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/*
* checkalias.c -- check to see if the IP addresses of two hosts are the same
*
* Copyright 1997 by Eric S. Raymond
* For license terms, see the file COPYING in this directory.
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include "fetchmail.h"
int is_ip_alias(const char *name1,const char *name2)
/* Given two hostnames as arguments, returns TRUE if they
* have at least one IP address in common.
* It is meant to be called by the is_host_alias() function in driver.c
* No check is done on errors returned by gethostbyname,
* the calling function does them.
*/
{
typedef unsigned char address_t[sizeof (struct in_addr)];
typedef struct _address_e
{
struct _address_e *next;
address_t address;
}
address_e;
address_e *host_a_addr, *host_b_addr,*dummy_addr;
int i;
struct hostent *hp;
char **p;
hp = gethostbyname(name1);
dummy_addr = (address_e *)NULL;
for (i=0,p = hp->h_addr_list; *p != 0; i++,p++)
{
struct in_addr in;
(void) memcpy(&in.s_addr, *p, sizeof (in.s_addr));
host_a_addr = (address_e *)xmalloc(sizeof( address_e));
memset (host_a_addr,0, sizeof (address_e));
host_a_addr->next = dummy_addr;
(void) memcpy(&host_a_addr->address, *p, sizeof (in.s_addr));
dummy_addr = host_a_addr;
}
hp = gethostbyname(name2);
dummy_addr = (address_e *)NULL;
for (i=0,p = hp->h_addr_list; *p != 0; i++,p++)
{
struct in_addr in;
(void) memcpy(&in.s_addr, *p, sizeof (in.s_addr));
host_b_addr = (address_e *)xmalloc(sizeof( address_e));
memset (host_b_addr,0, sizeof (address_e));
host_b_addr->next = dummy_addr;
(void) memcpy(&host_b_addr->address, *p, sizeof (in.s_addr));
dummy_addr = host_b_addr;
}
while (host_a_addr)
{
while (host_b_addr)
{
if (!memcmp(host_b_addr->address,host_a_addr->address, sizeof (address_t)))
return (TRUE);
host_b_addr = host_b_addr->next;
}
host_a_addr = host_a_addr->next;
}
return (FALSE);
}
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