gethostent.c

minux的源代码,一个非常小的操作系统

/*
 * Copyright (c) 1985, 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)gethostnamadr.c	6.41 (Berkeley) 6/1/90";
#endif /* LIBC_SCCS and not lint */

/* Prefix the functions defined here with underscores to distinguish them
 * from the newer replacements in the resolver library.
 */
#define sethostent	_sethostent
#define endhostent	_endhostent
#define gethostent	_gethostent
#define gethostbyname	_gethostbyname
#define gethostbyaddr	_gethostbyaddr

#ifdef _MINIX
#include <sys/types.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

#include <net/hton.h>
#include <net/gen/nameser.h>
#include <net/gen/netdb.h>
#include <net/gen/in.h>
#include <net/gen/inet.h>
#include <net/gen/resolv.h>
#include <net/gen/socket.h>
#else
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <ctype.h>
#include <netdb.h>
#include <stdio.h>
#include <errno.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <resolv.h>
#endif /* !_MINIX */

#define	MAXALIASES	35
#define	MAXADDRS	35

#ifdef _MINIX
typedef u32_t u_long;
typedef u16_t u_short;
typedef u8_t u_char;

#define bcmp	memcmp
#endif /* _MINIX */

static struct hostent host;
static char *host_aliases[MAXALIASES];
static char hostbuf[BUFSIZ+1];
static FILE *hostf = NULL;
static u_long hostaddr[(MAXADDRS+sizeof(u_long)-1)/sizeof(u_long)];
static char *host_addrs[2];
static int stayopen = 0;

#ifndef _MINIX
char *strpbrk();
#endif /* !_MINIX */

void
sethostent(f)
	int f;
{
	if (hostf == NULL)
		hostf = fopen(_PATH_HOSTS, "r" );
	else
		rewind(hostf);
	stayopen |= f;
}

void
endhostent()
{
	if (hostf && !stayopen) {
		(void) fclose(hostf);
		hostf = NULL;
	}
}

struct hostent *
gethostent()
{
	char *p;
	register char *cp, **q;

	if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
		return (NULL);
again:
	if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
		return (NULL);
	if (*p == '#')
		goto again;
	cp = strpbrk(p, "#\n");
	if (cp == NULL)
		goto again;
	*cp = '\0';
	cp = strpbrk(p, " \t");
	if (cp == NULL)
		goto again;
	*cp++ = '\0';
	/* THIS STUFF IS INTERNET SPECIFIC */
#if BSD >= 43 || defined(h_addr)	/* new-style hostent structure */
	host.h_addr_list = host_addrs;
#endif
	host.h_addr = (char *) hostaddr;
	*((u_long *)host.h_addr) = inet_addr(p);
	host.h_length = sizeof (u_long);
	host.h_addrtype = AF_INET;
	while (*cp == ' ' || *cp == '\t')
		cp++;
	host.h_name = cp;
	q = host.h_aliases = host_aliases;
	cp = strpbrk(cp, " \t");
	if (cp != NULL) 
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &host_aliases[MAXALIASES - 1])
			*q++ = cp;
		cp = strpbrk(cp, " \t");
		if (cp != NULL)
			*cp++ = '\0';
	}
	*q = NULL;
	return (&host);
}

struct hostent *
gethostbyname(name)
	char *name;
{
	register struct hostent *p;
	register char **cp;
	
	sethostent(0);
	while (p = gethostent()) {
		if (strcasecmp(p->h_name, name) == 0)
			break;
		for (cp = p->h_aliases; *cp != 0; cp++)
			if (strcasecmp(*cp, name) == 0)
				goto found;
	}
found:
	endhostent();
	return (p);
}

struct hostent *
gethostbyaddr(addr, len, type)
	const char *addr;
	int len, type;
{
	register struct hostent *p;

	sethostent(0);
	while (p = gethostent())
		if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
			break;
	endhostent();
	return (p);
}