[Freeipa-devel] [PATCH] 0019 Sync time with NTP before joining the domain

[Alexander Bokovoy]

Hi,

https://fedorahosted.org/freeipa/ticket/1773

-- 
/ Alexander Bokovoy
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>From 8b022ee7b1290cabd4e1a54971dc66420d73c1cc Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <abokovoy at redhat.com>
Date: Wed, 5 Oct 2011 15:02:58 +0300
Subject: [PATCH] Before kinit, try to sync time with the NTP servers of the
 domain we are joining

When running ipa-client-install on a system whose clock is not in sync with the
master, kinit fails and enrollment is aborted. Manual checking of current time
at the master and adjusting on the client-to-be is then needed.

The patch tries to fetch SRV records for NTP servers of the domain we aim to join
and runs ntpdate to get time synchronized. If no SRV records are found, sync with IPA server itself.
If that fails, warn that time might be not in sync with KDC.

https://fedorahosted.org/freeipa/ticket/1773
---
 ipa-client/ipa-install/ipa-client-install |   14 ++++++++++++++
 ipa-client/ipaclient/ipadiscovery.py      |   21 +++++++++++++++++++++
 ipa-client/ipaclient/ntpconf.py           |   22 ++++++++++++++++++++++
 3 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/ipa-client/ipa-install/ipa-client-install b/ipa-client/ipa-install/ipa-client-install
index 70ef811cec5a9107cb110d7ffa2a191fb36ea997..3810caea3eee403d0f225d52e0e5c5b2b8489a78 100755
--- a/ipa-client/ipa-install/ipa-client-install
+++ b/ipa-client/ipa-install/ipa-client-install
@@ -920,6 +920,20 @@ def install(options, env, fstore, statestore):
         nolog = tuple()
         # First test out the kerberos configuration
         try:
+            # Attempt to sync time with IPA server.
+            # We assume that NTP servers are discoverable through SRV records in the DNS
+            # If that fails, we try to sync directly with IPA server, assuming it runs NTP
+            ntp_servers = ipautil.parse_items(ds.ipadnssearchntp(cli_domain))
+            synced_ntp = False
+            if len(ntp_servers) > 0:
+                for s in ntp_servers:
+                   synced_ntp = ipaclient.ntpconf.synconce_ntp(s)
+                   if synced_ntp:
+                       break
+            if not synced_ntp:
+                synced_ntp = ipaclient.ntpconf.synconce_ntp(cli_server)
+            if not synced_ntp:
+                print "Unable to sync time with IPA NTP server, assuming the time is in sync."
             (krb_fd, krb_name) = tempfile.mkstemp()
             os.close(krb_fd)
             if configure_krb5_conf(fstore, cli_basedn, cli_realm, cli_domain, cli_server, cli_kdc, dnsok, options, krb_name):
diff --git a/ipa-client/ipaclient/ipadiscovery.py b/ipa-client/ipaclient/ipadiscovery.py
index 3e31cad37dc1883c01e0729e390c5e5c16e022bd..cd5f81bd5147929deca43e502c4f9b2bdb98f99c 100644
--- a/ipa-client/ipaclient/ipadiscovery.py
+++ b/ipa-client/ipaclient/ipadiscovery.py
@@ -316,6 +316,27 @@ class IPADiscovery:
 
         return servers
 
+    def ipadnssearchntp(self, tdomain):
+        servers = ""
+        rserver = ""
+
+        qname = "_ntp._udp."+tdomain
+        # terminate the name
+        if not qname.endswith("."):
+            qname += "."
+        results = ipapython.dnsclient.query(qname, ipapython.dnsclient.DNS_C_IN, ipapython.dnsclient.DNS_T_SRV)
+
+        for result in results:
+            if result.dns_type == ipapython.dnsclient.DNS_T_SRV:
+                rserver = result.rdata.server.rstrip(".")
+                if servers:
+                    servers += "," + rserver
+                else:
+                    servers = rserver
+                break
+
+        return servers
+
     def ipadnssearchkrb(self, tdomain):
         realm = None
         kdc = None
diff --git a/ipa-client/ipaclient/ntpconf.py b/ipa-client/ipaclient/ntpconf.py
index 8e151089c81fe761dc57fc6e8fb7ff5ba30b98fa..e2d349b166d9fc47bfd48f4c8054e211904778e7 100644
--- a/ipa-client/ipaclient/ntpconf.py
+++ b/ipa-client/ipaclient/ntpconf.py
@@ -132,3 +132,25 @@ def config_ntp(server_fqdn, fstore = None, sysstore = None):
 
     # Restart ntpd
     ipaservices.knownservices.ntpd.restart()
+
+def synconce_ntp(server_fqdn):
+    """
+    Syncs time with specified server using ntpdate.
+    Primarily designed to be used before Kerberos setup
+    to get time following the KDC time
+
+    Returns True if sync was successful
+    """
+    ntpdate="/usr/sbin/ntpdate"
+    result = False
+    if os.path.exists(ntpdate):
+        retries = 2
+        for retry in range(0,3):
+            try:
+                (sout, serr, rcode) = ipautil.run([ntpdate, "-U", "ntp", "-s", "-b", server_fqdn],capture_output=True)
+                if rcode == 0:
+                    result = True
+                    break
+            except:
+                pass
+    return result
-- 
1.7.6.4