From 01402e857c99a3a8aa76535cde81c479e330a0a6 Mon Sep 17 00:00:00 2001
From: Bob Ball <bob.ball@citrix.com>
Date: Mon, 5 Sep 2016 17:12:59 +0100
Subject: [PATCH] Check for HIMN using dhcp discovery

A future plan for this plugin is to not require the HIMN XC
plugin but to support adding the network just in XenCenter
(with hidden objects displayed). Therefore the fuel plugin
should try to auto detect the HIMN as the MAC would not be
written to XenStore.

Change-Id: I7bb120ab79b486fa5ee201385e91c3c450454527
---
 plugin_source/deployment_scripts/utils.py | 107 +++++++++++++++++-----
 1 file changed, 82 insertions(+), 25 deletions(-)

diff --git a/plugin_source/deployment_scripts/utils.py b/plugin_source/deployment_scripts/utils.py
index 983a956..73982c3 100644
--- a/plugin_source/deployment_scripts/utils.py
+++ b/plugin_source/deployment_scripts/utils.py
@@ -60,7 +60,11 @@ def execute(*cmd, **kwargs):
         logging.error(err)
 
     if proc.returncode is not None and proc.returncode != 0:
-        raise ExecutionError(err)
+        if proc.returncode in kwargs.get('allowed_return_codes', [0]):
+            logging.info('Swallowed acceptable return code of %d',
+                         proc.returncode)
+        else:
+            raise ExecutionError(err)
 
     return out
 
@@ -114,6 +118,57 @@ def get_options(astute, astute_section=ASTUTE_SECTION):
         options['install_xapi']
 
 
+def eth_to_mac(eth):
+    return netifaces.ifaddresses(eth).get(netifaces.AF_LINK)[0]['addr']
+
+
+def detect_himn_ip(eths=None):
+    if eths is None:
+        eths = netifaces.interfaces()
+    for eth in eths:
+        ip = netifaces.ifaddresses(eth).get(netifaces.AF_INET)
+        if ip is None:
+            continue
+        himn_local = ip[0]['addr']
+        himn_xs = '.'.join(himn_local.split('.')[:-1] + ['1'])
+        if HIMN_IP == himn_xs:
+            return eth, ip
+    return None, None
+
+
+def find_eth_xenstore():
+    domid = execute('xenstore-read', 'domid')
+    himn_mac = execute(
+        'xenstore-read',
+        '/local/domain/%s/vm-data/himn_mac' % domid)
+    logging.info('himn_mac: %s' % himn_mac)
+
+    eths = [eth for eth in netifaces.interfaces()
+            if eth_to_mac(eth) == himn_mac]
+    if len(eths) != 1:
+        reportError('Cannot find eth matches himn_mac')
+
+    return eths[0]
+
+
+def detect_eth_dhclient():
+    for eth in netifaces.interfaces():
+        # Don't try and dhclient for devices an IP address already
+        ip = netifaces.ifaddresses(eth).get(netifaces.AF_INET)
+        if ip:
+            continue
+
+        # DHCP replies from HIMN should be super fast
+        execute('timeout', '2s', 'dhclient', eth,
+                allowed_return_codes=[0, 124])
+        try:
+            _, ip = detect_himn_ip([eth])
+            if ip is not None:
+                return eth
+        finally:
+            execute('dhclient', '-r', eth)
+
+
 def init_eth():
     """Initialize the net interface connected to HIMN
 
@@ -121,26 +176,23 @@ def init_eth():
         the IP addresses of local host and hypervisor.
     """
 
-    def _mac(eth):
-        return netifaces.ifaddresses(eth).get(netifaces.AF_LINK)[0]['addr']
-
-    domid = execute('xenstore-read', 'domid')
-    himn_mac = execute(
-        'xenstore-read',
-        '/local/domain/%s/vm-data/himn_mac' % domid)
-    logging.info('himn_mac: %s' % himn_mac)
-
-    eths = [eth for eth in netifaces.interfaces() if _mac(eth) == himn_mac]
-    if len(eths) != 1:
-        reportError('Cannot find eth matches himn_mac')
-
-    eth = eths[0]
-
-    logging.info('himn_eth: %s' % eth)
-
-    ip = netifaces.ifaddresses(eth).get(netifaces.AF_INET)
+    eth, ip = detect_himn_ip()
 
     if not ip:
+        eth = None
+        try:
+            eth = find_eth_xenstore()
+        except Exception:
+            logging.debug('Failed to find MAC through xenstore', exc_info=True)
+
+        if eth is None:
+            eth = detect_eth_dhclient()
+
+        if eth is None:
+            reportError('Failed to detect HIMN ethernet device')
+
+        logging.info('himn_eth: %s' % eth)
+
         execute('dhclient', eth)
         fname = '/etc/network/interfaces.d/ifcfg-' + eth
         s = ('auto {eth}\n'
@@ -151,13 +203,18 @@ def init_eth():
         logging.info('%s created' % fname)
         execute('ifdown', eth)
         execute('ifup', eth)
-        ip = netifaces.ifaddresses(eth).get(netifaces.AF_INET)
 
-    if ip:
+        ip = netifaces.ifaddresses(eth).get(netifaces.AF_INET)
         himn_local = ip[0]['addr']
         himn_xs = '.'.join(himn_local.split('.')[:-1] + ['1'])
-        if HIMN_IP == himn_xs:
-            logging.info('himn_local: %s' % himn_local)
-            return eth, himn_local
+        if HIMN_IP != himn_xs:
+            # Not on the HIMN - we failed here.
+            logging.info('himn_local: DHCP returned incorrect IP %s' %
+                         ip[0]['addr'])
+            ip = None
 
-    reportError('HIMN failed to get IP address from Hypervisor')
+    if not ip:
+        reportError('HIMN failed to get IP address from Hypervisor')
+
+    logging.info('himn_local: %s' % ip[0]['addr'])
+    return eth, ip[0]['addr']