Why does getaddrinfo return only one address?

Any guesses why the following program works fine on Solaris, but not
on linux?

/*
* Author: David Lehmann 3/27/2003
* Purpose: Demonstrate that getaddrinfo returns one address.
*
* If /etc/hosts contains the following two entries, BOTH should be
* obtained by getaddinfo. Currently, only the first entry is obtained.
* This identical program works fine on Solaris.
*
* 172.25.4.94 fred fred-1
* 10.2.89.3 fred fred-2
*/


#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

void print_addr(char *host, int pf);
void print_ip_addr(struct addrinfo *a, int count);

int
main(int argc, char **argv)
{
char *host = argv[1];

if (!host)
{
fprintf(stderr, "Usage: %s host\n", argv[0]);
exit(1);
}

printf("host %s, searching for IPv4 addresses...\n", argv[0]);
print_addr(host, PF_INET);

printf("host %s, searching for IPv6 addresses...\n", argv[0]);
print_addr(host, PF_INET6);

return 0;
}

void
print_addr(char *host, int pf)
{
struct addrinfo *res = 0;
struct addrinfo hints; /* see getaddrinfo */
int error;
int i;

memset(&hints, 0, sizeof(hints));
hints.ai_family = pf;
hints.ai_socktype = SOCK_RAW;
error = getaddrinfo(host, NULL, &hints, &res);

if (error)
{
fprintf(stderr, "getaddrinfo failed: %d - %s\n",
error, gai_strerror(error));
return;
}

print_ip_addr(res, 0);
freeaddrinfo(res);
}

void
print_ip_addr(struct addrinfo *a, int count)
{
char buf[INET6_ADDRSTRLEN + 1];
void *addr;

if (!a)
return;

if (a->ai_family == AF_INET)
addr = &((struct sockaddr_in *)a->ai_addr)->sin_addr;
else
addr = &((struct sockaddr_in6 *)a->ai_addr)->sin6_addr;

inet_ntop(a->ai_family, addr, buf, sizeof(buf));
printf("%d: %s\n", count, buf);

print_ip_addr(a->ai_next, count + 1);
}

David <(E-Mail Removed)> wrote:
> Any guesses why the following program works fine on Solaris, but not
> on linux?

cut it down to 10 lines at most and people may have an opinion.
Add your running tests, debugging info, and people may have some data.

> * If /etc/hosts contains the following two entries, BOTH should be
> * obtained by getaddinfo. Currently, only the first entry is obtained.
> * This identical program works fine on Solaris.
> *
> * 172.25.4.94 fred fred-1
> * 10.2.89.3 fred fred-2

Those entries are incorrect. man hosts. It says:

For each host a single line should be present with the following
information:
IP_address canonical_hostname aliases

You have multiple lines for fred, and fred is not a FQDN either, if you
care, so the canonicalisation is off.

I've never heard of getaddinfo. The standard way of interrogating the
resolver tables is with gethostbyname:


The domain name queries carried out by gethostbyname() and
gethostbyaddr() use a combination of any or all of the name
server named(8), a broken out line from /etc/hosts, and the
Network Information Service (NIS or YP), depending upon the
contents of the order line in /etc/host.conf. (See resolv+(8)).
The default action is to query named(8), followed by /etc/hosts.




Peter