_char *databuf;
	unsigned maxlen;
{
	unsigned count;

	for (count = 0; ; count++) {
		while (isspace(*arg))
			arg++;
		if (!*arg)
			break;
		if (!isxdigit(arg[0]) || !isxdigit(arg[1])) {
			fprintf(stderr, "error: invalid hex string input\n");
			return(-1);
		}
		if (count >= maxlen) {
			fprintf(stderr, "error: hex input data is too long\n");
			return(-1);
		}
		databuf[count] = (decode_hex_digit(arg[0]) << 4) |
				 decode_hex_digit(arg[1]);
		arg += 2;
	}
	if (!count) {
		fprintf(stderr, "error: empty hex string argument\n");
		return(-1);
	}
	return(count);
}