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/*
* SCCS: @(#)host.c 1.10 (98/09/01)
*
* UniSoft Ltd., London, England
*
* (C) Copyright 1992 X/Open Company Limited
*
* All rights reserved. No part of this source code may be reproduced,
* stored in a retrieval system, or transmitted, in any form or by any
* means, electronic, mechanical, photocopying, recording or otherwise,
* except as stated in the end-user licence agreement, without the prior
* permission of the copyright owners.
*
* X/Open and the 'X' symbol are trademarks of X/Open Company Limited in
* the UK and other countries.
*/
#ifndef lint
static char sccsid[] = "@(#)host.c 1.10 (98/09/01) TET3 release 3.3";
#endif
/************************************************************************
SCCS: @(#)host.c 1.10 98/09/01 TETware release 3.3
NAME: host.c
PRODUCT: TETware
AUTHOR: Andrew Dingwall, UniSoft Ltd.
DATE CREATED: April 1992
DESCRIPTION:
INET host address lookup function
MODIFICATIONS:
Geoff Clare, UniSoft Ltd., August 1996
Missing <stdio.h> (for sprintf).
Andrew Dingwall, UniSoft Ltd., July 1998
Added support for shared API libraries.
************************************************************************/
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
# include <netinet/in.h>
# include <netdb.h>
#include "dtmac.h"
#include "error.h"
#include "time.h"
#include "dtmsg.h"
#include "ptab.h"
#include "inetlib_in.h"
#ifdef NEEDsrcFile
static char srcFile[] = __FILE__; /* file name for error reporting */
#endif
#define NHCACHE 2 /* no of host cache entries - one for localhost
and one for the master system */
/* host cache structure */
struct hcache {
int hc_refcnt;
struct in_addr hc_addr;
char hc_host[SNAMELEN];
};
static struct hcache hcache[NHCACHE]; /* the cache itself */
/*
** tet_gethostaddr() - find the INET address of a host and return a
** pointer thereto
**
** return (struct in_addr *) 0 if the address cannot be found
*/
TET_IMPORT struct in_addr *tet_gethostaddr(host)
char *host;
{
register struct hcache *cp1, *cp2;
register struct hostent *hp;
register int max;
int err;
/* see if host is already in the cache */
for (cp1 = hcache; cp1 < &hcache[NHCACHE]; cp1++)
if (!strcmp(cp1->hc_host, host)) {
cp1->hc_refcnt++;
return(&cp1->hc_addr);
}
/* look up the host's address in the hosts file */
CLEAR_SOCKET_ERRNO;
if ((hp = gethostbyname(host)) == (struct hostent *) 0) {
err = SOCKET_ERRNO;
error(err != ENOTTY ? err : 0,
"can't find hosts entry for", host);
return((struct in_addr *) 0);
}
/* store the entry in the least used cache slot */
max = (int) ((unsigned) ~0 >> 1);
for (cp2 = cp1 = hcache; cp1 < &hcache[NHCACHE]; cp1++)
if (cp1->hc_refcnt <= 0) {
cp2 = cp1;
break;
}
else if (cp1->hc_refcnt <= max) {
max = cp1->hc_refcnt;
cp2 = cp1;
}
cp2->hc_addr = *((struct in_addr *) hp->h_addr);
cp2->hc_refcnt = 1;
(void) sprintf(cp2->hc_host, "%.*s",
(int) sizeof cp2->hc_host - 1, host);
return(&cp2->hc_addr);
}
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