Add IPv6 support for determining FQDN during ADS join.

Signed-off-by: David Holder <david.holder@erion.co.uk>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Böhme <rb@sernet.de>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Tue May 12 23:35:32 CEST 2015 on sn-devel-104

1 files changed, 33 insertions, 21 deletions

diff --git a/source3/lib/util.c b/source3/lib/util.c
index ec0757e18cd..1d768202448 100644
--- a/source3/lib/util.c
+++ b/source3/lib/util.c
@@ -1836,48 +1836,60 @@ bool unix_wild_match(const char *pattern, const char *string)
 }
 
 /**********************************************************************
- Converts a name to a fully qualified domain name.
- Returns true if lookup succeeded, false if not (then fqdn is set to name)
- Note we deliberately use gethostbyname here, not getaddrinfo as we want
- to examine the h_aliases and I don't know how to do that with getaddrinfo.
-***********************************************************************/
+  Converts a name to a fully qualified domain name.
+  Returns true if lookup succeeded, false if not (then fqdn is set to name)
+  Uses getaddrinfo() with AI_CANONNAME flag to obtain the official
+  canonical name of the host. getaddrinfo() may use a variety of sources
+  including /etc/hosts to obtain the domainname. It expects aliases in
+  /etc/hosts to NOT be the FQDN. The FQDN should come first.
+************************************************************************/
 
 bool name_to_fqdn(fstring fqdn, const char *name)
 {
 	char *full = NULL;
-	struct hostent *hp = gethostbyname(name);
+	struct addrinfo hints;
+	struct addrinfo *result;
+	int s;
+
+	/* Configure hints to obtain canonical name */
+
+	memset(&hints, 0, sizeof(struct addrinfo));
+	hints.ai_family = AF_UNSPEC;    /* Allow IPv4 or IPv6 */
+	hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */
+	hints.ai_flags = AI_CANONNAME;  /* Get host's FQDN */
+	hints.ai_protocol = 0;          /* Any protocol */
 
-	if (!hp || !hp->h_name || !*hp->h_name) {
+	s = getaddrinfo(name, NULL, &hints, &result);
+	if (s != 0) {
+		DEBUG(1, ("getaddrinfo: %s\n", gai_strerror(s)));
 		DEBUG(10,("name_to_fqdn: lookup for %s failed.\n", name));
 		fstrcpy(fqdn, name);
 		return false;
 	}
+	full = result->ai_canonname;
 
-	/* Find out if the fqdn is returned as an alias
+	/* Find out if the FQDN is returned as an alias
 	 * to cope with /etc/hosts files where the first
-	 * name is not the fqdn but the short name */
-	if (hp->h_aliases && (! strchr_m(hp->h_name, '.'))) {
-		int i;
-		for (i = 0; hp->h_aliases[i]; i++) {
-			if (strchr_m(hp->h_aliases[i], '.')) {
-				full = hp->h_aliases[i];
-				break;
-			}
-		}
+	 * name is not the FQDN but the short name.
+	 * getaddrinfo provides no easy way of handling aliases
+	 * in /etc/hosts. Users should make sure the FQDN
+	 * comes first in /etc/hosts. */
+	if (full && (! strchr_m(full, '.'))) {
+		DEBUG(1, ("WARNING: your /etc/hosts file may be broken!\n"));
+		DEBUGADD(1, ("    Full qualified domain names (FQDNs) should not be specified\n"));
+		DEBUGADD(1, ("    as an alias in /etc/hosts. FQDN should be the first name\n"));
+		DEBUGADD(1, ("    prior to any aliases.\n"));
 	}
 	if (full && (strcasecmp_m(full, "localhost.localdomain") == 0)) {
 		DEBUG(1, ("WARNING: your /etc/hosts file may be broken!\n"));
 		DEBUGADD(1, ("    Specifying the machine hostname for address 127.0.0.1 may lead\n"));
 		DEBUGADD(1, ("    to Kerberos authentication problems as localhost.localdomain\n"));
 		DEBUGADD(1, ("    may end up being used instead of the real machine FQDN.\n"));
-		full = hp->h_name;
-	}
-	if (!full) {
-		full = hp->h_name;
 	}
 
 	DEBUG(10,("name_to_fqdn: lookup for %s -> %s.\n", name, full));
 	fstrcpy(fqdn, full);
+	freeaddrinfo(result);           /* No longer needed */
 	return true;
 }