Use NSS for name->resolution in IPA installer

This fixes scenarios where IPA server is not able to resolve own name
and option --ip-address was not specified by the user.

This partially reverts changes from commit
dc405005f5

https://fedorahosted.org/freeipa/ticket/5962

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipapython/dnsutil.py

@@ -321,7 +321,7 @@ def resolve_rrsets(fqdn, rdtypes):
 
 
 def resolve_ip_addresses(fqdn):
-    """Get IP addresses from DNS A/AAAA records for given host.
+    """Get IP addresses from DNS A/AAAA records for given host (using DNS).
     :returns:
         list of IP addresses as CheckedIPAddress objects
     """

ipaserver/install/bindinstance.py

@@ -910,9 +910,7 @@ class BindInstance(service.Service):
             if fqdn == self.fqdn:
                 continue
 
-            addrs = dnsutil.resolve_ip_addresses(fqdn)
-            # hack, will go away with locations
-            addrs = [str(addr) for addr in addrs]
+            addrs = installutils.resolve_ip_addresses_nss(fqdn)
 
             root_logger.debug("Adding DNS records for master %s" % fqdn)
             self.__add_master_records(fqdn, addrs)

ipaserver/install/installutils.py

@@ -447,6 +447,46 @@ def create_keytab(path, principal):
 
     kadmin("ktadd -k " + path + " " + principal)
 
+def resolve_ip_addresses_nss(fqdn):
+    """Get list of IP addresses for given host (using NSS/getaddrinfo).
+    :returns:
+        list of IP addresses as CheckedIPAddress objects
+    """
+    # make sure the name is fully qualified
+    # so search path from resolv.conf does not apply
+    fqdn = str(dnsutil.DNSName(fqdn).make_absolute())
+    try:
+        addrinfos = socket.getaddrinfo(fqdn, None,
+                                       socket.AF_UNSPEC, socket.SOCK_STREAM)
+    except socket.error as ex:
+        if ex.errno == socket.EAI_NODATA or ex.errno == socket.EAI_NONAME:
+            root_logger.debug('Name %s does not have any address: %s',
+                              fqdn, ex)
+            return set()
+        else:
+            raise
+
+    # accept whatever we got from NSS
+    ip_addresses = set()
+    for ai in addrinfos:
+        try:
+            ip = ipautil.CheckedIPAddress(ai[4][0],
+                                          parse_netmask=False,
+                                          # these are unreliable, disable them
+                                          allow_network=True,
+                                          allow_loopback=True,
+                                          allow_broadcast=True,
+                                          allow_multicast=True)
+        except ValueError as ex:
+            # getaddinfo may return link-local address other similar oddities
+            # which are not accepted by CheckedIPAddress - skip these
+            root_logger.warning('Name %s resolved to an unacceptable IP '
+                                'address %s: %s', fqdn, ai[4][0], ex)
+        else:
+            ip_addresses.add(ip)
+    root_logger.debug('Name %s resolved to %s', fqdn, ip_addresses)
+    return ip_addresses
+
 def get_host_name(no_host_dns):
     """
     Get the current FQDN from the socket and verify that it is valid.
@@ -461,8 +501,7 @@ def get_host_name(no_host_dns):
     return hostname
 
 def get_server_ip_address(host_name, unattended, setup_dns, ip_addresses):
-    # Check we have a public IP that is associated with the hostname
-    hostaddr = dnsutil.resolve_ip_addresses(host_name)
+    hostaddr = resolve_ip_addresses_nss(host_name)
     if hostaddr.intersection(
             {ipautil.CheckedIPAddress(ip, allow_loopback=True)
              for ip in ['127.0.0.1', '::1']}):