getservent.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.
 *
 * 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[] = "@(#)getservent.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <string.h>

#include <stdlib.h>
#include <ctype.h>
#include <net/netdb.h>
#include <stdio.h>
#include <errno.h>
#include <arpa/nameser.h>

#define	MAXALIASES	35

static char SERVDB[] = _PATH_SERVICES;
static FILE *servf = NULL;
static char line[BUFSIZ+1];
static struct servent serv;
static char *serv_aliases[MAXALIASES];
int _serv_stayopen;

void
setservent(f)
	int f;
{
	if (servf == NULL)
		servf = fopen(SERVDB, "r" );
	else
		rewind(servf);
	_serv_stayopen |= f;
}

void
endservent()
{
	if (servf) {
		fclose(servf);
		servf = NULL;
	}
	_serv_stayopen = 0;
}

struct servent *
getservent()
{
	char *p;
	register char *cp, **q;

	if (servf == NULL && (servf = fopen(SERVDB, "r" )) == NULL)
		return (NULL);
again:
	if ((p = fgets(line, BUFSIZ, servf)) == NULL)
		return (NULL);
	if (*p == '#')
		goto again;
	cp = strpbrk(p, "#\n");
	if (cp == NULL)
		goto again;
	*cp = '\0';
	serv.s_name = p;
	p = strpbrk(p, " \t");
	if (p == NULL)
		goto again;
	*p++ = '\0';
	while (*p == ' ' || *p == '\t')
		p++;
	cp = strpbrk(p, ",/");
	if (cp == NULL)
		goto again;
	*cp++ = '\0';
	serv.s_port = htons((u_short)atoi(p));
	serv.s_proto = cp;
	q = serv.s_aliases = serv_aliases;
	cp = strpbrk(cp, " \t");
	if (cp != NULL)
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &serv_aliases[MAXALIASES - 1])
			*q++ = cp;
		cp = strpbrk(cp, " \t");
		if (cp != NULL)
			*cp++ = '\0';
	}
	*q = NULL;
	return (&serv);
}