inet_net.c

libcap是一个在linux下的抓包工具

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)inet_network.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include "inetprivate.h"

/*
 * Internet network address interpretation routine.
 * The library routines call this routine to interpret
 * network numbers.
 */
u_int32_t
inet_network(const char *cp)
{
	register u_long val, base, n;
	register char c;
	u_long parts[4], *pp = parts;
	register int i;

again:
	/*
	 * Collect number up to ``.''.
	 * Values are specified as for C:
	 * 0x=hex, 0=octal, other=decimal.
	 */
	val = 0; base = 10;
	/*
	 * The 4.4BSD version of this file also accepts 'x__' as a hexa
	 * number.  I don't think this is correct.  -- Uli
	 */
	if (*cp == '0') {
		if (*++cp == 'x' || *cp == 'X')
			base = 16, cp++;
		else
			base = 8;
	}
	while ((c = *cp)) {
		if (isdigit(c)) {
			val = (val * base) + (c - '0');
			cp++;
			continue;
		}
		if (base == 16 && isxdigit(c)) {
			val = (val << 4) + (c + 10 - (islower(c) ? 'a' : 'A'));
			cp++;
			continue;
		}
		break;
	}
	if (*cp == '.') {
		if (pp >= parts + 4)
			return (INADDR_NONE);
		*pp++ = val, cp++;
		goto again;
	}
	if (*cp && !isspace(*cp))
		return (INADDR_NONE);
	*pp++ = val;
	n = pp - parts;
	if (n > 4)
		return (INADDR_NONE);
	for (val = 0, i = 0; i < (int)n; i++) {
		val <<= 8;
		val |= parts[i] & 0xff;
	}
	return (val);
}